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<!-- DFIN ActiveDisclosure(SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2021-03-25T00:04:05.6417066+00:00 -->
<!-- Version            : 5.0.1.571 -->
<!-- Package ID         : 7ade75fdc1d245c2b73727bcd69694ea -->
<!-- Copyright (c) 2021 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentAnnualReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Annual Report</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentPeriodEndDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Period End Date</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentTransitionReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Transition Report</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentTransitionReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Transition Report</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFileNumber" xlink:type="locator" xlink:label="dei_EntityFileNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityRegistrantName" xlink:type="locator" xlink:label="dei_EntityRegistrantName" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityRegistrantName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Registrant Name</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityRegistrantName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Registrant Name</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityIncorporationStateCountryCode" xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation, State or Country Code</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation State Country Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityTaxIdentificationNumber" xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Tax Identification Number</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine1" xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Address Line One</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address Address Line1</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine2_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Address Line Two</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressCityOrTown" xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, City or Town</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address City Or Town</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressStateOrProvince" xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressPostalZipCode" xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, Postal Zip Code</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">City Area Code</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LocalPhoneNumber" xlink:type="locator" xlink:label="dei_LocalPhoneNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Local Phone Number</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_Security12bTitle" xlink:type="locator" xlink:label="dei_Security12bTitle" />
    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title of 12(b) Security</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_SecurityExchangeName" xlink:type="locator" xlink:label="dei_SecurityExchangeName" />
    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Security Exchange Name</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_SecurityExchangeName_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security Exchange Name</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Interactive Data Current</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFilerCategory" xlink:type="locator" xlink:label="dei_EntityFilerCategory" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFilerCategory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Filer Category</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntitySmallBusiness" xlink:type="locator" xlink:label="dei_EntitySmallBusiness" />
    <link:label xml:lang="en-US" xlink:label="dei_EntitySmallBusiness_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Small Business</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Liabilities Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities, net of current portion</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="us-gaap_OtherLiabilitiesNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities" xlink:type="locator" xlink:label="us-gaap_Liabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Liabilities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and contingencies (Note 7)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:type="locator" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock, $0.0001 par value; no shares and 54,350,179 shares authorized at December 31, 2020 and 2019, respectively; no shares and 27,283,973 shares issued and outstanding at December 31, 2020 and 2019, respectively</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:to="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Carrying Amount Attributable To Parent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders&apos; equity (deficit):</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue" xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, $0.0001 par value; 54,350,179 shares and no shares authorized at December 31, 2020 and 2019, respectively; no shares issued and outstanding at December 31, 2020 and 2019</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue" xlink:type="locator" xlink:label="us-gaap_CommonStockValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, $0.0001 par value; 100,000,000 and 71,919,982 shares authorized at December 31, 2020 and 2019, respectively; 32,627,963 and 1,600,601 shares issued and outstanding at December 31, 2020 and 2019, respectively</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Additional Paid In Capital Common Stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated other comprehensive loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Other Comprehensive Income Loss Net Of Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated deficit</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings Accumulated Deficit</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total stockholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_StockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities, convertible preferred stock and stockholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:type="locator" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock, par value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:to="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Par Or Stated Value Per Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesAuthorized" xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock, shares authorized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesAuthorized" xlink:to="us-gaap_TemporaryEquitySharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Shares Authorized</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesIssued" xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock, shares issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesIssued" xlink:to="us-gaap_TemporaryEquitySharesIssued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Shares Issued</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock, shares outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesOutstanding" xlink:to="us-gaap_TemporaryEquitySharesOutstanding_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Shares Outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, par value</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Par Or Stated Value Per Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares authorized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Authorized</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Issued</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock, shares outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesOutstanding" xlink:to="us-gaap_PreferredStockSharesOutstanding_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Par Or Stated Value Per Share</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and development</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">General and administrative</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GeneralAndAdministrativeExpense" xlink:to="us-gaap_GeneralAndAdministrativeExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">General And Administrative Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses" xlink:type="locator" xlink:label="us-gaap_OperatingExpenses" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating expenses</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Expenses</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Loss from operations</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Income Loss</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpenseAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income (expense), net:</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in fair value of preferred stock purchase right liability</link:label>
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    <link:label xml:lang="en-US" xlink:label="nktx_ChangeInFairValueOfDerivativeLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in fair value of derivative liability</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:type="locator" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentIncomeNet" xlink:type="locator" xlink:label="us-gaap_InvestmentIncomeNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentIncomeNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest income</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentIncomeNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment Income Net</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income (expense), net</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nonoperating Income Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net loss</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Income Loss</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</link:label>
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    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Stock Issued During Period Shares New Issues</link:label>
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    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityPreferredStockPurchaseRightLiabilityReversalUponIssuanceOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Preferred Stock Purchase Right Liability Reversal Upon Issuance Of Convertible Securities</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Reclassification Of Preferred Stock Purchase Right Liability To Equity Upon Issuance Of Convertible Preferred Stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockAmountConverted1" xlink:type="locator" xlink:label="us-gaap_ConversionOfStockAmountConverted1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConversionOfStockAmountConverted1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, conversion of convertible preferred stock to common stock</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesConverted1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConversionOfStockSharesConverted1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, conversion of convertible preferred stock to common stock, Shares</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion of convertible preferred stock to common stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Conversion Of Convertible Securities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion of convertible preferred stock to common stock, Shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Conversion Of Convertible Securities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock upon initial public offering, net of issuance costs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value New Issues</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock upon initial public offering, net of issuance costs, Shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares New Issues</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodValueVestingOfSharesOfCommonStockSubjectToRepurchase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting of shares of common stock subject to repurchase</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodValueVestingOfSharesOfCommonStockSubjectToRepurchase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Vesting Of Shares Of Common Stock Subject To Repurchase</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodSharesVestingOfSharesOfCommonStockSubjectToRepurchase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting of shares of common stock subject to repurchase, Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodSharesVestingOfSharesOfCommonStockSubjectToRepurchase_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Vesting Of Shares Of Common Stock Subject To Repurchase</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock upon exercise of stock option, net of repurchase</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Stock Options Exercised</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock upon exercise of stock option, net of repurchase, Shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Stock Options Exercised</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based compensation expense</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Temporary Equity, Ending Balance, Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Temporary Equity, Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance, Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_NonCashInterestExpense" xlink:type="locator" xlink:label="nktx_NonCashInterestExpense" />
    <link:label xml:lang="en-US" xlink:label="nktx_NonCashInterestExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non cash interest expense.</link:label>
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncreaseDecreaseInAccountsPayableAndAccruedAndOtherLiabilities" xlink:type="locator" xlink:label="nktx_IncreaseDecreaseInAccountsPayableAndAccruedAndOtherLiabilities" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncreaseDecreaseInAccountsPayableAndAccruedAndOtherLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase (Decrease) in accounts payable and accrued and other liabilities.</link:label>
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_ProceedsFromIssuanceOfConvertiblePreferredStockNetOfIssuanceCosts" xlink:type="locator" xlink:label="nktx_ProceedsFromIssuanceOfConvertiblePreferredStockNetOfIssuanceCosts" />
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_ProceedsFromEarlyExerciseOfStockOptions" xlink:type="locator" xlink:label="nktx_ProceedsFromEarlyExerciseOfStockOptions" />
    <link:label xml:lang="en-US" xlink:label="nktx_ProceedsFromEarlyExerciseOfStockOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds from early exercise of stock options.</link:label>
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_DeferredOfferingCostsIncludedInAccountsPayableAndAccruedLiabilities" xlink:type="locator" xlink:label="nktx_DeferredOfferingCostsIncludedInAccountsPayableAndAccruedLiabilities" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Profit Loss</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation And Amortization</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows from investing activities:</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:type="locator" xlink:label="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in investing activities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Investing Activities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows from financing activities:</link:label>
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    <link:label xml:lang="en-US" xlink:label="nktx_ProceedsFromIssuanceOfConvertiblePreferredStockNetOfIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from issuance of convertible preferred stock, net of issuance costs</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromConvertibleDebt" xlink:type="locator" xlink:label="us-gaap_ProceedsFromConvertibleDebt" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reconciliation on Income Taxes Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Effective Income Tax Rate Reconciliation Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Significant Components of Deferred Tax Assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Deferred Tax Assets And Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Changes in Gross Unrecognized Tax Benefits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:to="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Unrecognized Tax Benefits Roll Forward Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfStockByClassTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfStockByClassTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Stock By Class [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_ScheduleOfStockByClassTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfStockByClassTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Stock By Class [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:type="locator" xlink:label="us-gaap_SubsidiarySaleOfStockAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SubsidiarySaleOfStockAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsidiary Sale Of Stock [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Of Stock Name Of Transaction [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IPOMember" xlink:type="locator" xlink:label="us-gaap_IPOMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">IPO</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IPOMember" xlink:to="us-gaap_IPOMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">I P O [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OverAllotmentOptionMember" xlink:type="locator" xlink:label="us-gaap_OverAllotmentOptionMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OverAllotmentOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Underwriters Option to Purchase Additional Shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OverAllotmentOptionMember" xlink:to="us-gaap_OverAllotmentOptionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OverAllotmentOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Over Allotment Option [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeriesBConvertiblePreferredStockMember" xlink:type="locator" xlink:label="nktx_SeriesBConvertiblePreferredStockMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series B convertible preferred stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeriesBConvertiblePreferredStockMember" xlink:to="nktx_SeriesBConvertiblePreferredStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series B Convertible Preferred Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series B Convertible Preferred Stock [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:type="locator" xlink:label="us-gaap_ClassOfStockLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ClassOfStockLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Stock [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ClassOfStockLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ClassOfStockLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Stock [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfOperatingSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfOperatingSegments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfOperatingSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of operating segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfOperatingSegments" xlink:to="us-gaap_NumberOfOperatingSegments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfOperatingSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Operating Segments</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares issued during period</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:type="locator" xlink:label="us-gaap_SharesIssuedPricePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued, price per share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssuedPricePerShare" xlink:to="us-gaap_SharesIssuedPricePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Shares Issued Price Per Share</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Conversion of convertible preferred stock to common stock</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Net proceeds after deducting underwriting discounts,commissions and other offering costs</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments" xlink:type="locator" xlink:label="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments" />
    <link:label xml:lang="en-US" xlink:label="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash cash equivalents restricted cash and short term investments.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments" xlink:to="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel">Accumulated deficit</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash, cash equivalents, restricted cash and short-term investments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CashCashEquivalentsRestrictedCashAndShortTermInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash Cash Equivalents Restricted Cash And Short Term Investments</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Convertible Preferred Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Temporary equity, shares issued</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AccountingPoliciesLineItems" xlink:type="locator" xlink:label="nktx_AccountingPoliciesLineItems" />
    <link:label xml:lang="en-US" xlink:label="nktx_AccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Accounting policies.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AccountingPoliciesLineItems" xlink:to="nktx_AccountingPoliciesLineItems_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AccountingPoliciesTable" xlink:type="locator" xlink:label="nktx_AccountingPoliciesTable" />
    <link:label xml:lang="en-US" xlink:label="nktx_AccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Accounting policies.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AccountingPoliciesTable" xlink:to="nktx_AccountingPoliciesTable_lbl" />
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    <link:label xml:lang="en-US" xlink:label="nktx_AccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Policies [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeAxis" xlink:to="srt_RangeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeMember" xlink:to="srt_RangeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:type="locator" xlink:label="us-gaap_TypeOfArrangementAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TypeOfArrangementAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Collaborative Arrangement and Arrangement Other than Collaborative</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_TypeOfArrangementAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TypeOfArrangementAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Type Of Arrangement [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:type="locator" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Collaborative Arrangement and Arrangement Other than Collaborative</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Arrangements And Nonarrangement Transactions [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CollaborationAndLicenseAgreementMember" xlink:type="locator" xlink:label="nktx_CollaborationAndLicenseAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_CollaborationAndLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Collaboration and license agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CollaborationAndLicenseAgreementMember" xlink:to="nktx_CollaborationAndLicenseAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_CollaborationAndLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Collaboration and License Agreement</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsFairValueDisclosure" />
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm" xlink:type="locator" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm" />
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value of preferred stock purchase right liability outstanding term.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm" xlink:to="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value of preferred stock purchase right liability percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Of Preferred Stock Purchase Right Liability Percentage</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityDiscountRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value of preferred stock purchase right liability discount rate</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityDiscountRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Of Preferred Stock Purchase Right Liability Discount Rate</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value of preferred stock purchase right liability outstanding term</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfPreferredStockPurchaseRightLiabilityOutstandingTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Of Preferred Stock Purchase Right Liability Outstanding Term</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock" xlink:type="locator" xlink:label="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock" />
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value measurement with unobservable inputs reconciliations Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock" xlink:to="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance, December 31, 2019</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Reclassification of preferred stock purchase right liability to equity upon issuance of convertible preferred stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueMeasurementWithUnobservableInputsReconciliationsReclassificationOfPreferredStockPurchaseRightLiabilityToEquityUponIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliations Reclassification Of Preferred Stock Purchase Right Liability To Equity Upon Issuance Of Convertible Preferred Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Balance, December 31, 2020</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrepaidExpenseCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prepaid expenses</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseCurrent" xlink:to="us-gaap_PrepaidExpenseCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrepaidExpenseCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Prepaid Expense Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other current assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsCurrent" xlink:to="us-gaap_OtherAssetsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total prepaid expenses and other current assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment By Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Lived Tangible Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:type="locator" xlink:label="us-gaap_LeaseholdImprovementsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leasehold Improvements</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseholdImprovementsMember" xlink:to="us-gaap_LeaseholdImprovementsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Leasehold Improvements [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:type="locator" xlink:label="us-gaap_FurnitureAndFixturesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Furniture and Fixtures</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FurnitureAndFixturesMember" xlink:to="us-gaap_FurnitureAndFixturesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Furniture And Fixtures [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ResearchEquipmentMember" xlink:type="locator" xlink:label="nktx_ResearchEquipmentMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_ResearchEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Research equipment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ResearchEquipmentMember" xlink:to="nktx_ResearchEquipmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ResearchEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research Equipment</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ResearchEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research Equipment [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ComputersAndSoftwareMember" xlink:type="locator" xlink:label="nktx_ComputersAndSoftwareMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_ComputersAndSoftwareMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Computers and software.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ComputersAndSoftwareMember" xlink:to="nktx_ComputersAndSoftwareMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ComputersAndSoftwareMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Computers and Software</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ComputersAndSoftwareMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Computers And Software [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:type="locator" xlink:label="us-gaap_ConstructionInProgressMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Construction in Progress</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConstructionInProgressMember" xlink:to="us-gaap_ConstructionInProgressMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConstructionInProgressMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Construction In Progress [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property Plant And Equipment [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total property and equipment</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentGross" xlink:to="us-gaap_PropertyPlantAndEquipmentGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Gross</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less accumulated depreciation and amortization</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Depreciation Depletion And Amortization Property Plant And Equipment</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total property and equipment, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationDepletionAndAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation and amortization expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DepreciationDepletionAndAmortization" xlink:to="us-gaap_DepreciationDepletionAndAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation Depletion And Amortization</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AccruedResearchAndDevelopmentCostsCurrent" xlink:type="locator" xlink:label="nktx_AccruedResearchAndDevelopmentCostsCurrent" />
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedResearchAndDevelopmentCostsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued research and development costs current.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AccruedResearchAndDevelopmentCostsCurrent" xlink:to="nktx_AccruedResearchAndDevelopmentCostsCurrent_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent" xlink:type="locator" xlink:label="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued property and equipment liabilities current.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent" xlink:to="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_DeferredOfferingCostsLiabilitiesCurrent" xlink:type="locator" xlink:label="nktx_DeferredOfferingCostsLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="nktx_DeferredOfferingCostsLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred offering costs liabilities current.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_DeferredOfferingCostsLiabilitiesCurrent" xlink:to="nktx_DeferredOfferingCostsLiabilitiesCurrent_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Related Liabilities Current</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedResearchAndDevelopmentCostsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued research and development costs</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedResearchAndDevelopmentCostsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Research And Development Costs Current</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued property and equipment</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AccruedPropertyAndEquipmentLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Property And Equipment Liabilities Current</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_DeferredOfferingCostsLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred offering costs</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_DeferredOfferingCostsLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Offering Costs Liabilities Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other accrued and current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent" xlink:to="us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable And Other Accrued Liabilities Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total accrued and other liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable And Accrued Liabilities Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCostAbstract" xlink:type="locator" xlink:label="us-gaap_LeaseCostAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCostAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease, Cost [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseCostAbstract" xlink:to="us-gaap_LeaseCostAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCostAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Cost [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseCost" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseCost" xlink:to="us-gaap_OperatingLeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableLeaseCost" xlink:type="locator" xlink:label="us-gaap_VariableLeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable lease expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableLeaseCost" xlink:to="us-gaap_VariableLeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermLeaseCost" xlink:type="locator" xlink:label="us-gaap_ShortTermLeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term lease expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermLeaseCost" xlink:to="us-gaap_ShortTermLeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCost" xlink:type="locator" xlink:label="us-gaap_LeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_LeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Cost</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract" xlink:type="locator" xlink:label="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash paid for amounts included in the measurement of lease liabilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract" xlink:to="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract" xlink:type="locator" xlink:label="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract" />
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lease liabilities arising from obtaining right-of-use assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract" xlink:to="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash paid for amounts included in the measurement of lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash Paid For Amounts Included In Measurement Of Lease Liabilities [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:type="locator" xlink:label="us-gaap_OperatingLeasePayments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating cash flows used for operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasePayments" xlink:to="us-gaap_OperatingLeasePayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liabilities arising from obtaining right-of-use assets</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseLiabilitiesArisingFromObtainingRightOfUseAssetsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Liabilities Arising From Obtaining Right Of Use Assets [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:type="locator" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:to="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Right Of Use Asset Obtained In Exchange For Operating Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:type="locator" xlink:label="us-gaap_LesseeLeaseDescriptionTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee Lease Description [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_LesseeLeaseDescriptionTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Description [Table]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CorporateOfficeAndLaboratorySpaceMember" xlink:type="locator" xlink:label="nktx_CorporateOfficeAndLaboratorySpaceMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratorySpaceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Corporate office and laboratory space.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CorporateOfficeAndLaboratorySpaceMember" xlink:to="nktx_CorporateOfficeAndLaboratorySpaceMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratorySpaceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Corporate Office and Laboratory Space</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratorySpaceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Corporate Office And Laboratory Space [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_VivariumMember" xlink:type="locator" xlink:label="nktx_VivariumMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_VivariumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Vivarium.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_VivariumMember" xlink:to="nktx_VivariumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_VivariumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vivarium</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_VivariumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vivarium [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CorporateOfficeAndLaboratoryFacilitiesMember" xlink:type="locator" xlink:label="nktx_CorporateOfficeAndLaboratoryFacilitiesMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratoryFacilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Corporate office and laboratory facilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CorporateOfficeAndLaboratoryFacilitiesMember" xlink:to="nktx_CorporateOfficeAndLaboratoryFacilitiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratoryFacilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Corporate Office and Laboratory Facilities</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CorporateOfficeAndLaboratoryFacilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Corporate Office And Laboratory Facilities [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember" xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventMember" xlink:to="us-gaap_SubsequentEventMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:type="locator" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee Lease Description [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_LesseeLeaseDescriptionLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Description [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average remaining lease term</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Remaining Lease Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseRenewalTerm" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseRenewalTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Renewal term</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:to="us-gaap_LesseeOperatingLeaseRenewalTerm_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseRenewalTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Renewal Term</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease, existence of option to extend</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend" xlink:to="us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Existence Of Option To Extend</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average discount rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Discount Rate Percent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2021</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Next Twelve Months</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Two</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2025</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2026 and thereafter</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due After Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total future minimum lease payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less imputed interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Undiscounted Excess Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Present value of net minimum lease payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiability" xlink:to="us-gaap_OperatingLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityAbstract" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease liabilities:</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityAbstract" xlink:to="us-gaap_OperatingLeaseLiabilityAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Non-current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease liability</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LeaseExpirationYear" xlink:type="locator" xlink:label="nktx_LeaseExpirationYear" />
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lease expiration year.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LeaseExpirationYear" xlink:to="nktx_LeaseExpirationYear_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseRemainingLeaseTerm" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease term</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseRemainingLeaseTerm" xlink:to="us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Remaining Lease Term</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease expiration year</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Expiration Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseOptionToExtend" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseOptionToExtend" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee option to extend description</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseOptionToExtend" xlink:to="us-gaap_LesseeOperatingLeaseOptionToExtend_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Option To Extend</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LeaseExpirationMonthAndYear" xlink:type="locator" xlink:label="nktx_LeaseExpirationMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lease expiration month and year.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LeaseExpirationMonthAndYear" xlink:to="nktx_LeaseExpirationMonthAndYear_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseDescription" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseDescription" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease, description</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseDescription" xlink:to="us-gaap_LesseeOperatingLeaseDescription_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Description</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease expiration month and year</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LeaseExpirationMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Expiration Month And Year</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments" xlink:type="locator" xlink:label="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments" />
    <link:label xml:lang="en-US" xlink:label="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee operating lease lease not yet commenced minimum lease payments.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments" xlink:to="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease not yet commenced minimum lease payments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Lease Not Yet Commenced Minimum Lease Payments</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesTable" xlink:type="locator" xlink:label="us-gaap_LossContingenciesTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss Contingencies [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LossContingenciesTable" xlink:to="us-gaap_LossContingenciesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingencies [Table]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AgreementWithFinancialInstitutionMember" xlink:type="locator" xlink:label="nktx_AgreementWithFinancialInstitutionMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementWithFinancialInstitutionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Agreement with financial institution.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AgreementWithFinancialInstitutionMember" xlink:to="nktx_AgreementWithFinancialInstitutionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementWithFinancialInstitutionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Agreement with Financial Institution</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementWithFinancialInstitutionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Agreement With Financial Institution [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:type="locator" xlink:label="us-gaap_LossContingenciesLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss Contingencies [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingenciesLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingencies [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue" xlink:type="locator" xlink:label="us-gaap_GuaranteeObligationsCurrentCarryingValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GuaranteeObligationsCurrentCarryingValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities recorded for agreements</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GuaranteeObligationsCurrentCarryingValue" xlink:to="us-gaap_GuaranteeObligationsCurrentCarryingValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GuaranteeObligationsCurrentCarryingValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Guarantee Obligations Current Carrying Value</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate" xlink:type="locator" xlink:label="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate" />
    <link:label xml:lang="en-US" xlink:label="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Letter of credit notice period by financial institution before annual expiration date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate" xlink:to="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:type="locator" xlink:label="us-gaap_LettersOfCreditOutstandingAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LettersOfCreditOutstandingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Letters of credit outstanding amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LettersOfCreditOutstandingAmount" xlink:to="us-gaap_LettersOfCreditOutstandingAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LettersOfCreditOutstandingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Letters Of Credit Outstanding Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Letter of credit notice period by financial institution before annual expiration date</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LetterOfCreditNoticePeriodByFinancialInstitutionBeforeAnnualExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Letter Of Credit Notice Period By Financial Institution Before Annual Expiration Date</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LicenseAgreementUpfrontPayment" xlink:type="locator" xlink:label="nktx_LicenseAgreementUpfrontPayment" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementUpfrontPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement upfront payment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LicenseAgreementUpfrontPayment" xlink:to="nktx_LicenseAgreementUpfrontPayment_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments" xlink:type="locator" xlink:label="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments" />
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period shares issued upfront payments.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments" xlink:to="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AnnualLicenseMaintenanceFee" xlink:type="locator" xlink:label="nktx_AnnualLicenseMaintenanceFee" />
    <link:label xml:lang="en-US" xlink:label="nktx_AnnualLicenseMaintenanceFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Annual license maintenance fee.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AnnualLicenseMaintenanceFee" xlink:to="nktx_AnnualLicenseMaintenanceFee_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_PotentialMilestonePayments" xlink:type="locator" xlink:label="nktx_PotentialMilestonePayments" />
    <link:label xml:lang="en-US" xlink:label="nktx_PotentialMilestonePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Potential milestone payments.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_PotentialMilestonePayments" xlink:to="nktx_PotentialMilestonePayments_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_PercentageOfLicensorsRoyalties" xlink:type="locator" xlink:label="nktx_PercentageOfLicensorsRoyalties" />
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfLicensorsRoyalties_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of Licensors royalties.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_PercentageOfLicensorsRoyalties" xlink:to="nktx_PercentageOfLicensorsRoyalties_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_PercentageOfSublicensingIncome" xlink:type="locator" xlink:label="nktx_PercentageOfSublicensingIncome" />
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfSublicensingIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of sublicensing income.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_PercentageOfSublicensingIncome" xlink:to="nktx_PercentageOfSublicensingIncome_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LicenseAgreementTerm" xlink:type="locator" xlink:label="nktx_LicenseAgreementTerm" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement term.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LicenseAgreementTerm" xlink:to="nktx_LicenseAgreementTerm_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_FairValueOfCommonStockIssued" xlink:type="locator" xlink:label="nktx_FairValueOfCommonStockIssued" />
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfCommonStockIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value of common stock issued.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_FairValueOfCommonStockIssued" xlink:to="nktx_FairValueOfCommonStockIssued_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LicenseAgreementLineItems" xlink:type="locator" xlink:label="nktx_LicenseAgreementLineItems" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LicenseAgreementLineItems" xlink:to="nktx_LicenseAgreementLineItems_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LicenseAgreementTable" xlink:type="locator" xlink:label="nktx_LicenseAgreementTable" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LicenseAgreementTable" xlink:to="nktx_LicenseAgreementTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License Agreement [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement [Table]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember" xlink:type="locator" xlink:label="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">National University of Singapore and St. Jude Children&apos;s Research Hospital.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember" xlink:to="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NUS and St. Jude</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_NationalUniversityOfSingaporeAndStJudeChildrenSResearchHospitalMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">National University Of Singapore And St Jude Children S Research Hospital [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_LicenseAgreementMember" xlink:type="locator" xlink:label="nktx_LicenseAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_LicenseAgreementMember" xlink:to="nktx_LicenseAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License Agreement</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis" xlink:type="locator" xlink:label="srt_StatementScenarioAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_StatementScenarioAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Scenario [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="srt_ScenarioUnspecifiedDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="srt_ScenarioUnspecifiedDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scenario Unspecified [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AfterYearTwoMember" xlink:type="locator" xlink:label="nktx_AfterYearTwoMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_AfterYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">After year two.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AfterYearTwoMember" xlink:to="nktx_AfterYearTwoMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_AfterYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">After Year Two of the Agreement</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AfterYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">After Year Two [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis" xlink:type="locator" xlink:label="srt_ProductOrServiceAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_ProductOrServiceAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductOrServiceAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ProductOrServiceAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Product Or Service [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:type="locator" xlink:label="srt_ProductsAndServicesDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Product and Service</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ProductsAndServicesDomain" xlink:to="srt_ProductsAndServicesDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ProductsAndServicesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Products And Services [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LicenseAndMaintenanceMember" xlink:type="locator" xlink:label="us-gaap_LicenseAndMaintenanceMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LicenseAndMaintenanceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License Maintenance Fees</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LicenseAndMaintenanceMember" xlink:to="us-gaap_LicenseAndMaintenanceMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LicenseAndMaintenanceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License And Maintenance [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License Agreement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementUpfrontPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Upfront payment</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementUpfrontPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement Upfront Payment</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Upfront payment, shares issued</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockIssuedDuringPeriodSharesIssuedUpfrontPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Issued Upfront Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfCommonStockIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value of common stock issued</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_FairValueOfCommonStockIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Of Common Stock Issued</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AnnualLicenseMaintenanceFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Annual license maintenance fee</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AnnualLicenseMaintenanceFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Annual License Maintenance Fee</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PotentialMilestonePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Potential milestone payments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PotentialMilestonePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Potential Milestone Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfLicensorsRoyalties_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of licensors royalties</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfLicensorsRoyalties_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Licensors Royalties</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfSublicensingIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of sublicensing income</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfSublicensingIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Sublicensing Income</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License agreement term</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement Term</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment" xlink:type="locator" xlink:label="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment" />
    <link:label xml:lang="en-US" xlink:label="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Milestone payment upon completion of regulatory milestone related to the clinical development.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment" xlink:to="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Research and development costs</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Milestone payment</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_MilestonePaymentUponCompletionOfRegulatoryMilestoneRelatedToClinicalDevelopment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Milestone Payment Upon Completion Of Regulatory Milestone Related To Clinical Development</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanTable" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined Contribution Plan [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanTable" xlink:to="us-gaap_DefinedContributionPlanTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:type="locator" xlink:label="us-gaap_RetirementPlanTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retirement Plan Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retirement Plan Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:type="locator" xlink:label="us-gaap_RetirementPlanTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retirement Plan Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="us-gaap_RetirementPlanTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetirementPlanTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retirement Plan Type [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_KPlanMember" xlink:type="locator" xlink:label="nktx_KPlanMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_KPlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">401 (K) Plan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_KPlanMember" xlink:to="nktx_KPlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_KPlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">401 (K) Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_KPlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">K Plan [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanDisclosureLineItems" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanDisclosureLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Disclosure [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans" xlink:type="locator" xlink:label="us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined contribution plan, description</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans" xlink:to="us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Description Of Defined Contribution Pension And Other Postretirement Plans</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employer contribution, percent</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:to="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Employer Matching Contribution Percent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanCostRecognized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanCostRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expense contribution plan</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanCostRecognized" xlink:to="us-gaap_DefinedContributionPlanCostRecognized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanCostRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Cost Recognized</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeriesAConvertiblePreferredStockMember" xlink:type="locator" xlink:label="nktx_SeriesAConvertiblePreferredStockMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series A convertible preferred stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeriesAConvertiblePreferredStockMember" xlink:to="nktx_SeriesAConvertiblePreferredStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series A Convertible Preferred Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series A Convertible Preferred Stock [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transactions By Related Party [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="us-gaap_RelatedPartyDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeriesAFinancingInvestorsMember" xlink:type="locator" xlink:label="nktx_SeriesAFinancingInvestorsMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAFinancingInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series A financing investors.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeriesAFinancingInvestorsMember" xlink:to="nktx_SeriesAFinancingInvestorsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAFinancingInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series A Financing investors</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAFinancingInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series A Financing Investors [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="us-gaap_DebtInstrumentNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Name [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_GlaxoSmithKlineConvertibleNoteMember" xlink:type="locator" xlink:label="nktx_GlaxoSmithKlineConvertibleNoteMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_GlaxoSmithKlineConvertibleNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">GlaxoSmithKline convertible note.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_GlaxoSmithKlineConvertibleNoteMember" xlink:to="nktx_GlaxoSmithKlineConvertibleNoteMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_GlaxoSmithKlineConvertibleNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">GSK Convertible Note</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_GlaxoSmithKlineConvertibleNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Glaxo Smith Kline Convertible Note [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeriesAInvestorsMember" xlink:type="locator" xlink:label="nktx_SeriesAInvestorsMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series A investors.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeriesAInvestorsMember" xlink:to="nktx_SeriesAInvestorsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series A investors</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesAInvestorsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series A Investors [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeriesBConvertiblePromissoryNotesMember" xlink:type="locator" xlink:label="nktx_SeriesBConvertiblePromissoryNotesMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePromissoryNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series B convertible promissory notes.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeriesBConvertiblePromissoryNotesMember" xlink:to="nktx_SeriesBConvertiblePromissoryNotesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePromissoryNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series B Convertible Promissory Notes</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeriesBConvertiblePromissoryNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series B Convertible Promissory Notes [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RestatementAxis" xlink:type="locator" xlink:label="srt_RestatementAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_RestatementAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revision of Prior Period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RestatementAxis" xlink:to="srt_RestatementAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RestatementAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restatement [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:label="srt_RestatementDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revision of Prior Period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RestatementDomain" xlink:to="srt_RestatementDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RestatementDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restatement [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RestatementAdjustmentMember" xlink:type="locator" xlink:label="srt_RestatementAdjustmentMember" />
    <link:label xml:lang="en-US" xlink:label="srt_RestatementAdjustmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Previously Recorded</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RestatementAdjustmentMember" xlink:to="srt_RestatementAdjustmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RestatementAdjustmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restatement Adjustment [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_StockPurchaseAgreementMember" xlink:type="locator" xlink:label="nktx_StockPurchaseAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_StockPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock purchase agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_StockPurchaseAgreementMember" xlink:to="nktx_StockPurchaseAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_StockPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Purchase Agreement</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_StockPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Purchase Agreement [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalUnitsAuthorized" xlink:type="locator" xlink:label="us-gaap_CapitalUnitsAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CapitalUnitsAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Capital stock, shares authorized</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CapitalUnitsAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Capital Units Authorized</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_PercentageOfOutstandingConvertibleNotesConvertedIntoConvertiblePreferredStock" xlink:type="locator" xlink:label="nktx_PercentageOfOutstandingConvertibleNotesConvertedIntoConvertiblePreferredStock" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Stock issued and sold</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible preferred stock price per share</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Convertible Conversion Price1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible notes outstanding shares converted into convertible preferred stock</link:label>
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    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfOutstandingConvertibleNotesConvertedIntoConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of outstanding convertible notes into convertible preferred stock</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Convertible Beneficial Conversion Feature</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ConvertibleNotesAccruedInterestPerYear" xlink:type="locator" xlink:label="nktx_ConvertibleNotesAccruedInterestPerYear" />
    <link:label xml:lang="en-US" xlink:label="nktx_ConvertibleNotesAccruedInterestPerYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Convertible notes accrued interest per year.</link:label>
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    <link:loc xlink:href="nktx-20201231.xsd#nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock" xlink:type="locator" xlink:label="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock" />
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of convertible notes automatically convert into Series B convertible preferred stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock" xlink:to="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of convertible promissory notes issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Conversion Of Convertible Securities Net Of Adjustments</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ConvertibleNotesAccruedInterestPerYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible notes accrued interest per year</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ConvertibleNotesAccruedInterestPerYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Convertible Notes Accrued Interest Per Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTerm" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible notes original maturity date from issuance date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentTerm" xlink:to="us-gaap_DebtInstrumentTerm_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Term</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of convertible notes automatically convert into Series B convertible preferred stock price per share</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PercentageOfConvertibleNotesAutomaticallyConvertIntoSeriesBConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Convertible Notes Automatically Convert Into Series B Convertible Preferred Stock</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod" xlink:type="locator" xlink:label="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod" />
    <link:label xml:lang="en-US" xlink:label="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Amortization Term of interest expense using effective interest method.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod" xlink:to="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleDebtFairValueDisclosures" xlink:type="locator" xlink:label="us-gaap_ConvertibleDebtFairValueDisclosures" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConvertibleDebtFairValueDisclosures_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative instrument</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertibleDebtFairValueDisclosures" xlink:to="us-gaap_ConvertibleDebtFairValueDisclosures_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConvertibleDebtFairValueDisclosures_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Convertible Debt Fair Value Disclosures</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization term of interest expense using effective interest method</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AmortizationTermOfInterestExpenseUsingEffectiveInterestMethod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Term Of Interest Expense Using Effective Interest Method</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument" xlink:type="locator" xlink:label="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument" />
    <link:label xml:lang="en-US" xlink:label="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in conversion benefit resulted in adjustment to derivative instrument.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument" xlink:to="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in conversion benefit resulted in adjustment to derivative instrument</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ChangeInConversionBenefitResultedInAdjustmentToDerivativeInstrument_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Conversion Benefit Resulted In Adjustment To Derivative Instrument</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel">Loss on extinguishment of debt</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpenseDebtExcludingAmortization" xlink:type="locator" xlink:label="us-gaap_InterestExpenseDebtExcludingAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseDebtExcludingAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest expense related to stated interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpenseDebtExcludingAmortization" xlink:to="us-gaap_InterestExpenseDebtExcludingAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseDebtExcludingAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense Debt Excluding Amortization</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:type="locator" xlink:label="us-gaap_AmortizationOfFinancingCosts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Effective-interest relation to debt discounts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfFinancingCosts" xlink:to="us-gaap_AmortizationOfFinancingCosts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Of Financing Costs</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Annual effective-interest rates</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Interest Rate Effective Percentage</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone" xlink:type="locator" xlink:label="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone" />
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Temporary equity stock issuable upon achievement of milestone</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone" xlink:to="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock" xlink:type="locator" xlink:label="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock" />
    <link:label xml:lang="en-US" xlink:label="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Gross proceeds from issuance of convertible preferred stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock" xlink:to="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ConversionOfStockSharesConvertible" xlink:type="locator" xlink:label="nktx_ConversionOfStockSharesConvertible" />
    <link:label xml:lang="en-US" xlink:label="nktx_ConversionOfStockSharesConvertible_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Conversion of stock shares convertible.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ConversionOfStockSharesConvertible" xlink:to="nktx_ConversionOfStockSharesConvertible_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of convertible preferred stock sold and issued during the period</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityStockIssuableUponAchievementOfMilestone_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Stock Issuable Upon Achievement Of Milestone</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross proceed from convertible preferred stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_GrossProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Gross Proceeds From Issuance Of Convertible Preferred Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ConversionOfStockSharesConvertible_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares converted into shares</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ConversionOfStockSharesConvertible_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Conversion Of Stock Shares Convertible</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Sale of preferred stock, net of issuance costs, Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Conversion of preferred stock, Shares</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Number of shares converted into shares</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Estimated fair value of preferred stock purchase right liability</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveTerseLabel">Change in fair value of purchase right liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock public offering price</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockPricePerShare" xlink:to="us-gaap_SaleOfStockPricePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Of Stock Price Per Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCash" xlink:type="locator" xlink:label="us-gaap_DividendsCash" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsCash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash dividends declared or paid</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsCash" xlink:to="us-gaap_DividendsCash_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsCash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Cash</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CommonStockNumberOfVotingRightsForEachShare" xlink:type="locator" xlink:label="nktx_CommonStockNumberOfVotingRightsForEachShare" />
    <link:label xml:lang="en-US" xlink:label="nktx_CommonStockNumberOfVotingRightsForEachShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock number of voting rights for each share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CommonStockNumberOfVotingRightsForEachShare" xlink:to="nktx_CommonStockNumberOfVotingRightsForEachShare_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockVotingRights" xlink:type="locator" xlink:label="us-gaap_CommonStockVotingRights" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockVotingRights_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, voting rights</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockVotingRights" xlink:to="us-gaap_CommonStockVotingRights_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockVotingRights_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Voting Rights</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CommonStockNumberOfVotingRightsForEachShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock entitled, number of vote for each share</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CommonStockNumberOfVotingRightsForEachShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Number Of Voting Rights For Each Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameDomain" xlink:to="us-gaap_PlanNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_TwoThousandFifteenEquityIncentivePlanMember" xlink:type="locator" xlink:label="nktx_TwoThousandFifteenEquityIncentivePlanMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand fifteen equity incentive plan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_TwoThousandFifteenEquityIncentivePlanMember" xlink:to="nktx_TwoThousandFifteenEquityIncentivePlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2015 Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Fifteen Equity Incentive Plan [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_TwoThousandTwentyPerformanceIncentivePlanMember" xlink:type="locator" xlink:label="nktx_TwoThousandTwentyPerformanceIncentivePlanMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand twenty performance incentive plan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_TwoThousandTwentyPerformanceIncentivePlanMember" xlink:to="nktx_TwoThousandTwentyPerformanceIncentivePlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020 Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Twenty Performance Incentive Plan [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020 Employee Stock Purchase Plan</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockMember" xlink:to="us-gaap_EmployeeStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_AwardTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Stock Options</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockMember" xlink:to="us-gaap_RestrictedStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_SeparationAndReleaseAgreementMember" xlink:type="locator" xlink:label="nktx_SeparationAndReleaseAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeparationAndReleaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Separation and release agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_SeparationAndReleaseAgreementMember" xlink:to="nktx_SeparationAndReleaseAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_SeparationAndReleaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Separation and Release Agreement</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_SeparationAndReleaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Separation And Release Agreement [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:type="locator" xlink:label="srt_TitleOfIndividualAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_TitleOfIndividualAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title of Individual</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_TitleOfIndividualAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Title Of Individual [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="locator" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title of Individual</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Title Of Individual With Relationship To Entity [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ChiefFinancialOfficerMember" xlink:type="locator" xlink:label="srt_ChiefFinancialOfficerMember" />
    <link:label xml:lang="en-US" xlink:label="srt_ChiefFinancialOfficerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Matthew Plunkett</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ChiefFinancialOfficerMember" xlink:to="srt_ChiefFinancialOfficerMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ChiefFinancialOfficerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Chief Financial Officer [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Shares Issued In Period</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear" xlink:type="locator" xlink:label="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase in share limit as percentage of outstanding shares of common stock on last trading day in prior year.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear" xlink:to="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of common stock authorized for issuance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in share limit as percentage of outstanding shares of common stock on last trading day in prior year</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_IncreaseInShareLimitAsPercentageOfOutstandingSharesOfCommonStockOnLastTradingDayInPriorYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase In Share Limit As Percentage Of Outstanding Shares Of Common Stock On Last Trading Day In Prior Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of awards granted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:type="locator" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Number of common stock available for issuance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Capital Shares Reserved For Future Issuance</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember" xlink:type="locator" xlink:label="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand twenty performance incentive and two thousand fifteen equity incentive plan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember" xlink:to="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020 Plan and 2015 Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentiveAndTwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Twenty Performance Incentive And Two Thousand Fifteen Equity Incentive Plan [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Number of shares, outstanding beginning balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares, granted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of shares, exercised</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of shares, forfeited</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Number of shares, outstanding ending balance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares, exercisable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of shares, vested and expected to vest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average exercise price, granted</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average exercise price, exercised</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average exercise price, forfeited</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Weighted-average exercise price, outstanding ending balance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average exercise price, exercisable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average exercise price, vested and expected to vest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average remaining contractual term (in years), outstanding balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average remaining contractual term (in years), exercisable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average remaining contractual term (in years), vested and expected to vest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate intrinsic value, outstanding balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate intrinsic value, exercisable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate intrinsic value, vested and expected to vest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average grant-date fair value of stock option grants per share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intrinsic value of options exercised</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair value of options vested</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" xlink:type="locator" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" />
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award offering period.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" xlink:to="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum percentage of employee compensation eligible for plan</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Maximum Employee Subscription Rate</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Offering period</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Offering Period</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commons stock purchase price as percentage of fair value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Purchase Price Of Common Stock Percent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:type="locator" xlink:label="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares subject to repurchase</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:to="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchase Program Number Of Shares Authorized To Be Repurchased</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Other long-term liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock Options Granted and Outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOptionMember" xlink:to="us-gaap_EmployeeStockOptionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Option [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_TwoThousandTwentyPerformanceIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Reserved for Future Equity Award Grants</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Reserved for Future ESPP Issuances</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock reserved for future issuance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_IncomeStatementLocationDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpenseMember" xlink:to="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research And Development Expense [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">General and Administrative</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GeneralAndAdministrativeExpenseMember" xlink:to="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">General And Administrative Expense [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share-based compensation expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation cost, expected to be recognized over weighted average remaining service period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_AgreementExecutionDate" xlink:type="locator" xlink:label="nktx_AgreementExecutionDate" />
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementExecutionDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Agreement execution date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_AgreementExecutionDate" xlink:to="nktx_AgreementExecutionDate_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate" xlink:type="locator" xlink:label="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate" />
    <link:label xml:lang="en-US" xlink:label="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Period within severance benefits payable after termination date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate" xlink:to="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Share-based compensation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeveranceCosts1" xlink:type="locator" xlink:label="us-gaap_SeveranceCosts1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SeveranceCosts1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Severance benefits expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeveranceCosts1" xlink:to="us-gaap_SeveranceCosts1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SeveranceCosts1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Severance Costs1</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementExecutionDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Agreement execution date</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_AgreementExecutionDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Agreement Execution Date</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Period in which severance benefits payable after termination date</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_PeriodWithinSeveranceBenefitsPayableAfterTerminationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Period Within Severance Benefits Payable After Termination Date</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue" xlink:type="locator" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue" />
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award fair value assumptions common stock fair value.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue" xlink:to="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock fair value</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCommonStockFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Common Stock Fair Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risk-free interest rate, minimum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Minimum</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risk-free interest rate, maximum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Maximum</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected volatility, minimum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Minimum</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected volatility, maximum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Maximum</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected term (in years)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected dividend yield</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_DividendsShareBasedCompensation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends issued for options</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsShareBasedCompensation" xlink:to="us-gaap_DividendsShareBasedCompensation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Share Based Compensation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends expected to be issued over life of options</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Estimated dividend yield</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncomeTaxesLineItems" xlink:type="locator" xlink:label="nktx_IncomeTaxesLineItems" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income taxes.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_IncomeTaxesLineItems" xlink:to="nktx_IncomeTaxesLineItems_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncomeTaxesTable" xlink:type="locator" xlink:label="nktx_IncomeTaxesTable" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income taxes.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_IncomeTaxesTable" xlink:to="nktx_IncomeTaxesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Taxes [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Taxes [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:type="locator" xlink:label="us-gaap_IncomeTaxAuthorityDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Tax Authority</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_IncomeTaxAuthorityDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Authority [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DomesticCountryMember" xlink:type="locator" xlink:label="us-gaap_DomesticCountryMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DomesticCountryMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DomesticCountryMember" xlink:to="us-gaap_DomesticCountryMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DomesticCountryMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Domestic Country [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:type="locator" xlink:label="us-gaap_StateAndLocalJurisdictionMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">California State</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StateAndLocalJurisdictionMember" xlink:to="us-gaap_StateAndLocalJurisdictionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">State And Local Jurisdiction [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxPeriodAxis" xlink:type="locator" xlink:label="us-gaap_TaxPeriodAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxPeriodAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxPeriodAxis" xlink:to="us-gaap_TaxPeriodAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxPeriodAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Period [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:type="locator" xlink:label="us-gaap_TaxPeriodDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxPeriodDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxPeriodDomain" xlink:to="us-gaap_TaxPeriodDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxPeriodDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Period [Domain]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ExpirationYearOneMember" xlink:type="locator" xlink:label="nktx_ExpirationYearOneMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Expiration year one.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ExpirationYearOneMember" xlink:to="nktx_ExpirationYearOneMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2035</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Expiration Year One [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_ExpirationYearTwoMember" xlink:type="locator" xlink:label="nktx_ExpirationYearTwoMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Expiration year two.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_ExpirationYearTwoMember" xlink:to="nktx_ExpirationYearTwoMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2036</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_ExpirationYearTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Expiration Year Two [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_CarryForwardIndefinitelyMember" xlink:type="locator" xlink:label="nktx_CarryForwardIndefinitelyMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_CarryForwardIndefinitelyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Carry forward indefinitely.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_CarryForwardIndefinitelyMember" xlink:to="nktx_CarryForwardIndefinitelyMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_CarryForwardIndefinitelyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Carry Forward Indefinitely</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_CarryForwardIndefinitelyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Carry Forward Indefinitely [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:type="locator" xlink:label="us-gaap_TaxCreditCarryforwardAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Credit Carryforward</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxCreditCarryforwardAxis" xlink:to="us-gaap_TaxCreditCarryforwardAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:type="locator" xlink:label="us-gaap_TaxCreditCarryforwardNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax Credit Carryforward, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxCreditCarryforwardNameDomain" xlink:to="us-gaap_TaxCreditCarryforwardNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward Name [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchMember" xlink:type="locator" xlink:label="us-gaap_ResearchMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and Development Credit Carry Forwards</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchMember" xlink:to="us-gaap_ResearchMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ResearchMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research [Member]</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember" xlink:type="locator" xlink:label="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember" />
    <link:label xml:lang="en-US" xlink:label="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Net operating loss and tax credit carryforwards to offset.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember" xlink:to="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net Operating Loss and Tax Credit Carryforwards to Offset</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_NetOperatingLossAndTaxCreditCarryforwardsToOffsetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Operating Loss And Tax Credit Carryforwards To Offset [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Taxes [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Taxes [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Provision or benefit for income taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Expense Benefit</link:label>
    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncomeTaxReconciliationPermanentItems" xlink:type="locator" xlink:label="nktx_IncomeTaxReconciliationPermanentItems" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxReconciliationPermanentItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income tax reconciliation permanent items.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_IncomeTaxReconciliationPermanentItems" xlink:to="nktx_IncomeTaxReconciliationPermanentItems_lbl" />
    <link:loc xlink:href="nktx-20201231.xsd#nktx_IncomeTaxReconciliationChangeInFairValueOfDerivativeLiability" xlink:type="locator" xlink:label="nktx_IncomeTaxReconciliationChangeInFairValueOfDerivativeLiability" />
    <link:label xml:lang="en-US" xlink:label="nktx_IncomeTaxReconciliationChangeInFairValueOfDerivativeLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Income tax reconciliation change in fair value of derivative liability.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nktx_IncomeTaxReconciliationChangeInFairValueOfDerivativeLiability" xlink:to="nktx_IncomeTaxReconciliationChangeInFairValueOfDerivativeLiability_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income tax benefit at statutory rates</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:to="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" />
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