0000950170-24-056980 | 10-Q | XBRL Viewer

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CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses
Research and development	$ 25,237	$ 26,135
General and administrative	7,525	8,178
Total operating expenses	32,762	34,313
Loss from operations	(32,762)	(34,313)
Other income, net:
Interest income	3,246	3,465
Other (expense) income, net	(2)	33
Total other income, net	3,244	3,498
Net loss	(29,518)	(30,815)
Other comprehensive loss:
Net unrealized (loss) gain on investments	(135)	505
Comprehensive loss	$ (29,653)	$ (30,310)
Net loss per share, basic	$ (0.58)	$ (0.63)
Net loss per share, diluted	$ (0.58)	$ (0.63)
Weighted average shares used to compute net loss per share, basic	50,682,469	48,921,326
Weighted average shares used to compute net loss per share, diluted	50,682,469	48,921,326

Leases

3 Months Ended

Mar. 31, 2024

Leases [Abstract]

Leases

6. Leases

The Company has operating leases for its current corporate offices, laboratories, manufacturing facilities, and dedicated space in a vivarium in South San Francisco, California. Rent expense was $2.7 million for the three months ended March 31, 2024, and 2023. The total cash paid for the three months ended March 31, 2024 for operating leases included in the operating cash flows was $3.3 million, inclusive of $3.1 million of rent payments and $0.2 million of tenant improvement allowance repayment, as compared to net cash received of $5.8 million for the three months ended March 31, 2023, comprised of $7.8 million cash received for the tenant improvement allowance reimbursement less $2.0 million of rent payment. The weighted average remaining lease term was 9.6 years for the corporate office, laboratory space leases, and additional facility as of March 31, 2024. The weighted average discount rate was 9.8% as of March 31, 2024.

Initial Lease Agreement

In May 2018, the Company entered into a lease agreement for corporate office and laboratory space located in South San Francisco, California with an expiration date in May 2025 (the "Initial Lease Agreement"). In April 2019, the Company executed the first amendment to the Initial Lease Agreement for additional corporate space, laboratory space and manufacturing capabilities. In May 2020, the Company executed the second amendment to the Initial Lease Agreement for additional corporate space and laboratory space in the same building. The lease for this additional space commenced in January 2021. In January 2021, the Company signed a third amendment to the Initial Lease Agreement for additional space in the same building. The lease amendment for this additional space commenced in April 2021 and expired in March 2024. In October 2021, the Company signed a fourth amendment to the Initial Lease Agreement for additional space in the same building, that commenced in April 2022. All space leased under the Initial Lease Agreement, together with the first amendment, second amendment, and fourth amendment to the Initial Lease Agreement, has a lease term through July 31, 2030, with an option to extend the lease for an additional seven-year term. This lease extension option was not considered in the right-of-use assets or the lease liability as the Company did not consider it reasonably certain the option would be exercised.

Additional Lease Agreement

In July 2021, the Company entered into an additional lease agreement for corporate office, manufacturing and laboratory space located in South San Francisco, California with an expiration date approximately twelve years after the lease commencement date (as amended from time to time, the "Additional Lease Agreement"). The lease for this additional space and the Company's obligation to pay rent commenced in January 2022. In addition to base rent, the Company is responsible for payment of direct expenses, which include operating, insurance and tax expenses. The Additional Lease Agreement provided for certain tenant improvement allowances that were fully utilized and reimbursed to the Company, and an additional tenant improvement allowance to be utilized at the option of the Company. In June 2023, the Company entered into an amendment to utilize the additional tenant improvement allowance of $4.4 million and under this amendment the Company is required to repay the tenant improvement costs in equal monthly payments at an annual rate of 8.5% over the remainder of the lease term starting in July 2023.

Maturities of operating lease liabilities under existing operating leases as of March 31, 2024 were as follows (in thousands):


Year ending December 31,	Amount
2024 (remaining nine months)	$	9,545
2025		13,027
2026		13,462
2027		13,912
2028		14,378
2029 and thereafter		72,876
Total undiscounted future minimum lease payments		137,200
Less imputed interest		(50,026	)
Total operating lease liabilities	$	87,174
Operating lease liabilities:
Current		6,078
Non-current		81,096
Total lease liability	$	87,174

Lease Impairment

The Company tests long-lived assets for recoverability whenever events or changes in circumstances suggest that the carrying value of an asset or group of assets may not be recoverable. Beginning in the second quarter of 2023, the Company started to market for sublease portions of the Company's leased corporate office space in South San Francisco. As a result of these plans, the Company reviewed these spaces for impairment. As part of the impairment evaluation of the spaces being marketed for sublease, the Company compared the estimated undiscounted income for the marketed sublease spaces to the net book value of the related long-term assets, which include right-of-use assets and certain property and equipment, primarily for leasehold improvements (collectively, "Sublease Asset Group"). The Company estimated potential sublease income using market participant assumptions, which the Company evaluated based on current real estate trends and market conditions. For the Sublease Asset Group, the Company determined that the respective right-of-use assets had net carrying values that exceeded their estimated undiscounted future cash flows. Accordingly, the Company then estimated the fair value of the Sublease Asset Group based on its discounted cash flows. The carrying value of the Sublease Asset Group exceeded its fair values and, as a result, the Company recorded a right-of-use asset impairment of $4.1 million for the six months ended June 30, 2023. The impairment is recorded within general and administrative expenses in the condensed statements of operations and comprehensive loss. There was no additional impairment recorded for the three months ended March 31, 2024.

Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements as of March 31, 2024 and for the three months ended March 31, 2024 and 2023 have been prepared in accordance with U.S. generally accepted accounting principle ("U.S. GAAP") for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act, as amended. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows for the periods presented. The results for the three months ended March 31, 2024 are not necessarily indicative of the results expected for the full year or any subsequent interim period. The condensed balance sheet as of December 31, 2023 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2023, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed by the Company with the SEC on March 21, 2024.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to preclinical studies and clinical trial accruals, fair value of assets and liabilities, impairment of assets, leases, share-based compensation and income taxes. Management bases its estimates on historical experience, knowledge of current events and actions it may undertake in the future that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares and pre-funded warrants outstanding for the period, without consideration of potential dilutive securities. Pre-funded warrants are considered outstanding for the purposes of computing basic and diluted net loss per share because shares may be issued for little or no additional consideration and are fully vested and exercisable after the original issuance date of the pre-funded warrants. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares and pre-funded warrants plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include unvested common stock, outstanding stock options and restricted stock units under the Company’s equity incentive plans, have been excluded from the computation of diluted net loss per share as they would be antidilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.
Long-Lived Asset Impairment	Long-Lived Asset Impairment The Company assesses the impairment of long-lived assets whenever events or changes in business circumstances indicate that the carrying amounts of the asset or group of assets may not be fully recoverable. In the case of property and equipment and right-of-use assets for the Company's leases, the Company determines whether there has been an impairment by comparing the carrying value of the group of assets to the anticipated undiscounted net future cash flows associated with the group of assets. If such cash flows are less than the carrying value, the Company writes down the group of assets to its fair value, which may be measured as anticipated net cash flows associated with the group of assets, discounted at a rate that the Company believes a market participant would utilize to reflect the risks associated with the cash flows, such as credit risk. See Note 6 for additional information regarding the prior year impairment charge the Company recorded in connection with its leased facilities.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2023, the Financial Accounting Standard Board ("FASB") issued Accounting Standards Update ("ASU") No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires disclosure of incremental segment information on an interim and annual basis. This ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal periods beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. The Company is currently evaluating the impact of the guidance on the financial statements and disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). ASU 2023-09 is intended to enhance the transparency and decision usefulness of income tax disclosures. The amendments in ASU 2023-09 address investor requests for enhanced income tax information primarily through changes to the rate reconciliation and income taxes paid information. ASU 2023-09 will be effective for us in the annual period beginning January 1, 2025, though early adoption is permitted. The Company is currently evaluating the presentational effect that ASU 2023-09 will have on its financial statements. In August 2020, the FASB issued ASU No. 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 740-20) and Derivative and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”), which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. ASU 2020-06 also removes certain settlement conditions that are required for equity-linked contracts to qualify for the derivative scope exception, and it simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for the Company beginning on January 1, 2024. The adoption of ASU 2020-06 does not have a material impact on the financial position, results of operations or cash flows of the Company. There were no other significant updates to the recently issued accounting standards other than as disclosed herewith. Although there are several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Fair Value of Financial Instruments - Summary of Fair Value of Financial Instrument (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets:
Money market funds	$ 249,867	$ 30,751
Total short-term investments	187,109	217,149
Total long-term investments	9,814
Total	446,790	247,900
Commercial Paper
Assets:
Total short-term investments	28,676	38,197
Corporate Debt Securities
Assets:
Total short-term investments	38,843	40,609
Total long-term investments	9,814
U.S. Government securities
Assets:
Total short-term investments	119,590	138,343
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Money market funds	249,867	30,751
Total	249,867	30,751
Significant Other Observable Inputs (Level 2)
Assets:
Total short-term investments	187,109	217,149
Total long-term investments	9,814
Total	196,923	217,149
Significant Other Observable Inputs (Level 2) \| Commercial Paper
Assets:
Total short-term investments	28,676	38,197
Significant Other Observable Inputs (Level 2) \| Corporate Debt Securities
Assets:
Total short-term investments	38,843	40,609
Total long-term investments	9,814
Significant Other Observable Inputs (Level 2) \| U.S. Government securities
Assets:
Total short-term investments	$ 119,590	$ 138,343

Leases - Additional Information (Details) - USD ($)	1 Months Ended					3 Months Ended		6 Months Ended
Leases - Additional Information (Details) - USD ($)	Jun. 30, 2023	Oct. 31, 2021	Jan. 31, 2021	May 31, 2020	May 31, 2018	Mar. 31, 2024	Mar. 31, 2023	Jun. 30, 2023	Jul. 31, 2021
Lessee Lease Description [Line Items]
Rent expense						$ 2,700,000	$ 2,700,000
Weighted-average remaining lease term						9 years 7 months 6 days
Cash paid for operating leases						$ 3,300,000	5,800,000
Weighted-average discount rate						9.80%
Lessee, operating lease, term of contract									12 years
Additional tenant improvement allowances	$ 4,400,000
Tenant improvement costs in equal monthly payments annual rate	8.50%
Tenant improvement allowance repayment						$ 200,000	7,800,000
Right-of-use asset impairment						0		$ 4,100,000
Rent payments						$ 3,100,000	$ 2,000,000
Third amendment
Lessee Lease Description [Line Items]
Operating lease, description						The lease amendment for this additional space commenced in April 2021 and expired in March 2024.
Lease expiration month and year			2024-03
Initial Lease Agreement
Lessee Lease Description [Line Items]
Lease expiration year					2025
Operating lease, existence of option to extend		true		true
Corporate Office and Laboratory Space \| Initial Lease Agreement
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend					true
Lessee option to extend description						In April 2019, the Company executed the first amendment to the Initial Lease Agreement for additional corporate space, laboratory space and manufacturing capabilities.
Renewal term					7 years

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 2.3	$ 0.8

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Unit Activity - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, outstanding beginning balance	594,768
Number of shares, granted	775,153
Number of shares, Vested	(133,595)
Number of shares, forfeited	(19,509)
Number of shares, outstanding ending balance	1,216,817		594,768
Weighted-average grant date fair value per share, outstanding beginning balance	$ 8.16
Weighted-average grant date fair value per share, granted	6.01	$ 5.57
Weighted-average grant date fair value per share, Vested	7.45
Weighted-average grant date fair value per share, Forfeited	7.22
Weighted-average grant date fair value per share, outstanding ending balance	$ 6.88		$ 8.16
Weighted-average remaining contractual term (in years), outstanding ending balance	2 years		1 year 4 months 24 days

Income Taxes

3 Months Ended

Mar. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

There was no provision for income taxes recorded during the three months ended March 31, 2024 and 2023. The Company’s deferred tax assets continue to be fully offset by a valuation allowance.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Pre-funded warrant	Common Stock	Common Stock Pre-funded warrant	Additional Paid-In Capital	Additional Paid-In Capital Pre-funded warrant	Accumulated Other Comprehensive Gain/(Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2022	$ 372,207		$ 5		$ 690,814		$ (679)	$ (317,933)
Beginning Balance, Shares at Dec. 31, 2022			48,877,806
Vesting of shares of common stock subject to repurchase	2				2
Vesting of shares of common stock subject to repurchase, Shares			395
Issuance of common stock upon exercise of stock options	1				1
Issuance of common stock upon exercise of stock options, Shares			253
Issuance of common stock upon vesting of restricted stock units, Shares			50,469
Issuance of common stock upon employee stock purchase plan	4,746				4,746
Unrealized gain (loss) on investments	505						505
Net loss	(30,815)							(30,815)
Ending Balance at Mar. 31, 2023	346,646		$ 5		695,563		(174)	(348,748)
Ending Balance, Shares at Mar. 31, 2023			48,928,923
Beginning Balance at Dec. 31, 2023	273,285		$ 5		708,706		8	(435,434)
Beginning Balance, Shares at Dec. 31, 2023			49,181,295
Issuance of common stock upon exercise of stock options	$ 578				578
Issuance of common stock upon exercise of stock options, Shares	128,671		128,671
Issuance of common stock, net of issuance costs		$ 225,073		$ 2		$ 225,071
Issuance of common stock, net of issuance costs, Shares			0	21,010,000
Issuance of common stock upon vesting of restricted stock units, Shares			133,595
Share-based compensation expense	$ 4,368				4,368
Unrealized gain (loss) on investments	(135)						(135)
Net loss	(29,518)							(29,518)
Ending Balance at Mar. 31, 2024	$ 473,651		$ 7		$ 938,723		$ (127)	$ (464,952)
Ending Balance, Shares at Mar. 31, 2024			70,453,561

Stockholders' Equity - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 4,368	$ 4,746
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	2,200	2,082
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 2,168	$ 2,664

Commitments and Contingencies

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments & Contingencies

Guarantee Agreement

The Company has agreements whereby it indemnifies its officers and directors for certain events or occurrences while the officer or director is, or was, serving at the Company’s request in such capacity. The term of the indemnification period is for the officer’s or director’s lifetime. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited; however, the Company has a director and officer insurance policy that limits its exposure and enables the Company to recover a portion of any future amounts under certain circumstances and subject to deductibles and exclusions. The Company had no liabilities recorded for these agreements as of March 31, 2024, and December 31, 2023.

Letters of Credit

The Company has $2.7 million in letter of credit agreements with a financial institution that are used as collateral for the Company’s corporate headquarters’ operating leases. The letters of credit automatically renew annually without amendment unless cancelled by the financial institutions within 30 to 60 days of the annual expiration date. The letters of credit are presented as restricted cash in the condensed balance sheet.

Contingencies

The Company, from time to time, may be involved in litigation arising in the ordinary course of business. The Company assesses its potential liability in such situations by analyzing potential outcomes, assuming various litigation, regulatory and settlement strategies. If the Company determines a loss is probable and its amount can be reasonably estimated, the Company accrues an amount equal to the estimated loss. No losses and no provision for a loss contingency have been recorded to date.

Purchase Commitments

The Company enters into contracts in the normal course of business for clinical trials, preclinical studies, manufacturing and other services and products for operating purposes. These contracts generally provide for termination following a certain period after notice and therefore the Company believes that non-cancelable obligations under these agreements are not material.

CRISPR Collaboration Agreement - Additional Information (Details) - Research Collaboration Agreement		3 Months Ended
	May 05, 2021 CrisprCas9	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)
Development and Regulatory Approval Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reduction of research and development expense resulting from partial reimbursement		$ 100,000	$ 900,000
Receivable under research cost sharing provision		$ 100,000
Potential future payments		totaling less than mid-twenty million dollars
Amount paid under the agreement		$ 0
Amounts owed under the agreement		$ 0
NK Cell Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of non-exclusive rights to gene editing targets licenses received \| CrisprCas9	4
NK Cell Products \| Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of non-exclusive rights to gene editing targets \| CrisprCas9	1
Specified TA \| Development and Regulatory Approval Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential future payments		totaling less than high-forty million dollars

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (29,518)	$ (30,815)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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+ Details

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net is comprised of the following (in thousands):


	March 31, 2024			December 31, 2023
Leasehold improvements	$	66,618		$	66,618
Furniture and fixtures		746			745
Research equipment		15,430			14,298
Computers and software		404			404
Construction in progress		9,273			8,954
Total property and equipment, gross		92,471			91,019
Less accumulated depreciation and amortization		(13,949	)		(11,693	)
Total property and equipment, net	$	78,522		$	79,326

Schedule of Accrued Other Current Liabilities

Accrued other current liabilities are comprised of the following (in thousands):


	March 31, 2024		December 31, 2023
Accrued compensation	$	3,774	$	6,722
Accrued research and development costs		7,452		5,845
Accrued property and equipment		91		174
Accrued stock issuance costs		615		—
Other accrued and current liabilities		1,002		855
Total accrued and other liabilities	$	12,934	$	13,596

Fair Value of Financial Instruments - Schedule of Short-term Investments Accounted as Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 197,050	$ 217,141
Available for sale securities, Unrealized Losses	(136)	(69)
Available for sale securities, Unrealized Gains	9	77
Available for sale securities,Estimated Fair Value	196,923	217,149
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	38,863	40,602
Available for sale securities, Unrealized Losses	(25)	(11)
Available for sale securities, Unrealized Gains	5	18
Available for sale securities,Estimated Fair Value	$ 38,843	$ 40,609
Corporate Debt Securities \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 9,835
Available for sale securities, Unrealized Losses	(21)
Available for sale securities,Estimated Fair Value	$ 9,814
Corporate Debt Securities \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 28,684	$ 38,198
Available for sale securities, Unrealized Losses	(8)	(2)
Available for sale securities, Unrealized Gains		1
Available for sale securities,Estimated Fair Value	$ 28,676	$ 38,197
Commercial Paper \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year
U.S. Government securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 119,668	$ 138,341
Available for sale securities, Unrealized Losses	(82)	(56)
Available for sale securities, Unrealized Gains	4	58
Available for sale securities,Estimated Fair Value	$ 119,590	$ 138,343
U.S. Government securities \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss Per Share

The following tables summarize the computation of the basic and diluted net loss per share (in thousands except share and per share data):


	Three Months Ended March 31,
	2024			2023
Numerator:
Net loss	$	(29,518	)	$	(30,815	)
Denominator:
Weighted average common shares outstanding		50,517,632			48,921,535
Less: weighted average unvested common stock issued upon early exercise of common stock options		—			(209	)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants		164,837			—
Weighted average shares used to compute net loss per share, basic and diluted		50,682,469			48,921,326
Net loss per share, basic and diluted	$	(0.58	)	$	(0.63	)

Summarizes the Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share

The following table summarizes the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be antidilutive:


	As of March 31,
	2024		2023
Common stock options		8,261,949		6,820,096
Restricted stock units		1,216,817		799,930
Unvested common stock upon early exercise of common stock options		—		113
		9,478,766		7,620,139

Organization and Description of Business

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Description of Business

1. Organization and Description of Business

Description of the Business

Nkarta, Inc. ("Nkarta" or the "Company") was incorporated in the State of Delaware in July 2015. The Company is a biopharmaceutical company developing engineered natural killer ("NK") cell therapies to treat cancer and autoimmune disease. The Company is focused on leveraging the natural potent power of NK cells to identify and kill abnormal cells and recruit adaptive immune effectors to generate responses that are specific and durable. Nkarta is combining its NK-cell expansion platform technology with proprietary cell engineering technologies to generate an abundant supply of NK cells, engineer enhanced NK-cell recognition of therapeutic targets, and improve persistence for sustained activity in the body. Nkarta’s goal is to develop off-the-shelf NK-cell therapy product candidates to improve outcomes for patients. The Company’s operations are based in South San Francisco, California, and it operates in one segment.

Liquidity and Management Plans

The accompanying unaudited condensed financial statements have been prepared assuming that the Company will continue as a going concern. Since inception, the Company has devoted substantially all of its efforts to organizing and staffing, business planning, raising capital, conducting preclinical studies and initiating clinical studies, and has not realized substantial revenues from its planned principal operations. In addition, the Company has a limited operating history, has incurred operating losses since inception and expects that it will continue to incur net losses into the foreseeable future as it continues its research and development activities. As of March 31, 2024, the Company had an accumulated deficit of $465.0 million and cash, cash equivalents, restricted cash and investments of $450.0 million.

Management plans to continue to incur substantial costs in order to conduct research and development activities for which additional capital will be needed. The Company intends to raise such capital through debt or equity financings or other arrangements to fund operations. Management believes that the Company’s current cash, cash equivalents, restricted cash and investments will provide sufficient funds to enable the Company to meet its obligations for at least twelve months from the filing date of this report.

On March 17, 2023, the Company filed a Registration Statement on Form S-3, as amended by the Form S-3/A filed on April 24, 2023 (the "Shelf Registration Statement"), covering the offer and sale from time to time, pursuant to Rule 415 of the Securities Act of 1933, as amended (the "Securities Act"), of up to $350.0 million in aggregate offering price of shares of the Company’s common stock, shares of the Company’s preferred stock, debt securities, warrants, rights and/or units, including up to $120.0 million in aggregate offering price of shares of the Company’s common stock, shares of the Company’s preferred stock, debt securities, warrants, rights and/or units registered on the Company’s Registration Statement on Form S-3 declared effective by the Securities and Exchange Commission (the "SEC") on September 2, 2021 (the "Prior Registration Statement") that have not yet been sold. The Shelf Registration Statement was declared effective by the SEC on May 5, 2023.

On August 12, 2021, the Company entered into a sales agreement with Cowen and Company, LLC, a sales agent, to provide for the offering, issuance and sale of up to an aggregate of $150.0 million of the Company’s common stock through an “at-the-market” equity offering program (the "ATM Offering Program") pursuant to the Prior Registration Statement and subject to the limitations thereof. For the three months ended March 31, 2024, no sales of the Company’s common stock were made pursuant to the ATM Offering Program.

On March 27, 2024, the Company completed an underwritten public offering utilizing the Shelf Registration Statement, pursuant to which it sold an aggregate of (i) 21,010,000 shares of its common stock at a price of $10.00 per share, and (ii) pre-funded warrants to purchase 3,000,031 shares of common stock at a price of $9.9999 per pre-funded warrant. The pre-funded warrants can be exercised at any time after issuance for an exercise price of $0.0001 per share, subject to certain ownership limitations. The Company raised $240.1 million in gross proceeds before underwriting discounts, commissions and other expenses of $15.0 million. See Note 9 for additional detail.

CRISPR Collaboration Agreement

3 Months Ended

Mar. 31, 2024

Collaboration Agreement [Abstract]

CRISPR Collaboration Agreement

8. CRISPR Collaboration Agreement

On May 5, 2021, the Company entered into a research collaboration agreement (as amended, the "CRISPR Agreement") with CRISPR Therapeutics AG ("CRISPR") to co-develop and co-commercialize an allogeneic, off-the-shelf chimeric antigen receptor-natural killer ("CAR NK") product candidate targeting the CD70 tumor antigen ("NKX070") and an allogeneic, off-the-shelf product candidate that comprises both engineered NK cells and engineered T cells ("NK+T"). In May 2022, the CRISPR Agreement was amended to revise the transfer of materials and nomination provisions. On March 8, 2023, the CRISPR Agreement was further amended to permit Nkarta's advancement of CRISPR-licensed product candidates targeting a specified tumor antigen (the "Specified TA") and incorporate associated development and regulatory approval milestones and sales based royalties. In addition, the Company has received licenses from CRISPR for four CRISPR-Cas9 gene editing targets and will receive a license from CRISPR for up to one more CRISPR-Cas9 gene editing target that can be engineered into an unlimited number of its own NK-cell products. CRISPR also has an option to co-develop and co-commercialize a future CAR NK program.

Under the terms of the CRISPR Agreement, the Company and CRISPR share equally in all research and development costs and potential profits worldwide related to the NKX070 product candidate, NK+T product candidate, and the potential future CAR NK program. For the NK+T program, CRISPR is responsible for gene-editing activities and T-cell related activities, and Nkarta is responsible for NK-cell related activities. The impact of the cost sharing associated with the research and development activities is included in research and development expense on the condensed statements of operations and comprehensive loss. Expenses related to services performed by the Company are classified as research and development expense. Payments received from CRISPR for partial reimbursement of expenses are recorded as a reduction of research and development expense. Reduction of research and development expense resulting from partial reimbursement from CRISPR was $0.1 million and $0.9 million for the three months ended March 31, 2024, and 2023, respectively. As of March 31, 2024, the Company had a $0.1 million receivable under the research cost sharing provision, which is included as part of prepaid expenses and other current assets in the condensed balance sheet.

For each non-collaboration product candidate incorporating a genome editing target licensed from CRISPR (a "CRISPR-Licensed Product Candidate"), other than those targeting the Specified TA, the Company would retain worldwide rights and may be required to make potential future payments based on the achievement of development and regulatory approval milestones totaling less than mid-twenty million dollars, as well as tiered royalties up to the mid-single digits on net product sales of such product candidate. For each CRISPR-Licensed Product Candidate targeting the Specified TA, the Company would retain worldwide rights and may be required to make potential future payments based on the achievement of development and regulatory approval milestones totaling less than high-forty million dollars, as well as tiered royalties up to the mid-single digits on net product sales of such product candidate. As of March 31, 2024, the Company has not paid any amounts nor are any amounts owed by the Company under the CRISPR Agreement, and no milestones have been achieved.

Leases (Tables)

3 Months Ended

Mar. 31, 2024

Leases [Abstract]

Schedule of Maturities of Operating Lease Liabilities

Maturities of operating lease liabilities under existing operating leases as of March 31, 2024 were as follows (in thousands):


Year ending December 31,	Amount
2024 (remaining nine months)	$	9,545
2025		13,027
2026		13,462
2027		13,912
2028		14,378
2029 and thereafter		72,876
Total undiscounted future minimum lease payments		137,200
Less imputed interest		(50,026	)
Total operating lease liabilities	$	87,174
Operating lease liabilities:
Current		6,078
Non-current		81,096
Total lease liability	$	87,174

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

4. Fair Value of Financial Instruments

The following tables summarize the fair value of the Company’s financial instruments (in thousands):


			Fair Value Measurements Using
	March 31, 2024		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	249,867	$	249,867	$	—	$	—
Short-term investments:
Corporate debt securities	$	38,843	$	—	$	38,843	$	—
Commercial paper		28,676		—		28,676		—
U.S. Government securities		119,590		—		119,590		—
Total short-term investments		187,109		—		187,109		—
Long-term investments:
Corporate debt securities		9,814		—		9,814	$	—
Total long-term investments		9,814		—		9,814		—
Total	$	446,790	$	249,867	$	196,923	$	—


			Fair Value Measurements Using
	December 31, 2023		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	30,751	$	30,751	$	—	$	—
Short-term investments:
Corporate debt securities	$	40,609	$	—	$	40,609	$	—
Commercial paper		38,197		—		38,197		—
Government securities		138,343		—		138,343		—
Total short-term investments		217,149		—		217,149		—
Total	$	247,900	$	30,751	$	217,149	$	—

Cash Equivalents and Investments

Financial assets measured at fair value on a recurring basis consist of the Company’s cash equivalents and investments. Cash equivalents consisted of money market funds and investments consisted of commercial paper, government securities and corporate bonds. The Company obtains pricing information from its investment manager and generally determines the fair value of investment securities using standard observable inputs, including reported trades, broker/dealer quotes, and bids and/or offers.

Investments are classified as Level 1 within the fair value hierarchy if their quoted prices are available in active markets for identical securities. Investments in money market funds of $249.9 million and $30.8 million as of March 31, 2024 and December 31, 2023, respectively, were classified as Level 1 instruments and were included in cash and cash equivalents.

Investments in corporate debt securities, commercial paper and Government securities included in short-term and long-term investments are valued using Level 2 inputs. Level 2 securities are initially valued at the transaction price and subsequently valued and reported upon utilizing inputs other than quoted prices that are observable either directly or indirectly, such as quotes from third-party pricing vendors. Fair values determined by Level 2 inputs, which utilize data points that are observable such as quoted prices, interest rates and yield curves, require the exercise of judgment and use of estimates, that if changed, could significantly affect the Company’s financial position and results of operations. The marketable securities of $196.9 million and $217.1 million as of March 31, 2024 and December 31, 2023, respectively, were classified as Level 2 instruments. As of March 31, 2024, marketable securities of $187.1 million were included in short-term investments, and marketable securities of $9.8 million were included in long-term investments.

Accrued interest receivable related to investments was $1.2 million as of March 31, 2024 and December 31, 2023, and included as part of prepaid expenses and other current assets in the condensed balance sheets.

The following tables summarize the Company’s short-term and long-term investments as of March 31, 2024 and December 31, 2023 (in thousands):


		March 31, 2024
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	38,863	$	(25	)	$	5	$	38,843
Commercial paper	1 year or less		28,684		(8	)		—		28,676
U.S. Government securities	1 year or less		119,668		(82	)		4		119,590
Corporate debt securities	Greater than 1 year		9,835		(21	)		—		9,814
Total		$	197,050	$	(136	)	$	9	$	196,923


		December 31, 2023
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	40,602	$	(11	)	$	18	$	40,609
Commercial paper	1 year or less		38,198		(2	)		1		38,197
Government securities	1 year or less		138,341		(56	)		58		138,343
Total		$	217,141	$	(69	)	$	77	$	217,149

The Company has classified its investment securities as current and non-current assets on the condensed balance sheets based on each security's contractual maturity date, and all investment securities are accounted for as available-for-sale because these investment securities are considered available for use in current operations.

The Company considers whether unrealized losses have resulted from a credit loss or other factors. The unrealized losses on the Company’s available-for-sale securities as of March 31, 2024 and December 31, 2023 were caused by fluctuations in market value and interest rates as a result of the economic environment and not credit risk. The Company concluded that an allowance for credit losses was unnecessary as of March 31, 2024 and December 31, 2023. It is neither management’s intention to sell nor is it more likely than not that the Company will be required to sell these investments prior to recovery of their cost basis or recovery of fair value. Unrealized gains and losses are included in accumulated other comprehensive loss.

There was no realized gain or loss on available-for-sale securities for the three months ended March 31, 2024. During the three months ended March 31, 2023, there were immaterial realized gains recognized on available-for-sale securities sold in the period. The Company uses the specific identification method to determine the cost basis of investments sold.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Mar. 27, 2024	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value of stock option		$ 4.98	$ 4.22
Intrinsic value of options exercised		$ 700	$ 700
Unrecognized compensation cost		$ 25,100
Unrecognized compensation cost, expected to be recognized over weighted average remaining service period		3 years
Common stock shares issued and sold	21,010,000
Common stock price	$ 10
Gross proceeds from offering	$ 240,100
Stock issuance discounts and commission	$ 15,000	$ 15,027
Pre-funded warrant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants	$ 0.0001
Common stock price	$ 9.9999
Pre-funded warrants to purchase shares of common stock	3,000,031
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value per share, granted		$ 6.01	$ 5.57
Unrecognized compensation cost		$ 7,600
Unrecognized compensation cost, expected to be recognized over weighted average remaining service period		3 years 3 months 18 days
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in share limit as percentage of outstanding shares of common stock on last trading day in prior year		1.00%
Number of common stock available for issuance		1,000,000
Maximum percentage of employee compensation eligible for plan		15.00%
Offering period		6 months
Commons stock purchase price as percentage of fair value		85.00%
Shares issued		1,706,798
2020 Employee Stock Purchase Plan \| Accrued and Other Current Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee contributions to ESPP		$ 300
Sale of Common Stock and Pre-funded Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued and sold	21,010,000
Common stock price	$ 10
Gross proceeds from offering	$ 240,100
Stock issuance discounts and commission	14,400
Other offering expenses	$ 600
Sale of Common Stock and Pre-funded Warrants \| Pre-funded warrant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants	$ 0.0001
Common stock price	$ 9.9999
Pre-funded warrants to purchase shares of common stock	3,000,031
2020 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance		10,847,981
Increase in share limit as percentage of outstanding shares of common stock on last trading day in prior year		5.00%
Number of common stock available for issuance		2,674,638

Fair Value of Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Realized gain or loss on available-for-sale securities	$ 0	$ 34,000
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments	249,900,000		$ 30,800,000
Significant Other Observable Inputs (Level 2)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Marketable securities	196,900,000		217,100,000
Accrued interest receivable	1,200,000		$ 1,200,000
Significant Other Observable Inputs (Level 2) \| Short-term investments
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Marketable securities	187,100,000
Significant Other Observable Inputs (Level 2) \| Long Term Investments
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Marketable securities	$ 9,800,000

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Summary of Stock Option Activity

The following table summarizes the option activity under the 2020 Plan and 2015 Plan during the three months ended March 31, 2024:


	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2023		6,716,526		$	12.99		7.5		8,279
Granted		1,955,300			6.11
Exercised		(128,671	)		4.49
Forfeited		(281,206	)		22.22
Outstanding at March 31, 2024		8,261,949		$	11.18		8.1		30,907
Exercisable at March 31, 2024		3,591,101		$	15.68		6.8		9,692
Vested and expected to vest at March 31, 2024		8,261,949		$	11.18		8.1		30,907

Summary of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity under the 2020 Plan during the three months ended March 31, 2024:


	Number of shares			Weighted average grant date fair value per share		Weighted average remaining contractual term (in years)
Outstanding at December 31, 2023		594,768		$	8.16		1.4
Granted		775,153			6.01
Vested		(133,595	)		7.45
Forfeited		(19,509	)		7.22
Outstanding at March 31, 2024		1,216,817		$	6.88		2.0

Summary of Share-based Compensation Expense

Share-based compensation expense for the three months ended March 31, 2024 and 2023 was as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development	$	2,200	$	2,082
General and administrative		2,168		2,664
Total share-based compensation	$	4,368	$	4,746

Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2024

Summary of Fair Value of Financial Instrument

The following tables summarize the fair value of the Company’s financial instruments (in thousands):


			Fair Value Measurements Using
	March 31, 2024		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	249,867	$	249,867	$	—	$	—
Short-term investments:
Corporate debt securities	$	38,843	$	—	$	38,843	$	—
Commercial paper		28,676		—		28,676		—
U.S. Government securities		119,590		—		119,590		—
Total short-term investments		187,109		—		187,109		—
Long-term investments:
Corporate debt securities		9,814		—		9,814	$	—
Total long-term investments		9,814		—		9,814		—
Total	$	446,790	$	249,867	$	196,923	$	—


			Fair Value Measurements Using
	December 31, 2023		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	30,751	$	30,751	$	—	$	—
Short-term investments:
Corporate debt securities	$	40,609	$	—	$	40,609	$	—
Commercial paper		38,197		—		38,197		—
Government securities		138,343		—		138,343		—
Total short-term investments		217,149		—		217,149		—
Total	$	247,900	$	30,751	$	217,149	$	—

Schedule of Short-term Investments

The following tables summarize the Company’s short-term and long-term investments as of March 31, 2024 and December 31, 2023 (in thousands):


		March 31, 2024
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	38,863	$	(25	)	$	5	$	38,843
Commercial paper	1 year or less		28,684		(8	)		—		28,676
U.S. Government securities	1 year or less		119,668		(82	)		4		119,590
Corporate debt securities	Greater than 1 year		9,835		(21	)		—		9,814
Total		$	197,050	$	(136	)	$	9	$	196,923


		December 31, 2023
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	40,602	$	(11	)	$	18	$	40,609
Commercial paper	1 year or less		38,198		(2	)		1		38,197
Government securities	1 year or less		138,341		(56	)		58		138,343
Total		$	217,141	$	(69	)	$	77	$	217,149

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Balance Sheet Components

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Property and Equipment, Net

Property and equipment, net is comprised of the following (in thousands):


	March 31, 2024			December 31, 2023
Leasehold improvements	$	66,618		$	66,618
Furniture and fixtures		746			745
Research equipment		15,430			14,298
Computers and software		404			404
Construction in progress		9,273			8,954
Total property and equipment, gross		92,471			91,019
Less accumulated depreciation and amortization		(13,949	)		(11,693	)
Total property and equipment, net	$	78,522		$	79,326

Depreciation and amortization expense was $2.3 million and $0.8 million for the three months ended March 31, 2024, and 2023, respectively.

Accrued and Other Current Liabilities

Accrued other current liabilities are comprised of the following (in thousands):


	March 31, 2024		December 31, 2023
Accrued compensation	$	3,774	$	6,722
Accrued research and development costs		7,452		5,845
Accrued property and equipment		91		174
Accrued stock issuance costs		615		—
Other accrued and current liabilities		1,002		855
Total accrued and other liabilities	$	12,934	$	13,596

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Balance Sheet Components - Schedule of Accrued Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued compensation	$ 3,774	$ 6,722
Accrued research and development costs	7,452	5,845
Accrued property and equipment	91	174
Accrued stock issuance costs	615
Other accrued and current liabilities	1,002	855
Total accrued and other liabilities	$ 12,934	$ 13,596

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On March 28, 2024, Paul Hastings, Chief Executive Officer, adopted a trading arrangement for the sale of shares of our common stock (a "Rule 10b5-1 Trading Plan") that is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c). Mr. Hastings’ Rule 10b5-1 Trading Plan provides for the sale of up to 439,061 shares of common stock (including shares obtained from the exercise of vested stock options and the associated sale of such shares) pursuant to the terms of the plan. The first possible trade date under Mr. Hastings’ Rule 10b5-1 Trading Plan is June 27, 2024, and the plan is effective through June 27, 2025 unless earlier terminated in accordance with the terms of the plan. On March 15, 2024, Mr. Hastings terminated his prior Rule 10b5-1 Trading Plan originally adopted on June 27, 2022, for the sale of up to 340,000 shares of common stock, subject to certain conditions, until July 31, 2024, of which 160,000 shares remained unsold at the date his prior Rule 10b5-1 Trading Plan was terminated. On March 28, 2024, Alyssa Levin, Chief Financial and Business Officer, adopted a Rule 10b5-1 Trading Plan that is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c). Ms. Levin’s Rule 10b5-1 Trading Plan provides for the sale of up to 110,600 shares of common stock (including shares obtained from the exercise of vested stock options and the associated sale of such shares), as well as 100% of the net shares of common stock resulting from the vesting of previously-awarded restricted stock units covering 28,000 shares of common stock, in each case pursuant to the terms of the plan. The first possible trade date under Ms. Levin’s Rule 10b5-1 Trading Plan is July 1, 2024, and the plan is effective through June 26, 2026 unless earlier terminated in accordance with the terms of the plan. On March 28, 2024, Alicia Hager, Chief Legal Officer, adopted a Rule 10b5-1 Trading Plan that is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c). Dr. Hager’s Rule 10b5-1 Trading Plan provides for the sale of up to 216,025 shares of common stock (including shares obtained from the exercise of vested stock options and the associated sale of such shares), ,as well as 100% of the net shares of common stock resulting from the vesting of previously-awarded restricted stock units covering 30,575 shares of common stock, in each case pursuant to the terms of the plan. The first possible trade date under Dr. Hager’s Rule 10b5-1 Trading Plan is June 27, 2024, and the plan is effective through November 13, 2025 unless earlier terminated in accordance with the terms of the plan. On March 28, 2024, Ralph Brandenberger, Chief Technical Officer, adopted a Rule 10b5-1 Trading Plan that is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c). Dr. Brandenberger’s Rule 10b5-1 Trading Plan provides for the sale of up to 36,062 shares of common stock (including shares obtained from the exercise of vested stock options and the associated sale of such shares), subject to certain conditions, as well as 100% of the net shares of common stock resulting from the vesting of previously-awarded restricted stock units covering 43,025 shares of common stock, in each case pursuant to the terms of the plan. The first possible trade date under Dr. Brandenberger’s Rule 10b5-1 Trading Plan is July 1, 2024, and the plan is effective through June 26, 2026 unless earlier terminated in accordance with the terms of the plan. On March 28, 2024, Leone Patterson, director and chairperson of the audit committee of the Company's Board of Directors, adopted a Rule 10b5-1 Trading Plan that is intended to satisfy the affirmative defense conditions of Exchange Act Rule 10b5-1(c). Ms. Patterson’s Rule 10b5-1 Trading Plan provides for the sale of up to 39,729 shares of common stock (including shares obtained from the exercise of vested stock options and the associated sale of such shares) pursuant to the terms of the plan. The first possible trade date under Ms. Patterson’s Rule 10b5-1 Trading Plan is June 27, 2024, and the plan is effective through June 19, 2026 unless earlier terminated in accordance with the terms of the plan.
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false
Paul Hastings
Trading Arrangements, by Individual
Name	Paul Hastings
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 28, 2024
Rule 10b5-1 Arrangement Terminated	true
Termination Date	March 15, 2024
Aggregate Available	439,061
Paul Hastings
Trading Arrangements, by Individual
Aggregate Available	340,000
Alyssa Levin
Trading Arrangements, by Individual
Name	Alyssa Levin
Title	Chief Financial and Business Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 28, 2024
Rule 10b5-1 Arrangement Terminated	true
Termination Date	June 26, 2026
Aggregate Available	110,600
Alicia Hager
Trading Arrangements, by Individual
Name	Alicia Hager
Title	Chief Legal Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 28, 2024
Rule 10b5-1 Arrangement Terminated	true
Termination Date	November 13, 2025
Aggregate Available	216,025
Ralph Brandenberger
Trading Arrangements, by Individual
Name	Ralph Brandenberger
Title	Chief Technical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 28, 2024
Rule 10b5-1 Arrangement Terminated	true
Termination Date	June 26, 2026
Aggregate Available	36,062
Leone Patterson
Trading Arrangements, by Individual
Name	Leone Patterson
Title	director and chairperson
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 28, 2024
Rule 10b5-1 Arrangement Terminated	true
Termination Date	June 19, 2026
Aggregate Available	39,729

Net Loss Per Share

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

3. Net Loss Per Share

The following tables summarize the computation of the basic and diluted net loss per share (in thousands except share and per share data):


	Three Months Ended March 31,
	2024			2023
Numerator:
Net loss	$	(29,518	)	$	(30,815	)
Denominator:
Weighted average common shares outstanding		50,517,632			48,921,535
Less: weighted average unvested common stock issued upon early exercise of common stock options		—			(209	)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants		164,837			—
Weighted average shares used to compute net loss per share, basic and diluted		50,682,469			48,921,326
Net loss per share, basic and diluted	$	(0.58	)	$	(0.63	)

The following table summarizes the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be antidilutive:


	As of March 31,
	2024		2023
Common stock options		8,261,949		6,820,096
Restricted stock units		1,216,817		799,930
Unvested common stock upon early exercise of common stock options		—		113
		9,478,766		7,620,139

CONDENSED STATEMENT OF CASH FLOWS (Unaudited) - USD ($)	3 Months Ended
CONDENSED STATEMENT OF CASH FLOWS (Unaudited) - USD ($)	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net loss	$ (29,518,000)	$ (30,815,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	4,368,000	4,746,000
Depreciation and amortization	2,255,000	797,000
Accretion and amortization of premiums and discounts on investments, net	(1,568,000)	(2,253,000)
Realized gain on investments	0	(34,000)
Non-cash lease expense	592,000	545,000
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(428,000)	(406,000)
Operating lease liabilities	(1,164,000)	7,992,000
Accounts payable and accrued and other liabilities	(3,043,000)	(1,330,000)
Net cash used in operating activities	(28,506,000)	(20,758,000)
Cash flows from investing activities
Purchases of property and equipment	(175,000)	(4,823,000)
Purchases of investments	(40,040,000)	(84,288,000)
Maturities of investments	61,700,000	126,040,000
Net cash provided by investing activities	21,485,000	36,929,000
Cash flows from financing activities
Proceeds from stock option exercises	578,000	1,000
Proceeds from issuance of common stock and pre-funded warrants, net of underwriting fees	225,688,000
Net cash provided by financing activities	226,266,000	1,000
Net increase in cash and cash equivalents	219,245,000	16,172,000
Cash, cash equivalents, and restricted cash beginning of period	33,783,000	40,237,000
Cash, cash equivalents, and restricted cash end of period	253,028,000	56,409,000
Reconciliation of cash, cash equivalents and restricted cash to the balance sheet:
Cash and cash equivalents	250,285,000	53,666,000
Restricted cash	2,743,000	2,743,000
Total cash, cash equivalents and restricted cash	253,028,000	56,409,000
Supplemental disclosures of non-cash investing activities:
Stock issuance costs included in accrued and other current liabilities	615,000
Acquisitions of property and equipment in accounts payable and accrued and other current liabilities	$ 1,277,000	$ 3,761,000

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss	$ (29,518)	$ (30,815)
Denominator:
Weighted average common shares outstanding	50,517,632	48,921,535
Less: weighted average unvested common stock issued upon early exercise of common stock options		(209)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants	164,837
Weighted average shares used to compute net loss per share, basic	50,682,469	48,921,326
Weighted average shares used to compute net loss per share, diluted	50,682,469	48,921,326
Net loss per share, basic	$ (0.58)	$ (0.63)
Net loss per share, diluted	$ (0.58)	$ (0.63)

Net Loss Per Share - Summarizes the Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	9,478,766	7,620,139
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	8,261,949	6,820,096
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,216,817	799,930
Unvested Common Stock Upon Early Exercise of Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		113

Commitments and Contingencies - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Liabilities recorded for agreements	$ 0	$ 0
Contingency loss	0
Provision for contingency loss	0
Agreement with Financial Institution
Loss Contingencies [Line Items]
Letters of credit outstanding amount	$ 2,700,000
Agreement with Financial Institution \| Minimum
Loss Contingencies [Line Items]
Letter of credit notice period by financial institution before annual expiration date	30 days
Agreement with Financial Institution \| Maximum
Loss Contingencies [Line Items]
Letter of credit notice period by financial institution before annual expiration date	60 days

Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, outstanding beginning balance	6,716,526
Number of shares, granted	1,955,300
Number of shares, exercised	(128,671)
Number of shares, forfeited	(281,206)
Number of shares, outstanding ending balance	8,261,949	6,716,526
Number of shares, exercisable	3,591,101
Number of shares, vested and expected to vest	8,261,949
Weighted-average exercise price, outstanding beginning balance	$ 12.99
Weighted-average exercise price, granted	6.11
Weighted-average exercise price, exercised	4.49
Weighted-average exercise price, forfeited	22.22
Weighted-average exercise price, outstanding ending balance	11.18	$ 12.99
Weighted-average exercise price, exercisable	15.68
Weighted-average exercise price, vested and expected to vest	$ 11.18
Weighted-average remaining contractual term (in years), outstanding balance	8 years 1 month 6 days	7 years 6 months
Weighted-average remaining contractual term (in years), exercisable	6 years 9 months 18 days
Weighted-average remaining contractual term (in years), vested and expected to vest	8 years 1 month 6 days
Aggregate intrinsic value, outstanding balance	$ 30,907	$ 8,279
Aggregate intrinsic value, exercisable	9,692
Aggregate intrinsic value, vested and expected to vest	$ 30,907

Statement - CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands		3 Months Ended
	Mar. 27, 2024	Mar. 31, 2024
Statement of Stockholders' Equity [Abstract]
Issuance costs	$ 15,000	$ 15,027

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 92,471	$ 91,019
Less accumulated depreciation and amortization	(13,949)	(11,693)
Total property and equipment, net	78,522	79,326
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	66,618	66,618
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, gross	746	745
Research Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	15,430	14,298
Computers and Software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	404	404
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 9,273	$ 8,954

Stockholders' Equity

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Stockholders' Equity

9. Stockholders' Equity

Equity Incentive Plan

The Company’s 2020 Performance Incentive Plan (the "2020 Plan"), which was adopted by the Company’s board of directors in June 2020 and approved by the Company’s stockholders in July 2020, became effective upon the consummation of the Company’s initial public offering in July 2020 ("IPO"). Upon the effectiveness of the 2020 Plan, no further grants may be made under the Company’s 2015 Equity Incentive Plan (the "2015 Plan"). The 2020 Plan allows for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, stock bonuses, restricted stock, stock units and other forms of awards including cash awards to its officers, directors, employees, consultants and advisors.

As of March 31, 2024, a total of 10,847,981 shares of the Company’s common stock were authorized for issuance with respect to awards granted under the 2020 Plan (this number of shares gives effect to the annual increases in the 2020 Plan share limit, as described in the next sentence, through that date). The share limit will automatically increase on the first trading day in January of each year by an amount equal to the lesser of (1) 5% of the total number of outstanding shares of the Company’s common stock on the last trading day in December in the prior year, or (2) such lesser number as determined by the Company’s board of directors. Any shares subject to awards granted under the 2020 Plan or the 2015 Plan that are not paid, delivered or exercised before they expire or are canceled or terminated, or otherwise fail to vest, as well as shares used to pay the purchase or exercise price of such awards or

related tax withholding obligations, will become available for new award grants under the 2020 Plan. A total of 2,674,638 shares were available for issuance under the 2020 Plan as of March 31, 2024.

The following table summarizes the option activity under the 2020 Plan and 2015 Plan during the three months ended March 31, 2024:


	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2023		6,716,526		$	12.99		7.5		8,279
Granted		1,955,300			6.11
Exercised		(128,671	)		4.49
Forfeited		(281,206	)		22.22
Outstanding at March 31, 2024		8,261,949		$	11.18		8.1		30,907
Exercisable at March 31, 2024		3,591,101		$	15.68		6.8		9,692
Vested and expected to vest at March 31, 2024		8,261,949		$	11.18		8.1		30,907

The weighted average grant date fair value of stock option grants was $4.98 and $4.22 per share for the three months ended March 31, 2024 and 2023, respectively. The intrinsic value of options exercised was $0.7 million and immaterial for the three months ended March 31, 2024 and 2023, respectively.

The following table summarizes the restricted stock unit activity under the 2020 Plan during the three months ended March 31, 2024:


	Number of shares			Weighted average grant date fair value per share		Weighted average remaining contractual term (in years)
Outstanding at December 31, 2023		594,768		$	8.16		1.4
Granted		775,153			6.01
Vested		(133,595	)		7.45
Forfeited		(19,509	)		7.22
Outstanding at March 31, 2024		1,216,817		$	6.88		2.0

The weighted average grant date fair value of restricted stock units was $6.01 and $5.57 per share for the three months ended March 31, 2024 and 2023, respectively. There were no restricted stock units that vested for the three months ended March 31, 2024 and 2023.

Employee Stock Purchase Plan

The Company’s 2020 Employee Stock Purchase Plan (the "ESPP"), which was adopted by the Company’s board of directors in June 2020 and approved by the Company’s stockholders in July 2020, became effective upon the consummation of the IPO. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for six-month offering periods, and at the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. The six-month offering periods extend from June to November and December to May. As of March 31, 2024, 1,706,798 shares of the Company’s common stock remained available for issuance under the ESPP (after giving effect to share purchases under the ESPP, and annual increases in the ESPP share limit as described in the next sentence through that date). The number of shares of the Company’s common stock available for issuance under the ESPP automatically increases on the first trading day in January of each year by an amount equal to the lesser of (i) 1% of the total number of outstanding shares of the Company’s common stock issued and outstanding on December 31 of the immediately preceding calendar year, (ii) 1,000,000 shares, or (iii) such lesser number as determined by the Company’s board of directors. As of March 31, 2024, employee contributions to the ESPP were $0.3 million and included as part of accrued and other current liabilities in the condensed balance sheets.

Share-Based Compensation Expense

Share-based compensation expense for the three months ended March 31, 2024 and 2023 was as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development	$	2,200	$	2,082
General and administrative		2,168		2,664
Total share-based compensation	$	4,368	$	4,746

The total unrecognized compensation cost related to unvested stock options was $25.1 million, which is expected to be recognized over a weighted average remaining service period of 3.0 years as of March 31, 2024.

The total unrecognized compensation cost related to unvested restricted stock units was $7.6 million, which is expected to be recognized over a weighted average remaining service period of 3.3 years as of March 31, 2024.

Sale of Common Stock and Pre-funded Warrants

On March 27, 2024, the Company completed an underwritten public offering utilizing the Shelf Registration Statement, pursuant to which it sold an aggregate of (i) 21,010,000 shares of its common stock at a price of $10.00 per share, and (ii) pre-funded warrants to purchase 3,000,031 shares of its common stock at a price of $9.9999 per pre-funded warrant. The pre-funded warrants can be exercised at any time after issuance for an exercise price of $0.0001 per share, subject to certain ownership limitations. As of March 31, 2024, none of the pre-funded warrants have been exercised. The Company raised $240.1 million in gross proceeds before underwriting discounts and commissions of $14.4 million and estimated other offering expenses of $0.6 million.

In accordance with ASC 480-10, Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity ("ASC 480"), and ASC 815-40 ("ASC 815"), Accounting for Derivative Financial Instruments Indexed to, and Potentially Settled in, a Company’s Own Stock, the Company determined that the pre-funded warrants should be equity classified because they are freestanding financial instruments, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, permit the holders to receive a fixed number of shares of common stock upon exercise, are indexed to the Company’s common stock and meet the equity classification criteria.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Paragraph 13
-Subparagraph (h)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
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-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-Paragraph 6
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-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
-Paragraph 14
-Subparagraph (c)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Basis of Presentation and Significant Accounting Policies

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

2. Basis of Presentation and Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed financial statements as of March 31, 2024 and for the three months ended March 31, 2024 and 2023 have been prepared in accordance with U.S. generally accepted accounting principle ("U.S. GAAP") for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act, as amended. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows for the periods presented.

The results for the three months ended March 31, 2024 are not necessarily indicative of the results expected for the full year or any subsequent interim period. The condensed balance sheet as of December 31, 2023 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2023, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed by the Company with the SEC on March 21, 2024.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to preclinical studies and clinical trial accruals, fair value of assets and liabilities, impairment of assets, leases, share-based compensation and income taxes. Management bases its estimates on historical experience, knowledge of current events and actions it may undertake in the future that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares and pre-funded warrants outstanding for the period, without consideration of potential dilutive securities. Pre-funded warrants are considered outstanding for the purposes of computing basic and diluted net loss per share because shares may be issued for little or no additional consideration and are fully vested and exercisable after the original issuance date of the pre-funded warrants. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares and pre-funded warrants plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include unvested common stock, outstanding stock options and restricted stock units under the Company’s equity incentive plans, have been excluded from the computation of diluted net loss per share as they would be antidilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

Long-Lived Asset Impairment

The Company assesses the impairment of long-lived assets whenever events or changes in business circumstances indicate that the carrying amounts of the asset or group of assets may not be fully recoverable. In the case of property and equipment and right-of-use assets for the Company's leases, the Company determines whether there has been an impairment by comparing the carrying value of the group of assets to the anticipated undiscounted net future cash flows associated with the group of assets. If such cash flows are less than the carrying value, the Company writes down the group of assets to its fair value, which may be measured as anticipated net cash flows associated with the group of assets, discounted at a rate that the Company believes a market participant would utilize to reflect the risks associated with the cash flows, such as credit risk. See Note 6 for additional information regarding the prior year impairment charge the Company recorded in connection with its leased facilities.

Recent Accounting Pronouncements

In November 2023, the Financial Accounting Standard Board ("FASB") issued Accounting Standards Update ("ASU") No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires disclosure of incremental segment information on an interim and annual basis. This ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal periods beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. The Company is currently evaluating the impact of the guidance on the financial statements and disclosures.

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures ("ASU 2023-09"). ASU 2023-09 is intended to enhance the transparency and decision usefulness of income tax disclosures. The amendments in ASU 2023-09 address investor requests for enhanced income tax information primarily through changes to the rate reconciliation and income taxes paid information. ASU 2023-09 will be effective for us in the annual period beginning January 1, 2025, though early adoption is permitted. The Company is currently evaluating the presentational effect that ASU 2023-09 will have on its financial statements.

In August 2020, the FASB issued ASU No. 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 740-20) and Derivative and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”), which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. ASU 2020-06 also removes certain settlement conditions that are required for equity-linked contracts to qualify for the derivative scope exception, and it simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for the Company beginning on January 1, 2024. The adoption of ASU 2020-06 does not have a material impact on the financial position, results of operations or cash flows of the Company.

There were no other significant updates to the recently issued accounting standards other than as disclosed herewith. Although there are several other new accounting pronouncements issued or proposed by the FASB, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Organization and Description of Business - Additional Information (Details) $ / shares in Units, $ in Thousands					3 Months Ended
	Mar. 27, 2024 USD ($) $ / shares shares	Mar. 17, 2023 USD ($)	Sep. 02, 2021 USD ($)	Aug. 12, 2021 USD ($)	Mar. 31, 2024 USD ($) Segment shares	Dec. 31, 2023 USD ($)
Class Of Stock [Line Items]
Number of operating segments \| Segment					1
Accumulated deficit					$ 464,952	$ 435,434
Cash, cash equivalents restricted cash and short-term investments					450,000
Common stock shares issued and sold \| shares	21,010,000
Common stock price \| $ / shares	$ 10
Gross proceeds from offering	$ 240,100
Stock issuance discounts, commissions and other expenses	$ 15,000				15,027
Maximum
Class Of Stock [Line Items]
Proceeds from issuance initial public offering				$ 150,000
Pre-funded warrant
Class Of Stock [Line Items]
Common stock price \| $ / shares	$ 9.9999
Pre-funded warrants to purchase shares of common stock \| shares	3,000,031
Exercise price of warrants \| $ / shares	$ 0.0001
Aggregate offering price					$ 225,073
IPO \| Maximum
Class Of Stock [Line Items]
Aggregate offering price		$ 350,000	$ 120,000
Common Stock
Class Of Stock [Line Items]
Common stock shares issued and sold \| shares					0
Common Stock \| Pre-funded warrant
Class Of Stock [Line Items]
Common stock shares issued and sold \| shares					21,010,000
Aggregate offering price					$ 2

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 06, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-39370
Entity Registrant Name	Nkarta, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4515206
Entity Address, Address Line One	1150 Veterans Boulevard
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	925
Local Phone Number	407-1049
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	NKTX
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		70,467,620
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001787400

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Leases [Abstract]
2024 (remaining nine months)	$ 9,545
2025	13,027
2026	13,462
2027	13,912
2028	14,378
2029 and thereafter	72,876
Total undiscounted future minimum lease payments	137,200
Less imputed interest	(50,026)
Total operating lease liabilities	87,174
Operating lease liabilities:
Operating lease liabilities, current portion	6,078	$ 6,069
Operating lease liabilities, net of current portion	81,096	$ 82,270
Total lease liability	$ 87,174

CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 250,285	$ 31,040
Short-term investments	187,109	217,149
Prepaid expenses and other current assets	5,387	4,882
Total current assets	442,781	253,071
Long-term investments	9,814
Restricted cash	2,743	2,743
Property and equipment, net	78,522	79,326
Operating lease right-of-use assets	39,357	39,949
Other long-term assets	3,719	3,796
Total assets	576,936	378,885
Current liabilities
Accounts payable	3,177	3,665
Operating lease liabilities, current portion	6,078	6,069
Accrued and other current liabilities	12,934	13,596
Total current liabilities	22,189	23,330
Operating lease liabilities, net of current portion	81,096	82,270
Total liabilities	103,285	105,600
Commitments and contingencies (Note 7)
Stockholders’ equity
Common stock	7	5
Additional paid-in capital	938,723	708,706
Accumulated other comprehensive (loss) income	(127)	8
Accumulated deficit	(464,952)	(435,434)
Total stockholders’ equity	473,651	273,285
Total liabilities and stockholders’ equity	$ 576,936	$ 378,885