0000950170-25-045262 | 10-K | XBRL Viewer

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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2024	Mar. 21, 2025	Jun. 30, 2024
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 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
Security Exchange Name	NASDAQ
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		70,957,554
Document Financial Statement Error Correction [Flag]	false
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001787400
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
ICFR Auditor Attestation Flag	false
Entity Public Float			$ 270.6
Auditor Name	Ernst & Young LLP
Auditor Location	California
Auditor Firm ID	42
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s Definitive Proxy Statement for the 2024 Annual Meeting of Stockholders to be filed with the U.S. Securities and Exchange Commission pursuant to Regulation 14A within 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K are incorporated by reference in Part III, Items 10-14 of this Annual Report on Form 10-K.
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying balance sheets of Nkarta, Inc. (the Company) as of December 31, 2024 and 2023, the related statements of operations and comprehensive loss, stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles.

Net Loss Per Share

12 Months Ended

Dec. 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):


	Year Ended December 31,
	2024			2023
Numerator:
Net loss	$	(108,790	)	$	(117,501	)
Denominator:
Weighted average common shares outstanding		65,570,217			49,014,357
Less: weighted average unvested common stock issued upon early exercise of common stock options		—			(57	)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants		2,295,106			—
Weighted average shares used to compute net loss per share, basic and diluted		67,865,323			49,014,300
Net loss per share, basic and diluted	$	(1.60	)	$	(2.40	)

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 anti-dilutive:


	December 31,
	2024		2023
Common stock options		9,069,194		6,716,526
Restricted stock units		1,167,911		594,768
		10,237,105		7,311,294

Income Taxes

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

Due to the Company’s net losses for the years ended December 31, 2024 and 2023, and since the Company has a full valuation allowance against deferred tax assets, there was no tax provision or benefit for income taxes recorded in the years presented.

A reconciliation on income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows (in thousands):


	Year Ended December 31,
	2024			2023
Income tax benefit at statutory rates	$	(22,846	)	$	(24,675	)
State income tax, net of federal benefit		(1,701	)		(1,438	)
Permanent items		2,877			1,656
Research and development credits		(3,640	)		(6,170	)
Change in valuation allowance		25,310			30,627
Income tax expense	$	—		$	—

Significant components of the Company’s deferred tax assets are shown below (in thousands):


	December 31,
	2024			2023
Deferred tax assets:
Net operating loss carry forwards	$	53,520		$	43,491
Depreciation and amortization		338			334
Research and development credits		25,123			19,782
Share-based compensation		5,122			4,668
Accrued expenses		1,535			1,402
Lease liability		16,857			18,551
Other, net		62			49
Section 174 Capitalized R&D		39,385			30,147
Total deferred tax assets		141,942			118,424
Valuation allowance for deferred tax assets		(127,479	)		(102,169	)
Deferred tax assets, net of valuation allowance		14,463			16,255
Deferred tax liabilities:
ROU asset		(7,644	)		(8,404	)
Depreciation and amortization		(6,819	)		(7,851	)
Net deferred tax assets	$	—		$	—

The Company has a net operating loss and has provided a valuation allowance against net deferred tax assets due to uncertainties regarding the Company’s ability to realize these assets. The valuation allowance increased by $25.3 million and $30.6 million as of December 31, 2024 and 2023, respectively.

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. Due to the Company’s history of losses, and lack of other positive evidence, the Company has determined that it is more likely than not that its net deferred tax assets will not be realized, and therefore, the net deferred tax assets are substantially offset by a valuation allowance as of December 31, 2024 and 2023. The deferred tax assets were primarily comprised of federal and state tax net operating losses, Section 174 capitalized R&D expenses, and tax credit carryforwards.

As of December 31, 2024, the Company had net operating loss ("NOL") carryforwards of approximately $233.2 million and $65.1 million, available to reduce future taxable income, if any, for federal and California state income tax purposes, respectively. Of the $233.2 million federal NOL carryforwards, $3.2 million will begin expiring in 2035, if not utilized, while $230.0 million can be carried forward indefinitely. The state NOL carryforwards will begin expiring in 2036, if not utilized.

The Company also had federal and state research and development credit carry forwards of approximately $22.0 million and $9.5 million, respectively, as of December 31, 2024. The federal credits will begin expiring in 2035 if not utilized. The California credits have no expiration date.

Utilization of the NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by Section 382 of the Internal Revenue Code of 1986, as amended (the "Code"), as well as similar state provisions. The future utilization of the Company’s NOL and tax credit carryforwards to offset future taxable income may be subject to a substantial annual limitation as a result of changes in ownership by stockholders that hold 5% or more of the Company’s common stock. An assessment of such ownership changes under Section 382 was not completed through December 31, 2024. To the extent that an assessment is completed in the future, the Company’s ability to utilize tax attributes could be restricted on a year-by-year basis and certain attributes could expire before they are utilized. The Company will examine the impact of any potential ownership changes in the future.

The Company has not been audited by the Internal Revenue Service or any state income or franchise tax agency. As of December 31, 2024, its federal and state returns for the years ended 2015 through the current period are still open to examination. In addition, all of the net operating losses and research and development credit carryforwards that may be used in future years are still subject to inquiry given that the statute of limitation for these items would begin in the year of the utilization. The balance of gross unrecognized tax benefits as of December 31, 2024 and 2023 was approximately $4.7 million and $3.7 million, respectively, all of which would affect the Company’s income tax expense if recognized, before consideration of the Company’s valuation allowance. The Company does not expect its unrecognized tax benefits to change significantly over the next 12 months. The Company recognizes interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. There was no interest and penalties for the years ended December 31, 2024 and 2023. The Company files income tax returns in the United States federal jurisdiction and various state jurisdictions and is not currently under examination by any taxing authority for any open tax year. Due to net operating loss carryforwards, all years remain open for income tax examination. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the IRS or state tax authorities to the extent utilized in a future period. No federal or state tax audits are currently in process.

The following table summarizes the changes in the Company’s gross unrecognized tax benefits (in thousands):


	December 31,
	2024			2023
Balance at the beginning of the year	$	3,738		$	2,339
Increases (decreases) related to tax positions taken in prior years		(83	)		102
Increases related to tax positions taken in current year		1,093			1,297
Balance at the end of the year	$	4,748		$	3,738

- Definition

The entire disclosure for income tax.

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+ Details

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 9.2	$ 5.9

Stockholders' Equity

12 Months Ended

Dec. 31, 2024

Equity [Abstract]

Stockholders' Equity

10. Stockholders’ Equity

Common Stock

On June 13, 2024, the stockholders approved an amendment to the Company's Restated Certificate of Incorporation to increase the number of total authorized shares of the Company's common stock, $0.0001 par value per share, from 100,000,000 to 200,000,000 shares.

Common stockholders are entitled to dividends if and when declared by the Company’s Board of Directors subject to the prior rights of the preferred stockholders. As of December 31, 2024 and 2023, no dividends on common stock had been declared by the Company’s Board of Directors.

Follow-on Offerings

In March 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 December 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 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.

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+ Details

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Prepaid expenses	$ 3,249	$ 3,263
Other current assets	2,735	1,619
Total prepaid expenses and other current assets	$ 5,984	$ 4,882

Basis of Presentation and Significant Accounting Polices - Additional Information (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) Segment
Accounting Policies [Line Items]
Product revenue \| $	$ 0
Contractual term of options granted	10 years
Employee stock purchase plan look-back period	6 months
Number of operating segments \| Segment	1
Minimum
Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Maximum
Accounting Policies [Line Items]
Estimated useful lives of assets	5 years
Contractual term of options granted	10 years

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Fair Value of Financial Instruments - Summary of Fair Value of Financial Instrument (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Assets:
Total cash equivalents	$ 27,873	$ 31,040
Total short-term investments	239,481	217,149
Total long-term investments	110,392
Total	377,185	247,900
Cash Equivalents
Assets:
Total cash equivalents	27,312
Short-term investments
Assets:
Total short-term investments	239,481	217,149
Long-Term Investments
Assets:
Total long-term investments	110,392
Money Market Funds \| Cash Equivalents
Assets:
Total cash equivalents	25,617	30,751
Commercial Paper \| Cash Equivalents
Assets:
Total cash equivalents	1,395
Commercial Paper \| Short-term investments
Assets:
Total short-term investments	22,820	38,197
U.S Government securities \| Cash Equivalents
Assets:
Total cash equivalents	300
U.S Government securities \| Short-term investments
Assets:
Total short-term investments	92,113	138,343
U.S Government securities \| Long-Term Investments
Assets:
Total long-term investments	24,130
Corporate Debt Securities \| Short-term investments
Assets:
Total short-term investments	124,548	40,609
Corporate Debt Securities \| Long-Term Investments
Assets:
Total long-term investments	86,262
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total	25,617	30,751
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Cash Equivalents
Assets:
Total cash equivalents	25,617
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds \| Cash Equivalents
Assets:
Total cash equivalents	25,617	30,751
Significant Other Observable Inputs (Level 2)
Assets:
Total	351,568	217,149
Significant Other Observable Inputs (Level 2) \| Cash Equivalents
Assets:
Total cash equivalents	1,695
Significant Other Observable Inputs (Level 2) \| Short-term investments
Assets:
Total short-term investments	239,481	217,149
Significant Other Observable Inputs (Level 2) \| Long-Term Investments
Assets:
Total long-term investments	110,392
Significant Other Observable Inputs (Level 2) \| Commercial Paper \| Cash Equivalents
Assets:
Total cash equivalents	1,395
Significant Other Observable Inputs (Level 2) \| Commercial Paper \| Short-term investments
Assets:
Total short-term investments	22,820	38,197
Significant Other Observable Inputs (Level 2) \| U.S Government securities \| Cash Equivalents
Assets:
Total cash equivalents	300
Significant Other Observable Inputs (Level 2) \| U.S Government securities \| Short-term investments
Assets:
Total short-term investments	92,113	138,343
Significant Other Observable Inputs (Level 2) \| U.S Government securities \| Long-Term Investments
Assets:
Total long-term investments	24,130
Significant Other Observable Inputs (Level 2) \| Corporate Debt Securities \| Short-term investments
Assets:
Total short-term investments	124,548	$ 40,609
Significant Other Observable Inputs (Level 2) \| Corporate Debt Securities \| Long-Term Investments
Assets:
Total long-term investments	$ 86,262

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets are comprised of the following (in thousands):


	December 31,
	2024		2023
Prepaid expenses	$	3,249	$	3,263
Other current assets		2,735		1,619
Total prepaid expenses and other current assets	$	5,984	$	4,882

Schedule of Property and Equipment, Net

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


	December 31,
	2024			2023
Leasehold improvements	$	66,618		$	66,618
Furniture and fixtures		746			745
Research equipment		16,914			14,298
Computers and software		404			404
Construction-in-progress		10,821			8,954
Total property and equipment, gross		95,503			91,019
Less accumulated depreciation and amortization		(20,845	)		(11,693	)
Total property and equipment, net	$	74,658		$	79,326

Schedule of Accrued Other Current Liabilities

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


	December 31,
	2024		2023
Accrued compensation	$	7,918	$	6,722
Accrued research and development costs		3,633		5,845
Accrued property and equipment		254		174
Other accrued and current liabilities		424		855
Total accrued and other liabilities	$	12,229	$	13,596

Net Loss Per Share - Summarizes the Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	10,237,105	7,311,294
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	9,069,194	6,716,526
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,167,911	594,768

Employee Benefits - Additional Information (Details) - 401 (K) Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, description	On January 1, 2018, the Company adopted a defined contribution 401(k) plan that is available to eligible employees.
Employer contribution, percent	3.00%
Expense contribution plan	$ 0.9	$ 1.0

Share-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Unit Activity - $ / shares	12 Months Ended
	Dec. 31, 2024	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	798,574
Number of shares, forfeited	(59,764)
Number of shares, Vested	(165,667)
Number of shares, outstanding ending balance	1,167,911	594,768
Weighted-average grant date fair value per share, outstanding beginning balance	$ 8.16
Weighted-average grant date fair value per share, granted	6.04	$ 5.57
Weighted-average grant date fair value per share, forfeited	6.8
Weighted-average grant date fair value per share, vested	8.63
Weighted-average grant date fair value per share, outstanding ending balance	$ 6.71	$ 8.16
Weighted-average remaining contractual term (in years), outstanding ending balance	1 year 4 months 24 days	1 year 4 months 24 days

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following table summarizes the stock option activity during the year ended December 31, 2024 (in thousands, except number of shares, exercise prices and contractual term):


	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		3,019,050			6.14
Exercised		(144,128	)		4.64
Forfeited		(522,254	)		17.96
Outstanding at December 31, 2024		9,069,194		$	10.55		7.0	$	263
Exercisable at December 31, 2024		4,899,150		$	14.01		6.0	$	108
Vested and expected to vest at December 31, 2024		9,069,194		$	10.55		7.0	$	263

Summary of Additional Information Related to Stock Options

Additional information related to the Company’s stock options is summarized below (in thousands, except per share amounts):


	Year Ended December 31,
	2024		2023
Weighted-average grant-date fair value of stock option grants per share	$	5.02	$	3.36
Intrinsic value of options exercised	$	798	$	39

Summary of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity during the year ended December 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		798,574			6.04
Forfeited		(59,764	)		6.80
Vested		(165,667	)		8.63
Outstanding at December 31, 2024		1,167,911		$	6.71		1.4

Summary of Common Stock Reserved For Future Issuance

As of December 31, 2024, the Company had reserved the following shares of common stock for future issuance:


	December 31, 2024
Common stock options and restricted stock units granted and outstanding		10,237,105
Reserved for future equity award grants		1,868,770
Reserved for future ESPP issuances		1,562,749
		13,668,624

Summary of Share-based Compensation Expense

Share-based compensation expense for the years ended December 31, 2024 and 2023 were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Research and development	$	7,955	$	8,025
General and administrative		8,776		9,174
Total share-based compensation expense	$	16,731	$	17,199

Schedule of Fair Value of Stock Options Estimated on Date of Grant Using Quoted Market Price For Common Stock On The Applicable Grant Date And Black-Scholes Option Pricing Model

The fair value of stock options was estimated on the date of grant using the quoted market price for the Company’s common stock on the applicable grant date and the Black-Scholes option pricing model with the following range of assumptions:


	Year Ended December 31,
	2024	2023
Options
Risk-free interest rate	3.5% - 4.5%	3.5% - 4.9%
Expected volatility	100.4% - 117.3%	90.0% - 101.8%
Expected term (in years)	5.5 - 6.1	5.5 - 6.1
Expected dividend yield	—	—
ESPP
Risk-free interest rate	4.4% - 5.4%	4.7% - 5.4%
Expected volatility	83.2% - 152.7%	63.8% - 152.7%
Expected term (in years)	0.5	0.5
Expected dividend yield	—	—

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principle ("U.S. GAAP").
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, but not limited to, 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.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash, cash equivalents and investments. The Company maintains cash, cash equivalents and investments with various high credit quality and are invested through banks and other financial institutions in the United States. Such deposits may be in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has not experienced any losses on deposits since inception.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on investments. The Company displays comprehensive loss and its components as part of the statements of operations and comprehensive loss.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The accounting guidance defines fair value, establishes a consistent framework for measuring fair value, and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of prepaid expenses and other current assets, accounts payable, accrued liabilities and other current liabilities are reasonable estimates of their fair value due to the short-term nature of these accounts.
Cash, Cash Equivalents, Investments and Restricted Cash	Cash, Cash Equivalents, Investments and Restricted Cash Cash and Cash Equivalents The Company considers all highly liquid investments with insignificant interest rate risk and an original maturity of three months or less at the date of purchase to be cash equivalents. Cash includes demand deposits held in readily available checking accounts at a federally insured financial institution. Cash equivalents consist of money market funds, commercial paper, and U.S. Government securities. Investments Investments consist of corporate debt securities, commercial paper and Government securities, classified as available-for-sale securities and have maturities of greater than three months. The Company has classified its available-for-sale investment securities with maturities less than one year as current assets on the balance sheets because these are considered highly liquid securities and are available for use in current operations and its available-for-sale investment securities with maturities more than one year as non-current assets on the balance sheets. The Company carries these securities at fair value, and reports unrealized gains and losses as a separate component of accumulated other comprehensive income (loss). The cost of debt securities is adjusted for amortization of purchase premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income in the statements of operations and comprehensive loss. Realized gains and losses on sales of securities are determined using the specific identification method and recorded in other income, net in the statement of operations and comprehensive loss. We review our portfolio of available-for-sale securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, we recognize a loss in the statement of operations, whereas if the decline in fair value is not due to credit-related factors, we recognize the loss in comprehensive loss. Restricted Cash The Company is required to maintain letters of credit related to its office and lab space leases in South San Francisco. This cash is the collateral for those letters of credit and per the terms of the leases, must remain in place until one to two months after the termination of the leases. As the remaining terms of the leases as of December 31, 2024 is greater than one year, the related restricted cash has been classified as non-current.
Property and Equipment, Net	Property and Equipment, Net Property and equipment, which consist of leasehold improvements, furniture and fixtures, research equipment, computers and software and construction-in-progress are stated at cost less accumulated depreciation. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which ranges from three to five years. Leasehold improvements are amortized over the remaining life of the lease at the time the asset is placed into service.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The carrying value of long-lived assets, including property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the asset may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. See Note 6 for additional information on the long-lived asset impairment expense recognized for the year ended December 31, 2023.
Collaborative Arrangements	Collaborative Arrangements The Company analyzes its collaboration arrangements to assess whether they are within the scope of Accounting Standards Codification ("ASC") Topic 808, Collaborative Arrangements ("ASC 808"), to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of ASC 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC Topic 606, Revenue from Contracts with Customers ("ASC 606"). If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs consist primarily of salaries and other benefits of research and development personnel, including associated share-based compensation, costs related to research activities, preclinical studies, clinical trial, drug manufacturing and allocated overhead and facility-related expenses. The Company accounts for non-refundable advance payments for goods or services that will be used in future research and development activities as expenses when the goods have been received or when the service has been performed rather than when the payment is made. Clinical trial costs are a component of research and development expenses. The Company expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, as they are incurred, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company uses information it receives from internal personnel and outside service providers to estimate the clinical trial costs incurred.
Leases	Leases At the commencement date of a lease, the Company recognizes lease liabilities which represent its obligation to make lease payments, and right-of-use assets ("ROU assets") which represent its right to use the underlying asset during the lease term. The lease liability is measured at the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at the lease commencement date. The ROU asset is measured at cost, which includes the initial measurement of the lease liability and initial direct costs incurred by the Company and excludes lease incentives. ROU assets are recorded in operating lease ROU assets and lease liabilities are recorded in operating lease liabilities, current and noncurrent in the balance sheets. We have elected the practical expedient to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component for our facilities leases, and elected the short-term lease recognition exemption for our short-term leases, under which we do not recognize lease liabilities and ROU assets for leases with an original term of twelve months or less. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term. The Company does not recognize lease liabilities and ROU assets for short-term leases with terms of twelve months or less.
Share-Based Compensation	Share-Based Compensation Share-based compensation expense represents the cost of the grant-date fair value of employee, officer, director, and non-employee stock option, employee stock purchase plan, and restricted stock unit grants, estimated in accordance with the applicable accounting guidance, recognized using the straight-line method over the vesting period for service-based options, employee stock purchase plan rights and restricted stock units and using the graded vesting method for performance-based options. The vesting period generally approximates the expected service period of the awards. Forfeitures are recognized and accounted for as they occur. The fair value of stock options and employee stock purchase plan rights are estimated using a Black-Scholes option pricing model on the date of grant. This method requires certain assumptions be used as inputs, such as the fair value of the underlying common stock, expected term of the option before exercise, expected volatility of the Company’s common stock, expected dividend yield, and a risk-free interest rate. Options granted during the year have a maximum contractual term of ten years. The Company has limited historical stock option activity and therefore estimates the expected term of stock options granted using the simplified method, which represents the average of the contractual term of the stock option and its weighted-average vesting period. The expected term of the employee stock purchase plan rights equals the six-month look-back period. The expected volatility is determined by using a blended approach of the Company's historical stock price volatility and the historical stock price volatility for a select group of other publicly traded companies in the same industry. The Company has historically not declared or paid any dividends and does not currently expect to do so in the foreseeable future. The risk-free interest rates used are based on the U.S. Department of Treasury ("U.S. Treasury") yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the stock options. The fair value of restricted stock units is based on the closing price of the Company's common stock as reported on The Nasdaq Global Select Market on the date of grant.
Income Taxes	Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applicable to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.
Segment Reporting	Segment Reporting The Company’s chief operating decision maker ("CODM"), its Chief Executive Officer, manages its operations and business as one operating segment for the purposes of allocating resources, makes operating decisions and evaluates financial performance. No product revenue has been generated since inception and all assets are held in the United States.
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 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 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, unvested restricted stock options, and outstanding stock options under the Company’s equity incentive plans, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Adopted 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. The Company adopted this standard in the fiscal year beginning January 1, 2024. There was no impact on the Company’s reportable segments identified and additional required disclosures have been included in Note 13. 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 did not have a material impact on the financial position, results of operations or cash flows of the Company. Accounting Pronouncements Not Yet Adopted 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 November 2024, the FASB issued ASU 2024-03, "Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses". ASU 2024-03 requires public entities to disclose specified information about certain costs and expenses on an interim and annual basis and is effective for annual reporting periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted. The new standard is expected to be applied prospectively, but retrospective application is permitted. The Company is currently evaluating the impact of ASU 2024-03 on the financial statements and related disclosures. 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.

Segment Reporting - Summary of Reconciliation to Net Loss (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2024
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Segment Reporting, Other Segment Item, Composition, Description	Other segment items include consultants and contractor, lab supplies, and general business expenses.

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	54,350,179	54,350,179
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	100,000,000
Common stock, shares issued	70,645,139	49,181,295
Common stock, shares outstanding	70,645,139	49,181,295

Balance Sheet Components

12 Months Ended

Dec. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets are comprised of the following (in thousands):


	December 31,
	2024		2023
Prepaid expenses	$	3,249	$	3,263
Other current assets		2,735		1,619
Total prepaid expenses and other current assets	$	5,984	$	4,882

Property and Equipment, Net

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


	December 31,
	2024			2023
Leasehold improvements	$	66,618		$	66,618
Furniture and fixtures		746			745
Research equipment		16,914			14,298
Computers and software		404			404
Construction-in-progress		10,821			8,954
Total property and equipment, gross		95,503			91,019
Less accumulated depreciation and amortization		(20,845	)		(11,693	)
Total property and equipment, net	$	74,658		$	79,326

Depreciation and amortization expense were $9.2 million and $5.9 million for the years ended December 31, 2024 and 2023, respectively.

Accrued and Other Current Liabilities

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


	December 31,
	2024		2023
Accrued compensation	$	7,918	$	6,722
Accrued research and development costs		3,633		5,845
Accrued property and equipment		254		174
Other accrued and current liabilities		424		855
Total accrued and other liabilities	$	12,229	$	13,596

Net Loss Per Share (Tables)

12 Months Ended

Dec. 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):


	Year Ended December 31,
	2024			2023
Numerator:
Net loss	$	(108,790	)	$	(117,501	)
Denominator:
Weighted average common shares outstanding		65,570,217			49,014,357
Less: weighted average unvested common stock issued upon early exercise of common stock options		—			(57	)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants		2,295,106			—
Weighted average shares used to compute net loss per share, basic and diluted		67,865,323			49,014,300
Net loss per share, basic and diluted	$	(1.60	)	$	(2.40	)

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 anti-dilutive:


	December 31,
	2024		2023
Common stock options		9,069,194		6,716,526
Restricted stock units		1,167,911		594,768
		10,237,105		7,311,294

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
2025	$ 12,537
2026	12,621
2027	13,041
2028	13,477
2029	13,927
2030 and thereafter	57,458
Total undiscounted future minimum lease payments	123,061
Less imputed interest	(42,788)
Total operating lease liabilities	80,273
Operating lease liabilities:
Operating lease liabilities, current portion	6,050	$ 6,069
Operating lease liabilities, net of current portion	74,223	$ 82,270
Total lease liability	$ 80,273

Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Statement of Stockholders' Equity [Abstract]
Issuance costs	$ 15,027

Leases

12 Months Ended

Dec. 31, 2024

Leases [Abstract]

Leases

6. Leases

The Company has operating leases for its current corporate offices, laboratory space, manufacturing facility, and dedicated space in a vivarium in South San Francisco, California.

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease expense	$	10,578	$	10,900
Variable lease expense (1)		1,247		1,018
Short-term lease expense		—		18
Total lease expense	$	11,825	$	11,936

(1) Variable lease expense for the periods presented primarily included common area maintenance charges.

Supplemental information related to operating leases were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$	14,680	$	11,540

The weighted-average remaining lease term was 9.0 years for the corporate office and laboratory space leases as of December 31, 2024. The corporate office lease includes an option to renew for an additional seven years. However, the renewal option was not included in the lease term for calculating the lease liability, as the renewal option allows the Company to maintain operational flexibility, and the Company was not reasonably certain that it would exercise the renewal option at the time of the lease commencement. The weighted-average discount rate was 9.8% as of December 31, 2024.

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


Year ending December 31,	Amount
2025	$	12,537
2026		12,621
2027		13,041
2028		13,477
2029		13,927
2030 and thereafter		57,458
Total undiscounted future minimum lease payments		123,061
Less imputed interest		(42,788	)
Total operating lease liabilities	$	80,273
Operating lease liabilities:
Current		6,050
Non-current		74,223
Total lease liability	$	80,273

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. In December 2024, the Company executed a sixth amendment to the Initial Lease Agreement, which updated the lease termination date for one of the spaces in the same building to July 31, 2025. In connection with the amendment, the Company agreed to pay the landlord a termination fee of $1.1 million, $0.6 million of which was paid in December

2024 and the remaining will be paid by July 2025. As a result of the modification, the Company decreased its right-of-use asset and lease liability each by $2.2 million.

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.

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 ROU assets and certain property, plant and equipment, primarily for leasehold improvements (collectively, "Sublease Asset Group"). The Company estimated potential sublease income using unobservable 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 ROU 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 using the estimated borrowing rate of a market participant subtenant which we estimated to be 8%. The carrying value of the Sublease Asset Group exceeded its fair values and, as a result, the Company recorded an ROU asset impairment of $4.1 million for the year ended December 31, 2023. The impairment is recorded within general and administrative expenses in the statements of operations and comprehensive loss. No additional impairment has been recorded.

Sublease Agreements

In September 2024 and November 2024, the Company entered into agreements to sublease a portion of the Company's leased corporate office space through November 2027 and July 2030, respectively. The sublease agreements both commenced during the fourth quarter of 2024 and rent payments will commence in 2025. The Company accounts for the sublease agreements in accordance with ASC 842, Leases. Sublease income during the year ended December 31, 2024, was not material.

Fair Value of Financial Instruments - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments sold	$ 67,600,000
Realized loss on investments	$ 300,000
Investments sold prior to their maturity date		$ 0
Realized gain or loss on available-for-sale securities			$ 34,000
Accrued interest receivable		2,500,000	1,200,000
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		$ 25,600,000	$ 30,800,000

Leases (Tables)

12 Months Ended

Dec. 31, 2024

Leases [Abstract]

Components of Lease Expense

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease expense	$	10,578	$	10,900
Variable lease expense (1)		1,247		1,018
Short-term lease expense		—		18
Total lease expense	$	11,825	$	11,936

(1) Variable lease expense for the periods presented primarily included common area maintenance charges.

Schedule of Supplemental Information Related to Operating Leases

Supplemental information related to operating leases were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$	14,680	$	11,540

Schedule of Maturities of Operating Lease Liabilities

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


Year ending December 31,	Amount
2025	$	12,537
2026		12,621
2027		13,041
2028		13,477
2029		13,927
2030 and thereafter		57,458
Total undiscounted future minimum lease payments		123,061
Less imputed interest		(42,788	)
Total operating lease liabilities	$	80,273
Operating lease liabilities:
Current		6,050
Non-current		74,223
Total lease liability	$	80,273

Share-Based Compensation - Schedule of Fair Value of Stock Options Estimated on Date of Grant Using Quoted Market Price For Common Stock On The Applicable Grant Date And Black-Scholes Option Pricing Model (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.50%	3.50%
Risk-free interest rate, maximum	4.50%	4.90%
Expected volatility, minimum	100.40%	90.00%
Expected volatility, maximum	117.30%	101.80%
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	4.40%	4.70%
Risk-free interest rate, maximum	5.40%	5.40%
Expected volatility, minimum	83.20%	63.80%
Expected volatility, maximum	152.70%	152.70%
Expected term (in years)	6 months	6 months
Minimum \| Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 6 months
Maximum \| Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Collaboration and License Agreements - Additional Information (Details)		1 Months Ended		12 Months Ended
	Oct. 26, 2021 USD ($)	Aug. 31, 2016 SGD ($) shares	Aug. 31, 2016 USD ($) shares	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development costs				$ 96,744,000	$ 96,773,000
Research Collaboration Agreement \| Development and Regulatory Approval Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Reduction of research and development expense resulting from partial reimbursement				$ 100,000	1,600,000
Potential future payments				totaling less than mid-twenty million dollars
Amount paid under the agreement				$ 0
Amounts owed under the agreement				0
Receivable under research cost sharing provision				200,000	200,000
MaxCyte License Agreement \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments	$ 10,000,000
Net sales milestone payments	61,900,000
Annual research license fees and Commercialization license fees	100,000
MaxCyte License Agreement \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone payments	13,000,000
Net sales milestone payments	116,800,000
Annual research license fees and Commercialization license fees	$ 300,000
NUS and St. Jude \| License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment		$ 42,750	$ 31,800
Upfront payment, shares issued \| shares		250,000	250,000
Fair value of common stock issued			$ 2,500
Annual license maintenance fee		$ 25,000
Potential milestone payments		$ 5,000,000
Percentage of licensors royalties		2.50%	2.50%
NUS and St. Jude \| License Agreement \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of sublicensing income		7.50%	7.50%
NUS and St. Jude \| License Agreement \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of sublicensing income		20.00%	20.00%
License agreement term		120 months	120 months
NUS and St. Jude \| License Maintenance Fees \| License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development costs				$ 37,000	$ 37,000
NUS and St. Jude \| After Year Two of the Agreement \| License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual license maintenance fee		$ 50,000

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Lease, Cost [Abstract]
Operating lease expense	$ 10,578	$ 10,900
Variable lease expense	1,247	1,018
Short-term lease expense		18
Total lease expense	$ 11,825	$ 11,936

Leases - Additional Information (Details) - USD ($)	1 Months Ended						12 Months Ended
Leases - Additional Information (Details) - USD ($)	Dec. 31, 2024	Jun. 30, 2023	Oct. 31, 2021	Jan. 31, 2021	May 31, 2020	May 31, 2018	Dec. 31, 2024	Dec. 31, 2023	Jul. 31, 2021
Lessee Lease Description [Line Items]
Weighted-average discount rate	9.80%						9.80%
Lessee, operating lease, term of contract									12 years
Lease liabilities	$ 80,273,000						$ 80,273,000
Right-of-use assets	$ 36,014,000						36,014,000	$ 39,949,000
Additional tenant improvement allowances		$ 4,400,000
Tenant improvement costs in equal monthly payments annual rate		8.50%
ROU asset impairment							$ 0	$ 4,100,000
Estimated subtenant rate	8.00%						8.00%
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]
Operating lease, existence of option to extend			true		true
Lease expiration year						2025
Initial Lease Agreement \| Sixth Amendment
Lessee Lease Description [Line Items]
Termination fee payment to landlord	$ 600,000						$ 1,100,000
Decrease in right-of-use asset	2,200,000
Decrease in lease liability	$ 2,200,000
Corporate Office and Laboratory Space
Lessee Lease Description [Line Items]
Weighted-average remaining lease term	9 years						9 years
Corporate Office and Laboratory Space \| Sixth Amendment
Lessee Lease Description [Line Items]
Lessee option to extend description	In December 2024, the Company executed a sixth amendment to the Initial Lease Agreement, which updated the lease termination date for one of the spaces in the same building to July 31, 2025.
Corporate Office and Laboratory Space \| Initial Lease Agreement
Lessee Lease Description [Line Items]
Renewal term						7 years
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.

Reduction in Force

12 Months Ended

Dec. 31, 2024

Reduction in Force [Abstract]

Reduction in Force

14. Reduction in Force

On October 16, 2023, the Company committed to cost saving measures, including a reduction in force (the "2023 Reduction") that resulted in a reduction of 18 positions, representing approximately 10% of the Company’s workforce. The Company undertook the 2023 Reduction to decrease its costs and create a more streamlined organization to support its operations through multiple clinical data updates.

In connection with the 2023 Reduction, the Company incurred $1.2 million in costs, consisting primarily of cash severance costs and transition support services for impacted employees, which the Company recognized in the fourth quarter of 2023 in general and administrative operating expenses in the statement of operations. As of December 31, 2023, $0.8 million was paid out and $0.4 million was recorded under other accrued and other current liabilities. There were no remaining liabilities as of December 31, 2024.

On March 26, 2025, the Company committed to cost saving measures, including a reduction in force (the "2025 Reduction") that will result in a reduction of 53 positions, representing approximately 34% of the Company’s workforce. The Company undertook the 2025 Reduction to decrease its costs and create a more streamlined organization to focus on upcoming clinical data updates.

In connection with the implementation of the 2025 Reduction, the Company currently estimates it will incur approximately $5.5 million to $6.5 million in costs, consisting primarily of cash severance costs, benefits, payroll taxes and other termination costs for impacted employees, which the Company expects to recognize primarily in the first quarter of 2025.

Reduction in Force - Additional Information (Details)			12 Months Ended
Reduction in Force - Additional Information (Details)	Mar. 26, 2025 USD ($) Employee	Oct. 16, 2023 USD ($) Employee	Dec. 31, 2023 USD ($)	Dec. 31, 2024 USD ($)
Reduction in Force [Line Items]
Number of position reduced \| Employee		18
Percentage of reduction		10.00%
Reduction costs		$ 1,200,000
Reduction initiation date		Oct. 16, 2023
Payments for restructuring			$ 800,000
Restructuring reserve			$ 400,000	$ 0
Subsequent Event
Reduction in Force [Line Items]
Number of position reduced \| Employee	53
Percentage of reduction	34.00%
Reduction initiation date	Mar. 26, 2025
Minimum \| Subsequent Event
Reduction in Force [Line Items]
Reduction costs	$ 5,500,000
Maximum \| Subsequent Event
Reduction in Force [Line Items]
Reduction costs	$ 6,500,000

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 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
	December 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	$	25,617	$	25,617	$	—	$	—
Commercial paper		1,395		—		1,395		—
Government securities		300		—		300		—
Total cash equivalents	$	27,312	$	25,617	$	1,695	$	—
Short-term investments:
Corporate debt securities	$	124,548	$	—	$	124,548	$	—
Commercial paper		22,820		—		22,820		—
Government securities		92,113		—		92,113		—
Total short-term investments	$	239,481	$	—	$	239,481	$	—
Long-term investments:
Corporate debt securities	$	86,262	$	—	$	86,262	$	—
Government securities		24,130		—		24,130		—
Total long-term investments	$	110,392	$	—	$	110,392	$	—
Total	$	377,185	$	25,617	$	351,568	$	—


			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
U.S. Government securities		138,343		—		138,343		—
Total short-term investments	$	217,149	$	—	$	217,149	$	—
Total	$	247,900	$	30,751	$	217,149	$	—

Short-term investments

Schedule of Investments

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


		December 31, 2024
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	124,283	$	(38	)	$	303	$	124,548
Commercial paper	1 year or less		22,820		—			—		22,820
Government securities	1 year or less		92,013		(17	)		117		92,113
Corporate debt securities	Greater than 1 year		85,992		(62	)		332		86,262
Government securities	Greater than 1 year		24,091		(29	)		68		24,130
Total		$	349,199	$	(146	)	$	820	$	349,873


		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
U.S. 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
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Section 50
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
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-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Share-Based Compensation - Summary of Stock Option Activity (Details) - Equity Incentive Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 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	3,019,050
Number of shares, exercised	(144,128)
Number of shares, forfeited	(522,254)
Number of shares, outstanding ending balance	9,069,194	6,716,526
Number of shares, exercisable	4,899,150
Number of shares, vested and expected to vest	9,069,194
Weighted-average exercise price, outstanding beginning balance	$ 12.99
Weighted-average exercise price, granted	6.14
Weighted-average exercise price, exercised	4.64
Weighted-average exercise price, forfeited	17.96
Weighted-average exercise price, outstanding ending balance	10.55	$ 12.99
Weighted-average exercise price, exercisable	14.01
Weighted-average exercise price, vested and expected to vest	$ 10.55
Weighted-average remaining contractual term (in years), outstanding balance	7 years	7 years 6 months
Weighted-average remaining contractual term (in years), exercisable	6 years
Weighted-average remaining contractual term (in years), vested and expected to vest	7 years
Aggregate intrinsic value, outstanding balance	$ 263	$ 8,279
Aggregate intrinsic value, exercisable	108
Aggregate intrinsic value, vested and expected to vest	$ 263

Income Taxes - Reconciliation on Income Taxes Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income tax benefit at statutory rates	$ (22,846,000)	$ (24,675,000)
State income tax, net of federal benefit	(1,701,000)	(1,438,000)
Permanent items	2,877,000	1,656,000
Research and development credits	(3,640,000)	(6,170,000)
Change in valuation allowance	25,310,000	30,627,000
Income tax expense	$ 0	$ 0

- Definition

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

+ References

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

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued compensation	$ 7,918	$ 6,722
Accrued research and development costs	3,633	5,845
Accrued property and equipment	254	174
Other accrued and current liabilities	424	855
Total accrued and other liabilities	$ 12,229	$ 13,596

Share-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate cash proceeds	$ 343,000	$ 530,000
Number of common stock available for new award grants	13,668,624
Unrecognized compensation cost	$ 19,400,000
Unrecognized compensation cost, expected to be recognized over weighted average remaining service period	2 years 7 months 6 days
Contractual term of options granted	10 years
Dividends issued for options	$ 0
Dividends expected to be issued over life of options	$ 0
Estimated dividend yield	0.00%
Weighted-average grant-date fair value of stock option grants per share	$ 5.02	$ 3.36
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	$ 5,600,000
Unrecognized compensation cost, expected to be recognized over weighted average remaining service period	2 years 7 months 6 days
Weighted-average grant date fair value per share, granted	$ 6.04	$ 5.57
Fair value of restricted stock units vested	$ 1,400,000	$ 400,000
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	144,049	164,567
Aggregate cash proceeds	$ 300,000	$ 500,000
Number of common stock available for new award grants	1,562,749
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%
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 new award grants	1,868,770

Fair Value of Financial Instruments

12 Months Ended

Dec. 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
	December 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	$	25,617	$	25,617	$	—	$	—
Commercial paper		1,395		—		1,395		—
Government securities		300		—		300		—
Total cash equivalents	$	27,312	$	25,617	$	1,695	$	—
Short-term investments:
Corporate debt securities	$	124,548	$	—	$	124,548	$	—
Commercial paper		22,820		—		22,820		—
Government securities		92,113		—		92,113		—
Total short-term investments	$	239,481	$	—	$	239,481	$	—
Long-term investments:
Corporate debt securities	$	86,262	$	—	$	86,262	$	—
Government securities		24,130		—		24,130		—
Total long-term investments	$	110,392	$	—	$	110,392	$	—
Total	$	377,185	$	25,617	$	351,568	$	—


			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
U.S. 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, commercial paper, and Government securities and investments consisted of commercial paper, corporate debt securities and Government securities. The Company obtains pricing information from its investment manager and 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 $25.6 million and $30.8 million included in cash equivalents as of December 31, 2024 and 2023, respectively, were classified as Level 1 instruments.

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 following tables summarize the Company’s investments as of December 31, 2024 and 2023 (in thousands):


		December 31, 2024
	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
Corporate debt securities	1 year or less	$	124,283	$	(38	)	$	303	$	124,548
Commercial paper	1 year or less		22,820		—			—		22,820
Government securities	1 year or less		92,013		(17	)		117		92,113
Corporate debt securities	Greater than 1 year		85,992		(62	)		332		86,262
Government securities	Greater than 1 year		24,091		(29	)		68		24,130
Total		$	349,199	$	(146	)	$	820	$	349,873


		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
U.S. Government securities	1 year or less		138,341		(56	)		58		138,343
Total		$	217,141	$	(69	)	$	77	$	217,149

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 December 31, 2024 and 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 December 31, 2024 and 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, except for investments totaling $67.6 million that were sold with a realized loss of $0.3 million in January 2023. No investments were sold prior to their maturity date during 2024. Unrealized gains and losses are included in accumulated other comprehensive income (loss).

The Company excludes accrued interest from both the fair value and the amortized cost basis of the available-for-sale debt securities for the purposes of identifying and measuring an impairment and to not measure an allowance for expected credit losses for accrued interest receivables. Accrued interest receivable is written off through net realized investment gains (losses) at the time the issuer of the bond defaults or is expected to default on payment. It is the Company's policy to present the accrued interest receivable balance as part of prepaid expenses and other current assets in the balance sheets. Accrued interest receivable related to investments was $2.5 million and $1.2 million as of December 31, 2024 and 2023, respectively.

- 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

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+ Details

Share-Based Compensation - Summary of Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2024 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	13,668,624
Reserved for Future ESPP Issuances
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,562,749
Reserved for Future Equity Award Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,868,770
Common Stock Options And Restricted Stock Units Granted And Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	10,237,105

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

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 Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2022	$ 372,207		$ 5		$ 690,814		$ (317,933)	$ (679)
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			508
Issuance of common stock upon exercise of stock options	161				161
Issuance of common stock upon exercise of stock options, Shares			49,871
Issuance of common stock upon vesting of restricted stock units, Shares			88,543
Issuance of common stock under employee stock purchase plan	530				530
Issuance of common stock under employee stock purchase plan, Shares			164,567
Share-based compensation expense	17,199				17,199
Net unrealized gain on investments	687							687
Net loss	(117,501)						(117,501)
Ending Balance at Dec. 31, 2023	273,285		$ 5		708,706		(435,434)	8
Ending Balance, Shares at Dec. 31, 2023			49,181,295
Issuance of common stock, net of issuance costs		$ 225,073		$ 2		$ 225,071
Issuance of common stock, net of issuance costs, Shares				21,010,000
Issuance of common stock upon exercise of stock options	668				668
Issuance of common stock upon exercise of stock options, Shares			144,128
Issuance of common stock upon vesting of restricted stock units, Shares			165,667
Issuance of common stock under employee stock purchase plan	343				343
Issuance of common stock under employee stock purchase plan, Shares			144,049
Share-based compensation expense	16,731				16,731
Net unrealized gain on investments	666							666
Net loss	(108,790)						(108,790)
Ending Balance at Dec. 31, 2024	$ 407,976		$ 7		$ 951,519		$ (544,224)	$ 674
Ending Balance, Shares at Dec. 31, 2024			70,645,139

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Jun. 13, 2024	Jun. 12, 2024
Class Of Stock [Line Items]
Common stock, shares authorized		200,000,000	100,000,000	200,000,000	100,000,000
Common stock, par value		$ 0.0001	$ 0.0001	$ 0.0001
Dividends on common stock declared		$ 0	$ 0
Preferred stock, shares authorized		54,350,179	54,350,179
Preferred stock, par value		$ 0.0001	$ 0.0001
Payments of Stock Issuance Costs		$ 15,027
Pre-funded warrant
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs		$ 225,073
Follow On Offerings
Class Of Stock [Line Items]
Payments of Stock Issuance Costs	$ 14,400
Other offering expenses	600
Follow-on Offerings
Class Of Stock [Line Items]
Net proceeds from offering	$ 240,100
Follow-on Offerings \| Pre-funded warrant
Class Of Stock [Line Items]
Stock public offering price	$ 9.9999
Pre-funded warrants to purchase shares of common stock	3,000,031
Exercise price of warrants	$ 0.0001
Common Stock \| Pre-funded warrant
Class Of Stock [Line Items]
Common stock shares issued and sold		21,010,000
Issuance of common stock, net of issuance costs		$ 2
Common Stock \| Follow-on Offerings
Class Of Stock [Line Items]
Common stock shares issued and sold	21,010,000
Stock public offering price	$ 10

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 95,503	$ 91,019
Less accumulated depreciation and amortization	(20,845)	(11,693)
Total property and equipment, net	74,658	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	16,914	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	$ 10,821	$ 8,954

Share-Based Compensation - Summary of Additional Information Related to Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Weighted-average grant-date fair value of stock option grants per share	$ 5.02	$ 3.36
Intrinsic value of options exercised	$ 798	$ 39

Income Taxes - Summary of Changes in Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Balance at the beginning of the year	$ 3,738	$ 2,339
Increases (decreases) related to tax positions taken in prior years	(83)	102
Increases related to tax positions taken in current year	1,093	1,297
Balance at the end of the year	$ 4,748	$ 3,738

Fair Value of Financial Instruments - Schedule of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities, Amortized Cost	$ 349,199	$ 217,141
Available for sale securities, Unrealized Losses	(146)	(69)
Available for sale securities, Unrealized Gains	820	77
Available for sale securities,Estimated Fair Value	349,873	217,149
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available for sale securities 1 year or less, Amortized Cost	124,283	40,602
Available for sale securities greater than 1 year, Amortized Cost	85,992
Available for sale securities 1 year or less, Unrealized Losses	(38)	(11)
Available for sale securities greater than 1 year, Unrealized Losses	(62)
Available for sale securities 1 year or less, Unrealized Gains	303	18
Available for sale securities greater than 1 year, Estimated Fair Value	332
Available for sale securities 1 year or less, Estimated Fair Value	124,548	$ 40,609
Available for sale securities greater than 1 year, Estimated Fair Value	$ 86,262
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 \| 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 1 year or less, Amortized Cost	$ 22,820	$ 38,198
Available for sale securities 1 year or less, Unrealized Losses		(2)
Available for sale securities 1 year or less, Unrealized Gains		1
Available for sale securities 1 year or less, Estimated Fair Value	$ 22,820	$ 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 1 year or less, Amortized Cost	$ 92,013	$ 138,341
Available for sale securities greater than 1 year, Amortized Cost	24,091
Available for sale securities 1 year or less, Unrealized Losses	(17)	(56)
Available for sale securities greater than 1 year, Unrealized Losses	(29)
Available for sale securities 1 year or less, Unrealized Gains	117	58
Available for sale securities greater than 1 year, Estimated Fair Value	68
Available for sale securities 1 year or less, Estimated Fair Value	92,113	$ 138,343
Available for sale securities greater than 1 year, Estimated Fair Value	$ 24,130
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
U.S. Government securities \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Maturity (in years)	1 year

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 27,873	$ 31,040
Short-term investments	239,481	217,149
Prepaid expenses and other current assets	5,984	4,882
Total current assets	273,338	253,071
Long-term investments	110,392
Restricted cash	2,743	2,743
Property and equipment, net	74,658	79,326
Operating lease right-of-use assets	36,014	39,949
Other long-term assets	4,058	3,796
Total assets	501,203	378,885
Current liabilities:
Accounts payable	638	3,665
Operating lease liabilities, current portion	6,050	6,069
Accrued and other current liabilities	12,229	13,596
Total current liabilities	18,917	23,330
Operating lease liabilities, net of current portion	74,223	82,270
Other long-term liabilities	87
Total liabilities	93,227	105,600
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.0001 par value; 54,350,179 shares authorized; no shares issued and outstanding at December 31, 2024 and 2023
Common stock, $0.0001 par value; 200,000,000 and 100,000,000 shares authorized as of December 31, 2024 and 2023, respectively; 70,645,139 and 49,181,295 shares issued and outstanding at December 31, 2024 and 2023, respectively	7	5
Additional paid-in capital	951,519	708,706
Accumulated other comprehensive income (loss)	674	8
Accumulated deficit	(544,224)	(435,434)
Total stockholders' equity	407,976	273,285
Total liabilities and stockholders' equity	$ 501,203	$ 378,885

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Operating expenses:
Research and development	$ 96,744	$ 96,773
General and administrative	31,450	34,877
Total operating expenses	128,194	131,650
Loss from operations	(128,194)	(131,650)
Other income, net:
Interest income	19,317	14,107
Other income, net	87	42
Total other income, net	19,404	14,149
Net loss	(108,790)	(117,501)
Comprehensive loss:
Net Income (Loss)	(108,790)	(117,501)
Other comprehensive loss:
Net unrealized gain on investments	666	687
Comprehensive loss	$ (108,124)	$ (116,814)
Net loss per share, basic	$ (1.6)	$ (2.4)
Net loss per share, diluted	$ (1.6)	$ (2.4)
Weighted average shares outstanding used in computing net loss per share, basic	67,865,323	49,014,300
Weighted average shares outstanding used in computing net loss per share, diluted	67,865,323	49,014,300

Leases - Schedule of Supplemental Information Related to Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$ 14,680	$ 11,540

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Numerator:
Net loss	$ (108,790)	$ (117,501)
Denominator:
Weighted average common shares outstanding	65,570,217	49,014,357
Less: weighted average unvested common stock issued upon early exercise of common stock options		(57)
Add: weighted average of common stock to be issued upon exercise of pre-funded warrants	2,295,106
Weighted average shares used to compute net loss per share, basic	67,865,323	49,014,300
Weighted average shares used to compute net loss per share, diluted	67,865,323	49,014,300
Net loss per share, basic	$ (1.6)	$ (2.4)
Net loss per share, diluted	$ (1.6)	$ (2.4)

Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 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 financial statements have been prepared in accordance with U.S. generally accepted accounting principle ("U.S. GAAP"). 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, but not limited to, 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. Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash, cash equivalents and investments. The Company maintains cash, cash equivalents and investments with various high credit quality and are invested through banks and other financial institutions in the United States. Such deposits may be in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has not experienced any losses on deposits since inception. Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on investments. The Company displays comprehensive loss and its components as part of the statements of operations and comprehensive loss. Fair Value of Financial Instruments The accounting guidance defines fair value, establishes a consistent framework for measuring fair value, and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of prepaid expenses and other current assets, accounts payable, accrued liabilities and other current liabilities are reasonable estimates of their fair value due to the short-term nature of these accounts. Cash, Cash Equivalents, Investments and Restricted Cash Cash and Cash Equivalents The Company considers all highly liquid investments with insignificant interest rate risk and an original maturity of three months or less at the date of purchase to be cash equivalents. Cash includes demand deposits held in readily available checking accounts at a federally insured financial institution. Cash equivalents consist of money market funds, commercial paper, and U.S. Government securities. Investments Investments consist of corporate debt securities, commercial paper and Government securities, classified as available-for-sale securities and have maturities of greater than three months. The Company has classified its available-for-sale investment securities with maturities less than one year as current assets on the balance sheets because these are considered highly liquid securities and are available for use in current operations and its available-for-sale investment securities with maturities more than one year as non-current assets on the balance sheets. The Company carries these securities at fair value, and reports unrealized gains and losses as a separate component of accumulated other comprehensive income (loss). The cost of debt securities is adjusted for amortization of purchase premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income in the statements of operations and comprehensive loss. Realized gains and losses on sales of securities are determined using the specific identification method and recorded in other income, net in the statement of operations and comprehensive loss. We review our portfolio of available-for-sale securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, we recognize a loss in the statement of operations, whereas if the decline in fair value is not due to credit-related factors, we recognize the loss in comprehensive loss. Restricted Cash The Company is required to maintain letters of credit related to its office and lab space leases in South San Francisco. This cash is the collateral for those letters of credit and per the terms of the leases, must remain in place until one to two months after the termination of the leases. As the remaining terms of the leases as of December 31, 2024 is greater than one year, the related restricted cash has been classified as non-current. Property and Equipment, Net Property and equipment, which consist of leasehold improvements, furniture and fixtures, research equipment, computers and software and construction-in-progress are stated at cost less accumulated depreciation. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which ranges from three to five years. Leasehold improvements are amortized over the remaining life of the lease at the time the asset is placed into service. Impairment of Long-Lived Assets The carrying value of long-lived assets, including property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the asset may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. See Note 6 for additional information on the long-lived asset impairment expense recognized for the year ended December 31, 2023. Collaborative Arrangements The Company analyzes its collaboration arrangements to assess whether they are within the scope of Accounting Standards Codification ("ASC") Topic 808, Collaborative Arrangements ("ASC 808"), to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of ASC 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC Topic 606, Revenue from Contracts with Customers ("ASC 606"). If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs consist primarily of salaries and other benefits of research and development personnel, including associated share-based compensation, costs related to research activities, preclinical studies, clinical trial, drug manufacturing and allocated overhead and facility-related expenses. The Company accounts for non-refundable advance payments for goods or services that will be used in future research and development activities as expenses when the goods have been received or when the service has been performed rather than when the payment is made. Clinical trial costs are a component of research and development expenses. The Company expenses costs for its clinical trial activities performed by third parties, including clinical research organizations and other service providers, as they are incurred, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company uses information it receives from internal personnel and outside service providers to estimate the clinical trial costs incurred. Leases At the commencement date of a lease, the Company recognizes lease liabilities which represent its obligation to make lease payments, and right-of-use assets ("ROU assets") which represent its right to use the underlying asset during the lease term. The lease liability is measured at the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at the lease commencement date. The ROU asset is measured at cost, which includes the initial measurement of the lease liability and initial direct costs incurred by the Company and excludes lease incentives. ROU assets are recorded in operating lease ROU assets and lease liabilities are recorded in operating lease liabilities, current and noncurrent in the balance sheets. We have elected the practical expedient to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component for our facilities leases, and elected the short-term lease recognition exemption for our short-term leases, under which we do not recognize lease liabilities and ROU assets for leases with an original term of twelve months or less. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term. The Company does not recognize lease liabilities and ROU assets for short-term leases with terms of twelve months or less. Share-Based Compensation Share-based compensation expense represents the cost of the grant-date fair value of employee, officer, director, and non-employee stock option, employee stock purchase plan, and restricted stock unit grants, estimated in accordance with the applicable accounting guidance, recognized using the straight-line method over the vesting period for service-based options, employee stock purchase plan rights and restricted stock units and using the graded vesting method for performance-based options. The vesting period generally approximates the expected service period of the awards. Forfeitures are recognized and accounted for as they occur. The fair value of stock options and employee stock purchase plan rights are estimated using a Black-Scholes option pricing model on the date of grant. This method requires certain assumptions be used as inputs, such as the fair value of the underlying common stock, expected term of the option before exercise, expected volatility of the Company’s common stock, expected dividend yield, and a risk-free interest rate. Options granted during the year have a maximum contractual term of ten years. The Company has limited historical stock option activity and therefore estimates the expected term of stock options granted using the simplified method, which represents the average of the contractual term of the stock option and its weighted-average vesting period. The expected term of the employee stock purchase plan rights equals the six-month look-back period. The expected volatility is determined by using a blended approach of the Company's historical stock price volatility and the historical stock price volatility for a select group of other publicly traded companies in the same industry. The Company has historically not declared or paid any dividends and does not currently expect to do so in the foreseeable future. The risk-free interest rates used are based on the U.S. Department of Treasury ("U.S. Treasury") yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the stock options. The fair value of restricted stock units is based on the closing price of the Company's common stock as reported on The Nasdaq Global Select Market on the date of grant. Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applicable to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Segment Reporting The Company’s chief operating decision maker ("CODM"), its Chief Executive Officer, manages its operations and business as one operating segment for the purposes of allocating resources, makes operating decisions and evaluates financial performance. No product revenue has been generated since inception and all assets are held in the United States. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares 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 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, unvested restricted stock options, and outstanding stock options under the Company’s equity incentive plans, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive 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. Recent Accounting Pronouncements Adopted 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. The Company adopted this standard in the fiscal year beginning January 1, 2024. There was no impact on the Company’s reportable segments identified and additional required disclosures have been included in Note 13. 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 did not have a material impact on the financial position, results of operations or cash flows of the Company. Accounting Pronouncements Not Yet Adopted 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 November 2024, the FASB issued ASU 2024-03, "Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses". ASU 2024-03 requires public entities to disclose specified information about certain costs and expenses on an interim and annual basis and is effective for annual reporting periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted. The new standard is expected to be applied prospectively, but retrospective application is permitted. The Company is currently evaluating the impact of ASU 2024-03 on the financial statements and related disclosures. 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.

Description of Business

12 Months Ended

Dec. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business

1. 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 autoimmune diseases. 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 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 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 December 31, 2024, the Company had an accumulated deficit of $544.2 million and cash, cash equivalents, restricted cash and short-term and long-term investments of $380.5 million.

Management plans to continue to incur substantial costs 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, 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.

Segment Reporting - Additional Information (Details)	12 Months Ended
Segment Reporting - Additional Information (Details)	Dec. 31, 2024 Segment
Segment Reporting [Abstract]
Number of reportable segments	1
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The Company's measure of segment profit or loss is net loss.

Employee Benefits

12 Months Ended

Dec. 31, 2024

Retirement Benefits [Abstract]

Employee Benefits

9. Employee Benefits

On January 1, 2018, the Company adopted a defined contribution 401(k) plan that is available to eligible employees. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation,

limited to the maximum amount allowable under federal tax regulations. As part of the plan, the Company elected to make non-matching contributions via mandatory 3% of compensation safe harbor nonelective contributions. The Company recognized $0.9 million and $1.0 million for expense related to the nonelective 401(k) contributions for the years ended December 31, 2024 and 2023, respectively.

Share-Based Compensation

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

Share-Based Compensation

11. Share-Based Compensation

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 IPO in July 2020. Upon the effectiveness of the 2020 Plan, no further grants may be made under the Company’s prior equity incentive plan, the 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 December 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). 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 1,868,770 shares was available for new award grants under the 2020 Plan as of December 31, 2024.

The following table summarizes the stock option activity during the year ended December 31, 2024 (in thousands, except number of shares, exercise prices and contractual term):


	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		3,019,050			6.14
Exercised		(144,128	)		4.64
Forfeited		(522,254	)		17.96
Outstanding at December 31, 2024		9,069,194		$	10.55		7.0	$	263
Exercisable at December 31, 2024		4,899,150		$	14.01		6.0	$	108
Vested and expected to vest at December 31, 2024		9,069,194		$	10.55		7.0	$	263

The aggregate intrinsic value represents the difference between the exercise price of stock options and the quoted closing market price of the Company’s common stock on the applicable date for all in-the-money stock options.

Additional information related to the Company’s stock options is summarized below (in thousands, except per share amounts):


	Year Ended December 31,
	2024		2023
Weighted-average grant-date fair value of stock option grants per share	$	5.02	$	3.36
Intrinsic value of options exercised	$	798	$	39

The following table summarizes the restricted stock unit activity during the year ended December 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		798,574			6.04
Forfeited		(59,764	)		6.80
Vested		(165,667	)		8.63
Outstanding at December 31, 2024		1,167,911		$	6.71		1.4

The weighted-average grant-date fair values of restricted stock units granted during the years ended December 31, 2024 and 2023 were $6.04 and $5.57, respectively. The fair value of restricted stock units that vested in the years ended December 31, 2024 and 2023 totaled $1.4 million and $0.4 million, respectively.

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. During 2024 and 2023, 144,049 and 164,567 shares were issued under the ESPP resulting in aggregate cash proceeds of $0.3 million and $0.5 million, respectively. As of December 31, 2024, 1,562,749 shares remained available for issuance under the ESPP (after giving effect to share purchases made under the ESPP through and including the ESPP offering period that ended on November 30, 2024).

Common Stock Reserved for Future Issuance

As of December 31, 2024, the Company had reserved the following shares of common stock for future issuance:


	December 31, 2024
Common stock options and restricted stock units granted and outstanding		10,237,105
Reserved for future equity award grants		1,868,770
Reserved for future ESPP issuances		1,562,749
		13,668,624

Share-Based Compensation Expense

Share-based compensation expense for the years ended December 31, 2024 and 2023 were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Research and development	$	7,955	$	8,025
General and administrative		8,776		9,174
Total share-based compensation expense	$	16,731	$	17,199

The total unrecognized compensation cost related to stock options was $19.4 million, which is expected to be recognized over a weighted-average remaining service period of 2.6 years as of December 31, 2024. The total unrecognized compensation cost related to restricted stock units was $5.6 million, which is expected to be recognized over a weighted-average remaining service period of 2.6 years as of December 31, 2024.

Fair Value Disclosures


	Year Ended December 31,
	2024	2023
Options
Risk-free interest rate	3.5% - 4.5%	3.5% - 4.9%
Expected volatility	100.4% - 117.3%	90.0% - 101.8%
Expected term (in years)	5.5 - 6.1	5.5 - 6.1
Expected dividend yield	—	—
ESPP
Risk-free interest rate	4.4% - 5.4%	4.7% - 5.4%
Expected volatility	83.2% - 152.7%	63.8% - 152.7%
Expected term (in years)	0.5	0.5
Expected dividend yield	—	—

The Company recognizes compensation costs related to stock options granted to employees and nonemployees based on the estimated fair value of the awards on the date of grant, net of forfeitures. The Company generally recognizes grant-date fair value of stock options granted to employees and non-employee service providers on a straight-line basis over the requisite service period, which is generally the vesting term of the respective awards. The Company determines the fair value of stock options with a service and performance condition, or performance-based options as described above. The Company accounts for the impact of forfeitures as they occur. The determination of the fair value of share-based payment awards utilizing the Black-Scholes option-pricing model is affected by the Company’s stock price and a number of assumptions, including expected volatility, expected life, risk-free interest rate and expected dividends.

Expected term. The Company opted to use the “simplified method” for estimating the expected term of employee options, whereby the expected term equals the average of the vesting term and the original contractual term of the option (generally 10 years). The expected term of the employee stock purchase plan rights equals the six-month look-back period.

Expected volatility. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, since inception and prior to 2023, the Company based its estimate of expected volatility on an average of the historical volatilities of the common stock of comparable publicly traded biopharmaceutical companies over a period equal to the expected term of the stock option grants. For the grants during 2023 and 2024, the expected volatility was determined by using a blended approach of the Company’s historical stock price volatility and the historical stock price volatility for a select group of other publicly traded companies in the same industry. The comparable companies were chosen based on their similar size, stage in the life cycle, and financial leverage to the Company.

Risk-free interest rate. The risk-free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of the stock options.

Expected dividend yield. The Company has not issued any dividends and does not expect to issue dividends over the life of the options, as a result the estimated dividend yield is zero.

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (108,790)	$ (117,501)

- Definition

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

+ References

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+ Details

Income Taxes - Significant Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carry forwards	$ 53,520	$ 43,491
Depreciation and amortization	338	334
Research and development credits	25,123	19,782
Share-based compensation	5,122	4,668
Accrued expenses	1,535	1,402
Lease liability	16,857	18,551
Other, net	62	49
Section 174 Capitalized R&D	39,385	30,147
Total deferred tax assets	141,942	118,424
Valuation allowance for deferred tax assets	(127,479)	(102,169)
Deferred tax assets, net of valuation allowance	14,463	16,255
Deferred tax liabilities:
ROU asset	(7,644)	(8,404)
Depreciation and amortization	(6,819)	(7,851)
Net deferred tax assets	$ 0	$ 0

Statements of Cash Flows - USD ($)	12 Months Ended
Statements of Cash Flows - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net loss	$ (108,790,000)	$ (117,501,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	16,731,000	17,199,000
Depreciation and amortization expense	9,152,000	5,869,000
Accretion of discount and amortization of premium on investments, net	(6,912,000)	(8,940,000)
Non-cash lease expense	2,286,000	2,222,000
Realized gain on investments		(34,000)
Impairment of right-of-use assets	0	4,100,000
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,365,000)	1,716,000
Operating lease liabilities	(6,416,000)	4,986,000
Accounts payable and accrued and other liabilities	(4,469,000)	4,223,000
Other long-term liabilities	87,000
Net cash used in operating activities	(99,696,000)	(86,160,000)
Cash flows from investing activities:
Purchases of investments	(406,376,000)	(260,233,000)
Proceeds from sales and maturities of investments	281,230,000	367,395,000
Purchases of property and equipment	(4,409,000)	(28,147,000)
Net cash (used in) provided by investing activities	(129,555,000)	79,015,000
Cash flows from financing activities:
Proceeds from issuance of common stock and pre-funded warrants, net of issuance costs	225,073,000
Proceeds from ESPP purchases	343,000	530,000
Proceeds from stock option exercises	668,000	161,000
Net cash provided by financing activities	226,084,000	691,000
Net decrease in cash and cash equivalents	(3,167,000)	(6,454,000)
Cash, cash equivalents and restricted cash at beginning of year	33,783,000	40,237,000
Cash, cash equivalents and restricted cash at end of year	30,616,000	33,783,000
Reconciliation of cash, cash equivalents and restricted cash to the balance sheets:
Cash and cash equivalents	27,873,000	31,040,000
Restricted cash	2,743,000	2,743,000
Total cash, cash equivalents and restricted cash	30,616,000	33,783,000
Supplemental disclosures of non-cash investing activities:
Acquisitions of property and equipment recorded in accounts payable and accrued and other current liabilities	343,000	268,000
Right-of-use assets obtained in exchange for operating lease liabilities resulting from modified leases	579,000	$ 431,000
Decrease in right-of-use asset and lease liability due to termination	$ 2,229,000

Description of Business - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($) Segment	Dec. 31, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments \| Segment	1
Accumulated deficit	$ 544,224	$ 435,434
Cash, cash equivalents restricted cash and short-term and long-term investments	$ 380,500

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Summary of Reconciliation to Net Loss

A reconciliation to the net loss for the years ended December 31, 2024 and 2023 is included at the bottom of the table below.


	December 31,
	2024			2023
Segment expenses:
Personnel related expenses, excluding share-based compensation	$	41,129		$	42,329
Facilities expenses		19,403			16,392
Direct external development program expenses		21,431			29,517
Other segment expenses (1)		20,348			16,244
Total segment expenses:		102,311			104,482
Segment loss		(102,311	)		(104,482	)

Reconciling items:
Depreciation and amortization		(9,152	)		(5,869	)
Share-based compensation		(16,731	)		(17,199	)
Impairment of ROU asset					(4,100	)
Interest income		19,317			14,107
Other income, net		87			42
Net loss	$	(108,790	)	$	(117,501	)

(1) Other segment items include consultants and contractor, lab supplies, and general business expenses.

Collaboration and License Agreements

12 Months Ended

Dec. 31, 2024

Collaboration Agreement [Abstract]

Collaboration and License Agreements

8. Collaboration and License Agreements

CRISPR Collaboration Agreement

On May 5, 2021, the Company entered into the CRISPR Agreement with CRISPR to co-develop and co-commercialize an allogeneic, off-the-shelf CAR NK product candidate targeting the CD70 tumor antigen and an allogeneic, off-the-shelf product candidate that comprises both engineered NK cells and engineered T cells. The agreement has been amended over the years to revise the transfer of materials, nomination provisions, 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 five CRISPR-Cas9 gene editing targets 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. The related impact of the cost sharing activities are included in research and development expense on the statements of operations and comprehensive loss. Expenses related to services performed by the Company are classified as research and development expenses. Payments received from CRISPR for partial reimbursement of expenses are recorded as a reduction of research and development expenses. Reduction of research and development expense resulting from partial reimbursement from CRISPR was $0.1 million and $1.6 million for the years ended December 31, 2024 and 2023, respectively. As of December 31, 2024 and 2023, the Company had an immaterial and $0.2 million receivable, respectively, under the research cost sharing provision, which is included as part of prepaid expenses and other current assets in the balance sheet. The Company has deprioritized further development of NKX070 and NK+T.

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 December 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 or are probable.

MaxCyte License Agreement

On October 26, 2021, the Company entered into a license agreement (the "MaxCyte Agreement") with MaxCyte, Inc. ("MaxCyte") to obtain non-exclusive clinical and commercial rights to use MaxCyte's cell loading technology to develop and commercialize in up to ten licensed products.

In connection with the MaxCyte Agreement, the Company must pay to MaxCyte annual research license fees and commercialization license fees, ranging from $0.1 million to $0.3 million, for each instrument licensed by the Company. Further, the Company could be required to make milestone payments to MaxCyte upon completion of certain regulatory and commercial milestones related to the clinical development and commercialization of certain of the Company’s licensed products. The aggregate potential milestone payments range from $10 million to $13 million per licensed product. Additionally, the Company may be required to make net sales milestone payments totaling between $61.9 million to $116.8 million per licensed product. As of December 31, 2024, no milestones have been achieved.

University of Singapore and St. Jude Children’s License Agreement

In August 2016, the National University of Singapore ("NUS") and St. Jude Children’s Research Hospital ("St. Jude") and the Company entered into a license agreement under which NUS and St. Jude (the "Licensors") granted the Company an exclusive, royalty-bearing, worldwide license to its patent rights related to a method for expanding natural killer cells; a chimeric receptor with NKG2D specificity; and a method for supporting autonomous natural killer cell function ("NUS and St. Jude License Agreement"). The NUS and St. Jude License Agreement provides the Company with the rights to grant and authorize sublicenses to make, have made, use, sell, offer for sale and import products and otherwise exploit the patent rights.

As consideration for the license, the Company made an upfront payment of $31,800 and issued NUS 250,000 shares of the Company’s common stock. The Company determined that the upfront payment (SGD 42,750) and value of the common stock issued ($2,500 based on fair value at time of issuance) as part of the license agreement would be expensed upon execution of the contract as the license was acquired for research and development purposes which does not have alternative future uses, and the underlying technology has not reached technological feasibility, hence the Company expensed these costs during 2016.

In addition, the Company is required to pay an annual license maintenance fee of SGD 25,000, increasing to SGD 50,000 after year two of the agreement. Further, the Company could be required to make milestone payments to the Licensors upon completion of certain regulatory and commercial milestones related to the clinical development and commercialization of certain of the Company’s product candidates. The aggregate potential milestone payments are approximately SGD 5 million. The Company has also agreed to pay the Licensors royalties of 2.5% of net sales of products sold by the Company or through a sublicense. Additionally, the Company agreed to pay the Licensors a tiered percentage of sublicensing income (ranging from 7.5% to 20%) based on the timing of capital raised and stage of clinical trials. The NUS and St. Jude License Agreement also includes certain performance objectives which obligate the Company to meet various milestones related to the clinical development and commercialization of certain of the Company’s product candidates over time for up to 120 months after the effective date of the NUS and St. Jude License Agreement.

The Company recorded $37,000 license maintenance fees included as part of research and development expenses for each of the years ended December 31, 2024 and 2023. As of December 31, 2024, no milestones have been achieved.

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2019	Dec. 31, 2022
Income Taxes [Line Items]
Provision or benefit for income taxes	$ 0	$ 0
Increase in valuation allowance of net deferred tax assets	25,300,000	30,600,000
Gross unrecognized tax benefits	4,748,000	3,738,000		$ 2,339,000
Unrecognized tax benefits, penalties and interest expense	0	$ 0
Net Operating Loss and Tax Credit Carryforwards to Offset \| Minimum
Income Taxes [Line Items]
Changes in ownership by stockholders holding percentage			5.00%
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	233,200,000
Federal \| Research and Development Credit Carry Forwards
Income Taxes [Line Items]
Tax credit carryforwards	$ 22,000,000
Tax credit carryforwards, expire	2035
Federal \| 2035
Income Taxes [Line Items]
Net operating loss carryforwards	$ 3,200,000
Net operating loss carryforwards, expire	2035
Federal \| Carry Forward Indefinitely
Income Taxes [Line Items]
Net operating loss carryforwards	$ 230,000,000
California State
Income Taxes [Line Items]
Net operating loss carryforwards, expire	2036
California State \| Research and Development Credit Carry Forwards
Income Taxes [Line Items]
Tax credit carryforwards	$ 9,500,000
California State \| Carry Forward Indefinitely
Income Taxes [Line Items]
Net operating loss carryforwards	$ 65,100,000

Share-Based Compensation - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 16,731	$ 17,199
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	7,955	8,025
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 8,776	$ 9,174

Segment Reporting

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Segment Reporting

13. Segment Reporting

The Company operates as a single reporting segment, focused on the research and development of cell therapies for patients with autoimmune diseases. The Company's measure of segment profit or loss is net loss. The Chief Executive Officer, as the CODM, manages and allocates resources to the operations of the Company on a total company basis. The Company monitors its cash, cash equivalents, and investments as reported on the Company's Balance Sheets to determine funding for its research and development.

As the Company is not yet generating revenue, the CODM evaluates its performance based on progress in pre-clinical and clinical research objectives. Along with the Company’s Statement of Operations and Comprehensive Loss, the CODM regularly reviews budgeted and forecasted expenses to assess liquidity requirements and allocate cash accordingly.

The following table is representative of the significant expense categories regularly provided to the CODM when managing the Company's single reporting segment.

A reconciliation to the net loss for the years ended December 31, 2024 and 2023 is included at the bottom of the table below.


	December 31,
	2024			2023
Segment expenses:
Personnel related expenses, excluding share-based compensation	$	41,129		$	42,329
Facilities expenses		19,403			16,392
Direct external development program expenses		21,431			29,517
Other segment expenses (1)		20,348			16,244
Total segment expenses:		102,311			104,482
Segment loss		(102,311	)		(104,482	)

Reconciling items:
Depreciation and amortization		(9,152	)		(5,869	)
Share-based compensation		(16,731	)		(17,199	)
Impairment of ROU asset					(4,100	)
Interest income		19,317			14,107
Other income, net		87			42
Net loss	$	(108,790	)	$	(117,501	)

(1) Other segment items include consultants and contractor, lab supplies, and general business expenses.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 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 \| Maximum
Loss Contingencies [Line Items]
Letter of credit notice period by financial institution before annual expiration date	60 days
Agreement with Financial Institution \| Minimum
Loss Contingencies [Line Items]
Letter of credit notice period by financial institution before annual expiration date	30 days

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2024
Trading Arrangements, by Individual
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

Commitments and Contingencies

12 Months Ended

Dec. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments and 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 December 31, 2024 and 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 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.

Segment Reporting - Summary of Reconciliation to Net Loss (Details) - USD ($)

12 Months Ended

Dec. 31, 2024

Dec. 31, 2023

Segment expenses:

Total operating expenses

$ 128,194,000

$ 131,650,000

Net loss

(108,790,000)

(117,501,000)

Reconciling items:

Depreciation and amortization

(9,152,000)

(5,869,000)

Share-based compensation

(16,731,000)

(17,199,000)

Impairment of ROU asset

(4,100,000)

Interest income

19,317,000

14,107,000

Other income, net

87,000

42,000

Segment

Segment expenses:

41,129,000

42,329,000

Facilities expenses

19,403,000

16,392,000

Direct external development program expenses

21,431,000

29,517,000

Other segment expenses

^[1]

20,348,000

16,244,000

Total operating expenses

102,311,000

104,482,000

Net loss

$ (102,311,000)

$ (104,482,000)

[1]	Other segment items include consultants and contractor, lab supplies, and general business expenses.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Reconciliation on Income Taxes Amount Computed by Applying Statutory Federal Income Tax Rate to Net Loss

A reconciliation on income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows (in thousands):


	Year Ended December 31,
	2024			2023
Income tax benefit at statutory rates	$	(22,846	)	$	(24,675	)
State income tax, net of federal benefit		(1,701	)		(1,438	)
Permanent items		2,877			1,656
Research and development credits		(3,640	)		(6,170	)
Change in valuation allowance		25,310			30,627
Income tax expense	$	—		$	—

Significant Components of Deferred Tax Assets

Significant components of the Company’s deferred tax assets are shown below (in thousands):


	December 31,
	2024			2023
Deferred tax assets:
Net operating loss carry forwards	$	53,520		$	43,491
Depreciation and amortization		338			334
Research and development credits		25,123			19,782
Share-based compensation		5,122			4,668
Accrued expenses		1,535			1,402
Lease liability		16,857			18,551
Other, net		62			49
Section 174 Capitalized R&D		39,385			30,147
Total deferred tax assets		141,942			118,424
Valuation allowance for deferred tax assets		(127,479	)		(102,169	)
Deferred tax assets, net of valuation allowance		14,463			16,255
Deferred tax liabilities:
ROU asset		(7,644	)		(8,404	)
Depreciation and amortization		(6,819	)		(7,851	)
Net deferred tax assets	$	—		$	—

Summary of Changes in Gross Unrecognized Tax Benefits

The following table summarizes the changes in the Company’s gross unrecognized tax benefits (in thousands):


	December 31,
	2024			2023
Balance at the beginning of the year	$	3,738		$	2,339
Increases (decreases) related to tax positions taken in prior years		(83	)		102
Increases related to tax positions taken in current year		1,093			1,297
Balance at the end of the year	$	4,748		$	3,738