Tenaya Therapeutics (TNYA) 10-K 18 Mar 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Mar. 01, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Trading Symbol	TNYA
Entity Registrant Name	TENAYA THERAPEUTICS, INC.
Entity Central Index Key	0001858848
Entity File Number	001-40656
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Entity Tax Identification Number	81-3789973
Entity Address, Address Line One	171 Oyster Point Boulevard
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	825-6990
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
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	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Public Float			$ 271.5
Entity Common Stock, Shares Outstanding		78,516,142
Documents Incorporated by Reference	Portions of the definitive proxy statement for the Registrant’s 2023 Annual Meeting of Stockholders are incorporated by reference in Part III of this Form 10-K. Such definitive proxy statement will be filed with the Securities and Exchange Commission within 120 days after the end of the Registrant’s 2023 fiscal year ended December 31, 2023.
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	San Francisco, California

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 45,681	$ 95,272
Short-term investments in marketable securities	58,961	91,255
Prepaid expenses and other current assets	6,940	7,227
Total current assets	111,582	193,754
Property and equipment, net	43,277	51,032
Operating lease right-of-use assets	9,979	11,663
Long-term investments in marketable securities		17,703
Other noncurrent assets	5,677	4,793
Total assets	170,515	278,945
Current liabilities:
Accounts payable	5,630	9,578
Accrued and other current liabilities	12,784	10,664
Operating lease liabilities, current	4,319	4,006
Total current liabilities	22,733	24,248
Operating lease liabilities, noncurrent	8,105	11,093
Other noncurrent liabilities	253	228
Total liabilities	31,091	35,569
Commitments and contingencies (Note 5)
Stockholders' equity:
Preferred stock, $0.0001 par value; 200,000,000 shares authorized as of December 31, 2023 and 2022; no shares issued and outstanding as of December 31, 2023 and 2022
Common stock, $0.0001 par value; 1,000,000,000 shares authorized as of December 31, 2023 and 2022; 68,330,342 and 66,857,113 shares issued and outstanding as of December 31, 2023 and 2022	7	7
Additional paid-in capital	542,805	522,945
Accumulated other comprehensive loss	(106)	(378)
Accumulated deficit	(403,282)	(279,198)
Total stockholders' equity	139,424	243,376
Total liabilities and stockholders' equity	$ 170,515	$ 278,945

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, authorized	200,000,000	200,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized	1,000,000,000	1,000,000,000
Common stock, issued	68,330,342	66,857,113
Common stock, outstanding	68,330,342	66,857,113

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 98,038	$ 94,537
General and administrative	33,155	31,084
Total operating expenses	131,193	125,621
Loss from operations	(131,193)	(125,621)
Other income, net:
Interest income	7,056	1,954
Other income, net	53	2
Total other income, net	7,109	1,956
Net loss before income tax expense	(124,084)	(123,665)
Net loss	(124,084)	(123,665)
Other comprehensive income (loss):
Net unrealized gain (loss) on marketable securities	272	(237)
Comprehensive loss	$ (123,812)	$ (123,902)
Net loss per share, basic	$ (1.68)	$ (2.76)
Net loss per share, diluted	$ (1.68)	$ (2.76)
Weighted-average shares used in computing net loss per share, basic	73,786,126	44,823,597
Weighted-average shares used in computing net loss per share, diluted	73,786,126	44,823,597

Statements of Stockholders' Equ

Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	At The Market Sales	Common Stock	Common Stock At The Market Sales	Additional Paid-In Capital	Additional Paid-In Capital At The Market Sales	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2021	$ 278,526		$ 4		$ 434,196		$ (141)	$ (155,533)
Balance, shares at Dec. 31, 2021			41,291,374
Issuance of common stock and pre-funded warrants, net of issuance costs	76,886		$ 3		76,883
Issuance of common stock and pre-funded warrants, net of issuance costs, shares			25,429,716
Issuance of common stock upon exercise of stock options and vesting of restricted stock units	51				51
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares			32,609
Issuance of common stock pursuant to employee stock purchase plan	329				329
Issuance of common stock pursuant to employee stock purchase plan, shares			106,192
Repurchase of common stock related to early exercise of options, shares			(2,778)
Vesting of early exercised stock options	19				19
Stock-based compensation	11,467				11,467
Other comprehensive loss	(237)						(237)
Net loss	(123,665)							(123,665)
Balance at Dec. 31, 2022	243,376		$ 7		522,945		(378)	(279,198)
Balance, shares at Dec. 31, 2022			66,857,113
Conversion of convertible preferred stock to common stock upon completion of initial public offering, shares			302,517
Issuance of common stock in connection with at-the-market sales, net of issuance costs		$ 3,868				$ 3,868
Issuance of common stock in connection with at-the-market sales, net of issuance costs, shares				535,767
Issuance of common stock upon exercise of stock options and vesting of restricted stock units	29				29
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares			265,047
Issuance of common stock pursuant to employee stock purchase plan	653				653
Issuance of common stock pursuant to employee stock purchase plan, shares			369,898
Vesting of early exercised stock options	1				1
Stock-based compensation	15,309				15,309
Other comprehensive loss	272						272
Net loss	(124,084)							(124,084)
Balance at Dec. 31, 2023	$ 139,424		$ 7		$ 542,805		$ (106)	$ (403,282)
Balance, shares at Dec. 31, 2023			68,330,342

Statements of Stockholders' E_2

Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Stock issuance costs	$ 501
Follow-On Offering
Stock issuance costs		$ 5,441
Feb 2024 Follow-On Offering
Stock issuance costs	$ 120

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (124,084)	$ (123,665)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8,687	6,467
Amortization (accretion) of premium (discount) on marketable securities	315	(307)
Stock-based compensation	15,309	11,467
Non-cash operating lease expense	3,132	2,246
Other	217	217
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	101	(2,934)
Other noncurrent assets	(601)	(815)
Accounts payable	(3,282)	1,660
Accrued and other current liabilities	2,256	4,348
Operating lease liabilities	(4,123)	(3,107)
Other noncurrent liabilities	1	(1)
Net cash used in operating activities	(102,072)	(104,424)
Cash flows from investing activities:
Purchases of property and equipment	(1,239)	(20,630)
Purchases of marketable securities	(56,644)	(140,476)
Proceeds from maturities of marketable securities	106,623	244,750
Other	(25)	8
Net cash provided by investing activities	48,715	83,652
Cash flows from financing activities:
Proceeds from issuance of common stock and pre-funded warrants in follow-on offering, net of issuance costs		77,387
Proceeds from at-the-market sales, net of issuance costs	3,868
Payment of accrued offering costs	(501)
Proceeds from exercise of stock options and employee stock purchase plan	682	380
Net cash provided by financing activities	4,049	77,767
Net change in cash, cash equivalents and restricted cash	(49,308)	56,995
Cash and cash equivalents and restricted cash at beginning of period	95,671	38,676
Cash and cash equivalents and restricted cash at end of period	46,363	95,671
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	45,681	95,272
Restricted cash included in other noncurrent assets	682	399
Cash, cash equivalents and restricted cash	46,363	95,671
Supplemental disclosure of non-cash investing and financing activities:
Offering costs related to November 2022 public offering included in accounts payable and accrued and other current liabilities		501
Property and equipment included in accounts payable and accrued and other current liabilities	$ 249	$ 549

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (124,084)	$ (123,665)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
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

Organization and Description of

Organization and Description of the Business	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	Note 1. Organization and Description of the Business Description of the Business Tenaya Therapeutics, Inc. (the Company) was incorporated in the state of Delaware in August 2016 and is headquartered in South San Francisco, California. The Company is a clinical-stage biotechnology company focused on discovering, developing and delivering curative therapies that address the underlying drivers of heart disease. The Company’s lead product candidates include, TN-201, a gene therapy for myosin binding protein C3-associated hypertrophic cardiomyopathy, TN-401, a gene therapy for plakophilin 2-associated arrhythmogenic right ventricular cardiomyopathy and TN-301, a small molecule for heart failure with preserved ejection fraction. Liquidity The Company has incurred net losses since inception and expects such losses to continue in the future as it conducts research and development activities. As of December 31, 2023, the Company had an accumulated deficit of $ 403.3 million. The Company incurred a net loss of $ 124.1 million and $ 123.7 million during the years ended December 31, 2023 and 2022, respectively. The Company had $ 104.6 million of cash, cash equivalents and investments in marketable securities as of December 31, 2023. Management recognizes the need to raise additional capital to fully implement its business plan. The Company may seek to raise capital through equity financings, debt financings, license agreements, strategic collaborations or other sources of financing. On February 12, 2024, the Company completed an underwritten offering and received net proceeds of $ 46.5 million. See Note 10 to the Company's financial statements for details. Management believes its existing cash, cash equivalents and investments in marketable securities as of December 31, 2023, along with the additional $ 46.5 million mentioned above, will be sufficient to fund the Company’s operations for at least the next twelve months following the date these financial statements are filed with the Securities and Exchange Commission (SEC).

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to, the valuation of equity-based awards and accrued expenses related to research and development activities. The Company bases its estimates on historical experience, the current economic environment, and on various other assumptions that are believed to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: Level 1 - Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 - Inputs other than quoted market prices included in Level 1 are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 - Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short-term nature. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentration of risk consist principally of cash, cash equivalents and marketable securities. The Company maintains deposits in cash and cash equivalents in federally insured financial institutions that it believes have high credit quality. Such deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and the issuers of its investments in marketable securities to the extent recorded in the balance sheets. The Company has not experienced any losses on its deposits of cash and cash equivalents. Risks and Uncertainties The Company is subject to certain risks including, but not limited to, the ability to obtain future financing, possible failure of ongoing and future clinical trials, the need to obtain regulatory approvals for its product candidates, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, competitive developments, protection of proprietary technology, the ability to make milestone, royalty or other payments due under licensing agreements, and the Company’s ability to attract and retain employees necessary to support its business plan. Segment Information The Company views its operations and manages its business as one operating segment , which is the business of discovering and developing potential treatments that address the underlying drivers of heart disease. The Company’s long-lived assets are located in the United States. Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents primarily consist of money market funds that are stated at fair value. Restricted Cash The restricted cash primarily represents security deposits for the Company’s operating leases in South San Francisco, and Union City, California. The security deposits are in the form of a letter of credit secured by restricted cash. Marketable Securities The Company invests in marketable securities, primarily securities issued by the U.S. government and its agencies, commercial paper and corporate bonds. All marketable securities have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company evaluates securities for impairment at the end of each reporting period. Factors considered in the evaluation include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospect of the issuer, and the Company’s intent and ability to hold the investment to allow for anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit-related is reported as a component of other comprehensive loss. Realized gains and losses are included in other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest earned on marketable securities is included in interest income. Property and Equipment, Net Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years . Leasehold improvements are amortized over the shorter of the assets’ expected lives or the remaining lease term. Costs for capital assets not yet placed into service are capitalized as construction in progress and are not depreciated until the asset is placed in service. Upon retirement or sale, the cost of disposed assets and their related accumulated depreciation are removed from the balance sheets. Any resulting gains or losses on dispositions of property and equipment are included as a component of other income (expense), net, within the Company’s statements of operations and comprehensive loss. Repair and maintenance costs, which are not considered improvements and do not extend the useful life of property and equipment, are expensed as incurred. Impairment for Long-Lived Assets Long-lived assets, including construction in progress, are reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by comparing the carrying amount of an asset to the estimated undiscounted future net cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There was no impairment of long-lived assets for any of the periods presented. Leases The Company determines if an arrangement is a lease at inception. Operating lease right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term at the commencement date of the lease. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less any lease incentive received. The Company uses the rate implicit in the lease in determining the present value of lease payments and, if that rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at the date of lease commencement. The incremental borrowing rate reflects the rate of interest that a lessee would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company’s non-lease components are primarily related to property taxes, insurance, and common area maintenance, which vary based on future outcomes, and are recognized as rent expense when incurred. Research and Development Expenses Research and development (R&D) costs are expensed as incurred. Research and development expenses include, among others, consulting fees, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocated facilities and overhead costs, fees related to licensing agreements, fees paid to contract research organizations (CRO) that conduct research and development activities on the Company’s behalf and costs related to compliance with regulatory requirements. Goods or services incurred for research and development activities that have not yet been invoiced are recorded as liabilities within accrued expenses and other current liabilities on the Company’s balance sheets. The Company has and may continue to acquire the rights to licensed technology that represents in-process research and development to use and develop in the commercialization of new product candidates. The upfront payments made to acquire licenses, product or rights, or payments made related to future milestone payments are recognized as research and development expenses provided that there is no alternative future use of the rights in other research and development projects, up to the point of regulatory approval. Milestone payments are expensed when the specific milestone has been achieved. Non-refundable advance payments for goods or services to be rendered as part of future research and development activities are capitalized on the Company’s balance sheets until the goods or services are received. Classification between prepaid expenses and other current assets and other non-current assets is based on an evaluation of when the goods will be delivered and/or services will be performed, with such amounts subsequently amortized to expense once incurred. Stock-Based Compensation The Company measures and records expense related to all equity awards granted to employees and non-employees in the statements of operations and comprehensive loss based on their grant date fair values, including stock options and restricted stock awards. For stock-based awards that vest subject to the satisfaction of a service requirement, the expense is recognized using the straight-line method over the requisite service period, which is generally the vesting period. Forfeitures are recognized as they occur. The fair value of restricted stock awards is determined on the date of grant based on the estimated fair value of the Company’s common stock on that date. For purposes of determining the estimated fair value of options granted to employees and nonemployees, the Company uses the Black-Scholes option pricing model. See Note 7 to the Company's financial statements for the specific assumptions used in applying the Black-Scholes valuation model. Income Taxes The Company accounts for income taxes using the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded for deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. As of December 31, 2023 and 2022, the Company has recorded a full valuation allowance on its net deferred tax assets. Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties, if any, related to unrecognized tax benefits are included within the provision for income tax. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of the Company’s common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Basic shares of common stock outstanding include the weighted-average effect of the Company’s pre-funded warrants issued in November 2022 because the pre-funded warrants have a nominal exercise price. As the Company is in a loss position for the periods presented, diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive. Shares related to early exercised stock options that are subject to repurchase are excluded from the basic and diluted net loss per share calculation until the Company’s repurchase right lapses. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (a) is no longer an emerging growth company or (b) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which replaces the existing incurred loss impairment model with an expected credit loss model. This standard requires companies to recognize an allowance for credit losses on available-for-sale debt securities rather than the prior approach of recording a reduction to the carrying value of the asset. ASU 2016-13 became effective for the Company beginning January 1, 2023 . The adoption of this standard did no t have a material impact on the Company's financial statements. Recently Issued Accounting Pronouncements Note Yet Adopted In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for the Company beginning January 1, 2025. The Company is evaluating the impact of this standard on its financial statements and related disclosures. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (ASU 2023-07), which improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. In addition, ASU 2023-07 enhances interim disclosure requirements, clarifies circumstances in which an entity can disclose multiple segment measures of profit or loss, provided new segment disclosure requirements for entities with a single reportable segment, and contains other disclosure requirements. ASU 2023-07 is effective for the Company beginning January 1, 2024. The Company is evaluating the impact of this standard on its financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 3. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: Level 1 - Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 - Inputs other than quoted market prices included in Level 1 are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 - Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. The following tables summarize the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy: December 31, 2023 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Money market funds Level 1 91 — — 91 U.S. treasuries Level 1 3,595 — — 3,595 Commercial paper Level 2 34,901 — ( 18 ) 34,883 Government agencies bonds Level 2 6,389 1 — 6,390 Marketable securities: U.S. treasuries Level 1 16,182 4 ( 15 ) 16,171 Commercial paper Level 2 2,971 — ( 2 ) 2,969 Government agencies bonds Level 2 39,897 6 ( 82 ) 39,821 Total financial assets $ 104,026 $ 11 $ ( 117 ) $ 103,920 December 31, 2022 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Cash equivalents Level 1 $ 20,532 $ — $ — $ 20,532 Money market funds Level 1 7,203 — — 7,203 Commercial paper Level 2 11,972 — ( 4 ) 11,968 Government agencies bonds Level 2 54,569 12 — 54,581 Marketable securities: U.S. treasuries Level 1 25,273 1 ( 147 ) 25,127 Commercial paper Level 2 43,605 4 ( 125 ) 43,484 Corporate bonds Level 2 2,696 — ( 18 ) 2,678 Government agencies bonds Level 2 37,770 9 ( 110 ) 37,669 Total financial assets $ 203,620 $ 26 $ ( 404 ) $ 203,242 Money market funds and U.S. treasury securities are classified as Level 1 because they are valued using quoted market prices in active markets for identical assets. Financial instruments classified within Level 2 of the fair value hierarchy are valued based on observable inputs or can be derived from non-binding quotes from the Company’s investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments, or historical pricing trends of a security relative to its peers. The Company believes it is more likely than not that its marketable securities in an unrealized loss position will be held until maturity or the recovery of the cost basis of the investment. As of December 31, 2023, the Company has no t recorded any allowance for credit losses on its investment securities. Based upon its quarterly impairment review, the Company determined that the unrealized losses were not attributed to credit risk, but were primarily driven by the broader change in interest rates. As of December 31, 2023, all available-for-sale marketable securities had remaining maturities of less than one year . The carrying amount of the Company’ s remaining financial assets and liabilities, which include cash, receivables and payables, approximate their fair values due to their short-term nature.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Note 4. Balance Sheet Components Property and Equipment, Net Property and equipment, net, consists of the following: December 31, December 31, (In thousands) Leasehold improvements $ 25,608 $ 23,605 Laboratory equipment 19,973 20,537 Manufacturing equipment 17,716 17,468 Construction in progress 1,730 3,128 Computer equipment and software 1,614 1,060 Furniture and fixtures 976 910 Total property and equipment $ 67,617 $ 66,708 Less: accumulated depreciation and amortization ( 24,340 ) ( 15,676 ) Total property and equipment, net $ 43,277 $ 51,032 Depreciation and amortization expense for the years ended December 31, 2023 and 2022, was $ 8.7 million and $ 6.5 million, respectively. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: December 31, December 31, (In thousands) Accrued compensation and related expenses $ 8,700 $ 6,299 Accrued research and development expenses 2,583 3,214 Accrued professional services 743 482 ESPP deduction liability 88 124 Accrued facility management services 185 — Other current liabilities 485 545 Total accrued and other current liabilities $ 12,784 $ 10,664 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: December 31, December 31, (In thousands) Prepaid expenses 5,783 4,044 Tax credit receivable — 2,245 Other current assets 1,157 938 Total prepaid expenses and other current assets $ 6,940 $ 7,227

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 5. Commitments and Contingencies Facility Leases In December 2016, the Company entered into a lease agreement for office and laboratory space in South San Francisco, California. The lease expires in May 2025 and the Company may renew the lease term for two additional five-year periods. In February 2021, the Company entered into a lease agreement for the Union City Facility. The lease commenced in May 2021 and has a ten-year term with one five-year renewal option. In November 2021, the Company entered into a short-term sublease agreement for additional office and laboratory space in South San Francisco, California with a lease term that was initially set to expire on June 30, 2022 . In May 2022, the Company entered into an amendment to extend the term for the existing sublease premise through December 31, 2022 . Under the amendment, the Company also subleased additional office and laboratory space at the same sublease premise through November 30, 2023. In October 2023, the Company entered into a second amendment for additional laboratory space and to extend the term of the sublease premise through November 30, 2024 . Information related to operating lease activity during the year ended December 31, 2023 was as follows (in thousands): Year Ended December 31, 2023 2022 Operating lease cost $ 4,356 $ 3,714 Variable lease cost 1,265 1,209 Short-term lease cost 5 952 Total lease cost $ 5,626 $ 5,875 Operating lease right-of-use assets obtained in exchange for lease obligations $ 1,448 $ 2,224 Cash paid for amounts included in the measurement of lease liabilities $ 5,347 $ 4,293 As of December 31, 2023, the Company’ s operating leases had a weighted average remaining lease term of 5.1 years and a weighted average discount rate of 9.3 %. Future minimum lease payments under the Company’s operating leases as of December 31, 2023 were as follows: Amount (In thousands) 2024 $ 5,277 2025 2,445 2026 1,386 2027 1,428 2028 1,471 Thereafter 4,006 Total undiscounted future minimum lease payments $ 16,013 Imputed interest ( 3,589 ) Total operating lease liabilities $ 12,424 Purchase Commitments The Company enters into contractual agreements with various suppliers in the normal course of its business, including vendors that provide machinery and equipment. All contracts are terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, the Company would only be obligated for the products or services that the Company had received through the time of termination. Indemnification From time to time, the Company may become involved in litigation and other legal actions. The Company estimates the range of liability related to any pending litigation where the amount and range of loss can be estimated. The Company records its best estimate of a loss when the loss is considered probable. Where a liability is probable and there is a range of estimated loss with no best estimate in the range, the Company records a charge equal to at least the minimum estimated liability for a loss contingency when both of the following conditions are met: (i) information available prior to issuance of the financial statements indicates that it is probable that a liability had been incurred at the date of the financial statements and (ii) the range of loss can be reasonably estimated. The Company was not involved in any material litigation as of December 31, 2023 and 2022. In the normal course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amounts of future payments the Company could be required to make under these provisions is not determinable. In addition, the Company has entered into indemnification agreements with its directors and certain officers that may require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. As of December 31, 2023 and 2022, the Company did not have any material indemnification claims that were probable or reasonably possible and, consequently, has not recorded any related liabilities.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Stockholders' Equity	Note 6. Stockholders ’ Equity Common Stock The holders of common stock are entitled to one vote per share on all matters to be voted on by the stockholders of the Company and are entitled to dividends, if and when declared by the board of directors, subject to the prior rights of the preferred stockholders. Common stock issued and outstanding on the balance sheets and statements of stockholders’ equity includes shares related to early exercised options and restricted stock that are subject to repurchase. Common stock issued and outstanding is reduced for any repurchases of early exercised stock options and restricted stock. “At-the-Market” Equity Offering On August 10, 2022, the Company entered into a sales agreement (Sales Agreement) with Leerink Partners LLC (formerly SVB Securities LLC) to establish an at-the-market (ATM) offering defined in Rule 415 under the Securities Act. Pursuant to the Sales Agreement, the Company is permitted to offer and sell, from time to time, shares of its common stock having a maximum aggregate offering price of up to $ 75.0 million. As of December 31, 2023, the Company may issue and sell up to approximately $ 71.0 million in additional shares of its common stock under the ATM. Follow-On Offerings On November 21, 2022, the Company completed an underwritten public offering of 22,613,307 shares of its common stock at a price of $ 2.60 per share and, to certain investors in lieu of common stock, pre-funded warrants to purchase 6,236,693 shares of its common stock at a price of $ 2.599 per pre-funded warrant. The pre-funded warrants can be exercised at any time after issuance for an exercise price of $ 0.001 per share, subject to certain ownership limitations. In addition, the Company granted the underwriters a 30-day option to purchase up to an additional 4,327,500 shares of its common stock to cover overallotments, if any, at $ 2.60 per share. On November 29, 2022, the underwriters partially exercised the option and purchased an additional 2,816,409 shares of Company’s common stock. As of December 31, 2023, pre-funded warrants for 5,934,176 shares of common stock remained outstanding. . As of December 31, 2023, total shares of common stock reserved for issuance, on an as-if converted basis, are as follows: December 31, Outstanding stock options and awards 9,431,710 Outstanding pre-funded warrants 5,934,176 Shares available for further issuance under the 2021 Equity Incentive Plan 965,665 Shares available for further issuance under the 2021 Employee Stock Purchase Plan 1,405,394 Total 17,736,945

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Note 7. Stock-Based Compensation 2021 Equity Incentive Plan Under the Company's 2021 Equity Incentive Plan (2021 Plan), 4,000,000 shares of the Company’s common stock were initially reserved for issuance of equity awards to employees, directors, and consultants, under terms and provisions established by the board of directors. The number of shares of common stock available for issuance under the 2021 Plan automatically increases on the first day of January for a period of ten years , commencing on January 1, 2022, in an amount equal to the lesser of: 4,000,000 shares; 4 % of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the board of directors may determine. Total shares reserved and available for grant under the 2021 Plan as of December 31, 2023 are 965,665 . Stock Option Activity The following table summarizes stock option activity : Shares Weighted- Weighted- Aggregate (in dollars) (Years) (In thousands) Outstanding as of December 31, 2022 5,210,182 $ 10.01 Granted 3,311,758 $ 3.36 Exercised ( 10,875 ) $ 2.71 Cancelled ( 167,631 ) $ 5.85 Outstanding as of December 31, 2023 8,343,434 $ 7.47 8.12 $ 2,380 Exercisable as of December 31, 2023 3,821,798 $ 7.81 7.43 $ 1,700 The aggregate intrinsic value is the value of the Company’s closing stock price on the last trading day of the year in excess of the weighted-average exercise price multiplied by the number of options outstanding or exercisable. The total intrinsic value of options exercised during the years ended December 31, 2023 and 2022, was $ 36.7 thousand and $ 0.2 million. The weighted-average grant-date fair value of options granted during the years ended December 31, 2023 and 2022 was $ 2.62 and $ 9.80 per share. As of December 31, 2023, there was $ 25.0 million of unrecognized stock-based compensation cost related to stock options, which is expected to be recognized over an estimated weighted-average period of 2.5 years. Stock Option Valuation The fair value of the Company’s stock option awards is estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions: The assumptions used to determine the fair value of options granted were as follows. Each of these inputs is subjective, involve inherent uncertainties, and generally requires significant judgment. The assumptions used to determine the fair value of the awards represent management’s best estimates. Year Ended 2023 2022 Expected term (in years) 5.5 – 6.1 5.5 – 6.1 Expected volatility 93 % – 95 % 95 % – 97 % Risk-free interest rate 3.4 % – 4.5 % 1.6 % – 4.2 % Expected dividend yield — % — % Expected Term — The Company determines the expected term, which represents the period that stock-based awards are expected to be outstanding, in accordance with the simplified method due to its limited operating history, which is presumed to be the mid-point between the contractual term and the vesting period. Expected Volatility — As there is limited trading history for the Company’s common stock, the Company determines its computation of expected volatility on the historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. Risk-Free Interest Rate — The Company bases the risk-free interest rate on U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term assumption. Expected Dividend Yield — The expected dividend yield is assumed to be zero as the Company has never paid and has no plans to pay any dividends on its common stock. Restricted Stock Units Restricted stock units (RSUs) are awards that entitle the holder to receive freely tradable shares of the Company’ s common stock upon the completion of a specific period of continued service. RSUs are generally subject to forfeiture if employment terminates prior to the release of vesting restrictions. RSUs are valued at the market price of the underlying common stock on the date of grant. The Company recognizes noncash compensation expense for the fair value of RSUs on a straight-line basis over the requisite service period of the awards. The following table summarizes activity of RSUs granted to employees with service-based vesting under the 2021 Plan. Shares Weighted Weighted- Aggregate (in dollars) (Years) (In thousands) Unvested as of December 31, 2022 459,192 $ 4.07 Granted 911,813 $ 3.06 Vested ( 254,172 ) $ 3.61 Forfeited ( 28,557 ) $ 3.70 Unvested as of December 31, 2023 1,088,276 $ 3.34 1.19 $ 3,526 As of December 31, 2023, there was $ 3.0 million of unrecognized stock-based compensation cost related to RSUs, which is expected to be recognized over an estimated weighted-average period of 2.3 years. 2021 Employee Stock Purchase Plan Under the Company's 2021 Employee Stock Purchase Plan (ESPP), the Company initially reserved 800,000 shares for future issuance. The number of shares of common stock available for issuance under the ESPP automatically increases on the first day of each fiscal year beginning with 2022 in an amount equal to the lesser of: 800,000 shares; 1 % of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the board of directors may determine. As of December 31, 2023, 1,405,394 shares were reserved for future issuance under the ESPP. Under the Company’s ESPP, employees are generally eligible to participate and can purchase shares on each purchase date established semi-annually through payroll deductions at the lower of 85 % of the fair market value of the Company’s stock at the commencement of the offering period or each purchase date of the offering period. Each offering period spans 6 months . The ESPP permits eligible employees to purchase common stock through payroll deductions for up to 15 % of qualified compensation, up to an annual limit of $ 25,000 per the Internal Revenue Service. The first offering period commenced in January 2022. For the years ended December 30, 2023 and 2022, the stock-based compensation expense for ESPP was not material. Stock-Based Compensation The following table summarizes stock-based compensation recognized in the Company’s statements of operations and comprehensive loss: Year Ended 2023 2022 Research and development $ 7,039 $ 4,914 General and administrative 8,270 6,553 Total stock-based compensation $ 15,309 $ 11,467

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Note 8. Income Taxes No provision for or benefit from income taxes was recorded during the years ended December 31, 2023 and 2022. The Company has established a full valuation allowance against its net deferred tax assets due to the uncertainty regarding the realization of such assets. All losses to date have been incurred in the United States. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, as well as operating losses and tax credit carryforwards. Effective Tax Rate Reconciliation The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate and the effective tax rate reconciliation is as follows: December 31, 2023 2022 U.S. federal taxes at statutory rate 21.0 % 21.0 % State taxes (net of federal benefit) 1.2 1.2 Credits 3.7 2.8 Stock-based compensation ( 0.3 ) ( 0.3 ) Change in valuation allowance ( 24.4 ) ( 24.1 ) Other ( 1.2 ) ( 0.6 ) Total —% —% A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2023 2022 (In thousands) Balance at beginning of year $ 3,141 $ 1,470 Additions based on tax positions related to current year 1,423 1,588 Additions based on tax positions related to prior years — 83 Reductions for tax positions related to prior years ( 43 ) — Balance at end of year $ 4,521 $ 3,141 The Company does not expect that its uncertain tax positions will materially change in the next twelve months. The reversal of the uncertain tax benefits would not impact the Company’s effective tax rate as the Company continues to maintain a full valuation allowance against its deferred tax assets. The Company files tax returns in U.S. federal and state jurisdictions with varying statutes of limitations. Due to net operating loss and credit carryforwards, all of the tax years since inception through the 2023 tax year remain subject to examination by the U.S. federal and state authorities. The Company is currently not subject to any income tax audits by federal or state taxing authorities. Deferred Income Taxes The tax effects of significant items comprising the Company’s deferred income taxes are as follows : December 31, 2023 2022 (In thousands) Deferred tax assets: Net operating losses $ 52,757 $ 41,256 Capitalized research and development expenditure 29,318 17,045 Tax credits 15,047 9,347 Lease liability 2,613 3,176 Stock-based compensation 2,880 1,631 Accrued expenses and other 1,713 1,368 Total deferred tax assets 104,328 73,823 Valuation allowance ( 101,290 ) ( 71,129 ) Deferred tax assets, net of valuation allowance 3,038 2,694 Deferred tax liabilities: Right-of-use asset ( 2,098 ) ( 2,453 ) Property and equipment ( 940 ) ( 241 ) Net deferred tax assets $ — $ — Beginning January 1, 2022, the Tax Cuts and Jobs Act eliminated the option to deduct research and development expenditures in the current year and requires taxpayers to capitalize such expenses pursuant to Internal Revenue Code (IRC) Section 174. The capitalized expenses are amortized over a 5-year period for domestic expenses and a 15-year period for foreign expenses. The tax benefit of net operating losses, capitalized research expenses, temporary differences and credit carryforwards are recorded as an asset to the extent that the Company assesses that realization is more likely than not. Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. As a result of the Company’s recent history of operating losses, the Company believes that recognition of deferred tax assets arising from the above-mentioned future tax benefits is currently not likely to be realized and, accordingly, has provided a full valuation allowance. The valuation allowance increased by $ 30.2 million and $ 29.8 million during the years ended December 31, 2023 and 2022. The increase in valuation allowance during the year ended December 31, 2023, was primarily due to the increase in deferred tax assets from 2023 federal net operating losses and the IRC Section 174 capitalized expenses. Net Operating Loss and Tax Credit Carryforwards As of December 31, 2023, the Company’s net operating loss and tax carryforwards are summarized as follows: (In thousands) Amount Expiration in years Net operating losses, federal (post-December 31, 2017) $ 224,796 Do Not Expire Net operating losses, federal (pre-January 1, 2018) $ 3,093 Begins to Expire 2036 Net operating losses, state $ 63,212 Begins to Expire 2036 Tax credits, federal $ 14,730 Begins to Expire 2036 Tax credits, state $ 6,856 Do Not Expire Under Section 382 of the Internal Revenue Code of 1986, as amended, the ability to utilize net operating loss carryforwards or other tax attributes, such as research tax credits, in any taxable year may be limited if the Company has experienced an “ownership change”. This annual limitation may result in the expiration of net operating losses and credits before utilization. As of December 31, 2023, the Company concluded that there were no ownership changes during 2023. The Company’s ability to use its remaining net operating loss carryforwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership. The Company recognizes interest and penalties related to taxes and uncertain tax positions as a component of income tax expense. During the years ended December 31, 2023 and 2022, no interest and penalties were accrued by the Company.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	Note 9. Net Loss Per Share Basic and diluted loss per share are computed by dividing net loss by the weighted-average number of common shares outstanding during the reporting period. Basic weighted-average shares of common stock outstanding includes the weighted-average effect of the Company’s pre-funded warrants. The following potentially dilutive securities were excluded from the calculation of diluted net loss per share for the periods presented because the effect would have been anti-dilutive: December 31, 2023 2022 Outstanding stock options and restricted stock units 9,431,710 5,669,374 Restricted stock subject to future vesting — 853 Total 9,431,710 5,670,227

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Note 10. Subsequent Events On February 12, 2024, the Company completed an underwritten offering of 8,888,890 shares of its common stock at a price of $ 4.50 per share and, to an investor in lieu of common stock, pre-funded warrants to purchase 2,222,271 shares of its common stock at a price of $ 4.499 per each pre-funded warrant. The pre-funded warrants can be exercised at any time after issuance for an exercise price of $ 0.001 per share, subject to certain ownership limitations. The Company received net proceeds of approximately $ 46.5 million, after deducting underwriting discounts and commissions of approximately $ 3.0 million and offering expenses of approximately $ 0.5 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to, the valuation of equity-based awards and accrued expenses related to research and development activities. The Company bases its estimates on historical experience, the current economic environment, and on various other assumptions that are believed to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: Level 1 - Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 - Inputs other than quoted market prices included in Level 1 are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 - Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short-term nature.
Concentration of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentration of risk consist principally of cash, cash equivalents and marketable securities. The Company maintains deposits in cash and cash equivalents in federally insured financial institutions that it believes have high credit quality. Such deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and the issuers of its investments in marketable securities to the extent recorded in the balance sheets. The Company has not experienced any losses on its deposits of cash and cash equivalents.
Risks and Uncertainties	Risks and Uncertainties The Company is subject to certain risks including, but not limited to, the ability to obtain future financing, possible failure of ongoing and future clinical trials, the need to obtain regulatory approvals for its product candidates, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, competitive developments, protection of proprietary technology, the ability to make milestone, royalty or other payments due under licensing agreements, and the Company’s ability to attract and retain employees necessary to support its business plan.
Segment Information	Segment Information The Company views its operations and manages its business as one operating segment , which is the business of discovering and developing potential treatments that address the underlying drivers of heart disease. The Company’s long-lived assets are located in the United States.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents primarily consist of money market funds that are stated at fair value.
Restricted Cash	Restricted Cash The restricted cash primarily represents security deposits for the Company’s operating leases in South San Francisco, and Union City, California. The security deposits are in the form of a letter of credit secured by restricted cash.
Marketable Securities	Marketable Securities The Company invests in marketable securities, primarily securities issued by the U.S. government and its agencies, commercial paper and corporate bonds. All marketable securities have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company evaluates securities for impairment at the end of each reporting period. Factors considered in the evaluation include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospect of the issuer, and the Company’s intent and ability to hold the investment to allow for anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit-related is reported as a component of other comprehensive loss. Realized gains and losses are included in other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest earned on marketable securities is included in interest income.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years . Leasehold improvements are amortized over the shorter of the assets’ expected lives or the remaining lease term. Costs for capital assets not yet placed into service are capitalized as construction in progress and are not depreciated until the asset is placed in service. Upon retirement or sale, the cost of disposed assets and their related accumulated depreciation are removed from the balance sheets. Any resulting gains or losses on dispositions of property and equipment are included as a component of other income (expense), net, within the Company’s statements of operations and comprehensive loss. Repair and maintenance costs, which are not considered improvements and do not extend the useful life of property and equipment, are expensed as incurred.
Impairment for Long-Lived Assets	Impairment for Long-Lived Assets Long-lived assets, including construction in progress, are reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by comparing the carrying amount of an asset to the estimated undiscounted future net cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There was no impairment of long-lived assets for any of the periods presented.
Leases	Leases The Company determines if an arrangement is a lease at inception. Operating lease right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term at the commencement date of the lease. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less any lease incentive received. The Company uses the rate implicit in the lease in determining the present value of lease payments and, if that rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at the date of lease commencement. The incremental borrowing rate reflects the rate of interest that a lessee would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company’s non-lease components are primarily related to property taxes, insurance, and common area maintenance, which vary based on future outcomes, and are recognized as rent expense when incurred.
Research and Development Expense	Research and Development Expenses Research and development (R&D) costs are expensed as incurred. Research and development expenses include, among others, consulting fees, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocated facilities and overhead costs, fees related to licensing agreements, fees paid to contract research organizations (CRO) that conduct research and development activities on the Company’s behalf and costs related to compliance with regulatory requirements. Goods or services incurred for research and development activities that have not yet been invoiced are recorded as liabilities within accrued expenses and other current liabilities on the Company’s balance sheets. The Company has and may continue to acquire the rights to licensed technology that represents in-process research and development to use and develop in the commercialization of new product candidates. The upfront payments made to acquire licenses, product or rights, or payments made related to future milestone payments are recognized as research and development expenses provided that there is no alternative future use of the rights in other research and development projects, up to the point of regulatory approval. Milestone payments are expensed when the specific milestone has been achieved. Non-refundable advance payments for goods or services to be rendered as part of future research and development activities are capitalized on the Company’s balance sheets until the goods or services are received. Classification between prepaid expenses and other current assets and other non-current assets is based on an evaluation of when the goods will be delivered and/or services will be performed, with such amounts subsequently amortized to expense once incurred.
Stock-Based Compensation	Stock-Based Compensation The Company measures and records expense related to all equity awards granted to employees and non-employees in the statements of operations and comprehensive loss based on their grant date fair values, including stock options and restricted stock awards. For stock-based awards that vest subject to the satisfaction of a service requirement, the expense is recognized using the straight-line method over the requisite service period, which is generally the vesting period. Forfeitures are recognized as they occur. The fair value of restricted stock awards is determined on the date of grant based on the estimated fair value of the Company’s common stock on that date. For purposes of determining the estimated fair value of options granted to employees and nonemployees, the Company uses the Black-Scholes option pricing model. See Note 7 to the Company's financial statements for the specific assumptions used in applying the Black-Scholes valuation model.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded for deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. As of December 31, 2023 and 2022, the Company has recorded a full valuation allowance on its net deferred tax assets. Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties, if any, related to unrecognized tax benefits are included within the provision for income tax.
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 shares of the Company’s common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Basic shares of common stock outstanding include the weighted-average effect of the Company’s pre-funded warrants issued in November 2022 because the pre-funded warrants have a nominal exercise price. As the Company is in a loss position for the periods presented, diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive. Shares related to early exercised stock options that are subject to repurchase are excluded from the basic and diluted net loss per share calculation until the Company’s repurchase right lapses.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (a) is no longer an emerging growth company or (b) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently Adopted Accounting Standards and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which replaces the existing incurred loss impairment model with an expected credit loss model. This standard requires companies to recognize an allowance for credit losses on available-for-sale debt securities rather than the prior approach of recording a reduction to the carrying value of the asset. ASU 2016-13 became effective for the Company beginning January 1, 2023 . The adoption of this standard did no t have a material impact on the Company's financial statements. Recently Issued Accounting Pronouncements Note Yet Adopted In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09), which requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for the Company beginning January 1, 2025. The Company is evaluating the impact of this standard on its financial statements and related disclosures. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (ASU 2023-07), which improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. In addition, ASU 2023-07 enhances interim disclosure requirements, clarifies circumstances in which an entity can disclose multiple segment measures of profit or loss, provided new segment disclosure requirements for entities with a single reportable segment, and contains other disclosure requirements. ASU 2023-07 is effective for the Company beginning January 1, 2024. The Company is evaluating the impact of this standard on its financial statements and related disclosures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis	The following tables summarize the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy: December 31, 2023 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Money market funds Level 1 91 — — 91 U.S. treasuries Level 1 3,595 — — 3,595 Commercial paper Level 2 34,901 — ( 18 ) 34,883 Government agencies bonds Level 2 6,389 1 — 6,390 Marketable securities: U.S. treasuries Level 1 16,182 4 ( 15 ) 16,171 Commercial paper Level 2 2,971 — ( 2 ) 2,969 Government agencies bonds Level 2 39,897 6 ( 82 ) 39,821 Total financial assets $ 104,026 $ 11 $ ( 117 ) $ 103,920 December 31, 2022 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Cash equivalents Level 1 $ 20,532 $ — $ — $ 20,532 Money market funds Level 1 7,203 — — 7,203 Commercial paper Level 2 11,972 — ( 4 ) 11,968 Government agencies bonds Level 2 54,569 12 — 54,581 Marketable securities: U.S. treasuries Level 1 25,273 1 ( 147 ) 25,127 Commercial paper Level 2 43,605 4 ( 125 ) 43,484 Corporate bonds Level 2 2,696 — ( 18 ) 2,678 Government agencies bonds Level 2 37,770 9 ( 110 ) 37,669 Total financial assets $ 203,620 $ 26 $ ( 404 ) $ 203,242

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net, consists of the following: December 31, December 31, (In thousands) Leasehold improvements $ 25,608 $ 23,605 Laboratory equipment 19,973 20,537 Manufacturing equipment 17,716 17,468 Construction in progress 1,730 3,128 Computer equipment and software 1,614 1,060 Furniture and fixtures 976 910 Total property and equipment $ 67,617 $ 66,708 Less: accumulated depreciation and amortization ( 24,340 ) ( 15,676 ) Total property and equipment, net $ 43,277 $ 51,032
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: December 31, December 31, (In thousands) Accrued compensation and related expenses $ 8,700 $ 6,299 Accrued research and development expenses 2,583 3,214 Accrued professional services 743 482 ESPP deduction liability 88 124 Accrued facility management services 185 — Other current liabilities 485 545 Total accrued and other current liabilities $ 12,784 $ 10,664 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: December 31, December 31, (In thousands) Prepaid expenses 5,783 4,044 Tax credit receivable — 2,245 Other current assets 1,157 938 Total prepaid expenses and other current assets $ 6,940 $ 7,227
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following: December 31, December 31, (In thousands) Prepaid expenses 5,783 4,044 Tax credit receivable — 2,245 Other current assets 1,157 938 Total prepaid expenses and other current assets $ 6,940 $ 7,227

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Summary of Operating Lease Activity	Information related to operating lease activity during the year ended December 31, 2023 was as follows (in thousands): Year Ended December 31, 2023 2022 Operating lease cost $ 4,356 $ 3,714 Variable lease cost 1,265 1,209 Short-term lease cost 5 952 Total lease cost $ 5,626 $ 5,875 Operating lease right-of-use assets obtained in exchange for lease obligations $ 1,448 $ 2,224 Cash paid for amounts included in the measurement of lease liabilities $ 5,347 $ 4,293
Summary of Future Minimum Lease Payments Under Operating Lease	Future minimum lease payments under the Company’s operating leases as of December 31, 2023 were as follows: Amount (In thousands) 2024 $ 5,277 2025 2,445 2026 1,386 2027 1,428 2028 1,471 Thereafter 4,006 Total undiscounted future minimum lease payments $ 16,013 Imputed interest ( 3,589 ) Total operating lease liabilities $ 12,424

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	As of December 31, 2023, total shares of common stock reserved for issuance, on an as-if converted basis, are as follows: December 31, Outstanding stock options and awards 9,431,710 Outstanding pre-funded warrants 5,934,176 Shares available for further issuance under the 2021 Equity Incentive Plan 965,665 Shares available for further issuance under the 2021 Employee Stock Purchase Plan 1,405,394 Total 17,736,945

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity : Shares Weighted- Weighted- Aggregate (in dollars) (Years) (In thousands) Outstanding as of December 31, 2022 5,210,182 $ 10.01 Granted 3,311,758 $ 3.36 Exercised ( 10,875 ) $ 2.71 Cancelled ( 167,631 ) $ 5.85 Outstanding as of December 31, 2023 8,343,434 $ 7.47 8.12 $ 2,380 Exercisable as of December 31, 2023 3,821,798 $ 7.81 7.43 $ 1,700
Summary of Fair Value of Stock Option Awards	The assumptions used to determine the fair value of the awards represent management’s best estimates. Year Ended 2023 2022 Expected term (in years) 5.5 – 6.1 5.5 – 6.1 Expected volatility 93 % – 95 % 95 % – 97 % Risk-free interest rate 3.4 % – 4.5 % 1.6 % – 4.2 % Expected dividend yield — % — %
Summary of Restricted Stock Activity	The following table summarizes activity of RSUs granted to employees with service-based vesting under the 2021 Plan. Shares Weighted Weighted- Aggregate (in dollars) (Years) (In thousands) Unvested as of December 31, 2022 459,192 $ 4.07 Granted 911,813 $ 3.06 Vested ( 254,172 ) $ 3.61 Forfeited ( 28,557 ) $ 3.70 Unvested as of December 31, 2023 1,088,276 $ 3.34 1.19 $ 3,526
Summary of Stock-based Compensation	The following table summarizes stock-based compensation recognized in the Company’s statements of operations and comprehensive loss: Year Ended 2023 2022 Research and development $ 7,039 $ 4,914 General and administrative 8,270 6,553 Total stock-based compensation $ 15,309 $ 11,467

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Effective Tax Rate Reconciliation	The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate and the effective tax rate reconciliation is as follows: December 31, 2023 2022 U.S. federal taxes at statutory rate 21.0 % 21.0 % State taxes (net of federal benefit) 1.2 1.2 Credits 3.7 2.8 Stock-based compensation ( 0.3 ) ( 0.3 ) Change in valuation allowance ( 24.4 ) ( 24.1 ) Other ( 1.2 ) ( 0.6 ) Total —% —%
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2023 2022 (In thousands) Balance at beginning of year $ 3,141 $ 1,470 Additions based on tax positions related to current year 1,423 1,588 Additions based on tax positions related to prior years — 83 Reductions for tax positions related to prior years ( 43 ) — Balance at end of year $ 4,521 $ 3,141
Schedule of Deferred Income Taxes	The tax effects of significant items comprising the Company’s deferred income taxes are as follows : December 31, 2023 2022 (In thousands) Deferred tax assets: Net operating losses $ 52,757 $ 41,256 Capitalized research and development expenditure 29,318 17,045 Tax credits 15,047 9,347 Lease liability 2,613 3,176 Stock-based compensation 2,880 1,631 Accrued expenses and other 1,713 1,368 Total deferred tax assets 104,328 73,823 Valuation allowance ( 101,290 ) ( 71,129 ) Deferred tax assets, net of valuation allowance 3,038 2,694 Deferred tax liabilities: Right-of-use asset ( 2,098 ) ( 2,453 ) Property and equipment ( 940 ) ( 241 ) Net deferred tax assets $ — $ —
Summary of Net Operating Loss and Tax Carryforwards	As of December 31, 2023, the Company’s net operating loss and tax carryforwards are summarized as follows: (In thousands) Amount Expiration in years Net operating losses, federal (post-December 31, 2017) $ 224,796 Do Not Expire Net operating losses, federal (pre-January 1, 2018) $ 3,093 Begins to Expire 2036 Net operating losses, state $ 63,212 Begins to Expire 2036 Tax credits, federal $ 14,730 Begins to Expire 2036 Tax credits, state $ 6,856 Do Not Expire

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following potentially dilutive securities were excluded from the calculation of diluted net loss per share for the periods presented because the effect would have been anti-dilutive: December 31, 2023 2022 Outstanding stock options and restricted stock units 9,431,710 5,669,374 Restricted stock subject to future vesting — 853 Total 9,431,710 5,670,227

Organization and Description _2

Organization and Description of the Business - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 12, 2024	Dec. 31, 2023	Dec. 31, 2022
Organization And Description Of Business [Line Items]
Accumulated deficit		$ (403,282)	$ (279,198)
Net loss		(124,084)	$ (123,665)
Cash, cash equivalents and investments in marketable securities		104,600
Net proceeds from offering		$ 3,868
Subsequent Events | Underwritten Offering
Organization And Description Of Business [Line Items]
Net proceeds from offering	$ 46,500

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Significant Accounting Policies [Line Items]
Impairment of long lived assets	$ 0	$ 0
ASU 2016-13
Significant Accounting Policies [Line Items]
Accounting standards update, adopted [true false]	true
Accounting standards update, immaterial effect [true false]	true
Accounting standards update, adoption date	Jan. 01, 2023
Minimum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Maximum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 104,026	$ 203,620
Unrealized Gain	11	26
Unrealized Loss	(117)	(404)
Fair Value	103,920	203,242
Cash Equivalents | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		20,532
Fair Value		20,532
Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	91	7,203
Fair Value	91	7,203
U.S. Treasuries | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	3,595
Fair Value	3,595
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	34,901	11,972
Unrealized Loss	(18)	(4)
Fair Value	34,883	11,968
Government Agencies Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	6,389	54,569
Unrealized Gain	1	12
Fair Value	6,390	54,581
U.S. Treasuries | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	16,182	25,273
Unrealized Gain	4	1
Unrealized Loss	(15)	(147)
Fair Value	16,171	25,127
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	2,971	43,605
Unrealized Gain		4
Unrealized Loss	(2)	(125)
Fair Value	2,969	43,484
Corporate Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		2,696
Unrealized Loss		(18)
Fair Value		2,678
Government Agencies Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	39,897	37,770
Unrealized Gain	6	9
Unrealized Loss	(82)	(110)
Fair Value	$ 39,821	$ 37,669

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charges on marketable securities related to other-than-temporary	$ 0
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale marketable securities contractual maturities term	1 year

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total property and equipment	$ 67,617	$ 66,708
Less: accumulated depreciation and amortization	(24,340)	(15,676)
Total property and equipment, net	43,277	51,032
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	25,608	23,605
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	19,973	20,537
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	17,716	17,468
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	1,730	3,128
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment	1,614	1,060
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 976	$ 910

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 8.7	$ 6.5

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related expenses	$ 8,700	$ 6,299
Accrued research and development expenses	2,583	3,214
Accrued professional services	743	482
ESPP deduction liability	88	124
Accrued facility management services	185
Other current liabilities	485	545
Total accrued and other current liabilities	$ 12,784	$ 10,664

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Prepaid expenses	$ 5,783	$ 4,044
Tax credit receivable		2,245
Other Assets, Current	1,157	938
Total prepaid expenses and other current assets	$ 6,940	$ 7,227

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - RenewalOption	1 Months Ended
	Oct. 31, 2023	May 31, 2022	Nov. 30, 2021	Feb. 28, 2021	Dec. 31, 2016	Dec. 31, 2023
Commitments And Contingencies [Line Items]
Weighted-average remaining lease term						5 years 1 month 6 days
Weighted-average discount rate						9.30%
Union City Facility
Commitments And Contingencies [Line Items]
Number of lease renewal term				1
Lease renewal term				5 years
Lease commenced month and year				2021-05
Term of lease				10 years
Office and Laboratory Space | South San Francisco, California
Commitments And Contingencies [Line Items]
Lease expiration month and year					2025-05
Number of lease renewal term					2
Lease renewal term					5 years
Additional Office and Laboratory Space | South San Francisco, California
Commitments And Contingencies [Line Items]
Lease Expiration Date		Dec. 31, 2022	Jun. 30, 2022
Second Amendment | South San Francisco, California
Commitments And Contingencies [Line Items]
Lease Expiration Date	Nov. 30, 2024

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Operating Lease Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 4,356	$ 3,714
Variable lease cost	1,265	1,209
Short-term lease cost	5	952
Total lease cost	5,626	5,875
Operating lease right-of-use assets obtained in exchange for lease obligations	1,448	2,224
Cash paid for amounts included in the measurement of lease liabilities	$ 5,347	$ 4,293

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Future Minimum Lease Payments Under Operating Leases (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 5,277
2025	2,445
2026	1,386
2027	1,428
2028	1,471
Thereafter	4,006
Total undiscounted future minimum lease payments	16,013
Imputed interest	(3,589)
Total operating lease liabilities	$ 12,424

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Nov. 29, 2022	Nov. 21, 2022	Aug. 10, 2022	Dec. 31, 2023
Class Of Stock [Line Items]
Common stock voting rights				The holders of common stock are entitled to one vote per share on all matters to be voted on by the stockholders of the Company and are entitled to dividends, if and when declared by the board of directors, subject to the prior rights of the preferred stockholders.
Pre-funded warrants, shares of common stock exercised				5,934,176
Follow On Offering
Class Of Stock [Line Items]
Number of common shares	2,816,409	22,613,307
Common stock, per share		$ 2.6
Warrant purchase common stock		4,327,500
Pre Funded Warrant | Follow On Offering
Class Of Stock [Line Items]
Warrants issued to purchase shares of common stock		6,236,693
Class of warrant price per share		$ 2.599
Warrants, exercise price		$ 0.001
Common Stock | At-the-Market Equity Offering
Class Of Stock [Line Items]
Maximum aggregate offering price			$ 75
Maximum additional shares issuable				$ 71

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2023	Jul. 31, 2021
Class Of Stock [Line Items]
Common stock reserved for issuance	17,736,945
2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,405,394	800,000
2021 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	4,000,000
Outstanding Pre-Funded Warrants
Class Of Stock [Line Items]
Common stock reserved for issuance	5,934,176
Outstanding Stock Options and Awards
Class Of Stock [Line Items]
Common stock reserved for issuance	9,431,710
Shares Available for Further Issuance Under the Employee Stock Purchase Plan | 2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,405,394
Shares Available For Further Issuance Under The Equity Incentive Plan | 2021 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	965,665

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Jul. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	17,736,945
Intrinsic value of options exercised	$ 36,700	$ 200,000
Weighted-average grant-date fair value of options granted	$ 2.62	$ 9.80
Unrecognized stock-based compensation	$ 25,000,000
Weighted-average period	2 years 6 months
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 3,000,000
Weighted-average period	2 years 3 months 18 days
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	1,405,394		800,000
Participants to purchase common stock through payroll deduction maximum percentage of eligible compensation	15%
Participants to purchase shares through payroll deduction at lower percentage of fair market value	85%
Number of shares of common stock that may be issued in accordance with the plan	800,000
Percentage of shares of common stock outstanding on last day of immediately preceding year	1%
Participants to purchase common stock through payroll deduction annual limit of eligible compensation	$ 25,000
Weighted-average period	6 months
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	4,000,000
Common stock shares available for issuance period	10 years
Number of shares of common stock that may be issued in accordance with the plan	4,000,000
Percentage of shares of common stock outstanding on last day of immediately preceding year	4%
Shares reserved and available for grant	965,665

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2021 Equity Incentive Plan $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares, Outstanding Beginning Balance | shares	5,210,182
Granted | shares	3,311,758
Exercised | shares	(10,875)
Cancelled | shares	(167,631)
Shares, Outstanding Ending Balance | shares	8,343,434
Shares, Exercisable as of December 31, 2023 | shares	3,821,798
Weighted-Average Exercise Price Per Share, Outstanding Beginning Balance | $ / shares	$ 10.01
Granted | $ / shares	3.36
Exercised | $ / shares	2.71
Cancelled | $ / shares	5.85
Weighted-Average Exercise Price Per Share, Outstanding Ending Balance | $ / shares	7.47
Weighted-Average Exercise Price Per Share, Exercisable as of December 31, 2023 | $ / shares	$ 7.81
Weighted-Average Remaining Contractual Life, Outstanding	8 years 1 month 13 days
Weighted-Average Remaining Contractual Life, Exercisable as of December 31, 2023	7 years 5 months 4 days
Aggregate Intrinsic Value, Outstanding | $	$ 2,380
Aggregate Intrinsic Value, Exercisable as of December 31, 2023 | $	$ 1,700

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Fair Value of Stock Option Awards (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	93%	95%
Expected volatility, maximum	95%	97%
Risk-free interest rate, minimum	3.40%	1.60%
Risk free interest rate, maximum	4.50%	4.20%
Expected dividend yield	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 6 months
Maximum
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

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - 2021 Equity Incentive Plan - Restricted Stock $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested as of December 31, 2022 | shares	459,192
Granted | shares	911,813
Vested | shares	(254,172)
Forfeited | shares	(28,557)
Unvested as of December 31, 2023 | shares	1,088,276
Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2022 | $ / shares	$ 4.07
Granted | $ / shares	3.06
Vested | $ / shares	3.61
Forfeited | $ / shares	3.7
Unvested as of December 31, 2023 | $ / shares	$ 3.34
Weighted-Average Remaining Contractual Life, Unvested	1 year 2 months 8 days
Aggregate Intrinsic Value, Unvested | $	$ 3,526

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 15,309	$ 11,467
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	7,039	4,914
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 8,270	$ 6,553

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income taxes expense	$ 0	$ 0
Increase in valuation allowance, deferred tax assets	30,200,000	29,800,000
Interest and penalties related to taxes and uncertain tax positions	$ 0	$ 0

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S. federal taxes at statutory rate	21%	21%
State taxes (net of federal benefit)	1.20%	1.20%
Credits	3.70%	2.80%
Stock-based compensation	(0.30%)	(0.30%)
Change in valuation allowance	(24.40%)	(24.10%)
Other	(1.20%)	(0.60%)

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 3,141	$ 1,470
Additions based on tax positions related to current year	1,423	1,588
Additions based on tax positions related to prior years		83
Reductions for tax positions related to prior years	(43)
Balance at end of year	$ 4,521	$ 3,141

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating losses	$ 52,757	$ 41,256
Capitalized research and development expenditure	29,318	17,045
Tax credits	15,047	9,347
Lease liability	2,613	3,176
Stock-based compensation	2,880	1,631
Accrued expenses and other	1,713	1,368
Total deferred tax assets	104,328	73,823
Valuation allowance	(101,290)	(71,129)
Deferred tax assets, net of valuation allowance	3,038	2,694
Deferred tax liabilities:
Right-of-use asset	(2,098)	(2,453)
Property and equipment	$ (940)	$ (241)

Income Taxes - Summary of Net O

Income Taxes - Summary of Net Operating Loss and Tax Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Operating Loss Carryforwards [Line Items]
Net operating losses, state expiration begin year	2036
Tax credits, federal expiration begin year	2036
Tax credits, state expiration description	Do Not Expire
Federal
Operating Loss Carryforwards [Line Items]
Tax credits	$ 14,730
State
Operating Loss Carryforwards [Line Items]
Net operating losses	63,212
Tax credits	$ 6,856
Post-December 31, 2017
Operating Loss Carryforwards [Line Items]
Net operating losses, federal expiration description	Do Not Expire
Post-December 31, 2017 | Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 224,796
Pre-January 1, 2018
Operating Loss Carryforwards [Line Items]
Net operating losses, federal expiration begin year	2036
Pre-January 1, 2018 | Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 3,093

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share	9,431,710	5,670,227
Outstanding Stock Options And Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share	9,431,710	5,669,374
Restricted Stock Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share		853

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 12, 2024	Dec. 31, 2023
Subsequent Event [Line Items]
Net proceeds from offering		$ 3,868
Subsequent Events | Feb 2024 Follow-On Offering
Subsequent Event [Line Items]
Number of common shares	8,888,890
Common stock, per share	$ 4.5
Net proceeds from offering	$ 46,500
Underwriting discounts and commissions	3,000
Offering expenses	$ 500
Subsequent Events | Pre Funded Warrant | Feb 2024 Follow-On Offering
Subsequent Event [Line Items]
Warrants issued to purchase shares of common stock	2,222,271
Class of warrant price per share	$ 4.499
Warrants, exercise price	$ 0.001