Tenaya Therapeutics (TNYA) 10-Q 6 Nov 24 2024 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Oct. 31, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Registrant Name	TENAYA THERAPEUTICS, INC.
Entity Central Index Key	0001858848
Entity File Number	001-40656
Entity Incorporation, State or Country Code	DE
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
Current Fiscal Year End Date	--12-31
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
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	TNYA
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		79,220,516

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 8,231	$ 45,681
Short-term investments in marketable securities	71,238	58,961
Prepaid expenses and other current assets	5,861	6,940
Total current assets	85,330	111,582
Property and equipment, net	37,753	43,277
Operating lease right-of-use assets	12,626	9,979
Other noncurrent assets	4,873	5,677
Total assets	140,582	170,515
Current liabilities:
Accounts payable	5,839	5,630
Accrued and other current liabilities	7,327	12,784
Operating lease liabilities, current	3,011	4,319
Total current liabilities	16,177	22,733
Operating lease liabilities, noncurrent	11,527	8,105
Other noncurrent liabilities	276	253
Total liabilities	27,980	31,091
Commitments and contingencies (Note 4)
Stockholders' equity:
Common stock	8	7
Additional paid-in capital	603,093	542,805
Accumulated other comprehensive loss	76	(106)
Accumulated deficit	(490,575)	(403,282)
Total stockholders' equity	112,602	139,424
Total liabilities and stockholders' equity	$ 140,582	$ 170,515

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating expenses:
Research and development	$ 20,350	$ 23,091	$ 68,054	$ 75,173
General and administrative	6,361	7,829	23,242	24,574
Total operating expenses	26,711	30,920	91,296	99,747
Loss from operations	(26,711)	(30,920)	(91,296)	(99,747)
Other income, net:
Interest income	1,080	1,776	3,925	5,586
Other income (loss), net	(3)	1	78	12
Total other income, net	1,077	1,777	4,003	5,598
Net loss before income tax expense	(25,634)	(29,143)	(87,293)	(94,149)
Net loss	(25,634)	(29,143)	(87,293)	(94,149)
Other comprehensive income (loss):
Net unrealized gain (loss) on marketable securities	143	72	182	117
Comprehensive loss	$ (25,491)	$ (29,071)	$ (87,111)	$ (94,032)
Net loss per share, basic	$ (0.3)	$ (0.39)	$ (1.04)	$ (1.28)
Net loss per share, diluted	$ (0.3)	$ (0.39)	$ (1.04)	$ (1.28)
Weighted-average shares used in computing net loss per share, basic	86,162,841	73,924,937	84,290,747	73,579,200
Weighted-average shares used in computing net loss per share, diluted	86,162,841	73,924,937	84,290,747	73,579,200

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2022	$ 243,376	$ 7	$ 522,945	$ (378)	$ (279,198)
Balance, shares at Dec. 31, 2022		66,857,113
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares		8,311
Vesting of early exercised stock options	1		1
Stock-based compensation	3,514		3,514
Other comprehensive income (loss)	258			258
Net loss	(31,737)				(31,737)
Balance at Mar. 31, 2023	215,412	$ 7	526,460	(120)	(310,935)
Balance, shares at Mar. 31, 2023		66,865,424
Balance at Dec. 31, 2022	243,376	$ 7	522,945	(378)	(279,198)
Balance, shares at Dec. 31, 2022		66,857,113
Net loss	(94,149)
Balance at Sep. 30, 2023	164,884	$ 7	538,485	(261)	(373,347)
Balance, shares at Sep. 30, 2023		68,111,019
Balance at Mar. 31, 2023	215,412	$ 7	526,460	(120)	(310,935)
Balance, shares at Mar. 31, 2023		66,865,424
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 pursuant to employee stock purchase plan	282		282
Issuance of common stock pursuant to employee stock purchase plan, shares		150,575
Issuance of common stock upon exercise of pre-funded warrants, shares		302,517
Issuance of common stock upon exercise of stock options	29		29
Issuance of common stock upon exercise of stock options, shares		10,875
Stock-based compensation	3,831		3,831
Other comprehensive income (loss)	(213)			(213)
Net loss	(33,269)				(33,269)
Balance at Jun. 30, 2023	189,940	$ 7	534,470	(333)	(344,204)
Balance, shares at Jun. 30, 2023		67,865,158
Issuance of common stock upon vesting of restricted stock units		245,861
Stock-based compensation	4,015		4,015
Other comprehensive income (loss)	72			72
Net loss	(29,143)				(29,143)
Balance at Sep. 30, 2023	164,884	$ 7	538,485	(261)	(373,347)
Balance, shares at Sep. 30, 2023		68,111,019
Balance at Dec. 31, 2023	139,424	$ 7	542,805	(106)	(403,282)
Balance, shares at Dec. 31, 2023		68,330,342
Issuance of common stock and pre-funded warrants, net of issuance costs	46,762	$ 1	46,761
Issuance of common stock and pre-funded warrants, net of issuance costs, shares		8,888,890
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares		246,708
Issuance of common stock upon exercise of stock options and vesting of restricted stock units	11		11
Issuance of common stock upon exercise of pre-funded warrants	1		1
Issuance of common stock upon exercise of pre-funded warrants, shares		1,051,594
Stock-based compensation	4,224		4,224
Other comprehensive income (loss)	(14)			(14)
Net loss	(32,228)				(32,228)
Balance at Mar. 31, 2024	158,180	$ 8	593,802	(120)	(435,510)
Balance, shares at Mar. 31, 2024		78,517,534
Balance at Dec. 31, 2023	139,424	$ 7	542,805	(106)	(403,282)
Balance, shares at Dec. 31, 2023		68,330,342
Net loss	(87,293)
Balance at Sep. 30, 2024	112,602	$ 8	603,093	76	(490,575)
Balance, shares at Sep. 30, 2024		79,220,516
Balance at Mar. 31, 2024	158,180	$ 8	593,802	(120)	(435,510)
Balance, shares at Mar. 31, 2024		78,517,534
Issuance of common stock pursuant to employee stock purchase plan	554		554
Issuance of common stock pursuant to employee stock purchase plan, shares		320,951
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares		28,952
Issuance of common stock upon exercise of stock options and vesting of restricted stock units	30		30
Stock-based compensation	4,611		4,611
Other comprehensive income (loss)	53			53
Net loss	(29,431)				(29,431)
Balance at Jun. 30, 2024	133,997	$ 8	598,997	(67)	(464,941)
Balance, shares at Jun. 30, 2024		78,867,437
Issuance of common stock upon exercise of stock options and vesting of restricted stock units, shares		353,079
Issuance of common stock upon exercise of stock options and vesting of restricted stock units	14		14
Issuance of warrant	175		175
Stock-based compensation	3,907		3,907
Other comprehensive income (loss)	143			143
Net loss	(25,634)				(25,634)
Balance at Sep. 30, 2024	$ 112,602	$ 8	$ 603,093	$ 76	$ (490,575)
Balance, shares at Sep. 30, 2024		79,220,516

Condensed Statements of Stock_2

Condensed Statements of Stockholders' Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Jun. 30, 2023
Follow On Offering
Stock issuance costs	$ 3,236
At The Market Sales
Stock issuance costs		$ 120

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (87,293)	$ (94,149)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,379	6,506
Amortization (accretion) of premium (discount) on marketable securities	56	(1,371)
Stock-based compensation	12,742	11,360
Non-cash operating lease expense	2,655	2,326
Other	243	157
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,026	2,013
Other noncurrent assets	600	(658)
Accounts payable	120	(2,977)
Accrued and other current liabilities	(5,453)	(300)
Operating lease liabilities	(3,188)	(3,055)
Net cash used in operating activities	(72,113)	(80,148)
Cash flows from investing activities:
Purchases of property and equipment	(821)	(845)
Purchases of marketable securities	(85,058)	(40,998)
Proceeds from maturities of marketable securities	72,890	105,484
Other	17	(7)
Net cash (used in) provided by investing activities	(12,972)	63,634
Cash flows from financing activities:
Proceeds from issuance of common stock and pre-funded warrants in follow-on offering, net of issuance costs	46,762
Proceeds from exercise of stock options and employee stock purchase plan	609	311
Proceeds from exercises of pre-funded warrants	1
Proceeds from at-the-market sales, net of issuance costs	0	3,868
Payment of accrued offering costs	0	(501)
Net cash provided by financing activities	47,372	3,678
Net change in cash, cash equivalents and restricted cash	(37,713)	(12,836)
Cash and cash equivalents and restricted cash at beginning of period	46,363	95,671
Cash and cash equivalents and restricted cash at end of period	8,650	82,835
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	8,231	82,153
Restricted cash included in other noncurrent assets	419	682
Cash, cash equivalents and restricted cash	8,650	82,835
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment included in accounts payable and accrued and other current liabilities	334	$ 309
Issuance of warrant in connection with Loan Agreement	$ 175

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (25,634)	$ (29,431)	$ (32,228)	$ (29,143)	$ (33,269)	$ (31,737)	$ (87,293)	$ (94,149)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization and Description of

Organization and Description of the Business	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	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 September 30, 2024, the Company had an accumulated deficit of $ 490.6 million. The Company incurred a net loss of $ 87.3 million and $ 94.1 million during the nine months ended September 30, 2024 and 2023, respectively. The Company had $ 79.5 million of cash, cash equivalents and investments in marketable securities as of September 30, 2024. On August 6, 2024, the Company entered into a Loan Agreement with Silicon Valley Bank (SVB), a division of First-Citizens Bank & Trust Company (the Loan Agreement). As of the filing date of this periodic report, under the Loan Agreement, the Company has the right to draw down $ 20.0 million at its discretion, up to an additional $ 5.0 million upon the satisfaction of certain milestones and up to an additional $ 20.0 million that may be available at SVB's discretion, subject to specified conditions. See Note 6, Term Loan , for further details. 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, collaborative agreements or other sources of financing. Management believes that its existing cash, cash equivalents and investments in marketable securities as of September 30, 2024, along with the $ 20.0 million of funds available under its Loan Agreement with SVB, will be sufficient to fund the Company’s operations for at least the next twelve months following the date these condensed financial statements are filed with the Securities and Exchange Commission (SEC).

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and follow the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. The interim condensed balance sheet as of September 30, 2024, the interim condensed statements of operations and comprehensive loss, stockholders’ equity and cash flows for the nine months ended September 30, 2024 and 2023 are unaudited. These unaudited interim condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and reflect all adjustments that are necessary for the fair statement of the Company’s financial position, results of operations and cash flows for the interim periods presented. The condensed results of operations for the nine months ended September 30, 2024, are not necessarily indicative of the results to be expected for the full year or for any other future annual or interim period. The condensed balance sheet as of December 31, 2023, included herein was derived from the audited financial statements as of that date. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and the related notes thereto for the year ended December 31, 2023, included in Company’s Annual Report on Form 10-K, filed with the SEC on March 18, 2024. Use of Estimates The preparation of condensed 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 condensed 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, 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. Significant Accounting Policies There have been no material revisions to the Company’s significant accounting policies described in Note 2 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Recently Issued Accounting Pronouncements Not Yet Adopted In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (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, provides new segment disclosure requirements for entities with a single reportable segment, and contains other disclosure requirements. ASU 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The Company is evaluating the impact of this standard on its financial statements and related disclosures. 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.

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	3. Balance Sheet Components Property and Equipment, Net Property and equipment, net consists of the following: September 30, December 31, (In thousands) Leasehold improvements $ 25,728 $ 25,608 Laboratory equipment 20,201 19,973 Manufacturing equipment 17,716 17,716 Construction in progress 2,150 1,730 Computer equipment and software 1,664 1,614 Furniture and fixtures 981 976 Total property and equipment $ 68,440 $ 67,617 Less: accumulated depreciation and amortization ( 30,687 ) ( 24,340 ) Total property and equipment, net $ 37,753 $ 43,277 Depreciation and amortization expense for the three months ended September 30, 2024 and 2023 was $ 2.1 million and $ 2.2 million, respectively. Depreciation and amortization expense for each of the nine months ended September 30, 2024 and 2023 was $ 6.4 million and $ 6.5 million, respectively. Accrued and Other Current Liabilities Accrued and other current liabilities consist of the following: September 30, December 31, (In thousands) Accrued compensation and related expenses $ 4,735 $ 8,700 Accrued research and development expenses 1,566 2,583 Accrued professional services 389 743 Accrued taxes 202 280 Accrued facility management services — 185 Other current liabilities 435 293 Total accrued and other current liabilities $ 7,327 $ 12,784 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: September 30, December 31, (In thousands) Prepaid expenses $ 4,458 $ 5,783 Other current assets 1,403 1,157 Total prepaid expenses and other current assets $ 5,861 $ 6,940

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	4. 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 was initially set to expire in May 2025 with two five-year renewal options. In June 2024, the Company amended the lease to extend the term to November 2027 . Pursuant to the terms of the amended lease, the Company has one remaining five-year renewal option. In February 2021, the Company entered into a lease agreement for office and manufacturing space in Union City, California. 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 sublease agreement for office and laboratory space in South San Francisco, California. The lease was initially set to expire on June 30, 2022 . In May 2022, the Company amended the lease to extend the term for the existing sublease premises through December 31, 2022 . Pursuant to the terms of the amendment, the Company also subleased additional office and laboratory space at the same subleased premises 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 subleased premises through November 30, 2024 . Information related to operating lease activity during the three and nine months ended September 30, 2024 was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 (In thousands) Operating lease cost $ 1,356 $ 1,090 $ 3,506 $ 3,271 Variable lease cost 377 324 1,079 919 Short-term lease cost — — — 5 Total lease cost $ 1,733 $ 1,414 $ 4,585 $ 4,195 Operating lease right-of-use assets obtained in exchange for lease obligations $ 5,302 $ — Cash paid for amounts included in the measurement of lease liabilities $ 4,039 $ 4,000 As of September 30, 2024, the Company’s operating leases had a weighted average remaining lease term of 4.9 years and a weighted average discount rate of 8.9 %. 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 September 30, 2024 were as follows: Amount (In thousands) 2024 (remaining 3 months) $ 1,238 2025 3,861 2026 3,864 2027 3,775 2028 1,471 Thereafter 4,006 Total undiscounted future minimum lease payments $ 18,215 Imputed interest ( 3,677 ) Total operating lease liabilities $ 14,538 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. In general, 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 September 30, 2024. In the normal course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may be obligated to 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 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 September 30, 2024, the Company did not have any material indemnification claims that were probable and consequently has not recorded any related liabilities .

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	5. Stock-Based Compensation 2024 Inducement Equity Incentive Plan In September 2024, the Board of Directors (the Board) adopted the Company's 2024 Inducement Equity Incentive Plan (the Inducement Plan), and subject to the adjustment provisions of the Inducement Plan, reserved 1,200,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan. The Inducement Plan allows the Company to make equity awards to prospective employees of the Company as an inducement to such individual's commencement of employment with the Company. As of September 30, 2024, no shares have been issued under the Inducement Plan. 2021 Equity Incentive Plan Under the Company's 2021 Equity Incentive Plan (the 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. 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 Inducement Plan and 2021 Plan as of September 30, 2024 are 1,200,000 and 1,355,277 , respectively. Stock Option Activity The following table summarizes stock option activity: Shares Weighted- (in dollars) Outstanding as of December 31, 2023 8,343,434 $ 7.47 Granted 2,470,100 $ 5.13 Exercised ( 32,195 ) $ 1.69 Cancelled ( 1,180,558 ) $ 8.21 Outstanding as of September 30, 2024 9,600,781 $ 6.80 Stock option awards granted to employees generally vest over a four-year period. The contractual term of stock option awards is generally 10 years from the grant date. 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: Three Months Ended Nine Months Ended 2024 2023 2024 2023 Expected term (in years) N/A 6.1 6.0 – 6.1 5.5 – 6.1 Expected volatility N/A 94 % 92 % – 93 % 94 % – 95 % Risk-free interest rate N/A 4.0 % – 4.4 % 3.9 % – 4.5 % 3.4 % – 4.4 % Expected dividend yield N/A — % — % — % N/A - not applicable as no stock option awards were granted in the period presented. 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 generally vest over a two to four year period and are 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 (in dollars) Unvested as of December 31, 2023 1,088,276 $ 3.34 Granted 1,314,865 $ 4.52 Vested ( 596,544 ) $ 3.59 Forfeited ( 260,806 ) $ 4.42 Unvested as of September 30, 2024 1,545,791 $ 4.07 2021 Employee Stock Purchase Plan Under the Company's 2021 Employee Stock Purchase Plan (the 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 for a period of ten years 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 may determine. As of September 30, 2024, 1,767,746 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. For the nine months ended September 30, 2024 and 2023, 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 condensed statements of operations and comprehensive loss: Three Months Ended Nine Months Ended 2024 2023 2024 2023 Research and development $ 2,048 $ 1,861 $ 6,283 $ 5,204 General and administrative 1,859 2,154 6,459 6,156 Total stock-based compensation $ 3,907 $ 4,015 $ 12,742 $ 11,360

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2024
Line of Credit Facility [Abstract]
Debt Disclosure [Text Block]	6. Term Loan Loan Agreement On August 6, 2024, the Company entered into the Loan Agreement with SVB. Pursuant to the terms of the Loan Agreement, term loans in an aggregate principal amount of up to $ 45 million may be made under multiple tranches. The tranches can be drawn as follows: the first tranche of up to $ 15.0 million became available at the closing date through June 30, 2025; the second tranche of $ 5 million became available in October 2024 upon the achievement of a clinical milestone and is available through December 31, 2025. The third tranche of $ 2.5 million is available until December 31, 2025, subject to the achievement of certain clinical milestones; the fourth tranche of $ 2.5 million is available through December 31, 2025, subject to the achievement of a clinical milestone or satisfaction of certain capitalization requirements; and the final tranche of $ 20.0 million is available through July 31, 2026, on such terms as may be agreed by the parties and subject to approval by SVB's credit committee. With the exception of the final tranche, and subject to achievement of the applicable milestones and other requirements with respect to each tranche, draw downs are at the Company's election. As of September 30, 2024, the Company has no t drawn any funds under the Loan Agreement. Interest will accrue on the term loan advances at a rate per annum that is equal to the greater of 8.50 % and the prime rate and will be payable monthly in arrears. Principal payments on any term loan advances that are borrowed would commence on January 1, 2026 , subject to extension to July 1, 2026 , upon the satisfaction of certain milestones. As security for its obligations under the Loan Agreement, the Company granted SVB a security interest in substantially all of the assets of the Company, other than its intellectual property.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Stockholders' Equity	7. Stockholders' Equity Lender Warrant In connection with the Loan Agreement, the Company issued to SVB a warrant to purchase up to 171,848 shares of our common stock (the Lender Warrant). The Lender Warrant became exercisable for 73,649 shares upon closing (the Initial Lender Warrant), which represented 0.075 % of the Company's common stock and common stock equivalents outstanding as of the day before the closing, on a fully-diluted basis, at an exercise price of $ 2.55 per share. The Initial Lender Warrant was classified as equity and its fair value was recorded in the stockholders’ equity section of the balance sheet. The Lender Warrant will become exercisable for up to an additional 98,199 shares pro-rated based on amounts actually advanced for the various tranches under the Loan Agreement (the Remaining Lender Warrant). The Remaining Lender Warrant under the Loan Agreement is considered an outstanding instrument upon closing of the Loan Agreement for accounting purposes. In accordance with Accounting Standards Codification (ASC) 815-40, Derivatives and Hedging - Contracts in Entity's Own Equity , the Remaining Lender Warrant is recognized at its fair value as a warrant liability given the variable settlement amount of the warrant shares and included in other non-current liabilities within the condensed balance sheets. The Lender Warrant expires on August 6, 2034 . “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 September 30, 2024, the Company may issue and sell up to approximately $ 71.0 million in additional shares of its common stock under the ATM. Follow-On Offering 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 $ 46.8 million, after deducting underwriting discounts and commissions of approximately $ 3.0 million and offering expenses of $ 0.2 million. As of September 30, 2024, total shares of common stock reserved for issuance, on an as-if converted basis, are as follows: September 30, Outstanding stock options and awards 11,146,572 Outstanding pre-funded warrants 7,104,853 Outstanding Lender Warrant 171,848 Shares available for further issuance under the 2024 Inducement Equity Incentive Plan 1,200,000 Shares available for further issuance under the 2021 Equity Incentive Plan 1,355,277 Shares available for further issuance under the 2021 Employee Stock Purchase Plan 1,767,746 Total 22,746,296

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. 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: September 30, 2024 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Cash equivalents Level 1 $ 31 $ — $ — $ 31 Money market funds Level 1 6,247 — — 6,247 Marketable securities: U.S. treasuries Level 1 50,299 53 ( 7 ) 50,345 Commercial paper Level 2 5,901 11 — 5,912 Government agencies bonds Level 2 14,962 21 ( 2 ) 14,981 Total financial assets $ 77,440 $ 85 $ ( 9 ) $ 77,516 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 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. To date, 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 September 30, 2024, the fair value of available-for-sale marketable securities was $ 71.2 million, all of which had remaining maturities of less than one year . The Company's financial liability measured at fair value on a recurring basis consists of the Remaining Lender Warrant issued in connection with the Loan Agreement (see Note 7). The fair value of the warrant liability was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The Company utilized the Black-Scholes option valuation model to fair value the warrant liability. The fair value is estimated using the Black-Scholes option-pricing model and adjusted for the likelihood of draw downs. The expected term is based on the remaining contractual term of the warrant. The Company estimates its expected stock volatility based on the historical volatility of a set of peer companies, which are publicly traded, and expects to continue to do so until it has adequate historical data regarding the volatility of its own publicly-traded stock price. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of measurement for time periods approximately equal to the expected term of the Lender Warrant. The Company uses an expected dividend yield of zero based on the fact that the Company has never paid cash dividends and does not expect to pay cash dividends in the foreseeable future. The warrant liability is subject to re-measurement at each balance sheet date, and any change in fair value is recognized as a gain or loss in our statement of operations and comprehensive loss. During the three and nine months ended September 30, 2024, the fair value of the warrant liability and its change were not material. 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.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes For the nine months ended September 30, 2024 and 2023, the Company did no t record any income tax expense or benefit. The Company has recorded a full valuation allowance against its U.S. federal and state deferred tax assets as the Company believes it is more likely than not that the benefit will not be realized.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	10. 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 outstanding pre-funded warrants. The following potentially dilutive securities were not included in the calculation of diluted net loss per share as of the periods presented because the effect would have been anti-dilutive: September 30, 2024 2023 Outstanding stock options and restricted stock units 11,146,572 9,319,127 Outstanding Lender Warrant 171,848 — Total 11,318,420 9,319,127

Workforce Reduction

Workforce Reduction	9 Months Ended
	Sep. 30, 2024
Restructuring and Related Activities [Abstract]
Workforce Reduction	11. Workforce Reduction On May 14, 2024, the Company announced cost containment measures, including a committed plan to reduce its workforce (the Workforce Reduction) by approximately 22 %. The cost containment measures align with the Company's focus on generating data from its clinical-stage gene therapy programs. The Workforce Reduction was completed as of September 30, 2024. During the nine-months ended September 30, 2024, the Company recognized $ 1.4 million of aggregate charges, primarily related to employee cash severance and continuing health insurance benefits.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and follow the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. The interim condensed balance sheet as of September 30, 2024, the interim condensed statements of operations and comprehensive loss, stockholders’ equity and cash flows for the nine months ended September 30, 2024 and 2023 are unaudited. These unaudited interim condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and reflect all adjustments that are necessary for the fair statement of the Company’s financial position, results of operations and cash flows for the interim periods presented. The condensed results of operations for the nine months ended September 30, 2024, are not necessarily indicative of the results to be expected for the full year or for any other future annual or interim period. The condensed balance sheet as of December 31, 2023, included herein was derived from the audited financial statements as of that date. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and the related notes thereto for the year ended December 31, 2023, included in Company’s Annual Report on Form 10-K, filed with the SEC on March 18, 2024.
Use of Estimates	Use of Estimates The preparation of condensed 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 condensed 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, 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.
Recently Issued Accounting Pronouncements Note Yet Adopted	Recently Issued Accounting Pronouncements Not Yet Adopted In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (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, provides new segment disclosure requirements for entities with a single reportable segment, and contains other disclosure requirements. ASU 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The Company is evaluating the impact of this standard on its financial statements and related disclosures. 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.

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consists of the following: September 30, December 31, (In thousands) Leasehold improvements $ 25,728 $ 25,608 Laboratory equipment 20,201 19,973 Manufacturing equipment 17,716 17,716 Construction in progress 2,150 1,730 Computer equipment and software 1,664 1,614 Furniture and fixtures 981 976 Total property and equipment $ 68,440 $ 67,617 Less: accumulated depreciation and amortization ( 30,687 ) ( 24,340 ) Total property and equipment, net $ 37,753 $ 43,277
Summary of Accrued and Other Current Liabilities	Accrued and Other Current Liabilities Accrued and other current liabilities consist of the following: September 30, December 31, (In thousands) Accrued compensation and related expenses $ 4,735 $ 8,700 Accrued research and development expenses 1,566 2,583 Accrued professional services 389 743 Accrued taxes 202 280 Accrued facility management services — 185 Other current liabilities 435 293 Total accrued and other current liabilities $ 7,327 $ 12,784
Summary of Prepaid Expenses and Other Current Assets	Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: September 30, December 31, (In thousands) Prepaid expenses $ 4,458 $ 5,783 Other current assets 1,403 1,157 Total prepaid expenses and other current assets $ 5,861 $ 6,940

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Summary of Operating Lease Activity	Information related to operating lease activity during the three and nine months ended September 30, 2024 was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 (In thousands) Operating lease cost $ 1,356 $ 1,090 $ 3,506 $ 3,271 Variable lease cost 377 324 1,079 919 Short-term lease cost — — — 5 Total lease cost $ 1,733 $ 1,414 $ 4,585 $ 4,195 Operating lease right-of-use assets obtained in exchange for lease obligations $ 5,302 $ — Cash paid for amounts included in the measurement of lease liabilities $ 4,039 $ 4,000
Summary of Future Minimum Lease Payments Under Operating Lease	Future minimum lease payments under the Company’s operating leases as of September 30, 2024 were as follows: Amount (In thousands) 2024 (remaining 3 months) $ 1,238 2025 3,861 2026 3,864 2027 3,775 2028 1,471 Thereafter 4,006 Total undiscounted future minimum lease payments $ 18,215 Imputed interest ( 3,677 ) Total operating lease liabilities $ 14,538

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity: Shares Weighted- (in dollars) Outstanding as of December 31, 2023 8,343,434 $ 7.47 Granted 2,470,100 $ 5.13 Exercised ( 32,195 ) $ 1.69 Cancelled ( 1,180,558 ) $ 8.21 Outstanding as of September 30, 2024 9,600,781 $ 6.80
Summary of Fair Value of Stock Option Awards	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: Three Months Ended Nine Months Ended 2024 2023 2024 2023 Expected term (in years) N/A 6.1 6.0 – 6.1 5.5 – 6.1 Expected volatility N/A 94 % 92 % – 93 % 94 % – 95 % Risk-free interest rate N/A 4.0 % – 4.4 % 3.9 % – 4.5 % 3.4 % – 4.4 % Expected dividend yield N/A — % — % — % N/A - not applicable as no stock option awards were granted in the period presented.
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 (in dollars) Unvested as of December 31, 2023 1,088,276 $ 3.34 Granted 1,314,865 $ 4.52 Vested ( 596,544 ) $ 3.59 Forfeited ( 260,806 ) $ 4.42 Unvested as of September 30, 2024 1,545,791 $ 4.07
Summary of Stock-based Compensation	The following table summarizes stock-based compensation recognized in the Company’s condensed statements of operations and comprehensive loss: Three Months Ended Nine Months Ended 2024 2023 2024 2023 Research and development $ 2,048 $ 1,861 $ 6,283 $ 5,204 General and administrative 1,859 2,154 6,459 6,156 Total stock-based compensation $ 3,907 $ 4,015 $ 12,742 $ 11,360

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	As of September 30, 2024, total shares of common stock reserved for issuance, on an as-if converted basis, are as follows: September 30, Outstanding stock options and awards 11,146,572 Outstanding pre-funded warrants 7,104,853 Outstanding Lender Warrant 171,848 Shares available for further issuance under the 2024 Inducement Equity Incentive Plan 1,200,000 Shares available for further issuance under the 2021 Equity Incentive Plan 1,355,277 Shares available for further issuance under the 2021 Employee Stock Purchase Plan 1,767,746 Total 22,746,296

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
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: September 30, 2024 Valuation Amortized Unrealized Unrealized Fair Value (In thousands) Assets: Cash equivalents: Cash equivalents Level 1 $ 31 $ — $ — $ 31 Money market funds Level 1 6,247 — — 6,247 Marketable securities: U.S. treasuries Level 1 50,299 53 ( 7 ) 50,345 Commercial paper Level 2 5,901 11 — 5,912 Government agencies bonds Level 2 14,962 21 ( 2 ) 14,981 Total financial assets $ 77,440 $ 85 $ ( 9 ) $ 77,516 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

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following potentially dilutive securities were not included in the calculation of diluted net loss per share as of the periods presented because the effect would have been anti-dilutive: September 30, 2024 2023 Outstanding stock options and restricted stock units 11,146,572 9,319,127 Outstanding Lender Warrant 171,848 — Total 11,318,420 9,319,127

Organization and Description _2

Organization and Description of the Business - Additional Information (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Aug. 06, 2024	May 14, 2024	Dec. 31, 2023
Organization And Description Of Business [Line Items]
Accumulated deficit	$ (490,575,000)						$ (490,575,000)				$ (403,282,000)
Net loss	(25,634,000)	$ (29,431,000)	$ (32,228,000)	$ (29,143,000)	$ (33,269,000)	$ (31,737,000)	(87,293,000)	$ (94,149,000)
Cash, cash equivalents and investments in marketable securities	$ 79,500,000						$ 79,500,000
Workforce Reduction
Organization And Description Of Business [Line Items]
Percentage of reduction in workforce										22%
Estimates aggregate charges										$ 1,400,000
Silicon Valley Bank Loan Agreement
Organization And Description Of Business [Line Items]
Current loan amount available									$ 20,000,000
Silicon Valley Bank Loan Agreement | Maximum
Organization And Description Of Business [Line Items]
Additional amount available upon satisfaction of certain milestones									5,000,000
Remaining amount available									$ 20,000,000

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Total property and equipment	$ 68,440	$ 67,617
Less: accumulated depreciation and amortization	(30,687)	(24,340)
Total property and equipment, net	37,753	43,277
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	25,728	25,608
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	20,201	19,973
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	17,716	17,716
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	2,150	1,730
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment	1,664	1,614
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 981	$ 976

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 2.1	$ 2.2	$ 6.4	$ 6.5

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related expenses	$ 4,735	$ 8,700
Accrued research and development expenses	1,566	2,583
Accrued professional services	389	743
Accrued taxes	202	280
Accrued facility management services	0	185
Other current liabilities	435	293
Total accrued and other current liabilities	$ 7,327	$ 12,784

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Prepaid expenses	$ 4,458	$ 5,783
Other current assets	1,403	1,157
Total prepaid expenses and other current assets	$ 5,861	$ 6,940

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	1 Months Ended						9 Months Ended
	Jun. 30, 2024 Option	Oct. 31, 2023	May 31, 2022	Nov. 30, 2021	Feb. 28, 2021 RenewalOption	Dec. 31, 2016	Sep. 30, 2024	Dec. 31, 2023
Commitments And Contingencies [Line Items]
Weighted-average remaining lease term							4 years 10 months 24 days	5 years 1 month 6 days
Weighted-average discount rate							8.90%	9.30%
Union City, California
Commitments And Contingencies [Line Items]
Number of lease renewal term | RenewalOption					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 initial expiration month and year						2025-05
Lease renewal term						5 years
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Lease, option to extend							In June 2024, the Company amended the lease to extend the term to November 2027
Lease expiration month and year, end	2027-11
Number of option remaining to extend the lease term | Option	1
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	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,356	$ 1,090	$ 3,506	$ 3,271
Variable lease cost	377	324	1,079	919
Short-term lease cost	0	0	0	5
Total lease cost	$ 1,733	$ 1,414	4,585	4,195
Operating lease right-of-use assets obtained in exchange for lease obligations			5,302	0
Cash paid for amounts included in the measurement of lease liabilities			$ 4,039	$ 4,000

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Future Minimum Lease Payments Under Operating Leases (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024 (remaining 3 months)	$ 1,238
2025	3,861
2026	3,864
2027	3,775
2028	1,471
Thereafter	4,006
Total undiscounted future minimum lease payments	18,215
Imputed interest	(3,677)
Total operating lease liabilities	$ 14,538

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jul. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for issuance	22,746,296		22,746,296
Contractual term of stock option awards			10 years
Vesting period			4 years
Stock-based compensation	$ 3,907,000	$ 4,015,000	$ 12,742,000	$ 11,360,000
Restricted Stock | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period			2 years
Restricted Stock | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period			4 years
2021 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for issuance	1,767,746		1,767,746		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%
Common stock shares available for issuance period			10 years
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
Offering 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		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	1,355,277		1,355,277
Inducement Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares reserved and available for grant	1,200,000		1,200,000
2024 Inducement Equity Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock reserved for issuance	1,200,000		1,200,000
Number of shares issued under the Inducement plan			0

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2021 Equity Incentive Plan	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares, Outstanding Beginning Balance | shares	8,343,434
Granted | shares	2,470,100
Exercised | shares	(32,195)
Cancelled | shares	(1,180,558)
Shares, Outstanding Ending Balance | shares	9,600,781
Weighted-Average Exercise Price Per Share, Outstanding Beginning Balance | $ / shares	$ 7.47
Granted | $ / shares	5.13
Exercised | $ / shares	1.69
Cancelled | $ / shares	8.21
Weighted-Average Exercise Price Per Share, Outstanding Ending Balance | $ / shares	$ 6.8

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Fair Value of Stock Option Awards (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days
Expected volatility	94%
Expected volatility, minimum		92%	94%
Expected volatility, maximum		93%	95%
Risk-free interest rate, minimum	4%	3.90%	3.40%
Risk free interest rate, maximum	4.40%	4.50%	4.40%
Expected dividend yield	0%	0%	0%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)		6 years	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	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Number of Shares
Unvested as of December 31, 2023 | shares	1,088,276
Granted | shares	1,314,865
Vested | shares	(596,544)
Forfeited | shares	(260,806)
Unvested as of September 30, 2024 | shares	1,545,791
Weighted Average Grant Date Fair Value per Share
Unvested as of December 31, 2023 | $ / shares	$ 3.34
Granted | $ / shares	4.52
Vested | $ / shares	3.59
Forfeited | $ / shares	4.42
Unvested as of September 30, 2024 | $ / shares	$ 4.07

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation	$ 3,907	$ 4,015	$ 12,742	$ 11,360
Research and Development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation	2,048	1,861	6,283	5,204
General and Administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation	$ 1,859	$ 2,154	$ 6,459	$ 6,156

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - Silicon Valley Bank Loan Agreement - USD ($) $ in Millions	Aug. 06, 2024	Sep. 30, 2024
Line of Credit Facility [Line Items]
Funds under loan agreement		$ 0
Maximum borrowing capacity of term loans	$ 45
Interest Rate During Period	8.50%
Commence Date	Jan. 01, 2026
Extension Date	Jul. 01, 2026
First Tranche
Line of Credit Facility [Line Items]
Borrowing capacity of term loans	$ 15
Second Tranche
Line of Credit Facility [Line Items]
Borrowing capacity of term loans	5
Third Tranche
Line of Credit Facility [Line Items]
Borrowing capacity of term loans	2.5
Fourth Tranche
Line of Credit Facility [Line Items]
Borrowing capacity of term loans	2.5
Final Tranche
Line of Credit Facility [Line Items]
Borrowing capacity of term loans	$ 20

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended
	Feb. 12, 2024	Aug. 10, 2022	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024
Class of Stock [Line Items]
Proceeds from issuance of common stock at the market			$ 0	$ 3,868
Lender Warrant | Silicon Valley Bank Loan Agreement
Class of Stock [Line Items]
Number of share exercisable					73,649
Warrant issued to purchase shares of common stock					171,848
Warrant exercisable percentage					0.075%
Warrants expires date			Aug. 06, 2034
Warrants, exercise price					$ 2.55
Lender Warrant | Maximum | Silicon Valley Bank Loan Agreement
Class of Stock [Line Items]
Additional warrants exercisable			98,199
Follow On Offering
Class of Stock [Line Items]
Underwriting Discounts And Commissions	$ 3,000
Offering Expenses	200
Proceeds from issuance of common stock at the market	$ 46,800
Number of common shares	8,888,890
Common stock, per share	$ 4.50
Follow On Offering | Pre Funded Warrant
Class of Stock [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
Common Stock | At-the-Market Equity Offering
Class of Stock [Line Items]
Maximum aggregate offering price		$ 75,000
Maximum additional shares issuable			$ 71,000

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Common Stock Reserved for Issuance (Details)	Sep. 30, 2024 shares
Class Of Stock [Line Items]
Common stock reserved for issuance	22,746,296
Outstanding Pre-Funded Warrants
Class Of Stock [Line Items]
Common stock reserved for issuance	7,104,853
Outstanding Lender Warrant
Class Of Stock [Line Items]
Common stock reserved for issuance	171,848
Outstanding Stock Options and Awards
Class Of Stock [Line Items]
Common stock reserved for issuance	11,146,572
Shares Available for Further Issuance under the 2024 Inducement Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,200,000
Shares Available for Further Issuance under the 2021 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,355,277
Shares Available for Further Issuance under the 2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,767,746

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 77,440	$ 104,026
Unrealized Gain	85	11
Unrealized Loss	(9)	(117)
Fair Value	77,516	103,920
Cash Equivalents | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	31
Fair Value	31
Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	6,247	91
Fair Value	6,247	91
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
Unrealized Loss		(18)
Fair Value		34,883
Government Agencies Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		6,389
Unrealized Gain		1
Fair Value		6,390
U.S. Treasuries | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	50,299	16,182
Unrealized Gain	53	4
Unrealized Loss	(7)	(15)
Fair Value	50,345	16,171
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	5,901	2,971
Unrealized Gain	11
Unrealized Loss		(2)
Fair Value	5,912	2,969
Government Agencies Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	14,962	39,897
Unrealized Gain	21	6
Unrealized Loss	(2)	(82)
Fair Value	$ 14,981	$ 39,821

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charges on marketable securities related to other-than-temporary	$ 0
Available-for-sale marketable securities	77,516	$ 103,920
Marketable Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale marketable securities	$ 71,200
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale marketable securities contractual maturities term	1 year

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0

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	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
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	11,318,420	9,319,127
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	11,146,572	9,319,127
Outstanding Lender Warrant
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	171,848

Workforce Reduction (Additional

Workforce Reduction (Additional Information) (Details) - Workforce Reduction $ in Millions	May 14, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Percentage of reduction in workforce	22%
Estimates aggregate charges	$ 1.4

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - Silicon Valley Bank Loan Agreement	Aug. 06, 2024 USD ($)
Subsequent Event [Line Items]
Current loan amount available	$ 20,000,000
Maximum
Subsequent Event [Line Items]
Additional amount available upon satisfaction of certain milestones	5,000,000
Remaining amount available	$ 20,000,000