Adicet Bio (ACET) 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	Nov. 04, 2024
Cover [Abstract]
Entity Incorporation, State or Country Code	DE
Entity Common Stock, Shares Outstanding		82,400,960
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2024
Entity Registrant Name	Adicet Bio, Inc.
Entity Central Index Key	0001720580
Trading Symbol	ACET
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-38359
Entity Tax Identification Number	81-3305277
Entity Address, Address Line One	131 Dartmouth Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	650
Local Phone Number	503-9095
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Document Quarterly Report	true
Document Transition Report	false

Consolidated Balance Sheets (un

Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 105,482	$ 159,711
Short-term investments in treasury securities	96,583	0
Prepaid expenses and other current assets	4,251	2,561
Total current assets	206,316	162,272
Property and equipment, net	24,088	26,777
Operating lease right-of-use asset	15,050	17,424
Other non-current assets	508	822
Total assets	245,962	207,295
Current liabilities:
Accounts payable	2,500	2,625
Accrued and other current liabilities	13,616	13,441
Operating lease liability	3,278	3,221
Total current liabilities	19,394	19,287
Operating lease liability, net of current portion	14,921	17,703
Other non-current liabilities	116	130
Total liabilities	34,431	37,120
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized as of September 30, 2024 and December 31, 2023, respectively; none issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	0	0
Common stock, $0.0001 par value, 300,000,000 and 150,000,000 shares authorized as of September 30, 2024 and December 31, 2023, respectively; 82,400,960 and 43,270,386 shares issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	8	4
Additional paid-in capital	680,569	550,943
Accumulated deficit	(469,167)	(380,772)
Accumulated other comprehensive income	121	0
Total stockholders’ equity	211,531	170,175
Total liabilities and stockholders’ equity	$ 245,962	$ 207,295

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) (unaudited) - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock price per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	150,000,000
Common stock, shares issued	82,400,960	43,270,386
Common stock, shares outstanding	82,400,960	43,270,386
Preferred Stock, par value	$ 0.0001	$ 0.0001
Preferred stock shares authorized	10,000,000	10,000,000
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0

Consolidated Statements of Oper

Consolidated 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	$ 26,253	$ 26,167	$ 76,050	$ 81,284
General and administrative	6,900	6,633	20,822	19,726
Goodwill impairment	0	19,462	0	19,462
Total operating expenses	33,153	52,262	96,872	120,472
Loss from operations	(33,153)	(52,262)	(96,872)	(120,472)
Interest income	2,730	2,520	8,647	7,800
Interest expense	(1)	(1)	(3)	(25)
Other expense, net	(54)	(142)	(167)	(472)
Loss before income tax provision	(30,478)	(49,885)	(88,395)	(113,169)
Income tax provision	0	0	0	0
Net loss	$ (30,478)	$ (49,885)	$ (88,395)	$ (113,169)
Net loss per share, basic	$ (0.34)	$ (1.16)	$ (1.02)	$ (2.63)
Net loss per share, diluted	$ (0.34)	$ (1.16)	$ (1.02)	$ (2.63)
Weighted-average common shares used in computing net loss per share, diluted	90,846,293	42,980,641	86,865,285	43,001,901
Weighted-average common shares used in computing net loss per share, basic	90,846,293	42,980,641	86,865,285	43,001,901
Other comprehensive income
Unrealized gain on treasury securities, net of tax	$ 121	$ 0	$ 121	$ 0
Total other comprehensive income	121	0	121	0
Comprehensive loss	$ (30,357)	$ (49,885)	$ (88,274)	$ (113,169)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Pain In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2022	$ 292,338	$ 4	$ 530,448	$ (238,114)
Balance, shares at Dec. 31, 2022		42,954,820
Issuance of common stock upon exercise of stock options	3		3
Issuance of common stock upon exercise of stock options, shares		713
Issuance of common stock upon vesting of restricted stock, shares		3,205
Shares withheld for taxes	(10)		(10)
Shares withheld for taxes, shares		(1,307)
Stock-based compensation expense	4,765		4,765
Net Income (Loss)	(30,881)			(30,881)
Balance at Mar. 31, 2023	266,215	$ 4	535,206	(268,995)
Balance, shares at Mar. 31, 2023		42,957,431
Balance at Dec. 31, 2022	292,338	$ 4	530,448	(238,114)
Balance, shares at Dec. 31, 2022		42,954,820
Issuance of common stock upon vesting of restricted stock, shares		66,750
Net Income (Loss)	(113,169)
Balance at Sep. 30, 2023	194,677	$ 4	545,956	(351,283)
Balance, shares at Sep. 30, 2023		43,107,921
Balance at Mar. 31, 2023	266,215	$ 4	535,206	(268,995)
Balance, shares at Mar. 31, 2023		42,957,431
Issuance of common stock upon exercise of stock options	1		1
Issuance of common stock upon exercise of stock options, shares		233
Purchase of common stock under Employee Stock Purchase Plan	225		225
Purchase of common stock under Employee Stock Purchase Plan Shares		108,494
Stock-based compensation expense	5,023		5,023
Net Income (Loss)	(32,403)			(32,403)
Balance at Jun. 30, 2023	239,061	$ 4	540,455	(301,398)
Balance, shares at Jun. 30, 2023		43,066,158
Shares withheld for taxes	(59)		(59)
Shares withheld for taxes, shares		(24,987)
Stock-based compensation expense	5,560		5,560
Net Income (Loss)	(49,885)			(49,885)
Balance at Sep. 30, 2023	194,677	$ 4	545,956	(351,283)
Balance, shares at Sep. 30, 2023		43,107,921
Balance at Dec. 31, 2023	170,175	$ 4	550,943	(380,772)
Balance, shares at Dec. 31, 2023		43,270,386
Issuance of common stock upon exercise of stock options	189		189
Issuance of common stock upon exercise of stock options, shares		88,283
Issuance of common stock upon vesting of restricted stock, shares		148,980
Shares withheld for taxes	(141)		(141)
Shares withheld for taxes, shares		(67,813)
Issuance of common stock pursuant to at-the-market offering, net of issuance costs of $0.6 million, Amount	19,266	$ 1	19,265
Issuance of common stock pursuant to at-the-market offering, net of issuance costs of $0.6 million, Share		6,350,000
Issuance of common stock and pre-funded warrants pursuant to underwritten public offering, net of issuance costs of $6.3 million, Amount	91,652	$ 3	91,649
Issuance of common stock and pre-funded warrants pursuant to underwritten public offering, net of issuance costs of $6.3 million, Share		32,379,667
Stock-based compensation expense	5,679		5,679
Net Income (Loss)	(28,016)			(28,016)
Balance at Mar. 31, 2024	258,804	$ 8	667,584	(408,788)
Balance, shares at Mar. 31, 2024		82,169,503
Balance at Dec. 31, 2023	$ 170,175	$ 4	550,943	(380,772)
Balance, shares at Dec. 31, 2023		43,270,386
Issuance of common stock upon exercise of stock options, shares	92,283
Net Income (Loss)	$ (88,395)
Balance at Sep. 30, 2024	211,531	$ 8	680,569	(469,167)	$ 121
Balance, shares at Sep. 30, 2024		82,400,960
Balance at Mar. 31, 2024	258,804	$ 8	667,584	(408,788)
Balance, shares at Mar. 31, 2024		82,169,503
Issuance of common stock upon exercise of stock options	6		6
Issuance of common stock upon exercise of stock options, shares		4,000
Issuance of common stock upon vesting of restricted stock, shares		35,400
Purchase of common stock under Employee Stock Purchase Plan	198		198
Purchase of common stock under Employee Stock Purchase Plan Shares		192,057
Stock-based compensation expense	6,004		6,004
Net Income (Loss)	(29,901)			(29,901)
Balance at Jun. 30, 2024	235,111	$ 8	673,792	(438,689)
Balance, shares at Jun. 30, 2024		82,400,960
Other comprehensive income	121			121
Stock-based compensation expense	6,777		6,777
Net Income (Loss)	(30,478)			(30,478)
Balance at Sep. 30, 2024	$ 211,531	$ 8	$ 680,569	$ (469,167)	$ 121
Balance, shares at Sep. 30, 2024		82,400,960

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
Statement of Stockholders' Equity [Abstract]
Stock issuance cost	$ 0.6
Adjustments to Additional Paid in Capital, Warrant Issued	$ 6.3

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities
Net loss	$ (88,395)	$ (113,169)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	4,845	4,409
Noncash lease expense	2,375	2,083
Stock-based compensation expense	18,460	15,348
Net amortization of premiums and accretion discounts on investments	(282)	0
Goodwill impairment	0	19,462
Amortization of deferred debt issuance costs	39	29
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,690)	756
Other non-current assets	277	265
Accounts payable	(47)	(223)
Operating lease liabilities	(2,726)	773
Accrued and other current and non-current liabilities	(1,133)	36
Net cash used in operating activities	(68,277)	(70,231)
Cash flows from investing activities
Purchases of short-term treasury securities	(96,180)	0
Purchases of property and equipment	(942)	(4,328)
Net cash used in investing activities	(97,122)	(4,328)
Cash flows from financing activities
Proceeds from issuance of common stock pursuant to at-the-market offering, net of issuance costs	19,266	0
Proceeds from issuance of common stock and pre-funded warrants pursuant to underwritten public offering, net of issuance costs	91,652	0
Proceeds from exercise of stock options	195	4
Proceeds from Employee Stock Purchase Plan	198	225
Taxes withheld and paid related to net share settlement of equity awards	(141)	(69)
Net cash provided by financing activities	111,170	160
Net change in cash and cash equivalents	(54,229)	(74,399)
Cash and cash equivalents at the beginning of period	159,711	257,656
Cash and cash equivalents, at the end of period	105,482	183,257
Supplemental disclosures of noncash investing and financing activities
Purchases of property and equipment included in accounts payable and accrued expenses	$ 1,493	$ 105

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)	$ (30,478)	$ (29,901)	$ (28,016)	$ (49,885)	$ (32,403)	$ (30,881)	$ (88,395)	$ (113,169)

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 Nature of Busi

Organization and Nature of Business	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Business	1. Organization and Nature of the Business Adicet Bio, Inc. (formerly resTORbio, Inc. (resTORbio), together with its subsidiaries, the Company) is a clinical stage biotechnology company discovering and developing allogeneic gamma delta T cell therapies for autoimmune diseases and cancer. The Company is advancing a pipeline of “off-the-shelf” gamma delta T cells, engineered with chimeric antigen receptors (CARs), to facilitate durable activity in patients. Adicet Bio, Inc. (when referred to prior to the merger, Former Adicet) was incorporated in November 2014 in Delaware. On September 15, 2020, Former Adicet completed a merger (Merger) with resTORbio, pursuant to which Former Adicet merged with a wholly owned subsidiary of resTORbio in an all-stock transaction with Former Adicet surviving as a wholly owned subsidiary of resTORbio and changing its name to “Adicet Therapeutics, Inc.” (Adicet Therapeutics). In connection with the Merger, the Company changed its name from “resTORbio, Inc.” to “Adicet Bio, Inc.” The Company’s principal executive offices are located in Boston, Massachusetts. The Company also has offices in Redwood City, California. Adicet Bio Israel Ltd. (formerly Applied Immune Technologies Ltd.) (Adicet Israel) is a wholly owned subsidiary of the Company and is located in Haifa, Israel. Adicet Israel was founded in 2006. During 2019, the Company consolidated its operations, including research and development activities, in the United States and as a result, substantially reduced its operations in Israel. Adicet (Shanghai) Biotechnology Co., Ltd. (Adicet Shanghai) is a wholly owned subsidiary of Adicet Therapeutics and is located in Shanghai, China. Adicet Shanghai was founded in May 2024. In May 2024, the Company initiated research and development activities in China through a series of contractual agreements entered into and among Shanghai Adicet Biotechnology Co., Ltd., a variable interest entity (the Adicet VIE), Adicet Shanghai, and the shareholders of the Adicet VIE. The Company is the primary beneficiary of the Adicet VIE which is considered a consolidated entity under accounting principles generally accepted in the United States of America (U.S. GAAP). The Company consolidates the financial results of this entity into its consolidated financial statements in accordance with U.S. GAAP. Liquidity The Company has incurred significant net operating losses and negative cash flows from operations and has an accumulated deficit of $ 469.2 million as of September 30, 2024. The Company has historically financed its operations primarily through a collaboration and licensing arrangement, public and private placements of equity securities and debt, and cash received in the Merger with resTORbio. To date, none of the Company’s product candidates have been approved for sale and therefore the Company has not generated any revenue from product sales. Management expects operating losses and negative cash flows to continue for the foreseeable future, until such time, if ever, that it can generate significant sales of its product candidates currently in development. On March 12, 2021, the Company entered into a Capital On Demand™ Sales Agreement (the JonesTrading Sales Agreement) with JonesTrading Institutional Services LLC, as sales agent, to provide for the offering, issuance and sale of up to an aggregate amount of $ 75.0 million of shares of common stock from time to time in “at-the-market” (ATM) offerings. In August 2022, pursuant to the JonesTrading Sales Agreement and subject to the limitations thereof, the Company sold an aggregate of 2,611,723 shares of common stock at $ 17.23 per share resulting in net proceeds to the Company of $ 43.4 million after deducting sales agent commissions and expenses. In November 2022, the Company filed a new prospectus supplement to the 2021 Shelf Registration Statement for the offer and sale of up to $ 100.0 million of shares of common stock from time to time through the sales agent, which includes the $ 30.0 million of shares of common stock not sold under the original prospectus and up to an additional $ 70.0 million of shares of common stock (the JonesTrading ATM Program). In January 2024, the Company raised aggregate net proceeds of approximately $ 19.3 million through the JonesTrading ATM Program. In March 2024, the Company terminated the JonesTrading ATM Program. On January 22, 2024, Adicet entered into an Underwriting Agreement (the Underwriting Agreement) with Jefferies LLC (Jefferies) and Guggenheim Securities, LLC (the Underwriters) related to an underwritten public offering (the Offering) of 27,054,667 shares (the Shares) of common stock of the Company, par value $ 0.0001 per share (the Common Stock), and, in lieu of Common Stock to an investor, pre-funded warrants (the Pre-Funded Warrants) to purchase 8,445,333 shares of Common Stock (the Warrant Shares). The Shares were sold at a public offering price of $ 2.40 per share and the Pre-Funded Warrants were sold at a public offering price of $ 2.3999 per underlying share, which represents the per share public offering price of each share of common stock minus the $ 0.0001 per share exercise price for each pre-funded warrant. The purchase price paid by the Underwriters to the Company was $ 2.256 per Share and $ 2.2559 per Pre-Funded Warrant, representing a discount to the Underwriters of 6.0 %. In addition, the Company granted the Underwriters an option exercisable for 30 days from the date of the Underwriting Agreement to purchase, at the public offering price less underwriting discounts and commissions, up to an additional 5,325,000 shares of Common Stock. On January 23, 2024, the Underwriters exercised this option in full. The Company received net proceeds from the Offering, after deducting the underwriting discount and commissions and other estimated offering expenses, of approximately $ 91.7 million. The Company may receive nominal proceeds, if any, from the exercise of the Pre-Funded Warrants. In March 2024, the Company entered into an Open Market Sales Agreement SM (the Jefferies Sales Agreement) with Jefferies to sell shares of its Common Stock from time to time, through an ATM equity offering program under which Jefferies will act as sales agent or principal. As of September 30, 2024, no shares of common stock have been sold under the Jefferies Sales Agreement. The Company expects that its cash, cash equivalents and short-term investments in treasury securities, including the proceeds raised through the JonesTrading ATM Program and the Offering, will be sufficient to fund its forecasted operating expenses, capital expenditure requirements and debt service payments for at least the next twelve months from the issuance of these unaudited interim consolidated financial statements. All of the Company’s revenue to date has been generated from a collaboration and license agreement (the Regeneron Agreement) with Regeneron Pharmaceuticals, Inc, (Regeneron). The Company does not expect to generate any significant product revenue until it obtains regulatory approval of and commercializes any of the Company’s product candidates or enters into additional collaborative agreements with third parties, and it does not know when, or if, either will occur. The Company expects to continue to incur significant losses for the foreseeable future, and it expects the losses to increase as the Company continues the development of, and seeks regulatory approvals for, its product candidates and begins to commercialize any approved products. The Company is subject to all of the risks typically related to the development of new product candidates, including, but not limited to, raising additional capital, development by its competitors of new technological innovations, risk of failure in preclinical and clinical studies, safety and efficacy of its product candidates in clinical trials, the risk of relying on external parties such as contract research organizations (CROs) and contract development and manufacturing organizations (CDMOs), the regulatory approval process, market acceptance of the Company’s products once approved, lack of marketing and sales history, dependence on key personnel and protection of proprietary technology and it may encounter unforeseen expenses, difficulties, complications, delays, and other unknown factors that may adversely affect its business. Until such time as the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through the sale of equity, debt financings, collaborative or other arrangements with corporate or other sources of financing. Adequate funding may not be available to the Company on acceptable terms or at all. The Company’s failure to raise capital as and when needed could have a negative impact on its financial condition and the Company’s ability to pursue its business strategies. Although the Company continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

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 unaudited interim consolidated financial statements and related disclosures have been prepared in conformity with U.S. GAAP. Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, "Summary of Significant Accounting Policies," to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. There have been no material changes to the significant accounting policies during the nine months ended September 30, 2024 . Principles of Consolidation The Company assesses entities for consolidation based on the specific facts and circumstances surrounding that entity. The Company first considers whether an entity is considered a variable interest entity (VIE) and therefore whether to apply the consolidation guidance under the VIE model. Entities that do not qualify as VIEs are assessed for consolidation as voting interest entities under the voting interest model. An entity is considered to be a VIE if any of the following conditions exist: (i) the equity investment at risk is not sufficient to finance the activities of the entity without additional subordinated financial support, (ii) as a group, the holders of the equity investment at risk lack the power to direct the activities that most significantly impact the entity’s economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, and (iii) the voting rights of some holders of the equity investment at risk are disproportionate to their obligation to absorb losses or right to receive returns, and substantially all of the activities are conducted on behalf of the holder of equity investment at risk with disproportionately few voting rights. The Company consolidates all VIEs in which it is the primary beneficiary. An entity is determined to be the primary beneficiary if it holds a controlling financial interest in a VIE. The consolidation guidance requires an analysis to determine (i) whether an entity in which the Company holds a variable interest is a VIE and (ii) whether the Company’s involvement, through holding interest directly or indirectly in the entity or contractually through other variable interests, would give it a controlling financial interest. Performance of that analysis requires judgment. As described in Note 1, Shanghai Adicet Biotechnology Co., Ltd., has been identified as a VIE and the Company is the primary beneficiary. Refer to Note 15 for additional information and operating activities for the VIE as of September 30, 2024 . Unaudited Interim Financial Information The accompanying unaudited consolidated financial statements as of September 30, 2024, and for the three and nine months ended September 30, 2024, have been prepared by the Company, pursuant to the rules and regulations of the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2023. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s consolidated financial position as of September 30, 2024 and consolidated results of operations for the three and nine months ended September 30, 2024 and 2023 and consolidated cash flows for the nine months ended September 30, 2024 and 2023 have been made. The results of operations for the three and nine months ended September 30, 2024 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2024. Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash, cash equivalents and short-term investments in treasury securities. The Company’s cash and cash equivalents, as well as its short-term investments in treasury securities, are held at two financial institutions in the U.S., one financial institution in China and one financial institution in Israel and such amounts may, at times, exceed insured limits. The Company invests its cash equivalents in treasury securities and money market funds. The Company limits its credit risk associated with cash equivalents and short-term investments in treasury securities by placing them with banks and institutions it believes are highly creditworthy and in highly rated investments. The Company has not experienced any losses on its deposits of cash and cash equivalents or its short-term investments in treasury securities to date. Risks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical studies, clinical trials, and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance and reporting. The Company’s product candidates are still in development and, to date, none of the Company’s product candidates have been approved for sale and, therefore, the Company has not generated any revenue from product sales. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biotechnology companies. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Accounting Pronouncements Not Yet Adopted In September 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which enhances the transparency and usefulness of income tax disclosures. This amendment requires public issuers to disclose specific categories in the rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold (if the effect of those reconciling items is equal to or greater than 5 percent of the amount computed by multiplying pretax income, or loss, by the applicable statutory income tax rate. Additionally, this amendment requires issuers to disclose the amount of income taxes paid (net of refunds received) disaggregated by federal (national), state, and foreign taxes as well as the amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which income taxes paid (net of refunds received) is equal to or greater than 5 percent of total income taxes paid (net of refunds received). For SEC filers, this ASU is effective for fiscal years beginning after December 15, 2025. Early adoption is permitted. The Company is currently evaluating the impact the adoption that this ASU will have on its consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures , which enables investors to better understand an entity's overall performance and assists with assessing potential future cash flows. This amendment improves financial reporting by requiring disclosure of incremental segment information on an annual and interim basis for all public entities to enable investors to develop more decision-useful financial analyses. It is applicable to all public entities that are required to report segment information in accordance with Topic 280, Segment Reporting. For SEC filers, this ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact the adoption that this ASU will have on its consolidated financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company determines the fair value of financial and non-financial assets and liabilities using the fair value hierarchy which establishes three level of inputs that may be used to measure fair value, as follows: Level 1 — Observable inputs, such as quoted prices in active markets for identical assets or liabilities. Level 2 — Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 — Unobservable inputs which 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. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands): September 30, 2024 Level 1 Level 2 Level 3 Total Assets: Treasury securities (1) (3) $ 96,583 $ — $ — $ 96,583 Treasury securities (2) (3) $ 32,854 $ — $ — $ 32,854 Money market funds (2) (3) $ 28,849 $ — $ — $ 28,849 Total fair value of assets $ 158,286 $ — $ — $ 158,286 December 31, 2023 Level 1 Level 2 Level 3 Total Assets: Treasury securities (2) (3) $ 115,143 $ — $ — $ 115,143 Total fair value of assets $ 115,143 $ — $ — $ 115,143 (1) Included in short-term investments in treasury securities in the consolidated balance sheets. These securities have maturity dates of greater than three months, but less than twelve months from the date of purchase. (2) Included in cash and cash equivalents in the consolidated balance sheets. These securities have maturity dates of less than three months from the date of purchase. (3) Treasury securities and money market funds are included within Level 1 of the fair value hierarchy because they are actively traded and valued using quoted market prices.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Expenses and Other Current Assets	4. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, Prepayments to CROs and CDMOs $ 1,477 $ 53 Prepaid software subscription and licensing fees 664 582 Prepaid maintenance 544 373 Prepaid insurance 425 1,014 Prepaid employee benefits 306 — Interest receivable 210 — Prepaid professional services 82 82 Other prepaid expenses and current assets 543 457 Total prepaid expenses and other current assets $ 4,251 $ 2,561

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, net Property and equipment, net consisted of the following (in thousands): Useful life September 30, December 31, Leasehold improvements Lesser of useful life or lease term $ 26,663 $ 26,643 Laboratory equipment 3 13,695 13,165 Furniture and fixtures 3 951 951 Construction in progress — 1,868 265 Computer equipment 3 193 189 Software 3 411 411 43,781 41,624 Less: Accumulated depreciation and amortization ( 19,693 ) ( 14,847 ) Property and equipment, net $ 24,088 $ 26,777 Depreciation and amortization expense was $ 1.6 million and $ 1.6 million for the three months ended September 30, 2024 and 2023, respectively. Depreciation and amortization expense was $ 4.8 million and $ 4.4 million for the nine months ended September 30, 2024 and 2023, respectively.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	9 Months Ended
	Sep. 30, 2024
Payables and Accruals [Abstract]
Accrued and Other Current Liabilities	6. Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): September 30, December 31, Accrued compensation $ 6,103 $ 6,514 Accrued CDMO costs 4,810 5,679 Accrued professional services 506 625 Accrued other research and development expenses 1,685 354 Accrued CRO costs 489 257 Accrued other liabilities 23 12 Total accrued and other liabilities $ 13,616 $ 13,441

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2024
Term Loan [Abstract]
Term Loan	7. Term Loan On April 28, 2020, the Company entered into a Loan and Security Agreement (the Loan Agreement) as amended on July 8, 2020, September 14, 2020, September 15, 2020, October 21, 2021 (the 2021 Loan Amendment), December 2, 2022 (the 2022 Loan Amendment) and May 30, 2023 with Banc of California (formerly known as Pacific Western Bank) to finance leasehold improvements for the facilities in Redwood City, CA and other purposes permitted under the Loan Agreement. Under the 2021 Loan Amendment, Banc of California will provide one or more Term Loans (as defined in the 2021 Loan Amendment), as well as Non-Formula Ancillary Services which shall not exceed $ 5.5 million in the aggregate. Non-Formula Ancillary Services are defined as automated clearinghouse transactions, corporate credit card services, letters of credit, or other treasury management services. Per the terms of the Loan Agreement, the aggregate sum of the outstanding Term Loans and Non-Formula Ancillary Services shall at no time exceed $ 15.0 million, which each Term Loan to be in an amount of not less than $ 1.0 million. On March 13, 2023, the Company and Banc of California executed a letter agreeing that, notwithstanding the covenants included in the 2022 Loan Amendment, until June 30, 2023 (i) the Company and its subsidiaries will not be required to maintain the lesser of $ 200 million or seventy percent (70%) of its combined balances in demand deposit accounts, money market funds and/or insured cash sweep (ICS) accounts with Banc of California and (ii) the Company must maintain its combined balances at Banc of California or its affiliates, including Pacific Western Asset Management (the Letter). On May 30, 2023, the Company further amended its Loan Agreement with Banc of California (the 2023 Loan Amendment). Pursuant to the 2023 Loan Amendment, the Company must maintain the lesser of (i) $ 35.0 million or (ii) all of the Company’s combined balances in demand deposit accounts, money market accounts, and/or insured cash sweep accounts with Banc of California. If the Company’s total cash and investments drop to less than $ 35.0 million, the 2023 Loan Amendment permits the Company to maintain cash and/or investments in one or more accounts outside of Banc of California up to a total of $ 2.5 million. In April 2024, the Term Loan availability under the Loan Agreement expired. The Non-Formula Ancillary Services, which shall not exceed $ 5.5 million in the aggregate, remain available under the Loan Agreement as of the date of this Quarterly Report on Form 10-Q. As of September 30, 2024 , the Company had $ 3.2 million available under the Loan Agreement. Additionally, as of the date of this Quarterly Report on Form 10-Q, the Company was in compliance with such covenants as stated in the 2023 Loan Amendment and had no indebtedness outstanding under the Loan Agreement.

Third Party Agreements

Third Party Agreements	9 Months Ended
	Sep. 30, 2024
Revenue Recognition and Deferred Revenue [Abstract]
Third Party Agreements	8. Third Party Agreements Regeneron On July 29, 2016, the Company entered into a license and collaboration agreement with Regeneron, which was amended in April 2019, with such amendment becoming effective in connection with Regeneron’s investment in the Company’s Series B redeemable convertible preferred stock private placement transaction in July 2019 (as amended, the Regeneron Agreement). Financial Terms. The Company received a non-refundable upfront payment of $ 25.0 million from Regeneron upon execution of the Regeneron Agreement and an aggregate of $ 20.0 million of additional payments for research funding from Regeneron as of September 30, 2024 . In addition, Regeneron may have to pay the Company additional amounts in the future consisting of up to an aggregate of $ 80.0 million of option exercise fees, as specified in the Regeneron Agreement. Per the terms of the agreement, Regeneron must pay the Company high single digit royalties as a percentage of net sales for immune cell products (ICPs) to targets for which it has exclusive rights, and low single digit royalties as a percentage of net sales on any non-ICP product comprising a targeting moiety generated by the Company through the use of Regeneron’s proprietary mice. The Company must pay Regeneron mid-single to low double digit, but less than teens, of royalties as a percentage of net sales of ICPs to targets for which the Company has exercised exclusive rights, and low to mid-single digit of royalties as a percentage of net sales of targeting moieties generated from the Company’s license to use Regeneron’s proprietary mice. Royalties are payable until the longer of the expiration or invalidity of the licensed patent rights or twelve (12) years from first commercial sale. No royalties have been earned or paid under the Regeneron Agreement through September 30, 2024. On January 28, 2022, Regeneron exercised its option to license the exclusive, worldwide rights to ADI-002, an allogeneic gamma delta CAR T cell therapy directed against Glypican-3, pursuant to the Regeneron Agreement. In conjunction with the exercise of the option, Regeneron paid an exercise fee of $ 20.0 million to the Company on January 28, 2022, and the Company completed the transfer of the associated license rights to Regeneron during the first quarter of 2022. The $ 20.0 million option exercise fee, plus $ 5.0 million of revenue recognized relating to the combined performance obligation, resulted in an aggregate of $ 25.0 million recorded as revenue for the year ended December 31, 2022. The Company's obligations under the combined performance obligation were completed during the year ended December 31, 2022. Regeneron is responsible, at its sole cost, for all development, manufacturing and commercialization of ADI-002 and must pay the Company high single digit royalties as a percentage of any net sales of ADI-002 for a period commencing on the first commercial sale until the longer of (i) the expiration or invalidity of the licensed patent rights or (ii) a low double digit amount of years from first commercial sale. Twist Bioscience In March 2021, the Company entered into an Antibody Discovery Agreement (the Twist Agreement) with Twist Bioscience Corporation (Twist). Under the terms of the Twist Agreement, Twist will utilize its proprietary platform technology to assist the Company with the discovery of novel antibodies related to target antigens selected by the Company. The Company maintains the sole and exclusive rights to any program antibodies discovered under the Twist Agreement and has the right to patent, assign, license or transfer any work product under the agreement. Furthermore, the Company has the right to sublicense its rights to program antibodies to third parties. The Company may terminate the Twist Agreement at any time, with or without cause, upon a specified period advance written notice. Per the terms of the agreement, the Company will pay Twist an upfront, non-refundable project initiation fee, a technology access fee, as well as a project fee for each project entered into under the agreement. Additionally, the Company will pay fees for development and regulatory milestones in the tens of millions of dollars and low single digit royalties on net sales to Twist for programs initiated under the agreement. In November 2022, the Company entered into an amendment to the Twist Agreement (the Twist Amendment). The Twist Amendment updates the language associated with Twist's audit rights as well as the amounts associated with technology access fees. On a cumulative basis as of September 30, 2024 , the Company has incurred and expensed $ 1.0 million related to project initiation fees, technology access fees and projects fees as research and development expense related to this agreement.

Commitments and Contingences

Commitments and Contingences	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingences	9. Commitments and Contingencies Operating Leases The Company leases office and laboratory space in Redwood City, California, and Boston, Massachusetts. Redwood City In 2018, Adicet Therapeutics executed a non-cancelable lease agreement, as amended in 2022, pursuant to which the Company leases office and laboratory facility at 1000 Bridge Parkway and a portion of 1200 Bridge Parkway in Redwood City, California (the Redwood City Lease). On January 9, 2023, Adicet Therapeutics entered into a third lease amendment with Westport Office Park, LLC (the Third Amendment). The Third Amendment further amends the Redwood City Lease and increases the tenant improvement allowance as of January 1, 2023 by an additional $ 3.0 million. The Company fully utilized the allowance for the continued buildout of office and laboratory space at 1000 Bridge Parkway in 2023. Per the terms of this amendment, this additional allowance will be repaid through equal monthly payments of principal amortization and interest on a monthly basis over the term of the lease at an interest rate of eight percent ( 8 %) per annum. The Company received the allowance on February 21, 2023 and increased the operating lease liability accordingly. On August 7, 2023, Adicet Therapeutics entered into a fourth lease amendment with Westport Office Park, LLC (the Fourth Amendment). The Fourth Amendment amends the period over which the tenant improvement allowance received in the Third Amendment will be amortized and identifies the monthly amortization payable by the Company. On September 1, 2023, Adicet Therapeutics amended its letter of credit with Westport Office Park, LLC. The amendment reduced the amount of the letter of credit associated with 1000 Bridge Parkway by $ 2.1 million resulting in an updated letter of credit amount of $2.1 million. Boston In 2018, the Company entered into a lease agreement, as amended in 2019, for office space at 500 Boylston St, Boston, Massachusetts (500 Boylston Lease). Under the terms of the 500 Boylston Lease, the Company was permitted to assign, sublease or transfer this lease, with the consent of the landlord. On July 19, 2021, the Company entered into a sublease agreement with RFS OPCO LLC (Sublessee), whereby the Company agreed to sublease to Sublessee all of the 9,501 rentable square feet of 500 Boylston St. The expected undiscounted cash flows to be received from the sublease as of September 30, 2024 is as follows (in thousands): September 30, 2024 $ 180 2025 736 2026 438 2027 and thereafter — Total $ 1,354 Further, the Company remains liable for the remaining lease payments under the 500 Boylston Lease, totaling $ 1.2 million, which is included in the future minimum lease payments table below. The future minimum lease payments under all non-cancelable operating lease obligations as of September 30, 2024 were as follows (in thousands): September 30, 2024 $ 1,274 2025 4,662 2026 4,009 2027 3,714 2028 and thereafter 8,376 Total undiscounted lease payments 22,035 Less: imputed interest ( 3,836 ) Total operating lease liability 18,199 Less: current portion ( 3,278 ) Operating lease liability, net of current maturities $ 14,921 The following table presents the operating lease cost and information related to the operating lease right-of-use assets, net and operating lease liabilities for the quarter ended September 30, 2024 (in thousands): Three Months Ended September 30, 2024 Lease Cost Operating lease cost $ 1,140 Short-term lease cost 32 Sublease income ( 182 ) Total lease cost $ 991 Other Information Operating cash flows used for lease liabilities $ ( 2,726 ) Weighted-average remaining lease term - operating leases 5.1 Weighted-average discount rate - operating leases 7 % For the nine months ended September 30, 2024 , the Company recognized $ 3.4 million and less than $ 0.1 million in operating lease and short-term lease costs, respectively. Additionally, for the nine months ended September 30, 2024 , the Company recognized $ 0.6 million in sublease income.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Stockholders' Equity	10. Stockholders' Equity Common Stock The Company’s Restated Certificate of Incorporation, which became effective as of June 6, 2024, authorized the Company to issue 300,000,000 shares of common stock, par value $ 0.0001 per share, as of September 30, 2024. Common stockholders are entitled to dividends if and when declared by the board of directors of the Company subject to the prior rights of the preferred stockholders. As of September 30, 2024 , no dividends on common stock had been declared by the board of directors. The Company has the following shares of common stock reserved for future issuance: September 30, December 31, Stock options and restricted stock units available for future grant 2,302,470 2,473,485 Stock options issued and outstanding 15,698,630 9,383,105 Unvested restricted stock units 765,856 454,200 Common stock warrants issued and outstanding 8,445,333 — Total common stock reserved 27,212,289 12,310,790 On January 22, 2024, the Company entered into the Underwriting Agreement with Jefferies and Guggenheim Securities, LLC, as representatives of the Underwriters, related to the Offering of 32,379,667 shares of our common stock, which included 5,325,000 shares sold and issued upon the exercise in full by the Underwriters of their option to purchase additional shares of common stock, and, in lieu of common stock to certain investors, pre-funded warrants to purchase 8,445,333 shares of common stock. The pre-funded warrants were sold at a public offering price of $ 2.3999 per pre-funded warrant, which represents the per share public offering price of each share of common stock minus the $ 0.0001 per share exercise price for each pre-funded warrant. The pre-funded warrants do not have an expiration date and are exercisable at any time. The pre-funded warrants are classified as equity within the Company's unaudited consolidated balance sheet. The Company received net proceeds from the Offering, after deducting the underwriting discount and commissions and other estimated offering expenses, of approximately $ 91.7 million. The Company may receive nominal proceeds, if any, from the exercise of the pre-funded warrants. The following provides a roll forward of outstanding pre-funded warrants to purchase common stock as of September 30, 2024: Issuance Date Number of Shares of Common Stock Issuable Weighted Average Exercise Price Outstanding, December 31, 2023 — — Warrants issued 8,445,333 0.0001 Warrants exercised — — Warrants forfeited — — Outstanding, September 30, 2024 8,445,333 0.0001

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	11. Stock-based Compensation Stock-based Compensation Expense Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Research and development $ 3,622 $ 2,545 $ 8,833 $ 7,132 General and administrative 3,155 3,015 9,627 8,216 Total stock-based compensation $ 6,777 $ 5,560 $ 18,460 $ 15,348 Stock Options A summary of stock option activity for the nine months ended September 30, 2024 is set forth below: Number of Weighted Weighted- Aggregate Outstanding, December 31, 2023 9,383,105 $ 10.64 8.2 $ 45 Options granted 7,474,253 $ 2.48 Options exercised ( 92,283 ) $ 2.12 Options forfeited or cancelled ( 1,066,445 ) $ 10.66 Outstanding, September 30, 2024 15,698,630 $ 3.12 8.4 $ 15 Options exercisable, September 30, 2024 6,699,537 $ 3.58 7.6 $ 1 Vested and expected to vest, September 30, 2024 15,698,630 $ 3.12 8.4 $ 15 The assumptions used in the Black-Scholes option-pricing model to calculate stock-based compensation are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Fair value of common stock $ 1.44 - $ 1.55 $ 1.37 - $ 3.38 $ 1.21 - $ 3.12 $ 1.37 - $ 9.15 Expected term (years) 5.77 - 6.08 5.5 - 6.1 5.5 - 6.08 5.5 - 6.1 Volatility 85.32 % - 86.64 % 84.7 % - 87.3 % 82.15 % - 86.64 % 83.3 % - 87.3 % Risk free rates 3.63 % - 3.99 % 4.1 % - 4.6 % 3.63 % - 4.52 % 3.5 % - 4.6 % Dividend rate 0.0 % 0.0 % 0.0 % 0.0 % Restricted Stock Units (RSUs) The summary of RSU activity and related information for the nine months ended September 30, 2024 is set forth below: Number of Units Outstanding Weighted Average Outstanding, December 31, 2023 454,200 $ 7.69 RSUs granted 537,400 $ 2.60 RSUs vested ( 184,380 ) $ 7.15 RSUs forfeited ( 41,364 ) $ 4.21 Outstanding, September 30, 2024 765,856 $ 4.40 Option repricing On August 8, 2023, the board of directors approved a stock option repricing (the Option Repricing) effective on August 14, 2023 (the Effective Date) in accordance with the terms of the Company’s 2015 Stock Incentive Plan (the 2015 Plan) and Second Amended and Restated 2018 Stock Option and Incentive Plan (the 2018 Plan, and together with the 2015 Plan, the Plans). Pursuant to the Option Repricing, the exercise price of each stock option previously granted under the Plans, totaling 6,431,077 options, was amended to reduce the exercise price of such options to $ 2.14 per share, the closing price of the Company’s common stock on the Nasdaq Global Market on the Effective Date. The repriced options otherwise retained their existing terms and conditions as set forth in the Plans and applicable award agreements. The stock option modification resulted in $ 4.6 million of incremental compensation cost, which was calculated using the Black-Scholes option-pricing model. Of the incremental compensation cost, $ 0.6 million and $ 2.2 million was recognized in the three and nine months ended September 30, 2024 , respectively, compared to $ 0.4 million recognized in the three and nine months ended September 30, 2023. Additionally, $ 0.8 million will be recognized on the straight-line basis over the remaining vesting period of the repriced options. The incremental cost is included in general and administrative expense and research and development expense on the condensed consolidated statements of operations. Effective August 21, 2024, the board of directors approved a rescission of the Option Repricing for certain non-employee directors of the Company. All of the affected stock options have been reverted to their original exercise price as established at the time of the grant. The Company will continue to recognize the incremental fair value from the Option Repricing for the impacted options. The compensation expense associated with the Option Repricing for these options was not material.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Net Loss per Share	12. Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Net loss - basic and diluted $ ( 30,478 ) $ ( 49,885 ) $ ( 88,395 ) $ ( 113,169 ) Weighted-average shares used in computing net loss per share, basic and diluted 90,846,293 42,980,641 86,865,285 43,001,901 Net loss per share, basic and diluted ( 0.34 ) ( 1.16 ) ( 1.02 ) ( 2.63 ) The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the period presented because including them would have been antidilutive: As of September 30, 2024 2023 Options to purchase common stock 15,698,630 9,749,498 Unvested restricted stock units 765,856 586,800 Total 16,464,486 10,336,298

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company recognized no income tax expense during the three and nine months ended September 30, 2024 and 2023. The Company maintains a full valuation allowance against its deferred tax assets due to the Company’s history of losses as of September 30, 2024 .

Related Party

Related Party	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party	14. Related Party As of September 30, 2024 , Regeneron owned 883,568 shares of the Company’s common stock. Regeneron became a related party in July 2019 as a result of Series B redeemable convertible preferred stock financing which was subsequently converted into common stock. For the three and nine months ended September 30, 2024 , the Company recorded no revenue from the Regeneron Agreement. See Note 8 for a discussion of the Regeneron Agreement.

Shanghai Adicet Biotechnology C

Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE)	15. Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE) In May 2024, the Company initiated research and development activities in China through a series of contractual agreements entered into by and among the Adicet VIE, Adicet Shanghai, and the shareholders of the Adicet VIE. Since the Company determined it was the primary beneficiary of the Adicet VIE, the Adicet VIE was consolidated in the Company’s condensed consolidated financial statements as of September 30, 2024. For the three months and nine months ended September 30, 2024, $ 0.6 million of expenses have been incurred by the Adicet VIE, of which $ 0.5 million was recorded as research and development expense and $ 0.1 million as general and administrative expense in the Company’s condensed consolidated statements of operations. The following table summarizes the carrying amount of assets and liabilities of the Adicet VIE as of September 30, 2024, excluding intercompany balances (in thousands): September 30, Prepaid expenses and other current assets 9 Property and equipment, net 4 Accrued and other current liabilities 8

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 unaudited interim consolidated financial statements and related disclosures have been prepared in conformity with U.S. GAAP.
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, "Summary of Significant Accounting Policies," to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. There have been no material changes to the significant accounting policies during the nine months ended September 30, 2024 .
Principles of Consolidation	Principles of Consolidation The Company assesses entities for consolidation based on the specific facts and circumstances surrounding that entity. The Company first considers whether an entity is considered a variable interest entity (VIE) and therefore whether to apply the consolidation guidance under the VIE model. Entities that do not qualify as VIEs are assessed for consolidation as voting interest entities under the voting interest model. An entity is considered to be a VIE if any of the following conditions exist: (i) the equity investment at risk is not sufficient to finance the activities of the entity without additional subordinated financial support, (ii) as a group, the holders of the equity investment at risk lack the power to direct the activities that most significantly impact the entity’s economic performance or the obligation to absorb the expected losses or right to receive the expected residual returns, and (iii) the voting rights of some holders of the equity investment at risk are disproportionate to their obligation to absorb losses or right to receive returns, and substantially all of the activities are conducted on behalf of the holder of equity investment at risk with disproportionately few voting rights. The Company consolidates all VIEs in which it is the primary beneficiary. An entity is determined to be the primary beneficiary if it holds a controlling financial interest in a VIE. The consolidation guidance requires an analysis to determine (i) whether an entity in which the Company holds a variable interest is a VIE and (ii) whether the Company’s involvement, through holding interest directly or indirectly in the entity or contractually through other variable interests, would give it a controlling financial interest. Performance of that analysis requires judgment. As described in Note 1, Shanghai Adicet Biotechnology Co., Ltd., has been identified as a VIE and the Company is the primary beneficiary. Refer to Note 15 for additional information and operating activities for the VIE as of September 30, 2024 .
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited consolidated financial statements as of September 30, 2024, and for the three and nine months ended September 30, 2024, have been prepared by the Company, pursuant to the rules and regulations of the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2023. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s consolidated financial position as of September 30, 2024 and consolidated results of operations for the three and nine months ended September 30, 2024 and 2023 and consolidated cash flows for the nine months ended September 30, 2024 and 2023 have been made. The results of operations for the three and nine months ended September 30, 2024 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2024.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash, cash equivalents and short-term investments in treasury securities. The Company’s cash and cash equivalents, as well as its short-term investments in treasury securities, are held at two financial institutions in the U.S., one financial institution in China and one financial institution in Israel and such amounts may, at times, exceed insured limits. The Company invests its cash equivalents in treasury securities and money market funds. The Company limits its credit risk associated with cash equivalents and short-term investments in treasury securities by placing them with banks and institutions it believes are highly creditworthy and in highly rated investments. The Company has not experienced any losses on its deposits of cash and cash equivalents or its short-term investments in treasury securities to date.
Risks and Uncertainties	Risks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical studies, clinical trials, and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance and reporting. The Company’s product candidates are still in development and, to date, none of the Company’s product candidates have been approved for sale and, therefore, the Company has not generated any revenue from product sales. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biotechnology companies.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Accounting Pronouncements Not Yet Adopted In September 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which enhances the transparency and usefulness of income tax disclosures. This amendment requires public issuers to disclose specific categories in the rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold (if the effect of those reconciling items is equal to or greater than 5 percent of the amount computed by multiplying pretax income, or loss, by the applicable statutory income tax rate. Additionally, this amendment requires issuers to disclose the amount of income taxes paid (net of refunds received) disaggregated by federal (national), state, and foreign taxes as well as the amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which income taxes paid (net of refunds received) is equal to or greater than 5 percent of total income taxes paid (net of refunds received). For SEC filers, this ASU is effective for fiscal years beginning after December 15, 2025. Early adoption is permitted. The Company is currently evaluating the impact the adoption that this ASU will have on its consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures , which enables investors to better understand an entity's overall performance and assists with assessing potential future cash flows. This amendment improves financial reporting by requiring disclosure of incremental segment information on an annual and interim basis for all public entities to enable investors to develop more decision-useful financial analyses. It is applicable to all public entities that are required to report segment information in accordance with Topic 280, Segment Reporting. For SEC filers, this ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact the adoption that this ASU will have on its consolidated financial statements and related disclosures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured on Recurring Basis	September 30, 2024 Level 1 Level 2 Level 3 Total Assets: Treasury securities (1) (3) $ 96,583 $ — $ — $ 96,583 Treasury securities (2) (3) $ 32,854 $ — $ — $ 32,854 Money market funds (2) (3) $ 28,849 $ — $ — $ 28,849 Total fair value of assets $ 158,286 $ — $ — $ 158,286 December 31, 2023 Level 1 Level 2 Level 3 Total Assets: Treasury securities (2) (3) $ 115,143 $ — $ — $ 115,143 Total fair value of assets $ 115,143 $ — $ — $ 115,143 (1) Included in short-term investments in treasury securities in the consolidated balance sheets. These securities have maturity dates of greater than three months, but less than twelve months from the date of purchase. (2) Included in cash and cash equivalents in the consolidated balance sheets. These securities have maturity dates of less than three months from the date of purchase. (3) Treasury securities and money market funds are included within Level 1 of the fair value hierarchy because they are actively traded and valued using quoted market prices.

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, Prepayments to CROs and CDMOs $ 1,477 $ 53 Prepaid software subscription and licensing fees 664 582 Prepaid maintenance 544 373 Prepaid insurance 425 1,014 Prepaid employee benefits 306 — Interest receivable 210 — Prepaid professional services 82 82 Other prepaid expenses and current assets 543 457 Total prepaid expenses and other current assets $ 4,251 $ 2,561

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2024
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): Useful life September 30, December 31, Leasehold improvements Lesser of useful life or lease term $ 26,663 $ 26,643 Laboratory equipment 3 13,695 13,165 Furniture and fixtures 3 951 951 Construction in progress — 1,868 265 Computer equipment 3 193 189 Software 3 411 411 43,781 41,624 Less: Accumulated depreciation and amortization ( 19,693 ) ( 14,847 ) Property and equipment, net $ 24,088 $ 26,777

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2024
Payables and Accruals [Abstract]
Summary of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): September 30, December 31, Accrued compensation $ 6,103 $ 6,514 Accrued CDMO costs 4,810 5,679 Accrued professional services 506 625 Accrued other research and development expenses 1,685 354 Accrued CRO costs 489 257 Accrued other liabilities 23 12 Total accrued and other liabilities $ 13,616 $ 13,441

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Sublease Income	September 30, 2024 $ 180 2025 736 2026 438 2027 and thereafter — Total $ 1,354
Summary of Lease Costs and Other Information	The following table presents the operating lease cost and information related to the operating lease right-of-use assets, net and operating lease liabilities for the quarter ended September 30, 2024 (in thousands): Three Months Ended September 30, 2024 Lease Cost Operating lease cost $ 1,140 Short-term lease cost 32 Sublease income ( 182 ) Total lease cost $ 991 Other Information Operating cash flows used for lease liabilities $ ( 2,726 ) Weighted-average remaining lease term - operating leases 5.1 Weighted-average discount rate - operating leases 7 % For the nine months ended September 30, 2024 , the Company recognized $ 3.4 million and less than $ 0.1 million in operating lease and short-term lease costs, respectively. Additionally, for the nine months ended September 30, 2024 , the Company recognized $ 0.6 million in sublease income.
Schedule Of Future Lease payments	The future minimum lease payments under all non-cancelable operating lease obligations as of September 30, 2024 were as follows (in thousands): September 30, 2024 $ 1,274 2025 4,662 2026 4,009 2027 3,714 2028 and thereafter 8,376 Total undiscounted lease payments 22,035 Less: imputed interest ( 3,836 ) Total operating lease liability 18,199 Less: current portion ( 3,278 ) Operating lease liability, net of current maturities $ 14,921

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Schedule of Number of Shares of Common Stock Reserved for Future Issuance	The Company has the following shares of common stock reserved for future issuance: September 30, December 31, Stock options and restricted stock units available for future grant 2,302,470 2,473,485 Stock options issued and outstanding 15,698,630 9,383,105 Unvested restricted stock units 765,856 454,200 Common stock warrants issued and outstanding 8,445,333 — Total common stock reserved 27,212,289 12,310,790
Schedule Of Outstanding Warrants To Purchase Shares of Common Stock	The following provides a roll forward of outstanding pre-funded warrants to purchase common stock as of September 30, 2024: Issuance Date Number of Shares of Common Stock Issuable Weighted Average Exercise Price Outstanding, December 31, 2023 — — Warrants issued 8,445,333 0.0001 Warrants exercised — — Warrants forfeited — — Outstanding, September 30, 2024 8,445,333 0.0001

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Stock-Based Compensation Expense	Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Research and development $ 3,622 $ 2,545 $ 8,833 $ 7,132 General and administrative 3,155 3,015 9,627 8,216 Total stock-based compensation $ 6,777 $ 5,560 $ 18,460 $ 15,348
Summary of Stock Option Activity	Stock Options A summary of stock option activity for the nine months ended September 30, 2024 is set forth below: Number of Weighted Weighted- Aggregate Outstanding, December 31, 2023 9,383,105 $ 10.64 8.2 $ 45 Options granted 7,474,253 $ 2.48 Options exercised ( 92,283 ) $ 2.12 Options forfeited or cancelled ( 1,066,445 ) $ 10.66 Outstanding, September 30, 2024 15,698,630 $ 3.12 8.4 $ 15 Options exercisable, September 30, 2024 6,699,537 $ 3.58 7.6 $ 1 Vested and expected to vest, September 30, 2024 15,698,630 $ 3.12 8.4 $ 15
Schedule of Assumptions to Estimate Fair Value of Stock Options Using Black-Scholes Option Pricing Model	The assumptions used in the Black-Scholes option-pricing model to calculate stock-based compensation are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Fair value of common stock $ 1.44 - $ 1.55 $ 1.37 - $ 3.38 $ 1.21 - $ 3.12 $ 1.37 - $ 9.15 Expected term (years) 5.77 - 6.08 5.5 - 6.1 5.5 - 6.08 5.5 - 6.1 Volatility 85.32 % - 86.64 % 84.7 % - 87.3 % 82.15 % - 86.64 % 83.3 % - 87.3 % Risk free rates 3.63 % - 3.99 % 4.1 % - 4.6 % 3.63 % - 4.52 % 3.5 % - 4.6 % Dividend rate 0.0 % 0.0 % 0.0 % 0.0 %
Summary of Restricted Stock Unit Activity	The summary of RSU activity and related information for the nine months ended September 30, 2024 is set forth below: Number of Units Outstanding Weighted Average Outstanding, December 31, 2023 454,200 $ 7.69 RSUs granted 537,400 $ 2.60 RSUs vested ( 184,380 ) $ 7.15 RSUs forfeited ( 41,364 ) $ 4.21 Outstanding, September 30, 2024 765,856 $ 4.40

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Net loss - basic and diluted $ ( 30,478 ) $ ( 49,885 ) $ ( 88,395 ) $ ( 113,169 ) Weighted-average shares used in computing net loss per share, basic and diluted 90,846,293 42,980,641 86,865,285 43,001,901 Net loss per share, basic and diluted ( 0.34 ) ( 1.16 ) ( 1.02 ) ( 2.63 )
Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the period presented because including them would have been antidilutive: As of September 30, 2024 2023 Options to purchase common stock 15,698,630 9,749,498 Unvested restricted stock units 765,856 586,800 Total 16,464,486 10,336,298

Shanghai Adicet Biotechnology_2

Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE) (Tables)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summarizes the carrying amount of assets and liabilities of VIE	The following table summarizes the carrying amount of assets and liabilities of the Adicet VIE as of September 30, 2024, excluding intercompany balances (in thousands): September 30, Prepaid expenses and other current assets 9 Property and equipment, net 4 Accrued and other current liabilities 8

Organization and Nature of the

Organization and Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands					1 Months Ended		9 Months Ended
	Jan. 23, 2024	Jan. 22, 2024	Aug. 31, 2022	Mar. 12, 2021	Jan. 31, 2024	Nov. 30, 2022	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Schedule Of Equity Method Investments [Line Items]
Outstanding warrants, Weighted average exercise price		$ 2.3999
Aggregate net proceed					$ 19,300
Common stock price per share		$ 0.0001					$ 0.0001		$ 0.0001
Issuance of common stock		5,325,000					82,400,960		43,270,386
Estimated offering expenses	$ 91,700
Aggregate gross proceeds							$ 19,266	$ 0
Accumulated deficit							(469,167)		$ (380,772)
Underwriting discounts and commissions and other offering expenses		$ 91,700
Adicet Therapeutics [Member]
Schedule Of Equity Method Investments [Line Items]
Accumulated deficit							$ 469,200
Jefferies LLC
Schedule Of Equity Method Investments [Line Items]
Purchase price per share		$ 2.256
2021 Sales Agreement
Schedule Of Equity Method Investments [Line Items]
Aggregate number of shares sold			2,611,723
Sale of Stock, Price Per Share			$ 17.23
Sales agent commissions and expenses			$ 43,400
Common Stock not sold						$ 30,000
Additional Common Stock not sold						70,000
Aggregate gross proceeds						$ 100,000
Common Stock
Schedule Of Equity Method Investments [Line Items]
Issuance of common stock		5,325,000
Common Stock | Jefferies LLC
Schedule Of Equity Method Investments [Line Items]
Outstanding warrants, Weighted average exercise price		$ 2.4
Warrants outstanding		8,445,333
Common stock price per share		$ 0.0001
Issuance of common stock		27,054,667
Pre Funded Warrant | Jefferies LLC
Schedule Of Equity Method Investments [Line Items]
Underwriting agreement to purchase					30
Discount on underwriters warrant		6%
Purchase price per share		$ 2.2559
Outstanding warrants, Weighted average exercise price		2.3999
Pre Funded Warrant | Jefferies LLC | Initial Public Offering
Schedule Of Equity Method Investments [Line Items]
Outstanding warrants, Weighted average exercise price		$ 0.0001
Maximum | 2021 Sales Agreement
Schedule Of Equity Method Investments [Line Items]
Aggregate gross proceeds				$ 75,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands		Sep. 30, 2024		Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		$ 158,286		$ 115,143
Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		158,286		115,143
Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		0		0
Fair Value, Inputs, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		0		0
Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2]	96,583	[1]	115,143	[3]
Treasury Securities | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2]	96,583	[1]	115,143	[3]
Treasury Securities | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2]	0	[1]	0	[3]
Treasury Securities | Fair Value, Inputs, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2]	0	[1]	$ 0	[3]
Treasury securities (2) (3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	32,854
Treasury securities (2) (3) | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	32,854
Treasury securities (2) (3) | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	0
Treasury securities (2) (3) | Fair Value, Inputs, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	0
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	28,849
Money Market Funds | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	28,849
Money Market Funds | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	0
Money Market Funds | Fair Value, Inputs, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	[2],[3]	$ 0
[1] Included in short-term investments in treasury securities in the consolidated balance sheets. These securities have maturity dates of greater than three months, but less than twelve months from the date of purchase. Treasury securities and money market funds are included within Level 1 of the fair value hierarchy because they are actively traded and valued using quoted market prices. Included in cash and cash equivalents in the consolidated balance sheets. These securities have maturity dates of less than three months from the date of purchase.

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepayments to CROs and CDMOs	$ 1,477	$ 53
Prepaid insurance	425	1,014
Prepaid software subscription and licensing fees	664	582
Prepaid maintenance	544	373
Prepaid employee benefits	306	0
Interest Receivable	210	0
Prepaid Professional Services	82	82
Other prepaid expenses and current assets	543	457
Total prepaid expenses and other current assets	$ 4,251	$ 2,561

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Lesser of useful life or lease term	Leasehold Improvements
Total property and equipment	$ 43,781	$ 41,624
Less: Accumulated depreciation and amortization	(19,693)	(14,847)
Property and equipment, net	24,088	26,777
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 13,695	13,165
Useful life (in years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 26,663	26,643
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 951	951
Useful life (in years)	3 years
Construction In Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,868	265
Useful life (in years)
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 193	189
Useful life (in years)	3 years
Software
Property Plant And Equipment [Line Items]
Total property and equipment	$ 411	$ 411
Useful life (in years)	3 years

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense			$ 4,845	$ 4,409
PropertyPlantAndEquipmentMember
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 1,600	$ 1,600	$ 4,800	$ 4,400

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Summary of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued compensation	$ 6,103	$ 6,514
Accrued CDMO costs	4,810	5,679
Accrued professional services	506	625
Accrued other research and development expenses	1,685	354
Accrued CRO costs	489	257
Accrued other liabilities	23	12
Total accrued and other liabilities	$ 13,616	$ 13,441

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Sep. 30, 2024	Apr. 30, 2024	Jan. 22, 2024	May 30, 2023	Mar. 13, 2023	Apr. 28, 2020
Class Of Warrant Or Right [Line Items]
Available under the Loan Agreement	$ 3.2
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 2.3999
Pacific western bank [Member]
Class Of Warrant Or Right [Line Items]
Total loan accounts outside				$ 2.5
Banc of California [Member]
Class Of Warrant Or Right [Line Items]
term loan to finance leasehold improvements 1						$ 5.5
Demand Deposit Accounts				35
Combined balances in demand deposit accounts					$ 200
Term Loan cash maintain				$ 35
Banc of California [Member] | Maximum
Class Of Warrant Or Right [Line Items]
term loan to finance leasehold improvements 1		$ 5.5				15
Banc of California [Member] | Minimum
Class Of Warrant Or Right [Line Items]
term loan to finance leasehold improvements 1						$ 1

Third Party Agreements - Additi

Third Party Agreements - Additional Information (Details) - USD ($) $ in Millions		9 Months Ended
	Jan. 28, 2022	Sep. 30, 2024
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development in process 1		$ 1
License agreement termination description		twelve (12) years
Regeneron Pharmaceuticals, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized		$ 5
Exercise Fee Paid	$ 20	20
Licence agreement additional revenue recognised		25
Non refundable upfront payment received		25
Additional payment for research funding received		20
Regeneron Pharmaceuticals, Inc. | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Licence agreement additional amount payable of option exercise fees		$ 80

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands		3 Months Ended	9 Months Ended
	Jan. 09, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 01, 2023 USD ($)	Jul. 19, 2021 ft²
Long Term Purchase Commitment [Line Items]
Area of sublease | ft²					9,501
Short-term lease cost		$ 32	$ 100
Sublease income		182	600
Operating lease cost		$ 1,140	3,400
Operating lease payments			$ 1,200
Westport Office Park, LLC [Member]
Long Term Purchase Commitment [Line Items]
Tenant improvements	$ 3,000
Debt instrument, basis spread on variable rate	8%
Letters of credit				$ 2,100

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Sublease Income (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 180
2025	736
2026	438
2027 and thereafter	0
Total	$ 1,354

Commitments and Contingencies_3

Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024	$ 1,274
2025	4,662
2026	4,009
2027	3,714
2028 and thereafter	8,376
Total undiscounted lease payments	22,035
Less: imputed interest	(3,836)
Total operating lease liability	18,199
Less: current portion	(3,278)	$ (3,221)
Operating lease liability, net of current portion	$ 14,921	$ 17,703

Commitments and Contingencies_4

Commitments and Contingencies - Summary of Lease Costs and Other Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,140	$ 3,400
Short-term lease cost	32	100
Sublease Income	(182)	$ (600)
Total lease cost	991
Operating cash flows used for lease liabilities	$ (2,726)
Weighted-average remaining lease term - operating leases	5 years 1 month 6 days	5 years 1 month 6 days
Weighted-average discount rate - operating leases	7%	7%

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 22, 2024	Sep. 30, 2024	Dec. 31, 2023
Class Of Stock [Line Items]
Common Stock, Shares Subscribed but Unissued	32,379,667
Common stock, shares issued	5,325,000	82,400,960	43,270,386
Common stock, shares authorized		300,000,000	150,000,000
Underwriting discounts and commissions and other offering expenses	$ 91,700
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.3999
Exercise of warrant, shares	8,445,333
Dividends Payable		$ 0
Common stock shares issued, par value	$ 0.0001	$ 0.0001	$ 0.0001

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	27,212,289	12,310,790
Unvested Restricted Stock Units
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	765,856	454,200
Stock Options Available for Future Grant
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	2,302,470	2,473,485
Employee Stock Option
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	15,698,630	9,383,105
Common Stock Warrants
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	8,445,333	0

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Outstanding Warrants to Purchase Shares of Common Stock (Details)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Weighted-Average Exercise Price, Outstanding beginning	$ 10.64
Weighted-Average Exercise Price, Options granted	2.48
Weighted-Average Exercise Price, Options exercised	2.12
Weighted-Average Exercise Price, Outstanding ending	$ 3.12
Warrant
Outstanding, December 31, 2023 | shares	0
Number of shares of common stock issuable, Issued | shares	8,445,333
Number of shares of common stock issuable, Exercised | shares	0
Number of shares of common stock issuable, Forfeited | shares	0
Outstanding, September 30, 2024 | shares	8,445,333
Weighted-Average Exercise Price, Outstanding beginning	$ 0
Weighted-Average Exercise Price, Options granted	0.0001
Weighted-Average Exercise Price, Options exercised	0
Weighted Average Exercise Price, Warrants forfeited	0
Weighted-Average Exercise Price, Outstanding ending	$ 0.0001

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (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 expense	$ 6,777	$ 5,560	$ 18,460	$ 15,348
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	3,622	2,545	8,833	7,132
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 3,155	$ 3,015	$ 9,627	$ 8,216

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Number of Shares Underlying Outstanding Options, Beginning balance	9,383,105
Number of Shares Underlying Outstanding Options, Options granted	7,474,253
Number of Shares Underlying Outstanding Options, Options exercised	(92,283)
Number of Shares Underlying Outstanding Options, Options forfeited or cancelled	(1,066,445)
Number of Shares Underlying Outstanding Options, Ending balance	15,698,630	9,383,105
Number of Shares Underlying Outstanding Options exercisable	6,699,537
Number of Shares Underlying Outstanding Options, Vested and expected to vest	15,698,630
Weighted-Average Exercise Price, Outstanding beginning	$ 10.64
Weighted-Average Exercise Price, Options granted	2.48
Weighted-Average Exercise Price, Options exercised	2.12
Weighted-Average Exercise Price, Options forfeited or cancelled	10.66
Weighted-Average Exercise Price, Outstanding ending	3.12	$ 10.64
Weighted-Average Exercise Price, Options exercisable	3.58
Weighted-Average Exercise Price, Vested and expected to vest	$ 3.12
Weighted-Average Remaining Contract Term, Outstanding	8 years 4 months 24 days	8 years 2 months 12 days
Weighted-Average Remaining Contract Term, Options exercisable	7 years 7 months 6 days
Weighted-Average Remaining Contract Term, Vested and expected to vest	8 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 15	$ 45
Aggregate Intrinsic Value, Options exercisable	1
Aggregate Intrinsic Value, Vested and expected to vest	$ 15

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Aug. 08, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-Based Payment Arrangement, Plan Modification, Incremental Cost		$ 0.6	$ 0.4	$ 2.2	$ 0.4
Black-Scholes option-pricing model [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-Based Payment Arrangement, Incremental Cost, Amount recognized over the remaining vesting period of the repriced options				$ 0.8
Share-Based Payment Arrangement, Plan Modification, Incremental Cost	$ 4.6
2015 Stock Incentive Plan Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Available for Grant, Options granted	6,431,077
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Exercise Price	$ 2.14

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Assumptions to Estimate Fair Value of Stock Options Using Black-Scholes Option Pricing Model (Details) - $ / shares	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]
Expected volatility, minimum	85.32%	84.70%	82.15%	83.30%
Expected volatility, maximum	86.64%	87.30%	86.64%	87.30%
Risk free rates, minimum	3.63%	4.10%	3.63%	3.50%
Risk free rates, maximum	3.99%	4.60%	4.52%	4.60%
Dividend rate	0%	0%	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 1.44	$ 1.37	$ 1.21	$ 1.37
Expected term	5 years 9 months 7 days	5 years 6 months	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 1.55	$ 3.38	$ 3.12	$ 9.15
Expected term	6 years 29 days	6 years 1 month 6 days	6 years 29 days	6 years 1 month 6 days

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Restricted Stock Unit Activity (Details)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, December 31, 2023 | shares	454,200
RSUs granted | shares	537,400
RSUs Vested | shares	(184,380)
RSUs forfeited | shares	(41,364)
Outstanding, June 30, 2024 | shares	765,856
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-Average Grant Date Fair Value, Beginning | $ / shares	$ 7.69
Weighted-Average Grant Date Fair Value, Granted | $ / shares	2.6
Weighted-Average Grant Date Fair Value,Vested | $ / shares	7.15
Weighted-Average Grant Date Fair Value, Forfeited | $ / shares	4.21
Weighted-Average Grant Date Fair Value, Ending | $ / shares	$ 4.4

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net loss - basic and diluted	$ (30,478)	$ (49,885)	$ (88,395)	$ (113,169)
Weighted-average shares used in computing net loss per share, diluted	90,846,293	42,980,641	86,865,285	43,001,901
Weighted-average shares used in computing net loss per share, basic	90,846,293	42,980,641	86,865,285	43,001,901
Net loss per share attributable to common stockholders, basic	$ (0.34)	$ (1.16)	$ (1.02)	$ (2.63)
Net loss per share attributable to common stockholders, diluted	$ (0.34)	$ (1.16)	$ (1.02)	$ (2.63)

Net Loss per Share - Schedule_2

Net Loss per Share - Schedule of Potentially Dilutive 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]
Antidilutive securities excluded from computation of earnings per share	16,464,486	10,336,298
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	15,698,630	9,749,498
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	765,856	586,800

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Taxes Disclosure [Line Items]
Income tax provision	$ 0	$ 0	$ 0	$ 0
COVID-19
Income Taxes Disclosure [Line Items]
Income tax provision	$ 0	$ 0	$ 0	$ 0

Related Party - Additional Info

Related Party - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Jan. 22, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Issuance of common stock	82,400,960	82,400,960	5,325,000	43,270,386
Regeneron Pharmaceuticals, Inc.
Related Party Transaction [Line Items]
Issuance of common stock	883,568	883,568
Revenue from related party	$ 0	$ 0

Shanghai Adicet Biotechnology_3

Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE) (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Variable Interest Entity [Line Items]
Expenses	$ 33,153	$ 52,262	$ 96,872	$ 120,472
Research and development Expense	26,253	26,167	76,050	81,284
General and administrative Expense	6,900	$ 6,633	20,822	$ 19,726
Adicet VIE [Member]
Variable Interest Entity [Line Items]
Expenses	600		600
Research and development Expense	500		500
General and administrative Expense	$ 100		$ 100

Shanghai Adicet Biotechnology_4

Shanghai Adicet Biotechnology Co., Ltd. (the Adicet VIE) - carrying amount of assets and liabilities of the Adicet VIE excluding intercompany balances (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Prepaid expenses and other current assets	$ 4,251	$ 2,561
Property and equipment, net	24,088	$ 26,777
Adicet VIE [Member]
Variable Interest Entity [Line Items]
Prepaid expenses and other current assets	9
Property and equipment, net	4
Accrued and other current liabilities	$ 8

Subsequent Events (Additional I

Subsequent Events (Additional Information) (Details)	Sep. 30, 2024 shares
Subsequent Event [Line Items]
Number of Shares Underlying Outstanding Options, Vested and Unvested	15,698,630