Adicet Bio (ACET) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 03, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2020
Entity Registrant Name	Adicet Bio, Inc.
Entity Central Index Key	0001720580
Trading Symbol	ACET
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	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	500 Boylston Street
Entity Address, Address Line Two	13th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	857
Local Phone Number	315-5528
Entity Common Stock, Shares Outstanding		19,600,567
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
Entity Incorporation, State or Country Code	DE

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 84,960	$ 10,607
Short-term marketable debt securities	23,160	51,793
Prepaid expenses and other current assets	9,291	1,786
Total current assets	117,411	64,186
Property and equipment, net	2,043	2,121
Goodwill	20,739
In-process research and development	3,490
Restricted cash	4,527	4,282
Long-term marketable debt securities		10,588
Other non-current assets	2,187	410
Total assets	150,397	81,587
Current liabilities:
Accounts payable	3,838	1,052
Contract liabilities — related party, current	19,390	10,993
Accrued and other current liabilities	6,849	2,820
Total current liabilities	30,077	14,865
Contract liabilities — related party, net of current portion		10,890
Deferred rent, net of current portion	102	234
Redeemable convertible preferred stock warrant liability		1,881
Contingent consideration liability	2,880
Deferred tax liability	367
Other liabilities	41
Total liabilities	33,467	27,870
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, value
Common stock, $0.0001 par value, 150,000,000 and 140,200,938 shares authorized as of September 30, 2020 and December 31, 2019, respectively; 19,589,637 and 2,155,578 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	1
Additional paid-in capital	214,213	9,258
Accumulated deficit	(97,367)	(69,647)
Accumulated other comprehensive income	83	23
Total stockholders’ equity (deficit)	116,930	(60,366)
Total liabilities, redeemable convertible preferred stock, and stockholders’ equity (deficit)	$ 150,397	81,587
Redeemable Convertible Preferred Stock
Stockholders’ equity:
Preferred stock, value		$ 114,083

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (unaudited) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	140,200,938
Common stock, shares issued	19,589,637	2,155,578
Common stock, shares outstanding	19,589,637	2,155,578
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
Redeemable Convertible Preferred Stock
Preferred Stock, par value	$ 0.0001	$ 0.0001
Preferred stock shares authorized	0	99,363,444
Preferred stock shares issued	0	97,166,921
Preferred stock shares outstanding	0	97,166,921
Preferred stock, liquidation preference, value	$ 0	$ 128,195

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue—related party	$ 3,028	$ (7,047)	$ 12,493	$ (974)
Operating expenses:
Research and development	8,942	6,331	24,651	17,168
General and administrative	7,741	1,847	17,684	6,069
Total operating expenses	16,683	8,178	42,335	23,237
Loss from operations	(13,655)	(15,225)	(29,842)	(24,211)
Interest income	153	276	704	561
Interest expense	(50)		(84)
Other income (expense), net	(1,224)	171	(1,174)	2,091
Loss before income tax expense (benefit)	(14,776)	(14,778)	(30,396)	(21,559)
Income tax expense (benefit)	3		(2,676)	1
Net loss	$ (14,779)	$ (14,778)	$ (27,720)	$ (21,560)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.84)	$ (6.87)	$ (8.69)	$ (10.10)
Weighted-average common shares used in computing net loss per share attributable to common stockholders, basic and diluted	5,208,887	2,149,986	3,190,557	2,133,645
Other comprehensive income:
Unrealized (loss) gain on marketable debt securities, net of tax	$ (114)	$ (5)	$ 60	$ 11
Total other comprehensive (loss) income	(114)	(5)	60	11
Comprehensive loss	$ (14,893)	$ (14,783)	$ (27,660)	$ (21,549)

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Pain In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2018	$ (33,516)		$ 1	$ 8,005	$ (41,509)	$ (13)
Balance, temporary equity, shares at Dec. 31, 2018		40,094,850
Balance, temporary equity at Dec. 31, 2018		$ 38,068
Balance, shares at Dec. 31, 2018			2,140,787
Issuance of redeemable convertible preferred stock		$ 88
Issuance of redeemable convertible preferred stock, shares		67,656
Issuance of common stock upon exercise of stock options	9			9
Issuance of common stock upon exercise of stock options, shares			4,300
Vesting of early exercised stock options	47			47
Stock-based compensation expense	251			251
Other comprehensive income	18					18
Net loss	(4,131)				(4,131)
Balance at Mar. 31, 2019	(37,322)		$ 1	8,312	(45,640)	5
Balance, temporary equity, shares at Mar. 31, 2019		40,162,506
Balance, temporary equity at Mar. 31, 2019		$ 38,156
Balance, shares at Mar. 31, 2019			2,145,087
Balance at Dec. 31, 2018	(33,516)		$ 1	8,005	(41,509)	(13)
Balance, temporary equity, shares at Dec. 31, 2018		40,094,850
Balance, temporary equity at Dec. 31, 2018		$ 38,068
Balance, shares at Dec. 31, 2018			2,140,787
Net loss	(21,560)
Unrealized (loss) gain on marketable debt securities, net of tax	11
Balance at Sep. 30, 2019	(54,129)		$ 1	8,941	(63,069)	(2)
Balance, temporary equity, shares at Sep. 30, 2019		97,166,921
Balance, temporary equity at Sep. 30, 2019		$ 114,212
Balance, shares at Sep. 30, 2019			2,152,268
Balance at Mar. 31, 2019	(37,322)		$ 1	8,312	(45,640)	5
Balance, temporary equity, shares at Mar. 31, 2019		40,162,506
Balance, temporary equity at Mar. 31, 2019		$ 38,156
Balance, shares at Mar. 31, 2019			2,145,087
Issuance of common stock upon exercise of stock options	7			7
Issuance of common stock upon exercise of stock options, shares			3,278
Stock-based compensation expense	223			223
Other comprehensive income	(2)					(2)
Net loss	(2,651)				(2,651)
Balance at Jun. 30, 2019	(39,745)		$ 1	8,542	(48,291)	3
Balance, temporary equity, shares at Jun. 30, 2019		40,162,506
Balance, temporary equity at Jun. 30, 2019		$ 38,156
Balance, shares at Jun. 30, 2019			2,148,365
Issuance of redeemable convertible preferred stock		$ 74,913
Issuance of redeemable convertible preferred stock, shares		57,004,415
Issuance of common stock upon exercise of stock options	8			8
Issuance of common stock upon exercise of stock options, shares			3,903
Termination of redeemable convertible preferred stock tranche liability		$ 1,143
Stock-based compensation expense	391			391
Other comprehensive income	(5)					(5)
Net loss	(14,778)				(14,778)
Unrealized (loss) gain on marketable debt securities, net of tax	(5)
Balance at Sep. 30, 2019	(54,129)		$ 1	8,941	(63,069)	(2)
Balance, temporary equity, shares at Sep. 30, 2019		97,166,921
Balance, temporary equity at Sep. 30, 2019		$ 114,212
Balance, shares at Sep. 30, 2019			2,152,268
Balance at Dec. 31, 2019	(60,366)			9,258	(69,647)	(23)
Balance, temporary equity, shares at Dec. 31, 2019		97,166,921
Balance, temporary equity at Dec. 31, 2019	114,083	$ 114,083
Balance, shares at Dec. 31, 2019			2,155,578
Issuance of common stock upon exercise of stock options	42			42
Issuance of common stock upon exercise of stock options, shares			19,947
Stock-based compensation expense	299			299
Net loss	(4,486)				(4,486)
Unrealized (loss) gain on marketable debt securities, net of tax	(15)					(15)
Balance at Mar. 31, 2020	(64,526)			9,599	(74,133)	8
Balance, temporary equity, shares at Mar. 31, 2020		97,166,921
Balance, temporary equity at Mar. 31, 2020		$ 114,083
Balance, shares at Mar. 31, 2020			2,175,525
Balance at Dec. 31, 2019	(60,366)			9,258	(69,647)	(23)
Balance, temporary equity, shares at Dec. 31, 2019		97,166,921
Balance, temporary equity at Dec. 31, 2019	114,083	$ 114,083
Balance, shares at Dec. 31, 2019			2,155,578
Conversion of redeemable convertible preferred stock warrants to common stock warrants	114,083
Net loss	(27,720)
Unrealized (loss) gain on marketable debt securities, net of tax	60
Balance at Sep. 30, 2020	116,930		$ 1	214,213	(97,367)	83
Balance, temporary equity, shares at Sep. 30, 2020		0
Balance, shares at Sep. 30, 2020			19,589,637
Balance at Mar. 31, 2020	(64,526)			9,599	(74,133)	8
Balance, temporary equity, shares at Mar. 31, 2020		97,166,921
Balance, temporary equity at Mar. 31, 2020		$ 114,083
Balance, shares at Mar. 31, 2020			2,175,525
Issuance of common stock upon exercise of stock options	7			7
Issuance of common stock upon exercise of stock options, shares			3,101
Stock-based compensation expense	351			351
Net loss	(8,455)				(8,455)
Unrealized (loss) gain on marketable debt securities, net of tax	189					189
Balance at Jun. 30, 2020	(72,434)			9,957	(82,588)	197
Balance, temporary equity, shares at Jun. 30, 2020		97,166,921
Balance, temporary equity at Jun. 30, 2020		$ 114,083
Balance, shares at Jun. 30, 2020			2,178,626
Issuance of common stock upon exercise of stock options	144			144
Issuance of common stock upon exercise of stock options, shares			100,092
Stock-based compensation expense	2,966			2,966
Conversion of shares of redeemable convertible preferred stock to shares of common stock in connection with the Merger	114,083		$ 1	114,082
Conversion of shares of redeemable convertible preferred stock to shares of common stock in connection with the Merger, shares		(97,166,921)
Conversion of shares of redeemable convertible preferred stock to shares of common stock in connection with the Merger		$ (114,083)
Conversion of shares of redeemable convertible preferred stock to shares of common stock in connection with the Merger, shares			12,048,671
Exchange of common stock in connection with the Merger	84,142			84,142
Exchange of common stock in connection with the Merger, shares			5,262,248
Conversion of redeemable convertible preferred stock warrants to common stock warrants	2,922			2,922
Net loss	(14,779)				(14,779)
Unrealized (loss) gain on marketable debt securities, net of tax	(114)					(114)
Balance at Sep. 30, 2020	$ 116,930		$ 1	$ 214,213	$ (97,367)	$ 83
Balance, temporary equity, shares at Sep. 30, 2020		0
Balance, shares at Sep. 30, 2020			19,589,637

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	3 Months Ended
	Sep. 30, 2019USD ($)
Series B Redeemable Convertible Preferred Stock
Stock issuance cost	$ 5,087

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (27,720)	$ (21,560)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	911	962
Stock-based compensation expense	3,616	865
Gain on disposal of property and equipment		3
Net amortization of premiums and accretion discounts on investments	(4)	(143)
Change in fair value of redeemable convertible preferred stock tranche liability and TRDF liability		(2,024)
Change in fair value of redeemable convertible preferred stock warrant liability	897	(62)
Amortization of deferred debt issuance costs	84
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(5,000)	837
Other non-current assets	(1,560)	19
Accounts payable	1,442	244
Contract liabilities — related party	(2,493)	974
Deferred rent	(119)	(111)
Accrued and other current liabilities	1,738	(627)
Other liabilities	1
Net cash used in operating activities	(28,207)	(20,623)
Cash flows from investing activities
Cash and restricted cash acquired in connection with the Merger	64,114
Purchases of marketable debt securities	(5,700)	(60,056)
Proceeds from maturities of marketable debt securities	44,985	17,750
Purchases of property and equipment	(630)	(611)
Net cash provided by (used in) investing activities	102,769	(42,917)
Cash flows from financing activities
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		77,044
Proceeds from exercise of stock options	193	24
Deferred debt issuance costs	(157)
Net cash provided by financing activities	36	77,068
Net change in cash, cash equivalents and restricted cash	74,598	13,528
Cash, cash equivalents and restricted cash, at the beginning of period	14,889	13,757
Cash, cash equivalents and restricted cash, at the end of period	89,487	27,285
Reconciliation of cash, cash equivalents and restricted cash to condensed consolidated balance sheets:
Cash, cash equivalents and restricted cash in condensed consolidated balance sheets	89,487	27,285
Supplemental cash flow information
Cash paid for income taxes	3	1
Supplemental disclosures of noncash investing and financing activities
Purchases of property and equipment included in accounts payable	76	58
Conversion of redeemable convertible preferred stock warrants to common stock warrants	114,083
Conversion of redeemable convertible preferred stock warrants into common stock warrants	2,922
Fair value of net assets acquired in Merger	84,142
Vesting of early exercised stock options		47
Issuance of redeemable convertible preferred stock warrants in connection with the Loan Agreement	$ 144
Termination of redeemable convertible preferred stock tranche liability		1,143
Settlement of TRDF liability		88
Series B Redeemable Convertible Preferred Stock
Supplemental disclosures of noncash investing and financing activities
Redeemable convertible preferred stock warrants issued in exchange for services in connection with issuance of Series B redeemable convertible preferred stock recorded as issuance costs		$ 2,131

Organization and Nature of Busi

Organization and Nature of Business	9 Months Ended
	Sep. 30, 2020
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 biotechnology company discovering and developing allogeneic gamma delta T cell therapies for cancer and other diseases. The Company is advancing a pipeline of “off-the-shelf” gamma delta T cells, engineered with chimeric antigen receptors and T cell receptor-like antibodies to enhance selective tumor targeting, facilitate innate and adaptive anti-tumor immune response, and improve persistence for durable activity in patients. The Company believes its approach has potentially significant advantages over alpha beta T cells, which are the basis of standard CAR-T cell therapies. The Company was incorporated in November 2014 Adicet Bio, Inc. (when referred to prior to the Merger (as defined below), (“Former Adicet”)) was incorporated in November 2014 in Delaware and was headquartered in Menlo Park, California. Merger with resTORbio Prior to September 15, 2020, the Company was a clinical-stage biopharmaceutical company known as resTORbio that had historically focused on developing innovative medicines that target the biology of aging, to prevent or treat age-related diseases with the potential to extend healthy lifespans. On April 28, 2020, resTORbio entered into a definitive merger agreement with Former Adicet to create a combined publicly-traded biotechnology company whose anticipated focus will be on the development of the Company’s off-the-shelf allogeneic gamma delta T cell therapies for oncology and other indications. Under the terms of the merger agreement, Former Adicet agreed to merge 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.” (such transactions, the “Merger”). Under the exchange ratio formula in the merger agreement, immediately following the effective time of the Merger, the securityholders of Former Adicet as of immediately prior to the effective time of the Merger owned approximately 75% of the outstanding shares of the Company’s common stock on a fully-diluted basis and securityholders of resTORbio as of immediately prior to the effective time of the Merger owned approximately 25% of the outstanding shares of the Company’s common stock on a fully-diluted basis (in each case excluding equity incentives available for grant). The Company has concluded that the transaction represents a business combination pursuant to Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 805, Business Combinations On September 15, 2020, the Company completed the Merger pursuant to the merger agreement (the “Effective Time”). In connection with the Merger, and immediately prior to the Effective Time, the Company effected a reverse stock split of the Company’s common stock at a ratio of 1-for-7 (the “Reverse Stock Split”). Also, in connection with the Merger, the Company changed its name from “resTORbio, Inc.” to “Adicet Bio, Inc.” (the “Name Change”), Former Adicet changed its name from “Adicet Bio, Inc.” to “Adicet Therapeutics, Inc.” and the business conducted by the Company became primarily the business which was previously conducted by Former Adicet, which is a biotechnology company discovering and developing allogeneic gamma delta T cell therapies for cancer and other diseases.. At the Effective Time, each outstanding share of Former Adicet capital stock was converted into the right to receive 0.1240 (the “Exchange Ratio”) shares of Company’s common stock, as set forth in the merger agreement. The Exchange Ratio was determined based on the total number of outstanding shares of Company’s common stock and Former Adicet capital stock, each on a fully diluted basis, and the respective valuations of Former Adicet and resTORbio at the time of execution of the Merger Agreement. In connection with the Merger, the Company also assumed certain outstanding Former Adicet warrants and Former Adicet stock options under Former Adicet’s 2015 Stock Incentive Plan (the “2015 Adicet Stock Incentive Plan”) and Former Adicet’s 2014 Share Option Plan (the “2014 Share Option Plan” and, together with the 2015 Adicet Stock Incentive Plan, the “Former Adicet Plans”), with such stock options and warrants henceforth representing the right to purchase a number of shares of Company ’s c ommon s tock equal to the Exchange Ratio multiplied by the number of shares of Former Adicet’s capital stock previously represented by such stock options and warrants, as applicable, with a proportionate adjustment in exercise price. In connection with the Merger, the Company also assumed the Former Adicet Plans . Immediately following the Effective Time, there were approximately 19,589,828 shares of the Company’s common stock outstanding (post Reverse Stock Split). Immediately following the Effective Time, the former equity holders of Adicet held approximately 75% of the outstanding shares of Company’s common stock on a fully-diluted basis and the former equity holders of resTORbio held approximately 25% of the outstanding shares of Company’s common stock on a fully-diluted basis (in each case excluding equity incentives available for grant) Please refer to Note 3 “Business Combinations” for further details of the Merger. Liquidity The Company had $108.1 million in cash, cash equivalents, and marketable debt securities and an accumulated deficit of $97.4 million as of September 30, 2020. The Company has historically financed its operations primarily through a collaboration and licensing arrangement, through the private placement of equity securities and debt, and cash received in the Merger. 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. The Company expects that its cash and cash equivalents 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 condensed consolidated financial statements. All of the Company’s revenue to date is generated from the Regeneron Agreement, which is a collaboration and license agreement. The Company does not expect to generate any significant product revenue until it obtains regulatory approval of and commercialize any of the Company’s product candidates or enter 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 seek regulatory approvals for, its product candidates and begin 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 manufacturing organizations (“CMOs”), 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, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The unaudited interim condensed consolidated financial statements and related disclosures have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Principles of Consolidation The interim condensed consolidated financial statements include the accounts of the Company and its Reverse Stock Split On September 15, 2020, immediately before the closing of the Merger, resTORbio effected a Unaudited Interim Financial Information The condensed consolidated balance sheet as of December 31, 2019 was derived from the Company’s audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited condensed consolidated financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019, have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”), for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with 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 condensed 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, 2019 included in the Company’s Current Report on Form 8-K filed with the Securities and Exchange Commission on September 16, 2020. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s condensed consolidated financial position as of September 30, 2020 and condensed consolidated results of operations for the three and nine months ended September 30, 2020 and 2019 and condensed consolidated cash flows for the nine months ended September 30, 2020 and 2019 have been made. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2020. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements as well as the reported amounts of revenues and expenses during the reporting period. Such estimates include the valuation of the intangible assets acquired in business combinations, redeemable convertible preferred stock warrant liability, redeemable convertible preferred stock tranche liability, the Technion Research and Development Foundation liability (“TRDF Liability”), contingent consideration liability for contingent value right (“CVR”), deferred tax assets, useful lives of property and equipment, accruals for research and development activities, revenue recognition and stock-based compensation. Actual results could differ from those estimates. The current COVID-19 (coronavirus) pandemic, which is impacting worldwide economic activity, poses risk that the Company or its employees, contractors, suppliers, and other partners may be prevented from conducting business activities for an indefinite period of time, including due to shutdowns that may be requested or mandated by governmental authorities. The extent to which the coronavirus impacts the Company’s operations will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration of the outbreak, new information that will emerge concerning the severity of the coronavirus and the actions to contain the coronavirus or treat its impact, among others. COVID-19 may impact the timing of regulatory approval of the INDs for clinical trials, the enrollment of any clinical trials that are approved, the availability of clinical trial materials and regulatory approval and commercialization of our products. COVID-19 may also impact the Company’s ability to access capital, which could negatively impact short-term and long-term liquidity. Business Combinations Business combinations are accounted for under the acquisition method. The Company recognizes the assets acquired and liabilities assumed in business combinations on the basis of their fair values at the date of acquisition. The Company assesses the fair value of assets acquired, including intangible assets, and liabilities assumed using a variety of methods. Each asset acquired and liability assumed is measured at fair value from the perspective of a market participant. The method used to estimate the fair values of intangible assets incorporates significant estimates and assumptions regarding the estimates a market participant would make in order to evaluate an asset, including a market participant’s use of the asset, future cash inflows and outflows, probabilities of success, asset lives, and the appropriate discount rates. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. Any excess purchase price over the fair value of the net tangible and intangible assets acquired is allocated to goodwill. Transaction costs and restructuring costs associated with a business combination are expensed as incurred. During the measurement period, which extends no later than one year from the acquisition date, the Company may record certain adjustments to the carrying value of the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, all adjustments are recorded in the condensed consolidated statements of operations as operating expenses or income. Contingent Consideration Liability The estimated fair value of contingent consideration liability, initially measured and recorded on the acquisition date, is considered to be a Level 3 instrument. The contingent consideration liability is recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in research and development expenses in the condensed consolidated statements of operations. Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and identified intangible assets acquired in a business combination. Goodwill is not amortized but is evaluated at least annually for impairment or when a change in facts and circumstances indicate that the fair value of the goodwill may be below its carrying value. Goodwill is tested for impairment at the reporting unit level annually in the fourth quarter, or more frequently when events or changes in circumstances indicate that the asset might be impaired. Examples of such events or circumstances include, but are not limited to, a significant adverse change in legal or business climate, an adverse regulatory action or unanticipated competition. The Company has determined that it operates in a single operating segment and has a single reporting unit. Prior to performing the impairment test, t he Company assesses qualitative factors to determine whether the existence of events or circumstances would indicate that it is more likely than not that the fair value of the reporting unit was less than its carrying amount. If after assessing the totality of events or circumstances, the Company were to determine that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, then the Company would perform a quantitative impairment test. The quantitative impairment test involves comparing the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less than the carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over the fair value of the reporting unit. The Company has determined there were no indicators of goodwill impairment as of September 30, 2020. Intangible Assets In connection with the Merger, the Company acquired certain IPR&D assets, which were classified as indefinite-lived intangible assets. Acquired IPR&D represents the fair value assigned to research and development assets that the Company acquires and have not been completed at the acquisition date. The fair value of IPR&D acquired in a business combination is recorded on the Company’s condensed consolidated balance sheets at the acquisition-date fair value and is determined by estimating the costs to develop the technology into commercially viable products, estimating the resulting revenue from the products, and discounting the projected net cash flows to present value. IPR&D is not amortized, but rather is reviewed for impairment on an annual basis or more frequently if indicators of impairment are present, until the project is completed, abandoned, or transferred to a third party. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB ASC or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Recently Adopted Accounting Pronouncements In August 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Recently Issued Accounting Pronouncements In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848)

Business Combination

Business Combination	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Business Combination	3. Business Combination On September 15, 2020 resTORbio’s stockholders will continue to own and hold their existing shares of the Company’s common stock (after giving effect to the 1-for-7 reverse stock split). Pursuant to the terms of the Merger, For accounting purposes, the Company assumed 81,370 in-the-money resTORbio stock options after giving effect to reverse stock split. In addition, 91,309 unvested resTORbio restricted stock units outstanding and unsettled, after giving effect to reverse stock split, as of immediately prior to the effective time of the Merger, were accelerated in full and the holders of such restricted stock units received 55,854 shares of the Company’s common stock (after reduction by the number of shares of resTORbio common stock necessary to satisfy applicable tax withholding obligations at the maximum statutory rate). In connection with the Merger, the Company entered into a Contingent Value Rights Agreement (the “CVR Agreement”) with Computershare Inc. and Computershare Trust Company, N.A. as joint rights agent. Per the terms of the Merger, each holder of resTORbio common stock as of immediately prior to the completion of the Merger is entitled to one contractual contingent value right, subject to and in accordance with the terms and conditions of the CVR Agreement, for each share of resTORbio common stock held by such holder as of immediately prior to the Effective Time. The CVR holders are entitled to receive net proceeds from the commercialization, if any, received from a third-party commercial partner of RTB101, resTORbio’s small molecule product candidate that is a potent inhibitor of target of rapamycin complex 1 (TORC1), for a COVID-19 related indication. The CVR is accounted for as contingent consideration, the fair value of which was determined using an income approach. This approach utilized a that would accrue to the Company and then deducting the administrative fee to be retained by the Company and other permitted deductions in order to arrive at the net cash expected to be paid out to the CVR holders. These cash flows were then discounted to present value using the same discount rate applied in the valuation of the IPR&D. The probability adjusted discounted cash flow (refer to Note 4 “Fair Value Measurements”). The total purchase price has been allocated to the tangible and intangible assets acquired and liabilities assumed of resTORbio based on their fair values as of the completion of the Merger, with the excess allocated to goodwill. The purchase price is calculated based on the fair value of resTORbio common stock that the resTORbio stockholders owned as of the closing date of the merger because, with no active trading market for shares of Adicet, the fair value of the resTORbio’s common stock represented a more reliable measure of the fair value of consideration transferred in the Merger. Fair value of common stock shares of the combined company owned by resTORbio stockholders (1) $ 83,516 Fair value of contingent consideration liability with respect to CVR (2) 2,880 Estimated fair value of modified stock options and restricted stock units attributable to pre-combination services (3) 626 Purchase price $ 87,022 (1) Represents the share consideration of the combined company that the resTORbio stockholders own as of the closing of the merger calculated as follows: Number of shares of the combined company owned by resTORbio stockholders (a) 5,207,695 Multiplied by the fair value per share of resTORbio common $ 16.59 Acquisition date fair value of resTORbio 86,396 Less: portion of the fair value to be distributed as CVR (c) (2,880 ) Fair value of shares of the combined company owned by resTORbio stockholders $ 83,516 a. Represents the number of shares of common stock of the combined company that the resTORbio stockholders owned as of the closing of the merger. This amount is calculated as 5,207,695 shares of resTORbio common stock outstanding as of September 15, 2020. b. The purchase price is based on the closing price of resTORbio common stock on September 14, 2020. c. The fair value of resTORbio common stock was further adjusted to remove the estimated fair value of the CVR embedded within the closing price, as each holder of resTORbio stock will receive one contractual CVR immediately prior to the Merger. (2) Each holder of resTORbio common stock as of immediately prior to the completion of the merger was entitled to one CVR issued by resTORbio, subject to and in accordance with the terms and conditions of the CVR Agreement, for each share of resTORbio common stock held by such holder as of immediately prior to the effective time of the Merger (3) Based on the capitalization of resTORbio as of September 15, 2020, 91,309 outstanding unvested resTORbio restricted stock units were accelerated in connection with the merger and holders of the restricted stock units were issued approximately 55,854 shares of resTORbio common stock on a net settlement basis. Similarly, in connection with the merger, vesting of outstanding resTORbio stock options was accelerated in full and the stock options that were not in the in-the-money on the close of the merger were canceled, resulting in approximately 81,370 surviving stock options. The acquisition date fair value of these modified resTORbio restricted stock units and resTORbio stock options attributable to the pre-combination services is included in the estimated purchase price. The Merger was accounted for as a business combination which requires that assets acquired and liabilities assumed be recognized at their fair value as of the acquisition date. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to value the assets acquired and liabilities assumed on the acquisition date, its estimates and assumptions are subject to refinement. Fair value estimates are based on a complex series of judgments about future events and uncertainties and rely heavily on estimates and assumptions. The judgments used to determine the estimated fair value assigned to each class of assets acquired and liabilities assumed, as well as asset lives, can materially impact the Company’s results of operations. The purchase price allocation is preliminary and is subject to change, including for the valuation of intangible assets and contingent consideration, income taxes and related valuation allowances and certain assets and liabilities among other items. The amounts recognized will be finalized as the information necessary to complete the analysis is obtained, but no later than one year after the acquisition date. Any potential adjustments made could be material in relation to the preliminary values presented below. The following summarizes the allocation of the purchase price to the net tangible and intangible assets acquired (in thousands): Net assets acquired: Cash and cash equivalents $ 63,869 Prepaid expenses and other current assets 2,505 Property and equipment 318 IPR&D 3,490 Restricted cash 245 Accounts payable (1,316 ) Accrued and other current liabilities (2,421 ) Other liabilities (40 ) Deferred tax liability (367 ) Goodwill 20,739 Purchase price $ 87,022 The goodwill of $20.7 million is not tax deductible and represents the excess of the consideration paid over the fair value of assets acquired and liabilities assumed. Goodwill is mainly attributable to the enhanced value of the combined company, as reflected in the increase in market value of the resTORbio common shares following the announcement of the Merger with Former Adicet. The fair value of acquired IPR&D related to the research and development of RTB101 for a COVID-19 related indication. The RTB101 compound IPR&D project was valued using an income approach, specifically a projected discounted cash flow method, adjusted for the probability of technical success (“PTS”). The projected discounted cash flow models used to estimate the Company’s IPR&D reflect significant assumptions regarding the estimates a market participant would make in order to evaluate a drug development asset, including the following: - Estimates of potential cash flows to be generated by the project and resulting asset, which was developed utilizing estimates of total patient population, market penetration rates, demand risk adjustment factors, and product pricing; - Estimates regarding the timing of and the expected costs of goods sold, research and development expenses, selling, general and administrative expenses to advance the clinical programs to commercialization, cash flow adjustments and partner profit split; - The projected cash flows were then adjusted using PTS factors that were selected considering both the current state of clinical development and the nature of the proposed indication, (i.e., respiratory therapeutics.); and - Finally, the resulting probability adjusted cash flows were discounted to a present value using a risk-adjusted discount rate, developed considering the market risk present in the forecast and the size of the asset. This IPR&D intangible asset is not amortized, but rather are reviewed for impairment on an annual basis or more frequently if indicators of impairment are present, until the project is completed, abandoned, or transferred to a third party. The contingent consideration for the CVR was valued using an income approach, leveraging the probability adjusted discounted cash flow that would accrue to the combining company and then deducting the administrative fee to be retained by the combined company and other permitted deductions in order to arrive at the net cash expected to be paid out to the CVR holders. The probability adjusted cash flow includes significant estimates and assumptions pertaining to commercialization events and cash consideration received by the Company for the grant of rights to commercialize RTB101 during the term of the CVR Agreement (as discussed above) . These cash flows were then discounted to present value using the same discount rate applied in the valuation of the IPR&D. Transaction costs for the Merger were $2.1 million and $7.1 million for the three month and nine month ended September 30, 2020, respectively and were expensed as incurred in general and administrative expenses in the condensed consolidated statements of operations. The following supplemental unaudited pro forma information represents the Company’s financial results as if the acquisition of resTORbio had occurred on January 1, 2019 (in thousands). For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Revenue $ 3,028 $ (7,047 ) $ 12,493 $ (974 ) Net loss $ (9,791 ) $ (53,794 ) $ (26,424 ) $ (100,142 ) The above unaudited pro forma information was determined based on the historical GAAP results of the Company and resTORbio. The unaudited pro forma consolidated results are not necessarily indicative of what the Company’s consolidated results of operations would have been if the acquisition was completed on January 1, 2019. The unaudited pro forma consolidated net loss includes pro forma adjustments primarily relating to the reclassification of transaction costs and severance payments directly related to the closing of the Merger of $8.6 million from the three months ended September 30, 2020 to the three months ended September 30, 2019 and $15.6 million from the nine months ended September 30, 2020 to the nine months ended September 30, 2019. The unaudited proforma information include proforma adjustments to eliminate the impact of the change in the fair value of redeemable convertible preferred stock tranche liability, TRDF liability, and redeemable convertible warrant liability during the three and nine months ended September 30, 2020 and September 30, 2019 as the redeemable convertible preferred stock tranche liability, TRDF liability, and redeemable convertible warrant liability did not exist once the redeemable convertible preferred stock were converted to common stock in the Merger. The unaudited proforma information also includes proforma adjustments to reclassify stock compensation expense related to the conversion of resTORbio stock options and restricted stock units and the modification of stock option awards to Former Adicet CEO in connection with the Merger to January 1, 2019. Further, stock compensation expense related to resTORbio stock options and restricted stock units recognized in the books of resTORbio prior to the Merger in 2019 and 2020 was reversed in the proforma information. Former Chief Executive Officer’s Transition Agreement On April 28, 2020, in connection with the Merger the Company entered into a transition agreement with Anil Singhal, Former Adicet’s Chief Executive Officer and President, pursuant to which Dr. Singhal transitioned from his role as Chief Executive Officer and President to an advisory role immediately after the closing of the Merger. In accordance with such agreement, Dr. Singhal is entitled to the following compensation: (1) cash payments of (i) $470,000 within 60 days following the closing of the Merger, (ii) an amount equal to his pro-rated bonus of $212,000 for the 2020 calendar year payable within 60 days following the closing of the Merger, (iii) $250,000 payable in one lump sum on January 1, 2021 and (iv) $24,000 payable within 60 days following the closing of the Merger, (2) 12 months’ of accelerated vesting of his unvested options to purchase the Company’s common stock upon completion of the Merger, and (3) a 12-month post-termination exercise period following termination of his independent contractor services agreement, dated April 28, 2020 (the “ICSA”), subject to any earlier expiration of the options to purchase the Company’s common stock by their terms. In addition, Dr. Singhal is entitled to reimbursement of up to $15,000 of his reasonable and documented legal expenses incurred in connection with such transition agreement. Pursuant to such agreement, subject to Dr. Singhal’s continued service through the completion of the Merger and contingent on completion of the Merger, Dr. Singhal’s continued service for purposes of vesting of his options to purchase the Company’s common stock will continue until the earlier of (i) May 7, 2021 or (ii) termination of the ICSA, provided, however, if the ICSA is terminated early without cause, Dr. Singhal is entitled to accelerated vesting of unvested options that would have vested from the date of such termination through May 7, 2021. In addition, Dr. Singhal’s existing options acceleration provisions will terminate. Pursuant to the ICSA, Dr. Singhal will provide certain advisory services to the Company for a term of 12 months following the closing of the merger and is entitled to payments of $12,500 per month for such services.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The Company determines the fair value of financial and non-financial assets and liabilities using the fair Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities. Level 2— 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. 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, 2020 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 10 $ — $ — $ 10 Cash equivalents (1) 10 — — 10 Asset-backed securities — 14,689 — 14,689 Corporate debt securities — 5,722 — 5,722 Commercial paper — 2,749 — 2,749 Marketable debt securities — 23,160 — 23,160 Total fair value of assets $ 10 $ 23,160 $ — $ 23,170 Liabilities: Contingent consideration $ — $ — $ 2,880 2,880 Total fair value of liabilities $ — $ — $ 2,880 $ 2,880 December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 7,232 $ — $ — $ 7,232 Cash equivalents (1) 7,232 — — 7,232 Asset-backed securities — 19,598 — 19,598 Corporate debt securities — 19,394 — 19,394 Commercial paper — 17,892 — 17,892 U.S. Government agency bonds — 5,497 — 5,497 Marketable debt securities — 62,381 — 62,381 Total fair value of assets $ 7,232 $ 62,381 $ — $ 69,613 Liabilities: Redeemable convertible preferred stock warrant liability $ — $ — $ 1,881 1,881 Total fair value of liabilities $ — $ — $ 1,881 $ 1,881 (1) Included in cash and cash equivalents in the condensed consolidated balance sheets The following tables presents a summary of the changes in the fair value of the Company’s Level 3 financial Redeemable Convertible Preferred Stock Tranche Liability TRDF Liability Redeemable Convertible Preferred Stock Warrant Liability Fair value as of December 31, 2018 $ 3,113 $ 142 $ — Recognition of preferred stock warrant liabilities — — 2,131 Change in the fair value included in other income, net (1,970 ) (54 ) (62 ) Settlement — (88 ) — Termination (1,143 ) — — Fair value as of September 30, 2019 $ — $ — $ 2,069 Redeemable Convertible Preferred Stock Warrant Liability Fair value as of December 31, 2019 $ 1,881 Recognition of preferred stock warrant liability 144 Change in the fair value included in other income, net 897 Conversion of convertible preferred stock warrant into common stock warrant in connection with Merger (2,922 ) Fair value as of September 30, 2020 $ — The fair value of the redeemable convertible preferred stock tranche liability, TRDF Liability and the redeemable convertible preferred stock warrant liability is based on significant unobservable inputs, which represent Level 3 measurements within the fair value hierarchy. In determining the fair value of the redeemable convertible preferred stock tranche liability and the redeemable convertible preferred stock warrants, the Company used the Black-Scholes option-pricing model to estimate the fair value using unobservable inputs including the expected term, expected volatility, risk-free interest rate and dividend yield (see Note 14). There were no warrants outstanding for the purchase of redeemable convertible preferred stock as of September 30, 2020, as all such warrants were converted to warrants for the purchase of shares of common stock upon the Merger. The fair value of the TRDF Liability was determined based on fair value of the Company’s Series A redeemable convertible preferred stock. As part of the acquisition of resTORbio, the Company entered into a CVR Agreement and recorded the fair value of the CVR as part of consideration transferred. The Company considers the contingent consideration liability a Level 3 instrument (one with significant unobservable inputs) in the fair value hierarchy (see Note 3).

Marketable Debt Securities

Marketable Debt Securities	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Marketable Debt Securities	5. Marketable Debt Securities The following table summarizes the Company’s marketable debt securities September 30, 2020 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Asset-backed securities $ 14,639 $ — $ 50 $ 14,689 Corporate debt securities 5,700 — 22 5,722 Commercial paper 2,738 — 11 2,749 Total $ 23,077 $ — $ 83 $ 23,160 December 31, 2019 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Asset-backed securities $ 19,589 $ (1 ) $ 10 $ 19,598 Corporate debt securities 19,387 (3 ) 9 19,393 Commercial paper 17,882 — 11 17,893 U.S. Government agency bonds 5,500 (3 ) — 5,497 Total $ 62,358 $ (7 ) $ 30 $ 62,381 The following table summarizes the classification of the Company’s marketable debt securities in the condensed consolidated balance sheets (in thousands): September 30, December 31, 2020 2019 Short-term marketable debt securities 23,160 51,793 Long-term marketable debt securities — 10,588 Total $ 23,160 $ 62,381

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2020
Prepaid Expense And Other Assets Current [Abstract]
Prepaid Expenses and Other Current Assets	6. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): September 30, 2020 December 31, 2019 Prepaid expenses $ 2,416 $ 615 Prepaid insurance 3,353 57 Tax receivable 3,400 722 Interest receivable 67 213 Other current assets 55 179 Total prepaid expenses and other current assets $ 9,291 $ 1,786

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, Net	7. Property and Equipment, net Property and equipment, net consisted of the following (in thousands): Useful life (in years) September 30, 2020 December 31, 2019 Laboratory equipment 3 $ 4,305 $ 3,872 Leasehold improvements Lesser of useful life or lease term $ 1,406 $ 1,327 Furniture and fixtures 3 526 68 Construction in progress — 94 300 Computer equipment 3 91 42 Software 3 170 150 6,592 5,759 Less: Accumulated depreciation and amortization (4,549 ) (3,638 ) Property and equipment, net $ 2,043 $ 2,121 Depreciation and amortization expense was $0.3 million and $0.9 million for the three and nine months ended September 30, 2020, respectively. Depreciation and amortization expense was $0.3million and $1.0 million for three and nine months ended September 30, 2019, respectively.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	8. Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): September 30, 2020 December 31, 2019 Accrued compensation $ 4,455 $ 1,359 Accrued research and development expenses 552 450 Accrued professional services 1,016 301 Accrued other liabilities 826 710 Total accrued and other liabilities $ 6,849 $ 2,820

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2020
Term Loan [Abstract]
Term Loan	9. Term Loan On April 28, 2020, the Company entered into a Loan and Security Agreement with Pacific Western Bank for a term loan not exceeding $12.0 million (the “Loan Agreement”) to finance leasehold improvements for its new corporate headquarters in Redwood City, California and other purposes permitted under the Loan Agreement, with an interest rate equal to the greater of 0.25% above the Prime Rate (as defined in the Loan Agreement) or 5.00%. The Loan Agreement granted to Pacific Western Bank a security interest on substantially all of the Company’s assets other than intellectual property to secure the performance of the Company’s obligations under the Loan Agreement, and contains a variety of affirmative and negative covenants, including required financial reporting, limitations on certain dispositions of assets or distributions, limitations on the incurrence of additional debt or liens and other customary requirements. As of September 30, 2020, the Company was in compliance with such covenants and had no indebtedness outstanding under the Loan Agreement. In connection with the entrance into the Loan Agreement, the Company issued Pacific Western Bank a warrant to purchase shares of its Series B redeemable convertible preferred stock at an exercise price of $1.4034 per share (the “Existing PacWest Warrant”). The Existing PacWest Warrant was initially exercisable for 42,753 shares of the Company’s Series B redeemable convertible preferred stock (not adjusted for the Exchange Ratio) and will be exercisable for an additional number of shares of its Series B redeemable convertible preferred stock equal to 1.00% of the aggregate original principal amount of all term loans made pursuant to the Loan Agreement (up to an aggregate maximum of 128,260 shares of the Company’s Series B redeemable convertible preferred stock (not adjusted for the Exchange Ratio). Pursuant to the terms of the Existing PacWest Warrant and the merger agreement (see Note 3), at the effective time of the merger, the Company issued a new common stock warrant to Pacific Western Bank (the “New PacWest Warrant”) which replaced the Existing PacWest Warrant. The New PacWest Warrant is initially exercisable solely for 5,301 shares of the Company’s common stock will be exercisable for an additional number of shares of the Company’s common stock equal to 1.00% of the aggregate original principal amount of all term loans made pursuant to the Loan Agreement (up to an aggregate maximum of 15,903 shares of the Company’s common stock). Any restriction on the exercise set forth in the Existing PacWest Warrant are in full force and effect in the New PacWest Warrant and the term, exercisability, vesting schedule and other provisions of the Existing PacWest warrant otherwise remain unchanged in the New PacWest Warrant. The Company may request to draw upon the term loan at any time through the date eighteen months after the date of the Loan Agreement (“Availability End Date”), which is October 28, 2021. As of September 30, 2020, no amounts have been drawn under the Loan Agreement. Further, the New PacWest Warrant to purchase 5,301 shares of the Company’s common stock is immediately exercisable. However, none of the warrants have been exercised as of September 30, 2020. At issuance, the Company accounted for the fair value of the Existing PacWest Warrant, determined to be $0.1 million, as a liability and as a corresponding deferred debt issuance cost which was amortized on a straight-line basis until the Availability End Date in interest expenses. The liability was adjusted to fair value each reporting period through earnings. Upon issuance of the New PacWest Warrant, the liability was reclassified to additional paid-in capital and is no longer subject to remeasurement at fair value. The fair value of the New PacWest Warrant was equal to the fair value of the Existing PacWest Warrant on the Merger date. Accordingly, no incremental expense was recognized at the Merger date. Upon each draw of the term loan, the Company will derecognize the proportionate unamortized amount of the deferred asset and account for it as a debt discount to the drawn term loan. The debt discount will be presented in the consolidated balance sheet as a direct adjustment to the carrying value of the term loan. The debt discount will be amortized using the effective interest rate method over the term of the debt and recorded as an interest expense. As of September 30, 2020, the deferred debt issuance costs were $0.2 million and are included in other non-current assets on the Company’s condensed consolidated balance sheets.

Regeneron License and Collabora

Regeneron License and Collaboration Arrangement	9 Months Ended
	Sep. 30, 2020
Revenue Recognition And Deferred Revenue [Abstract]
Regeneron License and Collaboration Arrangement	10. Regeneron License and Collaboration Arrangement Agreement Terms On July 29, 2016, the Company entered into a License and Collaboration Agreement with Regeneron Pharmaceuticals, Inc. (“Regeneron”) to develop engineered immune-cell therapeutics using the universal immune cell therapies platform (the “Regeneron Agreement”). The Company received a non-refundable upfront payment of $25.0 million from Regeneron upon execution of the Regeneron Agreement, and has received an aggregate of $20.0 million of additional payments for research funding from Regeneron under the Regeneron agreement. In addition, Regeneron may have to pay the Company additional amounts in the future consisting of up to an aggregate of $100 million of option exercise fees, in each case as specified in the Regeneron Agreement. Regeneron must also pay the Company high single digit royalties as a percentage of net sales for 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 target generated by the Company through the use of Regeneron’s proprietary mice. The Company must pay Regeneron mid-single to low-double digit 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 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 12 years from first commercial sale. Revenue Recognition For revenue recognition purposes, the Company determined that the duration of the contract is the same as the research term of five (5) years beginning on the execution of the Regeneron Agreement on July 29, 2016. The contract duration is defined as the period during which parties to the contract have present and enforceable rights and obligations. The Company determined that Regeneron faces significant in-substance penalties were it to terminate the Regeneron Agreement prior to the end of the research. At contract inception, the Company determined a transaction price of the Regeneron Agreement consisting of the $25.0 million upfront payment and the aggregate research funding fees payable over the research term. In order to determine the transaction price, the Company evaluated all the payments to be received during the duration of the contract. Per the terms of the original Regeneron Agreement prior to the amendment effective from July 2019, the research funding fees were payable merely due to the passage of time and therefore did not represent a variable consideration. After the amendment became effective in July 2019, certain of these fees became contingent upon meeting certain development and regulatory milestones. Therefore, the Company concluded that after the amendment such potential payments became variable consideration. The receipt of the variable consideration was subject to substantial uncertainty and was therefore excluded from the transaction price upon the effective date of the amendment. As a result, during the three months ended September 30, 2019, the Company recorded $6.6 million as a reduction to cumulative revenue recognized prior to the amendment effective date. The Company will re-evaluate the transaction price if there is a significant change in facts and circumstances at least at the end of each reporting period. The Company increased the transaction price by $10.0 million in June 2020 when it achieved the milestone for the selection of a clinical candidate to the second collaboration target under the Regeneron Agreement, resulting in a recognition of cumulative revenue of $5.0 million during the three months ended June 30, 2020. For the three months ended September 30, 2020 and 2019, the Company recognized $3.0 million and $(7.0) million of license and collaboration revenue, respectively. For the nine months ended September 30, 2020 and 2019, the Company recognized $12.5 million and $(1.0) million of license and collaboration revenue, respectively. The following tables present changes in the Company’s contract liabilities for the three and nine months ended September 30, 2020 and 2019 (in thousands): Nine Months Ended September 30, 2020 Balance at beginning of period Additions Additions (Deductions) (1) Balance at end of period Contract asset $ — $ 10,000 $ (10,000 ) $ — Contract liability $ 21,883 $ 10,000 $ (12,493 ) $ 19,390 Nine Months Ended September 30, 2019 Balance at beginning of period Additions Additions (Deductions) (1) Balance at end of period Contract liability $ 22,878 $ — $ 974 $ 23,852 (1) Contract assets are reflected as accounts receivable—related party on the condensed consolidated balance sheet. The Company achieved the milestone for the selection of a clinical candidate to the second collaboration target under the Regeneron Agreement in June 2020 and was entitled to receive a payment of $10.0 million from Regeneron. The Company received the payment from Regeneron in July 2020. Contract liabilities related to the Regeneron Agreement of $19.4 million and $23.9 million as of September 30, 2020 and 2019, respectively, which was comprised of the $25.0 million upfront payment and additional $5.0 million research funding fees in each of 2017 and 2018, and $10.0 million for achievement of the milestone for the selection of a clinical candidate to the second collaboration target in June 2020, less $25.6 million and $11.1 million of cumulative license and collaboration revenue recognized from the inception of the Regeneron Agreement as of September 30, 2020 and 2019, respectively, and will be recognized as the combined performance obligation is satisfied.

License Funding and Other Agree

License Funding and Other Agreements Related to the CVR	9 Months Ended
	Sep. 30, 2020
License Funding And Other Agreements [Abstract]
License, Funding and Other Agreements Related to the CVR	11. License, Funding and Other Agreements Related to the CVR Novartis License Agreement On March 23, 2017, resTORbio entered into an exclusive license agreement with Novartis International Pharmaceutical Ltd. (“Novartis”). Under the agreement, Novartis granted resTORbio an exclusive, field-restricted, worldwide license, to certain intellectual property rights owned or controlled by Novartis, to develop, commercialize and sell one or more therapeutic products comprising RTB101 or RTB101 in combination with everolimus in a fixed dose combination. The exclusive field under the license agreement is for the treatment, prevention and diagnosis of disease and other conditions in all indications in humans and animals. The agreement may be terminated by either party upon a material breach of obligation by the other party that is not cured with 60 days after written notice. resTORbio may terminate the agreement in its entirety or on a product-by-product or country-by-country basis with or without cause with 60 days’ prior written notice. Novartis may terminate the portion of the agreement related to everolimus if resTORbio fails to use commercially reasonable efforts to research, develop and commercialize a product utilizing everolimus for a period of three years. Novartis may terminate the license agreement upon resTORbio’s bankruptcy, insolvency, dissolution or winding up. As consideration for the license, resTORbio is required to pay up to an aggregate of $4.3 million upon the satisfaction of clinical milestones, up to an aggregate of $24 million upon the satisfaction of regulatory milestones for the first indication approved, and up to an aggregate of $18 million upon the satisfaction of regulatory milestones for the second indication approved. In addition, resTORbio is required to pay up to an aggregate of $125 million upon the satisfaction of commercial milestones, based on the amount of annual net sales. resTORbio is also required to pay tiered royalties ranging from a mid-single digit percentage to a low-teen digit percentage on annual net sales of products. These royalty obligations last on a product-by-product and country-by-country basis until the latest of (i) the expiration of the last valid claim of a Novartis patent covering a subject product, (ii) the expiration of any regulatory exclusivity for the subject product in a country, or (iii) the 10 th As of September 30, 2020, none of the remaining clinical milestones, regulatory milestones, sales milestones, or royalties had been reached or were probable of achievement. National Institute of Health In May 2019, the Company was awarded a 5-year grant for up to $1.5 million from the National Institutes of Health (the “NIH”) to study RTB101 and the regulation of antiviral immunity in the elderly. The Company is entitled to use the award solely to conduct the research. The Company is solely responsible for commencing and conducting the research and will furnish periodic progress updates to the NIH throughout the term of the award. After completing the research, the Company must provide the NIH with a formal report describing the work performed and the results of the research. For funds received under the NIH funding agreement, the Company recognizes a reduction in research and development expenses in an amount equal to the qualifying expenses incurred in each period up to the amount funded by the NIH. Qualifying expenses incurred by the Company in advance of funding by the NIH are recorded in the consolidated balance sheets as other current assets. As of September 30, 2020, $0.7 million qualifying expenses have been incurred and $0.7 million have been funded by the NIH. Contingent Value Rights Agreement In connection with the Merger, the Company entered into a Contingent Value Rights Agreement (the “CVR Agreement”) with Computershare Inc. and Computershare Trust Company, N.A. as joint rights agent. Per the terms of the Merger, each holder of resTORbio common stock as of immediately prior to the completion of the Merger is entitled to one contractual contingent value right (“CVR”), subject to and in accordance with the terms and conditions of the CVR Agreement, for each share of resTORbio common stock held by such holder as of immediately prior to the effective time of the Merger. The CVR holders are entitled to receive net proceeds from the commercialization, if any, received from a third-party commercial partner of RTB101 for a COVID-19 related indication. The total fees and expenses of the Company’s clinical trials for a COVID-19 related indication of RTB101 is limited to $3.0 million under the CVR Agreement.

Commitments and Contingences

Commitments and Contingences	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies Operating Leases The Company recognizes rent expense on a straight-line basis over the lease period. Rent expense recognized under all leases was $0.2 million and $0.6 million for the three months and nine months ended September 30, 2020, respectively. Rent expense recognized under all leases was $0.2 million and $0.5 million for the three months and nine months ended September 30, 2019, respectively. The future minimum lease payments under all non-cancelable operating lease obligations as of September 30, 2020 were as follows (in thousands): 2020 (remaining 3 months) $ 1,018 2021 4,124 2022 3,560 2023 3,428 2024 3,525 2025 and thereafter 17,371 Total $ 33,026 In conjunction with the Menlo Park lease agreement, the Company issued a cash-collateralized letter of credit in lieu of security deposit of $0.2 million. In addition, the Company issued a cash-collateralized letter of credit for $4.1 million in 2018 for the new office lease in Redwood City. The Company also maintains a letter of credit of $0.2 million for the benefit of the landlord in connection with the Company’s office lease in Boston, Massachusetts. All cash amounts are recorded as restricted cash on the condensed consolidated balance sheet as of September 30, 2020 and December 31, 2019. Litigation As of September 30, 2020, five of the seven lawsuits filed against the Company, its directors, Former Adicet, and/or Merger Sub in connection with the Merger had been dismissed. The Company has accrued $0.2 million as of September 30, 2020, for the resolution of claims in connection with the lawsuits. with the Merger, eight putative class action lawsuits have been filed against the Company, its directors, Former Adicet, and Merger Sub.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock (converted to Common Stock)	9 Months Ended
	Sep. 30, 2020
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock (converted to Common Stock)	13. Redeemable Convertible Preferred Stock (converted to Common Stock) As of December 31, 2019, redeemable convertible preferred stock consists of the following (in thousands, except per share and share amounts): Shares Authorized Original Issue Price Shares Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issued Upon Conversion (1) Series A 37,104,185 $ 1.20 37,104,185 $ 35,960 $ 44,525 4,600,920 Series A-1 629,633 1.20 629,633 447 756 78,074 Series A-2 2,428,688 1.20 2,428,688 1,749 2,914 301,157 Series B 59,200,938 1.40 57,004,415 75,927 80,000 7,068,520 99,363,444 97,166,921 $ 114,083 $ 128,195 12,048,671 (1) Adjusted to reflect the Exchange Ratio. Following the closing of the Merger, all outstanding shares of the redeemable convertible preferred stock converted into 12,048,671 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. There were no shares of redeemable convertible preferred stock outstanding as of September 30, 2020.

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants	9 Months Ended
	Sep. 30, 2020
Liabilities And Stockholders Equity [Abstract]
Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants	14. Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants In connection with Series B redeemable convertible preferred stock financing transactions, we issued to our financial advisor warrants to purchase 1,781,387 shares of our Series B redeemable convertible preferred stock at an exercise price of at $1.4034 per share. These warrants will terminate at the earlier of seven-year anniversary from the issuance date and a liquidation of the company. Additionally, in connection with the entrance into the Loan Agreement, the Company issued Pacific Western Bank a warrant to purchase shares of its Series B redeemable convertible preferred stock (see Note 9). These warrants together are referred to as Series B Warrants. Prior to the Merger, the Company classified the Series B Warrants as a liability on its consolidated balance sheet because the warrants are freestanding financial instruments that may have required the Company to transfer assets upon exercise. The liability associated with each of these warrants was initially recorded at fair value upon the issuance date of each warrant and was subsequently remeasured to fair value as a component of other income (expense), net in the consolidated statement of operations and comprehensive loss. Upon the closing of the Merger (see Note 3), pursuant to the Merger Agreement, all of the outstanding redeemable convertible preferred stock was converted to shares of the Company’s common stock and the Series B Warrants converted to warrants for the purchase of the shares of the Company’s common stock. The Company assessed the features of the warrants and determined that they qualify for classification as permanent equity upon the closing of the Merger. Accordingly, the Company remeasured the warrants to fair value upon the closing of the Merger, which was $2.9 million on September 15, 2020. Upon the closing of the Merger, the warrant liability was reclassified to additional paid-in capital. The fair value of the warrants to purchase shares of the Company’s common stock was equal to the fair value of the Series B Warrants on the Merger date. Accordingly, no incremental expense was recognized at the Merger date. The Series B Warrants had a fair value of $1.9 million as of December 31, 2019. The change in fair value of $0.9 million and $0.8 during the three and nine months ended September 30, 2020, respectively, was recorded as a component of other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The change in fair value of $0.1 million and $0.1 during the three and nine months ended September 30, 2019, respectively, was recorded as a component of other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The redeemable convertible preferred stock warrant liability was valued using the following assumptions under the Black-Scholes option-pricing model: September 14, 2020 (Conversion Date) April 28, 2020 (Issuance Date) December 31, 2019 Stock price $ 16.59 $ 11.61 $ 11.32 Expected term (years) 5.86 - 6.62 7.00 6.57 - 6.74 Expected volatility 81.1% - 82.1% 91.17 % 82.1% - 93.3% Risk-free interest rate 0.35% - 0.42% 0.52 % 1.80% - 1.81% Dividend yield 0 % 0 % 0 % The following table provides a roll forward of outstanding warrants: Number of warrants Weighted Average Exercise Price Weighted Average Contractual Term (Years) Outstanding and exercisable warrants to purchase preferred shares as of December 31, 2019 1,781,387 $ 1.4034 6.64 Issued 128,260 Converted to warrants for the purchase of common stock and adjusted for the Exchange Ratio and Reverse Stock Split (1,672,854 ) Outstanding and exercisable warrants to purchase common stock as of September 30, 2020 236,793 $ 11.3177 5.94 As of September 30, 2020, the Company’s outstanding warrants to purchase shares of common stock, including the New PacWest Warrant, consisted of the following: Issuance Date Number of Shares of Common Stock Issuable Exercise Price Classification Expiration Date September 15, 2020 101,610 $ 11.3177 Equity July 25, 2026 September 15, 2020 30,924 $ 11.3177 Equity August 21, 2026 September 15, 2020 77,312 $ 11.3177 Equity September 19, 2026 September 15, 2020 11,044 $ 11.3177 Equity September 26, 2026 September 15, 2020 15,903 $ 11.3177 Equity April 28, 2027 236,793 As of December 31, 2019, the Company’s outstanding warrants to purchase shares of redeemable convertible preferred stock (which converted into warrants to purchase common stock upon close of the Merger) consisted of the following (not adjusted for the Exchange Ratio): Warrant Name Issuance Date Number of Shares of Preferred Stock Issuable Exercise Price Exercisable for Classification Expiration Date Series B warrants July 25, 2019 819,438 $ 1.4034 Series B Liability July 25, 2026 Series B warrants August 21, 2019 249,394 $ 1.4034 Series B Liability August 21, 2026 Series B warrants September 19, 2019 623,486 $ 1.4034 Series B Liability September 19, 2026 Series B warrants September 26, 2019 89,069 $ 1.4034 Series B Liability September 26, 2026 1,781,387

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	15. Stock-based Compensation The Company had reserved common stock for future issuance as follows: September 30, 2020 December 31, 2019 Conversion of redeemable convertible preferred stock (as converted to common stock) — 12,048,671 Conversion of additional authorized and unissued redeemable convertible preferred stock — 51,506 Stock options available for future grant 2,098,174 653,136 Stock options issued and outstanding 3,269,399 1,860,646 Redeemable convertible preferred stock warrants issued and outstanding — 220,890 Common stock warrants issued and outstanding 226,191 — Total 5,593,764 14,834,849 A summary of stock option activity for the nine months ended September 30, 2020 is set forth below: Ongoing Awards Number of Shares Available for Grant Number of Shares Underlying Outstanding Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2019 653,136 1,860,646 $ 4.05 8.53 $ 5,812 Assumed as part of the Merger 2,707,144 81,370 $ 8.39 Options granted (1,517,446 ) 1,713,344 $ 16.06 Options exercised — (123,141 ) $ 1.57 Options forfeited or cancelled 255,340 (262,820 ) $ 4.80 Outstanding, September 30, 2020 2,098,174 3,269,399 $ 10.49 7.73 11,780 Shares exercisable, September 30, 2020 1,195,101 $ 4.20 4.95 9,246 Vested and expected to vest, September 30, 2020 3,269,399 $ 10.49 7.73 11,780 Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Research and development $ 951 $ 54 $ 1,125 $ 191 General and administrative 2,015 337 2,491 674 Total stock-based compensation $ 2,966 $ 391 $ 3,616 $ 865 Summary of Plans Upon completion of the Merger with resTORbio on September 15, 2020, Former Adicet’s 2014 Share Option Plan (the “2014 Plan”), Former Adicet’s 2015 Stock Incentive Plan (the “2015 Plan”), resTORbio’s 2017 Stock Incentive Plan (the “2017 Plan”), resTORbio’s 2018 Stock Incentive Plan (the “2018 Plan”) and resTORbio’s 2018 Employee Stock Purchase Plan (the “2018 ESPP”, and, collectively with the 2014 Plan, the 2015 Plan, the 2017 Plan and the 2018 Plan, the “Plans”) were assumed by the Company. The Plans are administered by the Board of Directors or, at the discretion of the Board of Directors, by a committee of the Board of Directors. No further shares will be issued from the 2014 Plan or 2017 Plan. The exercise prices, vesting and other restrictions are determined at the discretion of the Board of Directors, or its committee if so delegated, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the term of the stock option may not be greater than ten years. Incentive stock options granted to employees and restricted stock awards granted to employees, officers, members of the Board of Directors, advisors, and consultants of the Company typically vest over four years. Non-statutory options granted to employees, officers, members of the Board of Directors, advisors, and consultants of the Company typically vest over three or four years. Shares that are expired, terminated, surrendered or canceled under the Plans without having been fully exercised will be available for future awards. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards. The 2017 Plan and 2018 Plan In 2017, resTORbio adopted the 2017 Plan. In connection with resTORbio’s initial public offering completed in January 2018, the resTORbio Board adopted and resTORbio’s stockholders approved the 2018 Plan. The 2018 Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2019, by 4% of the outstanding number of shares of resTORbio’s common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Board Since the date of effectiveness of the 2018 Plan, resTORbio has not and will not grant any further awards under the 2017 Plan. However, any shares of common stock subject to awards under the 2017 Plan that expire, terminate, or otherwise are surrendered, canceled, forfeited or repurchased without having been fully exercised or resulting in any common stock being issued will become available for issuance under the 2018 Plan. As of September 30, 2020, the number of shares of common stock available for grant under the 2017 and 2018 Plan is 1,462,006. The 2014 Plan and 2015 Plan At the effective time of the Merger, each outstanding and unexercised option to purchase Former Adicet’s common stock, whether vested or unvested, pursuant to the 2015 Plan and a subset of options issued pursuant to the 2014 Plan were converted into options to purchase a number of shares of the Company’s common stock based on the Exchange Ratio. Former Adicet warrants with rights to acquire Former Adicet capital stock were converted into rights to acquire a certain number of shares of the Company’s common stock based on the Exchange Ratio, subject to the terms of and adjustments in the merger agreement. As of September 30, 2020, the number of shares of common stock available for grant under the 2017 and 2018 Plan is 636,168. As of September 30, 2020, an aggregate of 1,677,979 shares of Former Adicet common stock were issuable upon the exercise of outstanding stock options under the 2015 plan at a weighted average exercise price of $6.14 per share and an aggregate of 69,014 shares of Former Adicet common stock were issuable upon the exercise of outstanding stock options under the 2014 Plan at a weighted average exercise price of $1.27 per share. Since the date of effectiveness of the Merger, the Company has not and will not grant any further awards under the 2014 Plan. 2018 Employee Stock Purchase Plan The resTORbio Board adopted and resTORbio’s stockholders approved the 2018 ESPP, which became effective on the date immediately preceding the date on which resTORbio’s registration statement of Form S-1 became effective. The 2018 ESPP enables eligible employees to purchase shares of resTORbio ’s c ommon s tock at a discount. The number of shares of common stock originally reserved for issuance under the 2018 ESPP were 39,290 shares. The 2018 ESPP provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2019 and increasing each January 1 thereafter through January 1, 2028, by the least of (i) 1 % of the outstanding number of shares of resTORbio ’s common stock on the immediately preceding December 31; (ii) 77,703 shares or (iii) such number of shares as determined by the ESPP administrator. On January 1, 2019, as a result of the foregoing evergreen provision, the number of shares of common stock available for issuance under the 2018 ESPP automatically increased from 39,290 to 79,369 shares. On January 1, 2020, as a result of the foregoing evergreen provision, the number of shares of common stock available for issuance under the 2018 ESPP automatically increased from 79,369 to 131,432 shares. No shares have been issued under the 2018 ESPP during the three and six months ended June 30, 2020. Inducement Grant As of September 30, 2020, an aggregate of 195,898 shares of were issuable upon the exercise of inducement grants of stock options approved by the Company in accordance with Nasdaq listing Rule 5635(c)(4) at a weighted average exercise price of $16.11 per share. Former CEO’s Stock Option Modification In connection with the Merger, the stock options granted to Dr. Singhal were modified (refer to Note 3 for details), which resulted in acceleration and recognition of the stock compensation expense of $0.6 million during the quarter ended September 30, 2020. The modification also resulted in incremental stock compensation expense of $0.1 million that will be recognized through May 7, 2021 as the Company determined that Dr. Singhal will be providing substantial services under the Independent Contractor Agreement with Dr. Singhal through that date. Former CEO’s Performance Option On July 14, 2020, the Company’s Board of Directors confirmed that the conditions for Dr. Singhal’s Second Target Milestone Option (as defined in Dr. Singhal’s employment agreement with the Company) had been fulfilled as the Company achieved the milestone for the selection of a clinical candidate to the second collaboration target under the Regeneron Agreement. Following the Merger, on September 17, 2020, the Company’s Board of Directors granted an option to purchase 16,931 shares of the Company’s common stock at an exercise price of $16.11 per share, (i) one-third of the shares vesting on the first anniversary of May 6, 2019, (ii) one-third of the shares vesting in 12 equal monthly installments following such first anniversary, and (iii) one-third of the shares vesting in accordance with the terms of his Transition Agreement. The Company recognized $0.1 million in stock compensation expense associated with this reward during the three months ended September 30, 2020

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss per Share	16. Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders, which excludes unvested restricted shares and shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Net loss attributable to common stockholders $ (14,779 ) $ (14,778 ) $ (27,720 ) $ (21,560 ) Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted 5,208,887 2,149,986 3,190,557 2,133,645 Net loss per share attributable to common stockholder, basic and diluted $ (2.84 ) $ (6.87 ) $ (8.69 ) $ (10.10 ) The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive: As of September 30, 2020 2019 Redeemable convertible preferred stock (as converted to common stock) — 12,048,671 Options to purchase common stock 3,269,399 1,319,600 Redeemable convertible preferred stock warrants — 220,890 Common stock warrants 226,191 — Total 3,495,590 13,589,161

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	17. Income Taxes The Company recorded an income tax benefit of $2.7 million during the nine months ended September 30, 2020. The income tax benefit during the nine months ended September 30, 2020 was generated as a result of the recognition of net operating loss carryback under the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) which was enacted on March 27, 2020 in response to the COVID-19 pandemic and generates a refund of income taxes paid for the year ended December 31, 2017. The Company records the effect of an enacted change in a tax law in the period that includes the enactment date in accordance with ASC 740, Income Taxes The tax relief measures under the CARES Act for businesses include a five-year The Company maintains a full valuation allowance against its deferred tax assets other than a deferred tax liability arising from merger with resTORbio due to the Company’s history of losses as of September 30, 2020. The deferred tax liability recorded relates to the basis difference associated with IPR&D.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	18. Related Party As of September 30, 2020, and December 31, 2019, Regeneron owned 883,568 shares of the Company’s common stock, respectively. Regeneron became a related party in July 2019 as a result of Series B redeemable convertible preferred stock financing. For the three and nine months ended September 30, 2020 and 2019, the Company recorded revenue of $3.0 million, $12.5 million, $(7.0) million and $(1.0) million, respectively, and as of September 30, 2020, the Company recorded accounts receivable of $0 and deferred revenue of $19.4 million related to the Regeneron Agreement. See Note 10 for a discussion of the Regeneron Agreement.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Event	19. Subsequent Events On October 22, 2020, the U.S. Food and Drug Administration cleared the Company’s Investigational New Drug (“IND”) application for ADI-001, an allogeneic gamma delta T cell therapy expressing a chimeric antigen receptor (“CAR”) targeting CD20 for treatment of non-Hodgkin’s lymphoma (“NHL”). The active IND enables the Company to initiate the first-in-human clinical trial to assess safety and efficacy of ADI-001 in NHL patients.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited interim condensed consolidated financial statements and related disclosures have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
Principles of Consolidation	Principles of Consolidation The interim condensed consolidated financial statements include the accounts of the Company and its
Reverse Stock Split	Reverse Stock Split On September 15, 2020, immediately before the closing of the Merger, resTORbio effected a
Unaudited Interim Financial Information	Unaudited Interim Financial Information The condensed consolidated balance sheet as of December 31, 2019 was derived from the Company’s audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited condensed consolidated financial statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019, have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”), for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with 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 condensed 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, 2019 included in the Company’s Current Report on Form 8-K filed with the Securities and Exchange Commission on September 16, 2020. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s condensed consolidated financial position as of September 30, 2020 and condensed consolidated results of operations for the three and nine months ended September 30, 2020 and 2019 and condensed consolidated cash flows for the nine months ended September 30, 2020 and 2019 have been made. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2020.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements as well as the reported amounts of revenues and expenses during the reporting period. Such estimates include the valuation of the intangible assets acquired in business combinations, redeemable convertible preferred stock warrant liability, redeemable convertible preferred stock tranche liability, the Technion Research and Development Foundation liability (“TRDF Liability”), contingent consideration liability for contingent value right (“CVR”), deferred tax assets, useful lives of property and equipment, accruals for research and development activities, revenue recognition and stock-based compensation. Actual results could differ from those estimates. The current COVID-19 (coronavirus) pandemic, which is impacting worldwide economic activity, poses risk that the Company or its employees, contractors, suppliers, and other partners may be prevented from conducting business activities for an indefinite period of time, including due to shutdowns that may be requested or mandated by governmental authorities. The extent to which the coronavirus impacts the Company’s operations will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration of the outbreak, new information that will emerge concerning the severity of the coronavirus and the actions to contain the coronavirus or treat its impact, among others. COVID-19 may impact the timing of regulatory approval of the INDs for clinical trials, the enrollment of any clinical trials that are approved, the availability of clinical trial materials and regulatory approval and commercialization of our products. COVID-19 may also impact the Company’s ability to access capital, which could negatively impact short-term and long-term liquidity.
Business Combinations	Business Combinations Business combinations are accounted for under the acquisition method. The Company recognizes the assets acquired and liabilities assumed in business combinations on the basis of their fair values at the date of acquisition. The Company assesses the fair value of assets acquired, including intangible assets, and liabilities assumed using a variety of methods. Each asset acquired and liability assumed is measured at fair value from the perspective of a market participant. The method used to estimate the fair values of intangible assets incorporates significant estimates and assumptions regarding the estimates a market participant would make in order to evaluate an asset, including a market participant’s use of the asset, future cash inflows and outflows, probabilities of success, asset lives, and the appropriate discount rates. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. Any excess purchase price over the fair value of the net tangible and intangible assets acquired is allocated to goodwill. Transaction costs and restructuring costs associated with a business combination are expensed as incurred. During the measurement period, which extends no later than one year from the acquisition date, the Company may record certain adjustments to the carrying value of the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, all adjustments are recorded in the condensed consolidated statements of operations as operating expenses or income.
Contingent Consideration Liability	Contingent Consideration Liability The estimated fair value of contingent consideration liability, initially measured and recorded on the acquisition date, is considered to be a Level 3 instrument. The contingent consideration liability is recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in research and development expenses in the condensed consolidated statements of operations.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the fair value of net tangible and identified intangible assets acquired in a business combination. Goodwill is not amortized but is evaluated at least annually for impairment or when a change in facts and circumstances indicate that the fair value of the goodwill may be below its carrying value. Goodwill is tested for impairment at the reporting unit level annually in the fourth quarter, or more frequently when events or changes in circumstances indicate that the asset might be impaired. Examples of such events or circumstances include, but are not limited to, a significant adverse change in legal or business climate, an adverse regulatory action or unanticipated competition. The Company has determined that it operates in a single operating segment and has a single reporting unit. Prior to performing the impairment test, t he Company assesses qualitative factors to determine whether the existence of events or circumstances would indicate that it is more likely than not that the fair value of the reporting unit was less than its carrying amount. If after assessing the totality of events or circumstances, the Company were to determine that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, then the Company would perform a quantitative impairment test. The quantitative impairment test involves comparing the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets, goodwill is not impaired, and no further testing is required. If the fair value of the reporting unit is less than the carrying value, the Company measures the amount of impairment loss, if any, as the excess of the carrying value over the fair value of the reporting unit. The Company has determined there were no indicators of goodwill impairment as of September 30, 2020.
Intangible Assets	Intangible Assets In connection with the Merger, the Company acquired certain IPR&D assets, which were classified as indefinite-lived intangible assets. Acquired IPR&D represents the fair value assigned to research and development assets that the Company acquires and have not been completed at the acquisition date. The fair value of IPR&D acquired in a business combination is recorded on the Company’s condensed consolidated balance sheets at the acquisition-date fair value and is determined by estimating the costs to develop the technology into commercially viable products, estimating the resulting revenue from the products, and discounting the projected net cash flows to present value. IPR&D is not amortized, but rather is reviewed for impairment on an annual basis or more frequently if indicators of impairment are present, until the project is completed, abandoned, or transferred to a third party.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB ASC or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Recently Adopted Accounting Pronouncements In August 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Recently Issued Accounting Pronouncements In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848)

Business Combination (Tables)

Business Combination (Tables)	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Schedule of Summarizes the Purchase Price in the Merger	The following summarizes the purchase price in the Merger (in thousands, except share and per share amounts): Fair value of common stock shares of the combined company owned by resTORbio stockholders (1) $ 83,516 Fair value of contingent consideration liability with respect to CVR (2) 2,880 Estimated fair value of modified stock options and restricted stock units attributable to pre-combination services (3) 626 Purchase price $ 87,022
Schedule of Estimated Share Consideration of Combined Company	(1) Represents the share consideration of the combined company that the resTORbio stockholders own as of the closing of the merger calculated as follows: Number of shares of the combined company owned by resTORbio stockholders (a) 5,207,695 Multiplied by the fair value per share of resTORbio common $ 16.59 Acquisition date fair value of resTORbio 86,396 Less: portion of the fair value to be distributed as CVR (c) (2,880 ) Fair value of shares of the combined company owned by resTORbio stockholders $ 83,516
Schedule of Summarizes the Allocation of the Purchase Price to the Net Tangible and Intangible Assets Acquired	The following summarizes the allocation of the purchase price to the net tangible and intangible assets acquired (in thousands): Net assets acquired: Cash and cash equivalents $ 63,869 Prepaid expenses and other current assets 2,505 Property and equipment 318 IPR&D 3,490 Restricted cash 245 Accounts payable (1,316 ) Accrued and other current liabilities (2,421 ) Other liabilities (40 ) Deferred tax liability (367 ) Goodwill 20,739 Purchase price $ 87,022
Schedule of Supplemental Unaudited Pro Forma Information	The following supplemental unaudited pro forma information represents the Company’s financial results as if the acquisition of resTORbio had occurred on January 1, 2019 (in thousands). For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 2020 2019 Revenue $ 3,028 $ (7,047 ) $ 12,493 $ (974 ) Net loss $ (9,791 ) $ (53,794 ) $ (26,424 ) $ (100,142 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured on Recurring Basis	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, 2020 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 10 $ — $ — $ 10 Cash equivalents (1) 10 — — 10 Asset-backed securities — 14,689 — 14,689 Corporate debt securities — 5,722 — 5,722 Commercial paper — 2,749 — 2,749 Marketable debt securities — 23,160 — 23,160 Total fair value of assets $ 10 $ 23,160 $ — $ 23,170 Liabilities: Contingent consideration $ — $ — $ 2,880 2,880 Total fair value of liabilities $ — $ — $ 2,880 $ 2,880 December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds $ 7,232 $ — $ — $ 7,232 Cash equivalents (1) 7,232 — — 7,232 Asset-backed securities — 19,598 — 19,598 Corporate debt securities — 19,394 — 19,394 Commercial paper — 17,892 — 17,892 U.S. Government agency bonds — 5,497 — 5,497 Marketable debt securities — 62,381 — 62,381 Total fair value of assets $ 7,232 $ 62,381 $ — $ 69,613 Liabilities: Redeemable convertible preferred stock warrant liability $ — $ — $ 1,881 1,881 Total fair value of liabilities $ — $ — $ 1,881 $ 1,881 (1) Included in cash and cash equivalents in the condensed consolidated balance sheets
Schedule of Changes in Fair Value of Level 3 Financial Instruments	The following tables presents a summary of the changes in the fair value of the Company’s Level 3 financial Redeemable Convertible Preferred Stock Tranche Liability TRDF Liability Redeemable Convertible Preferred Stock Warrant Liability Fair value as of December 31, 2018 $ 3,113 $ 142 $ — Recognition of preferred stock warrant liabilities — — 2,131 Change in the fair value included in other income, net (1,970 ) (54 ) (62 ) Settlement — (88 ) — Termination (1,143 ) — — Fair value as of September 30, 2019 $ — $ — $ 2,069 Redeemable Convertible Preferred Stock Warrant Liability Fair value as of December 31, 2019 $ 1,881 Recognition of preferred stock warrant liability 144 Change in the fair value included in other income, net 897 Conversion of convertible preferred stock warrant into common stock warrant in connection with Merger (2,922 ) Fair value as of September 30, 2020 $ —

Marketable Debt Securities (Tab

Marketable Debt Securities (Tables)	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Schedule of Marketable Debt Securities	The following table summarizes the Company’s marketable debt securities September 30, 2020 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Asset-backed securities $ 14,639 $ — $ 50 $ 14,689 Corporate debt securities 5,700 — 22 5,722 Commercial paper 2,738 — 11 2,749 Total $ 23,077 $ — $ 83 $ 23,160 December 31, 2019 Amortized Cost Unrealized Losses Unrealized Gains Fair Value Asset-backed securities $ 19,589 $ (1 ) $ 10 $ 19,598 Corporate debt securities 19,387 (3 ) 9 19,393 Commercial paper 17,882 — 11 17,893 U.S. Government agency bonds 5,500 (3 ) — 5,497 Total $ 62,358 $ (7 ) $ 30 $ 62,381
Summary of Classification of Marketable Debt Securities in Condensed Consolidated Balance Sheets	The following table summarizes the classification of the Company’s marketable debt securities in the condensed consolidated balance sheets (in thousands): September 30, December 31, 2020 2019 Short-term marketable debt securities 23,160 51,793 Long-term marketable debt securities — 10,588 Total $ 23,160 $ 62,381

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 December 31, 2019 Prepaid expenses $ 2,416 $ 615 Prepaid insurance 3,353 57 Tax receivable 3,400 722 Interest receivable 67 213 Other current assets 55 179 Total prepaid expenses and other current assets $ 9,291 $ 1,786

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): Useful life (in years) September 30, 2020 December 31, 2019 Laboratory equipment 3 $ 4,305 $ 3,872 Leasehold improvements Lesser of useful life or lease term $ 1,406 $ 1,327 Furniture and fixtures 3 526 68 Construction in progress — 94 300 Computer equipment 3 91 42 Software 3 170 150 6,592 5,759 Less: Accumulated depreciation and amortization (4,549 ) (3,638 ) Property and equipment, net $ 2,043 $ 2,121

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Summary of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): September 30, 2020 December 31, 2019 Accrued compensation $ 4,455 $ 1,359 Accrued research and development expenses 552 450 Accrued professional services 1,016 301 Accrued other liabilities 826 710 Total accrued and other liabilities $ 6,849 $ 2,820

Regeneron License and Collabo_2

Regeneron License and Collaboration Arrangement (Tables)	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Change in Company's Contract Liabilities	The following tables present changes in the Company’s contract liabilities for the three and nine months ended September 30, 2020 and 2019 (in thousands): Nine Months Ended September 30, 2020 Balance at beginning of period Additions Additions (Deductions) (1) Balance at end of period Contract asset $ — $ 10,000 $ (10,000 ) $ — Contract liability $ 21,883 $ 10,000 $ (12,493 ) $ 19,390 Nine Months Ended September 30, 2019 Balance at beginning of period Additions Additions (Deductions) (1) Balance at end of period Contract liability $ 22,878 $ — $ 974 $ 23,852 (1)

Commitments and Contingences (T

Commitments and Contingences (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule Of Future Minimum Rental Payments For Operating Leases	The future minimum lease payments under all non-cancelable operating lease obligations as of September 30, 2020 were as follows (in thousands): 2020 (remaining 3 months) $ 1,018 2021 4,124 2022 3,560 2023 3,428 2024 3,525 2025 and thereafter 17,371 Total $ 33,026

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock (converted to Common Stock) (Tables)	9 Months Ended
	Sep. 30, 2020
Temporary Equity Disclosure [Abstract]
Summary of Redeemable Convertible Preferred Stock	As of December 31, 2019, redeemable convertible preferred stock consists of the following (in thousands, except per share and share amounts): Shares Authorized Original Issue Price Shares Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issued Upon Conversion (1) Series A 37,104,185 $ 1.20 37,104,185 $ 35,960 $ 44,525 4,600,920 Series A-1 629,633 1.20 629,633 447 756 78,074 Series A-2 2,428,688 1.20 2,428,688 1,749 2,914 301,157 Series B 59,200,938 1.40 57,004,415 75,927 80,000 7,068,520 99,363,444 97,166,921 $ 114,083 $ 128,195 12,048,671 (1) Adjusted to reflect the Exchange Ratio.

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants (Tables)	9 Months Ended
	Sep. 30, 2020
Liabilities And Stockholders Equity [Abstract]
Schedule of Redeemable Convertible Preferred Stock Warrant Liability using Black-Scholes Option-Pricing Model	The redeemable convertible preferred stock warrant liability was valued using the following assumptions under the Black-Scholes option-pricing model: September 14, 2020 (Conversion Date) April 28, 2020 (Issuance Date) December 31, 2019 Stock price $ 16.59 $ 11.61 $ 11.32 Expected term (years) 5.86 - 6.62 7.00 6.57 - 6.74 Expected volatility 81.1% - 82.1% 91.17 % 82.1% - 93.3% Risk-free interest rate 0.35% - 0.42% 0.52 % 1.80% - 1.81% Dividend yield 0 % 0 % 0 %
Schedule of Outstanding Warrants	The following table provides a roll forward of outstanding warrants: Number of warrants Weighted Average Exercise Price Weighted Average Contractual Term (Years) Outstanding and exercisable warrants to purchase preferred shares as of December 31, 2019 1,781,387 $ 1.4034 6.64 Issued 128,260 Converted to warrants for the purchase of common stock and adjusted for the Exchange Ratio and Reverse Stock Split (1,672,854 ) Outstanding and exercisable warrants to purchase common stock as of September 30, 2020 236,793 $ 11.3177 5.94
Schedule of Outstanding Warrants to Purchase Shares of Common Stock	As of September 30, 2020, the Company’s outstanding warrants to purchase shares of common stock, including the New PacWest Warrant, consisted of the following: Issuance Date Number of Shares of Common Stock Issuable Exercise Price Classification Expiration Date September 15, 2020 101,610 $ 11.3177 Equity July 25, 2026 September 15, 2020 30,924 $ 11.3177 Equity August 21, 2026 September 15, 2020 77,312 $ 11.3177 Equity September 19, 2026 September 15, 2020 11,044 $ 11.3177 Equity September 26, 2026 September 15, 2020 15,903 $ 11.3177 Equity April 28, 2027 236,793
Schedule of Outstanding Warrants to Purchase Shares of Redeemable Convertible Preferred Stock	As of December 31, 2019, the Company’s outstanding warrants to purchase shares of redeemable convertible preferred stock (which converted into warrants to purchase common stock upon close of the Merger) consisted of the following (not adjusted for the Exchange Ratio): Warrant Name Issuance Date Number of Shares of Preferred Stock Issuable Exercise Price Exercisable for Classification Expiration Date Series B warrants July 25, 2019 819,438 $ 1.4034 Series B Liability July 25, 2026 Series B warrants August 21, 2019 249,394 $ 1.4034 Series B Liability August 21, 2026 Series B warrants September 19, 2019 623,486 $ 1.4034 Series B Liability September 19, 2026 Series B warrants September 26, 2019 89,069 $ 1.4034 Series B Liability September 26, 2026 1,781,387

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Number of Shares of Common Stock Reserved for Future Issuance	The Company had reserved common stock for future issuance as follows: September 30, 2020 December 31, 2019 Conversion of redeemable convertible preferred stock (as converted to common stock) — 12,048,671 Conversion of additional authorized and unissued redeemable convertible preferred stock — 51,506 Stock options available for future grant 2,098,174 653,136 Stock options issued and outstanding 3,269,399 1,860,646 Redeemable convertible preferred stock warrants issued and outstanding — 220,890 Common stock warrants issued and outstanding 226,191 — Total 5,593,764 14,834,849
Summary of Stock Option Activity	A summary of stock option activity for the nine months ended September 30, 2020 is set forth below: Ongoing Awards Number of Shares Available for Grant Number of Shares Underlying Outstanding Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding, December 31, 2019 653,136 1,860,646 $ 4.05 8.53 $ 5,812 Assumed as part of the Merger 2,707,144 81,370 $ 8.39 Options granted (1,517,446 ) 1,713,344 $ 16.06 Options exercised — (123,141 ) $ 1.57 Options forfeited or cancelled 255,340 (262,820 ) $ 4.80 Outstanding, September 30, 2020 2,098,174 3,269,399 $ 10.49 7.73 11,780 Shares exercisable, September 30, 2020 1,195,101 $ 4.20 4.95 9,246 Vested and expected to vest, September 30, 2020 3,269,399 $ 10.49 7.73 11,780
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, 2020 2019 2020 2019 Research and development $ 951 $ 54 $ 1,125 $ 191 General and administrative 2,015 337 2,491 674 Total stock-based compensation $ 2,966 $ 391 $ 3,616 $ 865

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
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 attributable to common stockholders, which excludes unvested restricted shares and shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Net loss attributable to common stockholders $ (14,779 ) $ (14,778 ) $ (27,720 ) $ (21,560 ) Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted 5,208,887 2,149,986 3,190,557 2,133,645 Net loss per share attributable to common stockholder, basic and diluted $ (2.84 ) $ (6.87 ) $ (8.69 ) $ (10.10 )
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 attributable to common stockholders for the period presented because including them would have been antidilutive: As of September 30, 2020 2019 Redeemable convertible preferred stock (as converted to common stock) — 12,048,671 Options to purchase common stock 3,269,399 1,319,600 Redeemable convertible preferred stock warrants — 220,890 Common stock warrants 226,191 — Total 3,495,590 13,589,161

Organization and Nature of the

Organization and Nature of the Business - Additional Information (Details) $ in Thousands	Sep. 15, 2020	Sep. 15, 2020	Sep. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)shares
Schedule Of Equity Method Investments [Line Items]
Entity incorporation date			Nov. 30, 2014
Entity date of merger			Apr. 28, 2020
Equity method investment, Ownership percentage			25.00%
Reverse stock split	1-for-7	1-for-7
Exchange ratio	0.1240
Common stock, shares outstanding | shares			19,589,637	2,155,578
Accumulated deficit			$ (97,367)	$ (69,647)
Adicet Therapeutics [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment, Ownership percentage			75.00%
Common stock, shares outstanding | shares			19,589,828
Cash, cash equivalents and marketable securities			$ 108,100
Accumulated deficit			$ 97,400

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	Sep. 15, 2020shares	Sep. 15, 2020	Sep. 30, 2020USD ($)
Accounting Policies [Abstract]
Reverse stock split	1-for-7	1-for-7
Fractional shares for reverse stock split ratio | shares	0
Reverse stock split exchange ratio	0.1240
Goodwill impairment | $			$ 0

Business Combination - Addition

Business Combination - Additional Information (Details) $ in Thousands	Sep. 15, 2020shares	Sep. 15, 2020shares	Apr. 28, 2020USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Business Acquisition [Line Items]
Reverse stock split exchange ratio		0.1240
Percentage of outstanding capital stock	75.00%	75.00%
Reverse stock split	1-for-7	1-for-7
Goodwill				$ 20,739		$ 20,739
Transition Agreement [Member]
Business Acquisition [Line Items]
Amount equal to pro-rated bonus			$ 212,000
Lump sum payable			250,000
Payable upon closing of merger			24,000
Legal fees			15,000
Advisory services annual fee			12,500
resTORbio
Business Acquisition [Line Items]
Reverse stock split exchange ratio		0.1240
Number of shares of surviving stock options | shares		81,370
Unvested restricted stock units outstanding | shares	91,309	91,309
Common stock share issued on a net settlement basis | shares		55,854
Goodwill				20,739		20,739
Transaction cost for merger				2,100		7,100
Transaction cost for business acquisition				$ 8,600	$ 8,600	$ 15,600	$ 15,600
resTORbio | Transition Agreement [Member]
Business Acquisition [Line Items]
Cash payment			$ 470,000
Expiration period closing of the merger			60 days
resTORbio | Common Stock
Business Acquisition [Line Items]
Percentage of outstanding capital stock	25.00%	25.00%

Business Combination - Schedule

Business Combination - Schedule of Summarizes the Purchase Price in the Merger (Details) - USD ($) $ in Thousands	Sep. 15, 2020	Sep. 30, 2020
Business Acquisition [Line Items]
Contingent consideration liability		$ 2,880
resTORbio
Business Acquisition [Line Items]
Fair value of common stock shares of the combined company owned by resTORbio stockholders	$ 83,516
Contingent consideration liability	2,880
Estimated fair value of modified stock options and restricted stock units attributable to pre-combination services	626
Purchase price	$ 87,022

Business Combination - Schedu_2

Business Combination - Schedule of Estimated Share Consideration of Combined Company (Details) - resTORbio $ / shares in Units, $ in Thousands	Sep. 15, 2020USD ($)$ / sharesshares
Business Acquisition [Line Items]
Number of shares of the combined company owned by resTORbio stockholders | shares	5,207,695
Multiplied by the fair value per share of resTORbio common stock | $ / shares	$ 16.59
Acquisition date fair value of resTORbio	$ 86,396
Less: portion of the fair value to be distributed as CVR	(2,880)
Fair value of common stock shares of the combined company owned by resTORbio stockholders	$ 83,516

Business Combination - Schedu_3

Business Combination - Schedule of Estimated Share Consideration of Combined Company (Parenthetical) (Details)	Sep. 15, 2020shares
resTORbio
Business Acquisition [Line Items]
Number of shares of the combined company owned by resTORbio stockholders	5,207,695

Business Combination - Schedu_4

Business Combination - Schedule of Summarizes the Purchase Price in the Merger (Parenthetical) (Details) - resTORbio	Sep. 15, 2020shares
Business Acquisition [Line Items]
Unvested restricted stock units outstanding	91,309
Common stock share issued on a net settlement basis	55,854
Number of shares of surviving stock options	81,370

Business Combination - Schedu_5

Business Combination - Schedule of Summarizes the Allocation of the Purchase Price to the Net Tangible and Intangible Assets Acquired (Details) $ in Thousands	Sep. 30, 2020USD ($)
Net assets acquired:
Goodwill	$ 20,739
resTORbio
Net assets acquired:
Cash and cash equivalents	63,869
Prepaid expenses and other current assets	2,505
Property and equipment	318
IPR&D	3,490
Restricted cash	245
Accounts payable	(1,316)
Accrued and other current liabilities	(2,421)
Other liabilities	(40)
Deferred tax liability	(367)
Goodwill	20,739
Purchase price	$ 87,022

Business Combination - Schedu_6

Business Combination - Schedule of Supplemental Unaudited Pro Forma Information (Details) - resTORbio - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Revenue	$ 3,028	$ (7,047)	$ 12,493	$ (974)
Net loss	$ (9,791)	$ (53,794)	$ (26,424)	$ (100,142)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	$ 23,170	$ 69,613
Total fair value of liabilities	2,880	1,881
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	10	7,232
Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	10	7,232
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	2,749	17,892
Fair Value Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	10	7,232
Fair Value Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	10	7,232
Fair Value Level 1 | Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	10	7,232
Fair Value Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	23,160	62,381
Fair Value Level 2 | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	2,749	17,892
Fair Value Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of liabilities	2,880	1,881
Asset Backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	14,689	19,598
Asset Backed Securities | Fair Value Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	14,689	19,598
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	5,722	19,394
Corporate Debt Securities | Fair Value Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	5,722	19,394
Marketable Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	23,160	62,381
Marketable Securities | Fair Value Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets	23,160	62,381
Contingent Consideration [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of liabilities	2,880
Contingent Consideration [Member] | Fair Value Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of liabilities	$ 2,880
US Government Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		5,497
US Government Agency Bonds | Fair Value Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of assets		5,497
Redeemable Convertible Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of liabilities		1,881
Redeemable Convertible Preferred Stock Warrant Liability | Fair Value Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of liabilities		$ 1,881

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Changes in Fair Value of Level 3 Financial Instruments (Details) - Fair Value Level 3 - Measure of Changes in Fair Value - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Redeemable Convertible Preferred Stock Tranche Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance		$ 3,113
Recognition of preferred stock warrant liabilities		0
Change in the fair value included in other income, net		(1,970)
Settlement		0
Termination		(1,143)
Fair value, ending balance		0
TRDF Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance		142
Recognition of preferred stock warrant liabilities		0
Change in the fair value included in other income, net		(54)
Settlement		(88)
Termination		0
Fair value, ending balance		0
Redeemable Convertible Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, beginning balance	$ 1,881	0
Recognition of preferred stock warrant liabilities	144	2,131
Change in the fair value included in other income, net	897	(62)
Settlement		0
Termination		0
Fair value, ending balance	0	$ 2,069
Conversion of convertible preferred stock warrant into common stock warrant in connection with Merger	$ (2,922)

Marketable Debt Securities - Sc

Marketable Debt Securities - Schedule of Marketable Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Amortized Cost	$ 23,077	$ 62,358
Unrealized Losses		(7)
Unrealized Gains	83	30
Fair Value	23,160	62,381
Asset Backed Securities
Marketable Securities [Line Items]
Amortized Cost	14,639	19,589
Unrealized Losses		(1)
Unrealized Gains	50	10
Fair Value	14,689	19,598
Corporate Debt Securities
Marketable Securities [Line Items]
Amortized Cost	5,700	19,387
Unrealized Losses		(3)
Unrealized Gains	22	9
Fair Value	5,722	19,393
Commercial Paper
Marketable Securities [Line Items]
Amortized Cost	2,738	17,882
Unrealized Gains	11	11
Fair Value	$ 2,749	17,893
US Government Agency Bonds
Marketable Securities [Line Items]
Amortized Cost		5,500
Unrealized Losses		(3)
Fair Value		$ 5,497

Marketable Debt Securities - Su

Marketable Debt Securities - Summary of Classification of Marketable Debt Securities in Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Short-term marketable debt securities	$ 23,160	$ 51,793
Long-term marketable debt securities		10,588
Marketable debt securities	$ 23,160	$ 62,381

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, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 2,416	$ 615
Prepaid insurance	3,353	57
Tax receivable	3,400	722
Interest receivable	67	213
Other current assets	55	179
Total prepaid expenses and other current assets	$ 9,291	$ 1,786

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 6,592	$ 5,759
Less: Accumulated depreciation and amortization	(4,549)	(3,638)
Property and equipment, net	2,043	2,121
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 4,305	3,872
Useful life (in years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,406	1,327
Useful life (in years)	Lesser of useful life or lease term
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 526	68
Useful life (in years)	3 years
Construction In Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 94	300
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 91	42
Useful life (in years)	3 years
Software
Property Plant And Equipment [Line Items]
Total property and equipment	$ 170	$ 150
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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 300	$ 300	$ 911	$ 962

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Summary of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued compensation	$ 4,455	$ 1,359
Accrued research and development expenses	552	450
Accrued professional services	1,016	301
Accrued other liabilities	826	710
Total accrued and other liabilities	$ 6,849	$ 2,820

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Apr. 28, 2020	Dec. 31, 2019
Class Of Warrant Or Right [Line Items]
Warrant exercise price	$ 11.3177		$ 1.4034
Loan availability end date	Oct. 28, 2021
Loan amount drawn	$ 0
Number of warrants exercised	$ 0
Deferred debt issuance cost	$ 100,000
Incremental expense	0
Debt issuance costs, gross	$ 200,000
Common Stock
Class Of Warrant Or Right [Line Items]
Number of securities called		5,301
Series B Convertible Preferred Stock [ Member ]
Class Of Warrant Or Right [Line Items]
Warrant exercise price		$ 1.4034
Number of securities called		42,753
Maximum
Class Of Warrant Or Right [Line Items]
Term loan to finance leasehold improvements		$ 12,000,000
Maximum | Common Stock
Class Of Warrant Or Right [Line Items]
Number of additional securities called		15,903
Maximum | Series B Convertible Preferred Stock [ Member ]
Class Of Warrant Or Right [Line Items]
Number of additional securities called		128,260
Minimum | Prime Rate
Class Of Warrant Or Right [Line Items]
Interest rate for term loan to finance leasehold improvements		0.25%

Regeneron License and Collabo_3

Regeneron License and Collaboration Arrangement - Additional Information (Details) - Regeneron Pharmaceuticals, Inc. - USD ($) $ in Millions	Jul. 29, 2016	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non refundable upfront payment received	$ 25
Additional payment for research funding received	$ 20							$ 5	$ 5
License agreement termination description	12 years
Contract research term period	5 years
Upfront payment	$ 25					$ 25
Licence agreement cumulative revenue recognised			$ 5		$ 10	25.6	$ 11.1
License agreement cumulative revenue reduction recognised				$ 6.6
Increase in estimated transaction price			$ 10
License and collaboration revenue		$ 3		$ (7)		12.5	(1)
Contract liability						$ 19.4	$ 23.9
Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Licence agreement additional amount payable of option exercise fees	$ 100

Regeneron License and Collabo_4

Regeneron License and Collaboration Arrangement - Summary of Change in Company's Contract Liabilities (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019
Contract Asset
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Additions		$ 10,000
Additions (Deductions)	[1]	(10,000)
Contract Liability
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at beginning of period		21,883	$ 22,878
Additions		10,000
Additions (Deductions)	[1]	(12,493)	974
Balance at end of period		$ 19,390	$ 23,852
[1]	Additions (deductions) to contract liabilities relate to deferred revenue derecognized (recognized) as revenue during the reporting period.

License Funding and Other Agr_2

License Funding and Other Agreements Related to the CVR - Additional Information (Details) $ in Millions	1 Months Ended	9 Months Ended
	May 31, 2019USD ($)	Sep. 30, 2020USD ($)Right	Mar. 23, 2017USD ($)
National Institute of Health
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant term	5 years
Grants receivable	$ 1.5
Qualifying expenses		$ 0.7
National Institute of Health | Funding Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Qualifying expenses		$ 0.7
Novartis License Agreement | Novartis International Pharmaceutical Ltd.
Research And Development Arrangement Contract To Perform For Others [Line Items]
License agreement termination description		The agreement may be terminated by either party upon a material breach of obligation by the other party that is not cured with 60 days after written notice. resTORbio may terminate the agreement in its entirety or on a product-by-product or country-by-country basis with or without cause with 60 days’ prior written notice.
Novartis License Agreement | Novartis International Pharmaceutical Ltd. | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Aggregate amount payable upon satisfaction of clinical milestones			$ 4.3
Aggregate amount payable upon satisfaction of regulatory milestones for first indication approved			24
Aggregate amount payable upon satisfaction of regulatory milestones for second indication approved			18
Aggregate amount payable upon satisfaction of commercial milestones			$ 125
Contingent Value Rights Agreement [Member] | COVID-19 [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Common stock value right | Right		1
Total fees and expenses related to clinical trials		$ 3

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)Lawsuit	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Long Term Purchase Commitment [Line Items]
Lease payments	$ 0.2	$ 0.2	$ 0.6	$ 0.5
Lawsuits Filed Against Company | Lawsuit			5
Litigation settlement expense			$ 0.2
Maximum
Long Term Purchase Commitment [Line Items]
Lawsuits Filed Against Company | Lawsuit			7
Putative Class [Member]
Long Term Purchase Commitment [Line Items]
Number of settled and dismissed lawsuits | Lawsuit			8
Menlo Park Lease Agreement [Member]
Long Term Purchase Commitment [Line Items]
Letters of Credit issued amount	0.2		$ 0.2
Redwood City Lease Agreement [Member]
Long Term Purchase Commitment [Line Items]
Letters of Credit issued amount					$ 4.1
Boston, Massachusetts [Member]
Long Term Purchase Commitment [Line Items]
Letters of Credit issued amount	$ 0.2		$ 0.2

Commitments and Contingencies -

Commitments and Contingencies - Summary of Obligations Future Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020	$ 1,018
2021	4,124
2022	3,560
2023	3,428
2024	3,525
Years thereafter	17,371
Total	$ 33,026

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock (converted to Common Stock) - Summary of Redeemable Convertible Preferred Stock (Details) $ / shares in Units, $ in Thousands	Dec. 31, 2019USD ($)$ / sharesshares
Temporary Equity [Line Items]
Shares Authorized	99,363,444
Shares Issued and Outstanding	97,166,921
Carrying Value | $	$ 114,083
Liquidation Preference | $	$ 128,195
Common Stock Issued Upon Conversion (1)	12,048,671	[1]
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized	37,104,185
Original Issue Price | $ / shares	$ 1.20
Shares Issued and Outstanding	37,104,185
Carrying Value | $	$ 35,960
Liquidation Preference | $	$ 44,525
Common Stock Issued Upon Conversion (1)	4,600,920	[1]
Series A-1 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized	629,633
Original Issue Price | $ / shares	$ 1.20
Shares Issued and Outstanding	629,633
Carrying Value | $	$ 447
Liquidation Preference | $	$ 756
Common Stock Issued Upon Conversion (1)	78,074	[1]
Series A-2 Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized	2,428,688
Original Issue Price | $ / shares	$ 1.20
Shares Issued and Outstanding	2,428,688
Carrying Value | $	$ 1,749
Liquidation Preference | $	$ 2,914
Common Stock Issued Upon Conversion (1)	301,157	[1]
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized	59,200,938
Original Issue Price | $ / shares	$ 1.40
Shares Issued and Outstanding	57,004,415
Carrying Value | $	$ 75,927
Liquidation Preference | $	$ 80,000
Common Stock Issued Upon Conversion (1)	7,068,520	[1]
[1]	Adjusted to reflect the Exchange Ratio.

Redeemable Convertible Prefer_6

Redeemable Convertible Preferred Stock (converted to Common Stock) - Additional Information (Details) - shares		Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Number of common stock shares issued upon conversion	[1]				12,048,671
Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Number of common stock shares issued upon conversion		12,048,671
Number of shares outstanding		0	97,166,921	97,166,921	97,166,921	97,166,921	40,162,506	40,162,506	40,094,850
[1]	Adjusted to reflect the Exchange Ratio.

Redeemable Convertible Prefer_7

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 15, 2020	Dec. 31, 2019
Class Of Warrant Or Right [Line Items]
Number of warrants, Outstanding and exercisable to purchase preferred shares						1,781,387
Warrants outstanding and exercisable, Weighted average exercise price	$ 11.3177		$ 11.3177			$ 1.4034
Fair value of warrants outstanding					$ 2,900
Change in fair value of redeemable convertible preferred stock warrant liability			$ 897	$ (62)
Series B Warrants
Class Of Warrant Or Right [Line Items]
Fair value of warrants outstanding						$ 1,900
Series B Warrants | Maximum
Class Of Warrant Or Right [Line Items]
Change in fair value of redeemable convertible preferred stock warrant liability	$ 900	$ 100	$ 800	$ 100
Redeemable Convertible Preferred Stock | Series B Warrants
Class Of Warrant Or Right [Line Items]
Number of warrants, Outstanding and exercisable to purchase preferred shares	1,781,387		1,781,387
Warrants outstanding and exercisable, Weighted average exercise price	$ 1.4034		$ 1.4034

Redeemable Convertible Prefer_8

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants - Schedule of Redeemable Convertible Preferred Stock Warrant Liability Using Black-Scholes Option Pricing Model (Details)	Sep. 14, 2020$ / shares	Apr. 28, 2020$ / shares	Dec. 31, 2019$ / shares
Share Price
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement price	$ 16.59	$ 11.61	$ 11.32
Expected term (years)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement term		7 years
Expected term (years) | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement term	5 years 10 months 9 days		6 years 6 months 25 days
Expected term (years) | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement term	6 years 7 months 13 days		6 years 8 months 26 days
Expected volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input		91.17
Expected volatility | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	81.1		82.1
Expected volatility | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	82.1		93.3
Risk-free interest rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input		0.52
Risk-free interest rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.35		1.80
Risk-free interest rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.42		1.81
Dividend yield
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0	0	0

Redeemable Convertible Prefer_9

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants - Schedule of Outstanding Warrants (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Liabilities And Stockholders Equity [Abstract]
Number of warrants, Outstanding and exercisable to purchase preferred shares as of December 31, 2019	1,781,387
Number of warrants, Issued	128,260
Number of warrants, Converted to warrants for the purchase of common stock and adjusted for the Exchange Ratio and Reverse Stock Split	(1,672,854)
Number of warrants, Outstanding and exercisable to purchase common stock as of September 30, 2020	236,793
Warrant exercise price	$ 11.3177	$ 1.4034
Warrants outstanding and exercisable, Weighted average remaining contractual term	5 years 11 months 8 days	6 years 7 months 20 days

Redeemable Convertible Prefe_10

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants - Schedule of Outstanding Warrants to Purchase Shares of Common Stock (Details) - $ / shares	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Class Of Warrant Or Right [Line Items]
Number of Shares of Common Stock Issuable	236,793
Warrant exercise price	$ 11.3177	$ 1.4034
September 15, 2020 Warrant One
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 15, 2020
Number of Shares of Common Stock Issuable	101,610
Warrant exercise price	$ 11.3177
Expiration Date	Jul. 25, 2026
September 15, 2020 Warrant Two
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 15, 2020
Number of Shares of Common Stock Issuable	30,924
Warrant exercise price	$ 11.3177
Expiration Date	Aug. 21, 2026
September 15, 2020 Warrant Three
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 15, 2020
Number of Shares of Common Stock Issuable	77,312
Warrant exercise price	$ 11.3177
Expiration Date	Sep. 19, 2026
September 15, 2020 Warrant Four
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 15, 2020
Number of Shares of Common Stock Issuable	11,044
Warrant exercise price	$ 11.3177
Expiration Date	Sep. 26, 2026
September 15, 2020 Warrant Five
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 15, 2020
Number of Shares of Common Stock Issuable	15,903
Warrant exercise price	$ 11.3177
Expiration Date	Apr. 28, 2027

Redeemable Convertible Prefe_11

Redeemable Convertible Preferred Stock Warrants and Common Stock Warrants - Schedule of Outstanding Warrants to Purchase Shares of Redeemable Convertible Preferred Stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2020
Class Of Warrant Or Right [Line Items]
Number of Shares of Common Stock Issuable		236,793
Warrant exercise price	$ 1.4034	$ 11.3177
Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of Shares of Common Stock Issuable	1,781,387
Series B Warrants | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Warrant exercise price		$ 1.4034
Series B Warrants | July 25, 2019 Warrant | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Issuance Date	Jul. 25, 2019
Number of Shares of Common Stock Issuable	819,438
Warrant exercise price	$ 1.4034
Expiration Date	Jul. 25, 2026
Series B Warrants | August 21, 2019 Warrant | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Issuance Date	Aug. 21, 2019
Number of Shares of Common Stock Issuable	249,394
Warrant exercise price	$ 1.4034
Expiration Date	Aug. 21, 2026
Series B Warrants | September 19, 2019 Warrant | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 19, 2019
Number of Shares of Common Stock Issuable	623,486
Warrant exercise price	$ 1.4034
Expiration Date	Sep. 19, 2026
Series B Warrants | September 26, 2019 Warrant | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Issuance Date	Sep. 26, 2019
Number of Shares of Common Stock Issuable	89,069
Warrant exercise price	$ 1.4034
Expiration Date	Sep. 26, 2026

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	5,593,764	14,834,849
Stock Options Available for Future Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	2,098,174	653,136
Options Issued and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	3,269,399	1,860,646
Redeemable Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		12,048,671
Conversion of Additional Authorized and Unissued Redeemable Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		51,506
Redeemable Convertible Preferred Stock Warrant Liability
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		220,890
Common Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	226,191

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options exercised, Weighted-Average Exercise Price | $ / shares	$ 16.11
Options Issued and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, beginning, Number of Shares Available for Grant	653,136
Assumed as part of merger, Number of Shares Available for Grant	2,707,144
Options granted, Number of Shares Available for Grant	(1,517,446)
Options forfeited or cancelled, Number of Shares Available for Grant	255,340
Outstanding, ending, Number of Shares Available for Grant	2,098,174	653,136
Outstanding, beginning, Number of Shares Underlying Outstanding Options	1,860,646
Assumed as part of the Merger, Number of Shares Underlying Oustanding Options	81,370
Options granted, Number of Shares Underlying Outstanding Options	1,713,344
Options exercised, Number of Shares Underlying Outstanding Options	(123,141)
Options forfeited or cancelled, Number of Shares Underlying Outstanding Options	(262,820)
Outstanding, ending, Number of Shares Underlying Outstanding Options	3,269,399	1,860,646
Shares exercisable, Number of Shares Underlying Outstanding Options	1,195,101
Vested and expected to vest, Number of Shares Underlying Outstanding Options	3,269,399
Outstanding, beginning, Weighted-Average Exercise Price | $ / shares	$ 4.05
Assumed as part of the Merger, Weighted-Average Exercise Price | $ / shares	8.39
Options granted, Weighted-Average Exercise Price | $ / shares	16.06
Options exercised, Weighted-Average Exercise Price | $ / shares	1.57
Options forfeited or cancelled, Weighted-Average Exercise Price | $ / shares	4.80
Outstanding, ending, Weighted-Average Exercise Price | $ / shares	10.49	$ 4.05
Shares exercisable, Weighted-Average Exercise Price | $ / shares	4.20
Vested and expected to vest, Weighted-Average Exercise Price | $ / shares	$ 10.49
Outstanding, Weighted-Average Remaining Contract Term	7 years 8 months 23 days	8 years 6 months 10 days
Shares exercisable, Outstanding, Weighted-Average Remaining Contract Term	4 years 11 months 12 days
Vested and expected to vest, Weighted-Average Remaining Contract Term	7 years 8 months 23 days
Outstanding, beginning, Aggregate Intrinsic Value | $	$ 11,780	$ 5,812
Shares exercisable, Aggregate Intrinsic Value | $	9,246
Vested and expected to vest, Aggregate Intrinsic Value | $	$ 11,780

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,966	$ 391	$ 3,616	$ 865
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	951	54	1,125	191
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,015	$ 337	$ 2,491	$ 674

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 17, 2020	Jan. 01, 2020	Jan. 01, 2019	May 07, 2021	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for issuance					195,898			195,898
Options exercised, Weighted-Average Exercise Price								$ 16.11
Total stock-based compensation expense					$ 2,966		$ 391	$ 3,616	$ 865
Merger
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense					100
Option granted	16,931
Options granted, Weighted-Average Exercise Price	$ 16.11
Merger | Share-based Payment Arrangement, Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting rights								one-third of the shares vesting on the first anniversary
Merger | Share-based Payment Arrangement, Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting rights								one-third of the shares vesting in 12 equal monthly installments following such first anniversary
Merger | Share-based Payment Arrangement, Tranche Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting rights								one-third of the shares vesting in accordance with the terms of his Transition Agreement.
CEO Stock Option Modification
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense					$ 600
CEO Stock Option Modification | Scenario Forecast
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense				$ 100
2018 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of additional shares added on outstanding shares								4.00%
2017 and 2018 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock available for grant					1,462,006			1,462,006
Number of shares reserved for issuance					1,326,508			1,326,508
Options exercised, Weighted-Average Exercise Price								$ 15.64
2014 Stock Incentive Plan Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for issuance					69,014			69,014
Options exercised, Weighted-Average Exercise Price								$ 1.27
2015 Stock Incentive Plan Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for issuance					1,677,979			1,677,979
Options exercised, Weighted-Average Exercise Price								$ 6.14
2017 and 2018 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock available for grant					636,168			636,168
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of additional shares added on outstanding shares										1.00%
Number of shares reserved for issuance										39,290
Number of additional shares reserved for issuance		131,432	79,369
Number Of Shares Available For Sale Under Employee Stock Purchase Plan						0
2018 Employee Stock Purchase Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares reserved for issuance								77,703

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (14,779)	$ (14,778)	$ (27,720)	$ (21,560)
Weighted-average common shares used in computing net loss per share attributable to common stockholders, basic and diluted	5,208,887	2,149,986	3,190,557	2,133,645
Net loss per share attributable to common stockholders, basic and diluted	$ (2.84)	$ (6.87)	$ (8.69)	$ (10.10)

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, 2020	Sep. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,495,590	13,589,161
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	3,269,399	1,319,600
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	226,191
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		12,048,671
Redeemable Convertible Preferred Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		220,890

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)	$ 3	$ (2,676)	$ 1
COVID-19
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)		$ (2,700)
Operating loss carryback duration under CARES Act		5 years
Percentage of net operating loss carryforwards		80.00%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Preferred stock shares issued	0		0		0
Revenue—related party	$ 3,028	$ (7,047)	$ 12,493	$ (974)
Regeneron Pharmaceuticals, Inc.
Related Party Transaction [Line Items]
Revenue—related party	3,000	$ (7,000)	12,500	$ (1,000)
Accounts receivable	0		0
Deferred revenue	$ 19,400		$ 19,400
Regeneron Pharmaceuticals, Inc. | Series B Convertible Preferred Stock [ Member ]
Related Party Transaction [Line Items]
Preferred stock shares issued	883,568		883,568		883,568

Subsequent Events - Additional

Subsequent Events - Additional Information (Details)	Oct. 22, 2020
Subsequent Event
Subsequent Event [Line Items]
Subsequent event, description	On October 22, 2020, the U.S. Food and Drug Administration cleared the Company’s Investigational New Drug (“IND”) application for ADI-001, an allogeneic gamma delta T cell therapy expressing a chimeric antigen receptor (“CAR”) targeting CD20 for treatment of non-Hodgkin’s lymphoma (“NHL”). The active IND enables the Company to initiate the first-in-human clinical trial to assess safety and efficacy of ADI-001 in NHL patients.