Jounce Therapeutics (JNCE) 10-Q 9 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Aug. 04, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	JOUNCE THERAPEUTICS, INC.
Entity Central Index Key	1,640,455
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Trading Symbol	JNCE
Entity Common Stock, Shares Outstanding		32,194,213

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 43,482	$ 44,848
Short-term investments	227,321	104,410
Prepaid expenses and other current assets	8,513	2,529
Total current assets	279,316	151,787
Property and equipment, net	15,507	7,241
Long-term investments	39,086	108,116
Other non-current assets	2,535	4,168
Total assets	336,444	271,312
Current liabilities:
Accounts payable	3,104	3,511
Accrued expenses	6,411	5,855
Deferred rent and lease incentive, current	61	720
Deferred revenue, current—related party	69,235	80,544
Other current liabilities	49	43
Total current liabilities	78,860	90,673
Deferred rent and lease incentive, net of current portion	1,854	1,452
Deferred revenue, net of current portion—related party	77,990	107,260
Other non-current liabilities	41	56
Total liabilities	158,745	199,441
Commitments and contingencies
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value: 5,000 shares and no shares authorized at June 30, 2017 and December 31, 2016, respectively; no shares issued or outstanding at June 30, 2017 or December 31, 2016	0	0
Common stock, $0.001 par value: 160,000 shares and 29,810 shares authorized at June 30, 2017 and December 31, 2016, respectively; 32,181 and 2,518 shares issued at June 30, 2017 and December 31, 2016, respectively; 32,155 and 2,424 shares outstanding at June 30, 2017 and December 31, 2016, respectively	32	2
Additional paid-in capital	252,195	4,515
Accumulated other comprehensive loss	(552)	(433)
Accumulated deficit	(76,167)	(73,172)
Total stockholders’ equity (deficit)	175,508	(69,088)
Total liabilities, convertible preferred stock, contingently redeemable common stock and stockholders’ equity (deficit)	336,444	271,312
Convertible preferred stock (Series A)
Current liabilities:
Convertible preferred stock and contingently redeemable common stock	0	47,112
Convertible preferred stock (Series B)
Current liabilities:
Convertible preferred stock and contingently redeemable common stock	0	55,849
Convertible preferred stock (Series B-1)
Current liabilities:
Convertible preferred stock and contingently redeemable common stock	0	36,077
Contingently redeemable common stock
Current liabilities:
Convertible preferred stock and contingently redeemable common stock	$ 2,191	$ 1,921

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0
Preferred stock, shares authorized (in shares)	5,000,000	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	160,000,000	29,810,000
Common stock, shares issued (in shares)	32,181,000	2,518,000
Common stock, shares outstanding (in shares)	32,155,000	2,424,000
Convertible preferred stock (Series A)
Temporary equity, par value (in dollars per share)	$ 0.001	$ 0.001
Temporary equity, shares authorized (in shares)	0	47,000,000
Temporary equity, shares issued (in shares)	0	47,000,000
Temporary equity, shares outstanding (in shares)	0	47,000,000
Convertible preferred stock (Series B)
Temporary equity, par value (in dollars per share)	$ 0.001	$ 0.001
Temporary equity, shares authorized (in shares)	0	24,779,000
Temporary equity, shares issued (in shares)	0	24,779,000
Temporary equity, shares outstanding (in shares)	0	24,779,000
Convertible preferred stock (Series B-1)
Temporary equity, par value (in dollars per share)	$ 0.001	$ 0.001
Temporary equity, shares authorized (in shares)	0	10,448,000
Temporary equity, shares issued (in shares)	0	10,448,000
Temporary equity, shares outstanding (in shares)	0	10,448,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Collaboration revenue—related party	$ 20,289	$ 0	$ 40,578	$ 0
Operating expenses:
Research and development	17,188	6,490	32,147	14,745
General and administrative	6,129	5,872	11,706	8,518
Total operating expenses	23,317	12,362	43,853	23,263
Operating loss	(3,028)	(12,362)	(3,275)	(23,263)
Other income, net:
Other income, net	752	13	1,384	24
Total other income, net	752	13	1,384	24
Loss before provision for income taxes	(2,276)	(12,349)	(1,891)	(23,239)
Provision for income taxes	1,104	0	1,104	0
Net loss	(3,380)	(12,349)	(2,995)	(23,239)
Reconciliation of net loss to net loss attributable to common stockholders:
Net loss	(3,380)	(12,349)	(2,995)	(23,239)
Net loss attributable to common stockholders	$ (3,380)	$ (14,393)	$ (3,789)	$ (27,327)
Earnings Per Share, Basic and Diluted [Abstract]
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.11)	$ (7.23)	$ (0.14)	$ (14.05)
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Weighted-average common shares outstanding, basic and diluted (in shares)	32,144	1,991	27,867	1,945
Convertible preferred stock (Series A)
Reconciliation of net loss to net loss attributable to common stockholders:
Accrued dividends on convertible preferred stock	$ 0	$ (935)	$ (268)	$ (1,870)
Convertible preferred stock (Series B)
Reconciliation of net loss to net loss attributable to common stockholders:
Accrued dividends on convertible preferred stock	0	(1,109)	(318)	(2,218)
Convertible preferred stock (Series B-1)
Reconciliation of net loss to net loss attributable to common stockholders:
Accrued dividends on convertible preferred stock	$ 0	$ 0	$ (208)	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (3,380)	$ (12,349)	$ (2,995)	$ (23,239)
Other comprehensive loss:
Unrealized loss on available-for-sale securities	(66)	0	(119)	0
Comprehensive loss	$ (3,446)	$ (12,349)	$ (3,114)	$ (23,239)

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flow from operating activities:
Net loss	$ (2,995)	$ (23,239)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,389	1,095
Depreciation expense	2,591	912
Net amortization of premiums and discounts on investments	557	0
Changes in operating assets and liabilities:
Prepaid taxes	(4,896)	0
Prepaid expenses and other current assets	(837)	(1,271)
Other non-current assets	(87)	1,102
Accounts payable	323	(700)
Accrued expenses and other current liabilities	1,786	(845)
Deferred revenue—related party	(40,579)	0
Deferred rent	(257)	(330)
Net cash used in operating activities	(42,005)	(23,276)
Cash flow from investing activities:
Purchases of investments	(133,263)	0
Sales and maturities of investments	78,706	0
Purchases of property and equipment	(11,962)	(634)
Net cash used in investing activities	(66,519)	(634)
Cash flow from financing activities:
Proceeds from initial public offering of common stock, net of issuance costs	107,008	0
Proceeds from exercise of stock options	150	42
Cash paid for issuance costs	0	(3)
Net cash provided by financing activities	107,158	39
Net decrease in cash and cash equivalents	(1,366)	(23,871)
Cash and cash equivalents, beginning of period	44,848	45,161
Cash and cash equivalents, end of period	43,482	21,290
Supplemental disclosure of non-cash activities:
Purchases of property and equipment in accounts payable and accrued expenses	767	174
Issuance costs in accounts payable and accrued expenses	$ 0	$ 27

Nature of Business

Nature of Business	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Jounce Therapeutics, Inc. (the “Company”) is a clinical stage immunotherapy company dedicated to transforming the treatment of cancer by developing therapies that enable the immune system to attack tumors and bring long-lasting benefits to patients. The Company is subject to a number of risks similar to those of other clinical stage immunotherapy companies, including dependence on key individuals; the need to develop commercially viable products; competition from other companies, many of which are larger and better capitalized; and the need to obtain adequate additional financing to fund the development of its products. The Company’s lead product candidate, JTX-2011, is a clinical stage monoclonal antibody that binds to and activates ICOS, a protein on the surface of certain T cells commonly found in many solid tumors. The Company submitted an Investigational New Drug Application for JTX-2011 to the Food and Drug Administration in July 2016 and began the Phase I portion of its JTX-2011 multi-arm Phase I/II clinical trial in patients with solid tumors in August 2016. In June 2017, the Company presented preliminary safety, pharmacodynamic and pharmacokinetic data from the Phase I portion of this clinical trial as well as the recommended dose for the Phase II monotherapy cohorts at the 2017 American Society of Clinical Oncology Annual Meeting. In April 2017, the Company began the monotherapy cohorts of the Phase II portion of this clinical trial, which evaluate JTX-2011 as a monotherapy in at least three tumor-specific cohorts, including head and neck squamous cell cancer (“HNSCC”), non-small cell lung cancer (“NSCLC”) and non-indication specific solid tumors. In July 2017, the Company began the combination cohorts of the Phase II portion of this clinical trial, which evaluate JTX-2011 in combination with nivolumab in at least six tumor types, including HNSCC, NSCLC, triple negative breast cancer, melanoma, gastric cancer and additional tumor types based on emerging science. The Company expects to provide preliminary efficacy data in the first half of 2018. On February 1, 2017, the Company closed its initial public offering (“IPO”) of 7,319,750 shares of the Company’s common stock at a public offering price of $16.00 per share, including 954,750 shares of common stock issued upon the full exercise by the underwriters of their option to purchase additional shares. The gross proceeds from the IPO were $117.1 million and net proceeds were $106.4 million , after deducting underwriting discounts and commissions and other offering expenses paid by the Company. Upon completion of the IPO, all outstanding preferred stock was automatically converted into an aggregate of 22.3 million shares of common stock. In connection with the IPO, the Board of Directors and the stockholders of the Company approved a one-for-3.69 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on January 13, 2017. All share and per share amounts in the condensed consolidated financial statements have been retroactively adjusted for all periods presented to give effect to the reverse stock split, including reclassifying an amount equal to the reduction in par value to additional paid-in capital. As of June 30, 2017 , the Company had cash, cash equivalents, and investments of $309.9 million . The Company expects that its existing cash, cash equivalents, and investments will enable it to fund its expected operating expenses and capital expenditure requirements for at least 24 months from August 9, 2017 , the filing date of this Quarterly Report on Form 10-Q. The Company expects to finance its future cash needs through a combination of equity or debt financings and collaboration arrangements, including cash inflows from its Master Research and Collaboration Agreement (the “Celgene Collaboration Agreement”) with Celgene Corporation (“Celgene”).

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements as of June 30, 2017 and December 31, 2016 , and for the three and six months ended June 30, 2017 and 2016 , have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and generally accepted accounting principles in the United States of America (“GAAP”) for condensed consolidated financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these condensed consolidated financial statements reflect all normal recurring adjustments which are necessary for a fair presentation of the Company’s financial position and results of its operations, as of and for the periods presented. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 filed with the SEC on March 10, 2017 (the “Annual Report on Form 10-K”). The information presented in the condensed consolidated financial statements and related notes as of June 30, 2017 , and for the three and six months ended June 30, 2017 and 2016 , is unaudited. The December 31, 2016 condensed consolidated balance sheet included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements. Interim results for the six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 , or any future period. The accompanying condensed consolidated financial statements include the accounts of Jounce Therapeutics, Inc. and its wholly owned subsidiary, Jounce Mass Securities, Inc., which was established in July 2016. All intercompany transactions and balances have been eliminated in consolidation. Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2016 , and the notes thereto, which are included in the Company’s Annual Report on Form 10-K. There have been no material changes in the Company’s significant accounting policies during the six months ended June 30, 2017 . Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates which include, but are not limited to, estimates related to accrued expenses, stock-based compensation expense, income taxes and the period of performance for units of accounting identified under the Celgene Collaboration Agreement. The Company bases its estimates on historical experience and other market specific or other relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) , which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. This guidance was originally effective for interim and annual periods beginning after December 15, 2016 and allowed for adoption using a full retrospective method, or a modified retrospective method. Early adoption was originally not permitted. Subsequent to the issuance of ASU 2014-09, the FASB also issued the following updates related to Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers : • In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, whereby the effective date for the new revenue standard was deferred by one year. As a result of ASU 2015-14, the new revenue standard is now effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is now permitted for annual periods beginning after December 15, 2016, including interim periods within that annual period. • In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), to clarify the implementation guidance on principal versus agent considerations. • In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, to clarify the principle for determining whether a good or service is “separately identifiable” from other promises in the contract and to clarify the categorization of licenses of intellectual property. • In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Technical Expedients, to clarify guidance on transition, determining collectibility, non-cash consideration and the presentation of sales and other similar taxes. • In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, that allows entities not to make qualitative disclosures about remaining performance obligations in certain cases, adds disclosure requirements for entities that elect certain optional exemptions and adds twelve additional technical corrections and improvements to the new revenue standard. The Company currently anticipates adoption of ASC 606 effective January 1, 2018 under the modified retrospective method. The Company is in the process of determining the impact of ASC 606 on its financial statements, and the Company expects its analysis to be substantially completed by the third quarter of 2017. The adoption of ASC 606 may impact the timing of revenue recognized related to the $225.0 million upfront payment received under the Celgene Collaboration Agreement. The adoption of ASC 606 is also expected to have an impact on the Company’s footnote disclosures and its internal controls over financial reporting. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short-term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective beginning January 1, 2019, and early adoption is permitted for public entities. The Company is currently evaluating the potential impact that ASU 2016-02 may have on the condensed consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The new standard identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock-based compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the condensed consolidated statements of cash flows. The Company adopted ASU 2016-09 effective January 1, 2017, and the Company has elected to apply the simplification guidance related to the accounting for forfeitures. Accordingly, the Company will recognize gross stock-based compensation expense with actual forfeitures recognized as they occur. This simplification guidance related to the accounting for forfeitures is applied using a modified retrospective transition method. As forfeitures previously estimated by the Company through the year ended December 31, 2016 were not material, there was not a material cumulative-effect adjustment to accumulated deficit upon adoption of this guidance. The adoption of ASU 2016-09 also requires all excess tax benefits and tax deficiencies related to share-based payments to be recorded in the condensed consolidated statements of operations. The adoption of ASU 2016-09 did not have a material impact on the Company’s condensed consolidated financial statements as the expected increase in net deferred tax assets is expected to be offset by a corresponding increase in the deferred tax asset valuation allowance. The adoption of ASU 2016-09 is expected to impact the Company’s future income tax footnote disclosures related to the presentation of these excess tax benefits and tax deficiencies. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which is intended to reduce diversity in practice in how entities present certain types of cash transactions in the statement of cash flows. This guidance also clarifies how the predominance principle should be applied when classifying cash receipts and cash payments that have attributes of more than one class of cash flows. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. An entity that elects early adoption must adopt all of the amendments in the same period. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , which will require entities to show the change in the total of cash, cash equivalents, restricted cash and restricted cash equivalents within the statement of cash flows. As a result, entities will no longer separately present transfers between unrestricted cash and restricted cash. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance. In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting . This guidance is intended to provide clarity and reduce diversity in practice as to when changes to the terms or conditions of share-based payments are accounted for as modifications. Under this new guidance, entities will apply modification accounting if the fair value, vesting conditions or classification of the award changes. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. The guidance per ASU 2017-09 is to be adopted prospectively to an award modified on or after the adoption date. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance.

Celgene Collaboration Agreement

Celgene Collaboration Agreement	6 Months Ended
	Jun. 30, 2017
Research and Development [Abstract]
Celgene Collaboration Agreement	Celgene Collaboration Agreement In July 2016, the Company entered into the Celgene Collaboration Agreement. The primary goal of the collaboration is to co-develop and co-commercialize innovative biologic immunotherapies that either activate or suppress the immune system by binding to targets identified by leveraging the Company’s Translational Science Platform. Under the Celgene Collaboration Agreement, the Company granted Celgene exclusive options to develop and commercialize the Company’s lead product candidate, JTX-2011, and up to four early-stage programs, consisting of targets to be selected from a pool of certain B cell, T regulatory cell and tumor-associated macrophage targets. Additionally, Celgene has an exclusive option to develop and commercialize the Company’s product candidate JTX-4014, which, upon exercise of such option, will be a shared program that may be used by both parties in and outside of the collaboration. Prior to Celgene exercising any of its options, the Company is responsible for all research and development activities under the Celgene Collaboration Agreement. The Company received a non-refundable upfront cash payment of $225.0 million upon the execution of the Celgene Collaboration Agreement. The Company also received $36.1 million from the sale of 10,448,100 shares of Series B-1 convertible preferred stock upon the execution of a Series B-1 Preferred Stock Purchase Agreement with Celgene, which shares converted into 2,831,463 shares of common stock upon the completion of the IPO. If Celgene elects to exercise any of the program options, Celgene will pay the Company an option-exercise fee of $10.0 million to $60.0 million that varies by program, with an aggregate of $182.5 million if Celgene exercises all six program options. The initial research term of the collaboration is four years, which can be extended, at Celgene’s option, annually for up to three additional years for additional consideration that ranges from $30.0 million to $45.0 million per year, for an aggregate of $120.0 million if the term is extended for an additional three years. Worldwide Development Cost and U.S. Operating Profit and Loss Sharing Upon the exercise of each program option, the parties will enter into a co-development and co-commercialization agreement (“Co-Co Agreements”) or, in the case of JTX-4014, a license agreement (“JTX-4014 License Agreement”) that governs the development and commercialization of the applicable program. Although the agreements will not be executed unless and until Celgene exercises an option, the parties have agreed to the terms of the Co-Co Agreements and the JTX-4014 License Agreement as part of the Celgene Collaboration Agreement. Under the Co-Co Agreements and the JTX-4014 License Agreement, the Company will share with Celgene the U.S. profits or losses and development costs on such collaboration program as follows: • The Company will retain 60 percent of the U.S. operating profits or losses arising from commercialization of JTX-2011, with 40 percent allocated to Celgene. • The Company will retain 25 percent of the U.S. operating profits or losses arising from commercialization of the first program (the “Lead Program”), other than JTX-2011 or JTX-4014, for which an IND application is filed under the collaboration, with 75 percent allocated to Celgene. Celgene has a one-time right to substitute and swap the economics and governance of this program with that of another program for which it exercises an option (other than JTX-2011 and JTX-4014). • The Company and Celgene will equally share U.S. operating profits or losses arising from commercialization of up to three additional programs (other than JTX-2011, JTX-4014 or the Lead Program) (the “Other Programs”). • The Company and Celgene will share all development costs, other than for JTX-4014, in accordance with the applicable Co-Co Agreements, of which Celgene’s portion of the costs range from 67 percent to 85 percent. If Celgene exercises its option for a program other than JTX-4014, the Company will enter into a Co-Co Agreement, pursuant to which Celgene will have the exclusive right to develop and commercialize the products arising out of such collaboration program outside of the United States, and the Company will be eligible to receive tiered royalties ranging from a high single digit to mid-teen percentage rate on net product sales outside of the United States. Under each Co-Co Agreement, the Company will also have the right to opt out of profit sharing and instead receive milestones and royalties. Furthermore, if Celgene exercises its option for JTX-4014, the Company will enter into the JTX-4014 License Agreement, pursuant to which Celgene and the Company will each have equal rights to develop and commercialize JTX-4014 in combination with other proprietary molecules in their or the Company’s respective pipelines or in combination with products arising out of collaboration programs. Subject to terms specified in the license agreement for JTX-4014, the party owning the proprietary molecule that is combined with JTX-4014, if such molecule does not arise from a collaboration program with Celgene, will be solely responsible for all development and commercialization costs related to such combination. If JTX-4014 is combined with a product arising from a collaboration program, then the parties will share costs and, if co-packaged or co-formulated, profits or losses in accordance with the Co-Co Agreements for such other product. Milestones and Royalties Under the Co-Co Agreements and the JTX-4014 License Agreement, Celgene is required to pay the Company for specified development, regulatory and commercial milestones, if achieved, up to approximately $2.3 billion , across all collaboration programs. The development milestones are payable on initiation of certain clinical trials and range from $32.5 million to $105.0 million , per program, with an aggregate total of $290.0 million . The regulatory approval milestones are payable upon regulatory approval in the United States and outside the United States and range from $7.5 million to $50.0 million per milestone, with an aggregate total of $700.0 million . The commercial milestones are payable upon achievement of specified aggregate product sales outside the United States for each program and range from $40.0 million to $200.0 million per milestone, with an aggregate total of $1.270 billion . The Company is also eligible to receive royalties on product sales outside the United States ranging from high single digit to mid-teen royalties. Exercise of Options Celgene may exercise its option for a program at any time until the expiration of an option term for that program. For each program, the option term ends 45 to 60 days following Celgene’s receipt of a data package that includes certain information relating to the program’s research and development activities. The data package for a program may be delivered to Celgene after the applicable development milestone for such program has been achieved. Depending on the program, the applicable development milestone is (1) IND acceptance, (2) availability of certain Phase 1a data, or (3) availability of certain Phase I/II data. If Celgene fails to exercise its option during the option term for a program, the Company will continue to retain all rights to such program. If Celgene exercises its option for a program other than JTX-4014, then the Company will enter into a Co-Co Agreement with Celgene for such program in substantially the form attached to the agreement as an exhibit. Under the co-development and co-commercialization agreement for JTX-2011 and one additional program for which Celgene opts in that is not JTX-4014, the Company will be responsible for leading development and commercialization activities in the United States and Celgene will be responsible for development and commercialization activities outside the United States. For all other additional programs for which Celgene opts in, other than JTX-4014, Celgene will lead development and commercialization activities worldwide. If Celgene exercises its option for JTX-4014, the Company and Celgene will enter into a license agreement, in substantially the form attached to the agreement as an exhibit, pursuant to which the Company and Celgene will both be able to equally access JTX-4014 for combinations within each other’s portfolios and with other molecules that are subject to the agreement, subject to joint governance. Once Celgene opts in with respect to a given program, Celgene and the Company must each use commercially reasonable efforts to develop and commercialize the corresponding product in the United States. Termination At any point during the Celgene Collaboration Agreement, including during the research, development and clinical trial process, or during the term of the applicable co-development and co-commercialization or license agreement, respectively, Celgene can terminate the applicable agreement with the Company in its entirety, or with respect to any program under the Celgene Collaboration Agreement, upon 120 days’ notice and can terminate the entire agreement with the Company in connection with a material breach of the agreement by the Company that remains uncured for 90 days. Exclusivity During the Celgene Collaboration Agreement’s research term (i.e., for four years plus up to three one -year extensions that Celgene may elect), the Company may not alone, or with a third party, research, develop, manufacture or commercialize a biologic that binds to a defined pool of B cell, T regulatory cell or tumor-associated macrophage targets that meet certain criteria, termed an exclusive target, and inhibit, activate or otherwise modulate the activity of such exclusive target. In addition, if Celgene exercises its option for a program within the Celgene Collaboration Agreement, other than JTX-4014, then until termination or expiration of the applicable Co-Co Agreement for such program, the Company may not directly or indirectly research, develop, manufacture or commercialize, outside of the Celgene Collaboration Agreement, any biologic with specified activity against that program’s collaboration target. Accounting Analysis The Celgene Collaboration Agreement includes six deliverables: (i) research and development services for the product candidate, JTX-2011 (“JTX-2011 Research Services”) (ii) research and development services for the product candidate, JTX-4014 (“JTX-4014 Research Services”) (iii) research and development services associated with the Lead Program and Other Programs (“Lead and Other Programs Research Services”), (iv) research and development services associated with target screening (“Target Screening Services”), (v) non-transferable, sub-licensable and non-exclusive licenses to use the Company’s intellectual property and collaboration intellectual property to conduct research activities, on a program by program basis (“Research Licenses”), and (vi) participation in the joint steering committee (“JSC”). The six program options are considered substantive as the Company is at risk with regard to whether Celgene will exercise the options as a result of the significant uncertainties related to drug discovery, research and development as all options are for targets that have significant development risk. Additionally, there is also significant uncertainty regarding Celgene’s exercise of the option for JTX-4014 because, although not a novel immunotherapy agent, it has significant development risk associated with the Company’s ability to advance its development in a commercially viable manner in a short time frame. The research term extensions are also considered substantive options based upon the risk that Celgene will exercise the research term extension. In addition, there are substantial option exercise payments payable by Celgene upon exercise of each option that are not priced at a significant and incremental discount. Accordingly, the substantive options are not considered deliverables at the inception of the arrangement and the associated option exercise payments are not included in allocable arrangement consideration. The Company has also determined that any obligations which are contingent upon the exercise of a substantive option are not considered deliverables at the outset of the arrangement. The Target Screening Services and participation in the JSC deliverables each have standalone value from the other undelivered elements and therefore are separate units of accounting. The Company determined that the research licenses for the JTX-2011 and JTX-4014 programs do not have value to Celgene on a standalone basis primarily as a result of the fact that the research licenses allow Celgene to evaluate the results of the research and development services performed by the Company and the right to perform its duties under the agreement, but do not provide Celgene with any commercialization rights. Therefore, the research licenses do not have value to Celgene without the performance of the JTX-2011 Research Services and JTX-4014 Research Services and therefore are not separable from the JTX-2011 Research Services and JTX-4014 Research Services. The JTX-2011 Research Services are separate and distinct from the JTX-4014 Research Services, and therefore, the research license and the JTX-2011 Research Services are a separate combined unit of accounting and the research license and the JTX-4014 Research Services are a separate combined unit of accounting. The Lead and Other Programs Research Services deliverable does not include separate and distinct services and Celgene can use the Lead and Other Programs Research Services for its intended purpose without receipt of the research licenses that could be delivered for the Lead Program and Other Programs. The Lead and Other Programs Research Services therefore have been combined with the licenses that could be delivered for the Lead Program and Other Programs, which have an insignificant value, as a separate combined unit of accounting. The allocable arrangement consideration consists of the upfront fee of $225.0 million . As described above, Celgene also purchased 10,448,100 shares of Series B-1 convertible preferred stock for gross proceeds of $36.1 million , which shares converted into 2,831,463 shares of common stock upon the completion of the IPO. The Company determined the shares of Series B-1 convertible preferred stock were sold at fair value. Therefore, the proceeds from the issuance of Series B-1 convertible preferred stock did not impact the arrangement consideration to be allocated to the units of accounting. The Company has allocated the allocable arrangement consideration based on the relative selling price of each unit of accounting. For all units of accounting, the Company determined the selling price using the best estimate of selling price (“BESP”). The Company determined the BESP based on internal estimates of the costs to perform the services, including expected internal and external costs for services and supplies, adjusted to reflect a reasonable profit margin. The total cost of the research and development services reflects the nature of the services to be performed and the Company’s best estimate of the length of time required to perform the services. The Company determined that the BESP of the participation in the JSC was insignificant and therefore no consideration was allocated to this unit of accounting. Similarly, given the limited use of the research licenses, which is only required in the event Celgene performs research activities under the Celgene Collaboration Agreement which is not expected to be significant, the Company determined the estimated selling price for the research licenses were also insignificant. Therefore, the total allocable arrangement consideration has been allocated to the JTX-2011 Research Services, the JTX-4014 Research Services, the Lead and Other Programs Research Services and the Target Screening Services. The Company is recognizing the consideration allocated to each unit of accounting on a straight-line basis, as there is no discernible pattern or objective measure of performance of the services, over the estimated performance period. The estimated performance period reflects the Company’s estimate of the period over which it will perform the separate and distinct research and development services to deliver a pre-defined data package to Celgene for each program subject to an option. The performance periods for each unit of accounting range from twelve months to four years. The Company evaluated the milestones in the Celgene Collaboration Agreement, the Co-Co agreements, and the JTX-4014 License Agreement to determine if they are substantive. In evaluating if a milestone is substantive, the Company assesses whether: (i) the consideration is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. All development and regulatory milestones in the Celgene Collaboration Agreement, the Co-Co agreements, and the JTX-4014 License Agreement are considered substantive on the basis of the contingent nature of the milestone, specifically reviewing factors such as the scientific, clinical, regulatory, and other risks that must be overcome to achieve the milestone as well as the level of effort and investment required. Accordingly, such amounts will be recognized in the period in which the associated milestone is achieved, assuming all other revenue recognition criteria are met. All commercial milestones will be accounted for in the same manner as royalties and recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. During the six months ended June 30, 2017 , under the Celgene Collaboration Agreement, the Company recognized $40.6 million of the $225.0 million upfront payment as revenue. As of June 30, 2017 , the Company has $147.2 million of deferred revenue, which is classified as either current or net of current portion in the accompanying condensed consolidated balance sheets based on the period over which the revenue is expected to be recognized.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value is determined based on observable and unobservable inputs. Observable inputs reflect readily obtainable data from independent sources, while unobservable inputs reflect certain market assumptions. As a basis for considering such assumptions, GAAP establishes a three-tier value hierarchy, which prioritizes the inputs used to develop the assumptions and for measuring fair value as follows: (Level 1) observable inputs such as quoted prices in active markets for identical assets; (Level 2) inputs other than the quoted prices in active markets that are observable either directly or indirectly; and (Level 3) unobservable inputs in which there is little or no market data, which requires the Company to develop its own assumptions. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. The Company measures the fair value of money market funds, U.S. Treasuries and government agency securities based on quoted prices in active markets for identical securities. Investments also include corporate debt securities which are valued either based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data. The carrying amounts reflected in the condensed consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values, due to their short-term nature. Assets measured at fair value on a recurring basis as of June 30, 2017 were as follows (in thousands): June 30, 2017 Quoted prices in active markets for identical assets (level 1) Significant other observable inputs (level 2) Significant unobservable inputs (level 3) Money market funds, included in cash equivalents $ 43,482 $ 43,482 $ — $ — Investments: Corporate debt securities 83,750 — 83,750 — U.S. Treasuries 125,385 125,385 — — Government agency securities 57,272 57,272 — — Totals $ 309,889 $ 226,139 $ 83,750 $ — Assets measured at fair value on a recurring basis as of December 31, 2016 were as follows (in thousands): December 31, 2016 Quoted prices in active markets for identical assets (level 1) Significant other observable inputs (level 2) Significant unobservable inputs (level 3) Money market funds, included in cash equivalents $ 44,848 $ 44,848 $ — $ — Investments: Corporate debt securities 92,408 — 92,408 — U.S. Treasuries 120,118 120,118 — — Totals $ 257,374 $ 164,966 $ 92,408 $ — There were no changes in valuation techniques or transfers between the fair value measurement levels during the three or six months ended June 30, 2017 or during the year ended December 31, 2016 . There were no liabilities measured at fair value on a recurring basis as of June 30, 2017 or December 31, 2016 .

Investments

Investments	6 Months Ended
	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Short-term investments consist of investments with maturities greater than ninety days and less than one year from the balance sheet date. Long-term investments consist of investments with maturities of greater than one year that are not expected to be used to fund current operations. The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value. Realized gains and losses, amortization and accretion of discounts and premiums are included in other income, net. Unrealized gains and losses on available-for-sale securities are included in other comprehensive income (loss) as a component of stockholders’ equity (deficit) until realized. Cash and cash equivalents, short-term investments and long-term investments as of June 30, 2017 were comprised as follows (in thousands): June 30, 2017 Amortized cost Unrealized gains Unrealized losses Fair value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 43,482 $ — $ — $ 43,482 Corporate debt securities 76,883 1 (73 ) 76,811 U.S. Treasuries 125,749 — (364 ) 125,385 Government agency securities 25,163 — (38 ) 25,125 Total cash equivalents and short-term investments 271,277 1 (475 ) 270,803 Long-term investments: Corporate debt securities 6,950 — (11 ) 6,939 Government agency securities 32,214 1 (68 ) 32,147 Total long-term investments 39,164 1 (79 ) 39,086 Total cash equivalents and investments $ 310,441 $ 2 $ (554 ) $ 309,889 Cash and cash equivalents, short-term investments and long-term investments as of December 31, 2016 were comprised as follows (in thousands): December 31, 2016 Amortized cost Unrealized gains Unrealized losses Fair value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 44,848 $ — $ — $ 44,848 Corporate debt securities 92,549 — (141 ) 92,408 U.S. Treasuries 12,020 — (18 ) 12,002 Total cash equivalents and short-term investments 149,417 — (159 ) 149,258 Long-term investments: U.S. Treasuries 108,390 — (274 ) 108,116 Total long-term investments 108,390 — (274 ) 108,116 Total cash equivalents and investments $ 257,807 $ — $ (433 ) $ 257,374 As of June 30, 2017 and December 31, 2016 , the aggregate fair value of securities that were in an unrealized loss position for less than twelve months was $248.8 million and $192.3 million , respectively. The Company did not hold any securities in an unrealized loss position for more than twelve months as of June 30, 2017 or December 31, 2016 . As of June 30, 2017 , the Company did not intend to sell, and would not be more likely than not required to sell, the securities in an unrealized loss position before recovery of their amortized cost bases. Furthermore, the Company determined that there was no material change in the credit risk of these securities. As a result, the Company determined it did not hold any securities with any other-than-temporary impairment as of June 30, 2017 . There were no realized gains or losses on available-for-sale securities during the three or six months ended June 30, 2016 . There were immaterial realized gains and losses on available-for-sale securities during the three and six months ended June 30, 2017 .

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses as of June 30, 2017 and December 31, 2016 were comprised as follows (in thousands): June 30, December 31, 2017 2016 Employee compensation and benefits $ 1,995 $ 2,651 External research and professional services 3,413 1,923 Lab consumables and other 1,003 1,281 Total accrued expenses $ 6,411 $ 5,855

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Common Stock The Company is authorized to issue 160.0 million shares of common stock. Holders of common stock are entitled to one vote per share. Holders of common stock are entitled to receive dividends, if and when declared by the Board of Directors. Preferred Stock Upon completion of the Company’s IPO, all outstanding preferred stock was automatically converted into an aggregate of 22.3 million shares of common stock. The Company is also authorized to issue 5.0 million shares of undesignated preferred stock in one or more series. As of June 30, 2017 , no shares of preferred stock were issued or outstanding. Shares Reserved for Future Issuance The Company has reserved for future issuance the following number of shares of common stock (in thousands): June 30, December 31, 2017 2016 Shares reserved for Series A convertible preferred stock outstanding — 12,737 Shares reserved for Series B convertible preferred stock outstanding — 6,715 Shares reserved for Series B-1 convertible preferred stock outstanding — 2,831 Shares reserved for vesting of restricted stock awards 26 94 Shares reserved for exercises of outstanding stock options 4,663 4,290 Shares reserved for future issuances under the 2017 Stock Incentive Plan 1,322 244 Total shares reserved for future issuance 6,011 26,911

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-based Compensation 2013 Stock Option and Grant Plan In February 2013, the Company adopted the 2013 Stock Option and Grant Plan (the “2013 Plan”), as amended and restated, under which it could grant incentive stock options (“ISOs”), non-qualified stock options and restricted stock awards to eligible employees, officers, directors, and consultants. The 2013 Plan was subsequently amended in January 2015, April 2015, July 2015, March 2016 and October 2016 to allow for the issuance of additional shares of common stock. 2017 Stock Option and Incentive Plan In January 2017, the Company’s Board of Directors adopted and the Company’s stockholders approved the 2017 Stock Option and Incentive Plan (the “2017 Plan”), which became effective immediately prior to the effectiveness of the Company’s IPO. Upon the adoption of the 2017 Plan, no further awards will be granted under the 2013 Plan. The 2017 Plan provides for the grant of ISOs, non-qualified stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company’s employees, officers, directors and consultants and advisors are eligible to receive awards under the 2017 Plan. The Company registered on a Registration Statement on Form S-8 1,753,758 shares of common stock under the 2017 Plan, which is comprised of (i) 1,510,000 shares of common stock reserved for issuance under the 2017 Plan, plus (ii) 243,758 shares of common stock originally reserved for issuance under the 2013 Plan that became available for issuance under the 2017 Plan upon the completion of the Company’s IPO. The 2017 Plan also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 Plan on January 1, 2018 and each January 1 thereafter. The number of shares added each year will be equal to the lesser of (i) 4% of the outstanding shares on the immediately preceding December 31 st or (ii) such amount as determined by the Compensation Committee of the Board of Directors. The terms of stock options and restricted stock awards, including vesting requirements, are determined by the Board of Directors, subject to the provisions of the 2017 Plan. Stock options and restricted stock awards granted by the Company to employees and directors generally vest ratably over four years. Awards granted to new employees vest ratably over four years with 25% vesting on the first anniversary of employment and the remaining 75% vesting ratably, on a quarterly or monthly basis, over the remaining three years. Awards granted to non-employees generally vest monthly over one year. No restricted stock awards were issued during the three or six months ended June 30, 2017 or 2016 . No stock options were issued to non-employees during the three or six months ended June 30, 2017 or 2016 . As of June 30, 2017 , there were 1.3 million shares available for future issuance under the 2017 Plan. 2017 Employee Stock Purchase Plan In January 2017, the Board of Directors adopted and the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “2017 ESPP”), which became effective upon the closing of the Company’s IPO. The Company reserved 302,000 shares of common stock for future issuance under the 2017 ESPP. No offering periods under the 2017 ESPP had been initiated as of June 30, 2017 . Founder Awards From December 2012 to February 2013, the Company issued 1.4 million shares of restricted stock to non-employee founders (the “Founders”). Of the total restricted stock awarded to the Founders, 1.0 million shares vested over one to four years, based on each Founder’s continued service relationship with the Company in varying capacity as advisors, as prescribed by the grantee’s individual restricted stock purchase agreements. The remaining 0.4 million shares vested upon the determination by the Board of Directors of a Founder’s achievement of certain performance objectives, as set forth in the agreements. These performance criteria were linked to certain milestones specific to the Company’s research and development goals, including but not limited to preclinical and clinical development milestones related to the Company’s product candidates. As of June 30, 2017 , all restricted stock awards issued to Founders were vested. Restricted stock awards granted to two Founders contain options that enable the Founders to sell their vested shares back to the Company at fair value upon both (i) the termination of the consulting agreement between the Founder and the Company for any reason and (ii) the determination by the Founder’s employer that the ownership of the restricted stock is in violation of the employer’s conflict of interest policy. The occurrence of these events was determined to be outside of the Founders’ and the Company’s control. As such, these restricted stock awards have been recorded on the condensed consolidated balance sheet as contingently redeemable common stock, residing in temporary equity, in accordance with the classification guidance of ASC 718, Compensation—Stock Compensation and ASC 480, Distinguishing Liabilities from Equity. Further, in accordance with the measurement guidance of ASC 480, these restricted stock awards are not remeasured until such time as the contingent events become probable. In June 2017, the restricted stock purchase agreements related to the two Founders were amended such that these options expired on July 26, 2017. Stock-based Compensation Expense Total stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and six months ended June 30, 2017 and 2016 was as follows (in thousands): Three Months Ended Six Months Ended 2017 2016 2017 2016 Research and development $ 611 $ 505 $ 1,550 $ 810 General and administrative 425 150 839 285 Total stock-based compensation expense $ 1,036 $ 655 $ 2,389 $ 1,095 Restricted Stock Activity Pursuant to restricted stock agreements originally issued under the terms of the 2013 Plan, the Company, at its discretion, has the option to repurchase unvested shares at the initial purchase price if the employees or non-employees terminate their service relationship with the Company. The shares are recorded in stockholders’ equity (deficit) as they vest. The following table summarizes changes in unvested restricted stock for the six months ended June 30, 2017 (in thousands, except per share amounts): Shares Weighted-average grant date fair value per share Unvested restricted stock as of December 31, 2016 94 $ 0.07 Issued — $ — Vested (67 ) $ 0.08 Repurchased (1 ) $ 0.37 Unvested restricted stock as of June 30, 2017 26 $ 0.02 As of June 30, 2017 , there was unrecognized stock-based compensation expense related to unvested restricted stock awards of less than $0.1 million , which the Company expects to recognize over a weighted-average period of approximately 1.7 years . The aggregate fair value of restricted stock awards that vested during the three months ended June 30, 2017 and 2016 , based upon the fair values of the stock underlying the restricted stock awards on the day of vesting, was $0.2 million and $0.4 million , respectively. The aggregate fair value of restricted stock awards that vested during the six months ended June 30, 2017 and 2016 was $1.1 million and $0.7 million , respectively. Stock Option Activity The fair value of stock options during the three and six months ended June 30, 2017 and 2016 was calculated on the date of grant using the following weighted-average assumptions: Three Months Ended Six Months Ended 2017 2016 2017 2016 Risk-free interest rate 2.0 % 1.5 % 2.1 % 1.5 % Expected dividend yield — % — % — % — % Expected term (in years) 6.1 6.1 6.1 6.1 Expected volatility 73.6 % 70.5 % 73.6 % 69.5 % Using the Black-Scholes option pricing model, the weighted-average grant date fair value of stock options granted during the three months ended June 30, 2017 and 2016 was $15.33 per share and $2.66 per share, respectively. The weighted-average grant date fair value of stock options granted during the six months ended June 30, 2017 and 2016 was $12.05 per share and $2.60 per share, respectively. The following table summarizes changes in stock option activity during six months ended June 30, 2017 (in thousands, except per share amounts): Options Weighted-average exercise price Weighted average remaining contractual term (in years) Aggregate intrinsic value Outstanding at December 31, 2016 4,290 $ 3.95 8.7 $ 29,269 Granted 537 $ 18.26 Exercised (60 ) $ 2.49 Cancelled or forfeited (104 ) $ 6.24 Outstanding at June 30, 2017 4,663 $ 5.56 8.2 $ 41,720 Vested and expected to vest at June 30, 2017 4,663 $ 5.56 8.2 $ 41,720 Exercisable at June 30, 2017 1,675 $ 1.97 7.6 $ 20,199 The aggregate intrinsic value of stock options exercised during the three months ended June 30, 2017 and 2016 was $0.2 million and $0.2 million , respectively. The aggregate intrinsic value of stock options exercised during the six months ended June 30, 2017 and 2016 was $1.0 million and $0.3 million , respectively. As of June 30, 2017 , there was unrecognized stock-based compensation expense related to unvested stock options of $13.3 million , which the Company expects to recognize over a weighted-average period of approximately 2.6 years .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Net operating loss (“NOL”) and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service (“IRS”) and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50% as defined under Sections 382 and 383 in the Internal Revenue Code (the “IRC”). This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the Company's value immediately prior to the ownership change. An IRC Section 382 study, completed in August 2016, identified three previous ownership changes for purposes of IRC Section 382. As a result of these ownership changes, the Company's NOL and tax credit carryforwards allocable to the periods preceding each such ownership change are subject to limitations under IRC Section 382. Subsequent ownership changes may further affect the limitation in future years. Pursuant to IRS Revenue Procedure 2004-34, the Company will recognize additional revenue for income tax purposes during the year ended December 31, 2017 related to the upfront cash payment that was received upon the execution of the Celgene Collaboration Agreement in July 2016. As the revenue to be recognized for income tax purposes is expected to exceed the Company’s eligible NOL and tax credit carryforwards generated since inception, as limited by IRC Section 382, the Company expects to incur approximately $16.0 million to $18.0 million in federal and state tax liabilities during the year ended December 31, 2017. The Company’s overall provision for income taxes of $1.1 million for the three and six months ended June 30, 2017 is less than the estimated federal and state tax liabilities due to the tax benefit the Company is able to recognize related to deferred tax assets that the Company has concluded it will more likely than not realize in future periods.

Related-Party Transactions

Related-Party Transactions	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Related-party Transactions	Related-party Transactions In July 2016, the Company entered into the Celgene Collaboration Agreement and a Series B-1 Preferred Stock Purchase Agreement with Celgene. Under the Celgene Collaboration Agreement, the Company received a non-refundable upfront payment of $225.0 million . Under the Series B-1 Preferred Stock Purchase Agreement, Celgene purchased 10,448,100 shares of Series B-1 preferred stock for $36.1 million . These shares of Series B-1 preferred stock converted into 2,831,463 shares of common stock upon the completion of the Company’s IPO. In addition, an affiliate of Celgene purchased 625,000 shares of the Company’s common stock in the IPO at the public offering price of $16.00 per share for a total of $10.0 million .

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share For purposes of the diluted net loss per share calculation, convertible preferred stock, outstanding stock options and unvested restricted common stock are considered to be potentially dilutive securities, but are excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented. The following potentially dilutive securities have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive effect (in common stock equivalent shares): Three and Six Months Ended 2017 2016 Series A convertible preferred stock — 12,737 Series B convertible preferred stock — 6,715 Outstanding stock options 4,663 3,178 Unvested restricted common stock 26 466 Total 4,689 23,096

Basis of Presentation and Sum18

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements as of June 30, 2017 and December 31, 2016 , and for the three and six months ended June 30, 2017 and 2016 , have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and generally accepted accounting principles in the United States of America (“GAAP”) for condensed consolidated financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these condensed consolidated financial statements reflect all normal recurring adjustments which are necessary for a fair presentation of the Company’s financial position and results of its operations, as of and for the periods presented. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 filed with the SEC on March 10, 2017 (the “Annual Report on Form 10-K”). The information presented in the condensed consolidated financial statements and related notes as of June 30, 2017 , and for the three and six months ended June 30, 2017 and 2016 , is unaudited. The December 31, 2016 condensed consolidated balance sheet included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements. Interim results for the six months ended June 30, 2017 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2017 , or any future period.
Principles of Consolidation	The accompanying condensed consolidated financial statements include the accounts of Jounce Therapeutics, Inc. and its wholly owned subsidiary, Jounce Mass Securities, Inc., which was established in July 2016. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates which include, but are not limited to, estimates related to accrued expenses, stock-based compensation expense, income taxes and the period of performance for units of accounting identified under the Celgene Collaboration Agreement. The Company bases its estimates on historical experience and other market specific or other relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) , which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. This guidance was originally effective for interim and annual periods beginning after December 15, 2016 and allowed for adoption using a full retrospective method, or a modified retrospective method. Early adoption was originally not permitted. Subsequent to the issuance of ASU 2014-09, the FASB also issued the following updates related to Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers : • In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, whereby the effective date for the new revenue standard was deferred by one year. As a result of ASU 2015-14, the new revenue standard is now effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, and early adoption is now permitted for annual periods beginning after December 15, 2016, including interim periods within that annual period. • In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), to clarify the implementation guidance on principal versus agent considerations. • In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, to clarify the principle for determining whether a good or service is “separately identifiable” from other promises in the contract and to clarify the categorization of licenses of intellectual property. • In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Technical Expedients, to clarify guidance on transition, determining collectibility, non-cash consideration and the presentation of sales and other similar taxes. • In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, that allows entities not to make qualitative disclosures about remaining performance obligations in certain cases, adds disclosure requirements for entities that elect certain optional exemptions and adds twelve additional technical corrections and improvements to the new revenue standard. The Company currently anticipates adoption of ASC 606 effective January 1, 2018 under the modified retrospective method. The Company is in the process of determining the impact of ASC 606 on its financial statements, and the Company expects its analysis to be substantially completed by the third quarter of 2017. The adoption of ASC 606 may impact the timing of revenue recognized related to the $225.0 million upfront payment received under the Celgene Collaboration Agreement. The adoption of ASC 606 is also expected to have an impact on the Company’s footnote disclosures and its internal controls over financial reporting. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short-term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective beginning January 1, 2019, and early adoption is permitted for public entities. The Company is currently evaluating the potential impact that ASU 2016-02 may have on the condensed consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The new standard identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock-based compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the condensed consolidated statements of cash flows. The Company adopted ASU 2016-09 effective January 1, 2017, and the Company has elected to apply the simplification guidance related to the accounting for forfeitures. Accordingly, the Company will recognize gross stock-based compensation expense with actual forfeitures recognized as they occur. This simplification guidance related to the accounting for forfeitures is applied using a modified retrospective transition method. As forfeitures previously estimated by the Company through the year ended December 31, 2016 were not material, there was not a material cumulative-effect adjustment to accumulated deficit upon adoption of this guidance. The adoption of ASU 2016-09 also requires all excess tax benefits and tax deficiencies related to share-based payments to be recorded in the condensed consolidated statements of operations. The adoption of ASU 2016-09 did not have a material impact on the Company’s condensed consolidated financial statements as the expected increase in net deferred tax assets is expected to be offset by a corresponding increase in the deferred tax asset valuation allowance. The adoption of ASU 2016-09 is expected to impact the Company’s future income tax footnote disclosures related to the presentation of these excess tax benefits and tax deficiencies. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which is intended to reduce diversity in practice in how entities present certain types of cash transactions in the statement of cash flows. This guidance also clarifies how the predominance principle should be applied when classifying cash receipts and cash payments that have attributes of more than one class of cash flows. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. An entity that elects early adoption must adopt all of the amendments in the same period. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , which will require entities to show the change in the total of cash, cash equivalents, restricted cash and restricted cash equivalents within the statement of cash flows. As a result, entities will no longer separately present transfers between unrestricted cash and restricted cash. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance. In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting . This guidance is intended to provide clarity and reduce diversity in practice as to when changes to the terms or conditions of share-based payments are accounted for as modifications. Under this new guidance, entities will apply modification accounting if the fair value, vesting conditions or classification of the award changes. This guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual reporting periods, and early adoption is permitted. The guidance per ASU 2017-09 is to be adopted prospectively to an award modified on or after the adoption date. The Company does not anticipate a material impact to the condensed consolidated financial statements as a result of the adoption of this guidance.
Fair Value Measurements	Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value is determined based on observable and unobservable inputs. Observable inputs reflect readily obtainable data from independent sources, while unobservable inputs reflect certain market assumptions. As a basis for considering such assumptions, GAAP establishes a three-tier value hierarchy, which prioritizes the inputs used to develop the assumptions and for measuring fair value as follows: (Level 1) observable inputs such as quoted prices in active markets for identical assets; (Level 2) inputs other than the quoted prices in active markets that are observable either directly or indirectly; and (Level 3) unobservable inputs in which there is little or no market data, which requires the Company to develop its own assumptions. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. The Company measures the fair value of money market funds, U.S. Treasuries and government agency securities based on quoted prices in active markets for identical securities. Investments also include corporate debt securities which are valued either based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data. The carrying amounts reflected in the condensed consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values, due to their short-term nature.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value	Assets measured at fair value on a recurring basis as of June 30, 2017 were as follows (in thousands): June 30, 2017 Quoted prices in active markets for identical assets (level 1) Significant other observable inputs (level 2) Significant unobservable inputs (level 3) Money market funds, included in cash equivalents $ 43,482 $ 43,482 $ — $ — Investments: Corporate debt securities 83,750 — 83,750 — U.S. Treasuries 125,385 125,385 — — Government agency securities 57,272 57,272 — — Totals $ 309,889 $ 226,139 $ 83,750 $ — Assets measured at fair value on a recurring basis as of December 31, 2016 were as follows (in thousands): December 31, 2016 Quoted prices in active markets for identical assets (level 1) Significant other observable inputs (level 2) Significant unobservable inputs (level 3) Money market funds, included in cash equivalents $ 44,848 $ 44,848 $ — $ — Investments: Corporate debt securities 92,408 — 92,408 — U.S. Treasuries 120,118 120,118 — — Totals $ 257,374 $ 164,966 $ 92,408 $ —

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities by Security Type	Cash and cash equivalents, short-term investments and long-term investments as of June 30, 2017 were comprised as follows (in thousands): June 30, 2017 Amortized cost Unrealized gains Unrealized losses Fair value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 43,482 $ — $ — $ 43,482 Corporate debt securities 76,883 1 (73 ) 76,811 U.S. Treasuries 125,749 — (364 ) 125,385 Government agency securities 25,163 — (38 ) 25,125 Total cash equivalents and short-term investments 271,277 1 (475 ) 270,803 Long-term investments: Corporate debt securities 6,950 — (11 ) 6,939 Government agency securities 32,214 1 (68 ) 32,147 Total long-term investments 39,164 1 (79 ) 39,086 Total cash equivalents and investments $ 310,441 $ 2 $ (554 ) $ 309,889 Cash and cash equivalents, short-term investments and long-term investments as of December 31, 2016 were comprised as follows (in thousands): December 31, 2016 Amortized cost Unrealized gains Unrealized losses Fair value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 44,848 $ — $ — $ 44,848 Corporate debt securities 92,549 — (141 ) 92,408 U.S. Treasuries 12,020 — (18 ) 12,002 Total cash equivalents and short-term investments 149,417 — (159 ) 149,258 Long-term investments: U.S. Treasuries 108,390 — (274 ) 108,116 Total long-term investments 108,390 — (274 ) 108,116 Total cash equivalents and investments $ 257,807 $ — $ (433 ) $ 257,374

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses as of June 30, 2017 and December 31, 2016 were comprised as follows (in thousands): June 30, December 31, 2017 2016 Employee compensation and benefits $ 1,995 $ 2,651 External research and professional services 3,413 1,923 Lab consumables and other 1,003 1,281 Total accrued expenses $ 6,411 $ 5,855

Common Stock and Preferred St22

Common Stock and Preferred Stock (Tables)	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Schedule of Stock by Class	The Company has reserved for future issuance the following number of shares of common stock (in thousands): June 30, December 31, 2017 2016 Shares reserved for Series A convertible preferred stock outstanding — 12,737 Shares reserved for Series B convertible preferred stock outstanding — 6,715 Shares reserved for Series B-1 convertible preferred stock outstanding — 2,831 Shares reserved for vesting of restricted stock awards 26 94 Shares reserved for exercises of outstanding stock options 4,663 4,290 Shares reserved for future issuances under the 2017 Stock Incentive Plan 1,322 244 Total shares reserved for future issuance 6,011 26,911

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The fair value of stock options during the three and six months ended June 30, 2017 and 2016 was calculated on the date of grant using the following weighted-average assumptions: Three Months Ended Six Months Ended 2017 2016 2017 2016 Risk-free interest rate 2.0 % 1.5 % 2.1 % 1.5 % Expected dividend yield — % — % — % — % Expected term (in years) 6.1 6.1 6.1 6.1 Expected volatility 73.6 % 70.5 % 73.6 % 69.5 %
Schedule of Stock-Based Compensation Expense	Total stock-based compensation expense recognized in the condensed consolidated statements of operations for the three and six months ended June 30, 2017 and 2016 was as follows (in thousands): Three Months Ended Six Months Ended 2017 2016 2017 2016 Research and development $ 611 $ 505 $ 1,550 $ 810 General and administrative 425 150 839 285 Total stock-based compensation expense $ 1,036 $ 655 $ 2,389 $ 1,095
Schedule of Restricted Stock Activity	The following table summarizes changes in unvested restricted stock for the six months ended June 30, 2017 (in thousands, except per share amounts): Shares Weighted-average grant date fair value per share Unvested restricted stock as of December 31, 2016 94 $ 0.07 Issued — $ — Vested (67 ) $ 0.08 Repurchased (1 ) $ 0.37 Unvested restricted stock as of June 30, 2017 26 $ 0.02
Schedule of Stock Options, Activity	The following table summarizes changes in stock option activity during six months ended June 30, 2017 (in thousands, except per share amounts): Options Weighted-average exercise price Weighted average remaining contractual term (in years) Aggregate intrinsic value Outstanding at December 31, 2016 4,290 $ 3.95 8.7 $ 29,269 Granted 537 $ 18.26 Exercised (60 ) $ 2.49 Cancelled or forfeited (104 ) $ 6.24 Outstanding at June 30, 2017 4,663 $ 5.56 8.2 $ 41,720 Vested and expected to vest at June 30, 2017 4,663 $ 5.56 8.2 $ 41,720 Exercisable at June 30, 2017 1,675 $ 1.97 7.6 $ 20,199

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share	The following potentially dilutive securities have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive effect (in common stock equivalent shares): Three and Six Months Ended 2017 2016 Series A convertible preferred stock — 12,737 Series B convertible preferred stock — 6,715 Outstanding stock options 4,663 3,178 Unvested restricted common stock 26 466 Total 4,689 23,096

Nature of Business (Details)

Nature of Business (Details) $ / shares in Units, $ in Thousands	Aug. 09, 2017	Feb. 01, 2017USD ($)$ / sharesshares	Jan. 13, 2017	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from initial public offering of common stock, net of issuance costs				$ 107,008	$ 0
Reverse stock split			0.2710
Cash, cash equivalents, and marketable securities				$ 309,900
IPO
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Issuance of common stock (in shares) | shares		7,319,750
Public offering share price (in dollars per share) | $ / shares		$ 16
Proceeds from initial public offering of common stock, net of issuance costs		$ 117,100
Proceeds from IPO, net of discounts, commissions, and other offering expenses		$ 106,400
Stock converted upon completion of IPO (in shares) | shares		22,300,000
Over-Allotment Option
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Issuance of common stock (in shares) | shares		954,750
Scenario, Forecast
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Duration of funding requirement	24 months

Basis of Presentation and Sum26

Basis of Presentation and Summary of Significant Accounting Policies Narrative (Details) - Celegene Collaborative Arrangement - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2016	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-refundable upfront payment received for research agreement	$ 225
Accounting Standards Update 2014-09 | Scenario, Forecast
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Non-refundable upfront payment received for research agreement		$ 225

Celgene Collaboration Agreeme27

Celgene Collaboration Agreement (Details) $ in Millions	Feb. 01, 2017shares	Jul. 31, 2016USD ($)extensiondeliverablecustomer_programshares	Jun. 30, 2017USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of program extensions | extension		3
Program extension research term		1 year
Collaboration revenue—related party			$ 40.6
Deferred revenue			$ 147.2
Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of early-stage programs | customer_program		4
Non-refundable upfront payment received for research agreement		$ 225
Aggregate option-exercise fees from program options		$ 182.5
Number of program options | deliverable		6
Initial research term		4 years
Potential addition to research term		3 years
Aggregate consideration for additional years of research		$ 120
Potential milestone revenue		2,300
Aggregate development milestone revenue		290
Aggregate regulatory approval milestone revenue		700
Aggregate commercial milestone revenue		1,270
Convertible preferred stock (Series B-1) | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuances of convertible preferred stock		$ 36.1
Issuances of convertible preferred stock (in shares) | shares		10,448,100
Minimum | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Option-exercise fee for program option		$ 10
Consideration for additional year of research		30
Development milestone revenue, per program		32.5
Regulatory approval milestone revenue, per program		7.5
Commercial milestone revenue, per program		$ 40
Program option term		45 days
Performance period for unit of accounting		12 months
Maximum | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Option-exercise fee for program option		$ 60
Consideration for additional year of research		45
Development milestone revenue, per program		105
Regulatory approval milestone revenue, per program		50
Commercial milestone revenue, per program		$ 200
Program option term		60 days
Performance period for unit of accounting		4 years
JTX-2011 | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		60.00%
JTX-2011 | Celgene Corporation | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		40.00%
Lead Program | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		25.00%
Lead Program | Celgene Corporation | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		75.00%
Other Programs | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		50.00%
Other Programs | Celgene Corporation | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of operating profit or loss retained		50.00%
All Programs, Excluding JTX-4014 | Celgene Corporation | Minimum | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of development costs		67.00%
All Programs, Excluding JTX-4014 | Celgene Corporation | Maximum | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percent of development costs		85.00%
IPO
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock converted upon completion of IPO (in shares) | shares	22,300,000
Celgene Corporation | Celgene Collaboration Agreement | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront payment received for research agreement		$ 225
Celgene Corporation | Celgene Collaboration Agreement | Convertible preferred stock (Series B-1) | Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuances of convertible preferred stock		$ 36.1
Issuances of convertible preferred stock (in shares) | shares		10,448,100
Celgene Corporation | Celgene Collaboration Agreement | IPO | Common Stock
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock converted upon completion of IPO (in shares) | shares	2,831,463

Fair Value Measurements Assets

Fair Value Measurements Assets Measured at Fair Value (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Measurements, Recurring
Investments:
Totals	$ 309,889,000	$ 257,374,000
Liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (level 1)
Investments:
Totals	226,139,000	164,966,000
Fair Value, Measurements, Recurring | Significant other observable inputs (level 2)
Investments:
Totals	83,750,000	92,408,000
Fair Value, Measurements, Recurring | Significant unobservable inputs (level 3)
Investments:
Totals	0	0
Money market funds, included in cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, included in cash equivalents	43,482,000	44,848,000
Money market funds, included in cash equivalents | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, included in cash equivalents	43,482,000	44,848,000
Money market funds, included in cash equivalents | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, included in cash equivalents	43,482,000	44,848,000
Money market funds, included in cash equivalents | Fair Value, Measurements, Recurring | Significant other observable inputs (level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, included in cash equivalents	0	0
Money market funds, included in cash equivalents | Fair Value, Measurements, Recurring | Significant unobservable inputs (level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, included in cash equivalents	0	0
Corporate debt securities | Fair Value, Measurements, Recurring
Investments:
Available-for-sale debt securities, fair value	83,750,000	92,408,000
Corporate debt securities | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (level 1)
Investments:
Available-for-sale debt securities, fair value	0	0
Corporate debt securities | Fair Value, Measurements, Recurring | Significant other observable inputs (level 2)
Investments:
Available-for-sale debt securities, fair value	83,750,000	92,408,000
Corporate debt securities | Fair Value, Measurements, Recurring | Significant unobservable inputs (level 3)
Investments:
Available-for-sale debt securities, fair value	0	0
U.S. Treasuries | Fair Value, Measurements, Recurring
Investments:
Available-for-sale debt securities, fair value	125,385,000	120,118,000
U.S. Treasuries | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (level 1)
Investments:
Available-for-sale debt securities, fair value	125,385,000	120,118,000
U.S. Treasuries | Fair Value, Measurements, Recurring | Significant other observable inputs (level 2)
Investments:
Available-for-sale debt securities, fair value	0	0
U.S. Treasuries | Fair Value, Measurements, Recurring | Significant unobservable inputs (level 3)
Investments:
Available-for-sale debt securities, fair value	0	$ 0
Government agency securities | Fair Value, Measurements, Recurring
Investments:
Available-for-sale debt securities, fair value	57,272,000
Government agency securities | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (level 1)
Investments:
Available-for-sale debt securities, fair value	57,272,000
Government agency securities | Fair Value, Measurements, Recurring | Significant other observable inputs (level 2)
Investments:
Available-for-sale debt securities, fair value	0
Government agency securities | Fair Value, Measurements, Recurring | Significant unobservable inputs (level 3)
Investments:
Available-for-sale debt securities, fair value	$ 0

Investments Available-for-sale

Investments Available-for-sale Securities by Security Type (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Unrealized gains	$ 2	$ 0
Unrealized losses	(554)	(433)
Cash equivalents, short-term and long-term investments, carrying value	310,441	257,807
Cash equivalents, short-term and long-term investments, fair vale disclosure	309,889	257,374
Money market funds, included in cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents at carrying value	43,482	44,848
Cash equivalents at fair value	43,482	44,848
Short-term Investments
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Unrealized gains	1	0
Unrealized losses	(475)	(159)
Total cash equivalents and short-term investments, carrying value	271,277	149,417
Total cash equivalents and short-term investments, fair value	270,803	149,258
Short-term Investments | Corporate debt securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	76,883	92,549
Unrealized gains	1	0
Unrealized losses	(73)	(141)
Available-for-sale debt securities, fair value	76,811	92,408
Short-term Investments | U.S. Treasuries
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	125,749	12,020
Unrealized gains	0	0
Unrealized losses	(364)	(18)
Available-for-sale debt securities, fair value	125,385	12,002
Short-term Investments | Government agency securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	25,163
Unrealized gains	0
Unrealized losses	(38)
Available-for-sale debt securities, fair value	25,125
Long-term Investments
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	39,164	108,390
Unrealized gains	1	0
Unrealized losses	(79)	(274)
Available-for-sale debt securities, fair value	39,086	108,116
Long-term Investments | Corporate debt securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	6,950
Unrealized gains	0
Unrealized losses	(11)
Available-for-sale debt securities, fair value	6,939
Long-term Investments | U.S. Treasuries
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis		108,390
Unrealized gains		0
Unrealized losses		(274)
Available-for-sale debt securities, fair value		$ 108,116
Long-term Investments | Government agency securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Available-for-sale debt securities, amortized cost basis	32,214
Unrealized gains	1
Unrealized losses	(68)
Available-for-sale debt securities, fair value	$ 32,147

Investments Narrative (Details)

Investments Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)investment	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)investment	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)investment
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities in an unrealized loss position for less than twelve months	$ 248,800,000		$ 248,800,000		$ 192,300,000
Number of securities in unrealized loss position, greater than 12 months | investment	0		0		0
Realized gains or losses on available-for-sale securities	$ 0	$ 0	$ 0	$ 0

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 1,995	$ 2,651
External research and professional services	3,413	1,923
Lab consumables and other	1,003	1,281
Total accrued expenses	$ 6,411	$ 5,855

Common Stock and Preferred St32

Common Stock and Preferred Stock - Narrative (Details)	Feb. 01, 2017shares	Jun. 30, 2017voteshares	Dec. 31, 2016shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		160,000,000	29,810,000
Common Stock, Votes Per Share | vote		1
Preferred stock, shares authorized (in shares)		5,000,000	0
Preferred stock, shares issued (in shares)		0	0
Preferred stock, shares outstanding (in shares)		0	0
IPO
Class of Stock [Line Items]
Stock converted upon completion of IPO (in shares)	22,300,000

Common Stock and Preferred St33

Common Stock and Preferred Stock - Shares Reserved for Future Issuance (Details) - shares	Jun. 30, 2017	Jan. 31, 2017	Dec. 31, 2016
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	6,011,000	1,753,758	26,911,000
Convertible preferred stock (Series A)
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	0		12,737,000
Convertible preferred stock (Series B)
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	0		6,715,000
Convertible preferred stock (Series B-1)
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	0		2,831,000
Restricted Stock
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	26,000		94,000
Outstanding Employee Stock Options
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	4,663,000		4,290,000
Future Issuances from Employee Stock Options
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)			244,000
Shares of common stock reserved for issuance (in shares)	1,322,000

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details)	3 Months Ended			6 Months Ended
	Jun. 30, 2017USD ($)non-employee$ / sharesshares	Jun. 30, 2016USD ($)$ / sharesshares	Feb. 28, 2013shares	Jun. 30, 2017USD ($)non-employee$ / sharesshares	Jun. 30, 2016USD ($)$ / sharesshares	Jan. 31, 2017shares	Dec. 31, 2016shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)	6,011,000			6,011,000		1,753,758	26,911,000
Stock options issued (in shares)				537,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)	26,000			26,000			94,000
Issued (in shares)				0
Unrecognized stock-based compensation expense (less than) | $	$ 100,000			$ 100,000
Remaining weighted average vesting period				1 year 8 months 12 days
Aggregate fair value of awards vested in period | $	$ 200,000	$ 400,000		$ 1,100,000	$ 700,000
Future Issuances from Employee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)	1,322,000			1,322,000
Shares of common stock eligible to be purchased (in shares)							244,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining weighted average vesting period				2 years 7 months 21 days
Weighted average fair value of options granted (in dollars per share) | $ / shares	$ 15.33	$ 2.66		$ 12.05	$ 2.60
Unrecognized stock-based compensation expense, options | $	$ 13,300,000			$ 13,300,000
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)						1,510,000
Percent of outstanding shares able to be added each year						4.00%
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)						0
Shares of common stock eligible to be purchased (in shares)						243,758
2013 Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued (in shares)	0	0		0	0
2013 Stock Option and Grant Plan, Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
2013 Stock Option and Grant Plan, Employees | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent vested				25.00%
2013 Stock Option and Grant Plan, Employees | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				3 years
Percent vested				75.00%
2013 Stock Option and Grant Plan, Employees | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock options exercised | $	$ 200,000	$ 200,000		$ 1,000,000	$ 300,000
2013 Stock Option and Grant Plan, Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				1 year
2013 Stock Option and Grant Plan, Non-Employees | Non-Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options issued (in shares)	0	0		0	0
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)						302,000
Founder Agreements | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued (in shares)			1,400,000
Number of non-employee founders | non-employee	2			2
Founder Agreements | Restricted Stock | Share-Based Compensation Award, Founder Awards, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued (in shares)			1,000,000
Founder Agreements | Restricted Stock | Share-Based Compensation Award, Founder Awards, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued (in shares)			400,000
Founder Agreements | Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
Founder Agreements | Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,036	$ 655	$ 2,389	$ 1,095
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	611	505	1,550	810
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 425	$ 150	$ 839	$ 285

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Activity (Details) - Restricted Stock shares in Thousands	6 Months Ended
	Jun. 30, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning unvested balance (in shares) | shares	94
Issued (in shares) | shares	0
Vested (in shares) | shares	(67)
Repurchased (in shares) | shares	(1)
Ending unvested balance (in shares) | shares	26
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning unvested balance (in dollars per share) | $ / shares	$ 0.07
Issued (in dollars per share) | $ / shares	0
Vested (in dollars per share) | $ / shares	0.08
Repurchased (in dollars per share) | $ / shares	0.37
Ending unvested balance (in dollars per share) | $ / shares	$ 0.02

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions (Details) - Employee Stock Option	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.00%	1.50%	2.10%	1.50%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Expected volatility	73.60%	70.50%	73.60%	69.50%

Stock-Based Compensation - St38

Stock-Based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning outstanding balance (in shares) | shares	4,290
Granted (in shares) | shares	537
Exercised (in shares) | shares	(60)
Cancelled or forfeited (in shares) | shares	(104)
Ending oustanding balance (in shares) | shares	4,663	4,290
Vested and expected to vest (in shares) | shares	4,663
Exercisable (in shares) | shares	1,675
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning outstanding balance (in dollars per share) | $ / shares	$ 3.95
Granted (in dollars per share) | $ / shares	18.26
Exercised (in dollars per share) | $ / shares	2.49
Cancelled or forfeited (in dollars per share) | $ / shares	6.24
Ending outstanding balance (in dollars per share) | $ / shares	5.56	$ 3.95
Vested and expected to vest (in dollars per share) | $ / shares	5.56
Exercisable (in dollars per share) | $ / shares	$ 1.97
Remaining contractual life, outstanding	8 years 2 months 19 days	8 years 8 months 12 days
Remaining contractual life, vested and expected to vest	8 years 2 months 19 days
Remaining contractual life, exercisable	7 years 7 months 2 days
Aggregate intrinsic value, outstanding | $	$ 41,720,000	$ 29,269,000
Aggregate intrinsic value, vested and expected to vest | $	41,720,000
Aggregate intrinsic value, exercisable | $	$ 20,199,000

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2017USD ($)	Aug. 31, 2016change
Operating Loss Carryforwards [Line Items]
Number of previous ownership changes | change						3
Provision for income taxes	$ 1,104	$ 0	$ 1,104	$ 0
Scenario, Forecast | Minimum
Operating Loss Carryforwards [Line Items]
Federal and state tax liabilities					$ 16,000
Scenario, Forecast | Maximum
Operating Loss Carryforwards [Line Items]
Federal and state tax liabilities					$ 18,000

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2017	Jul. 31, 2016
Celegene Collaborative Arrangement
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement		$ 225
Convertible preferred stock (Series B-1) | Celegene Collaborative Arrangement
Related Party Transaction [Line Items]
Issuances of convertible preferred stock (in shares)		10,448,100
Issuances of convertible preferred stock		$ 36.1
IPO
Related Party Transaction [Line Items]
Stock converted upon completion of IPO (in shares)	22,300,000
Proceeds from IPO, net of discounts, commissions, and other offering expenses	$ 106.4
Celgene Corporation | Celgene Collaboration Agreement | Celegene Collaborative Arrangement
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement		$ 225
Celgene Corporation | Celgene Collaboration Agreement | Convertible preferred stock (Series B-1) | Celegene Collaborative Arrangement
Related Party Transaction [Line Items]
Issuances of convertible preferred stock (in shares)		10,448,100
Issuances of convertible preferred stock		$ 36.1
Celgene Corporation | IPO | Celgene Collaboration Agreement | Common Stock
Related Party Transaction [Line Items]
Stock converted upon completion of IPO (in shares)	2,831,463
Affiliated Entity | Celgene Corporation | IPO | Celgene Collaboration Agreement | Common Stock
Related Party Transaction [Line Items]
Sale of stock, number of shares issued (in shares)	625,000
Sale of stock, price per share (USD per share)	$ 16
Proceeds from IPO, net of discounts, commissions, and other offering expenses	$ 10

Net Loss per Share (Details)

Net Loss per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	4,689	23,096
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	4,663	3,178
Unvested restricted common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	26	466
Series A convertible preferred stock | Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	0	12,737
Series B convertible preferred stock | Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	0	6,715