Jounce Therapeutics (JNCE) 10-Q 6 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 01, 2020
Document and Entity Information [Abstract]
Entity Registrant Name	Jounce Therapeutics, Inc.
Entity Central Index Key	0001640455
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		34,053,091
Entity Shell Company	false
Entity Current Reporting Status	Yes

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 74,991	$ 53,241
Short-term investments	71,975	115,602
Prepaid expenses and other current assets	5,393	4,854
Total current assets	152,359	173,697
Property and equipment, net	9,755	10,672
Long-term investments	1,608	1,601
Operating lease right-of-use asset	16,946	17,615
Other non-current assets	2,282	2,297
Total assets	182,950	205,882
Current liabilities:
Accounts payable	3,722	2,460
Accrued expenses	7,543	8,907
Operating lease liability, current	2,991	2,901
Other current liabilities	39	132
Total current liabilities	14,295	14,400
Operating lease liability, net of current portion	16,111	16,889
Total liabilities	30,406	31,289
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value: 5,000 shares authorized at March 31, 2020 and December 31, 2019; no shares issued or outstanding at March 31, 2020 or December 31, 2019	0	0
Common stock, $0.001 par value: 160,000 shares authorized at March 31, 2020 and December 31, 2019; 34,049 and 33,738 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	34	34
Additional paid-in capital	285,968	281,664
Accumulated other comprehensive income	144	54
Accumulated deficit	(133,602)	(107,159)
Total stockholders’ equity	152,544	174,593
Total liabilities and stockholders’ equity	$ 182,950	$ 205,882

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock (in dollars per share)	$ 0.001	$ 0.001
Preferred stock shares authorized (in shares)	5,000,000	5,000,000
Preferred stock shares issued (in shares)	0	0
Preferred stock shares outstanding (in shares)	0	0
Common stock (in dollars per share)	$ 0.001	$ 0.001
Common stock shares authorized (in shares)	160,000,000	160,000,000
Common stock shares issued (in shares)	34,049,000	33,738,000
Common stock shares outstanding (in shares)	34,049,000	33,738,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue:
License and collaboration revenue—related party	$ 0	$ 10,981
Operating expenses:
Research and development	19,646	17,280
General and administrative	7,539	7,192
Total operating expenses	27,185	24,472
Operating loss	(27,185)	(13,491)
Other income, net	750	1,126
Loss before provision for income taxes	(26,435)	(12,365)
Provision for income taxes	8	12
Net loss	$ (26,443)	$ (12,377)
Net loss per share, basic and diluted (in dollars per share)	$ (0.78)	$ (0.38)
Weighted-average common shares outstanding, basic and diluted (in shares)	34,029	32,959
Comprehensive loss:
Net loss	$ (26,443)	$ (12,377)
Other comprehensive income:
Unrealized gain on available-for-sale securities	90	129
Comprehensive loss	$ (26,353)	$ (12,248)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance, common stock (in shares) at Dec. 31, 2018		32,941
Beginning balance at Dec. 31, 2018	$ 104,129	$ 33	$ 268,081	$ (78)	$ (163,907)
Exercises of common stock options (in shares)	24
Exercises of common stock options	$ 69		69
Vesting of restricted stock awards and restricted stock units (in shares)		2
Vesting of restricted stock units	7		7
Stock-based compensation expense	2,542		2,542
Other comprehensive income (loss)	129			129
Net loss	(12,377)				(12,377)
Ending balance (in shares) at Mar. 31, 2019		32,967
Ending balance at Mar. 31, 2019	$ 94,424	$ 33	270,699	51	(176,359)
Beginning balance, common stock (in shares) at Dec. 31, 2019	33,738	33,738
Beginning balance at Dec. 31, 2019	$ 174,593	$ 34	281,664	54	(107,159)
Issuance of common stock from at the market offering, net of issuance costs (in shares)		201
Issuance of common stock from at the market offering, net of issuance costs	$ 1,648		1,648
Exercises of common stock options (in shares)	9
Exercises of common stock options	$ 38		38
Vesting of restricted stock awards and restricted stock units (in shares)		101
Stock-based compensation expense	2,618		2,618
Other comprehensive income (loss)	90			90
Net loss	$ (26,443)				(26,443)
Ending balance (in shares) at Mar. 31, 2020	34,049	34,049
Ending balance at Mar. 31, 2020	$ 152,544	$ 34	$ 285,968	$ 144	$ (133,602)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net loss	$ (26,443)	$ (12,377)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,618	2,542
Depreciation expense	938	960
Net amortization of premiums and discounts on investments	(84)	(474)
Other non-cash items	19	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(543)	(2,596)
Other non-current assets	18	(103)
Accounts payable	1,407	771
Accrued expenses and other current liabilities	(1,457)	(941)
Deferred revenue—related party	0	(10,981)
Other liabilities	(19)	16
Net cash used in operating activities	(23,546)	(23,183)
Investing activities:
Purchases of investments	(19,856)	(62,019)
Proceeds from maturities of investments	63,650	77,508
Purchases of property and equipment	(50)	(109)
Net cash provided by investing activities	43,744	15,380
Financing activities:
Proceeds from at the market offering, net of issuance costs	1,514	0
Proceeds from exercise of stock options	38	69
Net cash provided by financing activities	1,552	69
Net increase (decrease) in cash, cash equivalents and restricted cash	21,750	(7,734)
Cash, cash equivalents and restricted cash, beginning of period	54,511	49,176
Cash, cash equivalents and restricted cash, end of period	76,261	41,442
Non-cash investing and financing activities:
Purchases of property and equipment in accounts payable and accrued expenses	0	20
Supplemental cash flow information:
Cash paid for lease liabilities	$ 1,090	$ 1,060

Nature of Business

Nature of Business	3 Months Ended
	Mar. 31, 2020
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 provide long-lasting benefits to patients. The Company is subject to a number of risks similar to those of other clinical-stage 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. As of March 31, 2020 , the Company had cash, cash equivalents and investments of $148.6 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 12 months from May 6, 2020 , 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, collaborations, licensing arrangements and strategic alliances.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
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 March 31, 2020 and December 31, 2019 , and for the three months ended March 31, 2020 and 2019 , 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”) as found in the Accounting Standards Codification (“ASC”) of the Financial Accounting Standards Board (“FASB”) 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, 2019 filed with the SEC on February 27, 2020 (the “Annual Report on Form 10-K”). The information presented in the condensed consolidated financial statements and related notes as of March 31, 2020 , and for the three months ended March 31, 2020 and 2019 , is unaudited. The December 31, 2019 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 three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 , 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. 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, 2019 , and the notes thereto, which are included in the Annual Report on Form 10-K. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2020 . 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, accrued expenses, stock-based compensation expense and income taxes. 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 June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This guidance was originally effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption was permitted. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates , whereby the effective date of this standard for smaller reporting companies was deferred to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and early adoption is still permitted. Accordingly, the Company will now adopt this standard effective January 1, 2023, and it is currently evaluating the potential impact that ASU 2016-13 may have on the consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-13 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments in this update are able to be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. Accordingly, the Company adopted ASU 2018-15 effective January 1, 2020, and it elected to apply this guidance on a prospective basis. There was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”) when the counterparty is a customer. In addition, ASU 2018-18 adds unit-of-account guidance to ASC Topic 808, Collaborative Arrangements , in order to align this guidance with ASC 606 and also precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-18 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities when investment ownership changes. In addition, ASU 2019-12 simplifies the accounting for the interim period effects of changes in tax laws or rates and transactions that result in a step-up in the tax basis of goodwill. While this guidance is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, early adoption is permitted. Consequently, the Company elected to early adopt ASU 2019-12 effective January 1, 2020. Due to the adoption of this guidance, the Company did not record an intraperiod tax allocation to other comprehensive income for the three months ended March 31, 2020 . In accordance with ASU 2019-12, the Company has applied the new provisions related to the intraperiod tax allocation on a prospective basis.

Celgene Agreements

Celgene Agreements	3 Months Ended
	Mar. 31, 2020
Research and Development [Abstract]
Celgene Agreements	Celgene Agreements Celgene License Agreement On July 22, 2019, the Company entered into a License Agreement (the “Celgene License Agreement”) with Celgene. Pursuant to the Celgene License Agreement, the Company granted to Celgene a worldwide and exclusive license to develop, manufacture and commercialize JTX-8064 and certain derivatives thereof (an “Initial Licensed Compound”), as well as any antibody (other than the Initial Licensed Compound) or other biologic controlled by the Company as of July 22, 2019 that is specifically directed to the LILRB2 receptor (“LILRB2”) (the “Licensed Compounds”). In November 2019, Bristol-Myers Squibb Company (“BMS”) completed its acquisition of Celgene, and Celgene is now a wholly-owned subsidiary of BMS. The Celgene License Agreement provides Celgene with the sole right, at its sole cost and expense, to develop, seek regulatory approval for, manufacture and commercialize the Licensed Compounds and any product that comprises a Licensed Compound (each a “Licensed Product”) for all uses and purposes. Celgene is obligated to use commercially reasonable efforts to develop, seek regulatory approval for and commercialize at least one Licensed Product comprising or incorporating the Initial Licensed Compound (any such Licensed Product, an “Initial Licensed Product”). During the term of the license, the Company is prohibited from developing, manufacturing or commercializing any product that contains an antibody or other biologic that is specifically directed to LILRB2 or any related antibody or related biologic. Milestone and Royalties Under the terms of the Celgene License Agreement, Celgene paid the Company a one -time, non-refundable upfront payment of $50.0 million in July 2019. The Company is also entitled to receive payments from Celgene upon the achievement of specified clinical, regulatory and sales milestones for the first Initial Licensed Product to achieve such milestones, including potential clinical and regulatory milestone payments up to an aggregate total of $180.0 million and potential sales milestone payments up to an aggregate total of $300.0 million . The Company is also eligible to receive royalties at percentage rates ranging from mid-single-digits to low-double-digits, based on future annual net sales of the Initial Licensed Products, on an Initial Licensed Product-by-Initial Licensed Product and country-by-country basis until the later of (i) the date on which there are no longer any valid composition of matter or method of use claims within the Company’s patents or patents jointly owned by the Company and Celgene related to the Initial Licensed Product in such country and (ii) the twelve-year anniversary of the date of the first commercial sale of the first Initial Licensed Product in such country (the “Royalty Term”). Royalty payments may be reduced in specified circumstances, including payments required to be made by Celgene to third parties to acquire patent rights, up to an aggregate minimum floor, or may be reduced upon the occurrence of certain specified events, including certain compulsory licenses, or if associated with a Licensed Product that is not an Initial Licensed Product. Termination Unless terminated earlier in accordance with its terms, the Celgene License Agreement provides that it will expire (i) on an Initial Licensed Product-by-Initial Licensed Product and country-by-country basis on the date of the expiration of the Royalty Term with respect to such Initial Licensed Product in such country and (ii) in its entirety upon the expiration of all applicable Royalty Terms with respect to the Initial Licensed Products in all countries, following which the applicable licenses under the License Agreement will become fully paid-up, perpetual, irrevocable and royalty-free. Celgene may terminate the License Agreement for convenience, in its sole discretion, in its entirety or on a Licensed Product-by-Licensed Product or country-by-country basis, at any time with prior written notice to the Company. The License Agreement may be terminated in its entirety or on a Licensed Product-by-Licensed Product or country-by-country basis by either the Company or Celgene upon the uncured material breach of the other party. If the material breach relates solely to a particular Licensed Product, the non-breaching party may only terminate the License Agreement with respect to such Licensed Product. Either the Company or Celgene may terminate the License Agreement in the event of the bankruptcy or insolvency of the other party. The License Agreement provides that upon termination by Celgene for material breach with respect for a Licensed Product, Celgene will be released from its development, manufacturing and commercialization obligations with respect to such Licensed Product. Upon termination by the Company due to Celgene’s material breach or by Celgene for convenience, the licenses granted by the Company under the License Agreement will terminate and Celgene will grant to the Company, subject to negotiation regarding economic terms, a non-exclusive, worldwide license to develop, manufacture and commercialize the terminated Licensed Products. Accounting Analysis Identification of the Contract(s) The Company assessed the Celgene License Agreement and concluded that it represents a contract with a customer within the scope of ASC 606. Identification of Promises and Performance Obligations The Company determined that the Celgene License Agreement contains the following promises: (i) delivery of a worldwide and exclusive license to develop, manufacture and commercialize an Initial Licensed Compound and the Licensed Compounds (the “JTX-8064 License”) and (ii) provision of certain transition activities, specifically outlined within the Celgene License Agreement, related to the delivery of the JTX-8064 License (the “Transition Activities”). The Company also evaluated certain other optional activities outlined within the Celgene License Agreement and concluded that none convey a material right to Celgene. Accordingly, these options are not considered to be promises within the Celgene License Agreement. The Company assessed the above promises and concluded that the JTX-8064 License is both capable of being distinct and distinct within the context of the Celgene License Agreement. The Company also assessed its promise to perform the Transition Activities and concluded that it was both quantitatively and qualitatively immaterial in the context of the Celgene License Agreement. Accordingly, the Company did not assess the Transition Activities as a performance obligation. Based upon this evaluation, the Company concluded that its promise to deliver the JTX-8064 License represents the sole performance obligation in the Celgene License Agreement. Determination of Transaction Price As noted above, the Company received a non-refundable upfront payment of $50.0 million upon the execution of the Celgene License Agreement. This upfront payment represents an element of fixed consideration under the Celgene License Agreement. The Company also evaluated as possible variable consideration the milestones and royalties discussed above. With respect to clinical and regulatory milestones, based upon the high degree of uncertainty and risk associated with these potential payments, the Company concluded that all such amounts should be fully constrained as it is not probable that a significant reversal in the amount of cumulative revenue recognized will not occur. As for royalties and sales milestones, the Company determined that the royalties and milestones relate solely to the JTX-8064 License, which is a license of intellectual property (“IP”). Accordingly, the Company did not include any potential royalty or sales milestone amounts in the initial transaction price, and the Company will not recognize revenue related to these royalties and sales milestones until the associated sales occur and relevant thresholds are met. Based upon the above considerations, the Company concluded that the initial transaction price associated with the Celgene License Agreement consists solely of the upfront payment of $50.0 million . Allocation of Transaction Price to Performance Obligations As the Company’s promise to deliver the JTX-8064 License represents the sole performance obligation in the Celgene License Agreement, the entirety of the $50.0 million transaction price has been allocated to this performance obligation. Recognition of Revenue The Company determined that the JTX-8064 License is a functional license as the underlying IP has significant standalone functionality. In addition, the Company determined that the JTX-8064 License represents a right to use certain of the Company’s IP as it exists at a point in time. Finally, the Company determined that July 22, 2019 represents (i) the date at which the Company made available the IP to Celgene and (ii) the beginning of the period during which Celgene is able to use and benefit from its right to use the IP. Based upon these considerations, the Company recognized $50.0 million of license revenue during the three months ended September 30, 2019. The Company has not received any milestone or royalty payments under the Celgene License Agreement through March 31, 2020 . Celgene Collaboration Agreement In July 2016, the Company entered into a Master Research and Collaboration Agreement (the “Celgene Collaboration Agreement”) with Celgene. The primary goal of the collaboration was 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, vopratelimab, 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, the Company granted Celgene an exclusive option to develop and commercialize the Company’s product candidate JTX-4014, an anti-PD-1 antibody, which, upon exercise of such option, would have been a shared program to be used by both parties in and outside of the collaboration. The Company and Celgene terminated the Celgene Collaboration Agreement effective July 22, 2019. The Company received a non-refundable upfront cash payment of $225.0 million in July 2016 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 Company’s initial public offering (“IPO”). If Celgene had elected to exercise any of the program options, Celgene would have been required to pay the Company an option-exercise fee that varied by program. The initial research term of the collaboration was four years, which could have been extended, at Celgene’s option, annually for up to three additional years. Worldwide Development Cost and U.S. Operating Profit and Loss Sharing Prior to Celgene exercising any of its options, the Company was responsible for all research and development activities under the Celgene Collaboration Agreement. Upon the exercise of each program option, the parties would have entered into a co-development and co-commercialization agreement (the “Co-Co Agreements”) or, in the case of JTX-4014, a license agreement (the “JTX-4014 License Agreement”) to govern the development and commercialization of the applicable program. As part of the Celgene Collaboration Agreement, the parties agreed to the terms of the Co-Co Agreements and the JTX-4014 License Agreement that would have been executed upon Celgene’s exercise of any option. Milestones and Royalties Under the Co-Co Agreements and the JTX-4014 License Agreement, Celgene would have been required to pay the Company for specified development, regulatory and commercial milestones, if achieved, across all collaboration programs. Development milestones were payable on the initiation of certain clinical trials, regulatory approval milestones were payable upon regulatory approval in the United States and outside the United States and commercial milestones were payable upon achievement of specified aggregate product sales outside the United States for each program. The Company was also eligible to receive royalties on product sales outside the United States. Accounting Analysis Identification of the Contract(s) The Company assessed the Celgene Collaboration Agreement and concluded that it represented a contract with a customer within the scope of ASC 606. The Company also concluded that each of the Co-Co Agreements and the JTX-4014 License Agreement, if any had been executed, would have represented separate contracts apart from the Celgene Collaboration Agreement. Identification of Promises and Performance Obligations The Company determined that the Celgene Collaboration Agreement contained the following promises: (i) research and development services for vopratelimab (“Vopratelimab Research Services”), (ii) research and development services for 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 services associated with target screening (“Target Screening Services”), (v) non-transferable, limited sub-licensable and non-exclusive licenses to use the Company’s intellectual property and the Company’s rights in the collaboration intellectual property to conduct certain activities, on a program-by-program basis (the “Research Licenses”), (vi) various record-keeping and reporting requirements on a program-by-program basis, (vii) exclusivity provisions with respect to each Collaboration Exclusive Target and biologics binding to such Collaboration Exclusive Targets and (viii) establishment of and participation in a joint steering committee (the “JSC”) and a joint patent committee (the “JPC”). The Company also evaluated the six program options as well as the research term extension options and concluded that none conveyed a material right to Celgene. Accordingly, neither the program options nor the research term extension options were considered to be promises within the Celgene Collaboration Agreement. The Company assessed the above promises and concluded that each of the Vopratelimab Research Services, JTX-4014 Research Services, Lead and Other Programs Research Services and Target Screening Services were both capable of being distinct and distinct within the context of the Celgene Collaboration Agreement. Therefore, the Company concluded that each of the Vopratelimab Research Services, JTX-4014 Research Services, Lead and Other Programs Research Services and Target Screening Services represented separate performance obligations. The Company determined that the Research Licenses were not distinct within the context of the Celgene Collaboration Agreement as the Research Licenses allowed Celgene to evaluate the results of the research and development services performed by the Company and the right to perform its duties under the Celgene Collaboration Agreement, but did not provide Celgene with any commercialization rights. Celgene could only benefit from the Research Licenses in conjunction with the related research and development services. Accordingly, the Research Licenses related to vopratelimab, JTX-4014 and the Lead and Other Programs were combined with their respective research and development services performance obligations. Similarly, the Company also determined that the various record-keeping and reporting requirements related to each program and the exclusivity provisions with respect to each Collaboration Exclusive Target and biologics binding to such Collaboration Exclusive Targets were not distinct within the context of the Celgene Collaboration Agreement. Accordingly, the various record-keeping and reporting requirements on a program-by-program basis and the exclusivity provisions with respect to each Collaboration Exclusive Target and biologics binding to such Collaboration Exclusive Targets were combined with their respective research and development services performance obligations. Finally, the Company assessed its participation in the JSC and the JPC and concluded that it was both quantitatively and qualitatively immaterial in the context of the Celgene Collaboration Agreement. Accordingly, the Company did not assess its participation in the JSC and the JPC as a performance obligation. Determination of Transaction Price As noted above, the Company received a non-refundable upfront payment of $225.0 million upon the execution of the Celgene Collaboration Agreement. This upfront payment represented an element of fixed consideration under the Celgene Collaboration Agreement. Celgene also purchased 10,448,100 shares of Series B-1 convertible preferred stock (“Series B-1 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 Preferred Stock were sold at fair value. Therefore, the proceeds from the issuance of Series B-1 Preferred Stock did not impact the transaction price to be allocated to the performance obligations. The Company evaluated as possible variable consideration the milestones, royalties, development cost sharing and profit-sharing provisions discussed above. The Company concluded that none of these items represented variable consideration under the Celgene Collaboration Agreement as all such amounts were dependent upon the execution of a related Co-Co Agreement or the JTX-4014 License Agreement. The Co-Co Agreements and the JTX-4014 License Agreement, if any had been executed, would have represented separate contracts apart from the Celgene Collaboration Agreement. The Company also considered the existence of any significant financing component within the Celgene Collaboration Agreement given its upfront payment structure. Based upon this assessment, the Company concluded that any difference between the promised consideration and the cash selling price of the services under the Celgene Collaboration Agreement arose for reasons other than the provision of financing, and the difference between those amounts was proportional to the reason for the difference. Accordingly, the Company concluded that the upfront payment structure of the Celgene Collaboration Agreement did not result in the existence of a significant financing component. Based upon the above considerations, the Company concluded that the transaction price associated with the Celgene Collaboration Agreement consisted solely of the upfront payment of $225.0 million . Allocation of Transaction Price to Performance Obligations The Company allocated the transaction price to each performance obligation on a relative standalone selling price basis. For all performance obligations, the Company determined the standalone selling price using estimates of the costs to perform the research and development services, including expected internal and external costs for services and supplies, adjusted to reflect a reasonable profit margin. The total estimated cost of the research and development services reflected the nature of the services to be performed and the Company’s best estimate of the length of time required to perform the services. Recognition of Revenue Prior to the termination of the Celgene Collaboration Agreement, the Company was recognizing revenue over time as the services related to each performance obligation were rendered. The Company concluded that an input method under ASC 606 was a representative depiction of the transfer of services under the Celgene Collaboration Agreement. The method of measuring progress towards delivery of the services incorporated actual internal and external costs incurred, relative to total internal and external costs expected to be incurred to satisfy the performance obligations. The period over which total costs were estimated reflected the Company’s estimate of the period over which it would perform the research and development services to deliver a pre-defined data package to Celgene for each program subject to an option. The Company was recognizing revenue for each performance obligation over periods ranging from twelve months to four years. Changes in estimates of total internal and external costs expected to be incurred were recognized in the period of change as a cumulative catch-up adjustment. For the three months ended March 31, 2019 , the Company recognized collaboration revenue of $11.0 million under the Celgene Collaboration Agreement related to the $225.0 million upfront payment received in 2016. Following the termination of the Celgene Collaboration Agreement, which was effective July 22, 2019, the Company had no further performance obligations. Accordingly, all remaining deferred revenue related to the Celgene Collaboration Agreement was recognized during the three months ended September 30, 2019. Up through the termination of the Celgene Collaboration Agreement, the Company did not receive any option exercise, research term extension, milestone or royalty payments.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
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 March 31, 2020 were as follows (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs Money market funds, included in cash equivalents $ 65,991 $ 65,991 $ — $ — Investments: Corporate debt securities 33,366 — 33,366 — U.S. Treasuries 40,755 40,755 — — Government agency securities 8,462 — 8,462 — Totals $ 148,574 $ 106,746 $ 41,828 $ — Assets measured at fair value on a recurring basis as of December 31, 2019 were as follows (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs Money market funds, included in cash equivalents $ 50,242 $ 50,242 $ — $ — Investments: Corporate debt securities 48,300 — 48,300 — U.S. Treasuries 59,082 59,082 — — Government agency securities 12,820 — 12,820 — Totals $ 170,444 $ 109,324 $ 61,120 $ — There were no changes in valuation techniques during the three months ended March 31, 2020 or during the year ended December 31, 2019 . There were no liabilities measured at fair value on a recurring basis as of March 31, 2020 or December 31, 2019 .

Investments

Investments	3 Months Ended
	Mar. 31, 2020
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 as a component of stockholders’ equity until realized. Cash equivalents, short-term investments and long-term investments as of March 31, 2020 were comprised as follows (in thousands): March 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 65,991 $ — $ — $ 65,991 Corporate debt securities 31,825 5 (72 ) 31,758 U.S. Treasuries 40,594 161 — 40,755 Government agency securities 8,420 42 — 8,462 Total cash equivalents and short-term investments 146,830 208 (72 ) 146,966 Long-term investments: Corporate debt securities 1,600 8 — 1,608 Total long-term investments 1,600 8 — 1,608 Total cash equivalents and investments $ 148,430 $ 216 $ (72 ) $ 148,574 Cash equivalents, short-term investments and long-term investments as of December 31, 2019 were comprised as follows (in thousands): December 31, 2019 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 50,242 $ — $ — $ 50,242 Corporate debt securities 46,695 8 (4 ) 46,699 U.S. Treasuries 59,058 26 (2 ) 59,082 Government agency securities 12,796 24 — 12,820 Total cash equivalents and short-term investments 168,791 58 (6 ) 168,843 Long-term investments: Corporate debt securities 1,599 2 — 1,601 Total long-term investments 1,599 2 — 1,601 Total cash equivalents and investments $ 170,390 $ 60 $ (6 ) $ 170,444 As of March 31, 2020 and December 31, 2019 , the aggregate fair value of securities that were in an unrealized loss position for less than twelve months was $14.6 million and $28.3 million , respectively. As of both March 31, 2020 and December 31, 2019 , the aggregate fair value of securities that were in an unrealized loss position for more than twelve months was $2.0 million . As of March 31, 2020 , 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 March 31, 2020 . There were immaterial realized gains and losses on available-for-sale securities during the three months ended March 31, 2020 . There were no realized gains and losses on available-for-sale securities during the three months ended March 31, 2019 .

Restricted Cash

Restricted Cash	3 Months Ended
	Mar. 31, 2020
Cash and Cash Equivalents [Abstract]
Restricted Cash	Restricted Cash As of both March 31, 2020 and December 31, 2019 , the Company maintained non-current restricted cash of $1.3 million . This amount is included within “Other non-current assets” in the accompanying condensed consolidated balance sheets and is comprised solely of a letter of credit required pursuant to the lease for the Company’s corporate headquarters. The following table provides a reconciliation of cash, cash equivalents and restricted cash that sums to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): Three Months Ended Three Months Ended Beginning of Period End of Period Beginning of Period End of Period Cash and cash equivalents $ 53,241 $ 74,991 $ 47,906 $ 40,172 Restricted cash 1,270 1,270 1,270 1,270 Cash, cash equivalents and restricted cash $ 54,511 $ 76,261 $ 49,176 $ 41,442

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses as of March 31, 2020 and December 31, 2019 were comprised as follows (in thousands): March 31, December 31, 2020 2019 Employee compensation and benefits $ 2,388 $ 5,147 External research and professional services 4,937 3,639 Lab consumables and other 218 121 Total accrued expenses $ 7,543 $ 8,907

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Common Stock The Company is authorized to issue 160,000,000 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. On December 17, 2019, the Company entered into a Sales Agreement with Cowen and Company, LLC (“Cowen”) pursuant to which the Company may offer and sell shares of its common stock with an aggregate offering price of up to $50.0 million under an “at the market” offering program (the “ATM Offering”). The Sales Agreement provides that Cowen will be entitled to a sales commission equal to 3.0% of the gross sales price per share of all shares sold under the ATM Offering. From the initiation of the ATM Offering through March 31, 2020 , the Company has sold an aggregate of 648,845 shares at an average price of $8.54 per share for net proceeds of $5.2 million after deducting sales commissions and offering expenses. Preferred Stock The Company is authorized to issue 5,000,000 shares of undesignated preferred stock in one or more series. As of March 31, 2020 , no shares of preferred stock were issued or outstanding. Shares Reserved for Future Issuance As of March 31, 2020 and December 31, 2019 , the Company had reserved for future issuance the following number of shares of common stock (in thousands): March 31, December 31, 2020 2019 Shares reserved for vesting of restricted stock units 760 460 Shares reserved for exercises of outstanding stock options 6,643 5,735 Shares reserved for future issuance under the 2017 Stock Option and Incentive Plan 1,320 1,288 Total shares reserved for future issuance 8,723 7,483

Stock-based Compensation

Stock-based Compensation	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-based Compensation	Stock-based Compensation 2013 Stock Option and Grant Plan In February 2013, the board of directors adopted and the Company’s stockholders approved 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, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) 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 board of directors adopted and the Company’s stockholders approved the 2017 Stock Option and Incentive Plan (the “2017 Plan”). 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, RSAs, RSUs, 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 terms of awards, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2017 Plan. The Company initially registered on Form S-8 1,753,758 shares of common stock under the 2017 Plan, which was 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 st 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. Effective January 1, 2018, 2019 and 2020, 1,290,609 , 1,317,935 and 1,349,526 additional shares, respectively, were automatically added to the shares authorized for issuance under the 2017 Plan. As of March 31, 2020 , there were 1,320,488 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”). The Company initially reserved 302,000 shares of common stock for future issuance under the 2017 ESPP. The 2017 ESPP also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 ESPP on January 1, 2018 and each January 1 st thereafter through January 1, 2027. The number of shares added each year will be equal to the lesser of (i) 1% of the outstanding shares on the immediately preceding December 31 st , (ii) 603,000 shares or (iii) such amount as determined by the compensation committee of the board of directors. Effective January 1, 2018, 2019 and 2020, 322,652 , 329,483 and 337,381 additional shares, respectively, were automatically added to the shares authorized for issuance under the 2017 ESPP. No offering periods under the 2017 ESPP had been initiated as of March 31, 2020 . Stock-based Compensation Expense Total stock-based compensation expense recognized in the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2020 and 2019 was as follows (in thousands): Three Months Ended 2020 2019 Research and development $ 1,181 $ 1,097 General and administrative 1,437 1,445 Total stock-based compensation expense $ 2,618 $ 2,542 RSU Activity The Company has also granted RSUs to its employees under the 2017 Plan. The following table summarizes RSU activity for the three months ended March 31, 2020 (in thousands, except per share amounts): RSUs Weighted-Average Grant Date Fair Value per Share Unvested as of December 31, 2019 460 $ 5.61 Issued 408 $ 6.55 Vested (101 ) $ 4.40 Cancelled (7 ) $ 6.83 Unvested as of March 31, 2020 760 $ 6.27 The aggregate fair value of RSUs that vested during the three months ended March 31, 2020 , based upon the fair values of the stock underlying the RSUs on the day of vesting, was $0.8 million . No RSUs vested during the three months ended March 31, 2019 . As of March 31, 2020 , there was unrecognized stock-based compensation expense related to unvested RSUs of $3.7 million , which the Company expects to recognize over a weighted-average period of approximately 2.0 years . Stock Option Activity The fair value of stock options granted during the three months ended March 31, 2020 and 2019 was calculated on the date of grant using the following weighted-average assumptions: Three Months Ended 2020 2019 Risk-free interest rate 1.4 % 2.6 % Expected dividend yield — % — % Expected term (in years) 6.1 6.1 Expected volatility 71.4 % 68.9 % Using the Black-Scholes option pricing model, the weighted-average grant date fair value of stock options granted during the three months ended March 31, 2020 and 2019 was $4.23 per share and $2.77 per share, respectively. The following table summarizes stock option activity during the three months ended March 31, 2020 (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, 2019 5,735 $ 8.76 7.2 $ 18,959 Granted 957 $ 6.66 Exercised (9 ) $ 4.21 Cancelled (40 ) $ 9.18 Outstanding at March 31, 2020 6,643 $ 8.46 7.3 $ 5,855 Exercisable at March 31, 2020 3,845 $ 7.69 6.2 $ 5,264 The aggregate intrinsic value of stock options exercised during each of the three months ended March 31, 2020 and 2019 was less than $0.1 million . As of March 31, 2020 , there was unrecognized stock-based compensation expense related to unvested stock options of $14.8 million , which the Company expects to recognize over a weighted-average period of approximately 2.6 years .

Related-party Transactions

Related-party Transactions	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Related-party Transactions	Related-party Transactions In July 2019, the Company entered into the Celgene License Agreement under which it received a non-refundable upfront payment of $50.0 million from Celgene. 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 convertible preferred stock for $36.1 million . These shares of Series B-1 convertible preferred stock converted into 2,831,463 shares of common stock upon the completion of the 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 . As of both March 31, 2020 and December 31, 2019 , the Company had recorded $0.7 million of reimbursable expenses due from Celgene within prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets. As discussed within Note 3, “Celgene Agreements”, BMS completed its acquisition of Celgene in November 2019, and Celgene is now a wholly-owned subsidiary of BMS.

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share For purposes of the diluted net loss per share calculation, outstanding stock options, unvested RSAs and unvested RSUs are considered to be potentially dilutive securities, however the following weighted-average amounts were excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive (in thousands): Three Months Ended 2020 2019 Outstanding stock options 6,339 5,516 Unvested RSAs — 6 Unvested RSUs 624 590 Total 6,963 6,112

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements as of March 31, 2020 and December 31, 2019 , and for the three months ended March 31, 2020 and 2019 , 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”) as found in the Accounting Standards Codification (“ASC”) of the Financial Accounting Standards Board (“FASB”) 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, 2019 filed with the SEC on February 27, 2020 (the “Annual Report on Form 10-K”). The information presented in the condensed consolidated financial statements and related notes as of March 31, 2020 , and for the three months ended March 31, 2020 and 2019 , is unaudited. The December 31, 2019 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 three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 , 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. 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, accrued expenses, stock-based compensation expense and income taxes. 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 June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This guidance was originally effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption was permitted. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates , whereby the effective date of this standard for smaller reporting companies was deferred to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and early adoption is still permitted. Accordingly, the Company will now adopt this standard effective January 1, 2023, and it is currently evaluating the potential impact that ASU 2016-13 may have on the consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-13 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments in this update are able to be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. Accordingly, the Company adopted ASU 2018-15 effective January 1, 2020, and it elected to apply this guidance on a prospective basis. There was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”) when the counterparty is a customer. In addition, ASU 2018-18 adds unit-of-account guidance to ASC Topic 808, Collaborative Arrangements , in order to align this guidance with ASC 606 and also precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-18 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities when investment ownership changes. In addition, ASU 2019-12 simplifies the accounting for the interim period effects of changes in tax laws or rates and transactions that result in a step-up in the tax basis of goodwill. While this guidance is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, early adoption is permitted. Consequently, the Company elected to early adopt ASU 2019-12 effective January 1, 2020. Due to the adoption of this guidance, the Company did not record an intraperiod tax allocation to other comprehensive income for the three months ended March 31, 2020 . In accordance with ASU 2019-12, the Company has applied the new provisions related to the intraperiod tax allocation on a prospective basis.
Fair Value Measurement Policy	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)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value	Assets measured at fair value on a recurring basis as of March 31, 2020 were as follows (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs Money market funds, included in cash equivalents $ 65,991 $ 65,991 $ — $ — Investments: Corporate debt securities 33,366 — 33,366 — U.S. Treasuries 40,755 40,755 — — Government agency securities 8,462 — 8,462 — Totals $ 148,574 $ 106,746 $ 41,828 $ — Assets measured at fair value on a recurring basis as of December 31, 2019 were as follows (in thousands): Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs Money market funds, included in cash equivalents $ 50,242 $ 50,242 $ — $ — Investments: Corporate debt securities 48,300 — 48,300 — U.S. Treasuries 59,082 59,082 — — Government agency securities 12,820 — 12,820 — Totals $ 170,444 $ 109,324 $ 61,120 $ —

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities by Security Type	Cash equivalents, short-term investments and long-term investments as of March 31, 2020 were comprised as follows (in thousands): March 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 65,991 $ — $ — $ 65,991 Corporate debt securities 31,825 5 (72 ) 31,758 U.S. Treasuries 40,594 161 — 40,755 Government agency securities 8,420 42 — 8,462 Total cash equivalents and short-term investments 146,830 208 (72 ) 146,966 Long-term investments: Corporate debt securities 1,600 8 — 1,608 Total long-term investments 1,600 8 — 1,608 Total cash equivalents and investments $ 148,430 $ 216 $ (72 ) $ 148,574 Cash equivalents, short-term investments and long-term investments as of December 31, 2019 were comprised as follows (in thousands): December 31, 2019 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents and short-term investments: Money market funds, included in cash equivalents $ 50,242 $ — $ — $ 50,242 Corporate debt securities 46,695 8 (4 ) 46,699 U.S. Treasuries 59,058 26 (2 ) 59,082 Government agency securities 12,796 24 — 12,820 Total cash equivalents and short-term investments 168,791 58 (6 ) 168,843 Long-term investments: Corporate debt securities 1,599 2 — 1,601 Total long-term investments 1,599 2 — 1,601 Total cash equivalents and investments $ 170,390 $ 60 $ (6 ) $ 170,444

Restricted Cash (Tables)

Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2020
Cash and Cash Equivalents [Abstract]
Schedule of Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash that sums to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): Three Months Ended Three Months Ended Beginning of Period End of Period Beginning of Period End of Period Cash and cash equivalents $ 53,241 $ 74,991 $ 47,906 $ 40,172 Restricted cash 1,270 1,270 1,270 1,270 Cash, cash equivalents and restricted cash $ 54,511 $ 76,261 $ 49,176 $ 41,442
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash that sums to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): Three Months Ended Three Months Ended Beginning of Period End of Period Beginning of Period End of Period Cash and cash equivalents $ 53,241 $ 74,991 $ 47,906 $ 40,172 Restricted cash 1,270 1,270 1,270 1,270 Cash, cash equivalents and restricted cash $ 54,511 $ 76,261 $ 49,176 $ 41,442

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses as of March 31, 2020 and December 31, 2019 were comprised as follows (in thousands): March 31, December 31, 2020 2019 Employee compensation and benefits $ 2,388 $ 5,147 External research and professional services 4,937 3,639 Lab consumables and other 218 121 Total accrued expenses $ 7,543 $ 8,907

Common Stock and Preferred St_2

Common Stock and Preferred Stock (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Schedule of Stock by Class	As of March 31, 2020 and December 31, 2019 , the Company had reserved for future issuance the following number of shares of common stock (in thousands): March 31, December 31, 2020 2019 Shares reserved for vesting of restricted stock units 760 460 Shares reserved for exercises of outstanding stock options 6,643 5,735 Shares reserved for future issuance under the 2017 Stock Option and Incentive Plan 1,320 1,288 Total shares reserved for future issuance 8,723 7,483

Stock-based Compensation (Table

Stock-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expense	Total stock-based compensation expense recognized in the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2020 and 2019 was as follows (in thousands): Three Months Ended 2020 2019 Research and development $ 1,181 $ 1,097 General and administrative 1,437 1,445 Total stock-based compensation expense $ 2,618 $ 2,542
Schedule of Restricted Stock Activity	The Company has also granted RSUs to its employees under the 2017 Plan. The following table summarizes RSU activity for the three months ended March 31, 2020 (in thousands, except per share amounts): RSUs Weighted-Average Grant Date Fair Value per Share Unvested as of December 31, 2019 460 $ 5.61 Issued 408 $ 6.55 Vested (101 ) $ 4.40 Cancelled (7 ) $ 6.83 Unvested as of March 31, 2020 760 $ 6.27
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The fair value of stock options granted during the three months ended March 31, 2020 and 2019 was calculated on the date of grant using the following weighted-average assumptions: Three Months Ended 2020 2019 Risk-free interest rate 1.4 % 2.6 % Expected dividend yield — % — % Expected term (in years) 6.1 6.1 Expected volatility 71.4 % 68.9 %
Schedule of Stock Options, Activity	The following table summarizes stock option activity during the three months ended March 31, 2020 (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, 2019 5,735 $ 8.76 7.2 $ 18,959 Granted 957 $ 6.66 Exercised (9 ) $ 4.21 Cancelled (40 ) $ 9.18 Outstanding at March 31, 2020 6,643 $ 8.46 7.3 $ 5,855 Exercisable at March 31, 2020 3,845 $ 7.69 6.2 $ 5,264

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share	For purposes of the diluted net loss per share calculation, outstanding stock options, unvested RSAs and unvested RSUs are considered to be potentially dilutive securities, however the following weighted-average amounts were excluded from the calculation of diluted net loss per share because their effect would be anti-dilutive (in thousands): Three Months Ended 2020 2019 Outstanding stock options 6,339 5,516 Unvested RSAs — 6 Unvested RSUs 624 590 Total 6,963 6,112

Nature of Business (Details)

Nature of Business (Details) - USD ($) $ in Millions	May 06, 2020	Mar. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash, cash equivalents, and marketable securities		$ 148.6
Scenario, Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Duration of funding requirement	12 months

Celgene Agreements - Narrative

Celgene Agreements - Narrative (Details) $ in Thousands	Jul. 22, 2019USD ($)	Feb. 01, 2017shares	Jul. 31, 2016USD ($)deliverablecustomer_programshares	Mar. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License and collaboration revenue—related party				$ 0		$ 10,981
Celgene Corporation | Common Stock | Celgene Collaboration Agreement | IPO
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Stock converted upon completion of IPO (in shares) | shares		2,831,463
Celgene License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront payment received for research agreement	$ 50,000
Aggregate revenue for clinical and regulatory milestones	180,000
Aggregate revenue for sales milestones	$ 300,000
License and collaboration revenue—related party					$ 50,000
Celegene Collaborative Arrangement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront payment received for research agreement			$ 225,000
License and collaboration revenue—related party						$ 11,000
Number of early-stage programs | customer_program			4
Initial research term			4 years
Potential addition to research term			3 years
Number of program options | deliverable			6
Celegene Collaborative Arrangement | Convertible preferred stock (Series B-1)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuances of convertible preferred stock			$ 36,100
Issuances of convertible preferred stock (in shares) | shares			10,448,100
Celegene Collaborative Arrangement | Celgene Corporation | Celgene Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable upfront payment received for research agreement			$ 225,000
Celegene Collaborative Arrangement | Celgene Corporation | Convertible preferred stock (Series B-1) | Celgene Collaboration Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Issuances of convertible preferred stock			$ 36,100
Issuances of convertible preferred stock (in shares) | shares			10,448,100

Celgene Agreements - Performanc

Celgene Agreements - Performance Obligations (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2016-08-01 - Celegene Collaborative Arrangement	Mar. 31, 2020
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance period for unit of accounting	12 months
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance period for unit of accounting	4 years

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Measurements, Recurring
Investments:
Totals	$ 148,574,000	$ 170,444,000
Liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investments:
Totals	106,746,000	109,324,000
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investments:
Totals	41,828,000	61,120,000
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investments:
Totals	0	0
Corporate debt securities | Fair Value, Measurements, Recurring
Investments:
Available-for-sale debt securities, fair value	33,366,000	48,300,000
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	33,366,000	48,300,000
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	40,755,000	59,082,000
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	40,755,000	59,082,000
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	8,462,000	12,820,000
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	0	0
Government agency securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investments:
Available-for-sale debt securities, fair value	8,462,000	12,820,000
Government agency securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investments:
Available-for-sale debt securities, fair value	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	65,991,000	50,242,000
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	65,991,000	50,242,000
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	65,991,000	50,242,000
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

Investments - Available-for-sal

Investments - Available-for-sale Securities by Security Type (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Unrealized Gains	$ 216	$ 60
Unrealized Losses	(72)	(6)
Cash equivalents, short-term and long-term investments, carrying value	148,430	170,390
Cash equivalents, short-term and long-term investments, fair vale disclosure	148,574	170,444
Short-term Investments
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Unrealized Gains	208	58
Unrealized Losses	(72)	(6)
Total cash equivalents and short-term investments, carrying value	146,830	168,791
Total cash equivalents and short-term investments, fair value	146,966	168,843
Short-term Investments | Corporate debt securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Available-for-sale debt securities, amortized cost basis	31,825	46,695
Unrealized Gains	5	8
Unrealized Losses	(72)	(4)
Available-for-sale debt securities, fair value	31,758	46,699
Short-term Investments | US Treasury Securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Available-for-sale debt securities, amortized cost basis	40,594	59,058
Unrealized Gains	161	26
Unrealized Losses	0	(2)
Available-for-sale debt securities, fair value	40,755	59,082
Short-term Investments | Government agency securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Available-for-sale debt securities, amortized cost basis	8,420	12,796
Unrealized Gains	42	24
Unrealized Losses	0	0
Available-for-sale debt securities, fair value	8,462	12,820
Long-term Investments
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Available-for-sale debt securities, amortized cost basis	1,600	1,599
Unrealized Gains	8	2
Unrealized Losses	0	0
Available-for-sale debt securities, fair value	1,608	1,601
Long-term Investments | Corporate debt securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Available-for-sale debt securities, amortized cost basis	1,600	1,599
Unrealized Gains	8	2
Unrealized Losses	0	0
Available-for-sale debt securities, fair value	1,608	1,601
Money market funds, included in cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalents at carrying value	65,991	50,242
Cash equivalents at fair value	$ 65,991	$ 50,242

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities in an unrealized loss position for less than twelve months	$ 14,600,000		$ 28,300,000
Aggregate fair value of securities in an unrealized position for more than twelve months	2,000,000		$ 2,000,000
Realized gains or losses on available-for-sale securities	$ 0	$ 0

Restricted Cash - Narrative (De

Restricted Cash - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Non-current restricted cash	$ 1.3	$ 1.3

Restricted Cash - Schedule of C

Restricted Cash - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 74,991	$ 53,241	$ 40,172	$ 47,906
Restricted cash	1,270	1,270	1,270	1,270
Cash, cash equivalents and restricted cash	$ 76,261	$ 54,511	$ 41,442	$ 49,176

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 2,388	$ 5,147
External research and professional services	4,937	3,639
Lab consumables and other	218	121
Total accrued expenses	$ 7,543	$ 8,907

Common Stock and Preferred St_3

Common Stock and Preferred Stock - Narrative (Details) $ / shares in Units, $ in Millions	Dec. 17, 2019USD ($)	Mar. 31, 2020USD ($)vote$ / sharesshares	Dec. 31, 2019shares
Subsidiary, Sale of Stock [Line Items]
Common stock shares authorized (in shares)		160,000,000	160,000,000
Common stock, votes per share | vote		1
Preferred stock shares authorized (in shares)		5,000,000	5,000,000
Preferred stock shares issued (in shares)		0	0
Preferred stock shares outstanding (in shares)		0	0
ATM Offering
Subsidiary, Sale of Stock [Line Items]
Aggregate offering price shares | $	$ 50
Sales commission percentage	3.00%
Sale of stock, number of shares issued (in shares)		648,845
Sale of stock, price per share (USD per share) | $ / shares		$ 8.54
Proceeds from IPO, net of discounts, commissions, and other offering expenses | $		$ 5.2

Common Stock and Preferred St_4

Common Stock and Preferred Stock - Shares Reserved for Future Issuance (Details) - shares	Mar. 31, 2020	Dec. 31, 2019	Jan. 31, 2017
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	8,723,000	7,483,000	1,753,758
Restricted Stock Units (RSUs)
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	760,000	460,000
Outstanding Employee Stock Options
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	6,643,000	5,735,000
Future Issuances from Employee Stock Options
Conversion of Stock [Line Items]
Common stock reserved for potential conversion (in shares)	1,320,000	1,288,000

Stock-based Compensation - Narr

Stock-based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2020	Jan. 01, 2019	Jan. 01, 2018	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jan. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)				8,723,000		7,483,000	1,753,758
Weighted average fair value of options granted (in dollars per share)				$ 4.23	$ 2.77
Intrinsic value of stock options exercised				$ 0.1	$ 0.1
Unrecognized stock-based compensation expense, options				$ 14.8
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)				1,320,488
Shares of common stock eligible to be purchased (in shares)				1,320,000		1,288,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock eligible to be purchased (in shares)				760,000		460,000
Aggregate fair value of awards vested in period				$ 0.8
Vested (in shares)				101,000	0
Unrecognized stock-based compensation expense, RSUs				$ 3.7
Remaining weighted average vesting period				2 years 11 days
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining weighted average vesting period				2 years 6 months 26 days
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
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%
Number of additional shares authorized (in shares)	1,349,526	1,317,935	1,290,609
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
Percent of outstanding shares able to be added each year							1.00%
Number of additional shares authorized (in shares)	337,381	329,483	322,652
Shares of common stock to determine number of additional shares (in shares)							603,000

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,618	$ 2,542
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,181	1,097
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,437	$ 1,445

Stock-based Compensation - RSU

Stock-based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
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)	460,000
Issued (in shares)	408,000
Vested (in shares)	(101,000)	0
Cancelled (in shares)	(7,000)
Ending unvested balance (in shares)	760,000
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)	$ 5.61
Issued (in dollars per share)	6.55
Vested (in dollars per share)	4.40
Cancelled (in dollars per share)	6.83
Ending unvested balance (in dollars per share)	$ 6.27

Stock-based Compensation - Weig

Stock-based Compensation - Weighted Average Assumptions (Details) - Employee Stock Option	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.40%	2.60%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	6 years 22 days	6 years 1 month 6 days
Expected volatility	71.40%	68.90%

Stock-based Compensation - St_2

Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning outstanding balance (in shares)	5,735
Granted (in shares)	957
Exercises of common stock options (in shares)	(9)	(24)
Cancelled or forfeited (in shares)	(40)
Ending outstanding balance (in shares)	6,643		5,735
Exercisable (in shares)	3,845
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)	$ 8.76
Granted (in dollars per share)	6.66
Exercised (in dollars per share)	4.21
Cancelled or forfeited (in dollars per share)	9.18
Ending outstanding balance (in dollars per share)	8.46		$ 8.76
Exercisable (in dollars per share)	$ 7.69
Remaining contractual life, outstanding	7 years 3 months 29 days		7 years 2 months 9 days
Remaining contractual life, exercisable	6 years 2 months 16 days
Aggregate intrinsic value, outstanding	$ 5,855		$ 18,959
Aggregate intrinsic value, exercisable	$ 5,264

Related-party Transactions (Det

Related-party Transactions (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 22, 2019	Feb. 01, 2017	Jul. 31, 2019	Jul. 31, 2016	Mar. 31, 2020	Dec. 31, 2019
Celgene License Agreement
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement	$ 50
Celegene Collaborative Arrangement
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement				$ 225
Celegene Collaborative Arrangement | Convertible preferred stock (Series B-1)
Related Party Transaction [Line Items]
Issuances of convertible preferred stock (in shares)				10,448,100
Issuances of convertible preferred stock				$ 36.1
Celgene License Agreement | Celgene License Agreement | Celgene Corporation
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement			$ 50
Reimbursable expenses due from Celgene					$ 0.7	$ 0.7
Celgene Collaboration Agreement | Celgene Corporation | Common Stock | IPO
Related Party Transaction [Line Items]
Stock converted upon completion of IPO (in shares)		2,831,463
Celgene Collaboration Agreement | Celgene Corporation | Common Stock | IPO | Affiliated Entity
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
Celgene Collaboration Agreement | Celegene Collaborative Arrangement | Celgene Corporation
Related Party Transaction [Line Items]
Non-refundable upfront payment received for research agreement				$ 225
Celgene Collaboration Agreement | Celegene Collaborative Arrangement | Celgene Corporation | Convertible preferred stock (Series B-1)
Related Party Transaction [Line Items]
Issuances of convertible preferred stock (in shares)				10,448,100
Issuances of convertible preferred stock				$ 36.1

Net Loss per Share Schedule of

Net Loss per Share Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	6,963	6,112
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	6,339	5,516
Unvested RSAs
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
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	624	590

Uncategorized Items - jnce-2020

Label	Element	Value
Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (75,000)
Accounting Standards Update 2016-02 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (75,000)