Surface Oncology (SURF) 10-Q 12 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 08, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	SURF
Entity Registrant Name	SURFACE ONCOLOGY, INC.
Entity Central Index Key	0001718108
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38459
Entity Tax Identification Number	46-5543980
Entity Address, Address Line One	50 Hampshire Street
Entity Address, Address Line Two	8th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	714-4096
Entity Common Stock, Shares Outstanding		28,321,999
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, $0.0001
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 56,419	$ 46,755
Marketable securities	33,665	58,406
Prepaid expenses and other current assets	3,209	2,765
Total current assets	93,293	107,926
Property and equipment, net	6,851	7,286
Operating lease right-of-use asset	29,310	14,858
Restricted cash	1,595	1,595
Other assets	166	28
Total assets	131,215	131,693
Current liabilities:
Accounts payable	733	3,384
Accrued expenses and other current liabilities	7,545	8,012
Deferred revenue - related party		4,916
Operating lease liability	5,101	2,962
Total current liabilities	13,379	19,274
Deferred revenue - related party, non-current		33,676
Operating lease liability, non-current	29,885	16,968
Convertible note payable, non-current	5,285	5,109
Other liabilities	1,100
Total liabilities	49,649	75,027
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, $0.0001 par value per share; 5,000,000 shares authorized at March 31, 2020 and December 31, 2019; no shares issued and outstanding at March 31, 2020 and December 31, 2019
Common stock, $0.0001 par value; 150,000,000 shares authorized at March 31, 2020 and December 31, 2019, respectively; 28,061,197 and 27,893,337 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	3	3
Additional paid-in capital	180,418	178,155
Accumulated other comprehensive income	170	103
Accumulated deficit	(99,025)	(121,595)
Total stockholders’ equity	81,566	56,666
Total liabilities and stockholders’ equity	$ 131,215	$ 131,693

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, authorized	5,000,000	5,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized	150,000,000	150,000,000
Common stock, issued	28,061,197	27,893,337
Common stock, outstanding	28,061,197	27,893,337

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Collaboration revenue - related party	$ 38,592	$ 14,434
Type of Revenue [Extensible List]	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember
Operating expenses:
Research and development	$ 11,288	$ 14,309
General and administrative	4,787	5,093
Total operating expenses	16,075	19,402
Income (loss) from operations	22,517	(4,968)
Interest and other income, net	53	769
Net income (loss)	$ 22,570	$ (4,199)
Net income (loss) per share attributable to common stockholders— basic	$ 0.81	$ (0.15)
Weighted average common shares outstanding— basic	27,977,145	27,825,698
Net income (loss) per share attributable to common stockholders— diluted	$ 0.74	$ (0.15)
Weighted average common shares outstanding— diluted	30,917,452	27,825,698
Comprehensive income (loss):
Net income (loss)	$ 22,570	$ (4,199)
Other comprehensive income (loss):
Unrealized gain on marketable securities, net of tax of $0	67	124
Comprehensive income (loss)	$ 22,637	$ (4,075)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Statement Of Income And Comprehensive Income [Abstract]
Marketable securities tax	$ 0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ 102,862	$ 3	$ 169,784	$ (119)	$ (66,806)
Beginning balance, share at Dec. 31, 2018		27,772,600
Issuance of common stock upon exercise of stock options	211		211
Issuance of common stock upon exercise of stock options, share		58,082
Stock-based compensation expense	1,395		1,395
Unrealized gain on marketable securities	124			124
Net income (loss)	(4,199)				(4,199)
Ending balance at Mar. 31, 2019	100,393	$ 3	171,390	5	(71,005)
Ending balance, share at Mar. 31, 2019		27,830,682
Beginning balance at Dec. 31, 2019	$ 56,666	$ 3	178,155	103	(121,595)
Beginning balance, share at Dec. 31, 2019	27,893,337	27,893,337
Issuance of common stock upon exercise of stock options	$ 10		10
Issuance of common stock upon exercise of stock options, share		27,832
Issuance of common stock under stock purchase plan	83		83
Issuance of common stock under stock purchase plan, share		49,025
Issuance of common stock upon public offering, net of issuance costs	320		320
Issuance of common stock upon public offering, net of issuance costs, shares		91,003
Stock-based compensation expense	1,850		1,850
Unrealized gain on marketable securities	67			67
Net income (loss)	22,570				22,570
Ending balance at Mar. 31, 2020	$ 81,566	$ 3	$ 180,418	$ 170	$ (99,025)
Ending balance, share at Mar. 31, 2020	28,061,197	28,061,197

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 22,570	$ (4,199)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization expense	457	430
Stock-based compensation expense	1,850	1,395
Non-cash interest expense related to note payable	176
Net amortization of premiums and discounts on marketable securities	(42)	(188)
Loss on disposal of property and equipment	1
Non-cash operating lease cost	587	291
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(444)	1,077
Other assets	(138)	(9)
Accounts payable	(2,651)	902
Accrued expenses and other current liabilities	(467)	(3,299)
Operating lease liability	17	(274)
Other liabilities	1,100
Deferred revenue - related party	(38,592)	(14,434)
Net cash used in operating activities	(15,576)	(18,308)
Cash flows from investing activities:
Purchases of property and equipment	(23)	(876)
Purchases of marketable investments	(650)	(70,301)
Proceeds from sales or maturities of marketable securities	25,500	47,675
Net cash provided by (used in) investing activities	24,827	(23,502)
Cash flows from financing activities:
Proceeds from issuance of common stock upon public offering, net	320
Proceeds from employee stock purchases	83
Proceeds from exercise of stock options	10	211
Net cash provided by financing activities	413	211
Net increase (decrease) in cash and cash equivalents and restricted cash	9,664	(41,599)
Cash and cash equivalents and restricted cash at beginning of period	48,350	84,110
Cash and cash equivalents and restricted cash at end of period	58,014	42,511
Supplemental disclosure of cash flow information:
Cash paid for interest	180
Supplemental disclosure of non-cash investing and financing activities:
Additional right-of-use asset and related lease liability	$ 15,003
Purchases of property and equipment included in accounts payable and accrued expenses		$ 137

Nature of the Business

Nature of the Business	3 Months Ended
	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business Surface Oncology, Inc. (the “Company” or “Surface”) is a clinical-stage immuno-oncology company focused on using its specialized knowledge of the biological pathways critical to the immunosuppressive tumor microenvironment (“TME”) for the development of next-generation cancer therapies. Surface was incorporated in April 2014 under the laws of the State of Delaware. The Company is subject to risks common to early-stage companies in the biotechnology industry including, but not limited to, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the ability to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. On May 1, 2019, the Company entered into a Capital on Demand TM The Company’s financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has primarily funded its operations with proceeds from the sales of redeemable convertible preferred stock, proceeds from a collaboration agreement with Novartis Institutes for Biomedical Research, Inc. (“Novartis”), issuance of a debt facility with K2 Health Ventures LLC and proceeds from the Company’s initial public offering of common stock. The Company has incurred losses and negative cash flows from operations since its inception. As of March 31, 2020, the Company had an accumulated deficit of $99,025. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. As of May 12, 2020, the issuance date of this Quarterly Report on Form 10-Q, the Company expects that its cash, cash equivalents and marketable securities of $90,084, will be sufficient to fund its operating expenses, debt service obligations and capital expenditure requirements for at least the next 12 months. The future viability of the Company beyond that date is dependent on its ability to raise additional capital to finance its operations. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be required to delay, reduce, or eliminate research and development programs, product portfolio expansion, or future commercialization efforts, which could adversely affect its business prospects. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. The ongoing global outbreak of the novel coronavirus disease (“COVID-19”) has resulted in significant governmental measures being implemented to control the spread of the virus and while we cannot predict their scope and severity, these developments and measures could materially and adversely affect our business, our results of operations and financial condition. We are closely monitoring the impact of the COVID-19 pandemic on all aspects of our business and have taken steps to minimize its impact on our business. However, the extent to which COVID-19 ultimately impacts our business, results of operations or financial condition will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the duration of the outbreak, new information that may emerge concerning the severity of COVID-19 or the effectiveness of actions taken to contain the pandemic or treat its impact, among others. Furthermore, for the safety of our employees, we have reduced the presence of our scientists in our labs and are relying on third parties to conduct many of the experiments and studies for our research programs. Certain of our third party service providers have also experienced shutdowns or other business disruptions. As a result, our ability to conduct our business in the manner and on the timelines presently planned could be materially or negatively affected, which could have a material adverse impact on our business, results of operations and financial condition.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiary, Surface Securities Corporation, a Massachusetts corporation, after elimination of all intercompany accounts and transactions. The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 2 to the financial statements included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 10, 2020. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. Changes in estimates are recorded in the period in which they become known. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including clinical trials, will depend on future developments that are highly uncertain, including new information that may emerge concerning COVID-19 and the actions taken to contain it or treat its impact and the economic impact. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Actual results could differ from the Company’s estimates. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2020, the condensed consolidated statements of operations and comprehensive income (loss) for the three months ended March 31, 2020 and 2019, the condensed consolidated statements of cash flows for the three months ended March 31, 2020 and 2019, and the condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2020 and 2019 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2020 and the results of its operations and its cash flows for the three months ended March 31, 2020 and 2019. The financial data and other information disclosed in these notes related to the three months ended March 31, 2020 and 2019 are also unaudited. The results for the three months ended March 31, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year period. Recently Adopted Accounting Pronouncements In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 This standard became effective for the Company on January 1, 2020 and the 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, (“ASU 2018-13”). This standard became effective for the Company on January 1, 2020, and did not have a material impact on the Company’s disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief This standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that this standard may have on its condensed consolidated financial statements and related disclosures. Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Marketable Securities

Marketable Securities	3 Months Ended
	Mar. 31, 2020
Marketable Securities [Abstract]
Marketable Securities	3. Marketable Securities As of March 31, 2020, the fair value of available-for-sale marketable debt securities by type of security was as follows: March 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable debt securities: U.S. Treasury notes $ 25,833 $ 132 $ — $ 25,965 U.S. Government agency bonds 7,662 38 — 7,700 $ 33,495 $ 170 $ — $ 33,665 The amortized cost and fair value of the Company’s available-for-sale debt securities by contractual maturity are summarized as follows: March 31, 2020 Amortized Cost Fair Value Maturing in one year or less $ 33,495 $ 33,665 $ 33,495 $ 33,665 As of December 31, 2019, the fair value of available-for-sale marketable debt securities by type of security was as follows: December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable debt securities: U.S. Treasury notes $ 42,795 $ 73 $ — $ 42,868 U.S. Government agency bonds 15,508 31 (1 ) $ 15,538 $ 58,303 $ 104 $ (1 ) $ 58,406 The amortized cost and fair value of the Company’s available-for-sale securities by contractual maturity are summarized as follows: December 31, 2019 Amortized Cost Fair Value Maturing in one year or less $ 58,303 $ 58,406 $ 58,303 $ 58,406 The Company determined that there was no material change in the credit risk of these investments. As a result, the Company determined it did not hold any investments with an other-than-temporary decline in fair value as of March 31, 2020 and December 31, 2019.

Fair Value of Financial Assets

Fair Value of Financial Assets	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets	4. Fair Value of Financial Assets The following tables present information about the Company’s financial assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of March 31, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 38,643 $ — $ — $ 38,643 Marketable securities: U.S. Treasury notes — 25,965 — 25,965 U.S. Government agency bonds — 7,700 — 7,700 $ 38,643 $ 33,665 $ — $ 72,308 Fair Value Measurements as of December 31, 2019 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 30,490 $ — $ — $ 30,490 U.S. Government agency bonds — 2,500 — 2,500 Marketable securities: U.S. Treasury notes — 42,868 — $ 42,868 U.S. Government agency bonds — 15,538 — 15,538 $ 30,490 $ 60,906 $ — $ 91,396 As of March 31, 2020 and December 31, 2019, the Company’s cash equivalents were invested in money market funds and were valued based on Level 1 inputs. During the three months ended March 31, 2020 and 2019, there were no transfers between Level 1, Level 2 and Level 3.

Collaboration Agreement with No

Collaboration Agreement with Novartis	3 Months Ended
	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Agreement with Novartis	5. Collaboration Agreement with Novartis Overview In January 2016, the Company entered into a collaboration agreement with Novartis (the “Collaboration Agreement”), which was subsequently amended in May 2016, July 2017, September 2017, and October 2018 (the “October 2018 Amendment”). Pursuant to the Collaboration Agreement, the Company granted Novartis a worldwide exclusive license to research, develop, manufacture and commercialize antibodies that target cluster of differentiation 73 (“CD73”). In addition, the Company initially granted Novartis the right to purchase exclusive option rights (each an “Option”) for up to four specified targets (each an “Option Target”) including certain development, manufacturing, and commercialization rights. Novartis initially had the right to exercise up to three purchased Options. Under the Collaboration Agreement, therefore, Novartis had the ability to exclusively license the development and manufacturing rights for up to four targets (inclusive of CD73). In January 2020, Novartis did not purchase and exercise its single remaining Option under the Collaboration Agreement and, as a result, the option purchase period expired. Therefore, there are no Options remaining eligible for purchase, and potential exercise, and the Company’s performance obligations under the Collaboration Agreement have ended. Novartis is a related party because it is a greater than 5% stockholder of the Company. In January 2016, the Company entered into the Collaboration Agreement and sold 2,000,000 shares of its Series A-1 redeemable convertible preferred stock (the “Series A-1 Preferred Stock”) to Novartis, which were subsequently converted to common stock. In addition, concurrent with the Company’s initial public offering of common stock, the Company issued Novartis 766,666 shares of its common stock at $15.00 per share for proceeds of $11,500 in a private placement. During the three months ended March 31, 2020 and 2019, the Company made no cash payments to Novartis related to the Collaboration Agreement. Development and Commercialization of CD73 Products Novartis has the sole right to develop and commercialize CD73 antibody candidates and corresponding licensed products worldwide pursuant to a development plan and a commercialization plan, respectively. Novartis is obligated to use commercially reasonable efforts to develop the CD73 antibody candidates and corresponding licensed products, obtain regulatory approval of such products, including within certain defined markets, and commercialize such products following regulatory approval. Novartis is responsible for all costs and expenses of such development and commercialization and is obligated to provide the Company with updates on its development and commercialization activities through a joint steering committee. Exclusivity Neither the Company nor Novartis may, alone or with any affiliate or third party, develop or commercialize any antibody that specifically binds to CD73. The October 2018 Amendment clarified that Novartis is permitted to research, develop, manufacture or commercialize any diagnostic product that specifically binds to CD73, subject to Novartis’ compliance with its rights and obligations under the Collaboration Agreement, and provided that where such diagnostic product is an Adimab diagnostic product, Novartis may research, develop, manufacture or commercialize such Adimab diagnostic product solely for the purpose of research, development or commercialization of a therapeutic or prophylactic licensed product that specifically binds to the same licensed target. Financial Terms Upon entering into the Collaboration Agreement in January 2016, Novartis made an upfront payment to the Company of $70,000. The Company is also eligible to receive payments upon the achievement of specified development and sales milestones as well as tiered royalties on annual net sales by Novartis ranging from high single-digit to mid-teens percentages, upon successful commercialization of NZV930. Under the Collaboration Agreement, the Company is currently entitled to potential milestones of $525,000, as well as tiered royalties on annual net sales by Novartis ranging from high single-digit to mid-teens percentages upon the successful commercialization of NZV930 (formerly SRF373). Termination Unless terminated earlier, the Collaboration Agreement will continue in effect until neither the Company nor Novartis is researching, developing, manufacturing, or commercializing NZV930. Novartis may terminate the Collaboration Agreement for any reason upon prior notice to the Company within a specified time period. Either party may terminate the Collaboration Agreement in full if an undisputed material breach is not cured within a certain period of time or upon notice of insolvency of the other party. To the extent Novartis terminates for convenience, or the Company terminates for Novartis’ material breach, Novartis will grant the Company, on mutually agreeable financial terms, an exclusive, worldwide, irrevocable, perpetual and royalty-bearing license with respect to intellectual property controlled by Novartis that is reasonably necessary to research, develop, manufacture or commercialize NZV930. Revenue Recognition – Collaboration Revenue – Related Party In determining the appropriate amount of revenue to be recognized under ASC 606, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. Under ASC 606, the Company recognized revenue using the cost-to-cost method, which it believes best depicts the transfer of control to the customer. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Under ASC 606, the estimated transaction price will include variable consideration. The Company does not include variable consideration to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will occur when any uncertainty associated with the variable consideration is resolved. The estimate of the Company’s measure of progress and estimate of variable consideration to be included in the transaction price will be updated at each reporting date as a change in estimate. The amount related to the unsatisfied portion will be recognized as that portion is satisfied over time. Under ASC 606 the Company accounts for (i) the license it conveyed with respect to CD73; and (ii) its obligations to perform research on CD73 and other specified targets as a single performance obligation under the collaboration agreement with Novartis. Novartis’ right to purchase exclusive options to obtain certain development, manufacturing and commercialization rights are accounted for separately as they do not represent material rights, based on the criteria of ASC 606. Upon the exercise of any purchased option by Novartis, the contract promises associated with an option target would use a separate cost-to-cost model for purposes of revenue recognition under ASC 606. In February 2019, Novartis notified the Company of its decision not to purchase the Option related to IL-27. Future costs associated with this target were removed from the estimated total costs in the cost-to-cost model. In January 2020, Novartis did not purchase and exercise its single remaining Option under the Collaboration Agreement and, as a result, the option purchase period expired. Future costs associated with this target were removed from the estimated total costs in the cost-to-cost model. This resulted in the Company recognizing the remaining deferred revenue of $ 38,592 For the three months ended March 31, 2020 and 2019, the Company recognized the following totals of collaboration revenue – related party: Three months ended March 31, 2020 2019 Collaboration revenue - related party $ 38,592 $ 14,434 The following table presents changes in the Company’s contract liabilities during the three months ended March 31, 2020: December 31, 2019 Additions Deductions March 31, 2020 Contract liabilities (1) Total deferred revenue - related party $ 38,592 $ — $ (38,592 ) $ — (1) Additions to contract liabilities relate to consideration from Novartis during the reporting period. Deductions to contract liabilities relate to deferred revenue recognized as revenue during the reporting period. During of revenue related to the amounts included in contract liability balance at the beginning of the period. there are no Options remaining eligible for purchase and exercise, the Company’s performance obligations under the Collaboration Agreement have ended.

Stockholders_ Equity

Stockholders’ Equity	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Stockholders’ Equity	6. Stockholders’ Equity Common Stock As of March 31, 2020 and December 31, 2019, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 150,000,000 shares, of $0.0001 par value common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any, subject to the preferential dividend rights of any outstanding preferred stock. No dividends have been declared or paid by the Company through March 31, 2020. As of March 31, 2020 and December 31, 2019, the Company had reserved 18,577,901 and 17,351,095 shares, respectively, of common stock for the exercise of outstanding stock options, shares to be issued under the ATM Facility, and the number of shares remaining available for future grant under the Company’s 2018 Stock Option and Incentive Plan, and 2018 Employee Stock Purchase Plan. In May 2019, the Company entered into the Sales Agreement with JonesTrading to issue and sell shares up to $30,000 in shares of the Company’s common stock from time to time. In the three months ended March 31, 2020, the Company sold 91,003 shares of common stock at-the-market under the Sales Agreement, resulting in net proceeds of approximately $320. Through March 31, 2020, the Company has sold 101,584 shares of common stock at-the-market under the Sales Agreement for net proceeds of $344.

Stock-Based Awards

Stock-Based Awards	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Awards	7. Stock-Based Awards 2014 Stock Incentive Plan The Company’s 2014 Stock Incentive Plan (the “2014 Plan”) provides for the Company to grant incentive stock options or nonqualified stock options, restricted stock awards, unrestricted stock awards or restricted stock units to employees, directors and consultants of the Company. The 2014 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or their committee if so delegated, except that the exercise price per share of the stock options may not be less than 100% of the fair market value of a share of the Company’s common stock on the date of grant and the term of the stock options may not be greater than ten years. As of December 31, 2018, all remaining shares available under the 2014 Plan were transferred to the Company’s 2018 Stock Option and Incentive Plan (the “2018 Plan”). 2018 Stock Option and Incentive Plan In April 2018, the Company’s 2018 Plan was approved by its stockholders and became effective. The 2018 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, non-employee directors and other key persons (including consultants). The number of shares initially reserved for issuance under the 2018 Plan was 1,545,454, plus the shares of common stock remaining available for issuance under the 2014 Plan, which shall be cumulatively increased each January 1 by 4% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s board of directors or compensation committee of the board of directors. The shares of common stock underlying any awards that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) under the 2018 Plan and the 2014 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan. As of March 31, 2020, 564,561 shares were available for future issuance under the 2018 Plan. Stock options granted under the 2014 Plan and 2018 Plan to employees generally vest over four years and expire after ten years. Stock Options The following table summarizes the Company’s stock option activity since January 1, 2020: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding as of December 31, 2019 5,418,113 $ 6.11 7.69 $ 690 Granted 1,143,800 3.16 Exercised (27,832 ) 0.35 Forfeited (241,209 ) 6.51 Outstanding as of March 31, 2020 6,292,872 $ 5.58 7.91 $ 643 Options exercisable at March 31, 2020 3,107,349 $ 5.61 6.98 $ 619 Vested and expected to vest at March 31, 2020 6,292,872 $ 5.58 7.91 $ 643 The weighted average grant-date fair value per share of stock options granted during the three months ended March 31, 2020 and year ended December 31, 2019 was $2.00 and $2.71, respectively. As of March 31, 2020 and December 31, 2019, there were outstanding stock options held by non-employees for the purchase of 267,372 and 272,343 shares of common stock, respectively, with service-based vesting conditions. 2018 Employee Stock Purchase Plan In April 2018, the Company’s 2018 Employee Stock Purchase Plan (the “ESPP”) was approved by its stockholders and became effective. A total of 256,818 shares of common stock were initially reserved for issuance under this plan. In addition, the number of shares of common stock that may be issued under the ESPP automatically increased on January 1, 2019, and shall increase each January 1 thereafter through January 1, 2028, by the lesser of (i) 1% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 and (ii) such lesser number of shares as determined by the administrator of the Company’s ESPP. As of March 31, 2020, a total of 764,452 shares of common stock were reserved for issuance under this plan. For the three months ended March 31, 2020, the Company issued 49,025 shares of common stock under the 2018 ESPP. For the three months ended March 31, 2019, the Company did not issue any shares of common stock under the 2018 ESPP. Restricted Stock Units The Company has granted restricted stock units (RSUs) with service-based vesting conditions. RSUs represent the right to receive shares of common stock upon meeting specified vesting requirements. Unvested shares of restricted common stock may not be sold or transferred by the holder. These restrictions lapse according to the service-based vesting conditions of each award. In February 2020, the Company granted 1,060,900 RSUs that vest in full on the eighteen-month anniversary as long as the individual remains an employee of the Company. The table below summarizes the Company’s restricted stock unit activity since December 31, 2019: Number of Shares Weighted Average Grant-Date Fair Value Unvested restricted stock units as of December 31, 2019 — $ — Granted 1,060,900 3.18 Vested — Forfeited (3,300 ) 3.18 Unvested restricted stock units as of March 31, 2020 1,057,600 $ 3.18 The expense related to RSUs granted to employees was $430 for the three months ended March 31, 2020. At March 31, 2020, there was $2,933 of total unrecognized compensation cost related to unvested restricted stock units, which is expected to be recognized over the remaining weighted-average vesting period of 1.31 years. Stock-Based Compensation The Company recorded stock-based compensation expense related to stock options and restricted stock unit awards in the following expense categories of its condensed consolidated statements of operations and comprehensive income (loss): Three months ended March 31, 2020 2019 Research and development expenses $ 682 $ 565 General and administrative expenses 1,168 830 $ 1,850 $ 1,395 As of March 31, 2020, the Company had an aggregate of $14,055 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 1.69 years.

Debt

Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt	8. Debt On November 22, 2019, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with K2 HealthVentures LLC (the “Lender”). The Lender has agreed to make available to the Company term loans in an aggregate principal amount of up to $25,000 under the Loan Agreement. The Company plans to use the proceeds of the term loans to support clinical development as well as for working capital and general corporate purposes. The Loan Agreement provides a term loan commitment of $25,000 in three potential tranches: (i) a $7,500 term loan facility funded on November 22, 2019 (the “First Tranche Term Loan”), (ii) a $10,000 term loan facility (the “Second Tranche Term Loan”), and (iii) a $7,500 term loan facility (the “Third Tranche Term Loan”). All three of these term loans have a maturity date of December 1, 2023. Borrowings under all three loan facilities bear interest at a floating per annum rate equal to the greater of (i) 8.65% and (ii) the Prime Rate plus 3.90%. The Company is permitted to make interest-only payments on the First Tranche Term Loan for the first nineteen months following the funding date. The interest-only period can be extended by an additional seven months, subject to the funding of the Second Tranche Term Loan; and by an additional seven months, subject to the funding of the Third Tranche Term Loan. The term of the combined facility will be 48 months, with repayment in monthly installments commencing at the end of the resulting interest-only period as outlined above through the end of the 48-month term. The Company is obligated to pay a final fee equal to 4.45% of the aggregate amount of the term loans funded, such payment to occur upon the earliest of (i) the maturity date, (ii) the acceleration of the term loans, and (iii) the prepayment of the term loans. The Company has the option to prepay all, but not less than all, of the outstanding principal balance of the term loans under the Loan Agreement. If the Company prepays all of the term loans prior to the maturity date, it will pay the Lender a prepayment penalty fee based on a percentage of the outstanding principal balance, equal to 5% if the payment occurs on or before 24 months after the initial funding date, 3% if the prepayment occurs more than 24 months after, but on or before 36 months after the initial funding date, or 1% if the prepayment occurs more than 36 months after the initial funding date. The Lender may, at its option, elect to convert any portion of no more than $4,000 of the then outstanding term loan amount and all accrued and unpaid interest thereon into shares of the Company’s common stock at a conversion price of $1.56 per share. The Company determined that the embedded conversion option is not required to be separated from the term loan. The embedded conversion option meets the derivative accounting scope exception since the embedded conversion option is indexed to the Company’s own common stock and qualifies for classification within stockholders’ equity. The Company did recognize a beneficial conversion feature of $2,101, which represents the difference between the commitment date stock price of $2.33 per share and the conversion price of $1.56 per share. The beneficial conversion feature was recorded as a discount on the term loan and is accreted to interest expense using the effective interest method over the term of the loan. The effective interest rate of the term loan is 27.84%. The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of its assets. The Loan Agreement contains customary representations, warranties and also includes customary events of default, including payment defaults, breaches of covenants, change of control and a material adverse effect clause. Upon the occurrence of an event of default, a default interest rate of an additional 5.00% per annum may be applied to the outstanding loan balances, and the Lender may declare all outstanding obligations immediately due and payable and exercise all of its rights and remedies as set forth in the Loan Agreement and under applicable law. The Company recorded interest expense related to the loan facility of $340 for the three months ended March 31, 2020. The fair value of the loan at March 31, 2020 approximates its face amount due to the floating interest rate. Future principal debt payments on the loan payable are as follows: March 31, 2020 2020 $ - 2021 1,602 2022 2,947 2023 2,951 Total principal payments 7,500 Final fee due at maturity in 2024 334 Total principal payments and final fee 7,834 Unamortized debt discount and final fee 2,549 Note payable $ 5,285

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share	9. Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three months ended March 31, 2020 2019 Basic net income (loss) per share attributable to common stockholders: Numerator: Net income (loss) $ 22,570 $ (4,199 ) Denominator: Weighted average commons shares outstanding — basic 27,977,145 27,825,698 Net income (loss) per share attributable to common stockholders — basic $ 0.81 $ (0.15 ) Diluted net income (loss) per share attributable to common stockholders: Numerator: Net income (loss) attributable to common shareholders - basic $ 22,570 $ (4,199 ) Interest expense on convertible note payable 181 — Net income (loss) attributable to common shareholders - diluted $ 22,751 $ (4,199 ) Denominator: Weighted average commons shares outstanding — basic 27,977,145 27,825,698 Shares issuable upon conversion of convertible notes, as if converted 2,564,102 — Dilutive effect of common stock equivalents 376,205 — Weighted average common shares outstanding - diluted 30,917,452 27,825,698 Net income (loss) per share attributable to common stockholders — diluted 0.74 (0.15 ) Stock options and restricted stock units for the purchase of 5,555,623 and 675,162, weighted average shares were excluded from the computation of diluted net income per share attributable to common stockholders for the three months ended March 31, 2020 because those options and restricted stock units had an anti-dilutive impact due to the assumed proceeds per share using the treasury stock method being greater than the average fair value of the Company’s common shares for those periods.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes The Company did not provide for any income taxes for the three months ended March 31, 2020 or 2019. The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the deferred tax assets as of March 31, 2020 and December 31, 2019. Management reevaluates the positive and negative evidence at each reporting period. As of March 31, 2020 and December 31, 2019, the Company had no accrued interest or tax penalties recorded. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. The Company is currently under examination by the Internal Revenue Service ("IRS") for the period ended December 31, 2016. The Company's tax years are still open under statute from 2015 to present. All years may be examined to the extent the tax credit or net operating loss carryforwards are used in future periods.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	11. Leases The Company leases real estate, primarily its corporate headquarters in Cambridge, Massachusetts. The Company’s leases have remaining terms ranging from less than 1 year to 10 years. Certain leases include options to renew, exercised at the Company’s sole discretion, with renewal terms that can extend the lease five years. The Company evaluated the renewal options in its leases to determine if it was reasonably certain that the renewal option would be exercised, and therefore should be included in the calculation of the operating lease assets and operating lease liabilities. Given the Company’s current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that the renewal option related to its corporate headquarters would be exercised. However, for leases it determined the renewal option was probable to be exercised, the Company included the renewal period in the calculation of the operating lease right-of-use With the adoption of the new leasing standard, the Company has recorded a right-of-use asset and corresponding lease liability, by calculating the present value of future lease payments, discounted at either 9.5% or 10.5%, the Company’s incremental borrowing rates, over the expected term. The right-of-use asset is reduced by any lease incentives received and the legacy deferred rent balance. In May 2016, the Company entered into an operating lease agreement for its corporate headquarters in Cambridge, Massachusetts, with a ten-year term that expires in February 2027 (“Initial Space”). Rental payments related to the lease commenced in April 2017. In connection with this lease, the Company was entitled to cash incentives from the landlord to be used for the construction of leasehold improvements within the facility. As of January 1, 2019, the Company was entitled to $4,803 of such incentives, which were recorded as a reduction to the right-of-use asset and included as a straight-line reduction to lease expense over the lease term. In May 2018, the Company executed an amendment to lease an additional 33,526 square feet at 50 Hampshire Street in Cambridge, Massachusetts, with a 10-year term (“Expansion Space”). This additional space became available for occupancy on January 1, 2020 and rental payments related to the lease commenced in April 2020. In connection with this lease amendment, the Company is entitled to a landlord-provided tenant improvement allowance of up to $1,005 to be applied to the cost of the construction of leasehold improvements. The Company determined that it owns the leasehold improvements and, as such, reflected the $1,005 lease incentive as a reduction of the rental payments used to measure the operating lease liability, and, in turn, the operating lease right of use asset as of the lease commencement date. The components of the Company’s lease expense are as follows: Lease Costs Classification Three months ended March 31, 2020 Three months ended March 31, 2019 Operating lease cost R&D Expense 540 586 G&A Expense 798 224 Variable lease costs (1) R&D Expense 198 172 G&A Expense 299 66 Total lease cost 1,835 1,048 Weighted-average remaining lease term (in months) 118.3 127.6 Weighted-average discount rate 10.5 % 10.4 % (1) Variable lease costs include certain additional charges for operating costs, including insurance, maintenance, taxes, utilities, and other costs incurred, which are billed based on both usage and as a percentage of the Company’s share of total square footage. Short term lease costs are immaterial. Cash paid for amounts included in the measurement of the Company’s operating lease liabilities was $1,412 for the three months ended March 31, 2020. As of March 31, 2020, the maturities of the Company’s operating lease liabilities were as follows: Year Ending December 31, 2020 3,061 2021 5,529 2022 5,385 2023 5,413 2024 5,533 Thereafter 31,521 Total future lease payments 56,442 Less: Interest (21,456 ) Present value of future lease payments (lease liability) $ 34,986 Future minimum lease payments for the Company’s operating leases as of December 31, 2019 were as follows: Year Ending December 31, 2020 4,802 2021 5,529 2022 5,385 2023 5,413 2024 5,533 Thereafter 31,827 $ 58,489 Sublease Agreement with EQRx, Inc. In December 2019, the Company entered into a sublease agreement with EQRx, Inc. to sublease the entire Expansion Space. The term of the sublease agreement commenced in January 2020 and ends on the last day of the 36th calendar month following commencement, with no option to extend. The annual rent for the subleased premises is greater than the annual rent owed by the Company to the landlord for the leased premises. The sublessee is obligated to pay all real estate taxes and costs related to the subleased premises, including cost of operations, maintenance, repair, replacement and property management. The Company concluded that the sublease is an operating lease. Consistent with the Company’s policy election for lessor operating leases, each lease component and its associated non-lease components is accounted for as a single lease component. As of March 31, 2020, future undiscounted cash inflows under the sublease are as follows: Year Ending December 31, 2020 1,896 2021 2,579 2022 2,635 2023 220 $ 7,330

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies Legal Proceedings The Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to its legal proceedings.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	13. Related Party Transactions Novartis Institutes for BioMedical Research, Inc. Novartis is a related party because it is a greater than 5% stockholder of the Company. In January 2016, the Company entered into the Collaboration Agreement and sold 2,000,000 shares of its Series A-1 Preferred Stock to Novartis for gross proceeds of $13,500. In addition, concurrent with the Company’s initial public offering of common stock, the Company issued Novartis 766,666 shares of its common stock at $15.00 per share, for proceeds of $11,500 in a private placement. During the three months ended March 31, 2020, the Company recognized $38,592 of collaboration revenue under the Collaboration Agreement. As of March 31, 2020 and 2019, no amounts were due from Novartis. During the three months ended March 31, 2020 and 2019, the Company made no cash payments to Novartis related to the Collaboration Agreement. Research Agreement with Vaccinex, Inc. On November 30, 2017, the Company entered into an agreement with Vaccinex, Inc. (“Vaccinex”) whereby Vaccinex will use its technology to assist the Company with identifying and selecting experimental human monoclonal antibodies against targets selected by the Company. The Company’s Chief Executive Officer is a member of the board of directors of Vaccinex. During the three months ended March 31, 2020, the Company made no payments relating to the agreement. During the three months ended March 31, 2019, the Company paid Vaccinex an aggregate of $83 relating to the agreement. The payments were recognized as research and development expense. There was no amount due by the Company to Vaccinex as of March 31, 2020 and 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiary, Surface Securities Corporation, a Massachusetts corporation, after elimination of all intercompany accounts and transactions. The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 2 to the financial statements included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 10, 2020.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. Changes in estimates are recorded in the period in which they become known. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including clinical trials, will depend on future developments that are highly uncertain, including new information that may emerge concerning COVID-19 and the actions taken to contain it or treat its impact and the economic impact. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Actual results could differ from the Company’s estimates.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2020, the condensed consolidated statements of operations and comprehensive income (loss) for the three months ended March 31, 2020 and 2019, the condensed consolidated statements of cash flows for the three months ended March 31, 2020 and 2019, and the condensed consolidated statement of stockholders’ equity for the three months ended March 31, 2020 and 2019 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2020 and the results of its operations and its cash flows for the three months ended March 31, 2020 and 2019. The financial data and other information disclosed in these notes related to the three months ended March 31, 2020 and 2019 are also unaudited. The results for the three months ended March 31, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year period.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 This standard became effective for the Company on January 1, 2020 and the 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, (“ASU 2018-13”). This standard became effective for the Company on January 1, 2020, and did not have a material impact on the Company’s disclosures.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief This standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that this standard may have on its condensed consolidated financial statements and related disclosures. Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Marketable Securities (Tables)

Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2020
Marketable Securities [Abstract]
Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security	As of March 31, 2020, the fair value of available-for-sale marketable debt securities by type of security was as follows: March 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable debt securities: U.S. Treasury notes $ 25,833 $ 132 $ — $ 25,965 U.S. Government agency bonds 7,662 38 — 7,700 $ 33,495 $ 170 $ — $ 33,665 As of December 31, 2019, the fair value of available-for-sale marketable debt securities by type of security was as follows: December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Marketable debt securities: U.S. Treasury notes $ 42,795 $ 73 $ — $ 42,868 U.S. Government agency bonds 15,508 31 (1 ) $ 15,538 $ 58,303 $ 104 $ (1 ) $ 58,406
Summary of Available-for-sale Debt Securities by Contractual Maturity	The amortized cost and fair value of the Company’s available-for-sale debt securities by contractual maturity are summarized as follows: March 31, 2020 Amortized Cost Fair Value Maturing in one year or less $ 33,495 $ 33,665 $ 33,495 $ 33,665 The amortized cost and fair value of the Company’s available-for-sale securities by contractual maturity are summarized as follows: December 31, 2019 Amortized Cost Fair Value Maturing in one year or less $ 58,303 $ 58,406 $ 58,303 $ 58,406

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s financial assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of March 31, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 38,643 $ — $ — $ 38,643 Marketable securities: U.S. Treasury notes — 25,965 — 25,965 U.S. Government agency bonds — 7,700 — 7,700 $ 38,643 $ 33,665 $ — $ 72,308 Fair Value Measurements as of December 31, 2019 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 30,490 $ — $ — $ 30,490 U.S. Government agency bonds — 2,500 — 2,500 Marketable securities: U.S. Treasury notes — 42,868 — $ 42,868 U.S. Government agency bonds — 15,538 — 15,538 $ 30,490 $ 60,906 $ — $ 91,396

Collaboration Agreement with _2

Collaboration Agreement with Novartis (Tables)	3 Months Ended
	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Collaboration Revenue Related Party	For the three months ended March 31, 2020 and 2019, the Company recognized the following totals of collaboration revenue – related party: Three months ended March 31, 2020 2019 Collaboration revenue - related party $ 38,592 $ 14,434
Summary of Changes in Contract Liabilities	The following table presents changes in the Company’s contract liabilities during the three months ended March 31, 2020: December 31, 2019 Additions Deductions March 31, 2020 Contract liabilities (1) Total deferred revenue - related party $ 38,592 $ — $ (38,592 ) $ — (1) Additions to contract liabilities relate to consideration from Novartis during the reporting period. Deductions to contract liabilities relate to deferred revenue recognized as revenue during the reporting period.

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity since January 1, 2020: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) Outstanding as of December 31, 2019 5,418,113 $ 6.11 7.69 $ 690 Granted 1,143,800 3.16 Exercised (27,832 ) 0.35 Forfeited (241,209 ) 6.51 Outstanding as of March 31, 2020 6,292,872 $ 5.58 7.91 $ 643 Options exercisable at March 31, 2020 3,107,349 $ 5.61 6.98 $ 619 Vested and expected to vest at March 31, 2020 6,292,872 $ 5.58 7.91 $ 643
Summary of Restricted Stock Unit Activity	The table below summarizes the Company’s restricted stock unit activity since December 31, 2019: Number of Shares Weighted Average Grant-Date Fair Value Unvested restricted stock units as of December 31, 2019 — $ — Granted 1,060,900 3.18 Vested — Forfeited (3,300 ) 3.18 Unvested restricted stock units as of March 31, 2020 1,057,600 $ 3.18
Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Stock Awards	The Company recorded stock-based compensation expense related to stock options and restricted stock unit awards in the following expense categories of its condensed consolidated statements of operations and comprehensive income (loss): Three months ended March 31, 2020 2019 Research and development expenses $ 682 $ 565 General and administrative expenses 1,168 830 $ 1,850 $ 1,395

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule of Future Principal Debt Payments on the Loan Payable	Future principal debt payments on the loan payable are as follows: March 31, 2020 2020 $ - 2021 1,602 2022 2,947 2023 2,951 Total principal payments 7,500 Final fee due at maturity in 2024 334 Total principal payments and final fee 7,834 Unamortized debt discount and final fee 2,549 Note payable $ 5,285

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three months ended March 31, 2020 2019 Basic net income (loss) per share attributable to common stockholders: Numerator: Net income (loss) $ 22,570 $ (4,199 ) Denominator: Weighted average commons shares outstanding — basic 27,977,145 27,825,698 Net income (loss) per share attributable to common stockholders — basic $ 0.81 $ (0.15 ) Diluted net income (loss) per share attributable to common stockholders: Numerator: Net income (loss) attributable to common shareholders - basic $ 22,570 $ (4,199 ) Interest expense on convertible note payable 181 — Net income (loss) attributable to common shareholders - diluted $ 22,751 $ (4,199 ) Denominator: Weighted average commons shares outstanding — basic 27,977,145 27,825,698 Shares issuable upon conversion of convertible notes, as if converted 2,564,102 — Dilutive effect of common stock equivalents 376,205 — Weighted average common shares outstanding - diluted 30,917,452 27,825,698 Net income (loss) per share attributable to common stockholders — diluted 0.74 (0.15 )

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Summary of Components of Lease Expense	The components of the Company’s lease expense are as follows: Lease Costs Classification Three months ended March 31, 2020 Three months ended March 31, 2019 Operating lease cost R&D Expense 540 586 G&A Expense 798 224 Variable lease costs (1) R&D Expense 198 172 G&A Expense 299 66 Total lease cost 1,835 1,048 Weighted-average remaining lease term (in months) 118.3 127.6 Weighted-average discount rate 10.5 % 10.4 % (1) Variable lease costs include certain additional charges for operating costs, including insurance, maintenance, taxes, utilities, and other costs incurred, which are billed based on both usage and as a percentage of the Company’s share of total square footage. Short term lease costs are immaterial.
Schedule of Maturities of Operating Lease Liabilities	As of March 31, 2020, the maturities of the Company’s operating lease liabilities were as follows: Year Ending December 31, 2020 3,061 2021 5,529 2022 5,385 2023 5,413 2024 5,533 Thereafter 31,521 Total future lease payments 56,442 Less: Interest (21,456 ) Present value of future lease payments (lease liability) $ 34,986 Future minimum lease payments for the Company’s operating leases as of December 31, 2019 were as follows: Year Ending December 31, 2020 4,802 2021 5,529 2022 5,385 2023 5,413 2024 5,533 Thereafter 31,827 $ 58,489
Schedule of Future Undiscounted Cash Inflows Under Sublease	As of March 31, 2020, future undiscounted cash inflows under the sublease are as follows: Year Ending December 31, 2020 1,896 2021 2,579 2022 2,635 2023 220 $ 7,330

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) - USD ($)	May 01, 2019	May 31, 2019	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
State of incorporation			DE
Accumulated deficit			$ 99,025,000	$ 99,025,000	$ 121,595,000
Operating expenses and capital expenditure requirements			12 months
Cash, cash equivalents and marketable securities			$ 90,084,000	$ 90,084,000
ATM Facility
Class Of Stock [Line Items]
Common stock, issued			91,003	101,584
Net proceeds from issuance of common stock			$ 320,000	$ 344,000
ATM Facility | Maximum
Class Of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 30,000,000	$ 30,000,000
Percentage of gross proceeds of shares sold for compensation	3.00%

Marketable Securities - Summary

Marketable Securities - Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 33,495	$ 58,303
Gross Unrealized Gains	170	104
Gross Unrealized Losses		(1)
Fair Value	33,665	58,406
U.S. Treasury Notes
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	25,833	42,795
Gross Unrealized Gains	132	73
Fair Value	25,965	42,868
U.S. Government Agency Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	7,662	15,508
Gross Unrealized Gains	38	31
Gross Unrealized Losses		(1)
Fair Value	$ 7,700	$ 15,538

Marketable Securities - Summa_2

Marketable Securities - Summary of Fair Value of Available-for-sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available For Sale Securities [Abstract]
Maturing in one year or less, Amortized Cost	$ 33,495	$ 58,303
Amortized Cost	33,495	58,303
Maturing in one year or less, Fair Value	33,665	58,406
Fair Value	$ 33,665	$ 58,406

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Available For Sale Securities [Abstract]
Investments in other-than-temporary decline in fair value	$ 0	$ 0

Fair Value of Financial Assets

Fair Value of Financial Assets - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	$ 72,308	$ 91,396
Cash Equivalents | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	38,643	30,490
Cash Equivalents | U.S. Government Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis		2,500
Marketable Securities | U.S. Treasury Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	25,965	42,868
Marketable Securities | U.S. Government Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	7,700	15,538
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	38,643	30,490
Level 1 | Cash Equivalents | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	38,643	30,490
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	33,665	60,906
Level 2 | Cash Equivalents | U.S. Government Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis		2,500
Level 2 | Marketable Securities | U.S. Treasury Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	25,965	42,868
Level 2 | Marketable Securities | U.S. Government Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured on recurring basis	$ 7,700	$ 15,538

Fair Value of Financial Asset_2

Fair Value of Financial Assets - Additional Information (Details) - USD ($)	Mar. 31, 2020	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair value assets transfers between level 1 to level 2	$ 0	$ 0
Fair value assets transfers between level 2 to level 1	0	0
Fair value assets transfers between level 1 to level 3	0	0
Fair value assets transfers between level 3 to level 1	0	0
Fair value assets transfers between level 2 to level 3	0	0
Fair value assets transfers between level 3 to level 2	$ 0	$ 0

Collaboration Agreement with _3

Collaboration Agreement with Novartis - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended
	Jan. 31, 2020	Jan. 31, 2016	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Preferred stock shares issued to related party			0		0
Collaboration revenue - related party			$ 38,592,000	$ 14,434,000
Type of Revenue [Extensible List]			us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember
Novartis
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for reimbursement of manufacturing costs incurred			$ 0	$ 0
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for reimbursement of manufacturing costs incurred			0	$ 0
Collaboration revenue - related party	$ 38,592,000		38,592,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Up Front Payment Arrangement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from collaboration arrangement		$ 70,000,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Milestone Payment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestones payment			$ 525,000,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of share holding		5.00%
Novartis Collaboration | Series A One Redeemable Convertible Preferred Stock | Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Preferred stock shares issued to related party		2,000,000
Novartis Collaboration | Private Placement | Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock shares issued to related party		766,666
Share price		$ 15
Proceeds from stock issued to related party in private placement		$ 11,500,000

Collaboration Agreement with _4

Collaboration Agreement with Novartis - Schedule of Collaboration Revenue Related Party (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue - related party	$ 38,592	$ 14,434
ASU 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue - related party		$ 14,434

Collaboration Agreement with _5

Collaboration Agreement with Novartis - Summary of Changes in Contract Liabilities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Change In Contract With Customer Asset And Liability [Abstract]
Deferred revenue - Beginning balance	$ 38,592
Deferred revenue - Deductions	$ (38,592)

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	May 01, 2019USD ($)	May 31, 2019USD ($)	Mar. 31, 2020USD ($)Vote$ / sharesshares	Mar. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019$ / sharesshares
Subsidiary Sale Of Stock [Line Items]
Common stock, authorized | shares			150,000,000	150,000,000	150,000,000
Common stock, par value | $ / shares			$ 0.0001	$ 0.0001	$ 0.0001
Number of votes entitled by each share of common stock holder | Vote			1
Common stock voting rights			Each share of common stock entitles the holder to one vote
Dividends, declared or paid | $			$ 0
Total reserved | shares			18,577,901	18,577,901	17,351,095
ATM Facility
Subsidiary Sale Of Stock [Line Items]
Common stock, issued | shares			91,003	101,584
Net proceeds from issuance of common stock | $			$ 320,000	$ 344,000
Maximum | ATM Facility
Subsidiary Sale Of Stock [Line Items]
Gross proceeds from issuance of common stock | $	$ 30,000,000	$ 30,000,000

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 03, 2018	Feb. 29, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense			$ 1,850	$ 1,395
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost, weighted-average period			1 year 8 months 8 days
Unrecognized stock-based compensation cost			$ 14,055
Employee Stock Option | Non-Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock converted under option plan			267,372		272,343
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted vesting period		18 months
Number of shares granted		1,060,900	1,057,600
Unrecognized stock-based compensation cost			$ 2,933
Unrecognized stock-based compensation cost, weighted-average period			1 year 3 months 21 days
Restricted Stock Units | Granted to Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense			$ 430
2014 Plan | Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price per share of stock options to fair market value of share of common stock			100.00%
Stock options granted expiry period			10 years
Weighted average grant-date fair value per share of stock options granted			$ 2		$ 2.71
2018 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock to be issued	1,545,454
Percentage of authorized number of shares of common stock outstanding	4.00%
Number of shares of common stock converted under option plan			6,292,872		5,418,113
2018 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares available for further issuance			564,561
2018 Stock Option and Incentive Plan | 2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock to be issued	256,818		764,452
Percentage of authorized number of shares of common stock outstanding	1.00%
Number of shares of common stock issued			49,025	0
2014 Plan and 2018 Plan | Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted expiry period			10 years
Stock options granted vesting period			4 years

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Activity (Details) - 2018 Stock Option and Incentive Plan - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding beginning balance	5,418,113
Number of Shares, Granted	1,143,800
Number of Shares, Exercised	(27,832)
Number of Shares, Forfeited	(241,209)
Number of Shares, Outstanding ending balance	6,292,872	5,418,113
Number of Shares, Options exercisable at March 31, 2020	3,107,349
Number of Shares, Vested and expected to vest at March 31, 2020	6,292,872
Weighted Average Exercise Price, Outstanding beginning balance	$ 6.11
Weighted Average Exercise Price, Granted	3.16
Weighted Average Exercise Price, Exercised	0.35
Weighted Average Exercise Price, Forfeited	6.51
Weighted Average Exercise Price, Outstanding ending balance	5.58	$ 6.11
Weighted Average Exercise Price, Options exercisable at Marc 31, 2020	5.61
Weighted Average Exercise Price, Vested and expected to vest at Marc 31, 2020	$ 5.58
Weighted Average Remaining Contractual Term (in years), Outstanding	7 years 10 months 28 days	7 years 8 months 8 days
Weighted Average Remaining Contractual Term (in years), Options exercisable	6 years 11 months 23 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest	7 years 10 months 28 days
Aggregate Intrinsic Value	$ 643	$ 690
Aggregate Intrinsic Value, Options exercisable at March 31, 2020	619
Aggregate Intrinsic Value, Vested and expected to vest at March 31, 2020	$ 643

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2020$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested restricted stock units, Granted | shares	1,060,900
Unvested restricted stock units, Forfeited | shares	(3,300)
Unvested restricted stock units, ending balance | shares	1,057,600
Weighted Average Grant-Date Fair Value, Granted | $ / shares	$ 3.18
Weighted Average Grant-Date Fair Value, Forfeited | $ / shares	3.18
Weighted Average Grant-Date Fair Value, ending balance | $ / shares	$ 3.18

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Stock Awards (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	$ 1,850	$ 1,395
Research and Development Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	682	565
General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,168	$ 830

Debt - Additional Information (

Debt - Additional Information (Details) - Loan and Security Agreement - K2 Health Ventures LLC	Nov. 22, 2019USD ($)Tranche$ / shares	Mar. 31, 2020USD ($)
Debt Instrument [Line Items]
Commitment date stock price | $ / shares	$ 2.33
Effective interest rate	27.84
Term Loans
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000,000
Number of potential tranches | Tranche	3
Line of credit facility, expiration date	Dec. 1, 2023
Debt instrument interest rate, floating	8.65%
Term of the combined facility	48 months
Final fee percentage	4.45%
Conversion price per share | $ / shares	$ 1.56
Beneficial conversion feature	$ 2,101,000
Default interest rate	5.00%
Interest expense		$ 340,000
Term Loans | Maximum
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 4,000,000
Term Loans | Payment Occurs on or before Twenty Four Months after Initial Funding Date [Member]
Debt Instrument [Line Items]
Prepayment penalty fee percentage	5.00%
Term Loans | Prepayment Occurs More than Twenty Four Months after, but on or before Thirty Six Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	3.00%
Term Loans | Prepayment Occurs More than Thirty Six Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	1.00%
Term Loans | Prime Rate
Debt Instrument [Line Items]
Debt instrument variable rate	3.90%
First Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 7,500,000
Line of credit facility, initiation date	Nov. 22, 2019
Debt instrument interest only payment period	19 months
Debt instrument interest only payment extension period subject to funding of second tranche term loan	7 months
Debt instrument interest only payment extension period subject to funding of third tranche term loan	7 months
Second Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10,000,000
Third Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 7,500,000

Debt - Schedule of Future Princ

Debt - Schedule of Future Principal Debt Payments on the Loan Payable (Details) - Notes Payable $ in Thousands	Mar. 31, 2020USD ($)
Debt Instrument [Line Items]
2021	$ 1,602
2022	2,947
2023	2,951
Total principal payments	7,500
Final fee due at maturity in 2024	334
Total principal payments and final fee	7,834
Unamortized debt discount and final fee	2,549
Note payable	$ 5,285

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ 22,570	$ (4,199)
Denominator:
Weighted average commons shares outstanding — basic	27,977,145	27,825,698
Net income (loss) per share attributable to common stockholders— basic	$ 0.81	$ (0.15)
Numerator:
Net income (loss) attributable to common shareholders - basic	$ 22,570	$ (4,199)
Interest expense on convertible note payable	181
Net income (loss) attributable to common shareholders - diluted	$ 22,751	$ (4,199)
Denominator:
Weighted average commons shares outstanding — basic	27,977,145	27,825,698
Shares issuable upon conversion of convertible notes, as if converted	2,564,102
Dilutive effect of common stock equivalents	376,205
Weighted average common shares outstanding - diluted	30,917,452	27,825,698
Net income (loss) per share attributable to common stockholders — diluted	$ 0.74	$ (0.15)

Net Loss per Share - Additional

Net Loss per Share - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020shares
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders	5,555,623
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders	675,162

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Income tax provision or benefit	$ 0	$ 0
Interest and penalties accrued	$ 0		$ 0
Income tax examination, description	The Company is currently under examination by the Internal Revenue Service ("IRS") for the period ended December 31, 2016. The Company's tax years are still open under statute from 2015 to present. All years may be examined to the extent the tax credit or net operating loss carryforwards are used in future periods
Earliest Tax Year
Operating Loss Carryforwards [Line Items]
Tax year remain open	2015
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Income tax examination, year under examination	2016

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	Apr. 30, 2020USD ($)	May 31, 2018ft²	Mar. 31, 2020USD ($)
Lease Agreements [Line Items]
Cash paid for lease liabilities			$ 1,412
MASSACHUSETTS
Lease Agreements [Line Items]
Lease term			10 years
Renewal terms of lease			5 years
Renewal terms of lease			2027-02
Lease commenced period			2017-04
Operating lease, incentives			$ 4,803
MASSACHUSETTS | Sublease Agreement with EQRx
Lease Agreements [Line Items]
Term of contract			The term of the sublease agreement commenced in January 2020 and ends on the last day of the 36th calendar month following commencement, with no option to extend.
MASSACHUSETTS | Office Space | Sublease Agreement with EQRx
Lease Agreements [Line Items]
Option to extend			no
MASSACHUSETTS | Lease Amendment
Lease Agreements [Line Items]
Lease term		10 years
Lease term, description		In May 2018, the Company executed an amendment to lease an additional 33,526 square feet at 50 Hampshire Street in Cambridge, Massachusetts, with a 10-year term (“Expansion Space”). This additional space became available for occupancy on January 1, 2020 and rental payments related to the lease commenced in April 2020
Land subject to additional ground leases | ft²		33,526
MASSACHUSETTS | Lease Amendment | Office Space | Subsequent Event
Lease Agreements [Line Items]
Tenant improvement allowance	$ 1,005
Lease incentive as reduction of rental payments	$ 1,005
MASSACHUSETTS | Minimum
Lease Agreements [Line Items]
Lease term			1 year
Operating lease, discount rate			9.50%
MASSACHUSETTS | Maximum
Lease Agreements [Line Items]
Lease term			10 years
Operating lease, discount rate			10.50%

Leases - Summary of Components

Leases - Summary of Components of Lease Expense (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Lease Agreements [Line Items]
Operating lease cost		$ 587	$ 291
Total lease cost		$ 1,835	$ 1,048
Weighted-average remaining lease term (in months)		118 months 9 days	127 months 18 days
Weighted-average discount rate		10.50%	10.40%
Research and Development Expenses
Lease Agreements [Line Items]
Operating lease cost		$ 540	$ 586
Variable lease costs	[1]	198	172
General and Administrative Expenses
Lease Agreements [Line Items]
Operating lease cost		798	224
Variable lease costs		$ 299	$ 66
[1]	Variable lease costs include certain additional charges for operating costs, including insurance, maintenance, taxes, utilities, and other costs incurred, which are billed based on both usage and as a percentage of the Company’s share of total square footage. Short term lease costs are immaterial.

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2020	$ 3,061	$ 4,802
2021	5,529	5,529
2022	5,385	5,385
2023	5,413	5,413
2024	5,533	5,533
Thereafter	31,521	31,827
Total future lease payments	56,442	$ 58,489
Less: Interest	(21,456)
Present value of future lease payments (lease liability)	$ 34,986

Leases - Schedule of Future Und

Leases - Schedule of Future Undiscounted Cash Inflows Under Sublease (Details) - Sublease Agreement with EQRx $ in Thousands	Mar. 31, 2020USD ($)
Lease Agreements [Line Items]
2020	$ 1,896
2021	2,579
2022	2,635
2023	220
Total future sublease payments	$ 7,330

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended
	Jan. 31, 2020	Jan. 31, 2016	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Preferred stock shares issued to related party			0		0
Collaboration revenue			$ 38,592,000	$ 14,434,000
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration
Related Party Transaction [Line Items]
Collaboration revenue	$ 38,592,000		38,592,000
Amounts due from related party			0	0
Payment for reimbursement of manufacturing costs incurred			0	0
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Minimum
Related Party Transaction [Line Items]
Percentage of share holding		5.00%
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Series A One Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Preferred stock shares issued to related party		2,000,000
Gross proceeds from issuance of preference stock		$ 13,500,000
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Private Placement
Related Party Transaction [Line Items]
Common stock shares issued to related party		766,666
Share price		$ 15
Proceeds from private placement		$ 11,500,000
Vaccinex, Inc.
Related Party Transaction [Line Items]
Due to related party			0	0
Vaccinex, Inc. | Research and Development Expenses
Related Party Transaction [Line Items]
Payments to related party			$ 0	$ 83,000