0001718108-20-000015 | 10-Q | XBRL Viewer

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Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2020	Nov. 05, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-38459
Entity Registrant Name	SURFACE ONCOLOGY, INC.
Entity Incorporation, State or Country Code	DE
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
Title of 12(b) Security	Common stock, $0.0001
Trading Symbol	SURF
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		40,676,849
Entity Central Index Key	0001718108
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 99,466	$ 46,755
Marketable securities	3,007	58,406
Prepaid expenses and other current assets	5,123	2,765
Total current assets	107,596	107,926
Property and equipment, net	6,916	7,286
Operating lease right-of-use asset	28,354	14,858
Restricted cash	1,595	1,595
Other assets	209	28
Total assets	144,670	131,693
Current liabilities:
Accounts payable	509	3,384
Accrued expenses and other current liabilities	7,542	8,012
Deferred revenue - related party	0	4,916
Operating lease liability	5,498	2,962
Total current liabilities	13,549	19,274
Deferred revenue - related party, non-current	0	33,676
Operating lease liability, non-current	29,364	16,968
Convertible note payable, non-current	14,593	5,109
Other liabilities	1,100	0
Total liabilities	58,606	75,027
Commitments and contingencies
Stockholders’ equity:
Preferred stock, value, outstanding	0	0
Common stock, value, outstanding	4	3
Additional paid-in capital	215,662	178,155
Accumulated other comprehensive income	4	103
Accumulated deficit	(129,606)	(121,595)
Total stockholders’ equity	86,064	56,666
Total liabilities and stockholders’ equity	$ 144,670	$ 131,693

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	40,616,644	27,893,337
Common stock, outstanding (in shares)	40,616,644	27,893,337

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Collaboration revenue - related party	$ 0	$ 344	$ 38,592	$ 14,921
Operating expenses:
Research and development	9,454	12,916	30,290	40,461
General and administrative	4,904	4,984	14,686	15,494
Total operating expenses	14,358	17,900	44,976	55,955
Loss from operations	(14,358)	(17,556)	(6,384)	(41,034)
Interest and other income, net	(1,416)	678	(1,627)	2,199
Net loss	$ (15,774)	$ (16,878)	$ (8,011)	$ (38,835)
Net loss per share attributable to common stockholders— basic and diluted (in dollars per share)	$ (0.39)	$ (0.61)	$ (0.24)	$ (1.39)
Weighted average common shares outstanding— basic and diluted (in shares)	40,004,555	27,862,544	33,822,682	27,844,591
Comprehensive loss:
Net loss	$ (15,774)	$ (16,878)	$ (8,011)	$ (38,835)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	(50)	(36)	(99)	257
Comprehensive loss	$ (15,824)	$ (16,914)	$ (8,110)	$ (38,578)

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Marketable securities tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Statement of Stockholders Equity (Unaudited) - 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 (in shares) at Dec. 31, 2018		27,772,600
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	211		211
Issuance of common stock upon exercise of stock options (in shares)		58,082
Stock-based compensation expense	1,395		1,395
Unrealized gain (loss) 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 (in shares) at Mar. 31, 2019		27,830,682
Beginning balance at Dec. 31, 2018	102,862	$ 3	169,784	(119)	(66,806)
Beginning balance (in shares) at Dec. 31, 2018		27,772,600
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on marketable securities	257
Net income (loss)	(38,835)
Ending balance at Sep. 30, 2019	68,985	$ 3	174,485	138	(105,641)
Ending balance (in shares) at Sep. 30, 2019		27,882,756
Beginning balance at Mar. 31, 2019	100,393	$ 3	171,390	5	(71,005)
Beginning balance (in shares) at Mar. 31, 2019		27,830,682
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	33		33
Issuance of common stock upon exercise of stock options (in shares)		21,069
Stock-based compensation expense	1,485		1,485
Unrealized gain (loss) on marketable securities	169			169
Net income (loss)	(17,758)				(17,758)
Ending balance at Jun. 30, 2019	84,322	$ 3	172,908	174	(88,763)
Ending balance (in shares) at Jun. 30, 2019		27,851,751
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	11		11
Issuance of common stock upon exercise of stock options (in shares)		31,005
Stock-based compensation expense	1,566		1,566
Unrealized gain (loss) on marketable securities	(36)			(36)
Net income (loss)	(16,878)				(16,878)
Ending balance at Sep. 30, 2019	68,985	$ 3	174,485	138	(105,641)
Ending balance (in shares) at Sep. 30, 2019		27,882,756
Beginning balance at Dec. 31, 2019	$ 56,666	$ 3	178,155	103	(121,595)
Beginning balance (in shares) at Dec. 31, 2019	27,893,337	27,893,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	$ 10		10
Issuance of common stock upon exercise of stock options (in shares)		27,832
Issuance of common stock under stock purchase plan	83		83
Issuance of common stock under stock purchase plan (in shares)		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 (in shares)		91,003
Stock-based compensation expense	1,850		1,850
Unrealized gain (loss) 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 (in shares) at Mar. 31, 2020		28,061,197
Beginning balance at Dec. 31, 2019	$ 56,666	$ 3	178,155	103	(121,595)
Beginning balance (in shares) at Dec. 31, 2019	27,893,337	27,893,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on marketable securities	$ (99)
Net income (loss)	(8,011)
Ending balance at Sep. 30, 2020	$ 86,064	$ 4	215,662	4	(129,606)
Ending balance (in shares) at Sep. 30, 2020	40,616,644	40,616,644
Beginning balance at Mar. 31, 2020	$ 81,566	$ 3	180,418	170	(99,025)
Beginning balance (in shares) at Mar. 31, 2020		28,061,197
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	262		262
Issuance of common stock upon exercise of stock options (in shares)		68,426
Issuance of common stock upon public offering, net of issuance costs	28,766	$ 1	28,765
Issuance of common stock upon public offering, net of issuance costs (in shares)		11,127,590
Stock-based compensation expense	2,000		2,000
Unrealized gain (loss) on marketable securities	(116)			(116)
Net income (loss)	(14,807)				(14,807)
Ending balance at Jun. 30, 2020	97,671	$ 4	211,445	54	(113,832)
Ending balance (in shares) at Jun. 30, 2020		39,257,213
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options	143		143
Issuance of common stock upon exercise of stock options (in shares)		37,234
Issuance of common stock under stock purchase plan	111		111
Issuance of common stock under stock purchase plan (in shares)		40,147
Issuance of common stock upon conversion of convertible note payable	2,000		2,000
Issuance of common stock upon conversion of convertible note payable (in shares)		1,282,050
Stock-based compensation expense	1,963		1,963
Unrealized gain (loss) on marketable securities	(50)			(50)
Net income (loss)	(15,774)				(15,774)
Ending balance at Sep. 30, 2020	$ 86,064	$ 4	$ 215,662	$ 4	$ (129,606)
Ending balance (in shares) at Sep. 30, 2020	40,616,644	40,616,644

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (8,011)	$ (38,835)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization expense	1,260	1,324
Stock-based compensation expense	5,813	4,446
Non-cash interest expense related to note payable	1,484	0
Net amortization of premiums and discounts on marketable securities	(50)	(666)
Loss on disposal of property and equipment	1	1
Non-cash operating lease cost	1,537	865
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,358)	3,262
Other assets	(181)	5
Accounts payable	(2,875)	(1,154)
Accrued expenses and other current liabilities	(1,339)	(301)
Operating lease liability	(101)	(828)
Other liabilities	1,100	0
Deferred revenue - related party	(38,592)	(14,921)
Net cash used in operating activities	(42,312)	(46,802)
Cash flows from investing activities:
Purchases of property and equipment	(22)	(1,407)
Purchases of marketable securities	(650)	(107,784)
Proceeds from sales or maturities of marketable securities	56,000	111,349
Net cash provided by investing activities	55,328	2,158
Cash flows from financing activities:
Proceeds from Convertible Debt	10,000	0
Proceeds from issuance of common stock upon public offering, net	29,086	0
Proceeds from employee stock purchases	194	0
Proceeds from exercise of stock options	415	255
Net cash provided by financing activities	39,695	255
Net increase (decrease) in cash and cash equivalents and restricted cash	52,711	(44,389)
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	101,061	39,721
Supplemental disclosure of cash flow information:
Cash paid for interest	753	0
Supplemental disclosure of non-cash investing and financing activities:
Additional right-of-use asset and related lease liability	15,003	0
Purchases of property and equipment included in accounts payable and accrued expenses	869	12
Conversion of note payable into shares of common stock	$ 2,000	$ 0

Nature of the Business	9 Months Ended
Nature of the Business	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	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™ Sales Agreement (the “2019 Sales Agreement”) with JonesTrading Institutional Services LLC (“JonesTrading”) to issue and sell shares of the Company’s common stock of up to $30,000 in gross proceeds, from time to time during the term of the 2019 Sales Agreement, through an “at-the-market” equity offering program under which JonesTrading acted as the Company’s agent and/or principal (the “2019 ATM Facility”). The 2019 ATM Facility provided that JonesTrading was entitled to compensation for its services in an amount of up to 3.0% of the gross proceeds of any shares sold under the 2019 ATM Facility. The Company had no obligation to sell any shares under the 2019 ATM Facility and could, at any time, suspend solicitation and offers under the 2019 Sales Agreement. In the nine months ended September 30, 2020, the Company sold 11,218,593 shares of common stock at-the-market under the 2019 Sales Agreement, resulting in net proceeds of approximately $29,086. Through September 30, 2020, the Company sold 11,229,174 shares of common stock at-the-market under the 2019 Sales Agreement, resulting in net proceeds of $29,110. As of June 30, 2020, the Company has fully utilized and closed the 2019 ATM Facility. On May 22, 2020, the Company entered into a Capital on Demand™ Sales Agreement (the “2020 Sales Agreement”) with JonesTrading to issue and sell shares of the Company’s common stock of up to $50,000 in gross proceeds, from time to time during the term of the 2020 Sales Agreement, through an “at-the-market” equity offering program under which JonesTrading will act as the Company’s agent and/or principal (the “2020 ATM Facility”). The 2020 ATM Facility provides that JonesTrading will be entitled to compensation for its services in an amount of up to 3.0% of the gross proceeds of any shares sold under the 2020 ATM Facility. The Company has no obligation to sell any shares under the 2020 ATM Facility and may, at any time, suspend solicitation and offers under the 2020 Sales Agreement. Through September 30, 2020, the Company has not sold any shares of common stock at-the-market under the 2020 Sales Agreement. 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 September 30, 2020, the Company had an accumulated deficit of $129,606. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. As of November 10, 2020, the issuance date of this Quarterly Report on Form 10-Q, the Company expects that its cash, cash equivalents and marketable securities of $102,473, 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 the Company cannot predict their scope or the severity of the outbreak, these developments and measures could materially and adversely affect the Company's business, the Company's results of operations and financial condition. The Company is closely monitoring the impact of the COVID-19 pandemic on all aspects of its business and has taken steps to minimize its impact on the Company's business. Although COVID-19 has not yet had a material adverse impact on our operations and our clinical and preclinical programs, the extent to which COVID-19 ultimately impacts the Company's 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 mitigate its impact, among others. Furthermore, for the safety of its employees, the Company has reduced the presence of its employees in the Company's corporate office and is relying on third parties to conduct many of the experiments and studies for its research programs. Certain of the Company's third-party service providers have also experienced shutdowns or other business disruptions. As a result, the Company's ability to conduct its business in the manner and on the timelines presently planned could be materially or negatively affected, which could have a material adverse impact on the Company's business, results of operations and financial condition.

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	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 the Company's 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. The Company has made estimates of the impact of COVID-19 within its 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 September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the condensed consolidated statement of stockholders’ equity for the three and nine months ended September 30, 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 September 30, 2020 and the results of its operations and its cash flows for the nine months ended September 30, 2020 and 2019. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2020 and 2019 are also unaudited. The results for the three and nine months ended September 30, 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, or ASU 2018-18. ASU 2018-18 makes targeted improvements to generally accepted accounting principles for collaborative arrangements, including: (i) clarification that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaborative arrangement participant is a customer in the context of a unit of account, (ii) adding unit-of-account guidance in Topic 808 to align with the guidance in ASC 606, and (iii) a requirement that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under ASC 606 is precluded if the collaborative arrangement participant is not a customer. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. This standard became effective for the Company on January 1, 2020 and the adoption of ASU 2018-18 did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures. 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”). The new standard provides for changes to the disclosure requirements for recurring and nonrecurring fair value measurements under Topic 820. Provisions of ASU 2018-13 including changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty are required to be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments in ASU 2018-13 should be applied retrospectively to all periods presented upon their effective date. ASU 2018-13 is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019, with early adoption permitted. 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 ("ASU 2016-13"), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes may result in earlier recognition of credit losses. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which narrowed the scope and changed the effective date for non-public entities for ASU 2016-13. The FASB subsequently issued supplemental guidance within ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05"). ASU 2019-05 provides an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. For public entities that are Securities and Exchange Commission filers, excluding entities eligible to be smaller reporting companies, ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, ASU 2016-13 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. 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

9 Months Ended

Sep. 30, 2020

Marketable Securities [Abstract]

Marketable Securities

As of September 30, 2020, the fair value of available-for-sale marketable debt securities by type of security was as follows:


	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Marketable debt securities:
U.S. Government agency bonds	3,003		4		—		3,007
	$	3,003	$	4	$	—	$	3,007

The amortized cost and fair value of the Company’s available-for-sale debt securities by contractual maturity are summarized as follows:


	September 30, 2020
	Amortized Cost		Fair Value
Maturing in one year or less	$	3,003	$	3,007
	$	3,003	$	3,007

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 September 30, 2020 and December 31, 2019.

Fair Value of Financial Assets

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

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 September 30, 2020 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	66,221	$	—	$	—	$	66,221
Marketable securities:
U.S. Government agency bonds	—		3,007		—		3,007
	$	66,221	$	3,007	$	—	$	69,228


	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 September 30, 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 nine months ended September 30, 2020 and 2019, there were no transfers between Level 1, Level 2 and Level 3.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Collaboration Agreements

9 Months Ended

Sep. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration Agreements

Collaboration Agreement with Novartis

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 and nine months ended September 30, 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 (formerly SRF373). 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.

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. 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 to collaboration revenue - related party in January 2020.

For the three and nine months ended September 30, 2020 and 2019, the Company recognized the following totals of collaboration revenue – related party:


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
Collaboration revenue - related party	$	—	$	344	$	38,592	$	14,921

The following table presents changes in the Company’s contract liabilities during the nine months ended September 30, 2020:


	December 31, 2019		Additions		Deductions		September 30, 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 the nine months ended September 30, 2020, the Company recognized $38,592 of revenue related to the amounts included in contract liability balance at the beginning of the period. During the three months ended September 30, 2020, the Company did not recognize any revenue included in the contract liability balance at the beginning of the period. As there are no Options remaining eligible for purchase and exercise, the Company’s performance obligations under the Collaboration Agreement have ended.

Stockholders’ Equity	9 Months Ended
Stockholders’ Equity	Sep. 30, 2020
Equity [Abstract]
Stockholders’ Equity	Stockholders’ Equity Common Stock As of September 30, 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 September 30, 2020. As of September 30, 2020 and December 31, 2019, the Company had reserved 22,819,394 and 17,351,095 shares, respectively, of common stock for the exercise of outstanding stock options, the vesting of restricted stock units, shares to be issued under the 2020 ATM Facility, shares to be issued upon the conversion of the Loan Agreement (as defined below), 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 2019 Sales Agreement with JonesTrading to issue and sell up to $30,000 in shares of the Company’s common stock from time to time. In the nine months ended September 30, 2020, the Company sold 11,218,593 shares of common stock at-the-market under the 2019 Sales Agreement, resulting in net proceeds of approximately $29,086. Through September 30, 2020, the Company has sold 11,229,174 shares of common stock at-the-market under the 2019 Sales Agreement for net proceeds of $29,110. As of June 30, 2020, the Company has fully utilized and closed the 2019 ATM Facility. In May 2020, the Company entered into the 2020 Sales Agreement with JonesTrading to issue and sell up to $50,000 in shares of the Company's common stock, from time to time. Through September 30, 2020, the Company has not sold any shares of common stock at-the-market under the 2020 Sales Agreement.

Stock-Based Awards

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

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 September 30, 2020, 642,834 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	1,284,100	3.31
Exercised	(133,492)	3.11
Forfeited	(454,082)	6.83
Outstanding as of September 30, 2020	6,114,639	$	5.53	7.50	$	14,763
Options exercisable at September 30, 2020	3,672,347	$	5.64	6.86	$	8,787
Vested and expected to vest at September 30, 2020	6,114,639	$	5.53	7.50	$	14,763

The weighted average grant-date fair value per share of stock options granted during the nine months ended September 30, 2020 and year ended December 31, 2019 was $2.09 and $2.71, respectively.

As of September 30, 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 September 30, 2020, a total of 724,305 shares of common stock were reserved for issuance under this plan.

For the three and nine months ended September 30, 2020, the Company issued 40,147 and 89,172 shares of common stock under the ESPP, respectively. For the three and nine months ended September 30, 2019, the Company did not issue any shares of common stock under the 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 after eighteen-months as long as the individual remains an employee of the Company at such time. In the three months ended September 30, 2020, the Company granted 10,500 RSUs with the same vesting terms as the February grant.

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	1,071,400	3.22
Vested	—	—
Forfeited	(19,500)	3.18
Unvested restricted stock units as of September 30, 2020	1,051,900	$	3.22

The expense related to RSUs granted to employees was $552 and $1,541 for the three and nine months ended September 30, 2020, respectively.

At September 30, 2020, there was $1,843 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 0.81 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 loss:


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
Research and development expenses	$	709	$	596	$	2,134	$	1,767
General and administrative expenses	1,254		970		3,679		2,679
	$	1,963	$	1,566	$	5,813	$	4,446

As of September 30, 2020, the Company had an aggregate of $10,121 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 1.78 years

Debt

9 Months Ended

Sep. 30, 2020

Debt Disclosure [Abstract]

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 funded on June 5, 2020 (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 eighteen months following the funding date. The interest-only period can be extended by an additional six months, subject to the funding of the Second Tranche Term Loan; and by an additional six 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 14.34%.

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.

In June 2020, the Company drew down the Second Tranche Term Loan and received an additional $10,000 in proceeds. The Company is permitted to make interest-only payments on the First Tranche Term Loan and the Second Tranche Term Loan until January 2022 in accordance with the terms of the Loan Agreement.

In August 2020, the Lender elected to convert $2,000 of the outstanding term loan amount into 1,282,050 shares of the Company's common stock, in accordance with the Loan Agreement. As of September 30, 2020, the outstanding principal balance was $15,500.

The Company recorded interest expense related to the loan facility of $1,469 and $2,237 for the three and nine months ended September 30, 2020, respectively. The fair value of the loan at September 30, 2020 approximates its face amount due to the floating interest rate.

Future principal debt payments on the loan payable are as follows:


	September 30, 2020
2020	$	—
2021	—
2022	7,401
2023	8,099
Total principal payments	15,500
Final fee due at maturity in 2024	779
Total principal payments and final fee	16,279
Unamortized debt discount and final fee	1,686
Note payable	$	14,593

Net Loss per Share

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Net Loss per Share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019

	Basic and diluted net loss per share attributable to common stockholders:
Numerator:
Net loss	$	(15,774)	$	(16,878)	$	(8,011)	$	(38,835)
Denominator:
Weighted average common shares outstanding — basic and diluted	40,004,555		27,862,544		33,822,682		27,844,591
Net loss per share attributable to common stockholders — basic and diluted	$	(0.39)	$	(0.61)	$	(0.24)	$	(1.39)

The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated above because including them would have had an anti-dilutive effect:


	September 30,
	2020	2019
Stock options to purchase common stock	6,114,639	5,512,379
Shares to be issued under the 2018 ESPP	724,305	78,714
RSUs issued and expecting to vest	1,051,900	—
Shares available from conversion of note payable	1,282,050	—
	9,172,894	5,591,093

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company did not provide for any income taxes for the three and nine months ended September 30, 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 September 30, 2020 and December 31, 2019. Management reevaluates the positive and negative evidence at each reporting period. As of September 30, 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. During July 2020, the Company received notice of completion by the Internal Revenue Service ("IRS") for the period ended December 31, 2016. No adjustments were proposed. 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

9 Months Ended

Sep. 30, 2020

Leases [Abstract]

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 assets and operating lease liabilities. All of the Company’s leases qualify as operating leases. 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 10-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 September 30, 2020		Three months ended September 30, 2019		Nine months ended September 30, 2020			Nine months ended September 30, 2019

Operating lease cost	R&D Expense	$	508	$	575	$	1,559		$	1,733
	G&A Expense	829		234		2,454			695
Variable lease costs (1)	R&D Expense	160		191		519			532
	G&A Expense	278		78		853			214
Total lease cost		$	1,775	$	1,078	$	5,385		$	3,174
Weighted-average remaining lease term (in months)						112.64			120.00
Weighted-average discount rate						10.5		%	10.5		%

(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 $1,756 and $4,924 for the three and nine months ended September 30, 2020, respectively.

As of September 30, 2020, the maturities of the Company’s operating lease liabilities were as follows:


Year Ending December 31,
2020	$	1,356
2021	5,529
2022	5,385
2023	5,413
2024	5,533
Thereafter	31,521
Total future lease payments	54,737
Less: Interest	(19,875)
Present value of future lease payments (lease liability)	$	34,862

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 September 30, 2020, future undiscounted cash inflows under the sublease are as follows:


Year Ending December 31,
2020	$	632
2021	2,579
2022	2,635
2023	220
	$	6,066

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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	9 Months Ended
Related Party Transactions	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	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 nine months ended September 30, 2020, the Company recognized $38,592 of collaboration revenue under the Collaboration Agreement. As of September 30, 2020 and 2019, no amounts were due from Novartis. During the three and nine months ended September 30, 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 and nine months ended September 30, 2020, the Company made no payments relating to the agreement. During the three and nine months ended September 30, 2019, the Company paid Vaccinex an aggregate of $425 and $602, respectively, relating to the agreement. The payments were recognized as research and development expense. The amount due by the Company to Vaccinex as of September 30, 2020 was $50. There was no amount due by the Company to Vaccinex as of September 30, 2019.

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 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 the Company's 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. The Company has made estimates of the impact of COVID-19 within its 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 September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the condensed consolidated statement of stockholders’ equity for the three and nine months ended September 30, 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 September 30, 2020 and the results of its operations and its cash flows for the nine months ended September 30, 2020 and 2019. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2020 and 2019 are also unaudited. The results for the three and nine months ended September 30, 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, or ASU 2018-18. ASU 2018-18 makes targeted improvements to generally accepted accounting principles for collaborative arrangements, including: (i) clarification that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaborative arrangement participant is a customer in the context of a unit of account, (ii) adding unit-of-account guidance in Topic 808 to align with the guidance in ASC 606, and (iii) a requirement that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under ASC 606 is precluded if the collaborative arrangement participant is not a customer. This guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within that fiscal year. This standard became effective for the Company on January 1, 2020 and the adoption of ASU 2018-18 did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures. 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”). The new standard provides for changes to the disclosure requirements for recurring and nonrecurring fair value measurements under Topic 820. Provisions of ASU 2018-13 including changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty are required to be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments in ASU 2018-13 should be applied retrospectively to all periods presented upon their effective date. ASU 2018-13 is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019, with early adoption permitted. 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 ("ASU 2016-13"), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes may result in earlier recognition of credit losses. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which narrowed the scope and changed the effective date for non-public entities for ASU 2016-13. The FASB subsequently issued supplemental guidance within ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05"). ASU 2019-05 provides an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. For public entities that are Securities and Exchange Commission filers, excluding entities eligible to be smaller reporting companies, ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, ASU 2016-13 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. 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)

9 Months Ended

Sep. 30, 2020

Marketable Securities [Abstract]

Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security

As of September 30, 2020, the fair value of available-for-sale marketable debt securities by type of security was as follows:


	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Marketable debt securities:
U.S. Government agency bonds	3,003		4		—		3,007
	$	3,003	$	4	$	—	$	3,007

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:


	September 30, 2020
	Amortized Cost		Fair Value
Maturing in one year or less	$	3,003	$	3,007
	$	3,003	$	3,007

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)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured at Fair Value on Recurring Basis


	Fair Value Measurements as of September 30, 2020 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	66,221	$	—	$	—	$	66,221
Marketable securities:
U.S. Government agency bonds	—		3,007		—		3,007
	$	66,221	$	3,007	$	—	$	69,228


	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 Agreements (Tables)

9 Months Ended

Sep. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Collaboration Revenue Related Party

For the three and nine months ended September 30, 2020 and 2019, the Company recognized the following totals of collaboration revenue – related party:


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
Collaboration revenue - related party	$	—	$	344	$	38,592	$	14,921

Summary of Changes in Contract Liabilities

The following table presents changes in the Company’s contract liabilities during the nine months ended September 30, 2020:


	December 31, 2019		Additions		Deductions		September 30, 2020
Contract liabilities (1)
Total deferred revenue - related party	$	38,592	$	—	$	(38,592)	$	—

Stock-Based Awards (Tables)

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [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	1,284,100	3.31
Exercised	(133,492)	3.11
Forfeited	(454,082)	6.83
Outstanding as of September 30, 2020	6,114,639	$	5.53	7.50	$	14,763
Options exercisable at September 30, 2020	3,672,347	$	5.64	6.86	$	8,787
Vested and expected to vest at September 30, 2020	6,114,639	$	5.53	7.50	$	14,763

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	1,071,400	3.22
Vested	—	—
Forfeited	(19,500)	3.18
Unvested restricted stock units as of September 30, 2020	1,051,900	$	3.22

Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Stock Awards


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019
Research and development expenses	$	709	$	596	$	2,134	$	1,767
General and administrative expenses	1,254		970		3,679		2,679
	$	1,963	$	1,566	$	5,813	$	4,446

Debt (Tables)

9 Months Ended

Sep. 30, 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:


	September 30, 2020
2020	$	—
2021	—
2022	7,401
2023	8,099
Total principal payments	15,500
Final fee due at maturity in 2024	779
Total principal payments and final fee	16,279
Unamortized debt discount and final fee	1,686
Note payable	$	14,593

Net Loss per Share (Tables)

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	Three months ended September 30,				Nine months ended September 30,
	2020		2019		2020		2019

	Basic and diluted net loss per share attributable to common stockholders:
Numerator:
Net loss	$	(15,774)	$	(16,878)	$	(8,011)	$	(38,835)
Denominator:
Weighted average common shares outstanding — basic and diluted	40,004,555		27,862,544		33,822,682		27,844,591
Net loss per share attributable to common stockholders — basic and diluted	$	(0.39)	$	(0.61)	$	(0.24)	$	(1.39)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated above because including them would have had an anti-dilutive effect:


	September 30,
	2020	2019
Stock options to purchase common stock	6,114,639	5,512,379
Shares to be issued under the 2018 ESPP	724,305	78,714
RSUs issued and expecting to vest	1,051,900	—
Shares available from conversion of note payable	1,282,050	—
	9,172,894	5,591,093

Leases (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2020		Three months ended September 30, 2019		Nine months ended September 30, 2020			Nine months ended September 30, 2019

Operating lease cost	R&D Expense	$	508	$	575	$	1,559		$	1,733
	G&A Expense	829		234		2,454			695
Variable lease costs (1)	R&D Expense	160		191		519			532
	G&A Expense	278		78		853			214
Total lease cost		$	1,775	$	1,078	$	5,385		$	3,174
Weighted-average remaining lease term (in months)						112.64			120.00
Weighted-average discount rate						10.5		%	10.5		%

Schedule of Maturities of Operating Lease Liabilities

As of September 30, 2020, the maturities of the Company’s operating lease liabilities were as follows:


Year Ending December 31,
2020	$	1,356
2021	5,529
2022	5,385
2023	5,413
2024	5,533
Thereafter	31,521
Total future lease payments	54,737
Less: Interest	(19,875)
Present value of future lease payments (lease liability)	$	34,862

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 September 30, 2020, future undiscounted cash inflows under the sublease are as follows:


Year Ending December 31,
2020	$	632
2021	2,579
2022	2,635
2023	220
	$	6,066

Nature of the Business - Additional Information (Details) - USD ($)			1 Months Ended		9 Months Ended	17 Months Ended
	May 22, 2020	May 01, 2019	May 31, 2020	May 31, 2019	Sep. 30, 2020	Sep. 30, 2020	Nov. 10, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Accumulated deficit					$ (129,606,000)	$ (129,606,000)		$ (121,595,000)
Operating expenses and capital expenditure requirements (in months)					12 months
Subsequent Event
Class of Stock [Line Items]
Cash, cash equivalents and marketable securities							$ 102,473,000
2019 ATM Facility
Class of Stock [Line Items]
Common stock, issued (in shares)					11,218,593	11,229,174
Net proceeds from issuance of common stock					$ 29,086,000	$ 29,110,000
2019 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%
2020 ATM Facility \| Maximum
Class of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 50,000,000		$ 50,000,000
Percentage of gross proceeds of shares sold for compensation	3.00%

Marketable Securities - Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,003	$ 58,303
Gross Unrealized Gains	4	104
Gross Unrealized Losses	0	(1)
Fair Value	3,007	58,406
U.S. Treasury notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		42,795
Gross Unrealized Gains		73
Gross Unrealized Losses		0
Fair Value		42,868
U.S. Government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,003	15,508
Gross Unrealized Gains	4	31
Gross Unrealized Losses	0	(1)
Fair Value	$ 3,007	$ 15,538

Marketable Securities - Summary of Fair Value of Available-for-sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Abstract]
Maturing in one year or less, Amortized Cost	$ 3,003	$ 58,303
Maturing in one year or less, Fair Value	$ 3,007	$ 58,406

Marketable Securities - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Abstract]
Investments in other-than-temporary decline in fair value	$ 0	$ 0

Fair Value of Financial Assets - Additional Information (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 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 Agreements - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2016	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Preferred stock shares issued to related party (in shares)			0		0		0
Collaboration revenue - related party			$ 0	$ 344,000	$ 38,592,000	$ 14,921,000
Novartis Collaboration \| Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment for reimbursement of manufacturing costs incurred			$ 0	$ 0	0	$ 0
Collaboration revenue - related party	$ 38,592,000
Novartis Collaboration \| Novartis Institutes for Biomedical Research, Inc. \| Up Front Payment Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from collaboration arrangement		$ 70,000,000
Novartis Collaboration \| Novartis Institutes for Biomedical Research, Inc. \| Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment					$ 525,000,000
Novartis Collaboration \| Series A One Redeemable Convertible Preferred Stock \| Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Preferred stock shares issued to related party (in shares)		2,000,000
Novartis Collaboration \| Private Placement \| Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock, issued (in shares)		766,666
Share price (in dollars per share)		$ 15.00
Proceeds from stock issued to related party in private placement		$ 11,500,000
Minimum \| Novartis Collaboration \| Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of share holding		5.00%

Collaboration Agreements - Schedule of Collaboration Revenue Related Party (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party		$ 0	$ 344	$ 38,592	$ 14,921
Novartis Institutes for Biomedical Research, Inc. \| Novartis Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party	$ 38,592
ASU 2014-09 \| Novartis Institutes for Biomedical Research, Inc. \| Novartis Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party		$ 0	$ 344	$ 38,592	$ 14,921

Fair Value of Financial Assets - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	$ 69,228	$ 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	66,221	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		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	3,007	15,538
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	66,221	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	66,221	30,490
Level 1 \| 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		0
Level 1 \| Marketable Securities \| U.S. Treasury Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis		0
Level 1 \| 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	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	3,007	60,906
Level 2 \| Cash Equivalents \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	0	0
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		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	3,007	15,538
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	0	0
Level 3 \| Cash Equivalents \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	0	0
Level 3 \| 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		0
Level 3 \| Marketable Securities \| U.S. Treasury Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis		0
Level 3 \| 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	$ 0	$ 0