Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2019	Aug. 01, 2019
Document And Entity Information
Entity Registrant Name	Corvus Pharmaceuticals, Inc.
Entity Central Index Key	0001626971
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	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		29,390,400
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 30,183	$ 39,196
Marketable securities	66,657	75,401
Prepaid and other current assets	1,305	992
Total current assets	98,145	115,589
Property and equipment, net	1,824	2,180
Operating lease right-of-use asset	2,634
Other assets	513	463
Total assets	103,116	118,232
Current liabilities:
Accounts payable	2,638	1,998
Operating lease liability current	820
Accrued and other liabilities	7,244	5,029
Total current liabilities	10,702	7,027
Operating lease liability noncurrent	2,760
Other liabilities		869
Total liabilities	13,462	7,896
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock: $0.0001 par value; 10,000,000 shares authorized at June 30, 2019 and December 31, 2018; 0 shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock: $0.0001 par value; 290,000,000 shares authorized at June 30, 2019 and December 31, 2018; 29,348,400 and 29,323,930 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	284,706	280,840
Accumulated other comprehensive income (loss)	39	(34)
Accumulated deficit	(195,094)	(170,473)
Total stockholders' equity	89,654	110,336
Total liabilities and stockholders' equity	$ 103,116	$ 118,232

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	290,000,000	290,000,000
Common stock, shares issued	29,348,400	29,323,930
Common stock, shares outstanding	29,348,400	29,323,930

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 10,640	$ 9,715	$ 20,059	$ 21,818
General and administrative	2,956	2,543	5,842	5,084
Total operating expenses	13,596	12,258	25,901	26,902
Loss from operations	(13,596)	(12,258)	(25,901)	(26,902)
Interest income and other expense, net	618	627	1,280	970
Net loss	$ (12,978)	$ (11,631)	$ (24,621)	$ (25,932)
Net loss per share, basic and diluted (in dollars per share)	$ (0.44)	$ (0.40)	$ (0.84)	$ (1.01)
Shares used to compute net loss per share, basic and diluted (in shares)	29,309,150	28,979,514	29,301,505	25,785,543
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	$ 28	$ 19	$ 73	$ 21
Comprehensive loss	$ (12,950)	$ (11,612)	$ (24,548)	$ (25,911)

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Common Stock.	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balance at Dec. 31, 2017	$ 2,000	$ 208,408,000	$ (41,000)	$ (123,534,000)	$ 84,835,000
Balance (in shares) at Dec. 31, 2017	21,041,250
Increase (Decrease) in Stockholders' Deficit
Issuance of common stock	$ 1,000	64,876,000			64,877,000
Issuance of stock (in shares)	8,117,647
Common stock issued on exercise of stock options		7,000			7,000
Common stock issued on exercise of stock options (in shares)	24,584
Vesting of restricted stocks issued upon early exercise of stock options		7,000			7,000
Stock-based compensation expense		1,801,000			1,801,000
Unrealized loss on marketable securities			2,000		2,000
Net loss				(14,301,000)	(14,301,000)
Balance at Mar. 31, 2018	$ 3,000	275,099,000	(39,000)	(137,835,000)	137,228,000
Balance (in shares) at Mar. 31, 2018	29,183,481
Balance at Dec. 31, 2017	$ 2,000	208,408,000	(41,000)	(123,534,000)	84,835,000
Balance (in shares) at Dec. 31, 2017	21,041,250
Increase (Decrease) in Stockholders' Deficit
Net loss					(25,932,000)
Balance at Jun. 30, 2018	$ 3,000	276,882,000	(20,000)	(149,466,000)	127,399,000
Balance (in shares) at Jun. 30, 2018	29,197,857
Balance at Mar. 31, 2018	$ 3,000	275,099,000	(39,000)	(137,835,000)	137,228,000
Balance (in shares) at Mar. 31, 2018	29,183,481
Increase (Decrease) in Stockholders' Deficit
Common stock issued on exercise of stock options		41,000			41,000
Common stock issued on exercise of stock options (in shares)	14,376
Vesting of restricted stocks issued upon early exercise of stock options		6,000			6,000
Stock-based compensation expense		1,736,000			1,736,000
Unrealized loss on marketable securities			19,000		19,000
Net loss				(11,631,000)	(11,631,000)
Balance at Jun. 30, 2018	$ 3,000	276,882,000	(20,000)	(149,466,000)	127,399,000
Balance (in shares) at Jun. 30, 2018	29,197,857
Balance at Dec. 31, 2018	$ 3,000	280,840,000	(34,000)	(170,473,000)	110,336,000
Balance (in shares) at Dec. 31, 2018	29,323,930
Increase (Decrease) in Stockholders' Deficit
Common stock issued on exercise of stock options	$ 2,970	1,000			1,000
Vesting of restricted stocks issued upon early exercise of stock options		5,000			5,000
Stock-based compensation expense		1,953,000			1,953,000
Unrealized loss on marketable securities			45,000		45,000
Net loss				(11,643,000)	(11,643,000)
Balance at Mar. 31, 2019	$ 3,000	282,799,000	11,000	(182,116,000)	100,697,000
Balance (in shares) at Mar. 31, 2019	29,326,900
Balance at Dec. 31, 2018	$ 3,000	280,840,000	(34,000)	(170,473,000)	110,336,000
Balance (in shares) at Dec. 31, 2018	29,323,930
Increase (Decrease) in Stockholders' Deficit
Net loss					(24,621,000)
Balance at Jun. 30, 2019	$ 3,000	284,706,000	39,000	(195,094,000)	89,654,000
Balance (in shares) at Jun. 30, 2019	29,348,400
Balance at Mar. 31, 2019	$ 3,000	282,799,000	11,000	(182,116,000)	100,697,000
Balance (in shares) at Mar. 31, 2019	29,326,900
Increase (Decrease) in Stockholders' Deficit
Common stock issued on exercise of stock options		5,000			5,000
Common stock issued on exercise of stock options (in shares)	21,500
Vesting of restricted stocks issued upon early exercise of stock options		4,000			4,000
Stock-based compensation expense		1,898,000			1,898,000
Unrealized loss on marketable securities			28,000		28,000
Net loss				(12,978,000)	(12,978,000)
Balance at Jun. 30, 2019	$ 3,000	$ 284,706,000	$ 39,000	$ (195,094,000)	$ 89,654,000
Balance (in shares) at Jun. 30, 2019	29,348,400

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net loss	$ (24,621)	$ (25,932)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	372	439
Accretion related to marketable securities	(384)	(232)
Stock-based compensation	3,851	3,536
Other	86	(229)
Changes in operating assets and liabilities:
Prepaid and other current assets	(313)	(9)
Other assets	(50)	(323)
Accounts payable	640	(1,199)
Accrued and other liabilities	2,215	2,015
Net cash used in operating activities	(18,204)	(21,934)
Cash flows from investing activities
Purchases of marketable securities	(64,502)	(99,455)
Maturities of marketable securities	73,703	39,479
Purchase of property and equipment	(16)	(60)
Net cash provided by (used in) investing activities	9,185	(60,036)
Cash flows from financing activities
Proceeds from issuance of common stock, net (includes $30,850 in aggregate gross proceeds from related parties for the six months ended June 30, 2018		64,877
Proceeds from exercise of common stock options	6	55
Net cash provided by financing activities	6	64,932
Net decrease in cash and cash equivalents	(9,013)	(17,038)
Cash and cash equivalents at beginning of the period	39,196	45,106
Cash and cash equivalents at end of the period	$ 30,183	$ 28,068

Organization	6 Months Ended
Organization	Jun. 30, 2019
Organization
Organization	1. Organization Corvus Pharmaceuticals, Inc. (“Corvus” or the “Company”) was incorporated in Delaware on January 27, 2014 and commenced operations in November 2014. Corvus is a clinical-stage biopharmaceutical company focused on the development and commercialization of precisely targeted oncology therapies. The Company’s operations are located in Burlingame, California. Initial Public Offering On March 22, 2016, the Company’s registration statement on Form S-1 (File No. 333-208850) relating to its initial public offering (“IPO”) of its common stock was declared effective by the Securities and Exchange Commission (“SEC”) and the shares of its common stock began trading on the Nasdaq Global Market on March 23, 2016. The public offering price of the shares sold in the IPO was $15.00 per share. The IPO closed on March 29, 2016, pursuant to which the Company sold 4,700,000 shares of its common stock. On April 26, 2016, the Company sold an additional 502,618 shares of its common stock to the underwriters upon partial exercise of their over-allotment option, at the initial offering price of $15.00 per share. The Company received aggregate net proceeds of approximately $70.6 million, net of underwriting discounts, commissions and offering expenses payable by the Company. Immediately prior to the consummation of the IPO, all outstanding shares of convertible preferred stock were converted into common stock. Follow-on Public Offering In March 2018, the Company completed a follow-on public offering in which the Company sold 8,117,647 shares of common stock at a price of $8.50 per share, which included 1,058,823 shares issued pursuant to the underwriters’ exercise of their option to purchase additional shares of common stock. The aggregate net proceeds received by the Company from the offering were approximately $64.9 million, net of underwriting discounts and commissions and offering expenses payable by the Company.

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Company’s functional and reporting currency is the U.S. dollar. The accompanying condensed financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and discharge of liabilities in the normal course of business. Since its inception, the Company has incurred significant losses and negative cash flows from operations. As of June 30, 2019, the Company had an accumulated deficit of $195.1 million and cash, cash equivalents and marketable securities of $96.8 million. The Company has financed its operations primarily with the proceeds from the sale of stock. The Company will need to raise additional capital to meet its business objectives. The Company believes that its current cash, cash equivalents and marketable securities will be sufficient to fund its planned expenditures and meet its obligations through at least the next twelve months from the issuance of these financial statements. Unaudited Interim Financial Information The accompanying interim condensed financial statements and related disclosures are unaudited, have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the results of operations for the periods presented. The year-end condensed balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The condensed results of operations for the six months ended June 30, 2019 are not necessarily indicative of the results to be expected for the full year or for any other future year or interim period. The accompanying condensed financial statements should be read in conjunction with the audited financial statements and the related notes for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 7, 2019. Use of Estimates The preparation of the Company’s condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed financial statements and accompanying notes. Actual results could differ from such estimates. Concentrations of Credit Risk and Other Risks and Uncertainties Substantially all of the Company’s cash and cash equivalents are deposited in accounts with two financial institutions that management believes are of high credit quality. Such deposits may, at times, exceed federally insured limits. The Company maintains its cash with an accredited financial institution and accordingly, such funds are subject to minimal credit risk. The Company’s marketable securities consist of investments in U.S. government agency securities and corporate debt obligations, which can be subject to certain credit risks. However, the Company mitigates the risks by investing in high-grade instruments, limiting its exposure to any one issuer, and monitoring the ongoing creditworthiness of the financial institutions and issuers. The Company has not experienced any losses on its deposits of cash, cash equivalents or marketable securities. The Company is subject to a number of risks similar to other early stage biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, its reliance on third parties to conduct its clinical trials, the need to obtain marketing approval for its product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, its right to develop and commercialize its product candidates pursuant to the terms and conditions of the licenses granted to the Company, and protection of proprietary technology. If the Company does not successfully commercialize or partner any of its product candidates, it will be unable to generate product revenue or achieve profitability. Segments Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision‑maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment, that of the development of and commercialization of precisely targeted oncology therapies. Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 to its financial statements for the year ended December 31, 2018, included in its Annual Report on Form 10-K. Other than the adoption of ASU No. 2016-02, Leases (Topic 842) described below, there have been no material changes to the Company’s significant accounting policies during the six months ended June 30, 2019. Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use (ROU) model that requires a lessee to recognize an ROU asset and lease liability on the balance sheet. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the statement of operations. The Company adopted the new standard on January 1, 2019 and has elected the ‘package of practical expedients’, which permit it not to reassess under the new standard its prior conclusions about lease identification, lease classification and initial direct costs. The Company did not elect the use-of-hindsight or the practical expedient pertaining to land easements; the latter is not applicable to the Company. See also Note 11.

Net Loss per Share

6 Months Ended

Jun. 30, 2019

Net Loss per Share

Net Loss per Share

3. Net Loss per Share

The following table shows the calculation of net loss per share (in thousands, except share and per share data):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Numerator:
Net loss - basic and diluted	$	(12,978)	$	(11,631)	$	(24,621)	$	(25,932)
Denominator:
Weighted average common shares outstanding		29,329,229		29,194,462		29,328,075		26,048,630
Less: weighted average common shares subject to repurchase		(20,079)		(214,948)		(26,570)		(263,087)
Weighted average common shares outstanding used to compute basic and diluted net loss per share		29,309,150		28,979,514		29,301,505		25,785,543
Net loss per share, basic and diluted	$	(0.44)	$	(0.40)	$	(0.84)	$	(1.01)

The amounts in the table below were excluded from the calculation of diluted net loss per share, due to their anti‑dilutive effect:


	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2019	2018	2019	2018
Common stock subject to repurchase	12,384	172,955	12,384	172,955
Outstanding options	4,157,154	3,019,438	4,157,154	3,019,438
Total shares of common stock equivalents	4,169,538	3,192,393	4,169,538	3,192,393

Fair Value Measurements

6 Months Ended

Jun. 30, 2019

Fair Value Measurements

Fair Value Measurements

4. Fair Value Measurements

Financial assets and liabilities are measured and recorded at fair value. The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs:

Level 1—Quoted prices in active markets for identical assets or liabilities

Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly

Level 3—Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability

There have been no transfers of assets and liabilities between levels of hierarchy.

The Company’s Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs.

The following tables present information as of June 30, 2019 and December 31, 2018 about the Company’s assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy the Company utilized to determine such fair values (in thousands):


	June 30, 2019
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	29,679	$	—	$	—	$	29,679
Marketable securities		—		66,657		—		66,657
	$	29,679	$	66,657	$	—	$	96,336


	December 31, 2018
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	38,698	$	—	$	—	$	38,698
Marketable securities		—		75,401		—		75,401
	$	38,698	$	75,401	$	—	$	114,099

As of June 30, 2019, marketable securities had a maximum remaining maturity of eleven months.

As of June 30, 2019 and December 31, 2018, the fair value of available for sale marketable securities by type of security were as follows (in thousands):


	June 30, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Government agency securities	$	32,837	$	18	$	—	$	32,855
Corporate debt obligations		33,781		26		(5)		33,802
	$	66,618	$	44	$	(5)	$	66,657


	December 31, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Government agency securities	$	49,124	$	—	$	(27)	$	49,097
Corporate debt obligations		26,311		—		(7)		26,304
	$	75,435	$	—	$	(34)	$	75,401

- 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

License and Collaboration Agreements	6 Months Ended
License and Collaboration Agreements	Jun. 30, 2019
License And Collaboration Agreements [Abstract]
License and Collaboration Agreements	5. License and Collaboration Agreements Scripps Licensing Agreement In December 2014, the Company entered into a license agreement with The Scripps Research Institute (“Scripps”), pursuant to which it was granted a non‑exclusive, world‑wide license for all fields of use under Scripps’ rights in certain know‑how and technology related to a mouse hybridoma clone expressing an anti‑human CD73 antibody, and to progeny, mutants or unmodified derivatives of such hybridoma and any antibodies expressed by such hybridoma, from which we developed CPI-006. Scripps also granted the Company the right to grant sublicenses in conjunction with other proprietary rights the Company holds, or to others collaborating with or performing services for the Company. Under this license agreement, Scripps has agreed not to grant any additional commercial licenses with respect to such materials, other than march‑in rights granted to the U.S. government. Upon execution of the agreement, the Company made a one‑time cash payment to Scripps of $10,000 in 2015 and is also obligated to pay a minimum annual fee to Scripps of $25,000. The one‑time cash payment was recorded as research and development expense as technological feasibility of the asset had not been established and there was no alternative future use. A minimum annual fee payment is due on each anniversary of the effective date of the agreement for the term of the agreement. The Company is also required to make performance‑based cash payments upon successful completion of clinical and sales milestones. The aggregate potential milestone payments are $2.6 million. The Company is also required to pay royalties on net sales of licensed products (including CPI-006) sold by it, its affiliates and its sublicensees at a rate in the low‑single digits. In addition, should the Company sublicense the rights licensed under the agreement, it has agreed to pay a percentage of sublicense revenue received at specified rates that start at double digit percentages and decrease to single digit percentages based on the elapsed time from the effective date of the agreement and the time of entry into such sublicense. To date, no milestone payments have been made. The Company’s license agreement with Scripps will terminate upon expiration of its obligation to pay royalties to Scripps under the license agreement. The Company’s license agreement with Scripps is terminable by the consent of the parties, at will by the Company upon providing 90 days written notice to Scripps, or by Scripps for certain material breaches, or if the Company undergoes a bankruptcy event. In addition, Scripps may terminate the license on a product‑by‑product basis, or the entire agreement, if the Company fails to meet specified diligence obligations related to the development and commercialization of licensed products. Scripps may also terminate the agreement after the third anniversary of the effective date of the agreement if it reasonably believes, based on reports the Company provides to Scripps, that the Company has not used commercially reasonable efforts as required under the agreement, subject to a specified notice and cure period. Vernalis Licensing Agreement In February 2015, the Company entered into a license agreement with Vernalis (R&D) Limited (“Vernalis”), which was subsequently amended as of November 5, 2015, and, pursuant to which the Company was granted an exclusive, worldwide license under certain patent rights and know-how, including a limited right to grant sublicenses, for all fields of use to develop, manufacture and commercialize products containing certain adenosine receptor antagonists, including ciforadenant (formerly CPI-444). Pursuant to this agreement, the Company made a one-time cash payment to Vernalis in the amount of $1.0 million, which was recorded as research and development expense as technological feasibility of the asset had not been established and there was no alternative future use. The Company is also required to make cash milestone payments to Vernalis upon the successful completion of clinical and regulatory milestones for licensed products depending on the indications for which such licensed products are developed and upon achievement of certain sales milestones. In February 2017, the Company made a milestone payment of $3.0 million to Vernalis following the expansion of a cohort of patients with renal cell cancer treated with single agent ciforadenant in the Company’s Phase 1/1b clinical trial. The aggregate potential milestone payments are approximately $220 million for all indications. The Company has also agreed to pay Vernalis tiered incremental royalties based on the annual net sales of licensed products containing ciforadenant on a product‑by‑product and country‑by‑country basis, subject to certain offsets and reductions. The tiered royalty rates for products containing ciforadenant range from the mid‑single digits up to the low‑double digits on a country‑by‑country net sales basis. The royalties on other licensed products that do not include ciforadenant also increase with the amount of net sales on a product-by-product and country‑by‑country basis and range from the low‑single digits up to the mid‑single digits on a country‑by‑country net sales basis. The Company is also obligated to pay to Vernalis certain sales milestones as indicated above when worldwide net sales reach specified levels over an agreed upon time period. The agreement will expire on a product‑by‑product and country‑by‑country basis upon the expiration of the Company’s payment obligations to Vernalis in respect of a particular product and country. Both parties have the right to terminate the agreement for an uncured material breach by the other party. The Company may also terminate the agreement at its convenience by providing 90 days written notice, provided that the Company has not received notice of its own default under the agreement at the time the Company exercises such termination right. Vernalis may also terminate the agreement if the Company challenges a licensed patent or undergoes a bankruptcy event. Genentech Collaboration Agreements In October 2015, the Company entered into a clinical trial collaboration agreement with Genentech to evaluate the safety, tolerability and preliminary efficacy of ciforadenant combined with Genentech’s investigational cancer immunotherapy, Tecentriq (atezolizumab), a fully humanized monoclonal antibody targeting protein programmed cell death ligand 1(“PD-L1”), in a variety of solid tumors in a Phase 1/1b clinical trial. Pursuant to this agreement, the Company will be responsible for the conduct and cost of the relevant studies, under the supervision of a joint development committee made up of representatives of the Company and representatives of Genentech. Genentech will supply Tecentriq. As part of the agreement, the Company granted Genentech certain rights of first negotiation to participate in future clinical trials that the Company may conduct evaluating the administration of ciforadenant in combination with an anti-PD-1 or anti-PD-L1 antibody. If the Company and Genentech do not reach agreement on the terms of any such participation by Genentech within a specified time period, the Company retains the right to collaborate with third parties in such activities. The Company also granted Genentech certain rights of first negotiation should it decide to license development and commercialization rights to ciforadenant. Should the Company and Genentech not reach agreement on the terms of such a license within a specified time period, it retains the right to enter into a license with another third party. The Company and Genentech each have the right to terminate the agreement for material breach by the other party. In addition, the agreement may be terminated by either party due to safety considerations, if directed by a regulatory authority or if development of ciforadenant or Tecentriq is discontinued. Further, the agreement will expire after a set period of time following the provision by the Company of the final clinical study report to Genentech. In May, 2017, the Company signed a second clinical trial collaboration agreement with Genentech. Under the second agreement, ciforadenant administered in combination with Tecentriq is being evaluated in a Phase 1b/2 randomized, controlled clinical study, known as Morpheus, as second-line therapy in patients with non-small cell lung cancer who are resistant and/or refractory to prior therapy with an anti-PD-(L)1 antibody. The patients in the Morpheus trial are currently in the follow-up phase of the trial. Genentech is responsible for the conduct of the study and the parties share the cost of the Morpheus trial, which began enrolling patients in the fourth quarter of 2017. The Company is responsible for supplying ciforadenant and retains global development and commercialization rights to ciforadenant. The Company and Genentech each have the right to terminate the agreement for material breach by the other party. In addition, the agreement may be terminated by either party due to safety considerations, if directed by a regulatory authority or if development of ciforadenant or Tecentriq is discontinued.

Balance Sheet Components

6 Months Ended

Jun. 30, 2019

Balance Sheet Components

Balance Sheet Components

6. Balance Sheet Components (in thousands)


	June 30,		December 31,
	2019		2018
Prepaid and Other Current Assets
Interest receivable	$	253	$	337
Prepaid research and development manufacturing expenses		—		75
Prepaid facility expenses		152		149
Prepaid insurance		398		166
Other		502		265
	$	1,305	$	992
Property and Equipment
Laboratory equipment	$	2,388	$	2,371
Computer equipment and purchased software		142		142
Leasehold improvements		2,084		2,084
		4,614		4,597
Less: accumulated depreciation and amortization		(2,790)		(2,417)
	$	1,824	$	2,180
Accrued and Other Liabilities
Accrued clinical trial related	$	2,923	$	2,718
Accrued manufacturing expense		2,518		1,077
Personnel related		1,345		649
Deferred rent		—		160
Accrued legal and accounting		175		77
Other accrued expenses		283		348
	$	7,244	$	5,029
Other Liabilities
Deferred rent	$	—	$	869
	$	—	$	869

Common Stock

6 Months Ended

Jun. 30, 2019

Common Stock

Common Stock

7. Common Stock

As of June 30, 2019, the amended and restated certificate of incorporation authorizes the Company to issue 290 million shares of common stock and 10 million shares of preferred stock.

Each share of common stock is entitled to one vote. Common stockholders are entitled to dividends if and when declared by the board of directors. As of June 30, 2019, no dividends on common stock had been declared.

In September 2017, the Company entered into a sales agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”) to sell shares of the Company’s common stock, from time to time, with aggregate gross sales proceeds of up to $125,000,000, through an at-the-market equity offering program under which Cowen will act as its sales agent. The issuance and sale of shares of common stock by the Company pursuant to the Sales Agreement are deemed an “at-the-market” offering under the Securities Act of 1933, as amended. Cowen is entitled to compensation for its services equal to up to 3.0% of the gross proceeds of any shares of common stock sold through Cowen under the Sales Agreement. During the six months ended June 30, 2019, the Company received no proceeds from the sale of shares of common stock pursuant to the Sales Agreement.

The Company has reserved shares of common stock for issuance as follows:


	June 30,	December 31,
	2019	2018
Shares available for future option grants	3,253,272	2,486,637
Outstanding options	4,157,154	3,778,259
Unvested restricted common stock (founders and early exercise of stock options)	12,384	43,076
Shares reserved for employee stock purchase plan	400,000	400,000
Total	7,822,810	6,707,972

Stock Option Plans

6 Months Ended

Jun. 30, 2019

Stock Option Plans

Stock Option Plans

8. Stock Option Plans

In February 2014, the Company adopted the 2014 Equity Incentive Plan (the “2014 Plan”), which was subsequently amended in November 2014, July 2015 and September 2015, under which it granted incentive stock options (“ISOs”) or non-qualified stock options (“NSOs”). Terms of stock agreements, including vesting requirements, are determined by the board of directors or a committee authorized by the board of directors, subject to the provisions of the 2014 Plan. In general, awards granted by the Company vest over four years and have a maximum exercise term of 10 years. The 2014 Plan provides that grants must be at an exercise price of 100% of fair market value of the Company’s common stock as determined by the board of directors on the date of the grant.

In connection with the consummation of the IPO in March 2016, the 2016 Equity Incentive Award Plan (the “2016 Plan”), became effective. Under the 2016 Plan, incentive stock options, non-statutory stock options, stock purchase rights and other stock-based awards may be granted. Terms of stock agreements, including vesting requirements, are determined by the board of directors or a committee authorized by the board of directors, subject to the provisions of the 2016 Plan. In general, awards granted by the Company vest over four years and have a maximum exercise term of 10 years. The 2016 Plan provides that grants must be at an exercise price of 100% of fair market value of the Company’s common stock as determined by the board of directors on the date of the grant. In conjunction with adopting the 2016 Plan, the 2014 Plan was terminated and no further awards will be granted under the 2014 Plan. Options outstanding under the 2014 Plan as of the effective date of the 2016 Plan that are forfeited or lapse unexercised may be re-issued under the 2016 Plan, up to a maximum of 1,136,229 shares.

Activity under the Company’s stock option plans is set forth below:


		Options Outstanding
			Weighted ‑
	Shares		Average
	Available	Number of	Exercise
	for Grant	Options	Price
Balance at December 31, 2018	2,486,637	3,778,259	$	10.32
Additional shares authorized	1,170,000	—		—
Options granted	(417,000)	417,000		3.87
Options exercised	—	(24,470)		0.28
Options forfeited	13,635	(13,635)		11.86
Balance at June 30, 2019	3,253,272	4,157,154	$	9.73

Stock-Based Compensation

6 Months Ended

Jun. 30, 2019

Stock-Based Compensation

Stock-Based Compensation

9. Stock‑Based Compensation

The Company’s results of operations include expenses relating to employee and non‑employee stock‑based awards as follows (in thousands):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Research and development	$	800	$	785	$	1,598	$	1,545
General and administrative		1,098		951		2,253		1,991
Total	$	1,898	$	1,736	$	3,851	$	3,536

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2019
Income Taxes
Income Taxes	10. Income Taxes During the three and six months ended June 30, 2019 and 2018, the Company recorded no income tax benefits for the net operating losses (NOLs) incurred due to the uncertainty of realizing a benefit from those items. On December 22, 2017, the 2017 Tax Cuts and Jobs Act (the "Tax Act") was enacted into law and the new legislation contains several key tax provisions that affected the Company, including a reduction of the corporate income tax rate to 21% effective January 1, 2018, among others. The Company was required to recognize the effect of the tax law changes in the period of enactment, such as remeasuring its U.S. deferred tax assets and liabilities as well as reassessing the net realizability of its deferred tax assets and liabilities. As of December 31, 2017, the Company re-measured all deferred taxes at 21% and recorded a decrease related to the net deferred tax asset balance with a corresponding net adjustment to the Company's valuation allowance. As of December 31, 2018, the Company had completed its accounting under the Tax Act and no additional adjustments to its financial statements were recorded.

Facility Lease

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Facility lease

11. Facility Lease

In January 2015, the Company signed an initial operating lease, effective February 1, 2015 for 8,138 square feet of office and laboratory space with a one year term. Between January 2015 and October 2018, the Company entered into a series of lease amendments to increase the amount of leased space to 27,280 square feet and extend the expiration of the lease to February 2023. The lease agreement includes annual rent escalations. Under the lease and subsequent amendments, the landlord provided approximately $1.9 million in free rent and lease incentives. The Company records rent expense on a straight-line basis over the effective term of the lease, including any free rent periods and incentives. In calculating the present value of the lease payments, the Company has utilized its incremental borrowing rate. The Company’s facility lease is a net lease, as the non-lease components (i.e. common area maintenance) are paid separately from rent based on actual costs incurred. Therefore, the non-lease components were not included in the right-of-use asset and liability and are reflected as an expense in the period incurred.

As of June 30, 2019 and December 31, 2018, the right-of-use asset under operating lease was $2.6 million and $0, respectively. The elements of lease expense were as follows (in thousands):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Operating lease cost
Rent expense	$	233	$	167	$	481	$	344
Common area maintenance		81		73		162		149
Total operating lease cost	$	314	$	240	$	643	$	493
Other Information
Operating cash flows used for operating lease	$	370	$	343	$	729	$	699
Operating lease liabilities arising from obtaining right-of-use asset		—		—		3,580		—
Remaining lease term		3.6 years		2.6 years		3.6 years		2.6 years
Discount rate		10.0%		—		10.0%		—

As of June 30, 2019, minimum rental commitments under this lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2019*	$	563
2020		1,159
2021		1,260
2022		1,299
Total lease payments	$	4,281
Less: imputed interest		(701)
Total	$	3,580

* Remainder of the year

As of December 31, 2018, minimum rental commitments under this lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2019	$	1,110
2020		1,142
2021		1,251
2022		1,296
2023		109
Total	$	4,908

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2019
Commitments and Contingencies
Commitments and Contingencies	12. Commitments and Contingencies In August 2015, the Company entered into an agreement for a line of credit of $0.1 million for the purpose of issuing its landlord a letter of credit of $0.1 million as a security deposit under its facility lease. The Company pledged money market funds and marketable securities as collateral for the line of credit. For further discussion of the Company’s facility lease agreement, see Note 11. Pursuant to the Company’s license agreements with each of Vernalis and Scripps, it has obligations to make future milestone and royalty payments to these parties, respectively. However, because these amounts are contingent, they have not been included on the Company’s balance sheet. For further discussion of the Vernalis and Scripps licensing agreements, see Note 5. Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third‑party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company has also entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. There have been no claims to date and the Company has a directors and officers insurance policy that may enable it to recover a portion of any amounts paid for future claims. Legal Proceedings The Company is not a party to any material legal proceedings.

Related Party Transaction

6 Months Ended

Jun. 30, 2019

Related Party Transaction

Related Party Transaction

13. Related Party Transactions

In March 2018, the Company completed a follow-on public offering in which the Company sold 8,117,647 shares of common stock at a price of $8.50 per share, which included 1,058,823 shares issued pursuant to the underwriters’ exercise of their option to purchase additional shares of common stock. The aggregate net proceeds received by the Company from the offering were approximately $64.9 million, net of underwriting discounts and commissions and offering expenses payable by the Company.

The following aggregate number of shares of common stock were sold to our owners of more than 5% of our common stock, directors, or executive officers during the March 2018 underwritten public offering:


	March 2018 Public Offering
	Number of		Aggregate
		Shares of	Purchase
	Common Stock		Price
Owners of More Than 5% of Our Common Stock
FMR LLC		1,176,470	$	9,999,995
Orbimed Advisors LLC (1)		588,235		4,999,998
Novo Holdings A/S (2)		1,176,470		9,999,995
Adams Street Partners (3)		588,235		4,999,998
Board of Directors
Richard A. Miller, M.D.		100,000		850,000

(1)

Peter Thompson, M.D., a member of our Board of Directors since November 2014, is a Private Equity Partner for OrbiMed Advisors, LLC.

(2)

Peter Moldt, Ph.D., a Partner at Novo Ventures (US) Inc., which provide certain consultancy services to Novo Holdings A/S, served as a member of our Board of Directors from January 2015 to January 2019.

(3)

Elisha P. (Terry) Gould III, a member of our Board of Directors since November 2014, is a Partner at Adams Street Partners, LLC.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2019
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Company’s functional and reporting currency is the U.S. dollar. The accompanying condensed financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and discharge of liabilities in the normal course of business. Since its inception, the Company has incurred significant losses and negative cash flows from operations. As of June 30, 2019, the Company had an accumulated deficit of $195.1 million and cash, cash equivalents and marketable securities of $96.8 million. The Company has financed its operations primarily with the proceeds from the sale of stock. The Company will need to raise additional capital to meet its business objectives. The Company believes that its current cash, cash equivalents and marketable securities will be sufficient to fund its planned expenditures and meet its obligations through at least the next twelve months from the issuance of these financial statements.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying interim condensed financial statements and related disclosures are unaudited, have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the results of operations for the periods presented. The year-end condensed balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The condensed results of operations for the six months ended June 30, 2019 are not necessarily indicative of the results to be expected for the full year or for any other future year or interim period. The accompanying condensed financial statements should be read in conjunction with the audited financial statements and the related notes for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 7, 2019.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed financial statements and accompanying notes. Actual results could differ from such estimates.
Concentrations of Credit Risk and Other Risks and Uncertainties	Concentrations of Credit Risk and Other Risks and Uncertainties Substantially all of the Company’s cash and cash equivalents are deposited in accounts with two financial institutions that management believes are of high credit quality. Such deposits may, at times, exceed federally insured limits. The Company maintains its cash with an accredited financial institution and accordingly, such funds are subject to minimal credit risk. The Company’s marketable securities consist of investments in U.S. government agency securities and corporate debt obligations, which can be subject to certain credit risks. However, the Company mitigates the risks by investing in high-grade instruments, limiting its exposure to any one issuer, and monitoring the ongoing creditworthiness of the financial institutions and issuers. The Company has not experienced any losses on its deposits of cash, cash equivalents or marketable securities. The Company is subject to a number of risks similar to other early stage biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, its reliance on third parties to conduct its clinical trials, the need to obtain marketing approval for its product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, its right to develop and commercialize its product candidates pursuant to the terms and conditions of the licenses granted to the Company, and protection of proprietary technology. If the Company does not successfully commercialize or partner any of its product candidates, it will be unable to generate product revenue or achieve profitability.
Segments	Segments Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision‑maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment, that of the development of and commercialization of precisely targeted oncology therapies.
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 to its financial statements for the year ended December 31, 2018, included in its Annual Report on Form 10-K. Other than the adoption of ASU No. 2016-02, Leases (Topic 842) described below, there have been no material changes to the Company’s significant accounting policies during the six months ended June 30, 2019.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use (ROU) model that requires a lessee to recognize an ROU asset and lease liability on the balance sheet. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the statement of operations. The Company adopted the new standard on January 1, 2019 and has elected the ‘package of practical expedients’, which permit it not to reassess under the new standard its prior conclusions about lease identification, lease classification and initial direct costs. The Company did not elect the use-of-hindsight or the practical expedient pertaining to land easements; the latter is not applicable to the Company. See also Note 11.

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2019

Net Loss per Share

Schedule of net loss per share, basic and diluted


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Numerator:
Net loss - basic and diluted	$	(12,978)	$	(11,631)	$	(24,621)	$	(25,932)
Denominator:
Weighted average common shares outstanding		29,329,229		29,194,462		29,328,075		26,048,630
Less: weighted average common shares subject to repurchase		(20,079)		(214,948)		(26,570)		(263,087)
Weighted average common shares outstanding used to compute basic and diluted net loss per share		29,309,150		28,979,514		29,301,505		25,785,543
Net loss per share, basic and diluted	$	(0.44)	$	(0.40)	$	(0.84)	$	(1.01)

Schedule of antidilutive securities excluded from calculation of diluted net loss per share


	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2019	2018	2019	2018
Common stock subject to repurchase	12,384	172,955	12,384	172,955
Outstanding options	4,157,154	3,019,438	4,157,154	3,019,438
Total shares of common stock equivalents	4,169,538	3,192,393	4,169,538	3,192,393

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Measurements

Schedule of fair value of assets measured at fair value on a recurring basis, by level of fair value hierarchy


	June 30, 2019
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	29,679	$	—	$	—	$	29,679
Marketable securities		—		66,657		—		66,657
	$	29,679	$	66,657	$	—	$	96,336


	December 31, 2018
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	38,698	$	—	$	—	$	38,698
Marketable securities		—		75,401		—		75,401
	$	38,698	$	75,401	$	—	$	114,099

Schedule of fair value of available for sale marketable securities


	June 30, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Government agency securities	$	32,837	$	18	$	—	$	32,855
Corporate debt obligations		33,781		26		(5)		33,802
	$	66,618	$	44	$	(5)	$	66,657


	December 31, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Government agency securities	$	49,124	$	—	$	(27)	$	49,097
Corporate debt obligations		26,311		—		(7)		26,304
	$	75,435	$	—	$	(34)	$	75,401

Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2019

Balance Sheet Components

Schedule of balance sheet components


	June 30,		December 31,
	2019		2018
Prepaid and Other Current Assets
Interest receivable	$	253	$	337
Prepaid research and development manufacturing expenses		—		75
Prepaid facility expenses		152		149
Prepaid insurance		398		166
Other		502		265
	$	1,305	$	992
Property and Equipment
Laboratory equipment	$	2,388	$	2,371
Computer equipment and purchased software		142		142
Leasehold improvements		2,084		2,084
		4,614		4,597
Less: accumulated depreciation and amortization		(2,790)		(2,417)
	$	1,824	$	2,180
Accrued and Other Liabilities
Accrued clinical trial related	$	2,923	$	2,718
Accrued manufacturing expense		2,518		1,077
Personnel related		1,345		649
Deferred rent		—		160
Accrued legal and accounting		175		77
Other accrued expenses		283		348
	$	7,244	$	5,029
Other Liabilities
Deferred rent	$	—	$	869
	$	—	$	869

Common Stock (Tables)

6 Months Ended

Jun. 30, 2019

Common Stock

Schedule of shares of common stock reserved for issuance


	June 30,	December 31,
	2019	2018
Shares available for future option grants	3,253,272	2,486,637
Outstanding options	4,157,154	3,778,259
Unvested restricted common stock (founders and early exercise of stock options)	12,384	43,076
Shares reserved for employee stock purchase plan	400,000	400,000
Total	7,822,810	6,707,972

Stock Option Plans (Tables)

6 Months Ended

Jun. 30, 2019

Stock Option Plans

Summary of stock option activity


		Options Outstanding
			Weighted ‑
	Shares		Average
	Available	Number of	Exercise
	for Grant	Options	Price
Balance at December 31, 2018	2,486,637	3,778,259	$	10.32
Additional shares authorized	1,170,000	—		—
Options granted	(417,000)	417,000		3.87
Options exercised	—	(24,470)		0.28
Options forfeited	13,635	(13,635)		11.86
Balance at June 30, 2019	3,253,272	4,157,154	$	9.73

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Stock-Based Compensation

Schedule of expenses relating to employee and non-employee stock-based awards


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Research and development	$	800	$	785	$	1,598	$	1,545
General and administrative		1,098		951		2,253		1,991
Total	$	1,898	$	1,736	$	3,851	$	3,536

Facility Lease (Tables)

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Elements of lease expense


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Operating lease cost
Rent expense	$	233	$	167	$	481	$	344
Common area maintenance		81		73		162		149
Total operating lease cost	$	314	$	240	$	643	$	493
Other Information
Operating cash flows used for operating lease	$	370	$	343	$	729	$	699
Operating lease liabilities arising from obtaining right-of-use asset		—		—		3,580		—
Remaining lease term		3.6 years		2.6 years		3.6 years		2.6 years
Discount rate		10.0%		—		10.0%		—

Minimum rental commitments

As of June 30, 2019, minimum rental commitments under this lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2019*	$	563
2020		1,159
2021		1,260
2022		1,299
Total lease payments	$	4,281
Less: imputed interest		(701)
Total	$	3,580

* Remainder of the year

Schedule of future minimum lease payments under Topic 840

As of December 31, 2018, minimum rental commitments under this lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2019	$	1,110
2020		1,142
2021		1,251
2022		1,296
2023		109
Total	$	4,908

Related Party Transaction (Tables)

6 Months Ended

Jun. 30, 2019

Related Party Transaction

Schedule of common stock sold to related parties


	March 2018 Public Offering
	Number of		Aggregate
		Shares of	Purchase
	Common Stock		Price
Owners of More Than 5% of Our Common Stock
FMR LLC		1,176,470	$	9,999,995
Orbimed Advisors LLC (1)		588,235		4,999,998
Novo Holdings A/S (2)		1,176,470		9,999,995
Adams Street Partners (3)		588,235		4,999,998
Board of Directors
Richard A. Miller, M.D.		100,000		850,000

(1)

Peter Thompson, M.D., a member of our Board of Directors since November 2014, is a Private Equity Partner for OrbiMed Advisors, LLC.

(2)

(3)

Elisha P. (Terry) Gould III, a member of our Board of Directors since November 2014, is a Partner at Adams Street Partners, LLC.

Organization - Public Offerings (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	6 Months Ended
	Apr. 26, 2016	Mar. 29, 2016	Mar. 31, 2018	Jun. 30, 2018
Public Offerings
Proceeds from sale of stock				$ 64,877
IPO
Public Offerings
Shares Issued, Price Per Share		$ 15.00
Issuance of stock (in shares)		4,700,000
Net proceeds from IPO	$ 70,600
Over-Allotment Option
Public Offerings
Shares Issued, Price Per Share	$ 15.00
Issuance of stock (in shares)	502,618		1,058,823
FPO
Public Offerings
Shares Issued, Price Per Share			$ 8.50
Issuance of stock (in shares)			8,117,647
Proceeds from sale of stock			$ 64,900

Summary of Significant Accounting Policies - Basis of Presentation, Credit Risk and Income Taxes (Details) $ in Thousands		6 Months Ended
	Jan. 01, 2019	Jun. 30, 2019 USD ($) segment item	Dec. 31, 2018 USD ($)
Summary of Significant Accounting Policies
Accumulated deficit		$ (195,094)	$ (170,473)
Cash, cash equivalents and marketable securities		$ 96,800
Concentrations of Credit Risk and Other Risks and Uncertainties
Number of financial institutions used for cash and cash equivalent deposits \| item		2
Segments
Number of operating segments \| segment		1
Recent accounting pronouncements
Package of practical expedients adopted	true
Use of hindsight adopted	false

Net Loss per Share - Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net loss - basic and diluted	$ (12,978)	$ (11,643)	$ (11,631)	$ (14,301)	$ (24,621)	$ (25,932)
Denominator:
Weighted average common shares outstanding	29,329,229		29,194,462		29,328,075	26,048,630
Less: weighted average common shares subject to repurchase	(20,079)		(214,948)		(26,570)	(263,087)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	29,309,150		28,979,514		29,301,505	25,785,543
Net loss per share, basic and diluted (in dollars per share)	$ (0.44)		$ (0.40)		$ (0.84)	$ (1.01)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Loss per Share - Anti-Dilutive Securities (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect
Shares of common stock equivalents	4,169,538	3,192,393	4,169,538	3,192,393
Common stock subject to repurchase
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect
Shares of common stock equivalents	12,384	172,955	12,384	172,955
Outstanding options
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect
Shares of common stock equivalents	4,157,154	3,019,438	4,157,154	3,019,438

Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Transfer between levels
Transfer of assets from level 1 to 2	$ 0
Transfer of assets from level 2 to 1	0
Transfer of liabilities from level 1 to 2	0
Transfer of liabilities from level 2 to 1	0
Transfer of assets into level 3	0
Transfer of assets out of level 3	0
Transfer of liabilities into level 3	0
Transfer of liabilities out of level 3	$ 0
Assets
Maximum remaining maturity of marketable securities	11 months
Recurring
Assets
Cash equivalents	$ 29,679	$ 38,698
Marketable securities	66,657	75,401
Total Assets	96,336	114,099
Recurring \| Level 1
Assets
Cash equivalents	29,679	38,698
Total Assets	29,679	38,698
Recurring \| Level 2
Assets
Marketable securities	66,657	75,401
Total Assets	$ 66,657	$ 75,401

Fair Value Measurements - Available For Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair value of available for sale marketable securities
Amortized Cost	$ 66,618	$ 75,435
Gross Unrealized Gains	44
Gross Unrealized Losses	(5)	(34)
Fair Value	66,657	75,401
U.S. Government agency securities
Fair value of available for sale marketable securities
Amortized Cost	32,837	49,124
Gross Unrealized Gains	18
Gross Unrealized Losses		(27)
Fair Value	32,855	49,097
Corporate debt obligations
Fair value of available for sale marketable securities
Amortized Cost	33,781	26,311
Gross Unrealized Gains	26
Gross Unrealized Losses	(5)	(7)
Fair Value	$ 33,802	$ 26,304

License and Collaboration Agreements (Details) - Licensing Agreement - USD ($)	6 Months Ended
	Jun. 30, 2019	Feb. 28, 2017	Dec. 31, 2015	Feb. 28, 2015
Scripps Research Institute
License and Collaboration Agreements
Minimum annual fee			$ 25,000
Aggregate potential milestone payments	$ 2,600,000
Milestone payments made	$ 0
Period of written notice to terminate	90 days
Scripps Research Institute \| Research and development
License and Collaboration Agreements
One-time cash payment			$ 10,000
Vernalis (R&D) Limited
License and Collaboration Agreements
Milestone payments made		$ 3,000,000
Period of written notice to terminate	90 days
Vernalis (R&D) Limited \| Minimum
License and Collaboration Agreements
Aggregate potential milestone payments	$ 220,000,000
Vernalis (R&D) Limited \| Research and development
License and Collaboration Agreements
One-time cash payment				$ 1,000,000

Balance Sheet Components - Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Prepaid and Other Current Assets
Interest receivable	$ 253	$ 337
Prepaid research and development manufacturing expenses		75
Prepaid facility expenses	152	149
Prepaid insurance	398	166
Other	502	265
Total of prepaid and other current assets	$ 1,305	$ 992

Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property and Equipment
Property and equipment, gross	$ 4,614	$ 4,597
Less: accumulated depreciation and amortization	(2,790)	(2,417)
Property and equipment, net	1,824	2,180
Laboratory equipment
Property and Equipment
Property and equipment, gross	2,388	2,371
Computer equipment and purchased software
Property and Equipment
Property and equipment, gross	142	142
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 2,084	$ 2,084

Balance Sheet Components - Accrued and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accrued and Other Liabilities
Accrued clinical trial related	$ 2,923	$ 2,718
Accrued manufacturing expense	2,518	1,077
Personnel related	1,345	649
Deferred rent		160
Accrued legal and accounting	175	77
Other accrued expenses	283	348
Total of accrued and other liabilities	$ 7,244	$ 5,029

Balance Sheet Components - Other Liabilities (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Other Liabilities
Deferred rent	$ 869
Total of other liabilities	$ 869

Common Stock (Details)	1 Months Ended	6 Months Ended
Common Stock (Details)	Sep. 30, 2017 USD ($)	Jun. 30, 2019 USD ($) Vote shares	Jun. 30, 2018 USD ($)	Dec. 31, 2018 shares
Common Stock
Common stock, shares authorized for issuance		290,000,000		290,000,000
Preferred stock, shares authorized for issuance		10,000,000		10,000,000
Number of votes per share of common stock \| Vote		1
Dividends on common stock \| $		$ 0
Proceeds from sale of stock \| $			$ 64,877,000
Shares of common stock reserved for issuance, on an as-converted basis
Shares available for future option grants		3,253,272		2,486,637
Outstanding options		4,157,154		3,778,259
Unvested restricted common stock (founders and early exercise of stock options)		12,384		43,076
Shares reserved for employee stock purchase plan		400,000		400,000
Total		7,822,810		6,707,972
At-the-market offering \| Cowen
Common Stock
Proceeds from sale of stock \| $		$ 0
At-the-market offering \| Cowen \| Maximum
Common Stock
Potential gross proceeds \| $	$ 125,000,000
Stock issuance costs, as a percent of gross proceeds	3.00%

Stock Option Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended				6 Months Ended
	Mar. 31, 2016	Feb. 28, 2014	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019
Shares Available for Grant
Beginning balance				2,486,637			2,486,637
Exercised			$ 5	$ 1	$ 41	$ 7
Ending balance			3,253,272				3,253,272
Number of Options
Beginning balance				3,778,259			3,778,259
Ending balance			4,157,154				4,157,154
2014 Plan
Stock Option Plans
Vesting period		4 years
Maximum exercise term		10 years
Exercise price of common stock of its fair value (as a percent)		100.00%
Maximum number of options that may be re-issued under the 2016 plan	1,136,229
Shares Available for Grant
Ending balance	0
2016 Plan
Stock Option Plans
Vesting period	4 years
Maximum exercise term	10 years
Exercise price of common stock of its fair value (as a percent)	100.00%
Shares Available for Grant
Beginning balance				2,486,637			2,486,637
Additional shares authorized							1,170,000
Granted							(417,000)
Forfeited							13,635
Ending balance			3,253,272				3,253,272
Number of Options
Beginning balance				3,778,259			3,778,259
Granted							417,000
Exercised							(24,470)
Forfeited							(13,635)
Ending balance			4,157,154				4,157,154
Weighted-Average Exercise Price
Beginning balance (in dollars per share)				$ 10.32			$ 10.32
Granted (in dollars per share)							3.87
Exercised (in dollars per share)							0.28
Forfeited (in dollars per share)							11.86
Ending balance (in dollars per share)			$ 9.73				$ 9.73

Stock-Based Compensation - Expense Allocation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock-based compensation
Stock-based compensation expense	$ 1,898	$ 1,736	$ 3,851	$ 3,536
Research and development
Stock-based compensation
Stock-based compensation expense	800	785	1,598	1,545
General and administrative
Stock-based compensation
Stock-based compensation expense	$ 1,098	$ 951	$ 2,253	$ 1,991

Income Taxes - Tax Cut and Jobs Act (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Taxes
Income tax benefits		$ 0	$ 0	$ 0	$ 0
Effect of Tax Cuts and Jobs Act [Abstract]
Corporate income tax rate (as a percent)	21.00%

Facility Lease - Lessee information (Details) $ in Thousands	46 Months Ended
	Oct. 31, 2018 USD ($) ft²	Jun. 30, 2019 USD ($)	Jan. 31, 2015 ft²
Lessee Disclosure [Abstract]
Area of leased facility \| ft²	27,280		8,138
Lease term			1 year
Landlord Provided Free Rent And Lease Incentives	$ 1,900
Operating lease right-of-use asset		$ 2,634

Facility Lease - Lease cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating lease cost
Base rent expense	$ 233	$ 167	$ 481	$ 344
Common area maintenance	81	73	162	149
Total operating lease cost	314	240	643	493
Other Information
Operating cash flows used for operating lease	370	$ 343	729	$ 699
Operating lease liabilities arising from obtaining right-of-use asset	$ 3,580		$ 3,580
Remaining lease term	3 years 7 months 6 days	2 years 7 months 6 days	3 years 7 months 6 days	2 years 7 months 6 days
Discount rate	10.00%		10.00%

Facility Lease - Minimum rental commitments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Minimum rental commitments under Topic 842
2019*	$ 563
2020	1,159
2021	1,260
2022	1,299
Total lease payments	4,281
Less: imputed interest	(701)
Total	$ 3,580
Minimum rental commitments under Topic 840
2019		$ 1,110
2020		1,142
2021		1,251
2022		1,296
2023		109
Total		$ 4,908

Commitments and Contingencies - Line of Credit (Details) $ in Millions	Aug. 31, 2015 USD ($)
Line of credit
Security deposit	$ 0.1
Secured debt
Line of credit
Line of credit	$ 0.1

Related Party Transaction (Details) - USD ($)			1 Months Ended	6 Months Ended
Related Party Transaction (Details) - USD ($)	Apr. 26, 2016	Mar. 29, 2016	Mar. 31, 2018	Jun. 30, 2018
Public Offerings
Proceeds from sale of stock				$ 64,877,000
FMR LLC
Public Offerings
Number of Share of Common Stock issued			1,176,470
Owners of More Than 5% of Our Common Stock or Board of Directors
Aggregate Purchase Price			$ 9,999,995
Orbimed Advisors LLC
Public Offerings
Number of Share of Common Stock issued			588,235
Owners of More Than 5% of Our Common Stock or Board of Directors
Aggregate Purchase Price			$ 4,999,998
Novo Holdings A/S
Public Offerings
Number of Share of Common Stock issued			1,176,470
Owners of More Than 5% of Our Common Stock or Board of Directors
Aggregate Purchase Price			$ 9,999,995
Adams Street Partners
Public Offerings
Number of Share of Common Stock issued			588,235
Owners of More Than 5% of Our Common Stock or Board of Directors
Aggregate Purchase Price			$ 4,999,998
Director
Public Offerings
Number of Share of Common Stock issued			100,000
Owners of More Than 5% of Our Common Stock or Board of Directors
Aggregate Purchase Price			$ 850,000
IPO
Public Offerings
Share offering price		$ 15.00
Number of Share of Common Stock issued		4,700,000
Net proceeds from IPO	$ 70,600,000
Over-Allotment Option
Public Offerings
Share offering price	$ 15.00
Number of Share of Common Stock issued	502,618		1,058,823

CONSOLIDATED STATEMENTS OF CASH FLOW (Parenthetical) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
CONSOLIDATED STATEMENTS OF CASH FLOWS
Proceeds from issuance of common stock, net, from related parties	$ 30,850