Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Aug. 02, 2018
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, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		29,197,857
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 28,068	$ 45,106
Marketable securities	105,157	44,949
Prepaid and other current assets	1,208	1,179
Total current assets	134,433	91,234
Property and equipment, net	2,293	2,672
Other assets	1,193	869
Total assets	137,919	94,775
Current liabilities:
Accounts payable	2,255	3,454
Accrued and other liabilities	7,524	5,515
Total current liabilities	9,779	8,969
Other liabilities	741	971
Total liabilities	10,520	9,940
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock: $0.0001 par value; 10,000,000 shares authorized at June 30, 2018 and December 31, 2017; 00 shares issued and outstanding at June 30, 2018 and December 31, 2017
Common stock: $0.0001 par value; 290,000,000 shares authorized at June 30, 2018 and December 31, 2017; 29,197,857 and 21,041,250 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	3	2
Additional paid-in capital	276,882	208,408
Accumulated other comprehensive loss	(20)	(41)
Accumulated deficit	(149,466)	(123,534)
Total stockholders' equity	127,399	84,835
Total liabilities and stockholders' equity	$ 137,919	$ 94,775

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
CONDENSED 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	29,197,857	21,041,250
Common stock, shares outstanding	29,197,857	21,041,250

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating expenses:
Research and development	$ 9,715	$ 12,386	$ 21,818	$ 25,884
General and administrative	2,543	2,788	5,084	5,507
Total operating expenses	12,258	15,174	26,902	31,391
Loss from operations	(12,258)	(15,174)	(26,902)	(31,391)
Interest income and other expense, net	627	193	970	374
Net loss	$ (11,631)	$ (14,981)	$ (25,932)	$ (31,017)
Net loss per share, basic and diluted (in dollars per share)	$ (0.40)	$ (0.73)	$ (1.01)	$ (1.52)
Shares used to compute net loss per share, basic and diluted (in shares)	28,979,514	20,426,849	25,785,543	20,388,820
Other comprehensive income (loss):
Unrealized loss on marketable securities	$ 19	$ 11	$ 21	$ (13)
Comprehensive loss	$ (11,612)	$ (14,970)	$ (25,911)	$ (31,030)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (25,932)	$ (31,017)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	439	412
Accretion related to marketable securities	(232)	(113)
Stock-based compensation	3,536	2,989
Changes in operating assets and liabilities:
Prepaid and other current assets	(9)	(184)
Other assets	(323)
Accounts payable	(1,199)	2,322
Accrued and other liabilities	2,015	1,350
Other long-term liabilities	(229)	(218)
Net cash used in operating activities	(21,934)	(24,459)
Cash flows from investing activities
Purchases of marketable securities	(99,455)	(47,072)
Maturities of marketable securities	39,479	100,800
Purchase of property and equipment	(60)	(232)
Net cash provided by (used in) investing activities	(60,036)	53,496
Cash flows from financing activities
Proceeds from issuance of common stock, net	64,877
Proceeds from exercise of common stock options	55	8
Net cash provided by financing activities	64,932	8
Net increase (decrease) in cash and cash equivalents	(17,038)	29,045
Cash and cash equivalents at beginning of the period	45,106	5,050
Cash and cash equivalents at end of the period	$ 28,068	$ 34,095

Organization	6 Months Ended
Organization	Jun. 30, 2018
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. The Company has four insignificant subsidiaries. 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, after underwriting discounts, commissions and offering expenses. 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, 2018
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Company’s functional and reporting currency is the U.S. dollar. The accompanying condensed consolidated 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. During the six months ended June 30, 2018, the Company incurred a net loss of $25.9 million and used $21.9 million of cash in operations. As of June 30, 2018, the Company had an accumulated deficit of $149.5 million and cash, cash equivalents and marketable securities of $133.2 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 consolidated 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 consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The condensed consolidated results of operations for the three and six months ended June 30, 2018 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 consolidated financial statements should be read in conjunction with the audited financial statements and the related notes for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2018. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated 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 oncology therapies. Critical Accounting Policies The Company’s critical accounting policies are described in Note 2 to our consolidated financial statements for the year ended December 31, 2017, included in our Annual Report on Form 10-K. There have been no material changes to the Company’s critical accounting policies during the six months ended June 30, 2018. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014‑09, Revenue from Contracts with Customers, which required an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU No. 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it became effective on January 1, 2018 for public companies. The standard permits the use of either the retrospective or cumulative effect transition method. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which clarifies the implementation guidance on principal versus agent considerations in ASU No. 2014-09. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which relates to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration and the presentation of sales and other similar taxes collected from customers. These standards have the same effective date and transition date of January 1, 2018. The Company adopted this guidance on January 1, 2018. The adoption of this guidance did not have a material impact on its condensed consolidated financial statements as the Company is not yet generating revenues. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) that replaces existing lease guidance. The new standard requires lessees to record right of use assets and corresponding lease liabilities on the balance sheet. The new guidance will continue to classify leases as either finance or operating, with classification affecting the pattern of expense recognition in the statement of income. Further in 2018, the FASB provided an optional transition and practical expedient to not evaluate under the new guidance existing or expired land easements that were not previously accounted for as leases under the current guidance. The standard is effective for the Company beginning January 1, 2019, with early application permitted. The Company is currently assessing the impact of this guidance on its condensed consolidated financial statements.

Net Loss per Share

6 Months Ended

Jun. 30, 2018

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,
	2018		2017		2018		2017
Numerator:
Net loss - basic and diluted	$	(11,631)	$	(14,981)	$	(25,932)	$	(31,017)
Denominator:
Weighted average common shares outstanding		29,194,462		20,934,514		26,048,630		20,931,765
Less: weighted average common shares subject to repurchase		(214,948)		(507,665)		(263,087)		(542,945)
Weighted average common shares outstanding used to compute basic and diluted net loss per share		28,979,514		20,426,849		25,785,543		20,388,820
Net loss per share, basic and diluted	$	(0.40)	$	(0.73)	$	(1.01)	$	(1.52)

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,
	2018	2017	2018	2017
Common stock subject to repurchase	172,955	465,451	172,955	465,451
Outstanding options	3,019,438	2,441,856	3,019,438	2,441,856
Total shares of common stock equivalents	3,192,393	2,907,307	3,192,393	2,907,307

Fair Value Measurements

6 Months Ended

Jun. 30, 2018

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, 2018 and December 31, 2017 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, 2018
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	—	$	27,486	$	—	$	27,486
Marketable securities		—		105,157		—		105,157
	$	—	$	132,643	$	—	$	132,643


	December 31, 2017
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	–	$	44,555	$	—	$	44,555
Marketable securities		–		44,949		—		44,949
	$	–	$	89,504	$	—	$	89,504

As of June 30, 2018, marketable securities had a maximum remaining maturity of twelve months.

As of June 30, 2018 and December 31, 2017, the fair value of available for sale marketable securities by type of security were as follows (in thousands):


	June 30, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Government agency securities	$	78,747	$	—	$	(20)	$	78,727
Corporate debt obligations		26,430		—		—		26,430
	$	105,177	$	—	$	(20)	$	105,157


	December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Government agency securities	$	32,311	$	—	$	(39)	$	32,272
Corporate debt obligations		12,679		—		(2)		12,677
	$	44,990	$	—	$	(41)	$	44,949

- 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, 2018
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. 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. The first minimum annual fee payment was due on the first anniversary of the effective date of the agreement and will be due on each subsequent anniversary of the effective date 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 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 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 CPI-444 in the Company’s Phase 1/1b clinical trial. The aggregate potential milestone payments exceed $200 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 CPI‑444 on a product‑by‑product and country‑by‑country basis, subject to certain offsets and reductions. The tiered royalty rates for products containing CPI‑444 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 CPI‑444 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 CPI-444 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 CPI-444 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 CPI-444. 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 CPI-444 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 this second agreement, CPI-444 administered in combination with Tecentriq (atezolizumab) will be evaluated in a Phase 1b/2 randomized, controlled clinical study 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. It is anticipated that the study will enroll up to 65 patients in the treatment arm. Genentech will be responsible for the conduct of the study and the parties will share the cost of the Phase 1b/2 trial, which began enrolling patients in the fourth quarter of 2017. The Company is responsible for supplying CPI-444 and retains global development and commercialization rights to CPI-444. 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 CPI-444 or Tecentriq is discontinued.

Balance Sheet Components

6 Months Ended

Jun. 30, 2018

Balance Sheet Components

Balance Sheet Components

6. Balance Sheet Components (in thousands)


	June 30,		December 31,
	2018		2017
Prepaid and Other Current Assets
Interest receivable	$	294	$	132
Prepaid research and development manufacturing expenses		67		327
Prepaid insurance		333		164
Other		514		556
	$	1,208	$	1,179
Property and Equipment
Laboratory equipment	$	2,092	$	2,034
Computer equipment and purchased software		129		130
Leasehold improvements		2,082		2,078
		4,303		4,242
Less: accumulated depreciation and amortization		(2,010)		(1,570)
	$	2,293	$	2,672
Accrued and Other Liabilities
Accrued clinical trial related	$	2,992	$	2,870
Accrued manufacturing expense		3,026		1,056
Personnel related		696		572
Deferred rent		427		410
Accrued legal and accounting		118		224
Other accrued expenses		265		383
	$	7,524	$	5,515
Other Liabilities
Deferred rent	$	738	$	960
Shares subject to vesting		3		11
	$	741	$	971

Common Stock

6 Months Ended

Jun. 30, 2018

Common Stock

Common Stock

7. Common Stock

As of June 30, 2018, 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, 2018, 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, 2018, 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,
	2018	2017
Shares available for future option grants	3,371,531	2,576,535
Outstanding options	3,019,438	3,013,394
Unvested restricted common stock (founders and early exercise of stock options)	172,955	319,203
Shares reserved for employee stock purchase plan	400,000	400,000
Total	6,963,924	6,309,132

Stock Option Plans

6 Months Ended

Jun. 30, 2018

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, 2017	2,576,535	3,013,394	$	11.78
Additional shares authorized	840,000	—		—
Options granted	(353,500)	353,500		10.93
Options exercised	—	(38,960)		1.23
Options forfeited	308,496	(308,496)		14.04
Balance at June 30, 2018	3,371,531	3,019,438	$	11.58

Stock-Based Compensation

6 Months Ended

Jun. 30, 2018

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,
	2018		2017		2018		2017
Research and development	$	785	$	642	$	1,545	$	1,265
General and administrative		951		879		1,991		1,724
Total	$	1,736	$	1,521	$	3,536	$	2,989

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2018
Income Taxes
Income Taxes	10. Income Taxes During the three and six months ended June 30, 2018 and 2017, 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 us, including a one-time mandatory transition tax on accumulated foreign earnings and 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 determining the transition tax, remeasuring its U.S. deferred tax assets and liabilities as well as reassessing the net realizability of its deferred tax assets and liabilities. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), which allows the Company to record provisional amounts to the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate during a measurement period not to extend beyond one year of the enactment date. The Company have not made any additional measurement-period adjustments related to Global Intangible Low-Taxed Income (“GILTI”) and have not yet made a policy decision regarding whether to record deferred taxes on GILTI during the three and six months ended June 30, 2018. However, the Company is continuing to gather additional information to complete its accounting for GILTI and expect to complete its accounting within the prescribed measurement period in accordance with SAB 118.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2018

Commitments and Contingencies

Commitments and Contingencies

11. Commitments and Contingencies

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 April 2018, the Company entered into a series of lease amendments to increase the amount of leased space to 27,100 square feet and extend the expiration of the lease to February 2021. The lease agreement includes an annual rent escalation clause and a right to extend the term at the then current market rate for three years. 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. The lease requires the Company to pay additional amounts for operating and maintenance expenses. Rent expense related to the facilities lease for the three and six months ended June 30, 2018 was approximately $167,000 and $344,000, respectively. Rent expense for the three and six months ended June 30, 2017 was approximately $184,000 and $367,000, respectively.

As of June 30, 2018, future minimum lease payments under the facility lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2018*	$	537
2019		1,103
2020		1,135
2021		95
Total	$	2,870

* Remainder of the year

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.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2018
Summary of Significant Accounting Policies
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 (“U.S. GAAP”). The Company’s functional and reporting currency is the U.S. dollar. The accompanying condensed consolidated 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. During the six months ended June 30, 2018, the Company incurred a net loss of $25.9 million and used $21.9 million of cash in operations. As of June 30, 2018, the Company had an accumulated deficit of $149.5 million and cash, cash equivalents and marketable securities of $133.2 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 consolidated 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 consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The condensed consolidated results of operations for the three and six months ended June 30, 2018 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 consolidated financial statements should be read in conjunction with the audited financial statements and the related notes for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2018.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated 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 oncology therapies.
Critical Accounting Policies	Critical Accounting Policies The Company’s critical accounting policies are described in Note 2 to our consolidated financial statements for the year ended December 31, 2017, included in our Annual Report on Form 10-K. There have been no material changes to the Company’s critical accounting policies during the six months ended June 30, 2018.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014‑09, Revenue from Contracts with Customers, which required an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU No. 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it became effective on January 1, 2018 for public companies. The standard permits the use of either the retrospective or cumulative effect transition method. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which clarifies the implementation guidance on principal versus agent considerations in ASU No. 2014-09. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which relates to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration and the presentation of sales and other similar taxes collected from customers. These standards have the same effective date and transition date of January 1, 2018. The Company adopted this guidance on January 1, 2018. The adoption of this guidance did not have a material impact on its condensed consolidated financial statements as the Company is not yet generating revenues. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) that replaces existing lease guidance. The new standard requires lessees to record right of use assets and corresponding lease liabilities on the balance sheet. The new guidance will continue to classify leases as either finance or operating, with classification affecting the pattern of expense recognition in the statement of income. Further in 2018, the FASB provided an optional transition and practical expedient to not evaluate under the new guidance existing or expired land easements that were not previously accounted for as leases under the current guidance. The standard is effective for the Company beginning January 1, 2019, with early application permitted. The Company is currently assessing the impact of this guidance on its condensed consolidated financial statements.

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2018

Net Loss per Share

Schedule of net loss per share, basic and diluted


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2018		2017		2018		2017
Numerator:
Net loss - basic and diluted	$	(11,631)	$	(14,981)	$	(25,932)	$	(31,017)
Denominator:
Weighted average common shares outstanding		29,194,462		20,934,514		26,048,630		20,931,765
Less: weighted average common shares subject to repurchase		(214,948)		(507,665)		(263,087)		(542,945)
Weighted average common shares outstanding used to compute basic and diluted net loss per share		28,979,514		20,426,849		25,785,543		20,388,820
Net loss per share, basic and diluted	$	(0.40)	$	(0.73)	$	(1.01)	$	(1.52)

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


	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2018	2017	2018	2017
Common stock subject to repurchase	172,955	465,451	172,955	465,451
Outstanding options	3,019,438	2,441,856	3,019,438	2,441,856
Total shares of common stock equivalents	3,192,393	2,907,307	3,192,393	2,907,307

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Measurements

Schedule of fair value of assets and liabilities recorded at fair value on a recurring basis, by level within fair value hierarchy


	June 30, 2018
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	—	$	27,486	$	—	$	27,486
Marketable securities		—		105,157		—		105,157
	$	—	$	132,643	$	—	$	132,643


	December 31, 2017
	Fair Value Measured Using						Total
	(Level 1)		(Level 2)		(Level 3)		Balance
Assets
Cash equivalents	$	–	$	44,555	$	—	$	44,555
Marketable securities		–		44,949		—		44,949
	$	–	$	89,504	$	—	$	89,504

Schedule of fair value of available for sale marketable securities

As of June 30, 2018 and December 31, 2017, the fair value of available for sale marketable securities by type of security were as follows (in thousands):


	June 30, 2018
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Government agency securities	$	78,747	$	—	$	(20)	$	78,727
Corporate debt obligations		26,430		—		—		26,430
	$	105,177	$	—	$	(20)	$	105,157


	December 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Government agency securities	$	32,311	$	—	$	(39)	$	32,272
Corporate debt obligations		12,679		—		(2)		12,677
	$	44,990	$	—	$	(41)	$	44,949

Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2018

Balance Sheet Components

Schedule of balance sheet components


	June 30,		December 31,
	2018		2017
Prepaid and Other Current Assets
Interest receivable	$	294	$	132
Prepaid research and development manufacturing expenses		67		327
Prepaid insurance		333		164
Other		514		556
	$	1,208	$	1,179
Property and Equipment
Laboratory equipment	$	2,092	$	2,034
Computer equipment and purchased software		129		130
Leasehold improvements		2,082		2,078
		4,303		4,242
Less: accumulated depreciation and amortization		(2,010)		(1,570)
	$	2,293	$	2,672
Accrued and Other Liabilities
Accrued clinical trial related	$	2,992	$	2,870
Accrued manufacturing expense		3,026		1,056
Personnel related		696		572
Deferred rent		427		410
Accrued legal and accounting		118		224
Other accrued expenses		265		383
	$	7,524	$	5,515
Other Liabilities
Deferred rent	$	738	$	960
Shares subject to vesting		3		11
	$	741	$	971

Common Stock (Tables)

6 Months Ended

Jun. 30, 2018

Common Stock

Schedule of shares of common stock reserved for issuance


	June 30,	December 31,
	2018	2017
Shares available for future option grants	3,371,531	2,576,535
Outstanding options	3,019,438	3,013,394
Unvested restricted common stock (founders and early exercise of stock options)	172,955	319,203
Shares reserved for employee stock purchase plan	400,000	400,000
Total	6,963,924	6,309,132

Stock Option Plans (Tables)

6 Months Ended

Jun. 30, 2018

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, 2017	2,576,535	3,013,394	$	11.78
Additional shares authorized	840,000	—		—
Options granted	(353,500)	353,500		10.93
Options exercised	—	(38,960)		1.23
Options forfeited	308,496	(308,496)		14.04
Balance at June 30, 2018	3,371,531	3,019,438	$	11.58

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Stock-Based Compensation

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

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,
	2018		2017		2018		2017
Research and development	$	785	$	642	$	1,545	$	1,265
General and administrative		951		879		1,991		1,724
Total	$	1,736	$	1,521	$	3,536	$	2,989

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2018

Commitments and Contingencies

Schedule of future minimum lease payments under the facility lease

As of June 30, 2018, future minimum lease payments under the facility lease were as follows (in thousands):


Year Ended December 31 (in thousands)
2018*	$	537
2019		1,103
2020		1,135
2021		95
Total	$	2,870

* Remainder of the year

Organization - Public Offerings (Details) $ / shares in Units, $ in Thousands			1 Months Ended	6 Months Ended
	Apr. 26, 2016 USD ($) $ / shares shares	Mar. 29, 2016 $ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) subsidiary
Initial Public Offering
Number of insignificant subsidiaries \| subsidiary				4
Proceeds from sale of stock \| $				$ 64,877
IPO
Initial Public Offering
Share Price \| $ / shares		$ 15.00
Issuance of stock (in shares) \| shares		4,700,000
Net proceeds from IPO \| $	$ 70,600
Over-Allotment Option
Initial Public Offering
Share Price \| $ / shares	$ 15.00
Issuance of stock (in shares) \| shares	502,618		1,058,823
FPO
Initial Public Offering
Share Price \| $ / shares			$ 8.50
Issuance of stock (in shares) \| 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	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment item	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Summary of Significant Accounting Policies
Net loss	$ (11,631)	$ (14,981)	$ (25,932)	$ (31,017)
Cash in operations			(21,934)	$ (24,459)
Accumulated deficit	(149,466)		(149,466)		$ (123,534)
Cash, cash equivalents and marketable securities	$ 133,200		$ 133,200
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

Net Loss per Share - Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net loss - basic and diluted	$ (11,631)	$ (14,981)	$ (25,932)	$ (31,017)
Denominator:
Weighted average common shares outstanding	29,194,462	20,934,514	26,048,630	20,931,765
Less: weighted average common shares subject to repurchase	(214,948)	(507,665)	(263,087)	(542,945)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	28,979,514	20,426,849	25,785,543	20,388,820
Net loss per share, basic and diluted (in dollars per share)	$ (0.40)	$ (0.73)	$ (1.01)	$ (1.52)

Net Loss per Share - Anti-Dilutive Securities (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect
Shares of common stock equivalents	3,192,393	2,907,307	3,192,393	2,907,307
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	172,955	465,451	172,955	465,451
Outstanding options
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect
Shares of common stock equivalents	3,019,438	2,441,856	3,019,438	2,441,856

Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
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
Assets
Maximum remaining maturity of marketable securities	12 months
Recurring
Assets
Cash equivalents	$ 27,486		$ 44,555
Marketable securities	105,157		44,949
Total Assets	132,643		89,504
Recurring \| Level 2
Assets
Cash equivalents	27,486		44,555
Marketable securities	105,157		44,949
Total Assets	$ 132,643		$ 89,504

Fair Value Measurements - Available For Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair value of available for sale marketable securities
Amortized Cost	$ 105,177	$ 44,990
Gross Unrealized Losses	(20)	(41)
Fair Value	105,157	44,949
Government agency securities
Fair value of available for sale marketable securities
Amortized Cost	78,747	32,311
Gross Unrealized Losses	(20)	(39)
Fair Value	78,727	32,272
Corporate debt obligations
Fair value of available for sale marketable securities
Amortized Cost	26,430	12,679
Gross Unrealized Losses		(2)
Fair Value	$ 26,430	$ 12,677

License and Collaboration Agreements (Details)	1 Months Ended	6 Months Ended
License and Collaboration Agreements (Details)	May 31, 2017 item	Jun. 30, 2018 USD ($)	Feb. 28, 2017 USD ($)	Dec. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)
Licensing Agreement \| 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
Licensing Agreement \| Scripps Research Institute \| Research and development
License and Collaboration Agreements
One-time cash payment				$ 10,000
Licensing Agreement \| Vernalis (R&D) Limited
License and Collaboration Agreements
Milestone payments made			$ 3,000,000
Period of written notice to terminate		90 days
Licensing Agreement \| Vernalis (R&D) Limited \| Minimum
License and Collaboration Agreements
Aggregate potential milestone payments		$ 200,000,000
Licensing Agreement \| Vernalis (R&D) Limited \| Research and development
License and Collaboration Agreements
One-time cash payment					$ 1,000,000
Clinical Trial Collaboration Agreement \| Genentech
License and Collaboration Agreements
Maximum number of patients in treatment arm under collaboration agreement \| item	65

Balance Sheet Components - Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Prepaid and Other Current Assets
Interest receivable	$ 294	$ 132
Prepaid research and development manufacturing expenses	67	327
Prepaid insurance	333	164
Other	514	556
Total of prepaid and other current assets	$ 1,208	$ 1,179

Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property and Equipment
Property and equipment, gross	$ 4,303	$ 4,242
Less: accumulated depreciation and amortization	(2,010)	(1,570)
Property and equipment, net	2,293	2,672
Laboratory equipment
Property and Equipment
Property and equipment, gross	2,092	2,034
Computer equipment and purchased software
Property and Equipment
Property and equipment, gross	129	130
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 2,082	$ 2,078

Balance Sheet Components - Accrued and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accrued and Other Liabilities
Accrued clinical trial related	$ 2,992	$ 2,870
Accrued manufacturing expense	3,026	1,056
Personnel related	696	572
Deferred rent	427	410
Accrued legal and accounting	118	224
Other accrued expenses	265	383
Total of accrued and other liabilities	$ 7,524	$ 5,515

Balance Sheet Components - Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other Liabilities
Deferred rent	$ 738	$ 960
Shares subject to vesting	3	11
Total of other liabilities	$ 741	$ 971

Common Stock (Details)	1 Months Ended	6 Months Ended
Common Stock (Details)	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Vote shares	Dec. 31, 2017 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		3,371,531	2,576,535
Outstanding options		3,019,438	3,013,394
Unvested restricted common stock (founders and early exercise of stock options)		172,955	319,203
Shares reserved for employee stock purchase plan		400,000	400,000
Total		6,963,924	6,309,132
Sales Agreement \| Cowen
Common Stock
Proceeds from sale of stock \| $		$ 0
Sales Agreement \| 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) - $ / shares	1 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2016	Feb. 28, 2014	Jun. 30, 2018	Dec. 31, 2017
Shares Available for Grant
Beginning balance			2,576,535
Additional shares authorized				840,000
Granted			(353,500)
Forfeited			308,496
Ending balance			3,371,531	2,576,535
Number of Options
Beginning balance			3,013,394
Granted			353,500
Exercised			(38,960)
Forfeited			(308,496)
Ending balance			3,019,438	3,013,394
Weighted-Average Exercise Price
Beginning balance (in dollars per share)			$ 11.78
Granted (in dollars per share)			10.93
Exercised (in dollars per share)			1.23
Forfeited (in dollars per share)			14.04
Ending balance (in dollars per share)			$ 11.58	$ 11.78
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
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%

Stock-Based Compensation - Expense Allocation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock-based compensation
Stock-based compensation expense	$ 1,736	$ 1,521	$ 3,536	$ 2,989
Research and development
Stock-based compensation
Stock-based compensation expense	785	642	1,545	1,265
General and administrative
Stock-based compensation
Stock-based compensation expense	$ 951	$ 879	$ 1,991	$ 1,724

Income Taxes (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Taxes
Income tax benefits		$ 0	$ 0	$ 0	$ 0
Corporate income tax rate (as a percent)	21.00%

Commitments and Contingencies (Details)	1 Months Ended	3 Months Ended		6 Months Ended		40 Months Ended
Commitments and Contingencies (Details)	Jan. 31, 2015 ft²	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Apr. 30, 2018 ft²	Mar. 31, 2018 ft²	Dec. 31, 2017 ft²
Facility Lease
Landlord Provided Free Rent And Lease Incentives		$ 1,900,000		$ 1,900,000
Rent expense		167,000	$ 184,000	344,000	$ 367,000
Future minimum lease payments
2018		537,000		537,000
2019		1,103,000		1,103,000
2020		1,135,000		1,135,000
2021		95,000		95,000
Total		$ 2,870,000		$ 2,870,000
Facilities lease
Facility Lease
Area of leased facility \| ft²	8,138					27,100	27,100	27,100
Lease term	1 year
Lease extension period						3 years