Chinook Therapeutics (KDNY) 10-Q 1 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 29, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	ADRO
Entity Registrant Name	ADURO BIOTECH, INC.
Entity Central Index Key	0001435049
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		80,140,274
Entity Current Reporting Status	Yes
Entity File Number	001-37345
Entity Tax Identification Number	943348934
Entity Address, Address Line One	740 Heinz Avenue
Entity Address, City or Town	Berkeley
Entity Address, State or Province	California
Entity Address Postal Zip Code	94710
City Area Code	(510)
Local Phone Number	848-4400

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 79,561	$ 126,310
Short-term marketable securities	172,072	140,129
Accounts receivable	1,363	12,037
Prepaid expenses and other current assets	3,779	4,500
Total current assets	256,775	282,976
Long-term marketable securities		11,434
Property and equipment, net	26,177	29,157
Operating lease right-of-use assets	21,609
Goodwill	8,277	8,334
Intangible assets, net	24,684	25,135
Restricted cash	468	468
Total assets	337,990	357,504
Current liabilities:
Accounts payable	1,000	1,457
Accrued clinical trial and manufacturing expenses	3,894	2,542
Accrued expenses and other liabilities	7,881	10,518
Operating lease liabilities	1,630
Deferred revenue	16,000	16,000
Total current liabilities	30,405	30,517
Deferred rent		11,063
Contingent consideration	1,015	998
Deferred revenue	165,908	172,671
Deferred tax liabilities	5,992	6,104
Operating lease liabilities	32,599
Other long-term liabilities	1,021	840
Total liabilities	236,940	222,193
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock, $0.0001 par value; 300,000,000 shares authorized; 80,130,274 and 79,571,714 shares issued and outstanding at June 30, 2019 and December 31, 2018	8	8
Additional paid-in capital	546,537	538,895
Accumulated other comprehensive income	1,042	940
Accumulated deficit	(446,537)	(404,532)
Total stockholders’ equity	101,050	135,311
Total liabilities and stockholders’ equity	$ 337,990	$ 357,504

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock par value 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 per share	$ 0.0001	$ 0.0001
Common stock shares authorized	300,000,000	300,000,000
Common stock shares issued	80,130,274	79,571,714
Common stock shares outstanding	80,130,274	79,571,714

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Total revenue	$ 4,888,000	$ 2,639,000	$ 8,826,000	$ 9,266,000
Operating expenses:
Research and development	16,876,000	19,420,000	36,406,000	39,547,000
General and administrative	7,980,000	8,827,000	17,162,000	17,872,000
Amortization of intangible assets	139,000	147,000	279,000	299,000
Total operating expenses	24,995,000	28,394,000	53,847,000	57,718,000
Loss from operations	(20,107,000)	(25,755,000)	(45,021,000)	(48,452,000)
Interest income	1,497,000	1,340,000	2,968,000	2,539,000
Other loss, net	(3,000)	(20,000)	(22,000)	(36,000)
Loss before income tax	(18,613,000)	(24,435,000)	(42,075,000)	(45,949,000)
Income tax benefit	35,000	38,000	70,000	59,000
Net loss	$ (18,578,000)	$ (24,397,000)	$ (42,005,000)	$ (45,890,000)
Net loss per common share, basic and diluted	$ (0.23)	$ (0.31)	$ (0.53)	$ (0.59)
Shares used in computing net loss per common share, basic and diluted	80,032,022	78,817,840	79,847,960	78,364,914
Collaboration and license revenue
Revenue:
Total revenue	$ 4,888,000	$ 2,639,000	$ 8,826,000	$ 9,266,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (18,578)	$ (24,397)	$ (42,005)	$ (45,890)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	147	53	331	(96)
Foreign currency translation adjustments	404	(1,495)	(229)	(618)
Comprehensive loss	$ (18,027)	$ (25,839)	$ (41,903)	$ (46,604)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance at Dec. 31, 2017	$ 237,473	$ 8	$ 519,435	$ 1,893	$ (283,863)
Beginning balance, Shares at Dec. 31, 2017		77,736,201
Issuance of common stock upon exercise of stock options	638		638
Issuance of common stock upon exercise of stock options, Shares		712,973
Issuance of common stock upon exercise of warrants, Shares		3,317
Release of restricted stock units		26,175
Stock-based compensation	4,924		4,924
Other comprehensive income (loss)	728			728
Cumulative effect of changes in accounting principles related to revenue recognition	(25,312)				(25,312)
Other	2				2
Net loss	(21,494)				(21,494)
Ending balance at Mar. 31, 2018	196,959	$ 8	524,997	2,621	(330,667)
Ending balance, Shares at Mar. 31, 2018		78,478,666
Beginning balance at Dec. 31, 2017	237,473	$ 8	519,435	1,893	(283,863)
Beginning balance, Shares at Dec. 31, 2017		77,736,201
Unrealized gain/loss on investments	(96)
Cumulative change in translation adjustment	(618)
Net loss	(45,890)
Ending balance at Jun. 30, 2018	176,434	$ 8	530,312	1,179	(355,065)
Ending balance, Shares at Jun. 30, 2018		79,059,764
Beginning balance at Mar. 31, 2018	196,959	$ 8	524,997	2,621	(330,667)
Beginning balance, Shares at Mar. 31, 2018		78,478,666
Issuance of common stock upon exercise of stock options	622		622
Issuance of common stock upon exercise of stock options, Shares		528,320
Issuance of common stock under Employee Stock Purchase Plan	366		366
Issuance of common stock under Employee Stock Purchase Plan, Shares		52,778
Stock-based compensation	4,327		4,327
Other comprehensive income (loss)	(1,442)			(1,442)
Unrealized gain/loss on investments	53
Cumulative change in translation adjustment	(1,495)
Other	(1)				(1)
Net loss	(24,397)				(24,397)
Ending balance at Jun. 30, 2018	176,434	$ 8	530,312	1,179	(355,065)
Ending balance, Shares at Jun. 30, 2018		79,059,764
Beginning balance at Dec. 31, 2018	$ 135,311	$ 8	538,895	940	(404,532)
Beginning balance, Shares at Dec. 31, 2018	79,571,714	79,571,714
Issuance of common stock upon exercise of stock options	$ 251		251
Issuance of common stock upon exercise of stock options, Shares		254,481
Release of restricted stock units		25,850
Stock-based compensation	3,703		3,703
Other comprehensive income (loss)	(449)			(449)
Net loss	(23,427)				(23,427)
Ending balance at Mar. 31, 2019	115,389	$ 8	542,849	491	(427,959)
Ending balance, Shares at Mar. 31, 2019		79,852,045
Beginning balance at Dec. 31, 2018	$ 135,311	$ 8	538,895	940	(404,532)
Beginning balance, Shares at Dec. 31, 2018	79,571,714	79,571,714
Issuance of common stock upon exercise of stock options, Shares	428,406
Unrealized gain/loss on investments	$ 331
Cumulative change in translation adjustment	(229)
Net loss	(42,005)
Ending balance at Jun. 30, 2019	$ 101,050	$ 8	546,537	1,042	(446,537)
Ending balance, Shares at Jun. 30, 2019	80,130,274	80,130,274
Beginning balance at Mar. 31, 2019	$ 115,389	$ 8	542,849	491	(427,959)
Beginning balance, Shares at Mar. 31, 2019		79,852,045
Issuance of common stock upon exercise of stock options	188		188
Issuance of common stock upon exercise of stock options, Shares		173,925
Issuance of common stock under Employee Stock Purchase Plan	164		164
Issuance of common stock under Employee Stock Purchase Plan, Shares		58,748
Release of restricted stock units		45,556
Stock-based compensation	3,336		3,336
Other comprehensive income (loss)	551			551
Unrealized gain/loss on investments	147
Cumulative change in translation adjustment	404
Net loss	(18,578)				(18,578)
Ending balance at Jun. 30, 2019	$ 101,050	$ 8	$ 546,537	$ 1,042	$ (446,537)
Ending balance, Shares at Jun. 30, 2019	80,130,274	80,130,274

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows from Operating Activities
Net loss	$ (42,005)	$ (45,890)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,175	2,178
Amortization of intangible assets	279	299
Impairment of property and equipment	1,177
Non-cash lease expense	436
Accretion of discounts and amortization of premiums on marketable securities	(856)	(519)
Stock-based compensation	7,039	9,251
Loss from remeasurement of fair value of contingent consideration	24	360
Loss on disposal of property and equipment	(2)	3
Deferred income tax	(70)	(59)
Changes in operating assets and liabilities:
Accounts receivable	10,674	(52)
Prepaid expenses and other assets	612	1,540
Accounts payable	(349)	(669)
Deferred revenue	(6,763)	(6,184)
Accrued clinical trial and manufacturing expenses	1,359	(1,740)
Accrued expenses and other liabilities	(1,784)	(3,464)
Operating lease liabilities	468
Net cash used in operating activities	(27,586)	(44,946)
Cash Flows from Investing Activities
Purchase of marketable securities	(133,478)	(155,142)
Proceeds from maturities of marketable securities	114,159	156,174
Purchase of property and equipment	(382)	(825)
Proceeds from sale of property and equipment		4
Net cash (used in) provided by investing activities	(19,701)	211
Cash Flows from Financing Activities
Proceeds from employee stock purchase plan	164	366
Proceeds from exercise of stock options and warrants	439	1,260
Net cash provided by financing activities	603	1,626
Effect of exchange rate changes	(65)	(104)
Net decrease in cash, cash equivalents and restricted cash	(46,749)	(43,213)
Cash, cash equivalents and restricted cash at beginning of period	126,778	158,082
Cash, cash equivalents and restricted cash at end of period	80,029	114,869
Supplemental Disclosure of Non-Cash Investing and Financing Activities
Purchase of property and equipment in accounts payable and accrued liabilities		652
Reconciliation of Cash, Cash Equivalents and Restricted Cash
Cash and cash equivalents	79,561	114,401
Restricted cash	468	468
Cash, cash equivalents and restricted cash at end of period	$ 80,029	$ 114,869

Organization and Nature of Busi

Organization and Nature of Business	6 Months Ended
	Jun. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Nature of Business	1. Organization and Nature of Business Aduro Biotech, Inc., and its wholly owned subsidiaries, or the Company, is an immunotherapy company focused on the discovery, development and commercialization of therapies that are designed to harness the body's natural immune system for the treatment of patients with challenging diseases. The Company is located in Berkeley, California and its wholly-owned subsidiary, Aduro Biotech Holdings, Europe B.V., or Aduro Biotech Europe, is based in the Netherlands. The Company operates in one business segment. The Company’s product candidates in the Stimulator of Interferon Genes (STING) and A Proliferation Inducing Ligand (APRIL) pathways are being investigated in cancer, autoimmune and inflammatory diseases. The Company’s lead STING pathway activator product candidate, ADU-S100 (MIW815), is designed to selectively modulate innate and adaptive immune responses to enhance immune control in oncology. The Company’s anti-APRIL antibody product candidate, BION-1301, is designed to suppress the autoimmune response in patients with IgA nephropathy. The Company is collaborating with a number of leading global pharmaceutical companies to help expand and drive its product pipeline. The Company’s strategy is to rapidly advance best-in-class therapies from its STING and APRIL programs through clinical development and regulatory approval.

Basis of Presentation, Use of E

Basis of Presentation, Use of Estimates and Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation, Use of Estimates and Recent Accounting Pronouncements	2. Basis of Presentation, Use of Estimates and Recent Accounting Pronouncements Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or U.S. GAAP, and follow the requirements of the Securities and Exchange Commission, or the SEC, for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted, and accordingly the balance sheet as of December 31, 2018 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and six months ended June 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any other interim period or for any other future year. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on February 27, 2019. The condensed consolidated financial statements include the accounts of Aduro Biotech, Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and reported amounts of revenue and expenses in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, clinical trial accruals, contingent consideration, income taxes, right-of-use asset, lease obligation, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from these estimates. Leases On January 1, 2019, the Company adopted the new standard on leases, Accounting Standard Codification 842, which establishes a comprehensive new lease accounting model. The following steps were taken to be consistent with the guidance in accounting for leases under the new standard. The Company determines if an arrangement is a lease at inception. The Company elected the practical expedient to adopt the policy to not separate lease and non-lease components. Operating leases are included in operating lease right-of-use (ROU) assets and operating lease liabilities on the Company’s consolidated balance sheets. Operating lease ROU assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options to extend or terminate the lease. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Stock-Based Compensation On January 1, 2019, the Company adopted Accounting Standard Update, or ASU, No. 2018-07, simplifying its accounting for share-based payments to non-employees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The Company measured its stock-based awards made to non-employees based on the estimated fair values of the awards as of the adoption date of January 1, 2019 using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized over the remaining requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures and revised, if necessary, in subsequent periods if actual forfeitures differ from the original estimates. Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326). The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company has evaluated the impact of this guidance and has concluded that adoption of the standard will not have a material impact on its condensed consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13 – Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. The standard eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information, and modifies some disclosure requirements. The new standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted upon issuance of this ASU. Entities making this election to early adopt are permitted to early adopt the eliminated or modified disclosure requirements and delay the adoption of the new disclosure requirements until their effective date. The Company is currently evaluating the impact that the standard will have on its condensed Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASC 842), which establishes a comprehensive new lease accounting model. The new standard: (a) clarifies the definition of a lease; (b) requires a dual approach to lease classification similar to current lease classifications; and (c) causes lessees to recognize leases on the balance sheet as a lease liability with a corresponding ROU asset for leases with a lease-term of more than twelve months. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018, with early adoption permitted. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, an update which provides another transition method, the prospective transition method, which allows entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company adopted the new standard on January 1, 2019 using the prospective transition method. The Company identified all leases and reviewed the leases to determine the impact of ASC 842 on its condensed condensed condensed In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220). The standard update allows for a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017, or the Tax Act. Consequently, the ASU 2018-02 eliminates the stranded tax effects resulting from the Tax Act. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period for reporting periods for which financial statements have not yet been issued. The new standard should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company adopted the new standard on January 1, 2019 and due to the full valuation allowance, the Company concluded that there is no impact on its condensed In June 2018, the FASB issued ASU No. 2018-07 – Compensation-Stock Compensation (Topic 718): Improvements to Non-employee Shared-Based Payment Accounting. The standard update expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. The new standard simplifies several aspects of Topic 718 by expanding the scope of the following areas to account for non-employee shared-based payment transactions: (1) overall measurement objective, (2) measurement date, (3) awards with performance conditions, and (4) classification reassessment of certain equity-classified awards. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted, but no earlier than an entity’s adoption date of Topic 606. The Company adopted the new standard on January 1, 2019. As a result, existing non-employee awards were measured as of the adoption date and the related expense will be recognized over the remaining requisite service period using the straight-line method. New awards made to non-employees will be measured at the grant date. In March 2019, the FASB issued ASU No. 2019-01 – Leases (Topic 842): Codification Improvements. The standard clarifies the codification more generally and/or corrects unintended application of the guidance. The amendments in this standard include the following items: (Issue 1) Determining the fair value of the underlying asset by lessors that are not manufacturers or dealers, (Issue 2) Presentation on the statement of cash flows—sales-type and direct financing leases and (Issue 3) Transition disclosures related to Topic 250, Accounting Changes and Error Corrections. The amendments in this standard clarify the FASB’s original intent by explicitly providing an exception to the paragraph 250-10-50-3 interim disclosure requirements in the Topic 842 transition disclosure requirements. The new standard is effective on the adoption date of ASU No. 2016-02. The Company adopted the standard on January 1, 2019 and concluded that adoption of the standard did not have a material impact on its condensed

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable and accounts payable approximate their fair values due to their short maturities. Assets and liabilities recorded at fair value on a recurring basis in the balance sheets, as well as assets and liabilities measured at fair value on a non-recurring basis or disclosed at fair value, are categorized based upon the level of judgment associated with inputs used to measure their fair values. The accounting guidance for fair value provides a framework for measuring fair value, and requires certain disclosures about how fair value is determined. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance also establishes a three-level valuation hierarchy that prioritizes the inputs to valuation techniques used to measure fair value based upon whether such inputs are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions made by the reporting entity. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1 —Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 —Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 —Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. The Company’s cash equivalents, which include money market funds, are classified as Level 1 because they are valued using quoted market prices. The Company’s marketable securities consist of available-for-sale securities and are generally classified as Level 2 because their value is based on valuations using significant inputs derived from or corroborated by observable market data. In certain cases where there is limited activity or less transparency around the inputs to valuation, securities are classified as Level 3. Level 3 liabilities consist of the contingent consideration liability. The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): June 30, 2019 Level 1 Level 2 Level 3 Total Financial Assets: Money market funds $ 16,306 $ — $ — $ 16,306 U.S. government and agency securities — 65,360 — 65,360 Corporate debt securities — 62,435 — 62,435 Commercial paper — 84,020 — 84,020 Total $ 16,306 $ 211,815 $ — $ 228,121 Financial Liabilities: Contingent consideration related to acquisition $ — $ — $ 1,015 $ 1,015 Total $ — $ — $ 1,015 $ 1,015 December 31, 2018 Level 1 Level 2 Level 3 Total Financial Assets: Money market funds $ 22,082 $ — $ — $ 22,082 U.S. government and agency securities — 59,001 — 59,001 Corporate debt securities — 70,964 — 70,964 Commercial paper — 89,702 — 89,702 Total $ 22,082 $ 219,667 $ — $ 241,749 Financial Liabilities: Contingent consideration related to acquisition $ — $ — $ 998 $ 998 Total $ — $ — $ 998 $ 998 The acquisition-date fair value of the contingent consideration liability represents the future consideration that is contingent upon the achievement of specified development milestones for a product candidate. The fair value of the contingent consideration is based on the Company’s probability-weighted discounted cash flow assessment that considers probability and timing of future payments. The fair value measurement is based on significant Level 3 inputs such as anticipated timelines and probability of achieving development milestones. Changes in the fair value of the liability for contingent consideration, except for the impact of foreign currency, will be recognized in the consolidated statement of operations until settlement. The Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of June 30, 2019 and December 31, 2018. During the six months ended June 30, 2019 and 2018, there were no transfers between the fair value measurement category levels. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Balance at December 31, 2018 $ 998 Net change in fair value upon remeasurement 25 Foreign currency impact on contingent consideration (8 ) Balance at June 30, 2019 $ 1,015 The following tables summarize the estimated value of the Company’s cash, cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands): June 30, 2019 Amortized cost Unrealized gains Unrealized losses Estimated Fair Value Cash and cash equivalents: Cash $ 23,512 $ — $ — $ 23,512 Money market funds 16,306 — — 16,306 Commercial paper 39,749 — (6 ) 39,743 Total cash and cash equivalents $ 79,567 $ — $ (6 ) $ 79,561 Marketable securities: U.S. government and agency securities $ 65,276 $ 93 $ (9 ) $ 65,360 Corporate debt securities 62,362 77 (4 ) 62,435 Commercial paper 44,272 9 (4 ) 44,277 Total marketable securities $ 171,910 $ 179 $ (17 ) $ 172,072 December 31, 2018 Amortized cost Unrealized gains Unrealized losses Estimated Fair Value Cash and cash equivalents: Cash $ 36,124 $ — $ — $ 36,124 Money market funds 22,082 — — 22,082 Commercial paper 62,413 — — 62,413 Corporate debt securities 5,694 — (3 ) 5,691 Total cash and cash equivalents $ 126,313 $ — $ (3 ) $ 126,310 Marketable securities: U.S. government and agency securities $ 59,127 $ 16 $ (142 ) $ 59,001 Corporate debt securities 65,319 3 (49 ) 65,273 Commercial paper 27,289 — — 27,289 Total marketable securities $ 151,735 $ 19 $ (191 ) $ 151,563 The Company’s available-for-sale marketable securities as of June 30, 2019 have contractual maturities of less than one year and are classified as short-term marketable securities on the condensed consolidated balance sheet.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2019
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): June 30, December 31, 2019 2018 Leasehold improvements $ 26,960 $ 26,961 Lab equipment 8,383 8,281 Computer and office equipment 2,325 2,292 Furniture 1,593 1,560 Construction in progress 499 1,458 Total property and equipment 39,760 40,552 Less: accumulated depreciation (13,583 ) (11,395 ) Property and equipment, net $ 26,177 $ 29,157 Depreciation expense was $1.1 million and $1.1 million for the three months ended June 30, 2019 and 2018, respectively, and $2.2 million and $2.2 million for the six months ended June 30, 2019 and 2018, respectively. As a result of the Company’s efforts to wind down programs and prioritize spending, the Company recorded an impairment charge of $1.2 million to research and development expenses within the statement of operations during the three months ended June 30, 2019. The impairment was related to lab equipment which was previously recorded in construction in progress. Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following (in thousands): June 30, December 31, 2019 2018 Compensation and related benefits $ 3,009 $ 4,619 Professional and consulting services 2,139 2,185 Accrued research expense 1,320 1,859 Deferred rent — 653 Accrued property and equipment — 101 Other 1,413 1,101 Total accrued expenses and other liabilities $ 7,881 $ 10,518

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	5. Goodwill and Intangible Assets Goodwill The gross carrying amount of goodwill was as follows (in thousands): Balance at December 31, 2018 $ 8,334 Foreign currency translation adjustment (57 ) Balance at June 30, 2019 $ 8,277 Intangible assets The gross carrying amounts and net book value of intangible assets were as follows (in thousands): June 30, 2019 Gross Amount Accumulated Amortization Net Book Value Intangible assets with finite lives: License agreement $ 11,241 $ 2,061 $ 9,180 Total intangible assets with finite lives 11,241 2,061 9,180 Acquired IPR&D assets 15,504 — 15,504 Total intangible assets $ 26,745 $ 2,061 $ 24,684 December 31, 2018 Gross Amount Impairment (1) Accumulated Amortization Net Book Value Intangible assets with finite lives: License agreement $ 11,318 $ — $ 1,792 $ 9,526 Total intangible assets with finite lives 11,318 — 1,792 9,526 Acquired IPR&D assets 19,626 4,017 — 15,609 Total intangible assets $ 30,944 $ 4,017 $ 1,792 $ 25,135 (1) The amount includes effects of foreign currency exchange rates. Intangible assets are carried at cost less accumulated amortization and impairment. Amortization is over a period of 20 years and the amortization expense is recorded in operating expenses. In the fourth quarter of 2018, the Company recorded an impairment charge of $4.0 million driven by the Company’s decision to discontinue one of its acquired early research programs resulting in impairment of the acquired IPR&D asset. Amortization expense was $0.1 million and $0.1 million for the three months ended June 30, 2019 and 2018, respectively, and $0.3 million and $0.3 million for the six months ended June 30, 2019 and 2018, respectively. Based on finite-lived intangible assets recorded as of June 30, 2019, the estimated future amortization expense for the next five years is as follows (in thousands): Year Ending December 31, Estimated Amortization Expense 2019 (remaining six months) $ 281 2020 562 2021 562 2022 562 2023 562 2024 562

Collaboration Agreements

Collaboration Agreements	6 Months Ended
	Jun. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Agreements	6. Collaboration Agreements Novartis Agreement I n March 2015, the Company entered into a collaboration and license agreement with Novartis Pharmaceuticals Corporation, or Novartis, pursuant to which the Company is collaborating worldwide with Novartis regarding the development and potential commercialization of product candidates containing an agonist of the molecular target known as STING in the field of oncology, including immuno-oncology and cancer vaccines. Under this agreement, or the Novartis Agreement, the Company granted Novartis a co-exclusive license to develop such products worldwide, an exclusive license to commercialize such products outside the United States and a non-exclusive license to support the Company in commercializing such products in the United States if it requests such support. The collaboration is guided by a joint steering committee with each party having final decision-making authority regarding specified areas of development or commercialization. Under the Novartis Agreement, the Company received an upfront payment of $200.0 million in April 2015. During the second quarter of 2016, the Company earned a $35.0 million development milestone upon initiation of a Phase 1 trial for the first STING product candidate, ADU-S100, and recognized the payment as revenue in the period. The Company is also eligible to receive up to an additional $215.0 million in development milestones and up to an additional $250.0 million in regulatory approval milestones. The Company is responsible for 38% of the joint development costs worldwide and Novartis is responsible for the remaining 62% of the joint development costs worldwide. The Company will also receive 50% of gross profits on sales of any products commercialized pursuant to this collaboration in the United States and 45% of gross profits for specified European countries and Japan. For each of these profit share countries, each party will be responsible for its respective commercial sharing percentage of all joint commercialization costs incurred in that country. For all other countries where the Company is not sharing profits, Novartis will be responsible for all commercialization costs and will pay the Company a royalty in the mid-teens on all net sales of product sold by Novartis, its affiliates and sublicensees, with such percentage subject to reduction post patent and data exclusivity expiration and subject to reduction, capped at a specified percentage, for royalties payable to third party licensors. Novartis’ royalty obligation will run on a country-by-country basis until the later of expiration of the last valid claim covering the product, expiration of data exclusivity for the product or 12 years after first commercial sale of the product in such country. With respect to the United States, specified European countries and/or Japan, the Company may elect for such region to either reduce by 50% or to eliminate in full the Company’s development and commercialization cost sharing obligation. If the Company elects to reduce its cost sharing percentage by 50% in any such region, then its profit share in such region will also be reduced by 50%. If the Company elects to eliminate its development cost sharing obligation, then such region will be removed from the profit share, and instead Novartis will owe the Company royalties on any net sales of product for such region, as described above. For revenue recognition purposes, the Company determined that the duration of the contract begins on the effective date in March 2015 and ends upon receipt of regulatory approval, estimated to occur in 2028. The Company’s performance period commenced in May 2015. The transaction price consists of the $200.0 million upfront fee, a $35.0 million milestone payment received in the second quarter of 2016 upon commencement of a Phase 1 study, and $1.7 million in reimbursement of research and development costs through June 30, 2019. The Company determined that the remaining potential milestone payments are probable of significant reversal of cumulative revenue as their achievement is highly dependent on the successful completion of Phase 1 studies. Therefore, these payments are not included in the transaction price. Any consideration related to sales-based royalties and profit-sharing payments will be recognized when the related sales occur as they were determined to relate predominantly to the license granted to Novartis and have been excluded from the transaction price. The transaction price of $236.7 million is allocated to one combined performance obligation. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The Company concluded that it will utilize a cost-based input method to measure its progress toward completion of its performance obligation and to calculate the corresponding amount of revenue to recognize each period. The Company believes this is the best measure of progress because other measures do not reflect how the Company transfers its performance obligation to Novartis. In applying the cost-based input method of revenue recognition, the Company uses actual clinical study enrollment figures as well as actual costs incurred relative to budgeted costs expected to be incurred for the combined performance obligation. These costs consist primarily of internal full-time equivalent effort and third-party contract costs relative to the level of patient enrollment in the study. Revenue will be recognized based on the level of costs incurred relative to the total budgeted costs for the performance obligations. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the Company's performance obligation. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete the Company's performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods. Cost-sharing payments from Novartis are included in the transaction price and subject to the cost-based input method to determine the amount to be recognized in license and collaboration revenue in the Company’s consolidated statements of operations, while cost-sharing payments to Novartis are accounted for as research and development expenses in the Company’s consolidated statements of operations. If the Company recognizes revenue from the sale of any products commercialized pursuant to this collaboration in the United States, it will retain 50% of the gross profits from such sales, and will pay the remaining 50% of the gross profits to Novartis. The Company will receive from Novartis 45% of gross profits for specified European countries and Japan from the sale of any products commercialized pursuant to this collaboration in such countries. Profit sharing payments made to or received from Novartis will be aggregated by product by territory and reported as expenses or revenues, as applicable. For the three months ended June 30, 2019 and 2018, the Company recognized $1.9 million and $2.5 million, respectively, and for the six months ended June 30, 2019 and 2018, the Company recognized $4.4 million and $6.1 million, respectively, in revenue from its collaboration with Novartis. The remaining balance of the transaction price of $172.3 million is included in deferred revenue at June 30, 2019. Lilly Agreement On December 18, 2018, the Company entered into a research collaboration and exclusive license agreement, or the Lilly Agreement, with Lilly for its cGAS-STING Pathway Inhibitor program for the research and development of novel immunotherapies for autoimmune and other inflammatory diseases. Pursuant to the Lilly Agreement, the Company granted an exclusive and worldwide license under certain intellectual property rights controlled by the Company to research, develop, manufacture and commercialize certain cGAS-STING products for the treatment of autoimmune and other inflammatory diseases. The license granted is sublicensable during a specified time period. Under the terms of the Lilly Agreement, the Company received an upfront payment of $12.0 million in the first quarter of 2019. The Company will also be eligible for development and commercial milestones of up to approximately $620.0 million per product. Lilly is also obligated to pay the Company tiered royalty payments at percentages in the single to low-double digits based on annual net sales of the licensed products. Lilly must pay such royalties on a product-by-product and country-by-country basis until the latest to occur of (i) the expiration of the last-to-expire valid claim of certain patents, (ii) the expiration of the data exclusivity period in such country or (iii) a specified anniversary of the first commercial sale of such product in such country. The Company will be reimbursed for up to a certain amount of research funding spent during the research term. In addition, the Company has the option to co-fund the clinical development of each product in exchange for an increase in royalty payments and a reduction in certain milestone payments to the extent relevant to such co-funded product. Lilly will be responsible for all costs of global commercialization. For revenue recognition purposes, the Company determined that the Company’s performance period commenced in January 2019 and ends upon completion of the research term, estimated to occur in 2021. The transaction price consists of the $12.0 million upfront fee and variable consideration related to reimbursement of research and development costs. The Company determined that the remaining potential milestone payments are probable of significant reversal of cumulative revenue as their achievement is highly dependent on the successful completion of research activities and advancement through clinical studies. Therefore, these potential milestone payments are not included in the transaction price. Any consideration related to sales-based royalties and profit-sharing payments will be recognized when the related sales occur as they were determined to relate predominantly to the license granted to Lilly and have been excluded from the transaction price. The transaction price is allocated to one combined performance obligation. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The Company concluded that it will utilize a cost-based input method to measure its progress toward completion of its performance obligation and to calculate the corresponding amount of revenue to recognize each period. The Company believes this is the best measure of progress because other measures do not reflect how the Company transfers its performance obligation to Lilly. In applying the cost-based input method of revenue recognition, the Company uses actual costs incurred relative to budgeted costs expected to be incurred for the combined performance obligation. These costs consist primarily of internal full-time equivalent effort and third-party contract costs. Revenue will be recognized based on the level of costs incurred relative to the total budgeted costs for the performance obligation. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the Company's performance obligation. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete the Company's performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods. For the three months ended June 30, 2019, the Company recognized $3.0 million in revenue. For the six months ended June 30, 2019, the Company recognized $4.4 million in revenue. The Company recorded $9.6 million in deferred revenue at June 30, 2019. Merck License Agreement In connection with the acquisition of Aduro Biotech Europe in October 2015, the Company became party to an agreement with Merck Sharp & Dohme Corp., or Merck. The agreement sets forth the parties’ respective obligations for development, commercialization, regulatory and manufacturing and supply activities for antibody product candidates. The Company identified the following promises under the agreement: 1) the license, 2) the obligation to provide research activities and 3) the obligation to participate on a Joint Research Committee. The Company determined that the promises were not distinct which resulted in them being combined into one performance obligation. The Company completed its performance obligation under the agreement by the end of 2016. The Company received a milestone payment of $2.0 million in 2017 for the initiation of a GLP toxicology study and $3.0 million in the first quarter of 2018 for the initiation of a Phase 1 trial for the anti-CD27 antibody. Both payments were recognized in revenue when received as the Company had no remaining performance obligation. The Company is eligible to receive future contingent payments, including up to $307.0 million in potential development milestone payments, and up to $135.0 million in commercial and net sales milestones for a product candidate. In addition, the Company is eligible to receive royalties in the mid-single digits to low teens based on net sales of the product. Future milestone payments and royalties will be recognized when earned as the Company has no remaining performance obligations under this agreement.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Leases The Company leases one facility in Berkeley, California under an operating lease that has a remaining lease term of 11 years. The Company also leases one facility in Oss, the Netherlands, under an operating lease that expires in December 2020. Both leases contain an option to extend for an additional term, however, the Company is not reasonably certain to exercise the option for either lease. The Company is subleasing approximately 30,885 square feet in its Berkeley facility under subleases that expire on or prior to December 31, 2020. Sublease income was $0.4 million and $0.5 million for the three months ended June 30, 2019 and 2018, respectively, and $0.8 million in each of the six months ended June 30, 2019 and 2018, respectively. During 2016, the Company established a letter of credit with Bank of America Merrill Lynch as security for the Berkeley lease in the amount of $0.5 million. The letter of credit is collateralized by a certificate of deposit for $0.5 million which has been included in restricted cash in the consolidated balance sheet as of June 30, 2019. Future minimum payments under the leases at December 31, 2018 prior to the adoption of the new lease standard, ASC 842, were as follows (in thousands): Year Ending December 31, Amounts 2019 $ 5,519 2020 5,669 2021 5,332 2022 5,460 2023 5,570 Thereafter 35,836 Total future minimum lease payments $ 63,386 As of January 1, 2019, the Company recognized ROU assets and lease liabilities for its operating leases. Aside from the operating leases, there were no other leases, including finance leases, recognized as of January 1, 2019. The maturity of the Company’s operating lease liabilities as of June 30, 2019 is as follows (in thousands): Undiscounted Lease Payments Amounts 2019 (remaining six months) $ 2,788 2020 5,666 2021 5,332 2022 5,460 2023 5,570 Thereafter 35,836 Total undiscounted lease payments 60,652 Present value adjustment 26,423 Total net lease liability $ 34,229 Net lease liability - ST $ 1,630 Net lease liability - LT 32,599 Total net lease liability $ 34,229 Straight-line rent expense recognized for operating leases was $1.2 million and $1.3 million for the three months ended June 30, 2019 and 2018, respectively, and $2.5 million and $2.6 million for the six months ended June 30, 2019 and 2018, respectively. Variable lease payments, including non-lease components such as common area maintenance fees, recognized as rent expense for operating leases were $0.3 million in each of the three month periods ended June 30, 2019 and 2018, respectively, and $0.6 million and $0.5 million for the six months ended June 30, 2019 and 2018, respectively. The following information represents supplemental disclosure for the condensed consolidated statement of cash flows related to operating leases (in thousands): Six months ended June 30, 2019 Cash flows from operating activities Cash paid for amounts included in the measurement of lease liabilities $ 2,727 The following summarizes additional information related to operating leases: June 30, 2019 Weighted-average remaining lease terms (in years) Operating leases 10.32 Weighted-average discount rate Operating leases 12 % Indemnification 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. The Company currently has directors’ and officers’ insurance. Legal The Company is not party to any material legal proceedings at this time. From time to time, the Company may become involved in various legal proceedings that arise in the ordinary course of its business. Other Commitments The Company has various manufacturing, clinical, research and other contracts with vendors in the conduct of the normal course of its business. All contracts are terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, the Company would only be obligated for the products or services that the Company had received at the time the termination became effective as well as non-cancelable and non-refundable obligations, including payment obligations for costs or expenses incurred by the vendor for products or services before the termination became effective. In the case of terminating a clinical trial agreement at a particular site, the Company would also be obligated to provide continued support for appropriate medical procedures at that site until completion or termination.

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Common Stock	8. Common Stock The Company had reserved shares of common stock for future issuance as follows: June 30, 2019 Options issued and outstanding 10,797,308 Shares available for future stock option grants 8,436,766 Restricted stock units 1,290,260 Common stock warrants 61,717 Total 20,586,051 At-the-Market Sales Agreement In August 2017, the Company entered into an “at-the-market” sales agreement, as amended in February 2019, or the 2017 Sales Agreement, with Cowen, through which the Company may offer and sell shares of its common stock having an aggregate offering of up to $100.0 million through Cowen, as the Company’s sales agent. The Company will pay Cowen a commission of up to 3% of the gross proceeds of sales made through the arrangement. There were no sales of shares of common stock pursuant to the 2017 Sales Agreement during the year ended December 31, 2018 or the six months ended June 30, 2019. As of June 30, 2019, the Company had an aggregate of $81.5 million remaining for future sales under the 2017 Sales Agreement, subject to the continued effectiveness of its shelf registration statement on Form S-3 (Registration No. 333-219639) or an effective replacement shelf registration statement.

Equity Incentive Plans

Equity Incentive Plans	6 Months Ended
	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	9. Equity Incentive Plans 2015 Plan In March 2015, the Company’s board of directors adopted and in April 2015 the Company’s stockholders approved the 2015 Equity Incentive Plan, or the 2015 Plan, which became effective upon the initial public offering of the Company’s common stock, or IPO, and provides for the granting of incentive stock options, nonstatutory stock options and other forms of stock awards to its employees, directors and consultants. The Company’s 2009 Stock Incentive Plan, or the 2009 Plan, terminated on the date the 2015 Plan was adopted. Options granted or shares issued under the 2009 Plan that were outstanding on the date the 2015 Plan became effective will remain subject to the terms of the 2009 Plan. The 2015 Plan is administered by the board of directors or a committee appointed by the board of directors, which determines the types of awards to be granted, including the number of shares subject to the awards, the exercise price and the vesting schedule. The exercise price of incentive stock options and nonqualified stock options will be no less than 100% of the fair value per share of the Company’s common stock on the date of grant. If an individual owns capital stock representing more than 10% of the voting shares, the price of each share will be at least 110% of the fair value on the date of grant. Options expire after 10 years (five years for stockholders owning greater than 10% of the voting stock). The number of shares of common stock initially reserved for issuance under the 2015 Plan was 6,134,292 shares with an automatic annual increase to the shares issuable under the 2015 Plan to the lower of (i) 4% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (ii) a lower number determined by the board of directors. On January 1, 2019, the shares issuable under the 2015 Plan increased by 3,182,868. The Company had 8,436,766 shares available for future grant under the 2015 Plan as of June 30, 2019. 2009 Plan The Company’s 2009 Stock Incentive Plan, or the 2009 Plan, terminated on the date the 2015 Plan was adopted. Options granted or shares issued under the 2009 Plan that were outstanding on the date the 2015 Plan became effective will remain subject to the terms of the 2009 Plan. Prior to the 2009 Plan termination, the number of options available for grant was increased by 360,000 shares. At June 30, 2019, 3,013,117 options under the 2009 Plan remained outstanding. Stock Options The following table summarizes stock option activity for the six months ended June 30, 2019: Options Outstanding Shares Available for Grant Number of Shares Underlying Options Weighted- Average Exercise Price Aggregate Intrinsic Value (In Balance—December 31, 2018 7,255,050 8,986,010 $ 7.54 $ 5,458 Authorized 3,182,868 — RSUs forfeited, net of grants 238,552 — Granted (4,617,300 ) 4,617,300 3.79 Exercised — (428,406 ) 1.02 Canceled 2,377,596 (2,377,596 ) 9.63 Balance—June 30, 2019 8,436,766 10,797,308 $ 5.74 $ 1,466 Options exercisable—June 30, 2019 5,444,742 $ 6.64 $ 1,466 Options vested and expected to vest—June 30, 2019 9,760,686 $ 5.88 $ 1,466 The aggregate intrinsic value represents the difference between the exercise price of the options and the closing price of the Company’s common stock. The aggregate intrinsic value of options exercised during the three and six months ended June 30, 2019 was $0.4 million and $1.1 million, respectively. As of June 30, 2019, the total unrecognized compensation expense related to unvested options, net of estimated forfeitures, was $13.5 million, which the Company expects to recognize over an estimated weighted-average period of 3.1 years. Restricted Stock Units (RSUs) In September 2016, the Company’s board of directors authorized the issuance of restricted stock units, or RSUs, under the 2015 Plan and adopted a form of restricted stock unit grant notice and restricted stock unit award agreement, which is intended to serve as a standard form agreement for RSU grants issued to employees, executive officers, directors and consultants. The following table summarizes RSU activity for the six months ended June 30, 2019: RSUs Outstanding Number of Restricted Units Weighted- Average Grant Date Fair Share Balance—December 31, 2018 1,600,218 $ 8.81 Granted 275,000 1.74 Vested (71,406 ) 10.17 Forfeited (513,552 ) 8.66 Balance—June 30, 2019 1,290,260 $ 7.28 The fair value of RSUs is determined on the date of grant based on the market price of the Company’s common stock on that date. As of June 30, 2019, there was $5.7 million of unrecognized stock-based compensation expense, net of estimated forfeitures, related to RSUs which is expected to be recognized over a weighted-average period of 2.3 years. 2015 Employee Stock Purchase Plan In March 2015, the Company’s board of directors adopted and in April 2015 the Company’s stockholders approved the 2015 Employee Stock Purchase Plan, or 2015 ESPP, which became effective upon the IPO. The 2015 ESPP is intended to qualify as an employee stock purchase plan under Section 423 of the Internal Revenue Code, or the Code, and is administered by the Company’s board of directors and the compensation Committee of the board of directors. The number of shares of common stock initially reserved for issuance under the 2015 ESPP was 720,000 shares with an automatic annual increase to the shares issuable under the 2015 ESPP equal to the lower of (i) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (ii) a lower number determined by the board of directors. There was no annual increase of shares issuable under the 2015 ESPP on January 1, 2019. The Company had 1,622,920 shares available for future issuance under the 2015 ESPP as of June 30, 2019. As of June 30, 2019, the total unrecognized compensation expense related to the 2015 ESPP was $0.1 million, which the Company expects to recognize over an estimated weighted-average period of 0.4 years. The following table summarizes the assumptions used in the Black-Scholes option-pricing model to determine fair value of the Company’s common shares to be issued under the 2015 ESPP: Six Months Ended June 30, 2019 2018 Expected term (in years) 0.5 0.5 Volatility 58.9% 54.5% Risk-free interest rate 2.43% 2.09% Dividend yield —% —% Stock-based Compensation Expense Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 1,713 $ 2,539 $ 3,746 $ 5,284 General and administrative 1,623 1,788 3,293 3,967 Total stock-based compensation expense $ 3,336 $ 4,327 $ 7,039 $ 9,251 In determining the fair value of the stock-based awards, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment. Fair Value of Common Stock. Prior to the IPO in April 2015, the board of directors determined the fair value of the Company’s common stock by taking into consideration, among other things, contemporaneous valuations of the common stock prepared by an unrelated third-party valuation firm. Given the previous absence of a public trading market for the common stock, the board of directors exercised reasonable judgment and considered a number of objective and subjective factors to determine the best estimate of the fair value of the common stock, including the Company’s stage of development; progress of its research and development efforts; the rights, preferences and privileges of its preferred stock relative to those of its common stock; equity market conditions affecting comparable public companies and the lack of marketability of the common stock. Since the Company’s IPO, it has used the market closing price of its common stock as reported on the Nasdaq Global Select Market. Expected Term —The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). Expected Volatility —Because the Company does not have a long trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded biopharmaceutical companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option. Expected Dividend —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. The fair value of stock option awards granted to employees was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Six Months Ended June 30, 2019 2018 Expected term (in years) 5.32 - 6.08 5.32 - 6.05 Volatility 67.2 - 70.4% 71.6 - 71.7% Risk-free interest rate 1.96 - 2.40% 2.38 - 2.87% Dividend yield —% —% For the three months ended June 30, 2019 and 2018, the Company recognized $3.3 million and $4.3 million, respectively, and for the six months ended June 30, 2019 and 2018, the Company recognized $7.0 million and $9.1 million, respectively, of stock-based compensation related to options granted to employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. The Company uses the fair value method to value options granted to nonemployees. For the three months ended June 30, 2019 and 2018, the Company recognized stock-based compensation of $19,000 and $0.1 million, respectively, and for the six months ended June 30, 2019 and 2018, the Company recognized stock-based compensation of $44,000 and $0.1 million, respectively, related to options granted to nonemployees. Beginning on January 1, 2019, the Company adopted ASU 2018-07 and measured its stock-based awards made to non-employees based on the estimated fair values of the awards as of the adoption date of January 1, 2019 using the Black-Scholes option-pricing model and recognized expense over the remaining requisite service period using the straight-line method. As a result, the stock-based compensation amount recognized for the six months ended June 30, 2019 reflects the adoption of ASU 2018-07 as of January 1, 2019 while the stock-based compensation amount recognized for the six months ended June 30, 2018 reflects the amount prior to the recently adopted standard. The fair value of stock option awards granted to nonemployees was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Six Months Ended June 30, 2019 2018 Expected term (in years) 6.17 - 9.66 6.17 - 9.60 Volatility 70.5 - 70.8% 71.6 - 71.7% Risk-free interest rate 2.66 - 3.19% 2.66 - 2.94% Dividend yield —% —%

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes Income tax benefit for the six months ended June 30, 2019 and 2018 was approximately $70,000 and $59,000, respectively. The income tax benefit recorded for the six months ended June 30, 2019 and June 30, 2018 were both primarily related to the foreign deferred tax benefit from the amortization of intangibles. The Company’s policy is to recognize interest and penalties related to unrecognized tax benefits in income tax expense. The Company files income tax returns in the United States and Netherlands. The federal and state income tax returns are open under the statute of limitations subject to tax examinations for the tax years ended December 31, 2015 through December 31, 2017. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the IRS or state tax authorities to the extent utilized in a future period. For the Netherlands, the tax administration can impose an additional assessment within five years from the year in which the tax debt originated.

Net Loss Per Common Share

Net Loss Per Common Share	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Loss Per Common Share	11. Net Loss per Common Share Since the Company was in a loss position for all periods presented, diluted net loss per common share is the same as basic net loss per common share for all periods presented as the inclusion of all potential common shares outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per common share calculations because they would be anti-dilutive were as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Options to purchase common stock 10,797,308 9,620,114 10,797,308 9,620,114 Restricted stock units 1,290,260 1,165,848 1,290,260 1,165,848 Common stock warrants 61,717 63,661 61,717 63,661 Total 12,149,285 10,849,623 12,149,285 10,849,623

Basis of Presentation, Use of_2

Basis of Presentation, Use of Estimates and Recent Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or U.S. GAAP, and follow the requirements of the Securities and Exchange Commission, or the SEC, for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted, and accordingly the balance sheet as of December 31, 2018 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and six months ended June 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any other interim period or for any other future year. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on February 27, 2019. The condensed consolidated financial statements include the accounts of Aduro Biotech, Inc. and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and reported amounts of revenue and expenses in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, clinical trial accruals, contingent consideration, income taxes, right-of-use asset, lease obligation, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from these estimates.
Leases	Leases On January 1, 2019, the Company adopted the new standard on leases, Accounting Standard Codification 842, which establishes a comprehensive new lease accounting model. The following steps were taken to be consistent with the guidance in accounting for leases under the new standard. The Company determines if an arrangement is a lease at inception. The Company elected the practical expedient to adopt the policy to not separate lease and non-lease components. Operating leases are included in operating lease right-of-use (ROU) assets and operating lease liabilities on the Company’s consolidated balance sheets. Operating lease ROU assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options to extend or terminate the lease. Lease expense for lease payments is recognized on a straight-line basis over the lease term.
Share-Based Compensation	Stock-Based Compensation On January 1, 2019, the Company adopted Accounting Standard Update, or ASU, No. 2018-07, simplifying its accounting for share-based payments to non-employees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The Company measured its stock-based awards made to non-employees based on the estimated fair values of the awards as of the adoption date of January 1, 2019 using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized over the remaining requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures and revised, if necessary, in subsequent periods if actual forfeitures differ from the original estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326). The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company has evaluated the impact of this guidance and has concluded that adoption of the standard will not have a material impact on its condensed consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13 – Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. The standard eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information, and modifies some disclosure requirements. The new standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted upon issuance of this ASU. Entities making this election to early adopt are permitted to early adopt the eliminated or modified disclosure requirements and delay the adoption of the new disclosure requirements until their effective date. The Company is currently evaluating the impact that the standard will have on its condensed
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASC 842), which establishes a comprehensive new lease accounting model. The new standard: (a) clarifies the definition of a lease; (b) requires a dual approach to lease classification similar to current lease classifications; and (c) causes lessees to recognize leases on the balance sheet as a lease liability with a corresponding ROU asset for leases with a lease-term of more than twelve months. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018, with early adoption permitted. A modified retrospective transition approach is required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, an update which provides another transition method, the prospective transition method, which allows entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company adopted the new standard on January 1, 2019 using the prospective transition method. The Company identified all leases and reviewed the leases to determine the impact of ASC 842 on its condensed condensed condensed In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220). The standard update allows for a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017, or the Tax Act. Consequently, the ASU 2018-02 eliminates the stranded tax effects resulting from the Tax Act. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period for reporting periods for which financial statements have not yet been issued. The new standard should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company adopted the new standard on January 1, 2019 and due to the full valuation allowance, the Company concluded that there is no impact on its condensed In June 2018, the FASB issued ASU No. 2018-07 – Compensation-Stock Compensation (Topic 718): Improvements to Non-employee Shared-Based Payment Accounting. The standard update expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. The new standard simplifies several aspects of Topic 718 by expanding the scope of the following areas to account for non-employee shared-based payment transactions: (1) overall measurement objective, (2) measurement date, (3) awards with performance conditions, and (4) classification reassessment of certain equity-classified awards. The new standard is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted, but no earlier than an entity’s adoption date of Topic 606. The Company adopted the new standard on January 1, 2019. As a result, existing non-employee awards were measured as of the adoption date and the related expense will be recognized over the remaining requisite service period using the straight-line method. New awards made to non-employees will be measured at the grant date. In March 2019, the FASB issued ASU No. 2019-01 – Leases (Topic 842): Codification Improvements. The standard clarifies the codification more generally and/or corrects unintended application of the guidance. The amendments in this standard include the following items: (Issue 1) Determining the fair value of the underlying asset by lessors that are not manufacturers or dealers, (Issue 2) Presentation on the statement of cash flows—sales-type and direct financing leases and (Issue 3) Transition disclosures related to Topic 250, Accounting Changes and Error Corrections. The amendments in this standard clarify the FASB’s original intent by explicitly providing an exception to the paragraph 250-10-50-3 interim disclosure requirements in the Topic 842 transition disclosure requirements. The new standard is effective on the adoption date of ASU No. 2016-02. The Company adopted the standard on January 1, 2019 and concluded that adoption of the standard did not have a material impact on its condensed

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): June 30, 2019 Level 1 Level 2 Level 3 Total Financial Assets: Money market funds $ 16,306 $ — $ — $ 16,306 U.S. government and agency securities — 65,360 — 65,360 Corporate debt securities — 62,435 — 62,435 Commercial paper — 84,020 — 84,020 Total $ 16,306 $ 211,815 $ — $ 228,121 Financial Liabilities: Contingent consideration related to acquisition $ — $ — $ 1,015 $ 1,015 Total $ — $ — $ 1,015 $ 1,015 December 31, 2018 Level 1 Level 2 Level 3 Total Financial Assets: Money market funds $ 22,082 $ — $ — $ 22,082 U.S. government and agency securities — 59,001 — 59,001 Corporate debt securities — 70,964 — 70,964 Commercial paper — 89,702 — 89,702 Total $ 22,082 $ 219,667 $ — $ 241,749 Financial Liabilities: Contingent consideration related to acquisition $ — $ — $ 998 $ 998 Total $ — $ — $ 998 $ 998
Summary of Changes in Fair Value of Level 3 Financial Liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Balance at December 31, 2018 $ 998 Net change in fair value upon remeasurement 25 Foreign currency impact on contingent consideration (8 ) Balance at June 30, 2019 $ 1,015
Summary of Estimated Value of Cash, Cash Equivalents and Marketable Securities and Gross Unrealized Holding Gains and Losses	The following tables summarize the estimated value of the Company’s cash, cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands): June 30, 2019 Amortized cost Unrealized gains Unrealized losses Estimated Fair Value Cash and cash equivalents: Cash $ 23,512 $ — $ — $ 23,512 Money market funds 16,306 — — 16,306 Commercial paper 39,749 — (6 ) 39,743 Total cash and cash equivalents $ 79,567 $ — $ (6 ) $ 79,561 Marketable securities: U.S. government and agency securities $ 65,276 $ 93 $ (9 ) $ 65,360 Corporate debt securities 62,362 77 (4 ) 62,435 Commercial paper 44,272 9 (4 ) 44,277 Total marketable securities $ 171,910 $ 179 $ (17 ) $ 172,072 December 31, 2018 Amortized cost Unrealized gains Unrealized losses Estimated Fair Value Cash and cash equivalents: Cash $ 36,124 $ — $ — $ 36,124 Money market funds 22,082 — — 22,082 Commercial paper 62,413 — — 62,413 Corporate debt securities 5,694 — (3 ) 5,691 Total cash and cash equivalents $ 126,313 $ — $ (3 ) $ 126,310 Marketable securities: U.S. government and agency securities $ 59,127 $ 16 $ (142 ) $ 59,001 Corporate debt securities 65,319 3 (49 ) 65,273 Commercial paper 27,289 — — 27,289 Total marketable securities $ 151,735 $ 19 $ (191 ) $ 151,563

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2019
Balance Sheet Related Disclosures [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): June 30, December 31, 2019 2018 Leasehold improvements $ 26,960 $ 26,961 Lab equipment 8,383 8,281 Computer and office equipment 2,325 2,292 Furniture 1,593 1,560 Construction in progress 499 1,458 Total property and equipment 39,760 40,552 Less: accumulated depreciation (13,583 ) (11,395 ) Property and equipment, net $ 26,177 $ 29,157
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following (in thousands): June 30, December 31, 2019 2018 Compensation and related benefits $ 3,009 $ 4,619 Professional and consulting services 2,139 2,185 Accrued research expense 1,320 1,859 Deferred rent — 653 Accrued property and equipment — 101 Other 1,413 1,101 Total accrued expenses and other liabilities $ 7,881 $ 10,518

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The gross carrying amount of goodwill was as follows (in thousands): Balance at December 31, 2018 $ 8,334 Foreign currency translation adjustment (57 ) Balance at June 30, 2019 $ 8,277
Schedule of Intangible Assets	The gross carrying amounts and net book value of intangible assets were as follows (in thousands): June 30, 2019 Gross Amount Accumulated Amortization Net Book Value Intangible assets with finite lives: License agreement $ 11,241 $ 2,061 $ 9,180 Total intangible assets with finite lives 11,241 2,061 9,180 Acquired IPR&D assets 15,504 — 15,504 Total intangible assets $ 26,745 $ 2,061 $ 24,684 December 31, 2018 Gross Amount Impairment (1) Accumulated Amortization Net Book Value Intangible assets with finite lives: License agreement $ 11,318 $ — $ 1,792 $ 9,526 Total intangible assets with finite lives 11,318 — 1,792 9,526 Acquired IPR&D assets 19,626 4,017 — 15,609 Total intangible assets $ 30,944 $ 4,017 $ 1,792 $ 25,135 (1) The amount includes effects of foreign currency exchange rates.
Schedule of Finite-Lived Intangible Assets Estimated Future Amortization Expense	Based on finite-lived intangible assets recorded as of June 30, 2019, the estimated future amortization expense for the next five years is as follows (in thousands): Year Ending December 31, Estimated Amortization Expense 2019 (remaining six months) $ 281 2020 562 2021 562 2022 562 2023 562 2024 562

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments under the Leases	Future minimum payments under the leases at December 31, 2018 prior to the adoption of the new lease standard, ASC 842, were as follows (in thousands): Year Ending December 31, Amounts 2019 $ 5,519 2020 5,669 2021 5,332 2022 5,460 2023 5,570 Thereafter 35,836 Total future minimum lease payments $ 63,386
Schedule of Maturity of Operating Lease Liabilities	The maturity of the Company’s operating lease liabilities as of June 30, 2019 is as follows (in thousands): Undiscounted Lease Payments Amounts 2019 (remaining six months) $ 2,788 2020 5,666 2021 5,332 2022 5,460 2023 5,570 Thereafter 35,836 Total undiscounted lease payments 60,652 Present value adjustment 26,423 Total net lease liability $ 34,229 Net lease liability - ST $ 1,630 Net lease liability - LT 32,599 Total net lease liability $ 34,229
Schedule of Supplemental Disclosure Cash Flow Related to Operating Leases	The following information represents supplemental disclosure for the condensed consolidated statement of cash flows related to operating leases (in thousands): Six months ended June 30, 2019 Cash flows from operating activities Cash paid for amounts included in the measurement of lease liabilities $ 2,727
Schedule of Additional Information Related to Operating Leases	The following summarizes additional information related to operating leases: June 30, 2019 Weighted-average remaining lease terms (in years) Operating leases 10.32 Weighted-average discount rate Operating leases 12 %

Common Stock (Tables)

Common Stock (Tables)	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Schedule of Common Share Reserved for Future Issuance	The Company had reserved shares of common stock for future issuance as follows: June 30, 2019 Options issued and outstanding 10,797,308 Shares available for future stock option grants 8,436,766 Restricted stock units 1,290,260 Common stock warrants 61,717 Total 20,586,051

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	6 Months Ended
	Jun. 30, 2019
Summary of Stock Option Plan Activity	Stock Options The following table summarizes stock option activity for the six months ended June 30, 2019: Options Outstanding Shares Available for Grant Number of Shares Underlying Options Weighted- Average Exercise Price Aggregate Intrinsic Value (In Balance—December 31, 2018 7,255,050 8,986,010 $ 7.54 $ 5,458 Authorized 3,182,868 — RSUs forfeited, net of grants 238,552 — Granted (4,617,300 ) 4,617,300 3.79 Exercised — (428,406 ) 1.02 Canceled 2,377,596 (2,377,596 ) 9.63 Balance—June 30, 2019 8,436,766 10,797,308 $ 5.74 $ 1,466 Options exercisable—June 30, 2019 5,444,742 $ 6.64 $ 1,466 Options vested and expected to vest—June 30, 2019 9,760,686 $ 5.88 $ 1,466
Summary of Restricted Stock Unit or RSU Activity	The following table summarizes RSU activity for the six months ended June 30, 2019: RSUs Outstanding Number of Restricted Units Weighted- Average Grant Date Fair Share Balance—December 31, 2018 1,600,218 $ 8.81 Granted 275,000 1.74 Vested (71,406 ) 10.17 Forfeited (513,552 ) 8.66 Balance—June 30, 2019 1,290,260 $ 7.28
Summary of Stock-Based Compensation	Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 1,713 $ 2,539 $ 3,746 $ 5,284 General and administrative 1,623 1,788 3,293 3,967 Total stock-based compensation expense $ 3,336 $ 4,327 $ 7,039 $ 9,251
Employees
Schedule of Black-Scholes Option-Pricing Model	The fair value of stock option awards granted to employees was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Six Months Ended June 30, 2019 2018 Expected term (in years) 5.32 - 6.08 5.32 - 6.05 Volatility 67.2 - 70.4% 71.6 - 71.7% Risk-free interest rate 1.96 - 2.40% 2.38 - 2.87% Dividend yield —% —%
Non Employees
Schedule of Black-Scholes Option-Pricing Model	The fair value of stock option awards granted to nonemployees was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Six Months Ended June 30, 2019 2018 Expected term (in years) 6.17 - 9.66 6.17 - 9.60 Volatility 70.5 - 70.8% 71.6 - 71.7% Risk-free interest rate 2.66 - 3.19% 2.66 - 2.94% Dividend yield —% —%
2015 ESPP
Schedule of Black-Scholes Option-Pricing Model	The following table summarizes the assumptions used in the Black-Scholes option-pricing model to determine fair value of the Company’s common shares to be issued under the 2015 ESPP: Six Months Ended June 30, 2019 2018 Expected term (in years) 0.5 0.5 Volatility 58.9% 54.5% Risk-free interest rate 2.43% 2.09% Dividend yield —% —%

Net Loss per Common Share (Tabl

Net Loss per Common Share (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Per Common Share	Potentially dilutive securities that were not included in the diluted per common share calculations because they would be anti-dilutive were as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Options to purchase common stock 10,797,308 9,620,114 10,797,308 9,620,114 Restricted stock units 1,290,260 1,165,848 1,290,260 1,165,848 Common stock warrants 61,717 63,661 61,717 63,661 Total 12,149,285 10,849,623 12,149,285 10,849,623

Organization and Nature of Bu_2

Organization and Nature of Business - Additional Information (Details)	6 Months Ended
	Jun. 30, 2019Segment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of business segments	1

Basis of Presentation, Use of_3

Basis of Presentation, Use of Estimates and Recent Accounting Pronouncements - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Right-of-use asset	$ 21,609
Lease liability	$ 34,229
ASC 842
Summary Of Significant Accounting Policies [Line Items]
Right-of-use asset		$ 22,100
Lease liability		33,800
Derecognition of deferred rent		$ 11,700

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financial Assets:
Financial Assets, fair value	$ 228,121	$ 241,749
Financial Liabilities:
Financial Liabilities, fair value	1,015	998
Contingent Consideration Related To Acquisition
Financial Liabilities:
Financial Liabilities, fair value	1,015	998
Money Market Funds
Financial Assets:
Financial Assets, fair value	16,306	22,082
U.S. Government and Agency Securities
Financial Assets:
Financial Assets, fair value	65,360	59,001
Corporate Debt Securities
Financial Assets:
Financial Assets, fair value	62,435	70,964
Commercial Paper
Financial Assets:
Financial Assets, fair value	84,020	89,702
Level 1
Financial Assets:
Financial Assets, fair value	16,306	22,082
Level 1 | Money Market Funds
Financial Assets:
Financial Assets, fair value	16,306	22,082
Level 2
Financial Assets:
Financial Assets, fair value	211,815	219,667
Level 2 | U.S. Government and Agency Securities
Financial Assets:
Financial Assets, fair value	65,360	59,001
Level 2 | Corporate Debt Securities
Financial Assets:
Financial Assets, fair value	62,435	70,964
Level 2 | Commercial Paper
Financial Assets:
Financial Assets, fair value	84,020	89,702
Level 3
Financial Liabilities:
Financial Liabilities, fair value	1,015	998
Level 3 | Contingent Consideration Related To Acquisition
Financial Liabilities:
Financial Liabilities, fair value	$ 1,015	$ 998

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assets transferred from level 1 to level 2	$ 0	$ 0
Fair value assets transferred from level 2 to level 1	0	0
Fair value liabilities transferred from level 1 to level 2	0	0
Fair value liabilities transferred from level 2 to level 1	0	0
Fair value assets transferred into level 3	0	0
Fair value assets transferred out of level 3	0	0
Fair value liabilities transferred into level 3	0	0
Fair value liabilities transferred out of level 3	$ 0	$ 0
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale marketable securities, contractual term	1 year
Fair Value, Measurements, Nonrecurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets measured at fair value on a nonrecurring basis	$ 0		$ 0
Financial liabilities measured at fair value on a nonrecurring basis	$ 0		$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Level 3 Financial Liabilities (Details) - Contingent Consideration $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning balance	$ 998
Net change in fair value upon remeasurement	25
Foreign currency impact on contingent consideration	(8)
Ending balance	$ 1,015

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Estimated Value of Cash, Cash Equivalents and Marketable Securities and Gross Unrealized Holding Gains and Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Amortized cost	$ 79,567	$ 126,313
Cash and cash equivalents, Unrealized losses	(6)	(3)
Cash and cash equivalents, Estimated Fair Value	79,561	126,310
Marketable securities, Amortized cost	171,910	151,735
Marketable securities, Unrealized gains	179	19
Marketable securities, Unrealized losses	(17)	(191)
Marketable securities, Estimated Fair Value	172,072	151,563
Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Amortized cost	23,512	36,124
Cash and cash equivalents, Estimated Fair Value	23,512	36,124
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Amortized cost	16,306	22,082
Cash and cash equivalents, Estimated Fair Value	16,306	22,082
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Amortized cost	39,749	62,413
Cash and cash equivalents, Unrealized losses	(6)
Cash and cash equivalents, Estimated Fair Value	39,743	62,413
U.S. Government and Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, Amortized cost	65,276	59,127
Marketable securities, Unrealized gains	93	16
Marketable securities, Unrealized losses	(9)	(142)
Marketable securities, Estimated Fair Value	65,360	59,001
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Amortized cost		5,694
Cash and cash equivalents, Unrealized losses		(3)
Cash and cash equivalents, Estimated Fair Value		5,691
Marketable securities, Amortized cost	62,362	65,319
Marketable securities, Unrealized gains	77	3
Marketable securities, Unrealized losses	(4)	(49)
Marketable securities, Estimated Fair Value	62,435	65,273
Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, Amortized cost	44,272	27,289
Marketable securities, Unrealized gains	9
Marketable securities, Unrealized losses	(4)
Marketable securities, Estimated Fair Value	$ 44,277	$ 27,289

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 39,760	$ 40,552
Less: accumulated depreciation	(13,583)	(11,395)
Property and equipment, net	26,177	29,157
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	26,960	26,961
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,383	8,281
Computer and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,325	2,292
Furniture
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,593	1,560
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 499	$ 1,458

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property Plant And Equipment [Line Items]
Depreciation	$ 1,100	$ 1,100	$ 2,200	$ 2,200
Impairment charge of asset			$ 1,177
Research and Development Expense
Property Plant And Equipment [Line Items]
Impairment charge of asset	$ 1,200

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Compensation and related benefits	$ 3,009	$ 4,619
Professional and consulting services	2,139	2,185
Accrued research expense	1,320	1,859
Deferred rent		653
Accrued property and equipment		101
Other	1,413	1,101
Total accrued expenses and other liabilities	$ 7,881	$ 10,518

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Schedule of Goodwill (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning Balance	$ 8,334
Foreign currency translation adjustment	(57)
Ending Balance	$ 8,277

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Finite Lived Intangible Assets, Gross Carrying Amount	$ 11,241	$ 11,318
Finite Lived Intangible Assets, Accumulated Amortization	2,061	1,792
Finite Lived Intangible Assets, Net Book Value	9,180	9,526
Indefinite-Lived Intangible Assets, Impairment		4,017
Intangible Assets, Gross Carrying Amount	26,745	30,944
Intangible assets, Net Book Value	24,684	25,135
License agreement
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Finite Lived Intangible Assets, Gross Carrying Amount	11,241	11,318
Finite Lived Intangible Assets, Accumulated Amortization	2,061	1,792
Finite Lived Intangible Assets, Net Book Value	9,180	9,526
Acquired IPR&D assets
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Gross Carrying Amount	15,504	19,626
Indefinite-Lived Intangible Assets, Impairment		4,017
Indefinite-Lived Intangible Assets, Net Book Value	$ 15,504	$ 15,609

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Goodwill And Intangible Assets [Line Items]
Amortization of intangible assets	$ 139		$ 147	$ 279	$ 299
Novartis
Goodwill And Intangible Assets [Line Items]
Intangible assets, amortization period				20 years
Acquired IPR&D assets
Goodwill And Intangible Assets [Line Items]
Intangible assets, impairment		$ 4,000

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Schedule of Finite-Lived Intangible Assets Estimated Future Amortization Expense (Details) $ in Thousands	Jun. 30, 2019USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2019 (remaining six months)	$ 281
2020	562
2021	562
2022	562
2023	562
2024	$ 562

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended					6 Months Ended		12 Months Ended	51 Months Ended
	Apr. 30, 2015	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2016	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2019
Novartis Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments received under collaboration agreement	$ 200,000,000					$ 35,000,000				$ 1,700,000
Novartis share of joint development costs							38.00%
Period after first commercial sale of product on which Novartis' royalty obligation run on a country to country basis							12 years
Transaction price allocated to combined performance obligation							$ 236,700,000
Revenue recognized		$ 1,900,000		$ 2,500,000			4,400,000	$ 6,100,000
Deferred revenue		172,300,000					$ 172,300,000			172,300,000
Novartis Agreement | United States
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement profit share percentage							50.00%
Novartis Agreement | European Countries and Japan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement profit share percentage							45.00%
Novartis Agreement | United States, Specified European Countries and /or Japan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative Agreement, Obligations							With respect to the United States, specified European countries and/or Japan, the Company may elect for such region to either reduce by 50% or to eliminate in full the Company’s development and commercialization cost sharing obligation. If the Company elects to reduce its cost sharing percentage by 50% in any such region, then its profit share in such region will also be reduced by 50%. If the Company elects to eliminate its development cost sharing obligation, then such region will be removed from the profit share, and instead Novartis will owe the Company royalties on any net sales of product for such region, as described above.
Reduction percentage of development cost share							50.00%
Reduction percentage of profit share							50.00%
Novartis Agreement | Novartis
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Novartis share of joint development costs							62.00%
Collaborative arrangement profit share percentage							50.00%
Novartis Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestones amount eligible to receive							$ 215,000,000
Regulatory approval milestones amount eligible to receive							250,000,000
Lilly Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments received under collaboration agreement			$ 12,000,000				12,000,000
Revenue recognized		3,000,000					4,400,000
Deferred revenue		$ 9,600,000					$ 9,600,000			$ 9,600,000
Royalty payments receivable terms							Lilly is also obligated to pay the Company tiered royalty payments at percentages in the single to low-double digits based on annual net sales of the licensed products. Lilly must pay such royalties on a product-by-product and country-by-country basis until the latest to occur of (i) the expiration of the last-to-expire valid claim of certain patents, (ii) the expiration of the data exclusivity period in such country or (iii) a specified anniversary of the first commercial sale of such product in such country.
Lilly Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone amount eligible to receive for products or product candidates							$ 620,000,000
Merck License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payments received under collaboration agreement					$ 3,000,000				$ 2,000,000
Remaining performance obligations					$ 0				$ 0
Merck License Agreement | Maximum | Product Candidate
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone amount eligible to receive for products or product candidates							307,000,000
Merck License Agreement | Maximum | Product
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone amount eligible to receive for products or product candidates							$ 135,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)ft²LeaseFacility	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)ft²LeaseFacility	Jun. 30, 2018USD ($)	Dec. 31, 2016USD ($)
Operating Leased Assets [Line Items]
Operating lease, remaining lease term	10 years 3 months 25 days		10 years 3 months 25 days
Security deposit	$ 0.5		$ 0.5
Operating leases rent expense	1.2	$ 1.3	2.5	$ 2.6
Operating Leases variable lease payments	$ 0.3	0.3	$ 0.6	0.5
Bank Of America Merrill Lynch
Operating Leased Assets [Line Items]
Letter of credit outstanding					$ 0.5
Berkeley, California
Operating Leased Assets [Line Items]
Operating lease, remaining lease term	11 years		11 years
Number of lease facility | LeaseFacility	1		1
Berkeley, California | Sublease
Operating Leased Assets [Line Items]
Total square footage of leased property | ft²	30,885		30,885
Lease expiration date			Dec. 31, 2020
Sublease Income	$ 0.4	$ 0.5	$ 0.8	$ 0.8
Oss, Netherlands
Operating Leased Assets [Line Items]
Operating leases term of expiration			2020-12
Number of lease facility | LeaseFacility	1		1

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments Under the Leases (Details) $ in Thousands	Jun. 30, 2019USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 5,519
2020	5,669
2021	5,332
2022	5,460
2023	5,570
Thereafter	35,836
Total future minimum lease payments	$ 63,386

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Maturity of Company's Operating Lease Liabilities (Details) $ in Thousands	Jun. 30, 2019USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019 (remaining six months)	$ 2,788
2020	5,666
2021	5,332
2022	5,460
2023	5,570
Thereafter	35,836
Total undiscounted lease payments	60,652
Present value adjustment	26,423
Total net lease liability	34,229
Operating lease liabilities	1,630
Operating lease liabilities	32,599
Total net lease liability	$ 34,229

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Supplemental Disclosure Cash Flow Related to Operating Leases (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Cash flows from operating activities
Cash paid for amounts included in the measurement of lease liabilities	$ 2,727

Commitments and Contingencies_5

Commitments and Contingencies - Schedule of Additional Information Related to Operating Leases (Details)	Jun. 30, 2019
Weighted-average remaining lease terms (in years)
Operating leases	10 years 3 months 25 days
Weighted-average discount rate
Operating leases	12.00%

Common Stock - Schedule of Comm

Common Stock - Schedule of Common Share Reserved for Future Issuance (Details) - shares	Jun. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	20,586,051
Shares available for future stock option grants	8,436,766	7,255,050
Options Issued and Outstanding
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	10,797,308
Restricted Stock Units (RSUs)
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	1,290,260
Common Stock Warrants
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	61,717

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - At-the-Market Offering - 2017 Sales Agreement - Cowen and Company, LLC - USD ($)	1 Months Ended	6 Months Ended	12 Months Ended
	Aug. 31, 2017	Jun. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Commission on sales of common stock, percentage	3.00%
Issuance of common stock (in shares)		0	0
Aggregate offering available for issuance of common stock		$ 81,500,000
Maximum
Class Of Stock [Line Items]
Aggregate offering price from offer and sale of common stock	$ 100,000,000

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details) - USD ($)	Jan. 01, 2019	Feb. 28, 2015	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Apr. 30, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable increased during the period					3,182,868
Number of shares available for future grant			8,436,766		8,436,766		7,255,050
Number of options outstanding			10,797,308		10,797,308		8,986,010
Aggregate intrinsic value of options exercised			$ 400,000		$ 1,100,000
Unrecognized compensation expense			13,500,000		$ 13,500,000
Weighted-average period of unrecognized compensation expense					3 years 1 month 6 days
Expected dividend yield					0.00%
Stock-based compensation related to options granted			3,336,000	$ 4,327,000	$ 7,039,000	$ 9,251,000
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation related to options granted			3,300,000	4,300,000	7,000,000	9,100,000
Non Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation			19,000	$ 100,000	$ 44,000	$ 100,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period of unrecognized compensation expense					2 years 3 months 18 days
Unrecognized stock-based compensation expense related to RSUs			$ 5,700,000		$ 5,700,000
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price to fair market value common stock on grant date					100.00%
Stock option expiration period					10 years
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for issuance								6,134,292
Percentage of shares issued on common stock outstanding					4.00%
Common Stock Issuance Description					shares issuable under the 2015 Plan to the lower of (i) 4% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (ii) a lower number determined by the board of directors.
Shares issuable increased during the period	3,182,868
Number of shares available for future grant			8,436,766		8,436,766
2009 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable increased during the period		360,000
Number of options outstanding			3,013,117		3,013,117
2015 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for issuance								720,000
Percentage of shares issued on common stock outstanding					1.00%
Common Stock Issuance Description					shares issuable under the 2015 ESPP equal to the lower of (i) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (ii) a lower number determined by the board of directors.
Shares issuable increased during the period	0
Number of shares available for future grant			1,622,920		1,622,920
Unrecognized compensation expense			$ 100,000		$ 100,000
Weighted-average period of unrecognized compensation expense					4 months 24 days
More Than 10% Voting Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option expiration period					5 years
More Than 10% Voting Shares | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price to fair market value common stock on grant date					110.00%

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Shares Available for Grant, Beginning balance	7,255,050
Options Outstanding, Shares Available for Grant, Authorized	3,182,868
Options Outstanding, Shares Available for Grant, RSUs forfeited, net of grants	238,552
Options Outstanding, Shares Available for Grant, Granted	(4,617,300)
Options Outstanding, Shares Available for Grant, Canceled	2,377,596
Options Outstanding, Shares Available for Grant, Ending balance	8,436,766
Options Outstanding, Number of Shares Underlying Options, Beginning balance	8,986,010
Options Outstanding, Number of Shares Underlying Options, Granted	4,617,300
Options Outstanding, Number of Shares Underlying Options, Exercised	(428,406)
Options Outstanding, Number of Shares Underlying Options, Canceled	(2,377,596)
Options Outstanding, Number of Shares Underlying Options, Ending balance	10,797,308
Options Outstanding, Number of Shares Underlying Options, Options exercisable	5,444,742
Options Outstanding, Number of Shares Underlying Options, Options vested and expected to vest	9,760,686
Options Outstanding, Weighted-Average Exercise Price, Beginning balance | $ / shares	$ 7.54
Options Outstanding, Weighted-Average Exercise Price, Granted | $ / shares	3.79
Options Outstanding, Weighted-Average Exercise Price, Exercised | $ / shares	1.02
Options Outstanding, Weighted-Average Exercise Price, Canceled | $ / shares	9.63
Options Outstanding, Weighted-Average Exercise Price, Ending balance | $ / shares	5.74
Options Outstanding, Weighted-Average Exercise Price, Options exercisable | $ / shares	6.64
Options Outstanding, Weighted-Average Exercise Price, Options vested and expected to vest | $ / shares	$ 5.88
Options Outstanding, Aggregate Intrinsic Value, Balance | $	$ 1,466	$ 5,458
Options Outstanding, Aggregate Intrinsic Value, Options exercisable-March 31, 2019 | $	1,466
Options Outstanding, Aggregate Intrinsic Value, Options vested and expected to vest-March 31, 2019 | $	$ 1,466

Equity Incentive Plans - Summ_2

Equity Incentive Plans - Summary of Restricted Stock Unit or RSU Activity (Details) - Restricted Stock Units (RSUs)	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Stock Units, Beginning balance | shares	1,600,218
Number of Restricted Stock Units, Granted | shares	275,000
Number of Restricted Stock Units, Vested | shares	(71,406)
Number of Restricted Stock Units, Forfeited | shares	(513,552)
Number of Restricted Stock Units, Ending balance | shares	1,290,260
Weighted-Average Grant Date Fair Value Per Share, Beginning balance | $ / shares	$ 8.81
Weighted-Average Grant Date Fair Value Per Share, Granted | $ / shares	1.74
Weighted-Average Grant Date Fair Value Per Share, Vested | $ / shares	10.17
Weighted-Average Grant Date Fair Value Per Share, Forfeited | $ / shares	8.66
Weighted-Average Grant Date Fair Value Per Share, Ending balance | $ / shares	$ 7.28

Equity Incentive Plans - Schedu

Equity Incentive Plans - Schedule of Black-Scholes Option-Pricing Model (Details)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Employees | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 25 days	5 years 3 months 25 days
Volatility	67.20%	71.60%
Risk-free interest rate	1.96%	2.38%
Employees | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 18 days
Volatility	70.40%	71.70%
Risk-free interest rate	2.40%	2.87%
Non Employees | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 2 months 1 day	6 years 2 months 1 day
Volatility	70.50%	71.60%
Risk-free interest rate	2.66%	2.66%
Non Employees | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	9 years 7 months 28 days	9 years 7 months 6 days
Volatility	70.80%	71.70%
Risk-free interest rate	3.19%	2.94%
2015 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months
Volatility	58.90%	54.50%
Risk-free interest rate	2.43%	2.09%

Equity Incentive Plans - Summ_3

Equity Incentive Plans - Summary of Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 3,336	$ 4,327	$ 7,039	$ 9,251
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,713	2,539	3,746	5,284
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,623	$ 1,788	$ 3,293	$ 3,967

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Contingency [Line Items]
Income tax benefit	$ 35,000	$ 38,000	$ 70,000	$ 59,000
State | Earliest Tax Year
Income Tax Contingency [Line Items]
Open tax year			Dec. 31, 2015
State | Latest Tax Year
Income Tax Contingency [Line Items]
Open tax year			Dec. 31, 2017
U.S. Federal Tax Authority | Earliest Tax Year
Income Tax Contingency [Line Items]
Open tax year			Dec. 31, 2015
U.S. Federal Tax Authority | Latest Tax Year
Income Tax Contingency [Line Items]
Open tax year			Dec. 31, 2017
California Tax Authority
Income Tax Contingency [Line Items]
Tax assessment additional period			5 years

Net Loss per Common Share - Sch

Net Loss per Common Share - Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Per Common Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per common share would be anti-dilutive	12,149,285	10,849,623	12,149,285	10,849,623
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per common share would be anti-dilutive	10,797,308	9,620,114	10,797,308	9,620,114
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per common share would be anti-dilutive	1,290,260	1,165,848	1,290,260	1,165,848
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per common share would be anti-dilutive	61,717	63,661	61,717	63,661