Viracta Therapeutics (VIRX) 10-K 9 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 24, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	SNSS
Entity Registrant Name	SUNESIS PHARMACEUTICALS INC
Entity Central Index Key	1,061,027
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		20,924,522
Entity Public Float			$ 43,332,609

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 8,056	$ 26,886
Marketable securities	34,532	19,544
Prepaids and other current assets	643	558
Total current assets	43,231	46,988
Property and equipment, net	3	14
Total assets	43,234	47,002
Current liabilities:
Accounts payable	1,871	2,453
Accrued clinical expense	1,434	1,954
Accrued compensation	2,000	1,606
Other accrued liabilities	1,691	2,711
Current portion of deferred revenue	610	2,441
Current portion of notes payable	3,333	7,834
Total current liabilities	10,939	18,999
Non-current portion of deferred revenue		610
Non-current portion of notes payable	11,102
Other liabilities	169
Commitments and contingencies (Note 9)
Stockholders’ equity (deficit):
Convertible preferred stock, $0.0001 par value; 10,000 shares authorized as of December 31,2016;18 and 20 shares issued and outstanding as of December 2016 and 2015, respectively	18,808	16,459
Common stock, $0.0001 par value; 400,000 shares authorized as of December 31, 2015; 20,925 and 14,420 shares issued and outstanding as of December 31, 2016 and 2015, respectively	2	1
Additional paid-in capital	599,632	570,317
Accumulated other comprehensive loss	(22)	(11)
Accumulated deficit	(597,396)	(559,373)
Total stockholders’ equity	21,024	27,393
Total liabilities and stockholders’ equity	$ 43,234	$ 47,002

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	18,000	20,000
Preferred stock, shares outstanding	17,897	20,200
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	20,925,000	14,420,000
Common stock, shares outstanding	20,925,000	14,420,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
License and other revenue	$ 2,536	$ 3,061	$ 5,734
Total revenues	2,536	3,061	5,734
Operating expenses:
Research and development	22,881	23,701	27,665
General and administrative	16,115	18,662	23,112
Total operating expenses	38,996	42,363	50,777
Loss from operations	(36,460)	(39,302)	(45,043)
Interest expense	(1,721)	(939)	(1,719)
Other income, net	158	3,565	3,760
Net loss	(38,023)	(36,676)	(43,002)
Unrealized loss on available-for-sale securities	(11)	(4)	(4)
Comprehensive loss	(38,034)	(36,680)	(43,006)
Net loss:
Basic	(38,023)	(36,676)	(43,002)
Diluted	$ (38,023)	$ (36,676)	$ (46,894)
Shares used in computing net loss per common share:
Basic	15,688	12,156	10,010
Diluted	15,688	12,156	10,252
Net loss per common share:
Basic	$ (2.42)	$ (3.02)	$ (4.30)
Diluted	$ (2.42)	$ (3.02)	$ (4.57)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2013	$ (6,184)		$ 1	$ 473,513	$ (3)	$ (479,695)
Beginning Balance, shares at Dec. 31, 2013			9,057
Issuance of common stock and warrants in underwritten offering, net of issuance costs	40,024			40,024
Issuance of common stock and warrants in underwritten offering, net of issuance costs, shares			775
Issuance of common stock through controlled equity offering facilities, net of issuance costs	14,292			14,292
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares			852
Issuance of common stock pursuant to warrant exercises	949			949
Issuance of common stock pursuant to warrant exercises, shares			221
Issuance of common stock pursuant to stock option exercises	1,226			1,226
Issuance of common stock pursuant to stock option exercises, shares			94
Issuance of common stock under employee stock purchase plans	282			282
Issuance of common stock under employee stock purchase plans, shares			17
Issuance of common stock to employees, shares			1
Stock-based compensation expenses—employees	5,882			5,882
Stock-based compensation expenses—non-employees	337			337
Net loss	(43,002)					(43,002)
Unrealized loss on available-for-sale securities	(4)				(4)
Ending Balance at Dec. 31, 2014	13,802		$ 1	536,505	(7)	(522,697)
Ending Balance, shares at Dec. 31, 2014			11,017
Issuance of common stock and warrants in underwritten offering, net of issuance costs	8,709			8,709
Issuance of common stock and warrants in underwritten offering, net of issuance costs, shares			1,833
Issuance of common stock through controlled equity offering facilities, net of issuance costs	18,125			18,125
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares			1,160
Issuance of common stock pursuant to warrant exercises, shares			350
Issuance of common stock pursuant to stock option exercises	331			331
Issuance of common stock pursuant to stock option exercises, shares			28
Issuance of common stock under employee stock purchase plans	202			202
Issuance of common stock under employee stock purchase plans, shares			22
Issuance of common stock to employees, shares			10
Issuance of preferred stock	16,459	$ 16,459
Issuance of preferred stock, shares		20,200
Issuance of warrants to purchase common stock	100			100
Stock-based compensation expenses—employees	6,149			6,149
Stock-based compensation expenses—non-employees	196			196
Net loss	(36,676)					(36,676)
Unrealized loss on available-for-sale securities	(4)				(4)
Ending Balance at Dec. 31, 2015	$ 27,393	$ 16,459	$ 1	570,317	(11)	(559,373)
Ending Balance, shares at Dec. 31, 2015	14,420	20,200	14,420
Issuance of common stock and warrants in underwritten offering, net of issuance costs	$ 20,325		$ 1	20,324
Issuance of common stock and warrants in underwritten offering, net of issuance costs, shares			5,676
Issuance of common stock through controlled equity offering facilities, net of issuance costs	269			269
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares			57
Issuance of common stock upon conversion of preferred stock		$ (3,243)	$ 644	3,243
Issuance of common stock upon conversion of preferred stock, shares		(3,861)	643
Issuance of common stock under employee stock purchase plans	$ 152			152
Issuance of common stock under employee stock purchase plans, shares	59,086		129
Issuance of preferred stock	$ 5,592	$ 5,592
Issuance of preferred stock, shares		1,558
Issuance of warrants to purchase common stock	536			536
Stock-based compensation expenses—employees	4,600			4,600
Stock-based compensation expenses—non-employees	191			191
Net loss	(38,023)					(38,023)
Unrealized loss on available-for-sale securities	(11)				(11)
Ending Balance at Dec. 31, 2016	$ 21,024	$ 18,808	$ 2	$ 599,632	$ (22)	$ (597,396)
Ending Balance, shares at Dec. 31, 2016	20,925	17,897	20,924

CONSOLIDATED STATEMENTS OF STO6

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Stockholders Equity [Abstract]
Issuance of common stock and warrants in underwritten offering	$ 21,852	$ 9,236	$ 43,013
Issuance of common stock and warrants in underwritten offering, issuance costs	1,497	527	2,989
Issuance of common stock through controlled equity offering facilities	269	18,564	14,734
Issuance of common stock through controlled equity offering facilities, issuance costs	$ 5	$ 439	$ 442

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net loss	$ (38,023)	$ (36,676)	$ (43,002)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	4,791	6,345	6,219
Depreciation and amortization	11	27	29
Amortization of debt discount and debt issuance costs	359	135	367
Write-off debt discount upon note repayment	27
Decrease in fair value of warrant liability		(3,543)	(3,892)
Changes in operating assets and liabilities:
Prepaids and other assets	(85)	660	(43)
Accounts payable	(582)	(724)	2,224
Accrued clinical expense	(520)	(1,158)	(1,638)
Accrued compensation	394	(681)	568
Other liabilities	169
Other accrued liabilities	(1,062)	(186)	1,674
Deferred revenue	(2,441)	(2,930)	(5,687)
Net cash used in operating activities	(36,962)	(38,731)	(43,181)
Cash flows from investing activities
Purchases of property and equipment			(48)
Purchases of marketable securities	(35,530)	(35,683)	(42,463)
Sale and maturities of marketable securities	20,531	36,930	45,836
Net cash (used in) provided by investing activities	(14,999)	1,247	3,325
Cash flows from financing activities
Proceeds from notes payable	15,000
Principal payments on notes payable and final payment	(7,983)	(1,642)	(9,356)
Payment of financing fees and debt issuance costs	(266)
Proceeds from issuance of convertible preferred stock offering, net	5,592	16,459
Proceeds from issuance of common stock and warrants	20,367	8,709	40,024
Proceeds from issuance of common stock through controlled equity offering facilities, net	269	18,125	14,292
Proceeds from exercise of warrants, stock options and stock purchase rights	152	533	1,961
Net cash provided by financing activities	33,131	42,184	46,921
Net (decrease) increase in cash and cash equivalents	(18,830)	4,700	7,065
Cash and cash equivalents at beginning of period	26,886	22,186	15,121
Cash and cash equivalents at end of period	8,056	26,886	22,186
Supplemental disclosure of cash flow information
Interest paid	1,239	631	1,221
Supplemental disclosure of non-cash activities
Transfer of fair value of exercised warrants to additional paid-in capital		100	496
Conversion of preferred stock to common stock	(3,243)
Fair value of warrants issued in connection with notes payable	$ 536
Cashless exercise of warrants		$ 4,486	$ 9,337

Company Overview

Company Overview	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview	1. Company Overview Description of Business Sunesis is a biopharmaceutical company focused on the development and commercialization of new oncology therapeutics for the treatment of solid and hematologic cancers. The Company’s primary activities since incorporation have been conducting research and development internally and through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting clinical trials and raising capital. In January 2014, Sunesis announced the expansion of its oncology pipeline through separate global licensing agreements for two preclinical kinase inhibitor programs. The first agreement, with Biogen Idec MA, Inc., “Biogen,” is for global commercial rights to SNS-062, a selective non-covalently binding oral inhibitor of BTK. The second agreement, with Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited, or Takeda, is for global commercial rights to several potential first-in class, pre-clinical inhibitors of the novel target PDK1. In addition, the Company is in a collaboration with Takeda for the development of TAK-580 (formerly MLN2480), an oral pan-RAF inhibitor, for which Takeda is conducting a multi-arm, open-label Phase 1B study in combination with nivolumab, a PD-1 checkpoint inhibitor; TAK-228, an oral mTORC 1/2 inhibitor; alisertib, an oral aurora A kinase inhibitor; and several chemotherapeutic agents, in adult patients with advanced non-hematologic malignancies. Sunesis’ most advanced program is QINPREZO TM In October 2014, the Company announced the results of a Phase 3, multi-national, randomized, double-blind, placebo-controlled trial of vosaroxin in combination with cytarabine in patients with relapsed or refractory AML, or the VALOR trial. The VALOR trial did not meet its primary endpoint of demonstrating a statistically significant improvement in overall survival, but based upon the favorable results of other predefined analyses of the data in November 2014, the Company submitted a letter of intent to the European Medicines Agency (“EMA”) describing its intention to file a marketing authorization application (“MAA”) for marketing authorization of vosaroxin plus cytarabine for the treatment of relapsed or refractory AML. In June 2015, the Company met separately with its Rapporteur and Co-Rapporteur, who are two appointed members of the EMA’s Committee for Medicinal Products for Human Use. Based upon feedback from these meetings, the Company filed an filing in the U.S . Significant Risks and Uncertainties The Company has incurred significant losses and negative cash flows from operations since its inception, and as of December 31, 2016, had cash, cash equivalents and marketable securities totaling $42.6 million and an accumulated deficit of $597.4 million. The Company will need to raise substantial additional capital to pursue a regulatory strategy for the potential commercialization of QINPREZO TM its product candidate for the potential treatment of acute myeloid leukemia, However, the Company does not know whether additional funding will be available on acceptable terms, or at all. If the Company is unable to raise required funding on acceptable terms or at all, it will need to reduce operating expenses, enter into a collaboration or other similar arrangement with respect to development and/or commercialization rights to vosaroxin, outlicense intellectual property rights to vosaroxin or our other development programs, sell unsecured assets, or a combination of the above, or be forced to delay or reduce the scope of our vosaroxin development program, potentially including any regulatory filings related to the VALOR trial, and/or limit or cease our operations. Concentrations of Credit Risk In accordance with its investment policy, the Company invests cash that is not currently being used for operational purposes. The policy allows for the purchase of low risk debt securities issued by: (a) the United States and certain European governments and government agencies, and (b) highly rated banks and corporations, denominated in U.S. dollars, Euros or British pounds, subject to certain concentration limits. The policy limits maturities of securities purchased to no longer than 24 months and the weighted average maturity of the portfolio to 12 months. Management believes these guidelines ensure both the safety and liquidity of any investment portfolio the Company may hold. Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash, cash equivalents and marketable securities. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents and any marketable securities to the extent of the amounts recorded in the balance sheets.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). Reverse Stock Split On September 7, 2016, the Company effected a one-for-six reverse split of its common stock (the "Reverse Split"), as previously authorized and approved at the annual meeting of stockholders on June 7, 2016. As a result of the Reverse Split, every six shares of common stock were combined into one share of common stock. The Reverse Split affected the shares of Company's common stock: (a) outstanding immediately prior to the effective time of the Reverse Split, (b) available for issuance under the Company's equity incentive plans, (c) issuable upon the exercise of outstanding stock options, restricted stock units and warrants and (d) issuable upon conversion of the outstanding Series B Preferred Stock. All share and per-share data in our consolidated financial statements and notes thereto give retroactive effect to the Reverse Split for all periods presented. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net), Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients In August Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern which will require a reporting entity to evaluate, at each annual and interim reporting period, whether there are conditions or events that raise substantial doubt about the reporting entity's ability to continue as a going concern within one year after the date the financial statements are issued and provide related disclosures. Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern In January 2016, the FASB issued ASU No. Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. Leases In March 2016, the FASB issued ASU 2016-06, Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued ASU No. Improvements to Employee Share-Based Payment Accounting In June 2016 Measurement of Credit Losses on Financial Instruments which will require a reporting entity to use a new forward-looking impairment model for most financial assets that generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, credit losses will be recognized as allowances rather than as reductions in amortized cost. The Company will evaluate the guidance and present the impact in its consolidated financial statements at the time of adoption. In August 2016, The FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments and interim periods within those fiscal years with early adoption permitted. The Company elected to early adopt this ASU in the quarter ended September 30, 2016. There have been no changes in our reported statements of cash flows as a result of the adoption of ASU 2016-15. In November 2016, THE FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Sunesis Europe Limited, a United Kingdom corporation, and Sunesis Pharmaceuticals (Bermuda) Ltd., a Bermuda corporation, as well as a Bermuda limited partnership, Sunesis Pharmaceuticals International LP. All intercompany balances and transactions have been eliminated in consolidation. Segment Reporting Management has determined that the Company operates as a single reportable segment. Significant Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s consolidated financial statements and accompanying notes thereto. Actual results could differ materially from these estimates. Estimates, assumptions and judgments made by management include those related to the valuation of equity and related instruments, revenue recognition, stock-based compensation and clinical trial accounting. Cash Equivalents and Marketable Securities The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities. Marketable securities consist of securities with original maturities of greater than three months, which may include U.S. and European government obligations and corporate debt securities. Management determines the appropriate classification of securities at the time of purchase. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income equity The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in other income, net in the statements of operations and comprehensive loss. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are also recorded to other income, net. The cost of securities sold is based on the specific-identification method. Invoices for certain services provided to the Company are denominated in foreign currencies. To manage the risk of future movements in foreign exchange rates that would affect such amounts, the Company may purchase certain European currencies or highly-rated investments denominated in those currencies, subject to similar criteria as for other investments defined in the Company’s investment policy. There is no guarantee that the related gains and losses will substantially offset each other, and the Company may be subject to significant exchange gains or losses as currencies fluctuate from quarter to quarter. To date, the Company has purchased Euros and Euro-denominated obligations of foreign governments and corporate debt. As of December 31, 2016 and December 31, 2015, the Company held investments denominated in Euros with an aggregate fair value of $0.7 million . Fair Value Measurements The Company measures cash equivalents, marketable securities and warrant liabilities at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP: Level 1 - quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date Level 2 - inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly Level 3 - unobservable inputs The Company’s Level 2 valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. The fair value of the Company’s liability for warrants issued in connection with the 2010 Offering (see Note 10) was determined using the Black-Scholes model, which requires inputs such as the expected term of the warrants, share price volatility, expected dividend yield and risk-free interest rate. As some of these inputs are unobservable, and require significant analysis and judgment to measure, these variables are classified as Level 3. The carrying amounts of the Company’s financial instruments, including Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Accounting for Royalty Agreement The payment of $25.0 million by RPI under the Royalty Agreement (see Note 6) is non-refundable, and no revenue participation right payments will be made unless vosaroxin is T , less $3.1 million initially . The fair value of the warrants was recorded to additional paid-in capital. Accounting for Notes Payable The accounting for certain fees and expenses related to the Loan Agreement (see Note 8) is as follows. The facility fee is being accounted for as a debt discount and classified within notes payable on the Company’s balance sheet. The fair value of the warrants issued in connection with the Loan Agreement have been recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. The debt discount is being amortized as interest expense over the term of the loan using the effective interest method. The final payment is being accreted as interest expense over the term of the loans using the effective interest method. The legal fees are being accounted for as deferred debt issuance costs within assets on the Company’s balance sheet and are being amortized as other income, net over the term of the loans using the effective interest method. Accounting for Equity Financing In October 2010, the Company completed the 2010 Offering (see Note 10), in which the Company sold its common stock and warrants to purchase its common stock for aggregate gross proceeds of $15.5 million. Due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements, the warrants are being accounted for as a derivative liability as opposed to permanent equity. Outstanding warrants under this arrangement are revalued to their fair value each period end, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss. Revenue Recognition Revenue arrangements with multiple deliverables are accounted for in accordance with the Financial Accounting Standards Board Accounting Standards Codification, Subtopic 605-25, Multiple-Element Arrangements Non-refundable fees where the Company has no continuing performance obligations are recognized as revenues when collection is reasonably assured. In situations where continuing performance obligations exist, non-refundable fees are deferred and recognized ratably over the projected performance period. Milestone payments from license or collaboration agreements which are substantive and at risk at the time the agreement is executed are recognized upon completion of the applicable milestone event. Royalty revenues, if any, will be recognized based on reported product sales by third-party licensees. Research funding from any future agreement will be recognized as the related research services are performed. Research and Development Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred. Clinical Trial Accounting The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date. Stock-Based Compensation The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods. The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors and related estimated forfeitures. Foreign Currency Transactions that are denominated in a foreign currency are translated into U.S. dollars at the current exchange rate on the transaction date. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates as of each balance sheet date, with gains or losses on foreign exchange recognized in other income, net in the statements of operations and comprehensive loss. Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income, net in the statements of operations and comprehensive loss.

Loss per Common Share

Loss per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Loss per Common Share	3. Loss per Common Share Basic loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per common share is computed by dividing (a) net loss, less any anti-dilutive amounts recorded during the period for the change in the fair value of warrant liabilities, by (b) the weighted-average number of common shares outstanding for the period plus dilutive potential common shares as determined using the treasury stock method for options and warrants to purchase common stock. The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts): Year Ended December 31, 2016 2015 2014 Numerator: Net loss—basic $ (38,023 ) $ (36,676 ) $ (43,002 ) Adjustment for change in fair value of warrant liability — — (3,892 ) Net loss—diluted $ (38,023 ) $ (36,676 ) $ (46,894 ) Denominator: Weighted-average common shares outstanding—basic 15,688 12,156 10,010 Dilutive effect of warrants — — 242 Weighted-average common shares outstanding—diluted 15,688 12,156 10,252 Net loss per common share: Basic $ (2.42 ) $ (3.02 ) $ (4.30 ) Diluted $ (2.42 ) $ (3.02 ) $ (4.57 ) The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands): As of December 31, 2016 2015 2014 Warrants to purchase shares of common stock 218 938 1,496 Convertible preferred stock 4,270 3,353 — Options to purchase shares of common stock 2,697 2,153 1,764 Outstanding securities not included in calculations 7,185 6,444 3,260

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Financial Instruments	4. Financial Instruments Financial Assets The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated, which were comprised solely of available-for-sale marketable securities with remaining contractual maturities of one year or less (in thousands): Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2016 Input Level Cost Gains Losses Value Money market funds Level 1 $ 3,270 $ — $ — $ 3,270 U.S. Treasury securities Level 1 16,029 — (9 ) 16,020 U.S. certificates of deposit Level 1 4,868 — — 4,868 U.S. corporate debt obligations Level 2 11,617 — (11 ) 11,606 U.S. commercial paper Level 2 2,521 — (2 ) 2,519 Total available-for-sale securities 38,305 — (22 ) 38,283 Less amounts classified as cash equivalents (3,751 ) — — (3,751 ) Amounts classified as marketable securities $ 34,554 $ — $ (22 ) $ 34,532 Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2015 Input Level Cost Gains Losses Value Money market funds Level 1 $ 17,200 $ — $ — $ 17,200 U.S. Treasury securities Level 1 1,003 1,003 U.S. certificates of deposit Level 1 5,001 — — 5,001 Debt securities of U.S. government agencies Level 2 4,494 4,494 U.S. corporate debt obligations Level 2 11,660 — (11 ) 11,649 Total available-for-sale securities 39,358 — (11 ) 39,347 Less amounts classified as cash equivalents (19,803 ) — — (19,803 ) Amounts classified as marketable securities $ 19,555 $ — $ (11 ) $ 19,544 The following table summarizes the available-for-sale securities that were in an unrealized loss position as of December 31, 2016, each Gross Unrealized Estimated Fair December 31, 2016 Losses Value U.S. Treasury securities $ (9 ) $ 16,020 U.S. corporate debt obligations (11 ) 11,606 U.S. commercial paper (2 ) 2,519 Total available-for-sale securities in an unrealized loss position $ (22 ) $ 30,145 No significant facts or circumstances have arisen to indicate that there has been any deterioration in the creditworthiness of the issuers of these securities. The gross unrealized losses are not considered to be significant and have generally been for relatively short durations. The Company does not intend to sell these securities before maturity and it is not likely that they will need to be sold prior to the recovery of their amortized cost basis. There were no sales of available-for-sale debt securities in the years ended December 31, 2016, 2015 2014 Financial Liabilities The warrants issued in connection with the 2010 Offering were classified as a liability on the Company’s consolidated balance sheet as of December 31, 2014 due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements. At each balance sheet date, the estimated fair value of the outstanding warrants is determined using the Black-Scholes model and recorded to the balance sheet, with the change in fair value recorded to other income, net in the statements of operations and comprehensive loss , and the fair value of warrant exercises transferred to additional paid-in capital. The Black-Scholes model requires Level 3 inputs such as the expected term of the warrants and share price volatility. These inputs are subjective and generally require significant analysis and judgment to develop. Any changes in these inputs could result in a significantly higher or lower fair value measurement. The following table summarizes the changes in the fair value of the Company’s Level 3 financial liabilities for the periods indicated (in thousands): Warrant Liability Balance as of December 31, 2014 $ 3,543 Change in fair value of warrant liability (3,543 ) Exercise of warrants — Balance as of December 31, 2015 and 2016 $ —

Other Accrued Liabilities

Other Accrued Liabilities	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Other Accrued Liabilities	5. Other Accrued Liabilities Other accrued liabilities as of December 31 were as follows (in thousands): 2016 2015 Accrued outside services $ 1,192 $ 2,011 Accrued professional services 381 644 Other accruals 118 56 Total other accrued liabilities $ 1,691 $ 2,711

Royalty Agreement

Royalty Agreement	12 Months Ended
	Dec. 31, 2016
Revenue Recognition [Abstract]
Royalty Agreement	6. Royalty Agreement In March 2012, the Company entered into a Revenue Participation Agreement (the “Royalty Agreement”), with RPI Finance Trust (“RPI”), an entity related to Royalty Pharma. In September 2012, pursuant to the provisions of the Royalty Agreement, RPI made a $25.0 million cash payment to the Company. The payment, less $3.1 million representing the fair value of the warrants granted under the arrangement, was initially classified as deferred revenue and is being amortized to revenue over the related performance period. Based on the regulatory interactions with the EMA and FDA outlined in Note 1, the Company extended the end date of the estimated performance period through which the balance of deferred revenue will be amortized from September 30, 2016 to March 31, 2017. As a result, the quarterly amortization was adjusted from $0.9 million per quarter to $0.6 million per quarter, commencing with the quarter ended September 30, 2015. Revenue participation right payments will be made to RPI when and if vosaroxin is commercialized, at a rate of 6.75% of net sales of vosaroxin, on a product-by-product and country-by-country basis world-wide through the later of: (a) the expiration of the last to expire of certain specifically identified patents; (b) 10 years from the date of first commercial sale of such product in such country; or (c) the expiration of all applicable periods of data, market or other regulatory exclusivity in such country with respect to such product.

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	7. License Agreements Overview In August 2004, the Company entered into a collaboration agreement with Biogen MA, Inc. (“Biogen”) to discover, develop and commercialize small molecule inhibitors of the human protein Raf kinase, including family members Raf-1, A-Raf, B-Raf and C-Raf (collectively “Raf”) and up to five additional targets that play a role in oncology and immunology indications (the “Biogen OCA”). In connection with the Company’s June 2008 restructuring, the parties agreed to terminate the research obligations and related funding as of June 30, 2008. In March 2011, as part of a series of agreements among the Company, Biogen and Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited, (“Takeda”), the Company entered into: (a) an amended and restated collaboration agreement with Biogen (the “Biogen 1st ARCA”); (b) a license agreement with Takeda (the “Takeda Agreement”); and (c) a termination and transition agreement among the Company, Biogen and Takeda (the “Termination and Transition Agreement”). The Termination and Transition Agreement provided for (a) the termination of Biogen’s exclusive rights under the Biogen OCA to all discovery programs under such agreement other than for small molecule inhibitors of the human protein Bruton’s tyrosine kinase (“BTK”); (b) the permitted assignment to Takeda of all related Company collaboration assets and rights to Raf kinase and the human protein phosphoinositide-dependent kinase-1 (“PDK1”); and (c) the payment of $4.0 million upfront from Takeda to the Company, which was recorded as revenue in March 2011. Biogen Idec The Biogen 1st ARCA amended and restated the Biogen OCA, to provide for the discovery, development and commercialization of small molecule BTK inhibitors. Under this agreement, the Company no longer has research obligations, but licenses granted to Biogen with respect to the research collaboration under the Biogen OCA (other than the licenses transferred to Takeda under the Takeda Agreement) remain in effect. In June 2012, the Company received an event-based payment and recognized as revenue of $1.5 million from Biogen for the advancement of pre-clinical work in connection with the Biogen 1st ARCA. Under this agreement, the Company is eligible to receive up to an additional $58.5 million in pre-commercialization event-based payments related to the development by Biogen of the first two indications for licensed products against the BTK target. The Company is also eligible to receive royalty payments depending on related product sales, if any. In December 2013, the Company entered into a second amended and restated collaboration agreement with Biogen (the “Biogen 2nd ARCA”), to provide the Company with an exclusive worldwide license to develop, manufacture and commercialize SNS-062, a BTK inhibitor synthesized under the Biogen 1st ARCA, solely for oncology indications. The Company may be required to make a $2.5 million milestone payment depending on its development of SNS-062 and royalty payments depending on related product sales of SNS-062. All other of Sunesis’ rights and obligations contained in the Biogen 1st ARCA remain unchanged, except that potential future royalty payments to Sunesis were reduced to equal those amounts due to Biogen for potential future sales of SNS-062. Takeda Under the Takeda Agreement, the Company granted exclusive licenses to products against two oncology targets originally developed under the Biogen OCA, Raf and PDK1, under substantially the same terms as under the Biogen OCA. In January 2014, the Company entered into an amended and restated license agreement with Takeda (the “Amended Takeda Agreement”), to provide the Company with an exclusive worldwide license to develop and commercialize preclinical inhibitors of PDK1. In connection with the , if any With respect to the Raf target product rights that were originally licensed to Takeda under the Takeda Agreement, the Company may in the future receive up to $57.5 million in pre-commercialization event-based payments related to the development by Takeda of the first two indications for each of the licensed products directed against the Raf target and royalty payments depending on related product sales. Takeda is currently conducting a Phase 1 clinical study of an oral investigative drug, TAK-580, which is licensed to them under the Amended Takeda Agreement.

Notes Payable

Notes Payable	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Notes Payable	8. Notes Payable On March 31, 2016, the Company entered into a loan and security agreement (the “Loan Agreement”) with The Company will be required to pay interest on the borrowings under the Loan Agreement at a per annum rate equal to 8.54% plus the then effective one-month U.S. LIBOR rate. Payments under the Loan Agreement are monthly in arrears and interest-only for the first 12-months. Thereafter and until the scheduled maturity date of April 1, 2020, in addition to interest accrued during such period, the monthly payments will include an amount equal to the outstanding principal divided by 36 months, unless the interest only period is extended by a further six months, in which case the amortization period will be 30 months. A final payment equal to 3.75% of the original principal amount borrowed will be due upon maturity or such earlier date specified in the Loan Agreement. If the Company repays all amounts owed under the Loan Agreement prior to the maturity date, the Company will pay a prepayment fee equal to 2.0% of the amount prepaid if the prepayment occurs on or prior to March 31, 2017, 1.0% of the amount prepaid if the prepayment occurs after March 31, 2017 but on or prior to March 31, 2018 and 0.5% of the amount prepaid if the prepayment occurs thereafter. The facility fee and legal fees related to the debt are being accounted for as a debt discount and classified In conjunction with the Loan Agreement, the Lenders were issued five-year warrants to purchase an Pursuant to the Loan Agreement, the Company is bound by a variety of affirmative covenants during the term of the Loan Agreement, including, without limitation, certain information delivery requirements, notice requirements and obligations to maintain certain insurance. Additionally, the Company is bound by certain negative covenants setting forth actions that are not permitted to be taken during the term of the Loan Agreement without the Lenders’ consent, including, without limitation, incurring certain additional indebtedness, making certain asset dispositions, entering into certain mergers, acquisitions or other business combination transactions or incurring any non-permitted lien or other encumbrance on the Company’s assets. Upon the occurrence of an event of default under the Loan Agreement (subject to cure periods for certain events of default), all amounts owed by the Company thereunder would begin to bear interest at a rate that is 5.0% higher than the rate that would otherwise be applicable and may be declared immediately due and payable by the Collateral Agent. Events of default under the Loan Agreement include, among other things, the following: the occurrence of certain bankruptcy events; the failure to make payments under the Loan Agreement when due; the occurrence of a material impairment on the Collateral Agent’s security interest over the collateral, a material adverse change in the business, operations or condition (financial or otherwise) of the Company or material impairment of the prospect of repayment of the obligations under the Loan Agreement; the occurrence of a default under certain other agreements entered into by the Company; the rendering of certain types of judgments against the Company; the revocation of certain government approvals of the Company; any breach by the Company of any covenant (subject to cure periods for certain covenants) made in the Loan Agreement; and the failure of any representation or warranty made by the Company in connection with the Loan Agreement to be correct in all material respects when made. The Collateral Agent, for the benefit of the Lenders, has a perfected security interest in substantially all of the Company’s property, rights and assets, except for intellectual property, to secure the payment of all amounts owed to the Lenders under the Loan Agreement. Upon marketing approval of vosaroxin, the Collateral Agent, for the benefit of the Lenders, will also have a perfected security interest in the Company’s intellectual property rights relating to vosaroxin. Aggregate future minimum payments due under the Loan Facility as of December 31, 2016 Year ending December 31, Total 2017 $ 4,638 2018 5,874 2019 5,407 2020 2,261 Total minimum payments 18,180 Less amount representing interest (3,180 ) Total notes payable as of December 31, 2016 15,000 Less unamortized debt discount and issuance costs (565 ) Less current portion of notes payable (3,333 ) Non-current portion of notes payable $ 11,102

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Commitments The Company’s operating lease obligation s solely ing In January 2014, a lease for 15,378 square feet was entered into with an expiry date of April 30, 2015. In June 2014, the lease was amended to extend the expiration date to June 30, 2015, and to add 6,105 square feet of additional office space within the same building. The lease has been amended in January 2015 and September 2015 to extend the expiration date to December 31, 2016 Aggregate non-cancelable future minimum rental payments under operating leases as of December 31, 2016, were as follows (in thousands): Year Ending December 31, Payments 2017 $ 654 2018 $ 332 Total rental payments $ 986 The Company recognizes rent expense on a straight-line basis. The Company recorded rent expense of $0.6 million, $0.5 Contingencies From time to time, the Company may be involved in legal proceedings, as well as demands, claims and threatened litigation, which arise in the normal course of its business or otherwise. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on the Company’s results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on the Company because of the defense costs, diversion of management resources and other factors. The Company is not currently involved in any material legal proceedings.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity	10. Stockholders’ Equity Preferred Stock The Company has 10,000,000 shares of authorized preferred stock available for issuance in one or more series. Upon issuance, the Company can determine the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. There were 17,897 shares and 20,200 shares of preferred stock outstanding as of December 31, 2016 2015, respectively. These shares are non-voting Series B and Series C Convertible Preferred Stock at a price of $840 and $3,850 per share, respectively. Each share of non-voting Series B is convertible into 166 shares of our common stock (as adjusted for the Reverse Split) and each share of non-voting Series C Stock is convertible into 1000 shares of our common stock, provided that conversion will be prohibited if, as a result, the holder and its affiliates would own more than 9.98% of the total number of shares of our common stock then outstanding . In the event of the Company’s liquidation, dissolution, or winding up, holders of Series B and Series C Stock will receive a payment equal to $0.0001 per share of Series B and Series C Stock before any proceeds are distributed to the holders of Common Stock. Shares of Series B and Series C Stock will generally have no voting rights, except as required by law and except that the consent of holders of a majority of the outstanding Series B and Series C Stock will be required to amend the terms of the Series B and Series C Stock. Shares of the Series B and Series C Stock will not be entitled to receive any dividends, unless and until specifically declared by the Company’s board of directors, and will rank: • senior to all of the Company’s Common Stock; • senior to any class or series of the Company’s capital stock hereafter created specifically ranking by its terms junior to the Series B and Series C Stock; • on parity with any class or series of the Company’s capital stock hereafter created specifically ranking by its terms on parity with the Series B and Series C Stock; • junior to any class or series of the Company’s capital stock hereafter created specifically ranking by its terms senior to the Series B and Series C Stock; in each case, as to distributions of assets upon the Company’s liquidation, dissolution or winding up whether voluntarily or involuntarily. Common Stock Holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company. Subject to the preferences that may be applicable to any outstanding shares of preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared by the Board of Directors. Under the terms of the Loan Agreement with the Lenders, the Company is precluded from paying cash dividends without the prior written consent of the Lenders. Underwritten Offering In December 2015, the Company completed underwritten offering of (i) 1,832,698 shares of its common stock, that included the In October 2016, the Company completed underwritten offering of (i) 5,675,825 shares of its common stock at a price of $3.85 per share, and (ii) 1,558 shares of its non-voting Series C Convertible Preferred Stock (“Series C Stock”) at a price of $3,850.00 per share. Gross proceeds from the sale were $27.9 million and net proceeds were $25.9 million. Each share of non-voting Series C Stock is convertible into 1,000 shares of Sunesis common stock, provided that conversion will be prohibited if, as a result, the holder and its affiliates would own more than 9.98% of the total number of shares of Sunesis common stock then outstanding. Controlled Equity Offerings In August 2011, the Company entered into a Controlled Equity Offering SM During the year ended December 31, 2016, the Company sold an aggregate of 57,000 4.73 0.3 17.9 2010 Offering In October 2010, the Company completed an underwritten offering, pursuant to which the Company issued an aggregate of 1,226,268 shares of common stock and warrants to purchase 613,133 shares of common stock, for aggregate gross proceeds of $15.5 million (the “2010 Offering”). Net proceeds from the sale were $14.2 million, after deducting underwriting discounts and offering expenses. The warrants had an exercise price of $15.12 per share. In October 2015, all outstanding warrants related to the 2010 Offering expired unexercised. Equity Incentive Plans The Company grants options to purchase shares of its common stock primarily to: (i) new employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period, (ii) existing employees with various vesting schedules over three to four years, (iii) new non-employee members of the board of directors, of which 50% of the shares subject to such options become exercisable on each of the first and second anniversary of the vesting commencement date, and (iv) continuing non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period. On March 15, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Equity Incentive Plan (the “2011 Plan”). The 2011 Plan is intended as the successor to and continuation of the Company’s 1998 Stock Plan, 2001 Stock Plan, 2005 Equity Incentive Award Plan and 2006 Employment Commencement Incentive Plan (collectively, the “Prior Plans”). No additional stock awards will be granted under the Prior Plans. The Company initially reserved a total of 1,006,976 shares of common stock for issuance under the 2011 Plan, which is the sum of (i) the 89,967 shares remaining available as of the Effective Date under the Prior Plans, (ii) an additional 733,333 new shares, and (iii) that portion of the 183,676 shares underlying stock options granted and currently outstanding under the Prior Plans that expire or terminate for any reason prior to exercise or settlement or that are forfeited because of the failure to meet a contingency or condition required to vest such shares. The number of shares of common stock available for issuance under the 2011 Plan automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 4.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. On January 1, 2016 and 2015, in accordance with the above, . During the year ended December 31, 2016, options to purchase 777,049 88,411 Employee Stock Purchase Plans On March 5, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Employee Stock Purchase Plan (the “2011 ESPP”). The 2011 ESPP is intended as the successor to the Company’s 2005 Employee Stock Purchase Plan, which was terminated on June 3, 2011. The 2011 ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Eligible employees can purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the common stock at (i) the beginning of a 12-month offering period, or (ii) at the end of one of the two related 6-month purchase periods. No participant in the 2011 ESPP may be issued or transferred shares of common stock valued at more than $25,000 per calendar year. The initial offering under the 2011 ESPP commenced on June 13, 2011 and ended on May 31, 2012. Subsequent commenced or will The Company initially reserved a total of 83,333 shares of common stock for issuance under the 2011 ESPP. The number of shares of common stock available for issuance under the 2011 ESPP automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 1.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. A total of 59,086 6,179 Warrants Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2016 were as follows (in thousands, except per share amounts): Exercise Price Date Issued Shares Per Share Expiration February 2015 10 $ 13.32 February 2020 March 2016 208 $ 3.25 March 2021 Total warrants outstanding and exercisable 218 Reserved Shares Shares of the Company’s common stock reserved for future issuance as of December 31, 2016 Shares Available Total for Future Outstanding Shares Grant Securities Reserved Warrants — 218 218 Convertible preferred stock — 4,270 4,270 Stock option plans 89 2,698 2,787 Employee stock purchase plan 46 — 46 Total reserved shares of common stock 135 7,186 7,321

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation Overview Employee stock-based compensation expense is calculated based on the grant-date fair value of awards ultimately expected to vest, and recognized under the straight-line attribution method, assuming that all stock-based awards will vest. Effective January 1, 2016, the Company has elected to recognize forfeitures as they occur, as permitted by ASU 2016-09, Compensation – Stock Compensation (Topic 718), Improvement to Employee Share-Based Payment Accounting. Refer to Note 2 for further details. In prior periods, the Company estimated forfeitures at time of grant and revised the estimates in subsequent periods if actual forfeitures differed from those estimates. The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands): Year ended December 31, 2016 2015 2014 Research and development $ 1,630 $ 2,856 $ 2,201 General and administrative 2,970 3,292 3,681 Employee stock-based compensation expense 4,600 6,148 5,882 Non-employee stock-based compensation expense 191 196 337 Total stock-based compensation expense $ 4,791 $ 6,344 $ 6,219 Fair Value of Awards The Company determines the fair value of stock-based awards on the grant date using the Black-Scholes model, which is impacted by the Company’s stock price, as well as assumptions regarding a number of highly subjective variables. The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated: Year Ended December 31, 2016 2015 2014 Assumptions: Expected term (years) 5.3 5.2 5.2 Expected volatility 110.0 % 99.9 % 88.1 % Risk-free interest rate 1.9 % 1.7 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % Fair value: Weighted-average estimated grant date fair value per share $ 3.12 $ 6.20 $ 19.10 Options granted to employees (in thousands) 750 531 613 Total estimated grant date fair value (in thousands) $ 2,344 $ 3,294 $ 11,704 The estimated fair value of stock options that vested in the years ended December 31, 2016, 2015 and 201 4 4.6 5.8 2.6 Option Plan Activity The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts): Weighted Weighted Average Average Number Exercise Remaining Aggregate of Price Per Contractual Intrinsic Shares Share Term (Years) Value Outstanding as of December 31, 2015 2,083 $ 18.32 Options granted 777 $ 3.89 Options exercised — — Options forfeited or expired (219 ) $ 25.77 Outstanding as of December 31, 2016 2,641 $ 13.50 6.90 $ 48 Vested and expected to vest as of December 31, 2016 2,641 $ 13.50 6.90 $ 48 Exercisable as of December 31, 2016 1,524 $ 18.23 5.28 $ 12 The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (i.e., the difference between the Company’s closing stock price on the last trading day of the period and the exercise price, multiplied by the number of in-the-money options) that would have been received by option holders if they had exercised all their options on December 31, 2016. The intrinsic value of options exercised during the years ended December 31, 2016, 2015 2014 nil, and Total estimated unrecognized stock-based compensation cost related to unvested stock options was $ 5.3 2.7 Bonus Awards On February 11, 2016, the Compensation Committee of the Company’s Board of Directors approved cash bonuses to certain of the Company’s employees, including its named executive officers, pursuant to the Company’s 2015 Bonus Program. Under the 2015 Bonus Program, each participant was eligible to receive a cash bonus in an amount up to a specified target percentage of such participant’s annual base salary for 2015 based on the level of achievement of certain corporate and individual objectives. The bonus payment amounts approved by the Compensation Committee were based on its determination of the degree to which such corporate and individual objectives were achieved. A portion of the bonuses awarded consisted of 122,000 fully vested shares of the Company’s common stock granted under the 2011 Plan. The stock portion of the bonus awards were granted effective as of February 29, 2016 and the cash portion of the bonus awards were paid on February 29, 2016. The number of shares of the Company’s common stock awarded to Mr. Daniel N. Swisher, Jr., the Company’s CEO and President, and Mr. Eric H. Bjerkholt, the Company’s Executive Vice President, Corporate Development and Finance, Chief Financial Officer and Corporate Secretary, under the 2011 Plan were determined based on the closing price of the Company’s common stock as quoted on the NASDAQ Capital Market on February 29, 2016, rounded down to the nearest whole share. Performance Awards On February 25, 2015, the Compensation Committee of the Board approved equity awards in the form of restricted stock units (“RSUs”) for certain of the Company’s employees (“participant”) under 2011 Stock Incentive Plan. The RSUs have an exercise price of $0 and vesting is subject to the achievement of the earlier of one of two milestones: acceptance of NDA (U.S.) or approval of MAA (EU) and the participant being an employee at time of milestone achievement. As of December 31, 2016, none of the RSUs were vested. The following table summarizes the Company's RSU activity for the year ended December 31, 2016 (in thousands, except per share amounts): Number of Performance based restricted stock units Shares Outstanding as of December 31, 2015 71 Stocks granted — Stocks exercised — Stocks forfeited or expired (15 ) Outstanding as of December 31, 2016 56

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes Loss before the provision for income taxes consisted of the following (in thousands): Year Ended December 31, 2016 2015 2014 U.S. operations $ (26,942 ) $ (23,705 ) $ (32,696 ) Foreign operations (11,081 ) (12,971 ) (10,306 ) Loss before provision for income taxes $ (38,023 ) $ (36,676 ) $ (43,002 ) No provision for income taxes was recorded in the periods presented due to tax losses incurred in each period. The income tax provision differs from the amount computed by applying the statutory income tax rate of 34% to pre-tax loss as follows (in thousands): Year Ended December 31, 2016 2015 2014 Tax at statutory rate $ (12,928 ) $ (12,470 ) $ (14,620 ) Current year net operating losses and temporary differences for which no tax benefit is recognized 9,500 9,596 14,104 Foreign tax rate differential 3,768 4,410 3,504 Deferred revenue (830 ) (996 ) (1,934 ) Change in fair value of warrant liability 0 (1,204 ) (1,313 ) Other permanent differences 490 664 259 Provision for income taxes $ — $ — $ — Deferred income taxes reflect the net tax effects of loss and credit carry-forwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Federal and state net operating loss carry-forwards $ 156,066 $ 147,408 Federal and state research credit carry-forwards 13,177 12,557 Capitalized research costs 4,824 5,119 Deferred revenue 244 1,221 Stock-based compensation 5,739 5,275 Property and equipment 120 127 Accrued liabilities 207 133 Gross deferred tax assets 180,377 171,840 Valuation allowance (180,377 ) (171,840 ) Net deferred tax assets $ — $ — The Company’s unrecognized tax benefits relate to research and development tax credits claimed on the Company’s tax returns. The research and development tax credits have not been utilized, are fully offset by a valuation allowance, and currently have no tax expense impact. A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is follows (in thousands): December 31, 2016 2015 Unrecognized tax benefits at beginning of period $ 1,381 $ — Increases related to prior year tax positions — 1,285 Increases related to current year tax positions 60 96 Unrecognized tax benefits at the end of period $ 1,441 $ 1,381 Realization of the deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The net valuation allowance increased by approximately $8 .5 8.4 14.6 2015 2014 As of December 31, 2016, the Company had federal net operating loss carry-forwards of $ 413.2 9.1 267.1 .0 Utilization of these net operating loss and tax credits carry-forwards may be subject to a substantial annual limitation due to the ownership change rules under Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”). The limitations are applicable if an “ownership change,” as defined in the Code, is deemed to have occurred or occurs in the future. The annual limitation may result in the expiration of net operating loss and credit carry-forwards before they can be utilized. The Company recognizes the financial statement effect of tax positions when it is more likely than not that the tax positions will be sustained upon examination by the appropriate taxing authorities. As of December 31, 2016 and 2015, the Company had unrecognized tax benefits of $1.4 million. The Company did not have any unrecognized tax positions as of December 31, 2014. The Company files U.S. federal and California tax returns. The Company’s wholly owned subsidiaries, Sunesis Europe Limited and Sunesis Pharmaceuticals (Bermuda) Ltd., are currently not required to file tax returns. To date, neither the Company nor any of its subsidiaries have been audited by the Internal Revenue Service, any state income tax authority or tax authority in the related jurisdictions. Due to net operating loss carry-forwards, substantially all of the Company’s tax years remain open to federal tax examination.

Guarantees and Indemnification

Guarantees and Indemnification	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Guarantees and Indemnification	13. Guarantees and Indemnification As permitted under Delaware law and in accordance with the Company’s Bylaws, the Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity. The indemnification agreements with the Company’s officers and directors terminate upon termination of their employment, but the termination does not affect claims for indemnification relating to events occurring prior to the effective date of termination. The maximum amount of potential future indemnification is unlimited; however, the Company’s officer and director insurance policy reduces the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification agreements is minimal. In addition, in the ordinary course of business the Company enters into agreements, such as licensing agreements, clinical trial agreements and certain services agreements, containing standard indemnifications provisions. The Company believes that the likelihood of an adverse judgment related to such indemnification provisions is remote. Accordingly, the Company has not recorded any liabilities for any of these agreements as of December 31, 2016.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events None.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	15. Selected Quarterly Financial Data (unaudited, and in thousands, except per share amounts) The following table sets forth the Company’s unaudited consolidated financial results for the last eight fiscal quarters. Three Months Ended Mar. 31, June 30, Sep. 30, Dec. 31, Mar. 31, June 30, Sep. 30, Dec. 31, 2016 2016 2016 2016 2015 2015 2015 2015 Revenue $ 640 $ 610 $ 610 $ 676 $ 854 $ 854 $ 683 $ 670 Net loss: Basic $ (10,086 ) $ (10,446 ) $ (8,954 ) $ (8,537 ) $ (9,128 ) $ (8,949 ) $ (7,021 ) $ (11,578 ) Diluted $ (10,086 ) $ (10,446 ) $ (8,954 ) $ (8,537 ) $ (9,128 ) $ (10,816 ) $ (7,021 ) $ (11,578 ) Shares used in computing net loss per common share: Basic 14,443 14,493 14,503 19,285 11,274 12,086 12,463 12,781 Diluted 14,443 14,493 14,503 19,285 11,274 12,088 12,463 12,781 Net loss per common share(1): Basic $ (0.70 ) $ (0.72 ) $ (0.62 ) $ (0.44 ) $ (0.81 ) $ (0.12 ) $ (0.56 ) $ (0.91 ) Diluted $ (0.70 ) $ (0.72 ) $ (0.62 ) $ (0.44 ) $ (0.81 ) $ (0.15 ) $ (0.56 ) $ (0.91 ) (1) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarter per-share calculations will not necessarily equal the annual per share calculation.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).
Reverse Stock Split	Reverse Stock Split On September 7, 2016, the Company effected a one-for-six reverse split of its common stock (the "Reverse Split"), as previously authorized and approved at the annual meeting of stockholders on June 7, 2016. As a result of the Reverse Split, every six shares of common stock were combined into one share of common stock. The Reverse Split affected the shares of Company's common stock: (a) outstanding immediately prior to the effective time of the Reverse Split, (b) available for issuance under the Company's equity incentive plans, (c) issuable upon the exercise of outstanding stock options, restricted stock units and warrants and (d) issuable upon conversion of the outstanding Series B Preferred Stock. All share and per-share data in our consolidated financial statements and notes thereto give retroactive effect to the Reverse Split for all periods presented.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net), Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients In August Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern which will require a reporting entity to evaluate, at each annual and interim reporting period, whether there are conditions or events that raise substantial doubt about the reporting entity's ability to continue as a going concern within one year after the date the financial statements are issued and provide related disclosures. Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern In January 2016, the FASB issued ASU No. Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. Leases In March 2016, the FASB issued ASU 2016-06, Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued ASU No. Improvements to Employee Share-Based Payment Accounting In June 2016 Measurement of Credit Losses on Financial Instruments which will require a reporting entity to use a new forward-looking impairment model for most financial assets that generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, credit losses will be recognized as allowances rather than as reductions in amortized cost. The Company will evaluate the guidance and present the impact in its consolidated financial statements at the time of adoption. In August 2016, The FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments and interim periods within those fiscal years with early adoption permitted. The Company elected to early adopt this ASU in the quarter ended September 30, 2016. There have been no changes in our reported statements of cash flows as a result of the adoption of ASU 2016-15. In November 2016, THE FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Sunesis Europe Limited, a United Kingdom corporation, and Sunesis Pharmaceuticals (Bermuda) Ltd., a Bermuda corporation, as well as a Bermuda limited partnership, Sunesis Pharmaceuticals International LP. All intercompany balances and transactions have been eliminated in consolidation.
Segment Reporting	Segment Reporting Management has determined that the Company operates as a single reportable segment.
Significant Estimates and Judgments	Significant Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s consolidated financial statements and accompanying notes thereto. Actual results could differ materially from these estimates. Estimates, assumptions and judgments made by management include those related to the valuation of equity and related instruments, revenue recognition, stock-based compensation and clinical trial accounting.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities. Marketable securities consist of securities with original maturities of greater than three months, which may include U.S. and European government obligations and corporate debt securities. Management determines the appropriate classification of securities at the time of purchase. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income equity The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in other income, net in the statements of operations and comprehensive loss. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are also recorded to other income, net. The cost of securities sold is based on the specific-identification method. Invoices for certain services provided to the Company are denominated in foreign currencies. To manage the risk of future movements in foreign exchange rates that would affect such amounts, the Company may purchase certain European currencies or highly-rated investments denominated in those currencies, subject to similar criteria as for other investments defined in the Company’s investment policy. There is no guarantee that the related gains and losses will substantially offset each other, and the Company may be subject to significant exchange gains or losses as currencies fluctuate from quarter to quarter. To date, the Company has purchased Euros and Euro-denominated obligations of foreign governments and corporate debt. As of December 31, 2016 and December 31, 2015, the Company held investments denominated in Euros with an aggregate fair value of $0.7 million .
Fair Value Measurements	Fair Value Measurements The Company measures cash equivalents, marketable securities and warrant liabilities at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP: Level 1 - quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date Level 2 - inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly Level 3 - unobservable inputs The Company’s Level 2 valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets. The fair value of the Company’s liability for warrants issued in connection with the 2010 Offering (see Note 10) was determined using the Black-Scholes model, which requires inputs such as the expected term of the warrants, share price volatility, expected dividend yield and risk-free interest rate. As some of these inputs are unobservable, and require significant analysis and judgment to measure, these variables are classified as Level 3. The carrying amounts of the Company’s financial instruments, including
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease.
Accounting for Royalty Agreement	Accounting for Royalty Agreement The payment of $25.0 million by RPI under the Royalty Agreement (see Note 6) is non-refundable, and no revenue participation right payments will be made unless vosaroxin is T , less $3.1 million initially . The fair value of the warrants was recorded to additional paid-in capital.
Accounting for Notes Payable	Accounting for Notes Payable The accounting for certain fees and expenses related to the Loan Agreement (see Note 8) is as follows. The facility fee is being accounted for as a debt discount and classified within notes payable on the Company’s balance sheet. The fair value of the warrants issued in connection with the Loan Agreement have been recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. The debt discount is being amortized as interest expense over the term of the loan using the effective interest method. The final payment is being accreted as interest expense over the term of the loans using the effective interest method. The legal fees are being accounted for as deferred debt issuance costs within assets on the Company’s balance sheet and are being amortized as other income, net over the term of the loans using the effective interest method.
Accounting for Equity Financing	Accounting for Equity Financing In October 2010, the Company completed the 2010 Offering (see Note 10), in which the Company sold its common stock and warrants to purchase its common stock for aggregate gross proceeds of $15.5 million. Due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements, the warrants are being accounted for as a derivative liability as opposed to permanent equity. Outstanding warrants under this arrangement are revalued to their fair value each period end, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss.
Revenue Recognition	Revenue Recognition Revenue arrangements with multiple deliverables are accounted for in accordance with the Financial Accounting Standards Board Accounting Standards Codification, Subtopic 605-25, Multiple-Element Arrangements Non-refundable fees where the Company has no continuing performance obligations are recognized as revenues when collection is reasonably assured. In situations where continuing performance obligations exist, non-refundable fees are deferred and recognized ratably over the projected performance period. Milestone payments from license or collaboration agreements which are substantive and at risk at the time the agreement is executed are recognized upon completion of the applicable milestone event. Royalty revenues, if any, will be recognized based on reported product sales by third-party licensees. Research funding from any future agreement will be recognized as the related research services are performed.
Research and Development	Research and Development Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred.
Clinical Trial Accounting	Clinical Trial Accounting The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date.
Stock-Based Compensation	Stock-Based Compensation The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods. The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors and related estimated forfeitures.
Foreign Currency	Foreign Currency Transactions that are denominated in a foreign currency are translated into U.S. dollars at the current exchange rate on the transaction date. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates as of each balance sheet date, with gains or losses on foreign exchange recognized in other income, net in the statements of operations and comprehensive loss.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income, net in the statements of operations and comprehensive loss.

Loss per Common Share (Tables)

Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Computation of Basic and Diluted Loss per Common Share	The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts): Year Ended December 31, 2016 2015 2014 Numerator: Net loss—basic $ (38,023 ) $ (36,676 ) $ (43,002 ) Adjustment for change in fair value of warrant liability — — (3,892 ) Net loss—diluted $ (38,023 ) $ (36,676 ) $ (46,894 ) Denominator: Weighted-average common shares outstanding—basic 15,688 12,156 10,010 Dilutive effect of warrants — — 242 Weighted-average common shares outstanding—diluted 15,688 12,156 10,252 Net loss per common share: Basic $ (2.42 ) $ (3.02 ) $ (4.30 ) Diluted $ (2.42 ) $ (3.02 ) $ (4.57 )
Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share	The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands): As of December 31, 2016 2015 2014 Warrants to purchase shares of common stock 218 938 1,496 Convertible preferred stock 4,270 3,353 — Options to purchase shares of common stock 2,697 2,153 1,764 Outstanding securities not included in calculations 7,185 6,444 3,260

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value of Company's Financial Assets Measured on Recurring Basis	The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated, which were comprised solely of available-for-sale marketable securities with remaining contractual maturities of one year or less (in thousands): Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2016 Input Level Cost Gains Losses Value Money market funds Level 1 $ 3,270 $ — $ — $ 3,270 U.S. Treasury securities Level 1 16,029 — (9 ) 16,020 U.S. certificates of deposit Level 1 4,868 — — 4,868 U.S. corporate debt obligations Level 2 11,617 — (11 ) 11,606 U.S. commercial paper Level 2 2,521 — (2 ) 2,519 Total available-for-sale securities 38,305 — (22 ) 38,283 Less amounts classified as cash equivalents (3,751 ) — — (3,751 ) Amounts classified as marketable securities $ 34,554 $ — $ (22 ) $ 34,532 Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2015 Input Level Cost Gains Losses Value Money market funds Level 1 $ 17,200 $ — $ — $ 17,200 U.S. Treasury securities Level 1 1,003 1,003 U.S. certificates of deposit Level 1 5,001 — — 5,001 Debt securities of U.S. government agencies Level 2 4,494 4,494 U.S. corporate debt obligations Level 2 11,660 — (11 ) 11,649 Total available-for-sale securities 39,358 — (11 ) 39,347 Less amounts classified as cash equivalents (19,803 ) — — (19,803 ) Amounts classified as marketable securities $ 19,555 $ — $ (11 ) $ 19,544
Summary of Available-for-Sale Securities in Unrealized Loss Position	The following table summarizes the available-for-sale securities that were in an unrealized loss position as of December 31, 2016, each Gross Unrealized Estimated Fair December 31, 2016 Losses Value U.S. Treasury securities $ (9 ) $ 16,020 U.S. corporate debt obligations (11 ) 11,606 U.S. commercial paper (2 ) 2,519 Total available-for-sale securities in an unrealized loss position $ (22 ) $ 30,145
Summary of Changes in Fair Value of Company's Level 3 Financial Liabilities	The following table summarizes the changes in the fair value of the Company’s Level 3 financial liabilities for the periods indicated (in thousands): Warrant Liability Balance as of December 31, 2014 $ 3,543 Change in fair value of warrant liability (3,543 ) Exercise of warrants — Balance as of December 31, 2015 and 2016 $ —

Other Accrued Liabilities (Tabl

Other Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Summary of Other Accrued Liabilities	Other accrued liabilities as of December 31 were as follows (in thousands): 2016 2015 Accrued outside services $ 1,192 $ 2,011 Accrued professional services 381 644 Other accruals 118 56 Total other accrued liabilities $ 1,691 $ 2,711

Notes Payable (Tables)

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Facility	Aggregate future minimum payments due under the Loan Facility as of December 31, 2016 Year ending December 31, Total 2017 $ 4,638 2018 5,874 2019 5,407 2020 2,261 Total minimum payments 18,180 Less amount representing interest (3,180 ) Total notes payable as of December 31, 2016 15,000 Less unamortized debt discount and issuance costs (565 ) Less current portion of notes payable (3,333 ) Non-current portion of notes payable $ 11,102

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Aggregate Non-Cancelable Future Minimum Rental Payments under Operating Leases	Aggregate non-cancelable future minimum rental payments under operating leases as of December 31, 2016, were as follows (in thousands): Year Ending December 31, Payments 2017 $ 654 2018 $ 332 Total rental payments $ 986

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Schedule of Warrants to Purchase Shares of Company's Common Stock	Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2016 were as follows (in thousands, except per share amounts): Exercise Price Date Issued Shares Per Share Expiration February 2015 10 $ 13.32 February 2020 March 2016 208 $ 3.25 March 2021 Total warrants outstanding and exercisable 218
Shares of Common Stock Reserved for Future Issuance	Shares of the Company’s common stock reserved for future issuance as of December 31, 2016 Shares Available Total for Future Outstanding Shares Grant Securities Reserved Warrants — 218 218 Convertible preferred stock — 4,270 4,270 Stock option plans 89 2,698 2,787 Employee stock purchase plan 46 — 46 Total reserved shares of common stock 135 7,186 7,321

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards	The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands): Year ended December 31, 2016 2015 2014 Research and development $ 1,630 $ 2,856 $ 2,201 General and administrative 2,970 3,292 3,681 Employee stock-based compensation expense 4,600 6,148 5,882 Non-employee stock-based compensation expense 191 196 337 Total stock-based compensation expense $ 4,791 $ 6,344 $ 6,219
Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted	The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated: Year Ended December 31, 2016 2015 2014 Assumptions: Expected term (years) 5.3 5.2 5.2 Expected volatility 110.0 % 99.9 % 88.1 % Risk-free interest rate 1.9 % 1.7 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % Fair value: Weighted-average estimated grant date fair value per share $ 3.12 $ 6.20 $ 19.10 Options granted to employees (in thousands) 750 531 613 Total estimated grant date fair value (in thousands) $ 2,344 $ 3,294 $ 11,704
Summary of Stock Option Activity for Company's Stock Option Plans	The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts): Weighted Weighted Average Average Number Exercise Remaining Aggregate of Price Per Contractual Intrinsic Shares Share Term (Years) Value Outstanding as of December 31, 2015 2,083 $ 18.32 Options granted 777 $ 3.89 Options exercised — — Options forfeited or expired (219 ) $ 25.77 Outstanding as of December 31, 2016 2,641 $ 13.50 6.90 $ 48 Vested and expected to vest as of December 31, 2016 2,641 $ 13.50 6.90 $ 48 Exercisable as of December 31, 2016 1,524 $ 18.23 5.28 $ 12
Summary of Company's RSU	The following table summarizes the Company's RSU activity for the year ended December 31, 2016 (in thousands, except per share amounts): Number of Performance based restricted stock units Shares Outstanding as of December 31, 2015 71 Stocks granted — Stocks exercised — Stocks forfeited or expired (15 ) Outstanding as of December 31, 2016 56

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Loss before Provision for Income Taxes	Loss before the provision for income taxes consisted of the following (in thousands): Year Ended December 31, 2016 2015 2014 U.S. operations $ (26,942 ) $ (23,705 ) $ (32,696 ) Foreign operations (11,081 ) (12,971 ) (10,306 ) Loss before provision for income taxes $ (38,023 ) $ (36,676 ) $ (43,002 )
Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate	The income tax provision differs from the amount computed by applying the statutory income tax rate of 34% to pre-tax loss as follows (in thousands): Year Ended December 31, 2016 2015 2014 Tax at statutory rate $ (12,928 ) $ (12,470 ) $ (14,620 ) Current year net operating losses and temporary differences for which no tax benefit is recognized 9,500 9,596 14,104 Foreign tax rate differential 3,768 4,410 3,504 Deferred revenue (830 ) (996 ) (1,934 ) Change in fair value of warrant liability 0 (1,204 ) (1,313 ) Other permanent differences 490 664 259 Provision for income taxes $ — $ — $ —
Significant Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands): December 31, 2016 2015 Deferred tax assets: Federal and state net operating loss carry-forwards $ 156,066 $ 147,408 Federal and state research credit carry-forwards 13,177 12,557 Capitalized research costs 4,824 5,119 Deferred revenue 244 1,221 Stock-based compensation 5,739 5,275 Property and equipment 120 127 Accrued liabilities 207 133 Gross deferred tax assets 180,377 171,840 Valuation allowance (180,377 ) (171,840 ) Net deferred tax assets $ — $ —
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is follows (in thousands): December 31, 2016 2015 Unrecognized tax benefits at beginning of period $ 1,381 $ — Increases related to prior year tax positions — 1,285 Increases related to current year tax positions 60 96 Unrecognized tax benefits at the end of period $ 1,441 $ 1,381

Selected Quarterly Financial 32

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data (Unaudited)	The following table sets forth the Company’s unaudited consolidated financial results for the last eight fiscal quarters. Three Months Ended Mar. 31, June 30, Sep. 30, Dec. 31, Mar. 31, June 30, Sep. 30, Dec. 31, 2016 2016 2016 2016 2015 2015 2015 2015 Revenue $ 640 $ 610 $ 610 $ 676 $ 854 $ 854 $ 683 $ 670 Net loss: Basic $ (10,086 ) $ (10,446 ) $ (8,954 ) $ (8,537 ) $ (9,128 ) $ (8,949 ) $ (7,021 ) $ (11,578 ) Diluted $ (10,086 ) $ (10,446 ) $ (8,954 ) $ (8,537 ) $ (9,128 ) $ (10,816 ) $ (7,021 ) $ (11,578 ) Shares used in computing net loss per common share: Basic 14,443 14,493 14,503 19,285 11,274 12,086 12,463 12,781 Diluted 14,443 14,493 14,503 19,285 11,274 12,088 12,463 12,781 Net loss per common share(1): Basic $ (0.70 ) $ (0.72 ) $ (0.62 ) $ (0.44 ) $ (0.81 ) $ (0.12 ) $ (0.56 ) $ (0.91 ) Diluted $ (0.70 ) $ (0.72 ) $ (0.62 ) $ (0.44 ) $ (0.81 ) $ (0.15 ) $ (0.56 ) $ (0.91 ) (1) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarter per-share calculations will not necessarily equal the annual per share calculation.

Company Overview - Additional I

Company Overview - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash, cash equivalents and marketable securities	$ 42,600
Accumulated deficit	$ (597,396)	$ (559,373)
Maturity limits period	24 months
Dollars weighted average maturity limit period	12 months

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Information (Detail)	Sep. 07, 2016	Oct. 31, 2010USD ($)	Dec. 31, 2016USD ($)Segment	Dec. 31, 2015USD ($)	Sep. 30, 2012USD ($)
Significant Accounting Policies [Line Items]
Reverse stock split, ratio	0.1667
Reverse stock split, description			Reverse Split, every six shares of common stock were combined into one share of common stock. The Reverse Split affected the shares of Company's common stock: (a) outstanding immediately prior to the effective time of the Reverse Split, (b) available for issuance under the Company's equity incentive plans, (c) issuable upon the exercise of outstanding stock options, restricted stock units and warrants and (d) issuable upon conversion of the outstanding Series B Preferred Stock. All share and per-share data in our consolidated financial statements and notes thereto give retroactive effect to the Reverse Split for all periods presented.
Number of reportable segment | Segment			1
Fair value of investments denominated in Euros			$ 700,000	$ 700,000
Proceeds from issuance of common stock and warrants in offering gross		$ 15,500,000
Common stock offering period			At the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods.
Royalty Agreement [Member]
Significant Accounting Policies [Line Items]
Revenue participation right payments			$ 25,000,000		$ 25,000,000
Fair value of warrants issued in connection with participation agreement			3,100,000
Controlled Equity Offering Facilities [Member]
Significant Accounting Policies [Line Items]
Common stock available for sale			$ 17,900,000
Employee Stock Purchase Plan [Member]
Significant Accounting Policies [Line Items]
Purchase price of a share as a percentage of fair market value			85.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets			5 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets			3 years
ASU No. 2014-15 [Member] | Maximum [Member] | Controlled Equity Offering Facilities [Member]
Significant Accounting Policies [Line Items]
Common stock available for sale			$ 17,900,000

Loss per Common Share - Computa

Loss per Common Share - Computation of Basic and Diluted Loss per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net loss—basic	$ (8,537)		$ (8,954)		$ (10,446)		$ (10,086)		$ (11,578)		$ (7,021)		$ (8,949)		$ (9,128)		$ (38,023)	$ (36,676)	$ (43,002)
Adjustment for change in fair value of warrant liability																			(3,892)
Net loss—diluted	$ (8,537)		$ (8,954)		$ (10,446)		$ (10,086)		$ (11,578)		$ (7,021)		$ (10,816)		$ (9,128)		$ (38,023)	$ (36,676)	$ (46,894)
Denominator:
Weighted-average common shares outstanding—basic	19,285		14,503		14,493		14,443		12,781		12,463		12,086		11,274		15,688	12,156	10,010
Dilutive effect of warrants																			242
Weighted-average common shares outstanding—diluted	19,285		14,503		14,493		14,443		12,781		12,463		12,088		11,274		15,688	12,156	10,252
Net loss per common share:
Basic	$ (0.44)	[1]	$ (0.62)	[1]	$ (0.72)	[1]	$ (0.70)	[1]	$ (0.91)	[1]	$ (0.56)	[1]	$ (0.12)	[1]	$ (0.81)	[1]	$ (2.42)	$ (3.02)	$ (4.30)
Diluted	$ (0.44)	[1]	$ (0.62)	[1]	$ (0.72)	[1]	$ (0.70)	[1]	$ (0.91)	[1]	$ (0.56)	[1]	$ (0.15)	[1]	$ (0.81)	[1]	$ (2.42)	$ (3.02)	$ (4.57)
[1]	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarter per-share calculations will not necessarily equal the annual per share calculation.

Loss per Common Share - Schedul

Loss per Common Share - Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	7,185	6,444	3,260
Warrants to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	218	938	1,496
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	4,270	3,353
Options to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	2,697	2,153	1,764

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	$ 38,305	$ 39,358
Available-for-sale securities, Gross Unrealized Losses	(22)	(11)
Available-for-sale securities, Estimated Fair Value	38,283	39,347
Less amounts classified as cash equivalents, Amortized Cost	(3,751)	(19,803)
Amounts classified as marketable securities, Amortized Cost	34,554	19,555
Amounts classified as marketable securities, Gross Unrealized Losses	(22)	(11)
Less amounts classified as cash equivalents, Estimated Fair Value	(3,751)	(19,803)
Amounts classified as marketable securities, Estimated Fair Value	34,532	19,544
Level 1 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	3,270	17,200
Available-for-sale securities, Estimated Fair Value	3,270	17,200
Level 1 [Member] | U.S. Treasury securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	16,029	1,003
Available-for-sale securities, Gross Unrealized Losses	(9)
Available-for-sale securities, Estimated Fair Value	16,020	1,003
Level 1 [Member] | U.S. certificates of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	4,868	5,001
Available-for-sale securities, Estimated Fair Value	4,868	5,001
Level 2 [Member] | Debt securities of U.S. government agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		4,494
Available-for-sale securities, Estimated Fair Value		4,494
Level 2 [Member] | U.S. corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	11,617	11,660
Available-for-sale securities, Gross Unrealized Losses	(11)	(11)
Available-for-sale securities, Estimated Fair Value	11,606	$ 11,649
Level 2 [Member] | U.S. commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	2,521
Available-for-sale securities, Gross Unrealized Losses	(2)
Available-for-sale securities, Estimated Fair Value	$ 2,519

Financial Instruments - Summary

Financial Instruments - Summary of Available-for-Sale Securities in Unrealized Loss Position (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	$ (22)
Estimated Fair Value	30,145
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	(9)
Estimated Fair Value	16,020
U.S. corporate debt obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	(11)
Estimated Fair Value	11,606
U.S. commercial paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	(2)
Estimated Fair Value	$ 2,519

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Sales of available-for-sale securities	$ 0	$ 0	$ 0

Financial Instruments - Summa40

Financial Instruments - Summary of Changes in Fair Value of Company's Level 3 Financial Liabilities (Detail) - Warrant Liability [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Beginning Balance	$ 3,543
Change in fair value of warrant liability upon expiration of warrants	$ (3,543)

Other Accrued Liabilities - Sum

Other Accrued Liabilities - Summary of Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued outside services	$ 1,192	$ 2,011
Accrued professional services	381	644
Other accruals	118	56
Total other accrued liabilities	$ 1,691	$ 2,711

Royalty Agreement - Additional

Royalty Agreement - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2016	Sep. 30, 2012
Royalty Agreement [Line Items]
Deferred revenue, amortized	$ 0.6	$ 0.9
Revenue participation right payments, rate			6.75%
Revenue participation right payments, term			10 years from the date of first commercial sale
Maximum term of revenue participation right payments			10 years
Royalty Agreement [Member]
Royalty Agreement [Line Items]
Revenue participation right payments			$ 25	$ 25
Fair value of warrants issued in connection with participation agreement			$ 3.1

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2014	Dec. 31, 2013	Jun. 30, 2012	Mar. 31, 2011	Dec. 31, 2016
License Agreement Terms [Member] | Takeda License Agreements [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization payments receivable					$ 57.5
Upfront fee paid	$ 0.4
Potential pre-commercialization milestone payments payable	$ 9.2
Biogen And Takeda [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Non refundable upfront amount recognized as revenue due to no further performance obligation				$ 4
Biogen [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Received and recognized milestone revenue			$ 1.5
Biogen [Member] | License Agreement Terms [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization payments receivable			$ 58.5
Biogen [Member] | Development Events [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment depending on development		$ 2.5

Notes Payable - Additional Info

Notes Payable - Additional Information (Detail) - USD ($)	Apr. 01, 2016	Mar. 31, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Proceeds from notes payable			$ 15,000,000
Loan Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 15,000,000
Proceeds from notes payable	$ 2,500,000	12,500,000
Date of Loan and Security Agreement			Oct. 18, 2011
Loan proceeds to repay the outstanding principal		7,200,000
Repayment of outstanding principal		6,000,000
Final payment fee		1,200,000
Accrued interest		45,000
Facility fee		100,000
Legal fees		$ 100,000
Description of monthly interest payment			Payments under the Loan Agreement are monthly in arrears and interest-only for the first 12-months. Thereafter and until the scheduled maturity date of April 1, 2020, in addition to interest accrued during such period, the monthly payments will include an amount equal to the outstanding principal divided by 36 months, unless the interest only period is extended by a further six months, in which case the amortization period will be 30 months.
Line of credit facility final payment percentage			3.75%
Percentage of penalty for prepaying loan before maturity			2.00%
Prepayment penalty expiration date			Mar. 31, 2017
Percentage of penalty for prepaying loan after maturity			0.50%
Maturity date			Apr. 1, 2020
Warrants Expiration Term			5 years
Number of warrants issued			208,002
Warrants exercise price for shares			$ 3.2454
Estimated fair value of warrants issued			$ 500,000
Loan, Covenant description			Pursuant to the Loan Agreement, the Company is bound by a variety of affirmative covenants during the term of the Loan Agreement, including, without limitation, certain information delivery requirements, notice requirements and obligations to maintain certain insurance. Additionally, the Company is bound by certain negative covenants setting forth actions that are not permitted to be taken during the term of the Loan Agreement without the Lenders’ consent, including, without limitation, incurring certain additional indebtedness, making certain asset dispositions, entering into certain mergers, acquisitions or other business combination transactions or incurring any non-permitted lien or other encumbrance on the Company’s assets. Upon the occurrence of an event of default under the Loan Agreement (subject to cure periods for certain events of default), all amounts owed by the Company thereunder would begin to bear interest at a rate that is 5.0% higher than the rate that would otherwise be applicable and may be declared immediately due and payable by the Collateral Agent. Events of default under the Loan Agreement include, among other things, the following: the occurrence of certain bankruptcy events; the failure to make payments under the Loan Agreement when due; the occurrence of a material impairment on the Collateral Agent’s security interest over the collateral, a material adverse change in the business, operations or condition (financial or otherwise) of the Company or material impairment of the prospect of repayment of the obligations under the Loan Agreement; the occurrence of a default under certain other agreements entered into by the Company; the rendering of certain types of judgments against the Company; the revocation of certain government approvals of the Company; any breach by the Company of any covenant (subject to cure periods for certain covenants) made in the Loan Agreement; and the failure of any representation or warranty made by the Company in connection with the Loan Agreement to be correct in all material respects when made.
Loan Agreement [Member] | Warrants to purchase shares of common stock [Member]
Debt Instrument [Line Items]
Common stock price			$ 3.24
Exercise price			$ 3.2454
Risk-free interest rates			1.21%
Expected volatility			111.96%
Expected term			5 years
Dividend yield			0.00%
Loan Agreement [Member] | Extension of Maturity Date [Member]
Debt Instrument [Line Items]
Percentage of penalty for prepaying loan before maturity			1.00%
Prepayment penalty expiration date			Mar. 31, 2018
Loan Agreement [Member] | LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage			8.54%

Notes Payable - Summary of Futu

Notes Payable - Summary of Future Minimum Payments Under Loan Facility (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total notes payable as of December 31, 2016	$ 15,000
Less current portion of notes payable	(3,333)	$ (7,834)
Non-current portion of notes payable	11,102
Notes payable [Member]
Debt Instrument [Line Items]
2,017	4,638
2,018	5,874
2,019	5,407
2,020	2,261
Total minimum payments	18,180
Less amount representing interest	(3,180)
Less unamortized debt discount and issuance costs	$ (565)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)ft²	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Commitments And Contingencies Disclosure [Line Items]
Rent expense | $	$ 0.6	$ 0.5	$ 0.4
Original Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease, office space leased	15,378
Operating lease expiration date	Apr. 30, 2015
Operating lease agreement, original date	2014-01
Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease, additional office space leased	6,105
Operating lease expiration date	Jun. 30, 2015
Operating lease agreement, date of amendment	2014-06
Lease property description	The lease has been amended in January 2015 and September 2015 to extend the expiration date to December 31, 2016 and in September 2016, respectively and in May 2016, the lease was again amended to extend the expiration date to June 30, 2018.
Second Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease expiration date	Dec. 31, 2016
Operating lease agreement, date of amendment	2015-01
Further Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease expiration date	Sep. 30, 2016
Operating lease agreement, date of amendment	2015-09
Fourth Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease expiration date	Jun. 30, 2018
Operating lease agreement, date of amendment	2016-05

Commitments and Contingencies47

Commitments and Contingencies - Aggregate Non-Cancelable Future Minimum Rental Payments under Operating Leases (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,017	$ 654
2,018	332
Total rental payments	$ 986

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information 1 (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended
	Oct. 31, 2016	Dec. 31, 2015	Apr. 30, 2013	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2013	Aug. 31, 2011
Stockholders Equity [Line Items]
Preferred stock, shares authorized		10,000,000		10,000,000
Preferred stock, shares outstanding		20,200		17,897
Common stock, voting rights				One vote per share
Shares of common stock issued		14,420,000		20,925,000
Preferred stock, shares issued		20,000		18,000
Proceeds from issuance of common shares, gross	$ 27.9	$ 26.2
Proceeds from issuance of common stock through controlled equity offering facilities, net	$ 25.9	$ 25.2
Common Stock [Member]
Stockholders Equity [Line Items]
Shares of common stock issued		14,420,000		20,924,000	11,017,000	9,057,000
Underwritten Offering [Member]
Stockholders Equity [Line Items]
Price per common share	$ 3.85	$ 5.04
Shares of common stock issued	5,675,825	1,832,698
Over-Allotment Option [Member]
Stockholders Equity [Line Items]
Shares of common stock issued		239,047
Controlled Equity Offering Facilities [Member]
Stockholders Equity [Line Items]
Proceeds from issuance of common shares, gross				$ 0.3
Proceeds from issuance of common stock through controlled equity offering facilities, net				$ 0.3
Issuance of common stock, offering value							$ 20
Common stock sales agreement, date				2011-08
Issuance of common stock, remaining offering value				$ 17.9
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Price per common share				$ 4.73
Common stock, shares sold				57,000
Additional Controlled Equity Offerings Facilities [Member]
Stockholders Equity [Line Items]
Increase in aggregate controlled equity offering agreement as per amendment			$ 30
Issuance of common stock, commission percentage			3.00%
Common stock sales agreement amended, date				2013-04
Series B and Series C Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share		$ 3,850		$ 840
Preferred stock, payment to stock holders in the event of liquidation, dissolution or winding up preference per share				$ 0.0001
Preferred stock, voting rights				Shares of Series B and Series C Stock will generally have no voting rights, except as required by law and except that the consent of holders of a majority of the outstanding Series B and Series C Stock will be required to amend the terms of the Series B and Series C Stock.
Series B and Series C Convertible Preferred Stock [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock				9.98%
Series B Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share		$ 840
Shares issued upon conversion		166		166
Preferred stock, shares issued		20,200
Series B Convertible Preferred Stock [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock		9.98%
Series C Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share	$ 3,850
Shares issued upon conversion	1,000			1,000
Preferred stock, shares issued	1,558
Series C Convertible Preferred Stock [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock	9.98%

Stockholders' Equity - Additi49

Stockholders' Equity - Additional Information 2 (Detail) - USD ($) $ / shares in Units, $ in Millions	Jan. 02, 2016	Jan. 02, 2015	Jun. 03, 2011	Oct. 31, 2010	Dec. 31, 2016	Dec. 31, 2015
Stockholders Equity [Line Items]
Shares of common stock issued					20,925,000	14,420,000
Total warrants outstanding, shares					218,000
Proceeds from issuance of common stock and warrants in offering gross				$ 15.5
Number of shares of common stock reserved for issuance under latest plan					7,321,000
Shares Available for Future Grant					135,000
Options granted, Number of Shares					777,000
Stock Option Plans [Member]
Stockholders Equity [Line Items]
Number of shares of common stock reserved for issuance under latest plan					2,787,000
Shares Available for Future Grant					89,000
Stock Option Plans [Member] | New Employees [Member]
Stockholders Equity [Line Items]
Option exercisable on first anniversary of vesting commencement date, percent					25.00%
Portion of option exercisable for each month over vesting percent					2.083%
Stock option plans, vesting period					4 years
Vesting rights					New employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period
Stock Option Plans [Member] | Existing Employees [Member]
Stockholders Equity [Line Items]
Vesting rights					Existing employees with various vesting schedules over three to four years
Stock Option Plans [Member] | Existing Employees [Member] | Minimum [Member]
Stockholders Equity [Line Items]
Stock option plans, vesting period					3 years
Stock Option Plans [Member] | Existing Employees [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Stock option plans, vesting period					4 years
Stock Option Plans [Member] | New Non-Employee Board Members [Member]
Stockholders Equity [Line Items]
Stock option plans, vesting period					2 years
Vesting rights					New non-employee members of the board of directors, of which 50% of the shares subject to such options become exercisable on each of the first and second anniversary of the vesting commencement date
Option exercisable on first and second anniversary of vesting commencement date, percent					50.00%
Stock Option Plans [Member] | Continuing Non-Employee Board Members [Member]
Stockholders Equity [Line Items]
Portion of option exercisable for each month over vesting percent					4.166%
Stock option plans, vesting period					2 years
Vesting rights					Continuing non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period
2010 Offering [Member]
Stockholders Equity [Line Items]
Shares of common stock issued				1,226,268
Total warrants outstanding, shares				613,133
Proceeds from issuance of common stock and warrants in offering gross				$ 15.5
Proceeds from issuance of common shares and warrants in offering, net				$ 14.2
Warrants, maturity date				2015-10
Warrants, exercise price per share				$ 15.12
2011 Plan [Member]
Stockholders Equity [Line Items]
Number of shares of common stock reserved for issuance under latest plan			1,006,976
Shares Available for Future Grant			89,967		88,411
Shares of common stock available for issuance	576,785	440,679	733,333
Common stock available for issuance automatic increase period					10 years
Common stock available for issuance automatic increase maximum number of shares					4.00%
Options granted, Number of Shares					777,049
2011 Plan [Member] | Stock Option Plans [Member]
Stockholders Equity [Line Items]
Shares Available for Future Grant			183,676

Stockholders' Equity - Additi50

Stockholders' Equity - Additional Information 3 (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)PurchasePeriodshares
Stockholders Equity [Line Items]
Share of common stock value | $	$ 25,000
Number of shares issued under employee stock purchase plan	59,086,000
Shares Available for Future Grant	135,000
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Purchase price of a share as a percentage of fair market value	85.00%
Duration of offering period	12 months
Number of purchase periods in each offering period | PurchasePeriod	2
Duration of each purchase period	6 months
Number of shares authorized under employee stock purchase plan	83,333
Common stock available for issuance automatic increase period	10 years
Common stock available for issuance automatic increase maximum number of shares	1.00%
Shares Available for Future Grant	46,179

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Warrants to Purchase Shares of Company's Common Stock (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	218
February 2015 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	10
Warrants, Exercise Price Per Share | $ / shares	$ 13.32
Warrants Expiration Date	2020-02
March 2016 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	208
Warrants, Exercise Price Per Share | $ / shares	$ 3.25
Warrants Expiration Date	2021-03

Stockholders' Equity - Shares o

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2016shares
Class of Stock [Line Items]
Shares Available for Future Grant	135,000
Outstanding Securities	7,186,000
Total Shares Reserved	7,321,000
Warrants [Member]
Class of Stock [Line Items]
Outstanding Securities	218,000
Total Shares Reserved	218,000
Stock Option Plans [Member]
Class of Stock [Line Items]
Shares Available for Future Grant	89,000
Outstanding Securities	2,698,000
Total Shares Reserved	2,787,000
Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Shares Available for Future Grant	46,179
Total Shares Reserved	46,000
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Outstanding Securities	4,270,000
Total Shares Reserved	4,270,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 4,791	$ 6,344	$ 6,219
Employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	4,600	6,148	5,882
Non-employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	191	196	337
Research and development [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	1,630	2,856	2,201
General and administrative [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 2,970	$ 3,292	$ 3,681

Stock-Based Compensation - Su54

Stock-Based Compensation - Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assumptions:
Expected dividend yield	0.00%
Fair value:
Options granted to employees (in thousands)	777
Stock Option Plans [Member]
Assumptions:
Expected term (years)	5 years 3 months 18 days	5 years 2 months 12 days	5 years 2 months 12 days
Expected volatility	110.00%	99.90%	88.10%
Risk-free interest rate	1.90%	1.70%	1.70%
Expected dividend yield	0.00%	0.00%	0.00%
Fair value:
Weighted-average estimated grant date fair value per share	$ 3.12	$ 6.20	$ 19.10
Stock Option Plans [Member] | Employee stock-based compensation expense [Member]
Fair value:
Options granted to employees (in thousands)	750	531	613
Total estimated grant date fair value (in thousands)	$ 2,344	$ 3,294	$ 11,704

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Feb. 11, 2016	Feb. 25, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated fair value of stock options, vested			$ 4,600,000	$ 5,800,000	$ 2,600,000
Payment of cash dividends			$ 0
Dividend yield ratio			0.00%
Intrinsic value of options exercised			$ 0	$ 200,000	$ 2,700,000
Tax benefits related to stock option exercised			0
Unrecognized stock-based compensation cost related to unvested stock options			$ 5,300,000
Weighted average term of unrecognized stock-based compensation expense			2 years 8 months 12 days
Performance Based Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price per share		$ 0
Number of RSUs vested			0
2011 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock awards vested	122,000

Stock-Based Compensation - Su56

Stock-Based Compensation - Summary of Stock Option Activity for Company's Stock Option Plans (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Beginning Balance, Number of Shares | shares	2,083
Options granted, Number of Shares | shares	777
Options forfeited or expired, Number of Shares | shares	(219)
Outstanding, Ending Balance, Number of Shares | shares	2,641
Vested and expected to vest as of December 31, 2016, Number of Shares | shares	2,641
Exercisable as of December 31, 2016, Number of Shares | shares	1,524
Outstanding, Beginning Balance, Weighted Average Exercise Price Per Share | $ / shares	$ 18.32
Options granted, Weighted Average Exercise Price Per Share | $ / shares	3.89
Options forfeited or expired, Weighted Average Exercise Price Per Share | $ / shares	25.77
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share | $ / shares	13.50
Vested and expected to vest as of December 31, 2016, Weighted Average Exercise Price Per Share | $ / shares	13.50
Exercisable as of December 31, 2016, Weighted Average Exercise Price Per Share | $ / shares	$ 18.23
Outstanding, Weighted Average Remaining Contractual Term (Years)	6 years 8 months 5 days
Vested and expected to vest as of December 31, 2016, Weighted Average Remaining Contractual Term (Years)	6 years 10 months 24 days
Exercisable as of December 31, 2016, Weighted Average Remaining Contractual Term (Years)	5 years 3 months 11 days
Outstanding, Aggregated Intrinsic Value | $	$ 48
Vested and expected to vest as of December 31, 2016, Aggregate Intrinsic Value | $	48
Ending Balance, Exercisable, Aggregate Intrinsic Value | $	$ 12

Stock-Based Compensation - Su57

Stock-Based Compensation - Summary of Company's RSU (Detail) - Performance Based Restricted Stock Units [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2016shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Beginning Balance, Number of Shares	71
Stocks forfeited or expired, Number of Shares	(15)
Outstanding, Ending Balance, Number of Shares	56

Income Taxes - Loss before Prov

Income Taxes - Loss before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. operations	$ (26,942)	$ (23,705)	$ (32,696)
Foreign operations	(11,081)	(12,971)	(10,306)
Loss before provision for income taxes	$ (38,023)	$ (36,676)	$ (43,002)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Income tax provision	$ 0	$ 0	$ 0
Statutory income tax rate	34.00%
Unrecognized tax benefits that would have tax impact		0
Net valuation allowance increased	$ 8,500,000	8,400,000	14,600,000
Unrecognized tax benefit	1,441,000	$ 1,381,000	$ 0
Domestic tax authority [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	413,200,000
Research and development tax credit carry-forwards	$ 9,100,000
Net operating loss carry-forwards expiration	2,018
State and local jurisdiction [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	$ 267,100,000
Research and development tax credit carry-forwards	8,000,000
Net operating losses expired	$ 38,200,000

Income Taxes - Income Tax Provi

Income Taxes - Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ (12,928,000)	$ (12,470,000)	$ (14,620,000)
Current year net operating losses and temporary differences for which no tax benefit is recognized	9,500,000	9,596,000	14,104,000
Foreign tax rate differential	3,768,000	4,410,000	3,504,000
Deferred revenue	(830,000)	(996,000)	(1,934,000)
Change in fair value of warrant liability	0	(1,204,000)	(1,313,000)
Other permanent differences	490,000	664,000	259,000
Provision for income taxes	$ 0	$ 0	$ 0

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Federal and state net operating loss carry-forwards	$ 156,066	$ 147,408
Federal and state research credit carry-forwards	13,177	12,557
Capitalized research costs	4,824	5,119
Deferred revenue	244	1,221
Stock-based compensation	5,739	5,275
Property and equipment	120	127
Accrued liabilities	207	133
Gross deferred tax assets	180,377	171,840
Valuation allowance	$ (180,377)	$ (171,840)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of period	$ 1,381	$ 0
Increases related to prior year tax positions		1,285
Increases related to current year tax positions	60	96
Unrecognized tax benefits at the end of period	$ 1,441	$ 1,381

Guarantee and Indemnification -

Guarantee and Indemnification - Additional Information (Detail)	Dec. 31, 2016USD ($)
Guarantees [Abstract]
Liabilities incurred in indemnification agreements	$ 0

Selected Quarterly Financial 64

Selected Quarterly Financial Data - Schedule of Quarterly Financial Data (Unaudited) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenue	$ 676		$ 610		$ 610		$ 640		$ 670		$ 683		$ 854		$ 854		$ 2,536	$ 3,061	$ 5,734
Net loss:
Basic	(8,537)		(8,954)		(10,446)		(10,086)		(11,578)		(7,021)		(8,949)		(9,128)		(38,023)	(36,676)	(43,002)
Diluted	$ (8,537)		$ (8,954)		$ (10,446)		$ (10,086)		$ (11,578)		$ (7,021)		$ (10,816)		$ (9,128)		$ (38,023)	$ (36,676)	$ (46,894)
Shares used in computing net loss per common share:
Basic	19,285		14,503		14,493		14,443		12,781		12,463		12,086		11,274		15,688	12,156	10,010
Diluted	19,285		14,503		14,493		14,443		12,781		12,463		12,088		11,274		15,688	12,156	10,252
Net loss per common share:
Basic	$ (0.44)	[1]	$ (0.62)	[1]	$ (0.72)	[1]	$ (0.70)	[1]	$ (0.91)	[1]	$ (0.56)	[1]	$ (0.12)	[1]	$ (0.81)	[1]	$ (2.42)	$ (3.02)	$ (4.30)
Diluted	$ (0.44)	[1]	$ (0.62)	[1]	$ (0.72)	[1]	$ (0.70)	[1]	$ (0.91)	[1]	$ (0.56)	[1]	$ (0.15)	[1]	$ (0.81)	[1]	$ (2.42)	$ (3.02)	$ (4.57)
[1]	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarter per-share calculations will not necessarily equal the annual per share calculation.