Viracta Therapeutics (VIRX) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	SNSS
Entity Registrant Name	SUNESIS PHARMACEUTICALS INC
Entity Central Index Key	1,061,027
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		34,248,322

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents		$ 7,947	$ 8,056	[1]
Marketable securities		4,506	34,532	[1]
Prepaids and other current assets		1,258	643	[1]
Total current assets		13,711	43,231	[1]
Property and equipment, net		22	3	[1]
Other assets		1,335
Total assets		15,068	43,234	[1]
Current liabilities:
Accounts payable		1,541	1,871	[1]
Accrued clinical expense		765	1,434	[1]
Accrued compensation		1,581	2,000	[1]
Other accrued liabilities		1,056	1,691	[1]
Current portion of deferred revenue	[1]		610
Current portion of notes payable		2,500	3,333	[1]
Total current liabilities		7,443	10,939	[1]
Non-current portion of notes payable		4,652	11,102	[1]
Other accrued liabilities		68	169	[1]
Commitments				[1]
Stockholders’ equity:
Convertible preferred stock		16,540	18,808	[1]
Common stock		2	2	[1]
Additional paid-in capital		612,595	599,632	[1]
Accumulated other comprehensive loss		(1)	(22)	[1]
Accumulated deficit		(626,231)	(597,396)	[1]
Total stockholders’ equity		2,905	21,024	[1]
Total liabilities and stockholders’ equity		$ 15,068	$ 43,234	[1]
[1]	The condensed consolidated balance sheet as of December 31, 2016, has been derived from the audited financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue:
License and other revenue		$ 610	$ 669	$ 1,860
Total revenues		610	669	1,860
Operating expenses:
Research and development	$ 6,763	5,251	17,866	18,066
General and administrative	3,175	3,889	10,788	12,181
Total operating expenses	9,938	9,140	28,654	30,247
Loss from operations	(9,938)	(8,530)	(27,985)	(28,387)
Interest expense	(288)	(473)	(1,116)	(1,247)
Other income, net	67	49	266	148
Net loss	(10,159)	(8,954)	(28,835)	(29,486)
Unrealized gain (loss) on available-for-sale securities	8	(6)	21	6
Comprehensive loss	(10,151)	(8,960)	(28,814)	(29,480)
Basic and diluted loss per common share:
Net loss	$ (10,159)	$ (8,954)	$ (28,835)	$ (29,486)
Shares used in computing net loss per common share	23,678	14,503	22,106	14,480
Net loss per common share	$ (0.43)	$ (0.62)	$ (1.30)	$ (2.04)

CONDENSED CONSOLIDATED STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (28,835)		$ (29,486)
Adjustments to reconcile loss to net cash used in operating activities:
Stock-based compensation expense	2,424		3,749
Depreciation and amortization	7		8
Amortization of debt discount and debt issuance costs	217		280
Write-off debt discount upon note repayment			27
Changes in operating assets and liabilities:
Prepaids and other assets	(1,950)		(282)
Accounts payable	(330)		73
Accrued clinical expense	(669)		(319)
Accrued compensation	(419)		(119)
Other accrued liabilities	(621)		(1,091)
Deferred revenue	(610)		(1,830)
Net cash used in operating activities	(30,786)		(28,990)
Cash flows from investing activities
Purchases of property and equipment	(26)
Purchases of marketable securities			(22,386)
Proceeds from maturities of marketable securities	30,047		23,019
Sale of marketable securities			490
Net cash provided by investing activities	30,021		1,123
Cash flows from financing activities
Proceeds from notes payable			15,000
Principal payments on notes payable and final payment	(7,615)		(7,983)
Payment of financing fees and debt issuance costs			(266)
Proceeds from issuance of common stock through controlled equity offering facilities, net	8,138		21
Proceeds from exercise of warrants, stock options and stock purchase rights	133		34
Net cash provided by financing activities	656		6,806
Net decrease in cash and cash equivalents	(109)		(21,061)
Cash and cash equivalents at beginning of period	8,056	[1]	26,886
Cash and cash equivalents at end of period	7,947		5,825
Supplemental disclosure of non-cash activities
Conversion of preferred stock to common stock	$ (2,268)
Fair value of warrants issued in connection with notes payable			$ 536
[1]	The condensed consolidated balance sheet as of December 31, 2016, has been derived from the audited financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

Company Overview

Company Overview	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview	1. Company Overview Description of Business Sunesis Pharmaceutical, Inc. (“Sunesis” or the “Company”) 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 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. In January 2017, the Company announced that its Investigational New Drug (“IND”) application with the U.S. Food and Drug Administration (“FDA”) for SNS-062 had become effective. In July 2017, the Company announced the dosing of the first patient in a Phase 1B/2 study to assess the candidate's safety and activity of SNS-062 in patients with advanced B-cell malignancies after two or more prior therapies, including ibrutinib or another covalent BTK inhibitor, and including patients with BTD C481 mutations. In relation to the dosing of the first patient, the Company also made a milestone payment of $2.5 million to Biogen under the licensing agreement. The Company expects to report interim data from the Phase 1B/2 study in the second quarter of 2018. The second agreement, with Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”) is for global commercial rights to several potential first-in class, pre-clinical inhibitors of the novel target PDK1. The Company is currently evaluating SNS-510, a PDK1 inhibitor, in pre-clinical absorption, distribution, metabolism and excretion, and toxicology studies, and the Company expects to complete such evaluation with the goal of declaring a development candidate before the end of 2017. 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/2 study in combination with various anti-cancer agents in adult patients with advanced non-hematologic malignancies. 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 Acute Myeloid Leukemia (“AML”), or the VALOR trial. The VALOR trial did not meet its primary endpoint of demonstrating a statistically significant improvement in overall survival. However, based upon the results of other 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 vosaroxin plus cytarabine for the treatment of relapsed or refractory AML. In April 2017, the Company presented to the Scientific Advisory Group – Oncology (“SAG-O”) and also to the Committee for Medicinal Products for Human Use (“CHMP”). As a result of these interactions, feedback from its CHMP rapporteurs and its retained regulatory consultants and an internal assessment, the Company announced on May 1, 2017 its intention to withdraw its MAA. In July 2015, management met with the U.S. FDA, to discuss a potential regulatory filing for vosaroxin in the U.S. Based upon the meeting, the FDA recommended that the Company provide additional clinical evidence prior to any regulatory filing in the U.S. As a result of both U.S. and European regulatory interactions, Sunesis is evaluating business development approaches to fund another pivotal trial to support future marketing approvals of vosaroxin in the U.S and Europe. It is the Company’s intention to continue to support investigator-sponsored group trials with vosaroxin and to resume Company-sponsored studies if a development partner can be secured. Significant Risks and Uncertainties The Company has incurred significant losses in each year since our inception. As of September 30, 2017, we had cash, cash equivalents and marketable securities of $12.5 million and an accumulated deficit of $626.2 million. The Company expects to continue to incur significant losses for the foreseeable future as we continue the development of our kinase inhibitor pipeline, including our BTK inhibitor SNS-062. Following our decision to withdraw the European MAA for vosaroxin as a treatment for relapsed/refractory AML in patients aged 60 years or older we have prioritized our development funding on our kinase inhibitors with a focus on SNS-062. The Company has a limited number of products that are still in the early stages of approval and will require significant additional investment. The Company forecasts that, after giving consideration to funds raised in October 2017 from the sale of its common stock, preferred stock and warrants, its cash, cash equivalents and marketable securities are sufficient to enable the Company’s to meet its obligations as they come due into early 2019. The Company will require additional financing to fund working capital, repay debt and pay its obligations as they come due. Additional financing might include one or more offerings and one or more of a combination of equity securities, debt arrangements or partnership or licensing collaborations. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company. Failure to raise significant additional capital in the future would force the Company to delay or reduce the scope of the Company’s vosaroxin, SNS-062, and other development programs, potentially including any additional clinical trials or subsequent regulatory filings in Europe or the United States, and/or limit or cease the Company’s operations. The consolidated financial statements do not include any adjustments to reflect the possible future effects from the outcome of these uncertainties. 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	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The financial statements include all adjustments (consisting only of normal recurring adjustments) that management believes are necessary for a fair presentation of the periods presented. The balance sheet as of December 31, 2016 was derived from the audited financial statements as of that date. These interim financial results are not necessarily indicative of results to be expected for the full year or any other period. These unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. 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), that will supersede most existing revenue recognition guidance under GAAP. The new revenue standard requires an entity to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. Entities can choose either the retrospective or cumulative effect transition method. The new revenue standard as amended by ASU No. 2015-14, is effective for annual and interim periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing, and ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients. These pronouncements have the same effective date as the new revenue standard and provide additional guidance, clarification and practical expedients to reduce the cost and complexity of applying the new standard. The guidance allows for adoption on either a full retrospective or a modified retrospective basis. The Company has identified the existing contracts likely to fall under ASC 606 and plans to adopt this guidance on January 1, 2018 applying the modified-retrospective approach. The Company has identified the agreements that will be impacted by the adoption of ASC 606. 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 June 2016, the FASB issued ASU No. 2016-13, 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 standard will be effective for annual periods beginning after December 15, 2019, with early adoption permitted beginning in 2019. Entities will apply the guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The Company will evaluate the guidance and present the impact in its consolidated financial statements at the time of adoption. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting 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, debt instruments, revenue recognition, stock-based compensation and clinical trial accounting. Cash Equivalents and Marketable Securities 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 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 September 30, 2017 and December 31, 2016, the Company held cash and investments denominated in Euros with an aggregate fair value of $0.8 million and $0.7 million, respectively. Any cash, cash equivalent and marketable securities balances denominated in foreign currencies are recorded at their fair value based on the current exchange rate as of each balance sheet date. The resulting exchange gains or losses and those from amounts payable for services originally denominated in foreign currencies are recorded in other income, net in the statements of operations and comprehensive loss. Fair Value Measurements The Company measures cash equivalents and marketable securities at fair value on a recurring basis and warrants issued in connection with debt on a non-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 carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, deferred revenue and notes payable approximated their fair value as of September 30, 2017 and December 31, 2016.

Loss per Common Share

Loss per Common Share	9 Months Ended
	Sep. 30, 2017
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 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 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): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Warrants to purchase shares of common stock 218 269 218 269 Convertible preferred stock 3,831 3,367 3,831 3,367 Options to purchase shares of common stock 2,458 2,022 2,458 2,022 Restricted stock units — 57 — 57 Outstanding securities not included in calculations 6,507 5,715 6,507 5,715

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2017
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): September 30, 2017 Input Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds Level 1 $ 5,474 $ — $ — $ 5,474 U.S. Treasury securities Level 1 3,010 — (1 ) 3,009 U.S. certificates of deposit Level 1 493 — — 493 U.S. corporate debt obligations Level 2 1,004 — — 1,004 Total available-for-sale securities 9,981 — (1 ) 9,980 Less amounts classified as cash equivalents (5,474 ) — — (5,474 ) Amounts classified as marketable securities $ 4,507 $ — $ (1 ) $ 4,506 December 31, 2016 Input Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair 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 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 The following table summarizes the available-for-sale securities that were in an unrealized loss position as of the date indicated, having been in such position for less than 12 months, and none having been deemed to be other-than temporarily impaired (in thousands): September 30, 2017 Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities $ (1 ) $ 3,009 $ (1 ) $ 3,009 December 31, 2016 Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities $ (9 ) $ 16,020 U.S. corporate debt obligations (11 ) 11,606 U.S. commercial paper (2 ) 2,519 $ (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. As of September 30, 2017, we did not hold any investments with a maturity exceeding 12 months or that have been in a continuous loss position for 12 months or more. We do not intend to sell the securities that are in an unrealized loss position and it is more likely than not that the investments will be held until recovery of the amortized cost bases. We have determined that the gross unrealized losses on our securities as of September 30, 2017 were temporary in nature. There were no realized gains or losses on the available-for-sale securities during nine months ended September 30, 2017 or 2016.

Royalty Agreement

Royalty Agreement	9 Months Ended
	Sep. 30, 2017
Revenue Recognition [Abstract]
Royalty Agreement	5. 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 fully amortized to revenue over the related performance period. 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	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	6. License Agreements Biogen In December 2013, the Company entered into a second amended and restated collaboration agreement with Biogen Idec MA, Inc. (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 first amended and restated collaboration agreement with Biogen (the “Biogen 1st ARCA”), solely for oncology indications. During the third quarter of 2017, the Company made a milestone payment of $2.5 million to Biogen upon the dosing of the first patient in a Phase 1B/2 study to assess the safety and activity of SNS-062 in patients with advanced B-cell malignancies after two or more prior therapies, including ibrutinib or other covalent BTK inhibitor, and including patients with BTD C481 mutations. The payment was recorded in the research and development expenses line item in the accompanying consolidated statement of operations. The Company may also be required to make royalty payments on 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 In March 2011, Takeda Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”) purchased and exclusively licensed Biogen’s rights to a PDK1 inhibitor program and a pan-Raf inhibitor program which were both originally developed through a collaboration agreement between Sunesis and Biogen. 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 execution of the Amended Takeda Agreement, the Company paid an upfront fee and may be required to make up to $9.2 million in pre-commercialization milestone payments depending on its development of PDK1 inhibitors and royalty payments depending on related product sales, if any. With respect to the pan-Raf inhibitor program, 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. Under this program, Takeda is currently conducting Phase 1B/2 clinical studies of an oral investigative drug, TAK-580 (formerly MLN2480).

Notes Payable

Notes Payable	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Notes Payable	7. Notes Payable On March 31, 2016, the Company entered into a loan and security agreement (the “Loan Agreement”) with Western Alliance Bank (“Western Bank”) and Solar Capital Ltd. (“Solar Capital,” and collectively with Western Bank, the “Lenders”) and Western Alliance, as Collateral Agent (the “Collateral Agent”). Pursuant to the terms of the Loan Agreement, the Lenders provided the Company with a loan in the principal amount of $15,000,000, for working capital, to fund its general business requirements and to repay indebtedness of the Company to Oxford Finance LLC, Silicon Valley Bank and Horizon Technology Finance Corporation (collectively, the “Existing Lenders”) pursuant to the Loan and Security Agreement, dated as of October 18, 2011, entered into by and among the Existing Lenders and the Company (the “Oxford Loan Agreement”). On March 31, 2016, the Company used $7.2 million of the loan proceeds to repay the outstanding principal of $6.0 million, a final payment fee of $1.2 million and accrued interest of $45,000 under the Oxford Loan Agreement. The Company paid the Lenders a $0.1 million facility fee and $0.1 million in legal fees. On June 30, 2017, the Company entered into an amendment to the existing Loan Agreement (the “Amended Loan Agreement”). Under terms of the Amended Loan Agreement, 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. The Amendment modified the loan repayment terms to be interest-only through July 1, 2018, followed by twenty-two (22) equal monthly payments of principal and interest through the maturity date, contingent upon receipt of at least Fifteen Million Dollars ($15,000,000) in unrestricted cash proceeds received after June 1, 2017 from the issuance by the Company of new equity securities any time after June 1, 2017, but on or prior to December 31, 2017. 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 28 months, unless the interest only period is extended by a further six months, in which case the amortization period will be 22 months. In addition to principal and interest, a final payment equal to $312,500 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 1.0 % of the amount prepaid if the prepayment occurs after June 30, 2017 but on or prior to March 31, 2018 and 0.5 % of the amount prepaid if the prepayment occurs thereafter. In conjunction with the Loan Agreement, the Lenders were issued five-year warrants to purchase an aggregate of up to 208,002 shares of the Company’s common stock at a per share exercise price of $3.2454. The fair value of the warrants issued was estimated to be $0.5 million using a Black-Scholes valuation model with the following assumptions: common stock price at issuance of $3.24; exercise price of $3.2454; risk-free interest rate of 1.21% based upon observed risk-free interest rates; expected volatility of 111.96% based on the Company’s average historical volatility; expected term of five years, which is the contractual life of the warrants; and a dividend yield of 0%. The fair value was 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 Agreement, using the effective interest method . Pursuant to the Loan Agreement and the Amendment Amended Loan Agreement Amended Loan Agreement Amended Loan Agreement Amended Loan Agreement Amended Loan Agreement Amended Loan Agreement The Amended Loan Agreement defines certain events of default, including instances of a Material Adverse Change in our operations, which may require prepayment of the outstanding loan. No such events have occurred or are anticipated as of September 30, 2017. 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 Amended Loan Agreement Aggregate future minimum payments due under the Loan Agreement as of September 30, 2017 were as follows (in thousands): Year ending December 31, Total 2017 $ 122 2018 3,664 2019 3,618 2020 1,447 Total minimum payments 8,851 Less amount representing interest (1,351 ) Total notes payable as of September 30, 2017 7,500 Less unamortized debt discount and issuance costs (348 ) Less current portion of notes payable (2,500 ) Non-current portion of notes payable $ 4,652

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Controlled Equity Offerings In August 2011, the Company entered into a Controlled Equity Offering SM During the nine months ended September 30, 2017, 2,571,521 shares of common stock were sold under the Sales Agreement for net proceeds of $8.1 million. As of September 30, 2017, $9.4 million of common stock remained available to be sold under this facility, subject to certain conditions as specified in the Sales Agreement, as amended.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation 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. Forfeitures are recognized as they occur. The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Research and development $ 17 $ 380 $ 670 $ 1,281 General and administrative 467 693 1,701 2,296 Employee stock-based compensation expense 484 1,073 2,371 3,577 Non-employee stock-based compensation expense 17 18 53 172 Total stock-based compensation expense $ 501 $ 1,091 $ 2,424 $ 3,749 On June 9, 2017, the Company filed a Tender Offer Statement on Schedule TO relating to an option exchange program for its officers and employees (the “Option Exchange”) to exchange certain stock options to purchase up to an aggregate of 781,505 shares of its common stock that had been granted to eligible holders, for a lesser number of new stock options with a lower exercise price. Stock options with an exercise price greater than or equal to $8.00 , and held by eligible holders in continuous service through the termination of the Option Exchange, were eligible for exchange in the program. An exchange ratio of 1.30 for 1 was applied to options priced from $8.00 to $19.99, and an exchange ratio of 1.75 for 1 was applied to options priced at $20.00 or greater. As of the closing of the Option Exchange on July 10, 2017, 25 eligible holders had tendered an aggregate of 778,928 options for 543,650 new options to purchase shares of the Company’s common stock. Each new stock option was granted on July 10, 2017, pursuant to the Company’s 2011 Equity Incentive Plan with an exercise price per share of $2.62 per share, which was the closing market price on the grant date of the new options. The exchange of stock options was treated as a modification for accounting purposes and resulted in an incremental expense of $68,471, for the vested options, which was calculated using the Black-Scholes option pricing model. The incremental expense together with the unamortized expense remaining on the unvested options is being amortized over the vesting period of the new options.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events In October 2017, the Company sold an aggregate of 2,749,630 shares of common stock under the Sales Agreement for net proceeds of $6.0 million, after deducting Cantor’s commission. In October 2017, the Company completed underwritten public offerings of (i) 7,500,000 shares of its common stock and accompanying warrants to purchase 3,750,000 shares of its common stock at a price to the public of $2.00 for each share of common stock and warrant to purchase 0.5 shares of common stock, and (ii) 2,500 shares of its non-voting Series D Convertible Preferred Stock (“Series D Stock”) and accompanying warrants to purchase 1,250,000 shares of its common stock at a price to the public of $2,000 for each share of Series D Stock and warrant to purchase 500 shares of common stock. The exercise price of the warrants is $3.00 per whole share of common stock. The warrants may be exercised at any time until and including October 27, 2018. Gross proceeds from the sale were $20.0 million and net proceeds were approximately $18.6 million. If exercised in full, the warrants could result in additional net financing proceeds to the Company of up to $15 million. Each share of non-voting Series D Stock is convertible into 1,000 shares of the Company’s 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 the Company’s common stock then outstanding. The proceeds from the underwritten public offering also extended the loan repayment terms under the Amended Loan Agreement to be interest-only through July 1, 2017. On October 31, 2017, the Company entered into a second amendment to the Amended Loan Agreement (the “Second Amendment”). The Second amendment modified the loan repayment terms to add two additional extended interest-only periods beyond July 1, 2018. If under the terms of the Amended Loan Agreement, the interest-only period has been extended to July 1, 2018, the Company may further extend the interest-only period to October 1, 2018, contingent upon the receipt of at least Fifteen Million dollars ($15,000,000) in unrestricted net cash proceeds from the issuance by the Company of new equity securities or as a non-refundable upfront payment on a new business development agreement or royalty financing agreement (the “New Capital”), on or after October 24, 2017, but on or prior to December 31, 2017. Subsequently, the Company may further extend the interest-only period to January 1, 2019, contingent upon the receipt of at least Twenty-Five Million dollars ($25,000,000) in New Capital (inclusive of any prior amounts received after October 24, 2017), on or after October 24, 2017, but on or prior to September 15, 2018.

Summary of Significant Accoun15

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The financial statements include all adjustments (consisting only of normal recurring adjustments) that management believes are necessary for a fair presentation of the periods presented. The balance sheet as of December 31, 2016 was derived from the audited financial statements as of that date. These interim financial results are not necessarily indicative of results to be expected for the full year or any other period. These unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.
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), that will supersede most existing revenue recognition guidance under GAAP. The new revenue standard requires an entity to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. Entities can choose either the retrospective or cumulative effect transition method. The new revenue standard as amended by ASU No. 2015-14, is effective for annual and interim periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net), ASU 2016-10, Revenue from Contracts with Customers: Identifying Performance Obligations and Licensing, and ASU 2016-12, Revenue from Contracts with Customers: Narrow-Scope Improvements and Practical Expedients. These pronouncements have the same effective date as the new revenue standard and provide additional guidance, clarification and practical expedients to reduce the cost and complexity of applying the new standard. The guidance allows for adoption on either a full retrospective or a modified retrospective basis. The Company has identified the existing contracts likely to fall under ASC 606 and plans to adopt this guidance on January 1, 2018 applying the modified-retrospective approach. The Company has identified the agreements that will be impacted by the adoption of ASC 606. 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 June 2016, the FASB issued ASU No. 2016-13, 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 standard will be effective for annual periods beginning after December 15, 2019, with early adoption permitted beginning in 2019. Entities will apply the guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The Company will evaluate the guidance and present the impact in its consolidated financial statements at the time of adoption. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting
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, debt instruments, revenue recognition, stock-based compensation and clinical trial accounting.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities 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 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 September 30, 2017 and December 31, 2016, the Company held cash and investments denominated in Euros with an aggregate fair value of $0.8 million and $0.7 million, respectively. Any cash, cash equivalent and marketable securities balances denominated in foreign currencies are recorded at their fair value based on the current exchange rate as of each balance sheet date. The resulting exchange gains or losses and those from amounts payable for services originally denominated in foreign currencies are recorded in other income, net in the statements of operations and comprehensive loss.
Fair Value Measurements	Fair Value Measurements The Company measures cash equivalents and marketable securities at fair value on a recurring basis and warrants issued in connection with debt on a non-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 carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, deferred revenue and notes payable approximated their fair value as of September 30, 2017 and December 31, 2016.

Loss per Common Share (Tables)

Loss per Common Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
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): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Warrants to purchase shares of common stock 218 269 218 269 Convertible preferred stock 3,831 3,367 3,831 3,367 Options to purchase shares of common stock 2,458 2,022 2,458 2,022 Restricted stock units — 57 — 57 Outstanding securities not included in calculations 6,507 5,715 6,507 5,715

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
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): September 30, 2017 Input Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds Level 1 $ 5,474 $ — $ — $ 5,474 U.S. Treasury securities Level 1 3,010 — (1 ) 3,009 U.S. certificates of deposit Level 1 493 — — 493 U.S. corporate debt obligations Level 2 1,004 — — 1,004 Total available-for-sale securities 9,981 — (1 ) 9,980 Less amounts classified as cash equivalents (5,474 ) — — (5,474 ) Amounts classified as marketable securities $ 4,507 $ — $ (1 ) $ 4,506 December 31, 2016 Input Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair 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 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
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 the date indicated, having been in such position for less than 12 months, and none having been deemed to be other-than temporarily impaired (in thousands): September 30, 2017 Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities $ (1 ) $ 3,009 $ (1 ) $ 3,009 December 31, 2016 Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities $ (9 ) $ 16,020 U.S. corporate debt obligations (11 ) 11,606 U.S. commercial paper (2 ) 2,519 $ (22 ) $ 30,145

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Agreement	Aggregate future minimum payments due under the Loan Agreement as of September 30, 2017 were as follows (in thousands): Year ending December 31, Total 2017 $ 122 2018 3,664 2019 3,618 2020 1,447 Total minimum payments 8,851 Less amount representing interest (1,351 ) Total notes payable as of September 30, 2017 7,500 Less unamortized debt discount and issuance costs (348 ) Less current portion of notes payable (2,500 ) Non-current portion of notes payable $ 4,652

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
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): Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Research and development $ 17 $ 380 $ 670 $ 1,281 General and administrative 467 693 1,701 2,296 Employee stock-based compensation expense 484 1,073 2,371 3,577 Non-employee stock-based compensation expense 17 18 53 172 Total stock-based compensation expense $ 501 $ 1,091 $ 2,424 $ 3,749

Company Overview - Additional I

Company Overview - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016	[1]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Cash, cash equivalents and marketable securities	$ 12,500	$ 12,500
Accumulated deficit	626,231	$ 626,231	$ 597,396
Maturity limits period		24 months
Dollars weighted average maturity limit period		12 months
Biogen [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Milestone payment	$ 2,500
[1]	The condensed consolidated balance sheet as of December 31, 2016, has been derived from the audited financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

Summary of Significant Accoun21

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)Segment	Dec. 31, 2016USD ($)
Accounting Policies [Abstract]
Number of reportable segment | Segment	1
Fair value of investments denominated in Euros | $	$ 0.8	$ 0.7

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	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	6,507	5,715	6,507	5,715
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	269	218	269
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	2,458	2,022	2,458	2,022
Restricted stock units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations		57		57
Convertible preferred stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	3,831	3,367	3,831	3,367

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	$ 9,981	$ 38,305
Available-for-sale securities, Gross Unrealized Losses	(1)	(22)
Available-for-sale securities, Estimated Fair Value	9,980	38,283
Less amounts classified as cash equivalents, Amortized Cost	(5,474)	(3,751)
Less amounts classified as cash equivalents, Estimated Fair Value	(5,474)	(3,751)
Amounts classified as marketable securities, Amortized Cost	4,507	34,554
Amounts classified as marketable securities, Gross Unrealized Losses	(1)	(22)
Amounts classified as marketable securities, Estimated Fair Value	4,506	34,532	[1]
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	5,474	3,270
Available-for-sale securities, Estimated Fair Value	5,474	3,270
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	3,010	16,029
Available-for-sale securities, Gross Unrealized Losses	(1)	(9)
Available-for-sale securities, Estimated Fair Value	3,009	16,020
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	493	4,868
Available-for-sale securities, Estimated Fair Value	493	4,868
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	1,004	11,617
Available-for-sale securities, Gross Unrealized Losses		(11)
Available-for-sale securities, Estimated Fair Value	$ 1,004	11,606
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
[1]	The condensed consolidated balance sheet as of December 31, 2016, has been derived from the audited financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

Financial Instruments - Summary

Financial Instruments - Summary of Available-for-Sale Securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	$ (1)	$ (22)
Estimated Fair Value	3,009	30,145
U.S. commercial paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses		(2)
Estimated Fair Value		2,519
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Gross Unrealized Losses	(1)	(9)
Estimated Fair Value	$ 3,009	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

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Realized gains or losses on available-for-sale securities	$ 0	$ 0

Royalty Agreement - Additional

Royalty Agreement - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2012
Royalty Agreement [Line Items]
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
Fair value of warrants issued in connection with participation agreement	$ 3.1

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2017	Jan. 31, 2014
License Agreement Terms [Member] | Takeda License Agreements [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization milestone payments payable		$ 9.2
Potential pre-commercialization payments receivable	$ 57.5
Biogen [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment	$ 2.5

Notes Payable - Additional Info

Notes Payable - Additional Information (Detail) - USD ($)	Jun. 30, 2017	Mar. 31, 2016	Sep. 30, 2017
Loan Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 15,000,000
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
Line of credit facility final payment, additional amount due	$ 312,500
Percentage of penalty for prepaying loan after maturity	0.50%
Prepayment penalty expiration date			Jun. 30, 2017
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 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%
Amended Loan Agreement [Member]
Debt Instrument [Line Items]
Description of monthly interest payment			The Amendment modified the loan repayment terms to be interest-only through July 1, 2018, followed by twenty-two (22) equal monthly payments of principal and interest through the maturity date, contingent upon receipt of at least Fifteen Million Dollars ($15,000,000) in unrestricted cash proceeds received after June 1, 2017 from the issuance by the Company of new equity securities any time after June 1, 2017, but on or prior to December 31, 2017. 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 28 months, unless the interest only period is extended by a further six months, in which case the amortization period will be 22 months.
Debt instrument, minimum threshold amount of unrestricted cash proceeds from issuance of new equity for principal and interest only payment period	$ 15,000,000
Loan, Covenant description			Pursuant to the Loan Agreement and the Amendment, 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 Amended 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 Amended 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 Amended 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 Amended 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 Amended Loan Agreement; and the failure of any representation or warranty made by the Company in connection with the Amended Loan Agreement to be correct in all material respects when made. The Amended Loan Agreement defines certain events of default, including instances of a Material Adverse Change in our operations, which may require prepayment of the outstanding loan. No such events have occurred or are anticipated as of September 30, 2017.

Notes Payable - Summary of Futu

Notes Payable - Summary of Future Minimum Payments Under Loan Agreement (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	[1]
Debt Instrument [Line Items]
Total notes payable as of September 30, 2017	$ 7,500
Less current portion of notes payable	(2,500)	$ (3,333)
Non-current portion of notes payable	4,652	$ 11,102
Notes payable [Member]
Debt Instrument [Line Items]
2,017	122
2,018	3,664
2,019	3,618
2,020	1,447
Total minimum payments	8,851
Less amount representing interest	(1,351)
Less unamortized debt discount and issuance costs	$ (348)
[1]	The condensed consolidated balance sheet as of December 31, 2016, has been derived from the audited financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended		9 Months Ended
	Mar. 31, 2015	Apr. 30, 2013	Sep. 30, 2017	Aug. 31, 2011
Controlled Equity Offering Facilities [Member]
Stockholders Equity [Line Items]
Issuance of common stock, offering value				$ 20
Common stock sales agreement, date			2011-08
Issuance of common stock, remaining offering value			$ 9.4
Proceeds from issuance of common stock through controlled equity offering facilities, net			$ 8.1
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Common stock, shares sold			2,571,521
Additional Controlled Equity Offerings Facilities [Member]
Stockholders Equity [Line Items]
Increase in aggregate controlled equity offering agreement as per amendment	$ 30	$ 30
Issuance of common stock, commission percentage, maximum	3.00%	3.00%
Common stock sales agreement amended, date			2013-04
Common stock sales agreement further amended, date			2015-03

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 501	$ 1,091	$ 2,424	$ 3,749
Employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	484	1,073	2,371	3,577
Non-employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	17	18	53	172
Research and development [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	17	380	670	1,281
General and administrative [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 467	$ 693	$ 1,701	$ 2,296

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Jul. 10, 2017	Jun. 09, 2017	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Tender offer announcement date			Jun. 9, 2017
Options to purchase shares of common stock	778,928	781,505
New options granted to purchase shares of common stock	543,650
Exercise price of options	$ 2.62
Incremental expense for vested options			$ 68,471
Options Priced from $8.00-$19.99 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exchange ratio applied to options priced		130.00%
Exercise price of applied option price, minimum		$ 8
Exercise price of applied option price, maximum		$ 19.99
Options Priced for $20.00 or Greater [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exchange ratio applied to options priced		175.00%
Exercise price of applied option price, minimum		$ 20

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	1 Months Ended	9 Months Ended
	Oct. 31, 2017	Sep. 30, 2017
Controlled Equity Offering Facilities [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common stock through controlled equity offering facilities, net		$ 8,100,000
Common Stock [Member] | Controlled Equity Offering Facilities [Member]
Subsequent Event [Line Items]
Common stock, shares sold		2,571,521
Subsequent Event [Member] | Second Amendment [Member]
Subsequent Event [Line Items]
Description of monthly interest payment	The Second amendment modified the loan repayment terms to add two additional extended interest-only periods beyond July 1, 2018. If under the terms of the Amended Loan Agreement, the interest-only period has been extended to July 1, 2018, the Company may further extend the interest-only period to October 1, 2018, contingent upon the receipt of at least Fifteen Million dollars ($15,000,000) in unrestricted net cash proceeds from the issuance by the Company of new equity securities or as a non-refundable upfront payment on a new business development agreement or royalty financing agreement (the “New Capital”), on or after October 24, 2017, but on or prior to December 31, 2017. Subsequently, the Company may further extend the interest-only period to January 1, 2019, contingent upon the receipt of at least Twenty-Five Million dollars ($25,000,000) in New Capital (inclusive of any prior amounts received after October 24, 2017), on or after October 24, 2017, but on or prior to September 15, 2018.
Subsequent Event [Member] | Second Amendment Period One [Member]
Subsequent Event [Line Items]
Debt instrument, minimum threshold amount of unrestricted cash proceeds from issuance of new equity for principal and interest only payment period	$ 25,000,000
Subsequent Event [Member] | Second Amendment Period Two [Member]
Subsequent Event [Line Items]
Debt instrument, minimum threshold amount of unrestricted cash proceeds from issuance of new equity for principal and interest only payment period	15,000,000
Subsequent Event [Member] | Controlled Equity Offering Facilities [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common stock through controlled equity offering facilities, net	6,000,000
Subsequent Event [Member] | Underwritten Public Offerings [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common stock through controlled equity offering facilities, net	$ 18,600,000
Shares of common stock issued	7,500,000
Warrants, exercise price per share	$ 3
Warrant exercisable date description	The warrants may be exercised at any time until and including October 27, 2018
Proceeds from issuance of common shares, gross	$ 20,000,000
Subsequent Event [Member] | Underwritten Public Offerings [Member] | Maximum [Member]
Subsequent Event [Line Items]
Additional net financing proceeds upon exercisable of warrants	$ 15,000,000
Subsequent Event [Member] | Underwritten Public Offerings [Member] | Series D Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred stock, shares issued	2,500
Shares issued upon conversion	1,000
Subsequent Event [Member] | Underwritten Public Offerings [Member] | Series D Convertible Preferred Stock [Member] | Maximum [Member]
Subsequent Event [Line Items]
Percentage of Common Stock Outstanding	9.98%
Subsequent Event [Member] | Underwritten Public Offerings [Member] | Common Stock Warrants [Member]
Subsequent Event [Line Items]
Total warrants outstanding, shares	3,750,000
Price per common share	$ 2
Number of shares called by each warrant	0.5
Subsequent Event [Member] | Underwritten Public Offerings [Member] | Preferred Stock Warrants [Member]
Subsequent Event [Line Items]
Total warrants outstanding, shares	1,250,000
Price per common share	$ 2,000
Number of shares called by each warrant	500
Subsequent Event [Member] | Common Stock [Member] | Controlled Equity Offering Facilities [Member]
Subsequent Event [Line Items]
Common stock, shares sold	2,749,630