Viracta Therapeutics (VIRX) 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 01, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	SNSS
Entity Registrant Name	SUNESIS PHARMACEUTICALS INC
Entity Central Index Key	0001061027
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		72,528,000

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	[1]
Current assets:
Cash and cash equivalents	$ 24,811	$ 13,696
Prepaids and other current assets	1,599	1,504
Total current assets	26,410	15,200
Property and equipment, net	9	11
Operating lease right-of-use asset	1,226
Other assets	109	113
Total assets	27,754	15,324
Current liabilities:
Accounts payable	861	1,393
Accrued clinical expense	420	500
Accrued compensation	677	943
Other accrued liabilities	1,440	1,091
Notes payable	6,032	7,396
Operating lease liability - current	545
Total current liabilities	9,975	11,323
Other liabilities	12	8
Operating lease liability - long term	681
Total liabilities	10,668	11,331
Commitments and contingencies
Stockholders’ equity:
Convertible preferred stock	25,647	20,998
Common stock	7	4
Additional paid-in capital	656,761	642,460
Accumulated deficit	(665,329)	(659,469)
Total stockholders’ equity	17,086	3,993
Total liabilities and stockholders’ equity	$ 27,754	$ 15,324
[1]	The condensed consolidated balance sheet as of December 31, 2018, 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, 2018.

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue:
License and other revenue		$ 237
Type of Revenue [Extensible List]	snss:LicenseAndOtherRevenueMember	snss:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 3,248	$ 3,969
General and administrative	2,439	3,359
Total operating expenses	5,687	7,328
Loss from operations	(5,687)	(7,091)
Interest expense	(261)	(281)
Other income, net	88	99
Net loss	(5,860)	(7,273)
Unrealized gain on available-for-sale securities		2
Comprehensive loss	(5,860)	(7,271)
Basic and diluted loss per common share:
Net loss	$ (5,860)	$ (7,273)
Shares used in computing net loss per common share	59,142	34,345
Net loss per common share	$ (0.10)	$ (0.21)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018
Cash flows from operating activities
Net loss	$ (5,860)		$ (7,273)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	417		896
Depreciation and amortization	2		2
Amortization of debt discount and debt issuance costs	42		48
Changes in operating assets and liabilities:
Prepaids and other assets	(91)		988
Accounts payable	(532)		(659)
Accrued clinical expense	(80)		(197)
Accrued compensation	(266)		(578)
Other accrued liabilities	255		223
Net cash used in operating activities	(6,113)		(6,550)
Cash flows from investing activities
Proceeds from maturities of marketable securities			742
Net cash provided by investing activities			742
Cash flows from financing activities
Principal payments on notes payable	(1,406)
Proceeds from issuance of convertible preferred stock offering, net	7,944
Proceeds from issuance of common stock, net	10,690
Proceeds from issuance of common stock through controlled equity offering facilities, net			32
Proceeds from exercise of stock options and stock purchase rights			164
Net cash provided by financing activities	17,228		196
Net increase (decrease) in cash and cash equivalents	11,115		(5,612)
Cash and cash equivalents at beginning of period	13,696	[1]	26,977
Cash and cash equivalents at end of period	24,811		$ 21,365
Supplemental disclosure of non-cash activities
Conversion of preferred stock to common stock	3,228
Legal expenses accrued as cost of equity financing	$ 98
[1]	The condensed consolidated balance sheet as of December 31, 2018, 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, 2018.

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total		Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balances at Dec. 31, 2017	$ 21,544		$ 20,966	$ 3	$ 633,436	$ (7)	$ (632,854)
Issuance of common stock through controlled equity offering facilities, net of issuance cost					32
Issuance of common stock pursuant to stock option exercises					164
Issuance of common stock from vesting of restricted stock awards, net of shares withheld for taxes					83
Stock-based compensation expenses					813
Unrealized gain on available-for-sale securities	2					2
Net loss	(7,273)						(7,273)
Ending balances at Mar. 31, 2018	15,365		20,966	3	634,528	$ (5)	(640,127)
Beginning balances at Dec. 31, 2018	3,993	[1]	20,998	4	642,460		(659,469)
Issuance of preferred stock in underwritten offering, net of issuance costs			7,877		10,656
Issuance of common stock in underwritten offering, net of issuance costs				2	3,228
Conversion of preferred stock to common stock			(3,228)	1
Issuance of common stock from vesting of restricted stock awards, net of shares withheld for taxes					54
Stock-based compensation expenses					363
Net loss	(5,860)						(5,860)
Ending balances at Mar. 31, 2019	$ 17,086		$ 25,647	$ 7	$ 656,761		$ (665,329)
[1]	The condensed consolidated balance sheet as of December 31, 2018, 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, 2018.

Company Overview

Company Overview	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview	1. Company Overview Description of Business Sunesis Pharmaceuticals, Inc. (“Sunesis” or the “Company”) is a biopharmaceutical company focused on the development of new targeted inhibitors 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. The Company’s lead program is vecabrutinib, a selective non-covalent inhibitor of Bruton’s Tyrosine Kinase (“BTK”) with activity against both wild type and C481S-mutated BTK, the most common mutation associated with resistance to ibrutinib. Vecabrutinib is being studied in a Phase 1b/2 clinical trial to assess safety and activity in patients with advanced B-cell malignancies after two or more prior therapies, including ibrutinib or another covalent BTK inhibitor where approved for the disease. The Phase 1b portion of the study is a dose escalation component that will proceed to define a maximum tolerated dose and/or a recommended Phase 2 dose. Upon identifying the Phase 2 dose, the Phase 2 portion will further explore clinical activity and safety in disease- and mutation-specific cohorts, including patients with and without BTK C481 mutations. The Company is also developing SNS-510, a PDK1 inhibitor licensed from Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”). The Company acquired from Takeda global commercial rights to several potential first-in class, preclinical inhibitors of the novel target PDK1, including SNS-510. The Company is currently characterizing SNS-510 through preclinical pharmacology studies, manufacturing and formulation activities. The Company is in a collaboration with Takeda for the development of TAK-580 (formerly MLN2480), an oral pan-RAF inhibitor, which is under investigation for pediatric low-grade glioma. Liquidity and Going Concern The Company has incurred significant losses and negative cash flows from operations since its inception, and as of March 31, 2019, the Company had cash and cash equivalents totaling $24.8 million and an accumulated deficit of $665.3 million. The Company expects to continue to incur significant losses for the foreseeable future as it continues development of its kinase inhibitor pipeline, including its BTK inhibitor, vecabrutinib. The Company has prioritized development funding on its kinase inhibitor portfolio with a focus on vecabrutinib. The Company has a limited number of products that are still in the early stages of development and will require significant additional future investment. The Company’s cash and cash equivalents are not sufficient to support its operations for a period of twelve months from the date these condensed consolidated financial statements are available to be issued. These factors raise substantial doubt about its ability to continue as a going concern. 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. If the Company is unsuccessful in its efforts to raise additional financing in the near term, the Company will be required to significantly reduce or cease operations. The principal payments due under the Loan Agreement (as defined in Note 6) have been classified as a current liability as of March 31, 2019 and December 31, 2018 due to the considerations discussed above and the assessment that the material adverse change clause under the Loan Agreement is not within the Company's control. In April 2019, the Company used the proceeds of the SVB Loan Agreement (as defined in Note 10) plus cash on hand to repay its remaining obligations in the amount of $5.9 million under Loan Agreement and Amendments (as defined in Note 6). The SVB Loan Agreement also contains customary events of default, including among other things, the Company’s failure to make any principal or interest payments when due, the occurrence of certain bankruptcy or insolvency events or its breach of the covenants under the SVB Loan Agreement. Upon the occurrence of an event of default, SVB (as defined in Note 10) may, among other things, accelerate the Company’s obligations under the SVB Loan Agreement. The Company has not been notified of an event of default by SVB as of the date of the filing of this Form 10-Q. The accompanying condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The condensed consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern . Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash and cash equivalents. 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 condensed consolidated balance sheets.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
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 condensed consolidated 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, 2018 was derived from the audited consolidated 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, 2018. Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements Leases (Topic 842): Codification Improvements The Company has elected the package of practical expedients permitted under ASC 842. Accordingly, the Company accounted for its existing operating leases as operating leases under the new guidance, without reassessing (a) whether the contracts contain a lease under ASC Topic 842, (b) whether classification of the operating leases would be different in accordance with ASC Topic 842, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs in ASC Topic 842 at lease commencement. In addition, the Company made an accounting policy election to combine the lease and non-lease components and the short-term lease practical expedients allowed under ASC 842. As a result of the adoption of ASC 842, the Company recognized on January 1, 2019 (a) a lease liability of approximately $1,362,000, which represents the present value of the remaining lease payments of approximately $1,434,000, discounted using the Company’s incremental borrowing rate of 4.0%, and (b) a right-of-use (“ROU”) asset equal to the lease liability of approximately $1,362,000. Once recorded, the Company also evaluates the right-of-use asset for impairment as part of an asset group, following the principles of ASC 360, Property, Plant, and Equipment The adoption of the new standard resulted in changes to the Company’s accounting policies for leases as detailed below. In June 2018, the FASB issued ASU No. 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement . Leases The Company determines if an arrangement is or contains a lease at inception. In determining whether an arrangement is a lease, the Company considers whether (1) explicitly or implicitly identified assets have been deployed in the arrangement and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term. When an implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for new leases or effective date for existing leases, in determining the present value of lease payments. Leases may contain initial periods of free rent and/or periodic escalations. When such items are included in a lease agreement, the Company records rent expense on a straight-line basis over the initial term of a lease. The difference between the rent payment and the straight-line rent expense is recorded as a deferred rent liability. The Company expenses any additional payments under its operating leases for taxes, insurance or other operating expenses as incurred . Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sunesis Europe Limited, a United Kingdom corporation. All intercompany balances and transactions have been eliminated in consolidation. 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 condensed 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, ROU assets, lease liabilities, and clinical trial accounting. Fair Value Measurements The Company measures cash equivalents 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 carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, and notes payable approximated their fair value as of March 31, 2019 and December 31, 2018.

Loss per Common Share

Loss per Common Share	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 2018 Warrants to purchase shares of common stock 218 5,218 Convertible preferred stock 16,331 6,331 Options to purchase shares of common stock 4,005 3,288 Outstanding securities not included in calculations 20,554 14,837

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2019
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 are comprised solely of available-for-sale securities classified as cash equivalents (in thousands): March 31, 2019 Input Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds Level 1 $ 19,735 $ — $ — $ 19,735 Total available-for-sale securities classified as cash equivalents 19,735 - - 19,735 Less amounts classified as cash equivalents (19,735 ) — — (19,735 ) Amounts classified as marketable securities $ — $ — $ — $ — December 31, 2018 Input Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Value Money market funds Level 1 $ 10,845 $ — $ — $ 10,845 Total available-for-sale securities 10,845 — — 10,845 Less amounts classified as cash equivalents (10,845 ) — — (10,845 ) Amounts classified as marketable securities $ — $ — $ — $ — There were no available-for-sale securities in an unrealized gain or loss position as of March 31, 2019 and December 31, 2018.

License Agreements

License Agreements	3 Months Ended
	Mar. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	5. License Agreements Biogen In December 2013, the Company entered into a second amended and restated collaboration agreement with Biogen Inc. (the “Biogen 2nd ARCA”), to provide the Company with an exclusive worldwide license to develop, manufacture and commercialize vecabrutinib, a BTK inhibitor synthesized under an earlier collaboration with Biogen, solely for oncology indications. During the third quarter of 2017, the Company made the final milestone payment of $2.5 million to Biogen upon the dosing of the first patient in the Phase 1b/2 study to assess the safety and activity of vecabrutinib in patients with advanced B-cell malignancies. The payment was recorded in the research and development expenses line item in the consolidated statement of operations. The Company may also be required to make tiered royalty payments based on percentages of net sales of vecabrutinib, if any, in the mid-single-digits. Takeda In March 2011, Takeda Oncology, a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”) purchased exclusive rights to the PDK1 inhibitor and pan-Raf inhibitor programs which were both originally developed through the Company’s collaboration with 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 tiered royalty payments based on percentages of net sales, if any, beginning in the mid-single-digits and not to exceed the low-teens. With respect to the pan-Raf inhibitor program, TAK-580 (formerly MLN2480), 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. TAK-580 is currently being studied in a Phase 1b/2 clinical study for children with low-grade gliomas. As of March 31, 2019, all future event-based payments and royalty payments are considered fully constrained variable considerations and therefore, no contract assets have been recorded and no revenue have been recognized.

Notes Payable

Notes Payable	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Notes Payable	6. Notes Payable In 2017, the Company entered into two amendments (the “Amendments”) to its existing loan agreement (the “Loan Agreement”) with Western Alliance Bank and Solar Capital Ltd. (the “Lenders”) and Western Alliance, as Collateral Agent (the “Collateral Agent”). Under terms of the Amendments, 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. In addition to principal and interest, a final payment equal to $312,500 will be due upon maturity date of April 1, 2020 or such earlier date specified in the Loan Agreement and the Amendments and the Amendments 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. 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 Amendments, the Company is bound during the term of the Loan Agreement and the Amendments by a variety of affirmative covenants, including, without limitation, certain information delivery requirements and notice requirements, and negative covenants, including, without limitation, restrictions on 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 and the Amendments (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. In the event of default by the Company, the Lenders would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the Loan Agreement and the Amendments, which could harm the Company's financial condition. The Company was in compliance with all applicable covenants set forth in the Loan Agreement and the Amendments as of March 31, 2019 and December 31, 2018. . 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 and the Amendments Aggregate future minimum payments due under the Loan Agreement and the Amendments Through December 31, Total 2019 4,568 2020 2,231 Total minimum payments 6,799 Less amount representing interest (705 ) Total notes payable as of March 31, 2019 6,094 Less unamortized debt discount and issuance costs (62 ) Less carrying amount of notes payable (6,032 ) Non-current portion of notes payable $ — In April 2019, the Company entered into a term loan agreement with SVB (“SVB Loan Agreement”), pursuant to which the Company borrowed $5.5 million. The Company used the proceeds of the SVB Loan Agreement plus cash on hand to repay its remaining obligations in the amount of $5.9 million under the Loan Agreement and the Amendments (refer to Note 10 Subsequent Events for additional details).

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Underwritten Offerings In January 2019, the Company completed underwritten public offerings of (i) 23,000,000 shares of its common stock at a price to the public of $0.50 for each share of common stock, and (ii) 17,000 shares of its non-voting Series E Convertible Preferred Stock (“Series E Stock”) at a price to the public of $500 for each share of Series E Stock. Gross proceeds from the sale were $20.0 million and net proceeds were approximately $18.6 million. Each share of non-voting Series E 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; provided, however, that a holder may, upon written notice, elect to increase or decrease this percentage (not to exceed the limits under Nasdaq Marketplace Rule 5635(b), to the extent applicable). During the three months ended March 31, 2019, 7,000 shares of Series E Stock were converted into 7,000,000 shares of common stock with the remaining 10,000 shares of Series E Stock outstanding as of March 31, 2019. Controlled Equity Offerings Cantor Controlled Equity Offering During the three months ended March 31, 2019, no shares of common stock were sold under the Controlled Equity Offering SM Aspire Common Stock Purchase Agreement During the three months ended March 31, 2019, no shares were issued under the Common Stock Purchase Agreement (the “CSPA”) with Aspire Capital Fund, LLC (“Aspire”). Aspire’s remaining purchase commitment was $10.9 million as of March 31, 2019.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation Employee and non-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 March 31, 2019 2018 Research and development $ 156 $ 164 General and administrative 216 234 Employee stock-based compensation expense 372 398 Non-employee stock-based compensation expense 45 498 Total stock-based compensation expense $ 417 $ 896

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	9. Leases The Company’s operating lease obligation s solely ing The lease was entered into in January 2014 and was amended several times since 2014. The cash paid for operating lease liability was $0.1 million and the ROU asset obtained in exchange for new operating lease liability was $1.4 million, for the three months ended March 31, 2019. Maturity of lease liability is as follows (in thousands): Through December 31, 2019 $ 424 2020 578 2021 294 Total rental payments 1,296 Less imputed interest (70 ) Present value of lease liability $ 1,226 The Company recognizes rent expense on a straight-line basis. The Company recorded rent expense of $0.1

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events In April 2019, the Company issued a total of 4,950,165 shares of its common stock from the conversion of 13,639 shares of its non-voting Series B Convertible Preferred Stock, 1,558 shares of its non-voting Series C Convertible Preferred Stock, and 1,119 shares of its non-voting Series D Convertible Preferred Stock. 1,381 shares of non-voting Series D Convertible Preferred Stock and 10,000 Series E Stock remain outstanding after the conversion. No shares of non-voting Series B or Series C Convertible Preferred Stock remain outstanding after the conversion. In April 2019, the Company entered into a term loan agreement with Silicon Valley Bank (“SVB Loan Agreement”), pursuant to which the Company borrowed $5.5 million. The Company used the proceeds of the SVB Loan Agreement plus cash on hand to repay its remaining obligations in the amount of $5.9 million under its existing Loan Agreement and Amendments. The maturity date of the SVB Loan Agreement is December 1, 2022. Under the terms of the SVB Loan Agreement, the Company is required to make interest-only payments through December 31, 2020 on the borrowings at a floating rate equal to the greater of the Prime Rate minus 2.25%, as defined in the SVB Loan Agreement, or 3.25%, followed by an amortization period of 24 months of equal monthly payments of principal plus interest amounts until paid in full. In addition to and not in substitution for the regular monthly payments of principal plus accrued interest, the Company is required to make a final payment equal to 4% of the original principal amount of the borrowings (“Final Payment Fee”). Additionally, the Company may prepay all, but not less than all of the borrowings at any time upon 30 days’ prior notice to Silicon Valley Bank (“SVB”). Any such prepayment would require, in addition to payment of principal and accrued interest as well as the Final Payment Fee, a prepayment fee, in the amount of (a) $165,000 if the prepayment occurs prior to the 1st anniversary of April 26, 2019, or the Effective Date; (b) $110,000 if the prepayment occurs on or after the 1st anniversary of the Effective Date but prior to the 2nd anniversary of the Effective Date; or (c) $55,000 if the prepayment occurs on or after the 2nd anniversary of the Effective Date. The Company’s obligations under the SVB Loan Agreement are secured by a first priority security interest in cash held at an account with SVB, the Collateral Account. The Company is obligated to maintain sufficient cash in the Collateral Account at all times in an amount greater than the outstanding balance of the borrowings. The SVB Loan Agreement contains customary affirmative and negative covenants which, among other things, limit the Company’s ability to (i) incur additional indebtedness, (ii) pay dividends or make certain distributions, (iii) dispose of its assets, grant liens or encumber its assets or (iv) fundamentally alter the nature of its business. These covenants are subject to a number of exceptions and qualifications. The SVB Loan Agreement also contains customary events of default, including among other things, the Company’s failure to make any principal or interest payments when due, the occurrence of certain bankruptcy or insolvency events or its breach of the covenants under the SVB Loan Agreement. Upon the occurrence of an event of default, SVB may, among other things, accelerate the Company’s obligations under the SVB Loan Agreement .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“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 condensed consolidated 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, 2018 was derived from the audited consolidated 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, 2018.
Adopted Accounting Pronouncements	Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements Leases (Topic 842): Codification Improvements The Company has elected the package of practical expedients permitted under ASC 842. Accordingly, the Company accounted for its existing operating leases as operating leases under the new guidance, without reassessing (a) whether the contracts contain a lease under ASC Topic 842, (b) whether classification of the operating leases would be different in accordance with ASC Topic 842, or (c) whether the unamortized initial direct costs before transition adjustments would have met the definition of initial direct costs in ASC Topic 842 at lease commencement. In addition, the Company made an accounting policy election to combine the lease and non-lease components and the short-term lease practical expedients allowed under ASC 842. As a result of the adoption of ASC 842, the Company recognized on January 1, 2019 (a) a lease liability of approximately $1,362,000, which represents the present value of the remaining lease payments of approximately $1,434,000, discounted using the Company’s incremental borrowing rate of 4.0%, and (b) a right-of-use (“ROU”) asset equal to the lease liability of approximately $1,362,000. Once recorded, the Company also evaluates the right-of-use asset for impairment as part of an asset group, following the principles of ASC 360, Property, Plant, and Equipment The adoption of the new standard resulted in changes to the Company’s accounting policies for leases as detailed below. In June 2018, the FASB issued ASU No. 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement .
Leases	Leases The Company determines if an arrangement is or contains a lease at inception. In determining whether an arrangement is a lease, the Company considers whether (1) explicitly or implicitly identified assets have been deployed in the arrangement and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term. When an implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for new leases or effective date for existing leases, in determining the present value of lease payments. Leases may contain initial periods of free rent and/or periodic escalations. When such items are included in a lease agreement, the Company records rent expense on a straight-line basis over the initial term of a lease. The difference between the rent payment and the straight-line rent expense is recorded as a deferred rent liability. The Company expenses any additional payments under its operating leases for taxes, insurance or other operating expenses as incurred .
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sunesis Europe Limited, a United Kingdom corporation. All intercompany balances and transactions have been eliminated in consolidation.
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 condensed 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, ROU assets, lease liabilities, and clinical trial accounting.
Fair Value Measurements	Fair Value Measurements The Company measures cash equivalents 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 carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, and notes payable approximated their fair value as of March 31, 2019 and December 31, 2018.

Loss per Common Share (Tables)

Loss per Common Share (Tables)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 2018 Warrants to purchase shares of common stock 218 5,218 Convertible preferred stock 16,331 6,331 Options to purchase shares of common stock 4,005 3,288 Outstanding securities not included in calculations 20,554 14,837

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
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 are comprised solely of available-for-sale securities classified as cash equivalents (in thousands): March 31, 2019 Input Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds Level 1 $ 19,735 $ — $ — $ 19,735 Total available-for-sale securities classified as cash equivalents 19,735 - - 19,735 Less amounts classified as cash equivalents (19,735 ) — — (19,735 ) Amounts classified as marketable securities $ — $ — $ — $ — December 31, 2018 Input Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Value Money market funds Level 1 $ 10,845 $ — $ — $ 10,845 Total available-for-sale securities 10,845 — — 10,845 Less amounts classified as cash equivalents (10,845 ) — — (10,845 ) Amounts classified as marketable securities $ — $ — $ — $ —

Notes Payable (Tables)

Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Agreement	Aggregate future minimum payments due under the Loan Agreement and the Amendments Through December 31, Total 2019 4,568 2020 2,231 Total minimum payments 6,799 Less amount representing interest (705 ) Total notes payable as of March 31, 2019 6,094 Less unamortized debt discount and issuance costs (62 ) Less carrying amount of notes payable (6,032 ) Non-current portion of notes payable $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 2018 Research and development $ 156 $ 164 General and administrative 216 234 Employee stock-based compensation expense 372 398 Non-employee stock-based compensation expense 45 498 Total stock-based compensation expense $ 417 $ 896

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Maturity of Lease Liability	Maturity of lease liability is as follows (in thousands): Through December 31, 2019 $ 424 2020 578 2021 294 Total rental payments 1,296 Less imputed interest (70 ) Present value of lease liability $ 1,226

Company Overview - Additional I

Company Overview - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	[1]	Mar. 31, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Cash and cash equivalents		$ 24,811	$ 13,696		$ 21,365	$ 26,977
Accumulated deficit		$ 665,329	$ 659,469
Amended Loan Agreement [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Repayment of remaining obligations	$ 5,900
[1]	The condensed consolidated balance sheet as of December 31, 2018, 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, 2018.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Mar. 31, 2019	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Lease liability	$ 1,226,000
Present value of remaining lease payments	1,296,000
Right-of-use asset	$ 1,226,000
ASC 842
Significant Accounting Policies [Line Items]
Lease liability		$ 1,362,000
Present value of remaining lease payments		$ 1,434,000
Incremental borrowing rate		4.00%
Right-of-use asset		$ 1,362,000

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
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	20,554	14,837
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	5,218
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	4,005	3,288
Convertible preferred stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	16,331	6,331

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	$ 19,735	$ 10,845
Available-for-sale securities, Estimated Fair Value	19,735	10,845
Less amounts classified as cash equivalents, Amortized Cost	(19,735)	(10,845)
Less amounts classified as cash equivalents, Estimated Fair Value	(19,735)	(10,845)
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	19,735	10,845
Available-for-sale securities, Estimated Fair Value	$ 19,735	$ 10,845

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Unrealized gain or loss on available-for-sale securities	$ 0	$ 0

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2017	Jan. 31, 2014
Biogen [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment		$ 2,500,000
Takeda License Agreements [Member] | License Agreement Terms [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization milestone payments payable			$ 9,200,000
Potential pre-commercialization payments receivable	$ 57,500,000
Contract assets	0
Received and recognized milestone revenue	$ 0

Notes Payable - Additional Info

Notes Payable - Additional Information (Detail)	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2017USD ($)Amendment$ / sharesshares
Debt Instrument [Line Items]
Outstanding principal balance of loan		$ 6,094,000
Subsequent Event [Member] | SVB [Member] | Loan Agreement [Member]
Debt Instrument [Line Items]
Borrowing amount	$ 5,500,000
Repayment of remaining obligations	5,900,000
Amended Loan Agreement [Member]
Debt Instrument [Line Items]
Number of loan amendments | Amendment			2
Debt instrument, Effective interest rate description		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.
Line of credit facility final payment, additional amount due			$ 312,500
Maturity date			Apr. 1, 2020
Outstanding principal balance of loan		$ 6,094,000
Warrants expiration term			5 years
Number of warrants issued | shares			208,002
Warrants exercise price for shares | $ / shares			$ 3.2454
Estimated fair value of warrants issued			$ 500,000
Loan, Covenant description		Pursuant to the Loan Agreement and the Amendments, the Company is bound during the term of the Loan Agreement and the Amendments by a variety of affirmative covenants, including, without limitation, certain information delivery requirements and notice requirements, and negative covenants, including, without limitation, restrictions on 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 and the Amendments (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. In the event of default by the Company, the Lenders would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the Loan Agreement and the Amendments, which could harm the Company's financial condition. The Company was in compliance with all applicable covenants set forth in the Loan Agreement and the Amendments as of March 31, 2019 and December 31, 2018. The principal payments due under the Loan Agreement and the Amendments have been classified as a current liability at December 31, 2018 due to the considerations discussed in Note 1 and the assessment that the material adverse change clause under the Loan Agreement and the Amendments is not within the Company's control. The Company has not been notified of an event of default by the Lenders as of the date of the filing of this Form 10-Q.
Amended Loan Agreement [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Repayment of remaining obligations	$ 5,900,000
Amended Loan Agreement [Member] | Extension of Maturity Date [Member]
Debt Instrument [Line Items]
Percentage of penalty for prepaying loan before maturity			0.50%
Amended Loan Agreement [Member] | Other Accrued Liabilities [Member]
Debt Instrument [Line Items]
Line of credit facility final payment accrued			$ 321,000
Amended 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 Agreement and the Amendments (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	[1]
Debt Instrument [Line Items]
Total notes payable as of March 31, 2019	$ 6,094
Less carrying amount of notes payable	(6,032)	$ (7,396)
Notes payable [Member]
Debt Instrument [Line Items]
2019	4,568
2020	2,231
Total minimum payments	6,799
Less amount representing interest	(705)
Less unamortized debt discount and issuance costs	$ (62)
[1]	The condensed consolidated balance sheet as of December 31, 2018, 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, 2018.

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2019	Jan. 31, 2019	Mar. 31, 2019
Underwritten Offering [Member]
Stockholders Equity [Line Items]
Shares of common stock issued		23,000,000
Proceeds from issuance of common and convertible preferred stock, gross		$ 20
Proceeds from issuance of common and convertible preferred stock, net		$ 18.6
Underwritten Offering [Member] | Series E Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares issued		17,000
Shares issued upon conversion		1,000
Numbers of shares converted			7,000
Preferred stock, shares outstanding	10,000		10,000
Underwritten Offering [Member] | Series E Convertible Preferred Stock [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock		9.98%
Underwritten Offering [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Price per common share		$ 0.50
Shares Issued upon conversion			7,000,000
Underwritten Offering [Member] | Preferred Stock [Member] | Series E Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share		$ 500
Controlled Equity Offering Facilities [Member]
Stockholders Equity [Line Items]
Issuance of common stock, remaining offering value	$ 43.6		$ 43.6
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Common stock, shares sold			0
CSPA [Member] | Aspire [Member] | Registration Rights Agreement [Member]
Stockholders Equity [Line Items]
Common stock, shares sold			0
Remaining purchase commitment	$ 10.9

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
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 417	$ 896
Employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	372	398
Non-employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	45	498
Research and development [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	156	164
General and administrative [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 216	$ 234

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Line Items]
Cash paid for operating lease liability	$ 0.1
ROU asset obtained in exchange for new operating lease liability	1.4
Rent expense	$ 0.1	$ 0.1
Original Operating Lease [Member]
Leases [Line Items]
Operating lease agreement, original date	2014-01
Fifth Amended Operating Lease [Member]
Leases [Line Items]
Lease expiration date	Jun. 30, 2021
Operating lease agreement, date of amendment	2017-12
Operating lease, property description	The lease was last amended in December 2017 to extend the expiration date to June 30, 2021, with an option to extend the lease for two additional years. The Company did not assume the option to extend the lease term in its determination of the lease term as the exercise of the option was not reasonable certain to exercise when the lease was last amended in December 2017.
Lessee, operating lease, existence of option to extend [true false]	true
Option to extend the lease	option to extend the lease for two additional years.
Operating lease, renewal term	2 years
Operating lease, remaining term	2 years 3 months 18 days

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Lease Liability (Detail) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2019	$ 424
2020	578
2021	294
Total rental payments	1,296
Less imputed interest	(70)
Present value of lease liability	$ 1,226

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2019	Dec. 31, 2017
Amended Loan Agreement [Member]
Subsequent Event [Line Items]
Maturity date		Apr. 1, 2020
Subsequent Event [Member] | Term Loan Agreement [Member] | Silicon Valley Bank [Member]
Subsequent Event [Line Items]
Borrowing amount	$ 5,500,000
Debt instrument, payment terms	Under the terms of the SVB Loan Agreement, the Company is required to make interest-only payments through December 31, 2020 on the borrowings at a floating rate equal to the greater of the Prime Rate minus 2.25%, as defined in the SVB Loan Agreement, or 3.25%, followed by an amortization period of 24 months of equal monthly payments of principal plus interest amounts until paid in full.
Debt instrument, frequency of periodic payment	monthly
Maturity date	Dec. 1, 2022
Debt instrument, interest-only payments date	Dec. 31, 2020
Debt instrument, stated interest rate	3.25%
Debt instrument, amortization period	24 months
Final payment fee, percentage	4.00%
Subsequent Event [Member] | Term Loan Agreement [Member] | Silicon Valley Bank [Member] | Prime Rate [Member]
Subsequent Event [Line Items]
Debt instrument, basis spread on floating rate	2.25%
Subsequent Event [Member] | Term Loan Agreement [Member] | Silicon Valley Bank [Member] | Prior to 1st Anniversary of April 26, 2019, or Effective Date [Member]
Subsequent Event [Line Items]
Prepayment fee	$ 165,000
Subsequent Event [Member] | Term Loan Agreement [Member] | Silicon Valley Bank [Member] | After 1st Anniversary but Prior to 2nd Anniversary of Effective Date [Member]
Subsequent Event [Line Items]
Prepayment fee	110,000
Subsequent Event [Member] | Term Loan Agreement [Member] | Silicon Valley Bank [Member] | After 2nd Anniversary of Effective Date [Member]
Subsequent Event [Line Items]
Prepayment fee	55,000
Subsequent Event [Member] | Amended Loan Agreement [Member]
Subsequent Event [Line Items]
Repayment of remaining obligations	$ 5,900,000
Subsequent Event [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Common stock, shares issued upon conversion of convertible preferred stock	4,950,165
Series B Convertible Preferred Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Numbers of shares converted	13,639
Shares outstanding	0
Series C Convertible Preferred Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Numbers of shares converted	1,558
Shares outstanding	0
Series D Convertible Preferred Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Numbers of shares converted	1,119
Shares outstanding	1,381
Series E Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Shares outstanding	10,000