Sienna Biopharmaceuticals (SNNAQ) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 06, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	Sienna Biopharmaceuticals, Inc.
Trading Symbol	SNNA
Entity Central Index Key	0001656328
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Shell Company	false
Entity Address, State or Province	CA
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		30,907,542

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 49,207	$ 48,526
Restricted cash	181	181
Prepaid expenses and other current assets	1,229	1,705
Total current assets	50,617	50,412
Property and equipment, net	237	311
Operating lease right-of-use asset	712
In-process research and development	45,172	45,594
Goodwill	10,887	10,989
Total assets	107,625	107,306
Current liabilities:
Accounts payable	1,522	2,792
Accrued personnel costs	1,945	3,057
Other accrued expenses	3,246	5,000
Contingent consideration, current portion	14,100	13,500
Total current liabilities	20,813	24,349
Contingent consideration—net of current portion	19,400	15,700
Operating lease liability—net of current portion	544
Long-term debt, net	29,474	30,125
Deferred tax liability	10,406	10,503
Other long-term liabilities	5	48
Total liabilities	80,642	80,725
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.0001 par value, 10,000 shares authorized, no shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively
Common stock, $0.0001 par value, 300,000 shares authorized, 30,732 and 21,177 shares issued and 30,534 and 20,870 outstanding at June 30, 2019 and December 31, 2018, respectively
Additional paid-in capital	208,261	182,750
Accumulated other comprehensive income	2,772	3,199
Accumulated deficit	(184,050)	(159,368)
Total stockholders' equity	26,983	26,581
Total liabilities and stockholders' equity	$ 107,625	$ 107,306

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	30,732,000	21,177,000
Common stock, shares outstanding	30,534,000	20,870,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 5,084	$ 15,692	$ 12,177	$ 28,672
General and administrative	2,643	5,976	11,389	11,473
Total operating expenses	7,727	21,668	23,566	40,145
Loss from operations	(7,727)	(21,668)	(23,566)	(40,145)
Other income (expense), net	(537)	1,429	(1,080)	2,803
Net loss	(8,264)	(20,239)	(24,646)	(37,342)
Other comprehensive income (loss):
Cumulative translation adjustment	586	(2,494)	(427)	(1,120)
Comprehensive loss	$ (7,678)	$ (22,733)	$ (25,073)	$ (38,462)
Per share information:
Net loss, basic and diluted	$ (0.27)	$ (1)	$ (0.90)	$ (1.84)
Basic and diluted weighted average shares outstanding	30,354	20,289	27,496	20,258

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2017	$ 91,199		$ 171,726	$ 5,370	$ (85,897)
Beginning Balance, Shares at Dec. 31, 2017		20,194
Vesting of early exercised shares	70		70
Vesting of early exercised shares, shares		60
Stock-based compensation expense	901		901
Repurchase of early exercised shares	(18)		(18)
Repurchase of early exercised shares, shares		(8)
Foreign currency translation adjustments	1,374			1,374
Net loss	(17,103)				(17,103)
Ending Balance at Mar. 31, 2018	76,423		172,679	6,744	(103,000)
Ending Balance, Shares at Mar. 31, 2018		20,246
Beginning Balance at Dec. 31, 2017	91,199		171,726	5,370	(85,897)
Beginning Balance, Shares at Dec. 31, 2017		20,194
Net loss	(37,342)
Ending Balance at Jun. 30, 2018	55,534		174,523	4,250	(123,239)
Ending Balance, Shares at Jun. 30, 2018		20,365
Beginning Balance at Dec. 31, 2017	91,199		171,726	5,370	(85,897)
Beginning Balance, Shares at Dec. 31, 2017		20,194
Ending Balance at Dec. 31, 2018	26,581		182,750	3,199	(159,368)
Ending Balance, Shares at Dec. 31, 2018		20,870
Beginning Balance at Mar. 31, 2018	76,423		172,679	6,744	(103,000)
Beginning Balance, Shares at Mar. 31, 2018		20,246
Vesting of early exercised shares	54		54
Vesting of early exercised shares, shares		52
Stock-based compensation expense	995		995
Issuance of common stock in connection with exercise of stock options	407		407
Issuance of common stock in connection with exercise of stock options, shares		37
Shares issued pursuant to the employee stock purchase plan	388		388
Shares issued pursuant to the employee stock purchase plan, shares		30
Foreign currency translation adjustments	(2,494)			(2,494)
Net loss	(20,239)				(20,239)
Ending Balance at Jun. 30, 2018	55,534		174,523	4,250	(123,239)
Ending Balance, Shares at Jun. 30, 2018		20,365
Beginning Balance at Dec. 31, 2018	26,581		182,750	3,199	(159,368)
Beginning Balance, Shares at Dec. 31, 2018		20,870
Cumulative effect of adoption of ASU 2016-02	(36)				(36)
Vesting of early exercised shares	56		56
Vesting of early exercised shares, shares		55
Stock-based compensation expense	1,533		1,533
Issuance of new shares	21,445		21,445
Issuance of new shares, shares		9,200
Issuance of warrants to purchase common stock	1,105		1,105
Repurchase of early exercised shares	(3)		(3)
Repurchase of early exercised shares, shares		(1)
Foreign currency translation adjustments	(1,013)			(1,013)
Net loss	(16,382)				(16,382)
Ending Balance at Mar. 31, 2019	33,286		206,886	2,186	(175,786)
Ending Balance, Shares at Mar. 31, 2019		30,124
Beginning Balance at Dec. 31, 2018	$ 26,581		182,750	3,199	(159,368)
Beginning Balance, Shares at Dec. 31, 2018		20,870
Issuance of common stock in connection with exercise of stock options, shares	0
Net loss	$ (24,646)
Ending Balance at Jun. 30, 2019	26,983		208,261	2,772	(184,050)
Ending Balance, Shares at Jun. 30, 2019		30,534
Beginning Balance at Mar. 31, 2019	33,286		206,886	2,186	(175,786)
Beginning Balance, Shares at Mar. 31, 2019		30,124
Vesting of early exercised shares	52		52
Vesting of early exercised shares, shares		54
Stock-based compensation expense	871		871
Issuance of new shares	425		425
Issuance of new shares, shares		329
Shares issued pursuant to the employee stock purchase plan	27		27
Shares issued pursuant to the employee stock purchase plan, shares		27
Foreign currency translation adjustments	586			586
Net loss	(8,264)				(8,264)
Ending Balance at Jun. 30, 2019	$ 26,983		$ 208,261	$ 2,772	$ (184,050)
Ending Balance, Shares at Jun. 30, 2019		30,534

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019
Common Stock [Member]
Issuance costs	$ 159	$ 1,555

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (24,646)	$ (37,342)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	76	78
Amortization of debt discount and issuance costs	470
Stock-based compensation	2,404	1,896
Fair value adjustment of success payment liability		(2,404)
Fair value adjustment of contingent consideration	4,300	2,300
Non-cash interest expense	428
Loss on disposal of property and equipment	2
Impairment of operating lease - right-of-use asset	13
Changes in assets and liabilities:
Prepaid expenses and other current assets	475	122
Accounts payable and other accrued liabilities	(4,708)	5,145
Net cash used in operating activities	(21,186)	(30,205)
Investing activities
Investment in property and equipment	(4)	(17)
Net cash used in investing activities	(4)	(17)
Financing activities
Proceeds from issuance of common stock, net of issuance costs, early exercise liability and repurchase of unvested early exercise stock options	21,867	389
Net proceeds from issuance of long-term debt (payment of debt issuance costs)	(16)	29,897
Proceeds from issuance of common stock upon ESPP purchase	27	388
Net cash provided by financing activities	21,878	30,674
Effect of exchange rate changes on cash	(7)	(32)
Net increase in cash, cash equivalents and restricted cash	681	420
Cash, cash equivalents and restricted cash at beginning of period	48,707	74,648
Cash, cash equivalents and restricted cash at end of period	49,388	$ 75,068
Supplemental Disclosure of Cash Flow Information:
Right-of-use asset obtained in exchange for lease liability	844
Warrants issued	$ 1,105

Organization and Description of

Organization and Description of Business	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Organization and Description of Business	1. Organization and Description of Business In these notes to the unaudited condensed consolidated financial statements, the “Company,” “Sienna,” “we,” “us,’” and “our” refers to Sienna Biopharmaceuticals, Inc. (formerly Sienna Labs, Inc.) and its subsidiaries on a consolidated basis. Sienna Biopharmaceuticals, Inc., was incorporated on July 27, 2010, under the laws of the State of Delaware and is headquartered in Westlake Village, California. The Company is a clinical-stage biopharmaceutical company focused on bringing unconventional scientific innovations to patients whose lives remain burdened by their disease. On August 5, 2019, the Company announced that it has retained Cowen and Company, LLC (“Cowen”) as an independent financial advisor to assist in exploring financial and strategic alternatives designed to maximize shareholder value. With Cowen’s assistance, the Company will continue to explore capital raising to enable the initiation of its planned Phase 3 pivotal clinical trials for its lead product candidate, SNA-120 (pegcantratinib), for psoriasis and the associated pruritus (itch), in addition to exploring a wide range of financial and strategic alternatives. The Company may be unable to identify or execute such financial or strategic alternatives, and even if executed, such financial or strategic alternatives may not enhance stockholder value or the Company’s financial position. The Company does not intend to initiate its planned Phase 3 clinical trials of SNA-120 until the Company secures sufficient additional capital. On June 29, 2018, the Company entered into a new loan and security agreement (the “SVB Loan Agreement”) with Silicon Valley Bank (“SVB”), pursuant to which SVB agreed to make available to the Company term loans with an aggregate principal amount of up to $40.0 million, $30.0 million of which was funded on June 29, 2018. On January 28, 2019, the Company entered into an amendment to the loan and security agreement, under which the Company’s total access to term loans is now $30.0 million, with additional minimum liquidity requirements. See Note 8, “Long-Term Debt.” On August 3, 2018 the Company entered into a sales agreement (the “Sales Agreement”) with Cowen, pursuant to which the Company may sell from time to time, at its option, up to $75.0 million of the Company’s common stock through an “at-the-market” equity offering program under which Cowen will act as sales agent (the “ATM Offering Program”). On August 3, 2018, the Company also filed a Registration Statement on Form S-3 (the “Shelf Registration Statement”), covering the offering of up to $250.0 million of common stock, preferred stock, debt securities, warrants, purchase contracts and units. The Shelf Registration Statement included a prospectus covering the offering, issuance and sale of up to $75.0 million of the Company’s common stock from time to time through the ATM Offering Program. The Registration Statement became effective on August 14, 2018. The shares to be sold under the Sales Agreement, may be issued and sold pursuant to the Shelf Registration Statement. During the year ended December 31, 2018, the Company issued 340,307 shares of its common stock through the ATM Offering Program and received net proceeds of approximately $5.0 million, after deducting commissions of $0.2 million and other offering expenses of $0.4 million. 329,588 0.4 18,000 0.1 On January 2, 2019, the Company implemented a corporate restructuring to focus resources on its lead product candidate, SNA-120 for psoriasis and the associated pruritus, resulting in a reduction in force to reduce operational costs and preserve capital. The restructuring resulted in an elimination of 20 positions. At March 31, 2019, the Company had completed the activities associated with the restructuring plan and all related payments had been made. In February 2019, the Company completed an underwritten public offering of 9,200,000 shares of common stock at a price to the public of $2.50 per share, including 1,200,000 shares of common stock pursuant to the underwriters’ option to purchase additional shares. The Company received net proceeds from the offering of approximately $21.4 million, after deducting the underwriters’ discounts and commissions and offering expenses payable by the Company. See Note 11, “Stockholders’ Equity.”

Liquidity Risks and Going Conce

Liquidity Risks and Going Concern	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Liquidity Risks and Going Concern	2. Liquidity Risks and Going Concern The Company has incurred operating losses and has an accumulated deficit as a result of ongoing efforts to develop product candidates, including conducting preclinical and clinical trials and providing general and administrative support for these operations. The Company had an accumulated deficit of $ 184.1 8.3 24.6 21.2 The Company had cash and cash equivalents of $ 49.2 30, 2019 and December 31, 2018, respectively. To alleviate the conditions that raise substantial doubt about the Company’s ability to continue as a going concern, the Company will be required to raise additional capital to fund future operations through the sale of its equity securities, incurring additional debt, entering into licensing or collaboration agreements with partners, grants or other sources of financing. There can be no . The Company has historically financed its operations primarily through private and public equity issuances and debt offerings, and more recently through term loans under the SVB Loan Agreement and proceeds from the Company’s ATM Offering Program. See Note 8, “Long-Term Debt.”

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	3. Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP, and the applicable rules and regulations of the Securities and Exchange Commission, or the SEC, regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted. Going Concern The accompanying unaudited condensed consolidated financial statements are prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and liquidation of liabilities in the normal course of business. Unaudited Condensed Consolidated Financial Statements The accompanying financial information for the three and six months ended June 30, 2019 and 2018 are unaudited. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position as of June 30, 2019 and its results of operations for the three and six months ended June 30, 2019 and 2018 and cash flows for the six months ended June 30, 2019 and 2018. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other period(s). Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of Sienna Biopharmaceuticals, Inc. and results of its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. For the three and six months ended June 30, 2019 and 2018, the subsidiaries’ net loss included in the Company’s consolidated statement of operations was $0.3 million and $0.7 million, and $1.5 million and $2.4 million, respectively. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. The most significant estimates in the Company’s consolidated financial statements relate to equity awards, warrants, clinical trial accruals and the valuation of contingent consideration obligations and the impairment assessment of the in-process research and development and goodwill incurred in connection with the acquisition of Creabilis plc, or Creabilis. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one one Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation. The reclassifications were not material to the unaudited condensed consolidated financial statements. Cash and Cash Equivalents The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, and obligations issued by U.S. government and U.S. government agencies, and places restrictions on maturities and concentration by type and issuer. The Company considers all highly liquid securities with original final maturities of three months or less from the date of purchase to be cash equivalents. As of June 30, 2019, cash and cash equivalents are comprised of funds in cash and U.S. Treasury money market funds. From time to time, the Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation. The accounts are monitored by management to mitigate the risk. Restricted Cash At June 30, 2019 and December 31, 2018, the Company held $0.2 million of restricted cash related to cash collateralized standby letters of credit in connection with obligations under the facility lease. Fair Value Measurements The Company’s financial instruments, in addition to those presented in Note 7, “Fair Value Measurements”, include restricted cash, accounts payable, accrued liabilities and long-term debt. The carrying amount of restricted cash, accounts payable and accrued liabilities approximate fair value because of the short-term nature of these instruments. Further, based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes the carrying amount of the long-term debt approximates its fair value. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets which range from three five no In-process Research and Development and Goodwill Intangible assets acquired in a business combination are recognized separately from goodwill and are initially recognized at their fair value at the acquisition date (which is regarded as their cost). Intangible assets related to acquired in-process research and development are treated as indefinite lived intangible assets and not amortized until they become definite lived assets upon regulatory approval. At that time, the Company will determine the useful life of the asset and begin amortization. Indefinite lived intangible assets are reviewed for impairment at least annually or if indicators of potential impairment exist. There were no Goodwill represents the excess of the purchase price over the estimated fair value of the identifiable assets acquired and liabilities assumed in a business combination. The Company evaluates goodwill for impairment annually and upon the occurrence of triggering events or substantive changes in circumstances that could indicate a potential impairment. An impairment loss is recognized when the fair value of the reporting unit to which the goodwill relates is below its carrying value. In determining the fair value utilized in the goodwill impairment assessment, the Company considered qualitative factors such as changes in strategy, cash flows, the regulatory environment, overall market conditions, as well as the market capitalization of the Company’s publicly traded common stock. The Company operates as a single reporting unit and estimates the fair value of its single reporting unit using the Company’s market capitalization plus an estimated control premium. Market capitalization is determined by multiplying the shares outstanding on the assessment date by the market price of the Company’s common stock. If it is determined through the impairment evaluation process that goodwill has been impaired, an impairment charge would be recorded in the consolidated statement of operations and comprehensive loss. The Company completed the impairment test and determined that there was no impairment. The Company’s share price is highly volatile and subsequent declines in the market share price could pose risks of impairment in the future. It is not possible at this time to determine if an impairment charge would result from these factors, or, if it does, whether such charge would be material. The Company will continue to monitor the recoverability of its goodwill. There was no Research and Development Costs Research and development costs are expensed as incurred. These costs include direct program expenses, which are payments made to third parties that specifically relate to the Company’s research and development, such as payments to clinical research organizations, clinical investigators, manufacturing of clinical material, pre-clinical testing and consultants. In addition, employee costs (salaries, payroll taxes, benefits, stock-based compensation and travel) for employees contributing to research and development activities are classified as research and development costs. Stock-Based Compensation The Company measures employee and director stock-based compensation expense for all stock-based awards at the grant date based on the fair value measurement of the award. The expense is recorded on a straight-line basis over the requisite service period, which is generally the vesting period, for the entire award. Expense is adjusted for actual forfeitures of unvested awards as they occur. The Company calculates the fair value measurement of stock options using the Black-Scholes valuation model. Prior to the adoption of a new accounting pronouncement on January 1, 2019 related to share-based payments issued to non-employees for goods or services, stock options issued to non-employees were valued on their grant date and remeasured at the current fair value at the end of each reporting period until they vested. Under the new guidance, the measurement of equity-classified non-employee awards is fixed at the grant date, and no longer remeasured. The Company estimates the fair value of restricted stock unit awards based on the closing price of the Company’s common stock on the date of issuance. Proceeds from options exercised by employees prior to vesting pursuant to an early exercise provision, the related shares of which the Company has the option to repurchase prior to the vesting date should employment of the early exercise holder be terminated, are recognized as a liability until the shares vest. Clinical Trial Accruals As part of the process of preparing its consolidated financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors and consultants and clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its rate of clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date in its consolidated financial statements based on the facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2019, there have been no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials. The Company’s clinical trial accrual is dependent in part upon the timely and accurate reporting of contract research organizations and other third-party vendors. Other accrued expenses include accrued clinical trial costs of $1.4 million and $2.3 million as of June 30, 2019 and December 31, 2018, respectively. Prepaid expenses and other current assets include prepaid clinical trial expenses of $0.7 million as of June 30, 2019. There were no prepaid clinical trial expenses as of December 31, 2018. Basic and Diluted Net Loss Per Common Share Basic net loss per common share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, excluding the effects of converting preferred stock, stock options and unvested restricted stock outstanding. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of shares of common stock outstanding during the period plus the potential dilutive effects of convertible preferred stock, convertible notes, stock options and unvested restricted stock outstanding during the period calculated in accordance with the treasury stock method but are excluded if their impact is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between the weighted average number of shares used to calculate basic and diluted net loss per common share for the three and six months ended June 30, 2019 and 2018. Shares excluded from the calculation were 3.8 Income Taxes The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred taxes are recognized based on the differences between financial statement and income tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company has provided a full valuation allowance on its deferred tax assets. The provision for income taxes represents the current tax payable for the period and the change during the period in deferred tax assets and liabilities. The Company recognizes the effect of an income tax position only if, based on its merits, the position is more likely than not to be sustained on audit by the taxing authorities. Interest and penalties related to uncertain tax positions are recorded as income tax expense. Other Comprehensive Income (Loss) Included in other comprehensive income (loss) for the three and six months ended June 30, 2019 and 2018 are an unrealized foreign currency translation gain of $ 0.6 0.4 $2.5 million and $1.1 million, respectively. This is the Company’s only component of other comprehensive income (loss) for the three and six months ended June 30, 2019 and 2018. Foreign currency translation The net assets of international subsidiaries where the local currencies have been determined to be the functional currencies are translated into U.S. dollars using current exchange rates. These include the entities acquired as part of the Creabilis acquisition. See Note 4, “Contingent Consideration”. As part of this transaction, the Company acquired entities in the United Kingdom, denominated in British pounds, and Italy and Luxembourg, denominated in euros. The U.S. dollar effects that arise from translating net assets of these subsidiaries at changing rates are recognized in other comprehensive income (loss) in the condensed consolidated balance sheet. The earnings or loss of these subsidiaries are translated into U.S. dollars using average exchange rates for the periods. Recently Issued Accounting Standards Accounting Pronouncements Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), which requires lessees to recognize most leases on the balance sheet. Lessees and lessors are required to apply the new standard at the beginning of the earliest period presented in the financial statements in which they first apply the new guidance, using a modified retrospective approach to adoption. The primary effect of adoption is the requirement to record right-of-use assets and corresponding lease obligations for current operating leases. The requirements of this standard generally include a significant increase in required disclosures. The FASB subsequently issued the following amendments to ASU 2016-02, which have the same effective date and transition date of January 1, 2019: • ASU No. 2018-10, Codification Improvements to Topic 842, Leases , which amends certain narrow aspects of the guidance issued in ASU 2016-02; and • ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component. On January 1, 2019, the Company adopted ASC 842, which resulted in the recognition of right-of-use assets of approximately $0.8 million and related lease liabilities on the consolidated balance sheets of approximately $1.0 million related to its operating lease commitments, with no material impact to the opening balance of retained earnings. The Company adopted the new leasing standards using the modified retrospective transition approach, applying to leases existing as of, or entered into after, January 1, 2019. Prior periods were not adjusted. The new standard provides a number of optional practical expedients in transition. The Company has elected the package of practical expedients to not reassess prior conclusions about lease identification under the new standard, lease classification, and initial direct costs. The Company also elected the practical expedient allowing the use of hindsight in determining the lease term and assessing impairment of right-of-use assets based on all facts and circumstances through the effective date of the new standard. The new standard also provides practical expedients for ongoing lease accounting, including electing the recognition exemption for short-term leases for all leases that qualify. Under this exemption, the Company did not recognize right-of-use, assets or lease liabilities for those leases that qualify as a short-term lease (leases with lease terms of 12 months or less), which includes not recognizing right-of-use assets or lease liabilities for existing short-term leases in transition. The Company also elected the practical expedient to not separate lease and non-lease components for all leases. In June 2018 the FASB issued ASU 2018-07, “ Compensation —Stock Compensation (Topic 718) —Improvements to Nonemployee Share-Based Payment Accounting” (“ASU 2018-07”), which expands the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. The amendments in ASU 2018-07 are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company adopted this standard on January 1, 2019 with no impact on the consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, “ Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income”, which provides the option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The Company adopted this standard on January 1, 2019 with no impact on the consolidated financial statements. Accounting Pronouncements Not Yet Adopted 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 . This new standard modifies certain disclosure requirements on fair value measurements. This new standard will be effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company does not expect the adoption of this new standard to have a significant impact on its disclosures.

Contingent Consideration

Contingent Consideration	6 Months Ended
	Jun. 30, 2019
Business Combinations [Abstract]
Contingent Consideration	4. Contingent Consideration In December 2016, the Company entered into a Share Purchase Agreement, or the Purchase Agreement, to acquire the entire issued share capital of Creabilis. Pursuant to the acquisition of Creabilis, the Company obtained SNA-120, SNA-125 and the related intellectual property. SNA-120 is a first-in-class inhibitor of Tropomyosin receptor kinase A (TrkA) for the treatment of psoriasis, as well as the associated pruritus. SNA-125 is a topical dual Janus kinase 3 (JAK3)/TrkA inhibitor being developed for the treatment of various inflammatory conditions, including atopic dermatitis, psoriasis and the associated pruritus. Upon closing, Creabilis became a direct wholly-owned subsidiary. As part of the terms of the acquisition, the Company agreed to make contingent payments up to an aggregate of $58.0 million in a combination of cash and stock upon the achievement of certain development and approval milestones, of which $5.0 million has been previously satisfied. Upon the commencement of the first Phase 3 clinical trial of SNA-120, the Company will become obligated to issue $18.0 million in shares of common stock, less certain offsets if applicable, to the former Creabilis shareholders. In addition, the Company is obligated to make certain contingent payments up to an aggregate of $80.0 million in cash upon the achievement of certain annual net sales thresholds and one-time royalties of less than 1% of the amount by which annual net sales exceeds each threshold in the year such threshold is achieved. Where milestone payments are required to be paid in stock, the number of shares will be determined based on the volume weighted average price of the common stock as reported on the Nasdaq Global Select Market, (“Nasdaq”), for the preceding 20-day trading period. The agreement to pay the future milestones and potential one-time royalties resulted in the recognition of a contingent consideration liability, which is recognized at the inception of the transaction. Other than these payments, subsequent changes to the estimated amounts of contingent consideration to be paid are recognized in the consolidated statement of operations in general and administrative expense. The fair value of the contingent consideration is determined using preliminary cash flow projections, based on estimated timing and probabilities around the achievement of certain development, approval and sales milestones, expected product sales and other assumptions. The fair value of the contingent consideration was determined to be $ 33.5

Identifiable Intangible Assets

Identifiable Intangible Assets	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Identifiable Intangible Assets	5. Identifiable Intangible Assets The Company’s only identifiable intangible assets were in-process research and development related to SNA-120 and SNA-125 as of June 30, 2019 and December 31, 2018. The total intangible in-process research and development assets were recorded at an initial value of $42.3 million as a result of the Company’s acquisition of Creabilis, are foreign denominated and subject to translation, and had a carrying value of $45.2 million and $45.6 million as of June 30, 2019 and December 31, 2018, respectively. The Company used the income approach to determine the fair value of the in-process research and development assets. This approach calculated fair value by estimating future cash flows attributable to the assets, using several unobservable inputs such as future revenues and expenses, time and resources needed to complete development and probabilities of obtaining market approval, and then discounting these cash flows to a present value using a risk-adjusted discount rate commensurate with the Company’s cost of capital and expectation of the revenue growth for products at their life cycle stage. These inputs are considered Level 3 inputs under the fair value measurements and disclosure guidance. See Note 7, “Fair Value Measurements”. Identifiable intangible assets are initially measured at their respective fair values and will not be amortized until commercialization. If commercialization occurs, intangible assets will be amortized over their estimated useful lives. In-process research and development assets were initially recognized at their fair value as determined on the date of acquisition of December 6, 2016 and are reviewed for impairment at least annually or whenever changes in circumstances indicate a potential impairment or upon regulatory approval resulting in the reclassification to a finite-lived intangible asset. No

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	6. Property and Equipment Property and equipment consisted of the following as of June 30, 2019 and December 31, 2018 (in thousands): Estimated Useful Life (in years) June 30, 2019 December 31, 2018 Lab equipment 5 $ 307 $ 307 Computer hardware 3 119 142 Capital lease equipment 3 46 46 Furniture and fixtures 5 87 87 Software 3 9 9 Leasehold improvements 105 105 Total 673 696 Less accumulated depreciation (436 ) (385 ) Property and equipment, net $ 237 $ 311 Leasehold improvements are depreciated over the shorter of the lease term or the estimated useful life of the related asset. Depreciation expense was $ 38,000 76,000 $ 39 78

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	7. Fair Value Measurements The Company determines the fair value of financial and nonfinancial assets and liabilities using the fair value hierarchy, which describes three levels of inputs that may be used to measure fair value, as follows: Level 1 —Quoted prices in active markets for identical assets or liabilities; Level 2 —Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. These inputs either represent quoted prices for similar assets in active markets or have been derived from observable market data; and Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs reflect the Company’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities based on the best information available in the circumstances. In certain cases where there is limited activity or less transparency around inputs to valuation, assets are classified as Level 3 within the valuation hierarchy. The following tables set forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 Level 1 Level 2 Level 3 Assets: Cash equivalents $ 49,207 $ — $ — Total $ 49,207 $ — $ — Liabilities: Contingent consideration $ — $ — $ 33,500 Total $ — $ — $ 33,500 December 31, 2018 Level 1 Level 2 Level 3 Assets: Cash equivalents $ 48,526 $ — $ — Total $ 48,526 $ — $ — Liabilities: Contingent consideration $ — $ — $ 29,200 Total $ — $ — $ 29,200 The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Balance at December 31, 2018 $ 29,200 Change in fair value due to remeasurement 4,300 Balance at June 30, 2019 $ 33,500 Cash equivalents At June 30, 2019, the Company’s cash equivalents are comprised of U.S. Treasury money market funds whose value is based upon quoted market prices in active markets for identical assets or liabilities with no adjustments applied. Accordingly, these investments are classified as Level 1 of the fair value measurements and disclosure guidance. Intangible assets In connection with the acquisition of Creabilis, the Company acquired intangible in-process research and development assets which were recorded at fair value based on significant unobservable (Level 3) inputs. The fair value of in-process research and development (“IPR&D”) assets was determined by an independent third-party valuation firm applying the income approach. This approach calculates fair value by estimating future cash flows attributable to the IPR&D assets using several significant unobservable inputs, including a risk adjusted discount rate commensurate with the perceived risk of the IPR&D assets of 20.5%, projected future revenues and expenses based on the cumulative probabilities of multiple scenarios with individual probabilities ranging from 0.1% to 22.5%, and estimates of the timing of the achievement of the various product development, regulatory approval and sales milestones. These intangible assets are not measured at fair value on a recurring basis but are subject to fair value measurement as part of the related impairment test. Warrants In connection with the amendment to the SVB Loan Agreement, the Company issued warrants to purchase shares of the Company’s common stock. Based upon the characteristics and provisions of the warrants, they were classified as equity and recorded at their fair value as of the date of issuance. The estimated fair value of the warrants was calculated using the Black-Scholes option-pricing model, using a term of 10 years, an estimated volatility of 78.02%, a risk-free interest rate of 2.75% and an expected dividend yield of 0%. The warrants are not measured at fair value on a recurring basis. Contingent consideration In connection with the acquisition of Creabilis, the Company agreed to pay additional amounts based on the achievement of certain development, approval and sales milestones. The valuation of contingent consideration uses assumptions the Company believes would be made by a market participant. The Company assesses these estimates on an on-going basis as additional data impacting the assumptions is obtained. Contingent consideration may change significantly as development progresses and additional data is obtained, impacting the Company’s assumptions regarding probabilities of successful achievement of related milestones used to estimate the fair value of the liability and the timing in which they are expected to be achieved. In evaluating the fair value information, judgment is required to interpret the market data used to develop the estimates. The estimates of fair value may not be indicative of the amounts that could be realized in a current market exchange. Accordingly, the use of different market assumptions and/or different valuation techniques could result in materially different fair value estimates. The fair value of the contingent consideration was determined by an independent third-party valuation firm applying the income approach. This approach calculates fair value by estimating future cash flows attributable to the related IPR&D assets using several significant unobservable inputs, including risk adjusted discount rates ranging from 5.3% to 15.9%, projected future revenues and expenses based on the cumulative probabilities of multiple scenarios with individual probabilities ranging from 3.6 52.6 The change in value during the three and six months ended June 30, 2019 was a decrease of $ 0.3 4.3 $0.8 million and $2.3 million, respectively. The increases were primarily related to the passage of time, changes in probabilities of success, and progress toward milestone dates as well as changes in external market factors. There were no

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Long-Term Debt	8. Long-Term Debt On June 29, 2018 the Company entered into the SVB Loan Agreement with SVB. Under the SVB Loan Agreement, SVB initially provided the Company with access to term loans in an aggregate principal amount of up to $ 40.0 30.0 June 29, 2018 July 1, 2023 July 31, 2020 The Company may prepay the outstanding principal balance of the term loans advanced by SVB in whole but not in part, subject to a prepayment fee ranging from 1.0% to 3.0% of any amount prepaid, depending upon when the prepayment occurs. The Company will also pay a final payment fee equal to 6.50% of the total term loans advanced, due upon the earliest of maturity, acceleration, prepayment or termination of the SVB Agreement. If unrestricted cash at SVB falls below the greater of (i) $ 30.0 15.0 15.0 15.0 15.0 8.0 In connection with the amendment, the Company issued to SVB and its affiliate, Life Science Loans II, LLC, warrants to purchase an aggregate of 535,714 shares of the Company’s common stock at an exercise price of $2.80 per share. The warrants are immediately exercisable and have a term of ten Under the terms of the SVB Loan Agreement, the Company granted first priority liens and security interests in substantially all of the Company’s assets (excluding all of its intellectual property, which is subject to a negative pledge) and a pledge of the shares of one of its wholly-owned subsidiaries as collateral for the obligations thereunder. The SVB Loan Agreement also contains representations and warranties by the Company and SVB and indemnification provisions in favor of SVB and customary covenants (including limitations on other indebtedness, liens, acquisitions, and investments and dividends), and events of default (including payment defaults, breaches of covenants following any applicable cure period, a material impairment in the perfection or priority of SVB’s security interest in the collateral, and events relating to bankruptcy or insolvency). As of June 30, 2019, the carrying value of the term loan consists of $30.0 million principal outstanding less the debt issuance costs of approximately $ 0.1 1.1 Interest expense relating to the term loan for the three and six months ended June 30, 2019 was $ 0.8 1.6 10.9 Future principal payments for the long-term debt are as follows (in thousands): June 30, 2019 2019 — 2020 4,500 2021 9,586 2022 10,393 2023 5,521 Total principal payments 30,000 Final fee due at maturity in 2023 1,950 Total principal and final fee payments 31,950 Unamortized discount, debt issuance costs and warrants (2,476 ) Long-term debt, net $ 29,474

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Operating Lease In May 2016, the Company entered into a 40-month operating lease obligation for office space in Westlake Village, California (“Suite 140”), which commenced on October 10, 2016, and terminates on February 29, 2020 three In June 2017, the Company amended the lease agreement to include an additional 5,973 square feet (“Suite 215”) and an allowance for leasehold improvements of up to $0.1 million. In March 2019, the Company subleased Suite 215 and received an upfront payment of $0.1 million for rental income on the sublease. The lease and sublease terminate concurrently on February 29, 2020. The Company does not plan on exercising a renewal option for Suite 215. On January 1, 2019, the Company adopted ASC 842, which resulted in the recognition of right-of-use (“ROU”) assets of approximately $0.8 million and related lease liabilities in the consolidated balance sheets of approximately $1.0 million related to its operating lease commitments. ROU assets represent the Company’s right to control an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As most of its leases do not provide an implicit rate, the Company used its incremental borrowing rate based on the information available at the commencement date in determining the discount rate used to present value the lease payments. At January 1, 2019, the discount rate used to present value the lease payments was 12.5%. The Company’s leases typically do not include any residual value guarantees, bargain purchase options, or asset retirement obligations. In March 2019, in connection with the sublease of Suite 215, the Company evaluated the ROU asset for impairment. Because the lease payments for Suite 215 exceeded the sublease income over the remaining lease term, the Company recorded an impairment charge of $13,000 to write-down the ROU asset to the fair value of the sublease income over the remaining term. As of June 30, 2019 the balance of the ROU asset was $ 0.7 0.8 0.5 0.3 72,000 Total operating lease expense for the three and six months ended June 30, 2019 was $ 0.1 0.2 27,000 36,000 Supplemental cash flow information for the six months ended June 30, 2019 related to operating leases is as follows (in thousands): Six Months Ended June 30, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 215 Right-of-use assets obtained in exchange for lease liabilities – operating leases $ 844 As of June 30, 2019, the maturities of the Company’s operating lease liabilities are as follows (in thousands): 2019 (remaining six months) $ 217 2020 272 2021 239 2022 239 2023 40 Total operating lease payments 1,007 Less: imputed interest (174 ) Total operating lease liabilities $ 833 As of June 30, 2019, the weighted average remaining lease term for the company’s operating leases was 3.2 License and Supply Agreement The Company has an amended and restated exclusive license agreement with nanoComposix, pursuant to which the Company owes minimum annual royalties of $50,000 or low single digit royalties on net sales of licensed products. Success Payment Liability In October 2015, the Company entered into a letter agreement with certain stockholders pursuant to which the Company agreed to make success payments to such stockholders. The agreement ends on its fifth anniversary in October 2020. Success payments are payable in cash or common stock at the Company’s sole discretion and will be owed in the event that the value of its common stock meets or exceeds certain specified share price thresholds on certain specified dates during the success payment period. Each success payment and the associated share price threshold is ascending from $10.0 million payable at a share price threshold of $53.71 per share to $35.0 million payable at $71.61 per share and with a maximum payment of $60.0 million at a share price threshold of $107.42 per share. Each success payment is inclusive of any preceding payments, if previously made, such that the success payments to stockholders will not exceed $60.0 million in the aggregate. Upon their issuance, the success payments did not require any future service to be provided by the recipients and as such, the success payments were accounted for under accounting guidance for derivatives and hedging. Accordingly, the Company recorded an initial liability at fair value and remeasured the liability each reporting period, with changes being recognized in the consolidated statement of operations in other income and expense. The fair value of the success payments liability was estimated based on a third-party valuation using a model which simulates the future movement of stock prices based on several key variables. As of June 30, 2019 and December 31, 2018, the success payment liability was immaterial. During the three and six months ended June 30, 2018, the Company recorded other income of $1.2 million and $2.4 million, respectively, due to remeasurement of the liability. There was no Indemnifications The Company has indemnification obligations to its directors and executive officers for specified events or occurrences, subject to certain limits, while the directors and executive officers are serving at the Company’s request in such capacities. There have been no Contingencies From time to time, the Company may be subject to various litigation and related matters arising in the ordinary course of business, including those set forth in Part II, Item 1 “Legal Proceedings”. As of June 30, 2019, there are no matters where there is at least a reasonable possibility that a material loss has been or will be incurred.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	10. Related Party Transactions Venvest Biotech, LLC Dr. Beddingfield, the Company’s President and Chief Executive Officer and a member of the Company’s board of directors, is an advisor to Venvest Biotech, LLC, or Venvest, and is considered a non-managing member of Venvest. Dr. Beddingfield has an economic interest in any gain associated with the shares of the Company’s capital stock purchased by Venvest in the Company’s Series A-3 and Series B Preferred Stock financings. On May 17, 2018, Dr. Beddingfield acquired 47,594 shares pursuant to a mandatory distribution from Venvest, resulting from the economic gain associated with those shares. Dr. Beddingfield has resigned from his advisory role, is no longer a member of Venvest, and has no management or voting rights in respect of Venvest. Stock Purchase Rights In January 2016, in connection with his commencement of employment with the Company, the Company’s board of directors granted Dr. Beddingfield, the Company’s President and Chief Executive Officer, the right to purchase 553,652 shares of the Company’s common stock for a purchase price of $2.35 per share, which the board of directors determined was the fair market value on the date of grant. With respect to 454,912 shares subject to the stock purchase right, 25% of the shares vest on the first anniversary of the grant, and 1/48th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date. With respect to 49,370 shares subject to the stock purchase right, 50% of the shares vest on the first date the volume-weighted average trading price of the Company’s common stock equals or exceeds $71.03 per share, and 1/24th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date. With respect to the remaining 49,370 shares subject to the stock purchase right, 50% of the shares vest upon achievement of a milestone related to clinical development, and 1/24th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date. On December 3, 2018, 50% of these shares vested as a result of achieving the clinical development milestone relating to the top-line results from the Phase 2b study of SNA-120 for the treatment of itch and psoriasis. The Company determined that the stock purchase rights effectively represented an option and the fair value of the option was $1.3 million which is being amortized as compensation expense over the performance period of the award with $ 0.1 0.2 In May 2016, Dr. Beddingfield exercised his stock purchase rights in full and purchased restricted stock that vests on the same schedule as the stock purchase rights. As of December 31, 2018, 0.4 million shares subject to the award had vested, and an additional 63,036 Success Payments Todd Harris, a member of the Company’s board of directors, is a beneficiary of the Success Payments Agreement, as described in Note 9 “Commitments and Contingencies—Success Payment Liability” and will receive 25.22% of any related payouts.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2019
Federal Home Loan Banks [Abstract]
Stockholders' Equity	11. Stockholders’ Equity As of June 30, 2019, the authorized stock of the Company was 300.0 million shares of common stock, $0.0001 par value per share, and 10.0 million shares of preferred stock, $0.0001 par value per share. Common Stock Holders of common stock are entitled to one vote per share and, upon liquidation, dissolution, or winding up of the Company, are entitled to receive all assets available for distribution to stockholders. The holders have no preemptive or other subscription rights and there are no redemption or sinking fund provisions with respect to such shares. Shares of common stock reserved for future issuance are as follows (in thousands): June 30, 2019 Common stock awards outstanding 2,822 Restricted stock units outstanding 745 Common stock awards available for grant under employee benefit plans 1,091 Common stock warrants outstanding 536 Total shares of common stock reserved for future issuance 5,194 Convertible Preferred Stock As of June 30, 2019 and December 31, 2018, there was no convertible preferred stock outstanding. ATM Offering Program In August 2018, the Company entered into a sales agreement with Cowen pursuant to which the Company may sell from time to time, at its option, up to $75.0 million of the Company’s common stock through ATM Offering Program, under which Cowen will act as sales agent. The aggregate compensation payable to Cowen shall be 3% of the gross sales price of the common stock sold by Cowen pursuant to the Sales Agreement. During the year ended December 31, 2018, the Company issued 340,307 shares of its common stock through its ATM Offering Program and received net proceeds of approximately $5.0 million, after deducting commissions of $0.2 million and other offering expenses of $0.4 million. During the three and six months ended June 30, 2019, the Company issued an additional 329,588 shares of its common stock and received net proceeds of approximately $0.4 million, after deducting commissions of $18,000 and other offering expenses of $0.1 million. Stock Awards and Stock-Based Compensation In July 2017, the Company’s board of directors approved the 2017 Incentive Award Plan, or the 2017 Plan, which became effective upon the completion of the IPO on August 1, 2017. The 2017 Plan serves as the successor incentive award plan to the Company’s 2010 Equity Incentive Plan, or the 2010 Plan, and has 0.6 The terms of awards pursuant to the 2017 Plan are determined by the administrator of the 2017 Plan. The 2017 Plan is administered by the compensation committee of the Company’s board of directors unless the Company’s board of directors assumes authority for administration. In addition, the Company’s board of directors has delegated authority to grant awards to employees other than executive officers and certain senior executives of the Company to a committee consisting of the Company’s chief executive officer. Stock options granted pursuant to the 2017 Plan must have an exercise price of not less than the fair market value of the Company’s common stock on the date of grant, except that incentive stock options granted to an individual who owns (or is deemed to own) at least 10% of the total combined voting power of all classes of the Company’s capital stock (a “10% Holder”), must have an exercise price of at least 110% of the fair market value of a share of common stock on the date of grant. Stock options granted under the 2017 Plan generally expire ten years from the date of the grant, except that incentive stock options granted to a 10% Holder must not be exercisable after five years from the date of grant. The Company’s stock awards under the 2017 Plan vest based on terms in the stock award agreements and generally vest over four years. Following the Company’s IPO and in connection with the effectiveness of the Company’s 2017 Plan, the 2010 Plan terminated and no further awards will be granted under that plan. However, all outstanding awards under the 2010 Plan will continue to be governed by their existing terms. The fair value of each employee award granted during 2019 and 2018 was estimated on the grant date using the Black-Scholes option-pricing model. Prior to the adoption of a new accounting pronouncement on January 1, 2019 related to share-based payments issued to non-employees for goods or services, the fair value of each non-employee option granted was estimated on the grant date using the Black-Scholes option-pricing model and subsequently remeasured each reporting period. Under the new guidance, the measurement of equity-classified non-employee awards is fixed at the grant date, and no longer remeasured. The Company estimates the fair value of restricted stock unit awards based on the closing price of the Company’s common stock on the date of issuance. In determining the fair value of stock options granted, the following weighted average assumptions were used in the Black-Scholes option-pricing model for awards granted for the six months ended June 30, 2019 and the year ended December 31, 2018. Six Months Ended June 30, 2019 Year Ended December 31, 2018 Expected stock price volatility 69.91–75.27% 65.40–74.21% Expected dividend yield —% —% Expected term (in years) 2.0–5.6 5.0–6.1 Risk-free interest rate 2.03%–2.52% 2.55–3.06% Due to limited historical data, the Company estimates stock price volatility based on a combined weighted average of the Company’s historical average volatility and that of a selected peer group of comparable publicly traded companies over the expected life of the award. The Company has never paid and does not expect to pay dividends in the foreseeable future. The expected term represents the average time that awards that vest are expected to be outstanding. For employee awards that have an early exercise provision, the Company has sufficient information to utilize four years as an expected term. For awards without an early exercise provision, the Company does not have sufficient history of stock option exercises to estimate the expected term and, thus, calculates expected term using the simplified method, based on the midpoint between the average vesting date and the contractual term. For all non-employees, the expected term is equivalent to the contractual term of 10 years. The risk-free interest rate is based on the United States Treasury yield curve for the expected life of the option. For awards issued prior to the listing of the Company’s common stock on Nasdaq, the fair value of the common stock utilized in the fair value estimation of award arrangements has been determined by the Company’s board of directors, utilizing contemporaneous third-party valuations. Following the listing of the common stock on Nasdaq, the Company uses its closing stock price as reported on Nasdaq on the grant date for the fair value of its stock. The Company has elected to record forfeitures as they occur and does not adjust its expense based on an estimated forfeiture rate. Stock Options The table below summarizes the stock option activity for the six months ended June 30, 2019: Number of Shares (in thousands) Weighted Average Exercise Price Per Share Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 2,263 $ 12.42 $ — Granted 1,155 2.18 Exercised — — — Cancelled (596 ) 12.82 Outstanding at June 30, 2019 2,822 $ 8.21 $ — Exercisable at June 30, 2019 988 $ 8.38 $ — Restricted Stock Units (RSUs) The table below summarizes the RSU activity for the six months ended June 30, 2019: Number of RSUs (in thousands) Weighted Average Grant Date Fair Value Unvested at December 31, 2018 — $ — Granted 816 2.32 Vested — — Cancelled (71 ) 2.32 Unvested balance at June 30, 2019 745 $ 2.32 The Company did not grant any non-employee options to purchase shares of its common stock during the six months ended June 30, 2019 and 2018. Total compensation cost recorded in the condensed consolidated statements of operations and comprehensive loss, which includes non-cash stock-based compensation expense, restricted shares issued to non-employees subject to vesting and the value of stock options issued to non-employees for services and non-cash stock-based compensation expense relating to the ESPP are allocated as follows (in thousands): Three months ended June 30, Six months ended June 30, 2019 2018 2019 2018 Research and development $ 429 $ 287 $ 843 $ 730 General and administrative 442 708 1,561 1,166 $ 871 $ 995 $ 2,404 $ 1,896 As of June 30, 2019, there was $10.0 million of unrecognized compensation expense related to unvested employee stock award agreements, which is expected to be recognized over a weighted-average period of approximately 2.54 The weighted-average grant date fair value of all stock options granted during the six months ended June 30, 2019 was $ 1.67 8.8 3.2 20,000 62,000 Prior to its termination in connection with the effectiveness of the 2017 Plan, the 2010 Plan allowed the Company to grant to employees the right to exercise stock options in exchange for cash before the requisite service was provided (e.g., before the award is vested under its original terms); however, such arrangements permit the Company to subsequently repurchase such shares at the exercise price if the employee ceases to be a service provider. Such an exercise is not substantive for accounting purposes. Therefore, the payment received for the exercise price is recognized as an early exercise liability in the consolidated balance sheets and will be transferred to common stock and additional paid-in capital as such shares vest. As of June 30, 2019 and December 31, 2018, 197,971 0.1 0.1 2,000 Warrants In January 2019, in connection with the amendment to the SVB Loan Agreement, the Company issued warrants to purchase an aggregate of 535,714 shares of the Company’s common stock at an exercise price of $2.80 per share. Based upon the characteristics and provisions of the warrants, they were classified as equity and recorded at their fair value as of the date of issuance of $1.1 million to additional paid-in capital, with no further adjustments to their valuation. The estimated fair value of the warrants was calculated using the Black-Scholes option-pricing model, using assumptions that are based on the individual characteristics of the warrants on the valuation date, as well as assumptions for expected volatility, expected life, yield and risk-free interest rate. 2017 Employee Stock Purchase Plan The Company adopted the 2017 Employee Stock Purchase Plan, or the ESPP, which became effective upon the completion of the IPO on August 1, 2017. The ESPP is designed to allow the Company’s eligible employees to purchase shares of the Company’s common stock, at semi-annual intervals, with their accumulated payroll deductions. Under the ESPP, participants are offered the option to purchase shares of the Company’s common stock at a discount during a series of successive offering periods. The option purchase price will be the lower of 85% of the closing trading price per share of the Company’s common stock on the first trading date of an offering period in which a participant is enrolled or 85% of the closing trading price per share on the purchase date, which will occur on the last trading day of each offering period. The Company began the first offering period on December 31, 2017. The ESPP is intended to qualify under Section 423 of the U.S. Internal Revenue Service Code of 1986, as amended. The maximum number of the Company’s common stock which will be authorized for sale under the ESPP is equal to the sum of (a) 198,883 1 3.0 The Company recognized $0.1 million in compensation expense related to the ESPP for the three and six months ended June 30, 2019, and $0.1 million and $0.2 million for the three and six months ended June 30, 2018, respectively. As of December 31, 2018, 67,508 shares of common stock were issued under the ESPP, and an additional 26,886

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes There is no The Company has evaluated the available evidence supporting the realization of its deferred tax assets, including the amount and timing of future taxable income, and has determined that it is more likely than not that its net deferred tax assets will not be realized in the United States and certain foreign jurisdictions. Due to uncertainties surrounding the realization of the deferred tax assets, the Company maintains a full valuation allowance against substantially all deferred tax assets. When the Company determines that it will be able to realize some portion or all of its deferred tax assets, an adjustment to its valuation allowance on its deferred tax assets would have the effect of increasing net income in the period such determination is made. As of June 30, 2019, the Company does not have any accrued interest or penalties related to uncertain tax positions. The Company’s policy is to recognize interest and penalties related to uncertain tax positions in income tax expense. The Company is subject to U.S. federal tax authority and U.S. state tax authority examinations for all years with the net operating loss and credit carryforwards.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events On August 5, 2019, the Company announced that it has retained Cowen as an independent financial advisor to assist in exploring financial and strategic alternatives designed to maximize shareholder value. With Cowen’s assistance, the Company will continue to explore capital raising to enable the initiation of its planned Phase 3 pivotal clinical trials for its lead product candidate, SNA-120, for psoriasis and the associated pruritus, in addition to exploring a wide range of financial and strategic alternatives. The Company may be unable to identify or execute such financial or strategic alternatives, and even if executed, such financial or strategic alternatives may not enhance stockholder value or the Company’s financial position. The Company does not intend to initiate its planned Phase 3 clinical trials of SNA-120 until the Company secures sufficient additional capital. On August 1, 2019, in order to retain and incentivize current employees, the Company’s Board of Directors approved a repricing of 1,854,462 stock options held by current employees granted prior to August 1, 2019. The options had exercise prices between $2.32 and $20.53 per share, which were reduced to $0.71, the closing price of the Company’s common stock as of August 6, 2019. There were no modifications to the vesting schedules of the previously issued options. The repricing of the options will be treated as a modification for accounting purposes and any incremental compensation expense for vested stock options calculated using the Black-Scholes option-pricing model will be recorded in the consolidated statement of operations and comprehensive loss for the quarter ending September 30, 2019. The incremental expense together with the unamortized expense remaining on any unvested options will be amortized over the remaining vesting periods.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP, and the applicable rules and regulations of the Securities and Exchange Commission, or the SEC, regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted.
Going Concern	Going Concern The accompanying unaudited condensed consolidated financial statements are prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and liquidation of liabilities in the normal course of business.
Unaudited Condensed Consolidated Financial Statements	Unaudited Condensed Consolidated Financial Statements The accompanying financial information for the three and six months ended June 30, 2019 and 2018 are unaudited. The unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position as of June 30, 2019 and its results of operations for the three and six months ended June 30, 2019 and 2018 and cash flows for the six months ended June 30, 2019 and 2018. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other period(s).
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of Sienna Biopharmaceuticals, Inc. and results of its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. For the three and six months ended June 30, 2019 and 2018, the subsidiaries’ net loss included in the Company’s consolidated statement of operations was $0.3 million and $0.7 million, and $1.5 million and $2.4 million, respectively.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. The most significant estimates in the Company’s consolidated financial statements relate to equity awards, warrants, clinical trial accruals and the valuation of contingent consideration obligations and the impairment assessment of the in-process research and development and goodwill incurred in connection with the acquisition of Creabilis plc, or Creabilis. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one one
Reclassifications	Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation. The reclassifications were not material to the unaudited condensed consolidated financial statements.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, and obligations issued by U.S. government and U.S. government agencies, and places restrictions on maturities and concentration by type and issuer. The Company considers all highly liquid securities with original final maturities of three months or less from the date of purchase to be cash equivalents. As of June 30, 2019, cash and cash equivalents are comprised of funds in cash and U.S. Treasury money market funds. From time to time, the Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation. The accounts are monitored by management to mitigate the risk.
Restricted Cash	Restricted Cash At June 30, 2019 and December 31, 2018, the Company held $0.2 million of restricted cash related to cash collateralized standby letters of credit in connection with obligations under the facility lease.
Fair Value Measurements	Fair Value Measurements The Company’s financial instruments, in addition to those presented in Note 7, “Fair Value Measurements”, include restricted cash, accounts payable, accrued liabilities and long-term debt. The carrying amount of restricted cash, accounts payable and accrued liabilities approximate fair value because of the short-term nature of these instruments. Further, based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes the carrying amount of the long-term debt approximates its fair value.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets which range from three five no
In-process Research and Development and Goodwill	In-process Research and Development and Goodwill Intangible assets acquired in a business combination are recognized separately from goodwill and are initially recognized at their fair value at the acquisition date (which is regarded as their cost). Intangible assets related to acquired in-process research and development are treated as indefinite lived intangible assets and not amortized until they become definite lived assets upon regulatory approval. At that time, the Company will determine the useful life of the asset and begin amortization. Indefinite lived intangible assets are reviewed for impairment at least annually or if indicators of potential impairment exist. There were no Goodwill represents the excess of the purchase price over the estimated fair value of the identifiable assets acquired and liabilities assumed in a business combination. The Company evaluates goodwill for impairment annually and upon the occurrence of triggering events or substantive changes in circumstances that could indicate a potential impairment. An impairment loss is recognized when the fair value of the reporting unit to which the goodwill relates is below its carrying value. In determining the fair value utilized in the goodwill impairment assessment, the Company considered qualitative factors such as changes in strategy, cash flows, the regulatory environment, overall market conditions, as well as the market capitalization of the Company’s publicly traded common stock. The Company operates as a single reporting unit and estimates the fair value of its single reporting unit using the Company’s market capitalization plus an estimated control premium. Market capitalization is determined by multiplying the shares outstanding on the assessment date by the market price of the Company’s common stock. If it is determined through the impairment evaluation process that goodwill has been impaired, an impairment charge would be recorded in the consolidated statement of operations and comprehensive loss. The Company completed the impairment test and determined that there was no impairment. The Company’s share price is highly volatile and subsequent declines in the market share price could pose risks of impairment in the future. It is not possible at this time to determine if an impairment charge would result from these factors, or, if it does, whether such charge would be material. The Company will continue to monitor the recoverability of its goodwill. There was no
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. These costs include direct program expenses, which are payments made to third parties that specifically relate to the Company’s research and development, such as payments to clinical research organizations, clinical investigators, manufacturing of clinical material, pre-clinical testing and consultants. In addition, employee costs (salaries, payroll taxes, benefits, stock-based compensation and travel) for employees contributing to research and development activities are classified as research and development costs.
Stock-Based Compensation	Stock-Based Compensation The Company measures employee and director stock-based compensation expense for all stock-based awards at the grant date based on the fair value measurement of the award. The expense is recorded on a straight-line basis over the requisite service period, which is generally the vesting period, for the entire award. Expense is adjusted for actual forfeitures of unvested awards as they occur. The Company calculates the fair value measurement of stock options using the Black-Scholes valuation model. Prior to the adoption of a new accounting pronouncement on January 1, 2019 related to share-based payments issued to non-employees for goods or services, stock options issued to non-employees were valued on their grant date and remeasured at the current fair value at the end of each reporting period until they vested. Under the new guidance, the measurement of equity-classified non-employee awards is fixed at the grant date, and no longer remeasured. The Company estimates the fair value of restricted stock unit awards based on the closing price of the Company’s common stock on the date of issuance. Proceeds from options exercised by employees prior to vesting pursuant to an early exercise provision, the related shares of which the Company has the option to repurchase prior to the vesting date should employment of the early exercise holder be terminated, are recognized as a liability until the shares vest.
Clinical Trial Accruals	Clinical Trial Accruals As part of the process of preparing its consolidated financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors and consultants and clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate trial expenses in its consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its rate of clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date in its consolidated financial statements based on the facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2019, there have been no material adjustments to the Company’s prior period estimates of accrued expenses for clinical trials. The Company’s clinical trial accrual is dependent in part upon the timely and accurate reporting of contract research organizations and other third-party vendors. Other accrued expenses include accrued clinical trial costs of $1.4 million and $2.3 million as of June 30, 2019 and December 31, 2018, respectively. Prepaid expenses and other current assets include prepaid clinical trial expenses of $0.7 million as of June 30, 2019. There were no prepaid clinical trial expenses as of December 31, 2018.
Basic and Diluted Net Loss Per Common Share	Basic and Diluted Net Loss Per Common Share Basic net loss per common share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, excluding the effects of converting preferred stock, stock options and unvested restricted stock outstanding. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of shares of common stock outstanding during the period plus the potential dilutive effects of convertible preferred stock, convertible notes, stock options and unvested restricted stock outstanding during the period calculated in accordance with the treasury stock method but are excluded if their impact is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between the weighted average number of shares used to calculate basic and diluted net loss per common share for the three and six months ended June 30, 2019 and 2018. Shares excluded from the calculation were 3.8
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred taxes are recognized based on the differences between financial statement and income tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company has provided a full valuation allowance on its deferred tax assets. The provision for income taxes represents the current tax payable for the period and the change during the period in deferred tax assets and liabilities. The Company recognizes the effect of an income tax position only if, based on its merits, the position is more likely than not to be sustained on audit by the taxing authorities. Interest and penalties related to uncertain tax positions are recorded as income tax expense.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Included in other comprehensive income (loss) for the three and six months ended June 30, 2019 and 2018 are an unrealized foreign currency translation gain of $ 0.6 0.4 $2.5 million and $1.1 million, respectively. This is the Company’s only component of other comprehensive income (loss) for the three and six months ended June 30, 2019 and 2018.
Foreign currency translation	Foreign currency translation The net assets of international subsidiaries where the local currencies have been determined to be the functional currencies are translated into U.S. dollars using current exchange rates. These include the entities acquired as part of the Creabilis acquisition. See Note 4, “Contingent Consideration”. As part of this transaction, the Company acquired entities in the United Kingdom, denominated in British pounds, and Italy and Luxembourg, denominated in euros. The U.S. dollar effects that arise from translating net assets of these subsidiaries at changing rates are recognized in other comprehensive income (loss) in the condensed consolidated balance sheet. The earnings or loss of these subsidiaries are translated into U.S. dollars using average exchange rates for the periods.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Pronouncements Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), which requires lessees to recognize most leases on the balance sheet. Lessees and lessors are required to apply the new standard at the beginning of the earliest period presented in the financial statements in which they first apply the new guidance, using a modified retrospective approach to adoption. The primary effect of adoption is the requirement to record right-of-use assets and corresponding lease obligations for current operating leases. The requirements of this standard generally include a significant increase in required disclosures. The FASB subsequently issued the following amendments to ASU 2016-02, which have the same effective date and transition date of January 1, 2019: • ASU No. 2018-10, Codification Improvements to Topic 842, Leases , which amends certain narrow aspects of the guidance issued in ASU 2016-02; and • ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component. On January 1, 2019, the Company adopted ASC 842, which resulted in the recognition of right-of-use assets of approximately $0.8 million and related lease liabilities on the consolidated balance sheets of approximately $1.0 million related to its operating lease commitments, with no material impact to the opening balance of retained earnings. The Company adopted the new leasing standards using the modified retrospective transition approach, applying to leases existing as of, or entered into after, January 1, 2019. Prior periods were not adjusted. The new standard provides a number of optional practical expedients in transition. The Company has elected the package of practical expedients to not reassess prior conclusions about lease identification under the new standard, lease classification, and initial direct costs. The Company also elected the practical expedient allowing the use of hindsight in determining the lease term and assessing impairment of right-of-use assets based on all facts and circumstances through the effective date of the new standard. The new standard also provides practical expedients for ongoing lease accounting, including electing the recognition exemption for short-term leases for all leases that qualify. Under this exemption, the Company did not recognize right-of-use, assets or lease liabilities for those leases that qualify as a short-term lease (leases with lease terms of 12 months or less), which includes not recognizing right-of-use assets or lease liabilities for existing short-term leases in transition. The Company also elected the practical expedient to not separate lease and non-lease components for all leases. In June 2018 the FASB issued ASU 2018-07, “ Compensation —Stock Compensation (Topic 718) —Improvements to Nonemployee Share-Based Payment Accounting” (“ASU 2018-07”), which expands the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. The amendments in ASU 2018-07 are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company adopted this standard on January 1, 2019 with no impact on the consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, “ Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income”, which provides the option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The Company adopted this standard on January 1, 2019 with no impact on the consolidated financial statements. Accounting Pronouncements Not Yet Adopted 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 . This new standard modifies certain disclosure requirements on fair value measurements. This new standard will be effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company does not expect the adoption of this new standard to have a significant impact on its disclosures.

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2019
Property, Plant and Equipment [Abstract]
Components of Property and Equipment	Property and equipment consisted of the following as of June 30, 2019 and December 31, 2018 (in thousands): Estimated Useful Life (in years) June 30, 2019 December 31, 2018 Lab equipment 5 $ 307 $ 307 Computer hardware 3 119 142 Capital lease equipment 3 46 46 Furniture and fixtures 5 87 87 Software 3 9 9 Leasehold improvements 105 105 Total 673 696 Less accumulated depreciation (436 ) (385 ) Property and equipment, net $ 237 $ 311

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The following tables set forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 Level 1 Level 2 Level 3 Assets: Cash equivalents $ 49,207 $ — $ — Total $ 49,207 $ — $ — Liabilities: Contingent consideration $ — $ — $ 33,500 Total $ — $ — $ 33,500 December 31, 2018 Level 1 Level 2 Level 3 Assets: Cash equivalents $ 48,526 $ — $ — Total $ 48,526 $ — $ — Liabilities: Contingent consideration $ — $ — $ 29,200 Total $ — $ — $ 29,200
Summary of Changes in Fair Value of Level 3 Financial Liabilities	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Balance at December 31, 2018 $ 29,200 Change in fair value due to remeasurement 4,300 Balance at June 30, 2019 $ 33,500

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Schedule of Future Principal Payments for Long-term Debt	Future principal payments for the long-term debt are as follows (in thousands): June 30, 2019 2019 — 2020 4,500 2021 9,586 2022 10,393 2023 5,521 Total principal payments 30,000 Final fee due at maturity in 2023 1,950 Total principal and final fee payments 31,950 Unamortized discount, debt issuance costs and warrants (2,476 ) Long-term debt, net $ 29,474

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Operating Leases	Supplemental cash flow information for the six months ended June 30, 2019 related to operating leases is as follows (in thousands): Six Months Ended June 30, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 215 Right-of-use assets obtained in exchange for lease liabilities – operating leases $ 844
Schedule of Maturities of Operating Lease Liabilities	As of June 30, 2019, the maturities of the Company’s operating lease liabilities are as follows (in thousands): 2019 (remaining six months) $ 217 2020 272 2021 239 2022 239 2023 40 Total operating lease payments 1,007 Less: imputed interest (174 ) Total operating lease liabilities $ 833

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2019
Federal Home Loan Banks [Abstract]
Summary of Shares of Common Stock Reserved for Future Issuance	Shares of common stock reserved for future issuance are as follows (in thousands): June 30, 2019 Common stock awards outstanding 2,822 Restricted stock units outstanding 745 Common stock awards available for grant under employee benefit plans 1,091 Common stock warrants outstanding 536 Total shares of common stock reserved for future issuance 5,194
Summary of Assumptions Used for Grant Date Fair Value	In determining the fair value of stock options granted, the following weighted average assumptions were used in the Black-Scholes option-pricing model for awards granted for the six months ended June 30, 2019 and the year ended December 31, 2018. Six Months Ended June 30, 2019 Year Ended December 31, 2018 Expected stock price volatility 69.91–75.27% 65.40–74.21% Expected dividend yield —% —% Expected term (in years) 2.0–5.6 5.0–6.1 Risk-free interest rate 2.03%–2.52% 2.55–3.06%
Summary of Stock Option Activity	The table below summarizes the stock option activity for the six months ended June 30, 2019: Number of Shares (in thousands) Weighted Average Exercise Price Per Share Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 2,263 $ 12.42 $ — Granted 1,155 2.18 Exercised — — — Cancelled (596 ) 12.82 Outstanding at June 30, 2019 2,822 $ 8.21 $ — Exercisable at June 30, 2019 988 $ 8.38 $ —
Schedule of Nonvested Restricted Stock Units Activity	The table below summarizes the RSU activity for the six months ended June 30, 2019: Number of RSUs (in thousands) Weighted Average Grant Date Fair Value Unvested at December 31, 2018 — $ — Granted 816 2.32 Vested — — Cancelled (71 ) 2.32 Unvested balance at June 30, 2019 745 $ 2.32
Summary of Non-cash Stock-based Compensation Expense	Total compensation cost recorded in the condensed consolidated statements of operations and comprehensive loss, which includes non-cash stock-based compensation expense, restricted shares issued to non-employees subject to vesting and the value of stock options issued to non-employees for services and non-cash stock-based compensation expense relating to the ESPP are allocated as follows (in thousands): Three months ended June 30, Six months ended June 30, 2019 2018 2019 2018 Research and development $ 429 $ 287 $ 843 $ 730 General and administrative 442 708 1,561 1,166 $ 871 $ 995 $ 2,404 $ 1,896

Organization and Description _2

Organization and Description of Business - Additional Information (Detail)	Jan. 02, 2019Positions	Feb. 28, 2019USD ($)$ / sharesshares	Jun. 30, 2019USD ($)shares	Jun. 30, 2019USD ($)shares	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)shares	Jan. 28, 2019USD ($)	Aug. 31, 2018USD ($)	Aug. 03, 2018USD ($)	Jun. 29, 2018USD ($)
Organization And Description Of Business [Line Items]
Principal outstanding			$ 30,000,000	$ 30,000,000
Restructuring and related cost, number of positions eliminated | Positions	20
Net proceeds from offering after deducting the underwriters' discounts and commissions and offering expenses				$ 21,867,000	$ 389,000
Term Loan [Member]
Organization And Description Of Business [Line Items]
Debt instrument aggregate principal amount							$ 30,000,000
Term Loan [Member] | Silicon Valley Bank [Member]
Organization And Description Of Business [Line Items]
Debt instrument aggregate principal amount										$ 40,000,000
Principal outstanding										$ 30,000,000
Underwritten Public Offering [Member]
Organization And Description Of Business [Line Items]
Common stock shares issued | shares		9,200,000
Common stock price per share | $ / shares		$ 2.50
Over-Allotment Option [Member]
Organization And Description Of Business [Line Items]
Common stock shares issued | shares		1,200,000
Net proceeds from offering after deducting the underwriters' discounts and commissions and offering expenses		$ 21,400,000
ATM Offering Program [Member]
Organization And Description Of Business [Line Items]
Common stock shares issued | shares			329,588	329,588		340,307
Proceeds from issuance of common stock, net			$ 400,000	$ 400,000		$ 5,000,000
Issuance of common stock, commissions paid			18,000	18,000		200,000
Issuance of common stock, other offering expenses			$ 100,000	$ 100,000		$ 400,000
ATM Offering Program [Member] | Cowen [Member]
Organization And Description Of Business [Line Items]
Amount which can be raised under ATM offering program								$ 75,000,000	$ 75,000,000
Shelf Registration Statement [Member] | Maximum [Member]
Organization And Description Of Business [Line Items]
Aggregate registered amount									$ 250,000,000

Liquidity Risks and Going Con_2

Liquidity Risks and Going Concern- Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Liquidity Risks and Going Concern [Abstract]
Accumulated deficit	$ (184,050)				$ (184,050)		$ (159,368)
Net losses	(8,264)	$ (16,382)	$ (20,239)	$ (17,103)	(24,646)	$ (37,342)
Net cash used in operating activities					$ (21,186)	$ (30,205)
Substantial doubt about going concern, within one year					false
Cash and cash equivalents	$ 49,207				$ 49,207		$ 48,526

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Detail) shares in Millions	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Jun. 30, 2019USD ($)Segmentshares	Jun. 30, 2018USD ($)shares	Dec. 31, 2018USD ($)	Jan. 01, 2019USD ($)
Significant Accounting Policies [Line Items]
Net loss	$ (8,264,000)	$ (16,382,000)	$ (20,239,000)	$ (17,103,000)	$ (24,646,000)	$ (37,342,000)
Number of operating segment | Segment					1
Number of reportable segment | Segment					1
Impairments charge					$ 0		$ 0
Impairments of intangible assets					0		0
Impairment of goodwill					0		0
Accrued clinical trial costs	1,400,000				$ 1,400,000		2,300,000
Shares excluded from calculation of earnings per share | shares					3.8	2.5
Unrealized foreign currency translation gains and (losses)	600,000		(2,500,000)		$ (400,000)	$ (1,100,000)
Operating lease liability	833,000				833,000			$ 1,000,000
Right-of-use assets	712,000				712,000			$ 800,000
Prepaid Clinical Trial Costs					700,000		0
Subsidiaries [Member]
Significant Accounting Policies [Line Items]
Net loss	300,000		$ 1,500,000		$ 700,000	$ 2,400,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of asset					3 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of asset					5 years
Standby Letters of Credit [Member]
Significant Accounting Policies [Line Items]
Cash collateral for borrowed securities	$ 200,000				$ 200,000		$ 200,000

Contingent Consideration - Addi

Contingent Consideration - Additional Information (Detail) - Creabilis [Member] - USD ($) $ in Millions	Dec. 06, 2016	Jun. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Potential contingent milestone payments	$ 18
Payment for contingent consideration	5
Maximum [Member]
Business Acquisition [Line Items]
Royalty percentage		1.00%
Contingent Consideration [Member]
Business Acquisition [Line Items]
Fair value of contingent consideration in acquisition		$ 33.5	$ 29.2
Development and Approval Milestones [Member]
Business Acquisition [Line Items]
Business combination, aggregate contingent consideration	58
Net Sales Thresholds and One Time Royalties [Member]
Business Acquisition [Line Items]
Business combination, aggregate contingent consideration	$ 80

Identifiable Intangible Assets

Identifiable Intangible Assets - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Dec. 06, 2016
Indefinite-lived Intangible Assets [Line Items]
In-process research and development intangible assets, carrying value	$ 45,172,000	$ 45,594,000
In-process Research and Development Intangible Assets [Member]
Indefinite-lived Intangible Assets [Line Items]
Impairment recognized on identifiable intangible assets	$ 0	$ 0
In-process Research and Development Intangible Assets [Member]
Indefinite-lived Intangible Assets [Line Items]
Identifiable intangible assets, initial value recorded			$ 42,300,000

Property and Equipment - Compon

Property and Equipment - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 673	$ 696
Less accumulated depreciation	(436)	(385)
Property and equipment, net	$ 237	311
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	5 years
Property, plant and equipment, gross	$ 307	307
Computer Hardware [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	3 years
Property, plant and equipment, gross	$ 119	142
Capital Lease Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	3 years
Property, plant and equipment, gross	$ 46	46
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	5 years
Property, plant and equipment, gross	$ 87	87
Software [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life (in years)	3 years
Property, plant and equipment, gross	$ 9	9
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 105	$ 105

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 38	$ 39	$ 76	$ 78

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Level 1 [Member]
Assets:
Cash equivalents	$ 49,207	$ 48,526
Total	49,207	48,526
Level 3 [Member]
Liabilities:
Financial liabilities fair value	33,500	29,200
Contingent Consideration [Member] | Level 3 [Member]
Liabilities:
Financial liabilities fair value	$ 33,500	$ 29,200

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Level 3 Financial Liabilities (Detail) - Contingent Consideration [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			$ 29,200
Change in fair value due to remeasurement	$ (300)	$ 800	4,300	$ 2,300
Ending balance	$ 33,500		$ 33,500

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value transfer amount			$ 0		$ 0
Measurement Input, Option Volatility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrant	0.7802		0.7802
Measurement Input, Risk Free Interest Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrant	0.275		0.275
Measurement Input, Expected Dividend Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrant	0		0
Measurement Input, Expected Term [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrant,term	10 years		10 years
Creabilis [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration measurement input	0.053		0.053
Creabilis [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration measurement input	0.159		0.159
Creabilis [Member] | Probability of Multiple Scenarios [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration measurement input	0.036		0.036
Creabilis [Member] | Probability of Multiple Scenarios [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration measurement input	0.526		0.526
In-process Research and Development Intangible Assets [Member] | Creabilis [Member] | Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible asset measurement input	0.205		0.205
In-process Research and Development Intangible Assets [Member] | Creabilis [Member] | Probability of Multiple Scenarios [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible asset measurement input	0.001		0.001
In-process Research and Development Intangible Assets [Member] | Creabilis [Member] | Probability of Multiple Scenarios [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible asset measurement input	0.225		0.225
Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value	$ (300,000)	$ 800,000	$ 4,300,000	$ 2,300,000

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail) - USD ($)	Jun. 29, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jan. 28, 2019
Debt Instrument [Line Items]
Principal outstanding		$ 30,000,000		$ 30,000,000
Silicon Valley Bank [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Term loan, aggregate principal amount	$ 40,000,000				$ 30,000,000
Term loan, first credit extension	$ 30,000,000
Term loan, initiation date				Jun. 29, 2018
Term loan, maturity date				Jul. 1, 2023
Term loan, interest-only period end date				Jul. 31, 2020
Final payment in percentage		6.50%		6.50%
Unrestricted cash threshold amount		$ 30,000,000		$ 30,000,000
Term loan, covenant description				If unrestricted cash at SVB falls below the greater of (i) $30.0 million and (ii) the sum of (x) $15.0 million, plus (y) the Company’s six month cash burn, tested monthly as of the last day of each month, then the Company has the option to either (a) prepay the term loans in denominations of $15.0 million (plus accrued and unpaid interest, the final payment fee in respect to the portion of the terms loans being repaid and the prepayment fee in respect to the pro rata portion of the term loans being prepaid in excess of $15.0 million) or (b) immediately cash secure not less than the lesser of the outstanding balance or $15.0 million of the principal balance of all outstanding indebtedness under the term loans.
Prepayment of term loans				$ 15,000,000
Amount of cash secured of the principal balance of outstanding loans				$ 15,000,000
Interest rate percentage		8.00%		8.00%
Warrants issued to purchase common stock		535,714		535,714
Warrant exercise price		$ 2.80		$ 2.80
Warrant term				10 years
Principal outstanding		$ 30,000,000		$ 30,000,000
Debt issuance costs		100,000		100,000
Final maturity payment		2,000,000		2,000,000
Warrants and right outstanding		1,100,000		1,100,000
Interest expense		$ 800,000	$ 8,000,000	$ 1,600,000
Effective interest rate		10.90%		10.90%
Silicon Valley Bank [Member] | Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Prepayment fee in percentage				1.00%
Interest rate percentage		7.25%		7.25%
Silicon Valley Bank [Member] | Term Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Prepayment fee in percentage				3.00%
Final payment fee percentage		6.50%		6.50%
Silicon Valley Bank [Member] | Term Loan [Member] | Prime Rate [Member]
Debt Instrument [Line Items]
Interest rate percentage, spread on variable rate				2.50%

Long-Term Debt - Schedule of Fu

Long-Term Debt - Schedule of Future Principal Payments for Long-term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Long-term Debt, Fiscal Year Maturity [Abstract]
2019	$ 0
2020	4,500
2021	9,586
2022	10,393
2023	5,521
Total principal payments	30,000
Final fee due at maturity in 2023	1,950
Total principal and final fee payments	31,950
Unamortized discount, debt issuance costs and warrant	(2,476)
Long-term debt, net	$ 29,474	$ 30,125

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2016	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)$ / shares	Jun. 30, 2018USD ($)	Jan. 01, 2019USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2017USD ($)ft²
Other Commitments [Line Items]
Operating lease expiry date				Feb. 29, 2020
Upfront payment received				$ 100,000
Right of use asset		$ 712,000		712,000		$ 800,000
Operating lease liability		833,000		833,000		$ 1,000,000
Discount rate used to present value lease payments						12.50%
Operating lease impairment charges				13,000
Long-term		544,000		544,000
Short-term		300,000		300,000
Prepaid rent liability		72,000		72,000
Operating lease expense		100,000		200,000
Sublease income		$ 27,000		$ 36,000
Weighted-average remaining operating lease term		3 years 2 months 12 days		3 years 2 months 12 days
Success payment liability threshold one				$ 10,000,000
Success payment liability threshold one per share | $ / shares				$ 53.71
Success payment liability threshold two				$ 35,000,000
Success payment liability threshold two per share | $ / shares				$ 71.61
Success payment liability threshold maximum				$ 60,000,000
Success payment liability threshold maximum per share | $ / shares				$ 107.42
Aggregate success payment maximum				$ 60,000,000
Other Income [Member] | Success Payment Liabilities [Member]
Other Commitments [Line Items]
Change in fair value due to re-measurement recorded income (expense)		$ 0	$ 1,200,000	0	$ 2,400,000
Directors And Officers Liability Insurance [Member]
Other Commitments [Line Items]
Indemnification claims		0		0
Accrued indemnification liabilities		0		0			$ 0
Accounting Standards Update 2016-02 [Member]
Other Commitments [Line Items]
Cumulative effect of adoption of ASU 2016-02						$ 36,000
Lease Arrangement - Office Space in Westlake Village, California [Member]
Other Commitments [Line Items]
Operating lease obligation period	40 months
Operating lease renewal term	3 years
Operating lease expiry date	Feb. 29, 2020
Amended Lease Arrangement - Office Space in Westlake Village, California [Member]
Other Commitments [Line Items]
Additional area of office space leased | ft²								5,973
Minimum [Member]
Other Commitments [Line Items]
Annual royalties		$ 50,000		$ 50,000
Maximum [Member] | Amended Lease Arrangement - Office Space in Westlake Village, California [Member]
Other Commitments [Line Items]
Additional allowance for leasehold improvements								$ 100,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Operating Leases (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 215
Right-of-use assets obtained in exchange for lease liabilities - operating leases	$ 844

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Maturities of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Leases [Abstract]
2019 (remaining six months)	$ 217
2020	272
2021	239
2022	239
2023	40
Total operating lease payments	1,007
Less: imputed interest	(174)
Total operating lease liabilities	833	$ 1,000
Total operating lease payments	$ 1,007

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Dec. 03, 2018	May 17, 2018	Jan. 31, 2016	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Number of nonvested shares				197,971		197,971		307,504
Recognized compensation expense					$ 100	$ 2,404	$ 1,896
Number of shares vested						0
Notes Receivable [Member]
Related Party Transaction [Line Items]
Principal balance and interest forgiven on promissory note									$ 1,300
Dr.Beddingfield [Member]
Related Party Transaction [Line Items]
Stock issued during period shares acquisitions		47,594
President and Chief Executive Officer [Member] | Stock Purchase Rights [Member]
Related Party Transaction [Line Items]
Number of shares granted under stock purchase rights			553,652
Purchase price of common stock			$ 2.35
Recognized compensation expense				$ 100		$ 200
Number of shares vested						63,036		400,000
President and Chief Executive Officer [Member] | Share-based Compensation Award, Tranche One [Member] | Stock Purchase Rights [Member]
Related Party Transaction [Line Items]
Number of nonvested shares			454,912
Vesting condition description						25% of the shares vest on the first anniversary of the grant, and 1/48th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date.
Percentage of shares vest on first anniversary			25.00%
Percentage of shares vest monthly thereafter			2.00%
President and Chief Executive Officer [Member] | Share-based Compensation Award, Tranche Two [Member] | Stock Purchase Rights [Member]
Related Party Transaction [Line Items]
Number of nonvested shares			49,370
Vesting condition description						50% of the shares vest on the first date the volume-weighted average trading price of the Company's common stock equals or exceeds $71.03 per share, and 1/24th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date.
Percentage of shares vest monthly thereafter			4.00%
Percentage of shares vesting			50.00%
Minimum vesting share price			$ 71.03
President and Chief Executive Officer [Member] | Share-based Compensation Award, Tranche Three [Member] | Stock Purchase Rights [Member]
Related Party Transaction [Line Items]
Number of nonvested shares			49,370
Vesting condition description						50% of the shares vest upon achievement of a milestone related to clinical development, and 1/24th of the shares vest monthly thereafter, subject to Dr. Beddingfield continuing to provide services to the Company through each such vesting date.
Percentage of shares vest monthly thereafter			4.00%
Percentage of shares vesting	50.00%		50.00%
Todd Harris [Member]
Related Party Transaction [Line Items]
Success payments liability related payouts percentage						25.22%

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Class of Stock Disclosures [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shares of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Jun. 30, 2019	Dec. 31, 2018
Class of Stock Disclosures [Abstract]
Common stock awards outstanding	2,822	2,263
Restricted stock units outstanding	745
Common stock awards available for grant under employee benefit plans	1,091
Common stock warrants outstanding	536
Total shares of common stock reserved for future issuance	5,194

Stockholders' Equity - Converti

Stockholders' Equity - Convertible Preferred Stock - Additional Information (Detail) - shares	Jun. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Preferred stock, shares outstanding	0	0
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	0	0

Stockholders' Equity - ATM Offe

Stockholders' Equity - ATM Offering Program - Additional Information (Detail) - ATM Offering Program [Member] - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Aug. 31, 2018	Aug. 03, 2018
Class of Stock [Line Items]
Issuance of common stock	329,588	329,588	340,307
Proceeds from issuance of common stock, net	$ 400,000	$ 400,000	$ 5,000,000
Issuance of common stock, commissions paid	18,000	18,000	200,000
Issuance of common stock, other offering expenses	$ 100,000	$ 100,000	$ 400,000
Cowen [Member]
Class of Stock [Line Items]
Amount which can be raised under ATM offering program				$ 75,000,000	$ 75,000,000
Stock issuance costs under sales agreement as a percent of gross proceeds				3.00%

Stockholders' Equity - Stock Aw

Stockholders' Equity - Stock Awards and Stock-Based Compensation - Additional Information (Detail) - USD ($)	Aug. 01, 2017	Jan. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jul. 31, 2017
Class of Stock [Line Items]
Common stock available for issuance under plan			5,194,000			5,194,000
Number of shares granted to non-employee						1,155,000
Unrecognized compensation expense related to unvested employee stock award			$ 10,000,000			$ 10,000,000
Unrecognized compensation expense related to unvested employee stock award, recognized period						2 years 6 months 14 days
Weighted-average grant date fair value of stock options granted						$ 1.67
Weighted-average remaining contractual life of options outstanding						8 years 9 months 18 days
Fair value of shares vested						$ 3,200,000
Stock compensation expense related to non-employee option grants			$ 20,000		$ 100,000	$ 62,000	$ 300,000
Unvested shares			197,971			197,971		307,504
Early exercise liability related to unvested shares			$ 100,000			$ 100,000		$ 300,000
Early exercise liability related to unvested shares, current			100,000			100,000		200,000
Early exercise liability related to unvested shares, non-current			2,000			2,000		$ 100,000
Adjustments to additional paid in capital warrant issued				$ 1,105,000
Recognized compensation expense			871,000		995,000	$ 2,404,000	1,896,000
Silicon Valley Bank [Member] | Warrant [Member]
Class of Stock [Line Items]
Warrants issued to purchase common stock		535,714
Warrant exercise price		$ 2.80
Adjustments to additional paid in capital warrant issued		$ 1,100,000
2017 Incentive Award Plan [Member]
Class of Stock [Line Items]
Common stock available for issuance under plan									600,000
Incentive award plan, description						The 2017 Plan serves as the successor incentive award plan to the Company’s 2010 Equity Incentive Plan, or the 2010 Plan, and has X.X million shares of common stock available at June 30, 2019 for issuance pursuant to a variety of stock-based compensation awards, including stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards and other stock-based awards, plus shares of common stock that were reserved for issuance pursuant to future awards under the 2010 Plan at the time the 2017 Plan became effective, plus shares represented by awards outstanding under the 2010 Plan that are forfeited or lapse unexercised and which following the effective date of the 2017 Plan are not issued under the 2010 Plan. In addition, the 2017 Plan reserve increased on January 1, 2018 and 2019 and will increase further on each subsequent anniversary through 2027, by an amount equal to the lesser of (a) four percent of the shares of stock outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (b) such smaller number of shares of stock as determined by our board of directors; provided, however, that no more than 12.0 million shares of stock may be issued upon the exercise of incentive stock options.
2010 Equity Incentive Plan [Member]
Class of Stock [Line Items]
Stock awards expiration period						10 years
Stock awards vesting period						4 years
2017 Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Common stock available for issuance under plan	500,000
Number of authorized shares of common stock under ESPP	198,883
Common stock shares outstanding percentage	1.00%
Employee stock purchase price closing trading price	85.00%
Employee stock purchase plan, description						The maximum number of the Company’s common stock which will be authorized for sale under the ESPP is equal to the sum of (a) 198,883 shares of common stock and (b) an annual increase on the first day of each year beginning in 2018 and ending in 2027, equal to the lesser of (i) 1% of the shares of common stock outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (ii) such number of shares of common stock as determined by the Company’s board of directors; provided, however, no more than 3.0 million shares of the Company’s common stock may be issued under the ESPP.
Recognized compensation expense			$ 100,000		$ 100,000	$ 100,000	$ 200,000
Number of shares issued from ESPP						26,886		67,508
Non-employee [Member]
Class of Stock [Line Items]
Contractual term						10 years
Number of shares granted to non-employee			0			0
Maximum [Member]
Class of Stock [Line Items]
Fair value of a common stock percentage						110.00%
Maximum [Member] | 2017 Incentive Award Plan [Member]
Class of Stock [Line Items]
Number of authorized shares of common stock under ESPP			12,000,000			12,000,000
Maximum [Member] | 2010 Equity Incentive Plan [Member]
Class of Stock [Line Items]
Stock awards exercisable period						5 years
Maximum [Member] | 2017 Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Number of authorized shares of common stock under ESPP	3,000,000
Minimum [Member]
Class of Stock [Line Items]
Common stock voting rights percentage						10.00%
Minimum [Member] | 2017 Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Employee stock purchase price lower of the closing trading price	85.00%

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Assumptions Used for Grant Date Fair Value (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected stock price volatility, minimum	69.91%	65.40%
Expected stock price volatility, maximum	75.27%	74.21%
Expected dividend yield	0.00%	0.00%
Risk-free interest rate, minimum	2.03%	2.55%
Risk-free interest rate, maximum	2.52%	3.06%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected term (in years)	2 years	5 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected term (in years)	5 years 7 months 6 days	6 years 1 month 6 days

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Outstanding, beginning balance	2,263
Number of Shares, Granted	1,155
Number of Shares, Exercised	0
Number of Shares, Cancelled	(596)
Number of Shares, Outstanding, ending balance	2,822
Number of Shares, Exercisable, ending balance	988
Weighted Average Exercise Price Per Share, Outstanding, beginning balance	$ 12.42
Weighted Average Exercise Price Per Share, Granted	2.18
Weighted Average Exercise Price Per Share, Exercised	0
Weighted Average Exercise Price Per Share, Cancelled	12.82
Weighted Average Exercise Price Per Share, Outstanding, ending balance	8.21
Weighted Average Exercise Price Per Share, Exercisable, ending balance	$ 8.38
Aggregate Intrinsic Value, Outstanding, beginning balance	$ 0
Aggregate Intrinsic Value, Granted	$ 0
Aggregate Intrinsic Value, Exercised	$ 0
Aggregate Intrinsic Value, Cancelled	0
Aggregate Intrinsic Value, Outstanding, ending balance	0
Aggregate Intrinsic Value, Exercisable, ending balance	$ 0

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Nonvested Restricted Stock Units Activity (Detail) - Restricted Stock Units (RSUs) [Member] shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Granted | shares	816
Number of unvested shares, Vested | shares	0
Number of unvested shares, Cancelled | shares	(71)
Ending Balance, Unvested | shares	745
Weighted Average Grant Date Fair Value, Vested | $ / shares	$ 0
Weighted Average Grant Date Fair Value, Granted | $ / shares	2.32
Weighted Average Grant Date Fair Value, Cancelled | $ / shares	2.32
Ending Balance, Unvested | $ / shares	$ 2.32

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Non-cash Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total non-cash stock-based compensation expense	$ 871	$ 995	$ 2,404	$ 1,896
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total non-cash stock-based compensation expense	429	287	843	730
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total non-cash stock-based compensation expense	$ 442	$ 708	$ 1,561	$ 1,166

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Provision for income tax	$ 0	$ 0

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - $ / shares	Aug. 06, 2019	Aug. 01, 2019	Jun. 30, 2019
Weighted Average Exercise Price Per Share, Granted			$ 2.18
Subsequent Event [Member]
Number of Share Options Approved For Repricing		1,854,462
Minimum Exercise Price Per Share, Granted		$ 2.32
Maximum Exercise Price Per Share, Granted		$ 20.53
Weighted Average Exercise Price Per Share, Granted	$ 0.71