Soleno Therapeutics (SLNO) 10-Q 12 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 08, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Registrant Name	SOLENO THERAPEUTICS INC
Entity Central Index Key	0001484565
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock Shares Outstanding		44,710,790
Entity File Number	001-36593
Entity Tax Identification Number	77-0523891
Entity Address, Address Line One	203 Redwood Shores Parkway
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94065
City Area Code	650
City Area Code	213-8444
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SLNO
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 15,070	$ 20,733
Prepaid expenses and other current assets	572	411
Total current assets	15,642	21,144
Long-term assets
Property and equipment, net	19	22
Operating lease right-of-use assets	332	398
Finance lease right-of-use assets	22	24
Intangible assets, net	16,039	16,525
Other long-term assets	59	59
Total assets	32,113	38,172
Current liabilities
Accounts payable	3,480	1,995
Accrued compensation	338	283
Accrued clinical trial site costs	2,846	1,999
Operating lease liabilities	315	305
Other current liabilities	308	382
Total current liabilities	7,287	4,964
Long-term liabilities
Contingent liability for Essentialis purchase price	6,522	5,938
Other long-term liabilities	60	147
Total liabilities	22,632	23,225
Commitments and contingencies (Note 6)
Stockholders’ equity
Common stock	45	45
Additional paid-in-capital	173,100	172,708
Accumulated deficit	(163,664)	(157,806)
Total stockholders’ equity	9,481	14,947
Total liabilities and stockholders’ equity	32,113	38,172
2017 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	7,656	10,822
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 1,107	$ 1,354

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	44,686,811	44,658,054
Common stock, shares outstanding	44,686,811	44,658,054

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses
Research and development	$ 6,695	$ 2,760
General and administrative	2,003	2,012
Change in fair value of contingent consideration	584	206
Total operating expenses	9,282	4,978
Operating loss	(9,282)	(4,978)
Other income (expense)
Change in fair value of warrants liabilities	3,413	(1,919)
Loss from minority interest investment		(190)
Interest income	11	57
Total other income (expense)	3,424	(2,052)
Net loss	$ (5,858)	$ (7,030)
Net loss per common share, basic and diluted	$ (0.13)	$ (0.22)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	44,679,858	31,756,120

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balances at beginning at Dec. 31, 2018	$ 30,413	$ 32	$ 157,413	$ (127,032)
Balances at beginning (shares) at Dec. 31, 2018		31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	202		202
Issuance of restricted stock units under equity incentive plans	46		46
Issuance of restricted stock units under equity incentive plans (shares)		21,415
Net loss	(7,030)			(7,030)
Balances at ending at Mar. 31, 2019	23,631	$ 32	157,661	(134,062)
Balances at end (shares) at Mar. 31, 2019		31,776,584
Balances at beginning at Dec. 31, 2019	14,947	$ 45	172,708	(157,806)
Balances at beginning (shares) at Dec. 31, 2019		44,658,054
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	296		296
Issuance of restricted stock units under equity incentive plans	96		96
Issuance of restricted stock units under equity incentive plans (shares)		28,757
Net loss	(5,858)			(5,858)
Balances at ending at Mar. 31, 2020	$ 9,481	$ 45	$ 173,100	$ (163,664)
Balances at end (shares) at Mar. 31, 2020		44,686,811

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (5,858)	$ (7,030)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	489	489
Noncash lease expense	68	110
Stock-based compensation expense	392	248
Change in fair value of stock warrants	(3,413)	1,919
Change in fair value of contingent consideration	584	206
Operating loss on minority interest investment		190
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(161)	(74)
Due from related party		(8)
Accounts payable	1,485	324
Accrued compensation	55	(92)
Accrued clinical trial site costs	847	188
Operating lease liabilities	10	(117)
Other liabilities	(157)	(40)
Net cash used in operating activities	(5,659)	(3,687)
Cash flows from investing activities:
Purchases of property and equipment		(10)
Net cash used in investing activities		(10)
Cash flows from financing activities:
Principal paid on finance lease liabilities	(4)
Net cash used in financing activities	(4)
Net decrease in cash and cash equivalents	(5,663)	(3,697)
Cash and cash equivalents, beginning of period	20,733	23,099
Cash and cash equivalents, end of period	$ 15,070	$ 19,402

Overview

Overview	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Overview	Note 1. Overview Soleno Therapeutics, Inc. (the “Company” or “Soleno”) was incorporated in the State of Delaware on August 25, 1999, and is located in Redwood City, California. The Company initially established its operations as Capnia, a diversified healthcare company that developed and commercialized innovative diagnostics, devices and therapeutics addressing unmet medical needs. During 2017, Soleno received stockholder approval to amend its Amended and Restated Certificate of Incorporation to change its name from “Capnia, Inc.” to “Soleno Therapeutics, Inc.” and merged with Essentialis, Inc. The Company’s Diazoxide Choline Controlled Release tablets, or DCCR Prader-Willi Syndrome, or PWS

Going Concern and Management's

Going Concern and Management's Plans	3 Months Ended
	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Going Concern and Management's Plans	Note 2. Going Concern and Management’s Plans The Company had a net loss of $5.9 million during the three months ended March 31, 2020 and has an accumulated deficit of $163.7 million at March 31, 2020 resulting from having incurred losses since its inception. The Company had $15.1 The accompanying condensed consolidated financial statements have been prepared under the assumption the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The condensed consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern. The Company expects to continue incurring losses for the foreseeable future and will be required to raise additional capital to complete its clinical trials, pursue product development initiatives and penetrate markets for the sale of its products. Management believes that the Company will continue to have access to capital resources through possible public or private equity offerings, debt financings, corporate collaborations or other means, but the Company’s access to such capital resources is uncertain and is not assured. If the Company is unable to secure additional capital, it may be required to curtail its clinical trials and development of new products and take additional measures to reduce expenses in order to conserve its cash in amounts sufficient to sustain operations and meet its obligations. These measures could cause significant delays in the Company’s efforts to complete its clinical trials and commercialize its products, which is critical to the realization of its business plan and the future operations of the Company. The condensed consolidated financial statements do not include any adjustments relating to the recoverability and classification of asset amounts or the classification of liabilities that might be necessary should it be unable to continue as a going concern. Management believes that the Company does not have sufficient capital resources to sustain operations through at least the next twelve months from the date of this filing. Additionally, in view of the Company’s expectation to incur significant losses for the foreseeable future it will be required to raise additional capital resources in order to fund its operations, although the availability of, and the Company’s access to such resources is not assured. Accordingly, management believes that there is substantial doubt regarding the Company’s ability to continue operating as a going concern within one year from the date of filing these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 3. Summary of Significant Accounting Policies There have been no material changes to the significant accounting policies during the three months ended March 31, 2020 as compared to the significant accounting policies described in Note 3 of the “Notes to Consolidated Financial Statements” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Below are those policies with current period updates. Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared on a going concern basis in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three months ended March 31, 2020, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2020. For further information, refer to the financial statements and footnotes included in the Company’s annual financial statements for the fiscal year ended December 31, 2019, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 4, 2020. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and reported amounts of expenses in the financial statements and accompanying notes. Actual results could differ from those estimates. Key estimates included in the financial statements include the valuation of deferred income tax assets, the valuation of financial instruments, stock-based compensation, value and life of acquired intangibles, and the valuation of contingent liabilities. The contingent liability represents the fair value of the contingent consideration arising from the Company’s acquisition of Essentialis in 2017. As part of the purchase price, the Company is obligated to make cash earn out payments to Essentialis stockholders up to a maximum of $30 million upon the achievement of certain commercial milestones. Recent Accounting Standards From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Recently Adopted Accounting Standards In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. Recently Issued Accounting Standards In December 2019, the FASB issued ASU 2019-12: “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” During the three months ended March 31, 2020, other than ASU 2019-12, there have been no new, or existing recently issued, accounting pronouncements that are of significance, or potential significance, that impact the Company’s condensed consolidated interim financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Note 4. Fair Value of Financial Instruments The carrying value of the Company’s cash, cash equivalents and accounts payable, approximate fair value due to the short-term nature of these items. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: • Level I — • Level II — • Level III — The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands). Fair Value Measurements at March 31, 2020 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 7,656 $ — $ — $ 7,656 2018 PIPE warrant liability 1,107 — — 1,107 Essentialis purchase price contingency liability 6,522 — — 6,522 Total common stock warrant and contingent consideration liability $ 15,285 $ — $ — $ 15,285 Fair Value Measurements at December 31, 2019 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 10,822 $ — $ — $ 10,822 2018 PIPE warrant liability 1,354 — — 1,354 Essentialis purchase price contingency liability 5,938 — — 5,938 Total common stock warrant and contingent consideration liability $ 18,114 $ — $ — $ 18,114 The Company’s estimated fair value of the 2017 PIPE Warrants and the 2018 PIPE Warrants was calculated using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation-pricing model requires the input of highly subjective assumptions including the expected stock price volatility, the expected term, the expected dividend yield and the risk-free interest rate. The fair value of the Essentialis purchase price contingent liability is estimated using scenario-based methods based upon the Company’s analysis of the likelihood of obtaining specified approvals from the Federal Drug Administration as well as reaching cumulative revenue milestones. During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at fair value using Level 3 inputs. There were no transfers between levels within the hierarchy during the periods presented. The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 liabilities (dollars in thousands). Series C Warrants 2017 PIPE Warrants 2018 PIPE Warrants Purchase Price Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Contingent Liability Balance at December 31, 2019 118,083 $ — 6,024,425 $ 10,822 513,617 $ 1,354 $ 5,938 Expiration of Series C Warrants (118,083 ) — — — — — — Change in value of 2017 PIPE Warrants — — — (3,166 ) — — — Change in value of 2018 PIPE Warrants — — — — — (247 ) — Change in value of contingent liability — — — — — — 584 Balance at March 31, 2020 — $ — 6,024,425 $ 7,656 513,617 $ 1,107 $ 6,522

Warrant Liabilities

Warrant Liabilities	3 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Warrant Liabilities	Note 5. Warrant Liabilities The Company has issued multiple warrant series, of which the 2017 PIPE Warrants and the 2018 PIPE Warrants (the “Warrants”) remain outstanding at March 31, 2020 and are considered liabilities pursuant to the guidance established by ASC 815 Derivatives and Hedging. Accounting Treatment The Company accounts for the Warrants in accordance with the guidance in ASC 815 Series C Warrants As of March 31, 2020, the fair value of the Series C Warrants was zero as the warrants had expired. This balance is consistent with the balance as of December 31, 2019. The Company calculated the fair value of the Series C Warrants as of December 31, 2019 using a Black-Scholes pricing model. The Black-Scholes pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The Company used the following inputs. December 31, 2019 Volatility 90 % Contractual term (years) 0.17 Expected dividend yield — % Risk-free rate 1.52 % Warrants Issued as Part of the Units in the 2017 PIPE Offering The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holder of each of the 8,141,116 units to purchase 0.74 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS. The exercise price and number of shares of common stock issuable upon exercise of the 2017 PIPE Warrants may be adjusted in certain circumstances, including the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2017 PIPE Warrants will not be reduced below $1.72. In the event of a change of control of the Company, the holders of unexercised warrants may present their unexercised warrants to the Company, or its successor, to be purchased by the Company, or its successor, in an amount equal to the per share value determined by the Black Scholes methodology. As of March 31, 2020, the fair value of the 2017 PIPE Warrants was estimated at $ 7.7 3.2 The Company has calculated the fair value of the 2017 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values. March 31, 2020 December 31, 2019 Volatility 105 % 99 % Contractual term (years) 0.7 1.0 Expected dividend yield — % — % Risk-free rate 0.10 % 1.60 % Warrants Issued as Part of the Units in the 2018 PIPE Offering The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders of each of the 10,272,375 units to purchase 0.05 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023. The exercise price and number of shares of common stock issuable upon exercise of the 2018 PIPE Warrants may be adjusted in certain circumstances, including the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2018 PIPE Warrants will not be reduced below $2.00. In the event of a change of control of the Company, the holders of unexercised warrants may present their unexercised warrants to the Company, or its successor, to be purchased by the Company, or its successor, in an amount equal to the per share value determined by the Black Scholes methodology. As of March 31, 2020, the fair value of the 2018 PIPE Warrants was estimated at $ 1.1 247,000 The Company has calculated the fair value of the 2018 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values. March 31, 2020 December 31, 2019 Volatility 105 % 99 % Contractual term (years) 3.7 4.0 Expected dividend yield — % — % Risk-free rate 0.33 % 1.56 % The Monte Carlo simulation of a geometric Brownian motion model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates. • Volatility: The Company calculates the estimated volatility rate based on the volatilities of common stock of comparable companies in its industry. • Contractual term: The expected life of the warrants, which is based on the contractual term of the warrants. • Expected dividend yield: The Company has never declared or paid any cash dividends and does not currently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero. • Risk-free rate: The risk-free interest rate is based on the U.S. Treasury rate for similar periods as those of expected volatility.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 6. Commitments and Contingencies Facility Leases The Company’s previous operating lease for its headquarters facility office space in Redwood City, California, terminated in August 2019, along with the related subleases. One of the subleases was with Capnia, of which the Company was a joint owner until September 2019. Sublease income received from Capnia during the three months ended March 31, 2019 was approximately $25,000. In July 2019, the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021. The lease also provides the Company with the right to use office furniture in the space and allows the purchase of this furniture at the end of the lease term for $1. The lease agreement requires monthly lease payments of approximately $29,000 beginning in November of 2019, with an increase to approximately $30,000 per month in September of 2020. The Company has accounted for the new lease as an operating lease for the office space and a finance lease for the office furniture, based on their relative standalone prices. The components of lease expense during the three months ended March 31, 2019 and 2018 were as follows (in thousands): Three Months Ended March 31, 2020 2019 Operating lease cost: Operating lease cost $ 76 $ 119 Sublease income — (65 ) Total operating lease cost $ 76 $ 54 Finance lease cost: Amortization of right-of-use assets $ 2 $ — Interest on lease liabilities 1 — Total finance lease cost $ 3 $ — Contingencies In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated.

CoSense Joint Venture Agreement

CoSense Joint Venture Agreement and Discontinued Operations	3 Months Ended
	Mar. 31, 2020
Discontinued Operations And Disposal Groups [Abstract]
CoSense Joint Venture Agreement and Discontinued Operations	Note 7. CoSense Joint Venture Agreement and Discontinued Operations In December 2017, the Company entered into a joint venture with OptAsia Healthcare Limited CoSense was Soleno’s first Sensalyze Technology Platform product to receive 510(k) clearances from the FDA and CE Mark certification. During October 2018, the Company and OAHL determined and agreed that the cumulative investment made by OAHL exceeded $1.2 million during the quarter ended September 30, 2018. Accordingly, on October 16, 2018, Capnia issued 1,690,322 shares of its common stock to OAHL, representing 53% of its outstanding shares. After the share issuance the Company no longer held a controlling interest in Capnia and resulted in the deconsolidation of Capnia’s financial statements from those of the Company. The remaining 47% investment in Capnia was classified as an equity method investment and was presented as a Minority interest investment in former subsidiary in the condensed consolidated balance sheet. The Company’s share of Capnia’s net losses during the three months ended March 31, 2019 are recorded in the condensed consolidated statements of operations in the line titled “Loss from minority interest investment”. During September 2019, the Company sold its remaining 47% investment in Capnia. Following the transaction, the Company has no interest remaining in Capnia and the previous joint venture agreement with OAHL has been terminated.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Stockholders' Equity	Note 8. Stockholders’ Equity Equity Incentive Plans The Company has adopted the 2014 Equity Incentive Plan, or the Plan. Under the Plan the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units, performance units or performance shares to employees, directors, advisors, and consultants. Options granted under the Plan may be incentive stock options (“ISOs”) or nonqualified stock options (“NSOs”). ISOs may be granted only to Company employees, including officers and directors. The Board of Directors has the authority to determine to whom stock options will be granted, the number of options, the term, and the exercise price. Options are to be granted at an exercise price not less than fair value. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price of an option will not be less than 110% of fair value. The vesting period is normally monthly over a period of 4 years from the vesting date. The contractual term of an option is no longer than five years for ISOs for which the grantee owns greater than 10% of the voting power of all classes of stock and no longer than ten years for all other options. The terms and conditions governing restricted stock units is at the sole discretion of the Board. As of March 31, 2020, a total of 190,601 shares are available for future grant under the Plan. The Company recognizes stock-based compensation expense related to options and restricted stock units granted to employees, directors and consultants. The compensation expense is allocated on a departmental basis, based on the classification of the award holder. No income tax benefits have been recognized in the statements of operations for stock-based compensation arrangements during any of the periods presented. Stock-based compensation expense was recognized in the condensed consolidated statements of operations as follows (in thousands). Three Months Ended March 31, 2020 2019 Research and development $ 99 $ 41 General and administrative 293 207 Total $ 392 $ 248 Stock Options The Company granted options to purchase 464,000 of the Company’s common stock during the three months ended March 31, 2019 Expected life (years) 6.0-6.1 Risk-free interest rate 2.6% Volatility 71% Dividend rate — % The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates: • Expected life: The expected life of stock options represents the average of the contractual term of the options and the weighted-average vesting period, as permitted under the simplified method. The Company does not believe it is able to rely on historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term for use in estimating the fair value-based measurement of stock options. Therefore, it has opted to use the “simplified method” for estimating the expected term of options. • Risk-free interest rate: The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to liquidity. • Volatility: The estimated volatility rate based on the volatilities of common stock of comparable companies in the Company’s industry. • Dividend rate: The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero. The following table summarizes stock option transactions for the three months ended March 31, 2020 as issued under the 2014 Plan: Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term Outstanding Share (in years) Balance at December 31, 2019 2,123,117 $ 4.62 7.87 Options canceled/forfeited (38,359 ) $ 2.11 Balance at March 31, 2020 2,084,758 $ 4.66 7.59 Options vested at March 31, 2020 1,220,423 $ 6.65 7.01 Options vested and expected to vest at March 31, 2020 2,084,758 $ 4.66 7.59 The weighted-average grant date fair value of options granted was and $1.08 per share for the three months ended March 31, 2019. At March 31, 2020 total unrecognized employee stock-based compensation related to stock options was approximately $919,000, which is expected to be recognized over the weighted-average remaining vesting period of 2.2 years. As of March 31, 2020, the outstanding stock options had an intrinsic value of approximately $883,000. Restricted Stock Units There were 687,257 and 21,415 restricted stock units granted by the Company during the three months ended March 31, 2020 and March 31, 2019, respectively, to employees and directors. The shares granted to directors were 100% vested on the grant date and represent compensation for past board services. The shares granted to employees typically vest annually over a period of four years. The shares were valued based on the Company’s common stock price on the grant date. The following table summarizes restricted stock unit transactions for the three months ended March 31, 2020 as issued under the Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at December 31, 2019 - Restricted stock units granted 687,257 $ 3.83 Restricted stock units vested (28,757 ) $ 3.35 Outstanding at March 31, 2020 658,500 $ 3.85 The weighted-average grant-date fair value of all restricted stock units granted during the three months ended March 31, 2020 and March 31, 2019 was $3.83 and $2.18, respectively. The fair value of all restricted stock units vested during the three months ended March 31, 2020 and March 31, 2019 was approximately $96,000 and approximately $46,000, respectively. At March 31, 2020 total unrecognized employee stock-based compensation related to restricted stock units was $2.4 million, which is expected to be recognized over the weighted-average remaining vesting period of 3.7 years. 2014 Employee Stock Purchase Plan The Company’s board of directors and stockholders have adopted the 2014 Employee Stock Purchase Plan, or the ESPP. The ESPP has become effective, and the board of directors will implement commencement of offers thereunder in its discretion. A total of 27,967 shares of the Company’s common stock has been made available for sale under the ESPP. In addition, the ESPP provides for annual increases in the number of shares available for issuance under the plan on the first day of each year beginning in the year following the initial date that the board of directors authorizes commencement, equal to the least of: • 1.0% of the outstanding shares of the Company’s common stock on the first day of such year; • 55,936 shares; or • such amount as determined by the board of directors. As of March 31, 2020, there were no purchases by employees under this plan. Series D Warrants The Company issued 270,270 Series D Warrants in October 2015, which are exercisable into 540,540 shares of the Company’s common stock, with an exercise price of $8.75 and a term of five years expiring on October 15, 2020. The Company’s Series D Warrants contain standard anti-dilution provisions for stock dividends, stock splits, subdivisions, combinations and similar types of recapitalization events. They also contain a cashless exercise feature that provides for their net share settlement at the option of the holder in the event that there is no effective registration statement covering the continuous offer and sale of the warrants and underlying shares. The Company is required to comply with certain requirements to cause or maintain the effectiveness of a registration statement for the offer and sale of these securities. The Series D Warrant agreement further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate VWAP of the shares into which each Series D Warrant is convertible in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of this securities agreement and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds to the registration payment arrangement. The Series D Warrant agreement specifically provides that under no circumstances will the Company be required to settle any Series D Warrant exercise for cash, whether by net settlement or otherwise. Accounting Treatment The Company accounts for the Series D Warrants in accordance with the guidance in ASC 815 Derivatives and Hedging. Other Common Stock Warrants As of March 31, 2020, the Company had 102,070 common stock warrants outstanding from the 2010/2012 convertible notes, with an exercise price of $24.35 and a term of 10 years expiring in November 2024. The Company also had 16,500 common stock warrants issued to the underwriter in the Company’s IPO, with an exercise price of $35.70 and a term of 10 years, expiring in November 2024.

Net loss per share

Net loss per share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net loss per share	Note 9. Net loss per share Basic net loss per share is computed by dividing net loss by the weighted-average number of common stock actually outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common stock outstanding and dilutive potential common stock that would be issued upon the exercise of common stock warrants and options. For the three months ended March 31, 2020 and 2019, the effect of issuing the potential common stock is anti-dilutive due to the net losses in those periods and the number of shares used to compute basic and diluted earnings per share are the same in each of those periods. The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of March 31, 2020 2019 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 2,084,758 2,116,107 Outstanding restricted stock units 658,500 — Warrants issued to underwriter to purchase common stock 16,500 16,500 Series A warrants to purchase common stock — 485,121 Series C warrants to purchase common stock — 118,083 Series D warrants to purchase common stock 540,540 540,540 2017 PIPE warrants 6,024,425 6,024,425 2018 PIPE warrants 513,617 513,617 Total 9,940,410 9,916,463

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 10. Subsequent Events The Company has evaluated its subsequent events from March 31, 2020 through the date these condensed consolidated financial statements were issued and has determined that there are no subsequent events requiring disclosure in these condensed consolidated financial statements other than the item noted below. PPP Term Note On April 22, 2020, the Company entered into a $350,000 loan with Silicon Valley Bank (“SVB”) pursuant to the Small Business Administration’s (“SBA”) Paycheck Protection Program ("the PPP"). The loan proceeds were intended to be used for payroll, rent and utilities over the eight- week period following the date of the loan. At the time the Company applied for the PPP loan, it believed in good faith that it met all of the certification requirements for a PPP loan. However, on April 23, 2020, the SBA issued additional guidance with respect to PPP loans. The Company evaluated this new guidance and concluded that currently it may not be able to meet all of the certification requirements. As such, the Company decided to return all of the funds received under the PPP loan (including interest accrued on such funds) to the SBA and on May 6, 2020 the Company instructed SVB to make repayment.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared on a going concern basis in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three months ended March 31, 2020, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2020. For further information, refer to the financial statements and footnotes included in the Company’s annual financial statements for the fiscal year ended December 31, 2019, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 4, 2020.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and reported amounts of expenses in the financial statements and accompanying notes. Actual results could differ from those estimates. Key estimates included in the financial statements include the valuation of deferred income tax assets, the valuation of financial instruments, stock-based compensation, value and life of acquired intangibles, and the valuation of contingent liabilities. The contingent liability represents the fair value of the contingent consideration arising from the Company’s acquisition of Essentialis in 2017. As part of the purchase price, the Company is obligated to make cash earn out payments to Essentialis stockholders up to a maximum of $30 million upon the achievement of certain commercial milestones.
Recent Accounting Standards	Recent Accounting Standards From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Recently Adopted Accounting Standards In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. Recently Issued Accounting Standards In December 2019, the FASB issued ASU 2019-12: “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” During the three months ended March 31, 2020, other than ASU 2019-12, there have been no new, or existing recently issued, accounting pronouncements that are of significance, or potential significance, that impact the Company’s condensed consolidated interim financial statements.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Measured at Fair Value on Recurring Basis	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands). Fair Value Measurements at March 31, 2020 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 7,656 $ — $ — $ 7,656 2018 PIPE warrant liability 1,107 — — 1,107 Essentialis purchase price contingency liability 6,522 — — 6,522 Total common stock warrant and contingent consideration liability $ 15,285 $ — $ — $ 15,285 Fair Value Measurements at December 31, 2019 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 10,822 $ — $ — $ 10,822 2018 PIPE warrant liability 1,354 — — 1,354 Essentialis purchase price contingency liability 5,938 — — 5,938 Total common stock warrant and contingent consideration liability $ 18,114 $ — $ — $ 18,114
Summary of Changes in Fair Value of Level 3 Financial Instruments	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 liabilities (dollars in thousands). Series C Warrants 2017 PIPE Warrants 2018 PIPE Warrants Purchase Price Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Contingent Liability Balance at December 31, 2019 118,083 $ — 6,024,425 $ 10,822 513,617 $ 1,354 $ 5,938 Expiration of Series C Warrants (118,083 ) — — — — — — Change in value of 2017 PIPE Warrants — — — (3,166 ) — — — Change in value of 2018 PIPE Warrants — — — — — (247 ) — Change in value of contingent liability — — — — — — 584 Balance at March 31, 2020 — $ — 6,024,425 $ 7,656 513,617 $ 1,107 $ 6,522

Warrant Liabilities (Tables)

Warrant Liabilities (Tables)	3 Months Ended
	Mar. 31, 2020
Series C Warrant [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The Company used the following inputs. December 31, 2019 Volatility 90 % Contractual term (years) 0.17 Expected dividend yield — % Risk-free rate 1.52 %
2017 PIPE Warrant Liability [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The following summarizes certain key assumptions used in estimating the fair values. March 31, 2020 December 31, 2019 Volatility 105 % 99 % Contractual term (years) 0.7 1.0 Expected dividend yield — % — % Risk-free rate 0.10 % 1.60 %
2018 PIPE Warrant Liability [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The following summarizes certain key assumptions used in estimating the fair values. March 31, 2020 December 31, 2019 Volatility 105 % 99 % Contractual term (years) 3.7 4.0 Expected dividend yield — % — % Risk-free rate 0.33 % 1.56 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Components of Lease Expense	The components of lease expense during the three months ended March 31, 2019 and 2018 were as follows (in thousands): Three Months Ended March 31, 2020 2019 Operating lease cost: Operating lease cost $ 76 $ 119 Sublease income — (65 ) Total operating lease cost $ 76 $ 54 Finance lease cost: Amortization of right-of-use assets $ 2 $ — Interest on lease liabilities 1 — Total finance lease cost $ 3 $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Summary of Stock Based Compensation Expense	Stock-based compensation expense was recognized in the condensed consolidated statements of operations as follows (in thousands). Three Months Ended March 31, 2020 2019 Research and development $ 99 $ 41 General and administrative 293 207 Total $ 392 $ 248
Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model	The fair value of each award granted during the three months ended March 31, 2019 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions Expected life (years) 6.0-6.1 Risk-free interest rate 2.6% Volatility 71% Dividend rate — %
Summary of Stock Option Transactions	The following table summarizes stock option transactions for the three months ended March 31, 2020 as issued under the 2014 Plan: Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term Outstanding Share (in years) Balance at December 31, 2019 2,123,117 $ 4.62 7.87 Options canceled/forfeited (38,359 ) $ 2.11 Balance at March 31, 2020 2,084,758 $ 4.66 7.59 Options vested at March 31, 2020 1,220,423 $ 6.65 7.01 Options vested and expected to vest at March 31, 2020 2,084,758 $ 4.66 7.59
Summary of Restricted Stock Unit Transactions	The following table summarizes restricted stock unit transactions for the three months ended March 31, 2020 as issued under the Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at December 31, 2019 - Restricted stock units granted 687,257 $ 3.83 Restricted stock units vested (28,757 ) $ 3.35 Outstanding at March 31, 2020 658,500 $ 3.85

Net loss per share (Tables)

Net loss per share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding	The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of March 31, 2020 2019 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 2,084,758 2,116,107 Outstanding restricted stock units 658,500 — Warrants issued to underwriter to purchase common stock 16,500 16,500 Series A warrants to purchase common stock — 485,121 Series C warrants to purchase common stock — 118,083 Series D warrants to purchase common stock 540,540 540,540 2017 PIPE warrants 6,024,425 6,024,425 2018 PIPE warrants 513,617 513,617 Total 9,940,410 9,916,463

Going Concern and Management'_2

Going Concern and Management's Plans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Net loss	$ (5,858)	$ (7,030)
Accumulated deficit	(163,664)		$ (157,806)
Cash on hand	15,100
Net cash used in operating activities	$ (5,659)	$ (3,687)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	Mar. 31, 2020USD ($)
Essentialis, Inc. [Member] | Earnout Payments [Member]
Schedule Of Significant Accounting Policies [Line Items]
Maximum potential cash earnout payments	$ 30,000,000

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Liabilities
Contingent liability for Essentialis purchase price	$ 6,522	$ 5,938
2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	7,656	10,822
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,107	1,354
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	15,285	18,114
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	7,656	10,822
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,107	1,354
Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	6,522	5,938
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	15,285	18,114
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	7,656	10,822
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,107	1,354
Level 3 [Member] | Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 6,522	$ 5,938

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 3 Financial Instruments (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)shares
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 5,938
Change in value of liabilities	584
Balance at end of period	$ 6,522
Series C Warrant [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares | shares	118,083
Expiration of warrants, in shares | shares	(118,083)
2017 PIPE Warrant Liability [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 10,822
Balance at the beginning of period, in shares | shares	6,024,425
Change in value of liabilities	$ (3,166)
Balance at end of period	$ 7,656
Balance at the end of period, in shares | shares	6,024,425
2018 PIPE Warrant Liability [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 1,354
Balance at the beginning of period, in shares | shares	513,617
Change in value of liabilities	$ (247)
Balance at end of period	$ 1,107
Balance at the end of period, in shares | shares	513,617

Warrant Liabilities - Additiona

Warrant Liabilities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020USD ($)$ / shares	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 19, 2018$ / sharesshares	Dec. 15, 2017$ / sharesshares
Class Of Warrant Or Right [Line Items]
Change in fair value of stock warrants	$ (3,413,000)	$ 1,919,000
Expected Dividend Yield [Member]
Class Of Warrant Or Right [Line Items]
Measurement input	0
Series C Warrant [Member]
Class Of Warrant Or Right [Line Items]
Warrant liability	$ 0
2017 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Warrant liability	$ 7,656,000		$ 10,822,000
Number of common stock purchased upon issuance of warrants | shares					8,141,116
Warrant to call common stock | shares					0.74
Exercise price of warrants exercised | $ / shares					$ 2
Warrant issuance description	The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holder of each of the 8,141,116 units to purchase 0.74 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS.
Change in fair value of stock warrants	$ (3,200,000)
Fair value of estimated warrants	$ 7,700,000
2017 PIPE Warrant Liability to Purchase Common Stock [Member] | Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised | $ / shares	$ 1.72
2018 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Warrant liability	$ 1,107,000		$ 1,354,000
Number of common stock purchased upon issuance of warrants | shares				10,272,375
Warrant to call common stock | shares				0.05
Exercise price of warrants exercised | $ / shares				$ 2
Warrant issuance description	The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders of each of the 10,272,375 units to purchase 0.05 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023.
Change in fair value of stock warrants	$ (247,000)
Fair value of estimated warrants	$ 1,100,000
2018 PIPE Warrant Liability [Member] | Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised | $ / shares	$ 2

Warrant Liabilities - Fair Valu

Warrant Liabilities - Fair Value of Convertible Preferred Stock Warrant Liability (Detail)	Mar. 31, 2020	Dec. 31, 2019
Expected Dividend Yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0
Series C Warrant [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		0.90
Series C Warrant [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term		2 months 1 day
Series C Warrant [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input		0.0152
2017 PIPE Warrant Liability [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.05	0.99
2017 PIPE Warrant Liability [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	8 months 12 days	1 year
2017 PIPE Warrant Liability [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0010	0.0160
2018 PIPE Warrant Liability [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.05	0.99
2018 PIPE Warrant Liability [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	3 years 8 months 12 days	4 years
2018 PIPE Warrant Liability [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0033	0.0156

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended			3 Months Ended
	Sep. 30, 2020USD ($)	Nov. 30, 2019USD ($)	Jul. 31, 2019USD ($)ft²	Mar. 31, 2020	Mar. 31, 2019USD ($)
Commitments and Contingencies [Line Items]
Sublease income					$ 65,000
Redwood City, California [Member]
Commitments and Contingencies [Line Items]
Area of operating lease | ft²			6,368
Operating lease, description				the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021
Operating lease beginning date			2019-09
Operating lease, expiration			2021-05
Payment to acquire office furniture under operating lease			$ 1
Future minimum commitment under non-cancelable operating lease		$ 29,000
Redwood City, California [Member] | Forecast [Member]
Commitments and Contingencies [Line Items]
Future minimum commitment under non-cancelable operating lease	$ 30,000
Capnia Inc Joint Venture [Member] | Redwood City, California [Member]
Commitments and Contingencies [Line Items]
Sublease income					$ 25,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 76	$ 119
Sublease income		(65)
Total operating lease cost	76	$ 54
Amortization of right-of-use assets	2
Interest on lease liabilities	1
Total finance lease cost	$ 3

CoSense Joint Venture Agreeme_2

CoSense Joint Venture Agreement and Discontinued Operations - Additional Information (Detail) - Capnia Inc Joint Venture [Member] - USD ($) $ / shares in Units, $ in Thousands	Oct. 16, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership interest		47.00%	47.00%
OAHL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Remaining interest		$ 0
OAHL [Member] | Corporate Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment threshold requirement				$ 2,200
Negotiated price per share				$ 1
Investment threshold requirement stock issuance			$ 1,200	$ 1,200
Issuance of common stock (shares)	1,690,322
Percentage of ownership interest	53.00%

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Oct. 31, 2015	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield		0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)			$ 1.08
Stock options outstanding, intrinsic value		$ 883,000
Number of shares available for issuance under the plan on the first day of each year		44,686,811		44,658,054
Series D Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	270,270
Number of common stock purchased upon issuance of warrants	540,540
Exercise price of warrants (in dollars per share)	$ 8.75
Warrants term	5 years
Warrants expiration date	Oct. 15, 2020
Liquidated damages amount percent of VWAP (percent)	1.00%
Warrants to Purchase Stock [Member] | 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)		102,070
Exercise price of warrants (in dollars per share)		$ 24.35
Warrants term		10 years
Warrants expiration period		2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)		16,500
Exercise price of warrants (in dollars per share)		$ 35.70
Warrants term		10 years
Warrants expiration period		2024-11
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant		27,967
Percentage of outstanding stock maximum		1.00%
Number of shares available for issuance under the plan on the first day of each year		55,936
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership interest of voting rights of all classes of stock (percent)		10.00%
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		4 years
Number of shares available for grant		190,601
Income tax benefits recognized from stock-based compensation		$ 0	$ 0
Number of options granted		0	464,000
Future stock-based compensation for unvested employee options granted and outstanding		$ 919,000
Future stock-based compensation, requisite service period		2 years 2 months 12 days
Stock Options [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value		110.00%
Stock Options [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option		10 years
ISOs [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option		5 years
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		4 years
Future stock-based compensation for unvested employee options granted and outstanding		$ 2,400,000
Stock units granted		687,257	21,415
Vesting percentage		100.00%
Weighted average grant-date fair value of all restricted stock units granted		$ 3.83	$ 2.18
Fair value of restricted stock units vested		$ 96,000	$ 46,000
Weighted average remaining vesting period		3 years 8 months 12 days

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - Continuing Operations [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 392	$ 248
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	99	41
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 293	$ 207

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate		2.60%
Volatility		71.00%
Dividend rate	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)		6 years
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)		6 years 1 month 6 days

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Transactions (Detail) - Stock Options [Member] - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	2,123,117
Options canceled/forfeited	(38,359)
Ending balance	2,084,758	2,123,117
Options vested at end of period (shares)	1,220,423
Options vested and expected to vest at end of period (shares)	2,084,758
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 4.62
Options canceled/forfeited (in dollars per share)	2.11
Ending balance (in dollars per share)	4.66	$ 4.62
Options vested at end of period (in dollars per share)	6.65
Options vested and expected to vest at end of period (in dollars per share)	$ 4.66
Weighted Average Remaining Contractual Term
Options outstanding at end of period	7 years 7 months 2 days	7 years 10 months 13 days
Options vested at end of period	7 years 3 days
Options vested and expected to vest at end of period	7 years 7 months 2 days

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Restricted Stock Unit Transactions (Detail) - Restricted Stock Units [Member] - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock units granted	687,257	21,415
Restricted stock units vested	(28,757)
Ending balance	658,500
Weighted-average grant date fair value
Restricted stock units granted (in dollars per share)	$ 3.83	$ 2.18
Restricted stock units vested (in dollars per share)	3.35
Ending balance (in dollars per share)	$ 3.85

Net loss per share - Schedule o

Net loss per share - Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding (Detail) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	9,940,410	9,916,463
Warrants Issued to 2010/2012 Convertible Note Holders to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	102,070	102,070
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	2,084,758	2,116,107
Outstanding Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	658,500
Warrants Issued to Underwriter to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	16,500	16,500
Series A Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding		485,121
Series C Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding		118,083
Series D Warrants To Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	540,540	540,540
2017 PIPE Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	6,024,425	6,024,425
2018 PIPE Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	513,617	513,617

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	Apr. 22, 2020USD ($)
Silicon Valley Bank | Subsequent Event | PPP Term Note
Subsequent Event [Line Items]
Principal amount	$ 350,000