Soleno Therapeutics (SLNO) 10-Q 10 May 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 05, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
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		120,088,816
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
Local Phone Number	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, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 28,974	$ 21,304
Prepaid expenses and other current assets	1,004	1,118
Total current assets	29,978	22,422
Long-term assets
Property and equipment, net	27	33
Operating lease right-of-use assets	350	421
Intangible assets, net	12,151	12,637
Other long-term assets	40	40
Total assets	42,546	35,553
Current liabilities
Accounts payable	2,411	3,254
Accrued compensation	598	728
Accrued clinical trial site costs	3,521	3,420
Operating lease liabilities	344	282
Other current liabilities	439	323
Total current liabilities	7,313	8,007
Long-term liabilities
Contingent liability for Essentialis purchase price	8,689	9,547
Long-term lease liabilities	79	175
Total liabilities	16,085	17,760
Commitments and contingencies (Note 6)
Stockholders’ equity
Common stock, $0.001 par value, 250,000,000 shares authorized, 120,088,816 and 79,864,310 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively.	120	80
Additional paid-in-capital	245,422	231,068
Accumulated deficit	(219,079)	(213,355)
Accumulated other comprehensive loss	(2)
Total stockholders’ equity	26,461	17,793
Total liabilities and stockholders’ equity	42,546	35,553
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 4	$ 31

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	120,088,816	79,864,310
Common stock, shares outstanding	120,088,816	79,864,310

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses
Research and development	$ 3,988	$ 7,164
General and administrative	2,643	2,979
Change in fair value of contingent consideration	(858)	(987)
Total operating expenses	5,773	9,156
Operating loss	(5,773)	(9,156)
Other income
Change in fair value of warrants liabilities	27	201
Interest income	22	1
Total other income	49	202
Net loss	(5,724)	(8,954)
Other comprehensive loss
Foreign currency translation adjustment	(2)
Total comprehensive loss	$ (5,726)	$ (8,954)
Net loss per common share, basic and diluted	$ (0.07)	$ (0.11)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	80,020,677	79,694,781

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]	Accumulated other Compressive Loss [Member]
Balances at beginning at Dec. 31, 2020	$ 45,547	$ 80	$ 227,912	$ (182,445)
Balances at beginning (shares) at Dec. 31, 2020		79,615,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,095		1,095
Issuance of restricted stock units under equity incentive plan		167,060
Tax withholding payments for net share-settled equity awards	(120)		(120)
Tax withholding payments for net share-settled equity awards (shares)		(59,072)
Net loss	(8,954)			(8,954)
Balances at ending at Mar. 31, 2021	37,568	$ 80	228,887	(191,399)
Balances at end (shares) at Mar. 31, 2021		79,723,680
Balances at beginning at Dec. 31, 2021	17,793	$ 80	231,068	(213,355)
Balances at beginning (shares) at Dec. 31, 2021		79,864,310
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	644		644
Issuance of restricted stock units under equity incentive plan		279,757
Tax withholding payments for net share-settled equity awards	(16)		(16)
Tax withholding payments for net share-settled equity awards (shares)		(55,251)
Sale of common stock and pre-funded warrants in public offering, net of costs of $1,034	13,766	$ 40	13,726
Sale of common stock and pre-funded warrants in public offering, net of costs (shares)		40,000,000
Net loss	(5,724)			(5,724)
Foreign currency translation adjustment	(2)				$ (2)
Balances at ending at Mar. 31, 2022	$ 26,461	$ 120	$ 245,422	$ (219,079)	$ (2)
Balances at end (shares) at Mar. 31, 2022		120,088,816

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Statement Of Stockholders Equity [Abstract]
Less transaction costs	$ 1,034

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (5,724)	$ (8,954)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	492	489
Non-cash lease expense	71	76
Stock-based compensation expense	644	1,095
Change in fair value of stock warrants	(27)	(201)
Change in fair value of contingent consideration	(858)	(987)
Other non-cash reconciling items	(2)
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	114	98
Accounts payable	(1,046)	1,180
Accrued compensation	(130)	(594)
Accrued clinical trial site costs	101	351
Operating lease liabilities	(34)	(82)
Other liabilities	37	41
Net cash used in operating activities	(6,362)	(7,488)
Cash flows from investing activities:
Purchases of property and equipment		(4)
Net cash used in investing activities		(4)
Cash flows from financing activities:
Proceeds from sale of common stock and pre-funded warrants, net of costs	14,048
Tax withholding payments for net share-settled equity awards	(16)	(120)
Principal paid on finance lease liabilities		(5)
Net cash provided by (used in) financing activities	14,032	(125)
Net increase (decrease) in cash and cash equivalents	7,670	(7,617)
Cash and cash equivalents, beginning of period	21,304	49,224
Cash and cash equivalents, end of period	28,974	$ 41,607
Supplemental disclosure of non-cash activities
Unpaid costs for issuing common stock and pre-funded warrants	$ 282

Overview

Overview	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Overview	Note 1. Overview Soleno Therapeutics, Inc. (the Company or Soleno) is focused on the development and commercialization of novel therapeutics for the treatment of rare diseases. Its lead candidate is Diazoxide Choline Extended Release tablets (DCCR), a once-daily oral tablet for the treatment of Prader-Willi Syndrome (PWS). DCCR has received orphan designation for the treatment of PWS in the United States (U.S.) as well as in the European Union (E.U.). The Company incorporated in the State of Delaware on August 25, 1999, and is located in Redwood City, California. It 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, the Company merged with Essentialis, Inc (Essentialis) and subsequently received stockholder approval to amend its Amended and Restated Certificate of Incorporation to change its name from “Capnia, Inc.” to “Soleno Therapeutics, Inc.” Essentialis was a privately held clinical-stage company focused on the development of breakthrough medicines for the treatment of rare diseases where there is increased mortality and risk of cardiovascular and endocrine complications.

Going Concern and Management's

Going Concern and Management's Plans	3 Months Ended
	Mar. 31, 2022
Cash And Cash Equivalents [Abstract]
Going Concern and Management's Plans	Note 2. Going Concern and Management’s Plans The Company had a net loss of $5.7 million during the three months ended March 31, 2022 and has an accumulated deficit of $219.1 million at March 31, 2022 resulting from having incurred losses since its inception. The Company had $29.0 s of March 31, 2022. 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, obtain regulatory approval 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 are critical to the realization of its business plan and the future operations of the Company. 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 through at least the next twelve months from the date of this filing.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 3. Basis of Presentation and Summary of Significant Accounting Policies Significant Accounting Policies There have been no material changes to the significant accounting policies during the three months ended March 31, 2022 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, 2021. 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, 2022, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2022. 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, 2021, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 31, 2022. 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, accrued costs for services rendered in connection with third-party contractor clinical trial activities, and the valuation of contingent liabilities for the purchase price of assets obtained through acquisition. 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. During the three months ended March 31, 2022, there have been no recently adopted accounting standards and 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, 2022
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 — Unadjusted quoted prices in active markets for identical assets or liabilities; • Level II — Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices 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 related assets or liabilities; and • Level III — Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. 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, 2022 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 4 $ — $ — $ 4 Essentialis purchase price contingency liability 8,689 — — 8,689 Total common stock warrant and contingent consideration liability $ 8,693 $ — $ — $ 8,693 Fair Value Measurements at December 31, 2021 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 31 $ — $ — $ 31 Essentialis purchase price contingency liability 9,547 — — 9,547 Total common stock warrant and contingent consideration liability $ 9,578 $ — $ — $ 9,578 The Company’s estimated fair value of the 2018 PIPE Warrants was calculated 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 expected term, the expected dividend yield and the risk-free interest rate. Based on the terms of the Company’s completed merger with Essentialis on March 7, 2017, the Company was obligated to make cash earnout payments of up to a maximum of $30.0 million to the former Essentialis stockholders. On December 28, 2021, in connection with the dissolution of two of the former Essentialis stockholders, the two former stockholders entered into an agreement with the Company which assigned the right, title and interest to all their future earnout payments to the Company. As a result of the assignment, as of December 31, 2021, and going forward, the maximum cash earnout payments are $21.2 million. 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 (FDA) The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. 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 for the three months ended March 31, 2022 and 2021 (dollars in thousands). 2018 PIPE Warrants Purchase Price Number of Warrants Liability Contingent Liability Balance at January 1, 2022 513,617 $ 31 $ 9,547 Change in value of 2018 PIPE Warrants — (27 ) — Change in value of contingent liability — — (858 ) Balance at March 31, 2022 513,617 $ 4 $ 8,689 2018 PIPE Warrants Purchase Price Number of Warrants Liability Contingent Liability Balance at January 1, 2021 513,617 $ 539 $ 10,278 Change in value of 2018 PIPE Warrants — (201 ) — Change in value of contingent liability — — (987 ) Balance at March 31, 2021 513,617 $ 338 $ 9,291

Warrant Liabilities

Warrant Liabilities	3 Months Ended
	Mar. 31, 2022
Text Block [Abstract]
Warrant Liabilities	Note 5. Warrant Liabilities The Company has issued multiple warrant series, of which the 2018 PIPE Warrants were determined to be liabilities pursuant to the guidance established by ASC 815 Derivatives and Hedging. 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 to purchase 513,617 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. Since the Company may be obligated to settle the 2018 PIPE Warrants in cash, the Company classified the 2018 PIPE Warrants as long-term liabilities at their fair value and will re-measure the warrants at each balance sheet date until they are exercised or expire. Any change in the fair value is recognized as other income (expense) in the Company’s condensed consolidated statements of operations. As of March 31, 2022, the fair value of the 2018 PIPE Warrants was estimated at approximately $ 4,000 0.2 The Company has calculated the fair value of the 2018 PIPE Warrants using a Black-Scholes pricing model. The following summarizes certain key assumptions used in estimating the fair value. March 31, 2022 March 31, 2021 Volatility 87 % 105 % Contractual term (years) 1.7 2.7 Expected dividend yield — % — % Risk-free rate 2.10 % 0.30 % The Black-Scholes pricing model • Volatility: The Company calculates the estimated volatility rate based its historical volatility over the expected life of the warrants. • 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 the expected life of the warrants.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 6. Commitments and Contingencies Facility Leases The The lease was recognized at inception with a right-of-use asset equal to $0.6 million and a liability for $0.5 million. The short-term liability was equal to $0.3 million as of both March 31, 2022 and December 31, 2021, and the long-term liability was equal to $0.1 million and $0.2 million, as of March 31, 2022 and December 31, 2021, respectively. The weighted average discount rate was 9% over a remaining term of 14 months. The discount rate was determined based on estimates of the Company’s incremental borrowing rate, as the discount rate implicit in the lease cannot be readily determined. The following is a schedule by year of future maturities of the Company’s operating lease liabilities as of March 31, 2022 (in thousands): 2022 (remainder of the year) $ 291 2023 159 Total lease payments 450 Less interest (27 ) Total $ 423 The components of lease expense during the three months ended March 31, 2022 and 2021 were as follows (in thousands): Three Months Ended March 31, 2022 2021 Operating lease cost: Operating lease cost $ 81 $ 76 Variable lease cost — 3 Short-term lease cost 5 7 Total operating lease cost $ 86 $ 86 Finance lease cost: Amortization of right-of-use assets $ — $ 2 Interest on lease liabilities — — Total finance lease cost $ — $ 2 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.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Stockholders' Equity	Note 7. Stockholders’ Equity Underwritten Public Offering On March 31, 2022, the Company sold 40,000,000 shares of its common stock at a public offering price of $0.25, and for certain investors, in lieu of common stock, pre-funded warrants (the 2022 pre-funded warrants) to purchase 20,000,000 shares of its common stock at a public offering price of $0.24 per pre-funded warrant, which represents the per share public offering price for the common stock less the $0.01 per share exercise price for each 2022 pre-funded warrant. The 2022 pre-funded warrants are immediately exercisable and may be exercised at any time until all of the 2022 pre-funded warrants are exercised in full. Each share of common stock or 2022 pre-funded warrant was sold together with one, immediately exercisable, common warrant (the 2022 common warrants) with a five year term to purchase one share of common stock at an exercise price of $0.30 per share. The net proceeds of the offering were $13.8 million, after deducting the underwriting discount and other estimated offering expenses, of which $0.3 million remains to be paid as of March 31, 2022 . The Company is not required under any circumstance to settle any of the 2022 pre-funded warrants or the 2022 common warrants for cash, and therefore classified both types of warrants as permanent equity. Other Common Stock Warrants As of March 31, 2022, 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. Equity Incentive Plans 2014 Plan The Company maintains the 2014 Equity Incentive Plan (the 2014 Plan). Under the 2014 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 2014 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 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 for service-based stock options is normally monthly over a period of 4 years from the vesting date. Performance-based grants have vesting contingent upon the achievement of certain performance criteria related to the Company’s commercialization of its therapeutics. 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, 2022, a total of 2,805,045 shares are available for future grant under the 2014 Plan. Inducement Plan The Company maintains the In accordance with Rule 5635(c)(4) and Rule 5635(c)(3) of the Nasdaq Listing Rules, awards under the Inducement Plan may only be made to individuals not previously employees or non-employee directors of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company, or, to the extent permitted by Rule 5635(c)(3) of the Nasdaq Listing Rules, in connection with a merger or acquisition. As of March 31, 2022, a total of 1,285,000 shares are available for future grant under the Inducement Plan. Stock-based compensation expense 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 condensed consolidated 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, 2022 2021 Research and development $ 160 $ 189 General and administrative 484 906 Total $ 644 $ 1,095 Stock Options The Company granted options to purchase 1,627,750 and 3,168,500 shares of the Company’s common stock during the three months ended March 31, 2022 and 2021, respectively. Of the total options granted during the three months ended March 31, 2021, 708,750 were performance-based options. Three Months Ended March 31, 2022 2021 Expected life (years) 6.0 5.5-6.0 Risk-free interest rate 1.7% 0.6%-0.7% Volatility 88% 99%-108% 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 period of time that the options are expected to be outstanding. Due to the lack of historical exercise history, the expected life of the Company’s service-based stock options has been determined utilizing the “simplified method”, based on the average of the contractual term of the options and the weighted-average vesting period. The expected life for the performance-based options was determined based on consideration of the contractual term of the stock options, an estimate of the date the performance criteria would be met and expectations of employee behavior. • 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 life of the stock options. • Volatility: The estimated volatility rate is based on the volatilities of the Company’s common stock for a historical period equal to the expected life of the stock options. • 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, 2022 as issued under the 2014 Plan and the Inducement Plan: Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding Share (in years) (in thousands) Balance at January 1, 2022 6,125,549 $ 3.09 7.94 Options granted 1,627,750 $ 0.34 Options exercised — Options canceled/forfeited (6,625 ) $ 2.17 Balance at March 31, 2022 7,746,674 $ 2.51 8.06 $ — Options vested at March 31, 2022 3,125,931 $ 3.92 6.69 $ — Options vested and expected to vest at March 31, 2022 7,402,299 $ 2.52 8.11 $ — The weighted-average grant date fair value of options granted was $0.25 and $1.79 per share for the three months ended March 31, 2022 and 2021, respectively. At March 31, 2022 total unrecognized employee stock-based compensation related to stock options that are likely to vest was $4.4 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.9 years. Restricted Stock Units There were 134,507 and 21,810 restricted stock units granted by the Company during the three months ended March 31, 2022 and 2021, respectively, to employees and directors. The restricted stock units granted to directors were 100% vested on the grant date and represent compensation for past board services. The restricted stock units granted to employees typically vest annually over a period of four years. The restricted stock units 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, 2022 as issued under the 2014 Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at January 1, 2022 435,750 $ 3.85 Restricted stock units granted 134,507 0.36 Restricted stock units vested (279,757 ) 0.37 Restricted stock units canceled/forfeited (2,000 ) 3.85 Outstanding at March 31, 2022 288,500 $ 3.85 The weighted-average grant-date fair value of all restricted stock units granted during the three months ended March 31, 2022 and 2021 was $0.36 and $1.96, respectively. The fair value of all restricted stock units vested during the three months ended March 31, 2022 and 2021 was $0.1 million and approximately $0.6 million, respectively. At March 31, 2022, total unrecognized employee stock-based compensation related to restricted stock units was $1.0 million, which is expected to be recognized over the weighted-average remaining vesting period of 1.8 years. 2014 Employee Stock Purchase Plan The Company’s board of directors and stockholders have adopted the 2014 Employee Stock Purchase Plan (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% • 55,936 • such amount as determined by the board of directors. As of March 31, 2022, there were no purchases by employees under this plan.

Net loss per share

Net loss per share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net loss per share	Note 8. 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 or vesting of common stock awards and exercise of common stock warrants. The Company applies the two-class method to calculate basic and diluted net loss per share as its warrants issued in March 2022 are participating securities. However, the two-class method does not impact the net loss per share of common stock as the warrants issued in March 2022 do not participate in losses. For the three months ended March 31, 2022 and 2021, the effect of issuing potential common stock is anti-dilutive due to the net losses in those periods and therefore the number of shares used to compute basic and diluted net loss 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 for the periods presented because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of March 31, 2022 2021 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 7,746,674 6,006,239 Outstanding restricted stock units 288,500 435,750 Warrants issued to underwriter to purchase common stock 16,500 16,500 2018 PIPE warrants 513,617 513,617 2022 common warrants 60,000,000 — 2022 pre-funded warrants 20,000,000 — Total 88,667,361 7,074,176

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Note 9. Subsequent Events The Company has evaluated its subsequent events from March 31, 2022 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.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
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, 2022, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2022. 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, 2021, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 31, 2022.
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, accrued costs for services rendered in connection with third-party contractor clinical trial activities, and the valuation of contingent liabilities for the purchase price of assets obtained through acquisition.
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. During the three months ended March 31, 2022, there have been no recently adopted accounting standards and 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, 2022
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, 2022 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 4 $ — $ — $ 4 Essentialis purchase price contingency liability 8,689 — — 8,689 Total common stock warrant and contingent consideration liability $ 8,693 $ — $ — $ 8,693 Fair Value Measurements at December 31, 2021 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 31 $ — $ — $ 31 Essentialis purchase price contingency liability 9,547 — — 9,547 Total common stock warrant and contingent consideration liability $ 9,578 $ — $ — $ 9,578
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 for the three months ended March 31, 2022 and 2021 (dollars in thousands). 2018 PIPE Warrants Purchase Price Number of Warrants Liability Contingent Liability Balance at January 1, 2022 513,617 $ 31 $ 9,547 Change in value of 2018 PIPE Warrants — (27 ) — Change in value of contingent liability — — (858 ) Balance at March 31, 2022 513,617 $ 4 $ 8,689 2018 PIPE Warrants Purchase Price Number of Warrants Liability Contingent Liability Balance at January 1, 2021 513,617 $ 539 $ 10,278 Change in value of 2018 PIPE Warrants — (201 ) — Change in value of contingent liability — — (987 ) Balance at March 31, 2021 513,617 $ 338 $ 9,291

Warrant Liabilities (Tables)

Warrant Liabilities (Tables)	3 Months Ended
	Mar. 31, 2022
2018 PIPE Warrant Liability [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The following summarizes certain key assumptions used in estimating the fair value. March 31, 2022 March 31, 2021 Volatility 87 % 105 % Contractual term (years) 1.7 2.7 Expected dividend yield — % — % Risk-free rate 2.10 % 0.30 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Reconciliation of Undiscounted Future Minimum Lease Payments Remaining under Operating Lease	The following is a schedule by year of future maturities of the Company’s operating lease liabilities as of March 31, 2022 (in thousands): 2022 (remainder of the year) $ 291 2023 159 Total lease payments 450 Less interest (27 ) Total $ 423
Schedule of Components of Lease Expense	The components of lease expense during the three months ended March 31, 2022 and 2021 were as follows (in thousands): Three Months Ended March 31, 2022 2021 Operating lease cost: Operating lease cost $ 81 $ 76 Variable lease cost — 3 Short-term lease cost 5 7 Total operating lease cost $ 86 $ 86 Finance lease cost: Amortization of right-of-use assets $ — $ 2 Interest on lease liabilities — — Total finance lease cost $ — $ 2

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2022
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, 2022 2021 Research and development $ 160 $ 189 General and administrative 484 906 Total $ 644 $ 1,095
Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model	The fair value of each award granted was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions Three Months Ended March 31, 2022 2021 Expected life (years) 6.0 5.5-6.0 Risk-free interest rate 1.7% 0.6%-0.7% Volatility 88% 99%-108% Dividend rate — % — %
Summary of Stock Option Transactions	The following table summarizes stock option transactions for the three months ended March 31, 2022 as issued under the 2014 Plan and the Inducement Plan: Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding Share (in years) (in thousands) Balance at January 1, 2022 6,125,549 $ 3.09 7.94 Options granted 1,627,750 $ 0.34 Options exercised — Options canceled/forfeited (6,625 ) $ 2.17 Balance at March 31, 2022 7,746,674 $ 2.51 8.06 $ — Options vested at March 31, 2022 3,125,931 $ 3.92 6.69 $ — Options vested and expected to vest at March 31, 2022 7,402,299 $ 2.52 8.11 $ —
Summary of Restricted Stock Unit Transactions	The following table summarizes restricted stock unit transactions for the three months ended March 31, 2022 as issued under the 2014 Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at January 1, 2022 435,750 $ 3.85 Restricted stock units granted 134,507 0.36 Restricted stock units vested (279,757 ) 0.37 Restricted stock units canceled/forfeited (2,000 ) 3.85 Outstanding at March 31, 2022 288,500 $ 3.85

Net loss per share (Tables)

Net loss per share (Tables)	3 Months Ended
	Mar. 31, 2022
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 for the periods presented because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of March 31, 2022 2021 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 7,746,674 6,006,239 Outstanding restricted stock units 288,500 435,750 Warrants issued to underwriter to purchase common stock 16,500 16,500 2018 PIPE warrants 513,617 513,617 2022 common warrants 60,000,000 — 2022 pre-funded warrants 20,000,000 — Total 88,667,361 7,074,176

Going Concern and Management'_2

Going Concern and Management's Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash And Cash Equivalents [Line Items]
Net loss		$ (5,724)	$ (8,954)
Accumulated deficit	$ (219,079)	(219,079)		$ (213,355)
Cash and cash equivalents	$ 28,974	28,974		$ 21,304
Net cash used in operating activities		$ (6,362)	$ (7,488)
Underwritten Public Offering [Member]
Cash And Cash Equivalents [Line Items]
Issuance of common stock (shares)	40,000,000	40,000,000
Number of common stock purchased upon issuance of warrants	20,000,000	20,000,000
Per share exercise price for pre-funded warrant	$ 0.01	$ 0.01
Proceeds from sale of common stock, net of costs	$ 13,800
Payments of underwriting discount and other estimated offering costs		$ 300

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, 2022	Dec. 31, 2021
Liabilities
Contingent liability for Essentialis purchase price	$ 8,689	$ 9,547
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	4	31
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	8,693	9,578
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	4	31
Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	8,689	9,547
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	8,693	9,578
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	4	31
Level 3 [Member] | Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 8,689	$ 9,547

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 07, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Percentage of probability of achieving milestone	72.00%	72.00%
Essentialis, Inc. [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Maximum potential cash earnout payments		$ 21.2	$ 30

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 3 Financial Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 9,547	$ 10,278
Change in value of liabilities	(858)	(987)
Balance at end of period	8,689	9,291
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	$ 31	$ 539
Balance at the beginning of period, in shares	513,617	513,617
Change in value of liabilities	$ (27)	$ (201)
Balance at end of period	$ 4	$ 338
Balance at the end of period, in shares	513,617	513,617

Warrant Liabilities - Additiona

Warrant Liabilities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2022USD ($)$ / shares	Mar. 31, 2021USD ($)	Dec. 19, 2018$ / sharesshares
Class Of Warrant Or Right [Line Items]
Change in fair value of stock warrants	$ (27,000)	$ (201,000)
Expected Dividend Yield [Member]
Class Of Warrant Or Right [Line Items]
Measurement input	0
2018 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares			513,617
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 to purchase 513,617 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.
Fair value of estimated warrants	$ 4,000
Change in fair value of stock warrants	$ (27,000)	$ (200,000)
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, 2022	Mar. 31, 2021
Volatility [Member] | 2018 PIPE Warrant Liability [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.87	1.05
Contractual Term [Member] | 2018 PIPE Warrant Liability [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	1 year 8 months 12 days	2 years 8 months 12 days
Expected Dividend Yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0
Risk-free Rate [Member] | 2018 PIPE Warrant Liability [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0210	0.0030

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		3 Months Ended
	Apr. 30, 2021ft²	Jul. 31, 2019USD ($)	Mar. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Jun. 30, 2021USD ($)
Commitments And Contingencies [Line Items]
Right-of-use asset			$ 350,000	$ 421,000	$ 600,000
Right-of-use liability			423,000
Operating lease, short-term liability			344,000	282,000
Operating lease, long-term liability			$ 79,000	175,000
Operating lease, weighted average discount rate			9.00%
Operating lease remaining term			14 months
Facility Leases [Member]
Commitments And Contingencies [Line Items]
Right-of-use liability			$ 500,000
Operating lease, long-term liability			$ 100,000	$ 200,000
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 operating lease agreement for the same 6,368 square feet of space, which began in June 2021 and expires in May 2023.
Operating lease beginning date	2021-06
Operating lease, expiration	2023-05	2021-05
Payment to acquire office furniture under operating lease		$ 1

Commitments and Contingencies_2

Commitments and Contingencies - Reconciliation of Undiscounted Future Minimum Lease Payments Remaining under Operating Lease (Detail) $ in Thousands	Mar. 31, 2022USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022 (remainder of the year)	$ 291
2023	159
Total lease payments	450
Less interest	(27)
Right-of-use liability	$ 423

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 81	$ 76
Variable lease cost		3
Short-term lease cost	5	7
Total operating lease cost	$ 86	86
Amortization of right-of-use assets		2
Total finance lease cost		$ 2

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
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)		$ 0.25	$ 1.79
Number of shares available for issuance under the plan on the first day of each year	120,088,816	120,088,816		79,864,310
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%	10.00%
2020 Inducement Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant	1,285,000	1,285,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Income tax benefits recognized from stock-based compensation		$ 0	$ 0
Number of options granted		1,627,750	3,168,500
Future stock-based compensation for unvested employee options granted and outstanding	$ 4,400,000	$ 4,400,000
Future stock-based compensation, requisite service period		2 years 10 months 24 days
Stock Options [Member] | 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		4 years
Number of shares available for grant	2,805,045	2,805,045
Stock Options [Member] | 2014 Equity Incentive Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value		110.00%
Stock Options [Member] | 2014 Equity Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option		10 years
ISOs [Member] | 2014 Equity Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option		5 years
Performance-Based Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted			708,750
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		4 years
Stock units granted		134,507	21,810
Vesting percentage		100.00%
Weighted average grant-date fair value of all restricted stock units granted		$ 0.36	$ 1.96
Fair value of restricted stock units vested		$ 100,000	$ 600,000
Unrecognized stock based compensation expense	$ 1,000,000	$ 1,000,000
Weighted average remaining vesting period		1 year 9 months 18 days
Restricted Stock Units [Member] | 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units granted		134,507
Weighted average grant-date fair value of all restricted stock units granted		$ 0.36
Warrants to Purchase Stock [Member] | 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants (in dollars per share)	$ 24.35	$ 24.35
Warrants outstanding (in shares)	102,070	102,070
Warrants term		10 years
Warrants expiration period		2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants (in dollars per share)	$ 35.70	$ 35.70
Warrants outstanding (in shares)	16,500	16,500
Warrants term		10 years
Warrants expiration period		2024-11
Underwritten Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (shares)	40,000,000	40,000,000
Price per unit	$ 0.25	$ 0.25
Number of common stock purchased upon issuance of warrants	20,000,000	20,000,000
Public offering price per pre-funded warrant	$ 0.24	$ 0.24
Per share exercise price for pre-funded warrant	$ 0.01	$ 0.01
Measurement term	5 years	5 years
Exercise price of warrants (in dollars per share)	$ 0.30	$ 0.30
Proceeds from offering after deducting underwriting discount and other estimated offering expenses		$ 13,800,000
Payments of underwriting discount and other estimated offering costs		$ 300,000
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant	27,967	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	55,936
Number of shares purchases by employees		0

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 644	$ 1,095
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	160	189
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 484	$ 906

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	6 years
Risk-free interest rate	1.70%
Volatility	88.00%
Dividend rate	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)		5 years 6 months
Risk-free interest rate		0.60%
Volatility		99.00%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)		6 years
Risk-free interest rate		0.70%
Volatility		108.00%

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Transactions (Detail) - Stock Options [Member] - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted	1,627,750	3,168,500
2014 Plan and Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	6,125,549
Options granted	1,627,750
Options canceled/forfeited	(6,625)
Ending balance	7,746,674		6,125,549
Options vested at end of period (shares)	3,125,931
Options vested and expected to vest at end of period (shares)	7,402,299
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 3.09
Options granted (in dollars per share)	0.34
Options canceled/forfeited (in dollars per share)	2.17
Ending balance (in dollars per share)	2.51		$ 3.09
Options vested at end of period (in dollars per share)	3.92
Options vested and expected to vest at end of period (in dollars per share)	$ 2.52
Weighted Average Remaining Contractual Term
Options outstanding at end of period	8 years 21 days		7 years 11 months 8 days
Options vested at end of period	6 years 8 months 8 days
Options vested and expected to vest at end of period	8 years 1 month 9 days

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Restricted Stock Unit Transactions (Detail) - Restricted Stock Units [Member] - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock units granted	134,507	21,810
Weighted-average grant date fair value
Restricted stock units granted (in dollars per share)	$ 0.36	$ 1.96
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance	435,750
Restricted stock units granted	134,507
Restricted stock units vested	(279,757)
Restricted stock units canceled/forfeited	(2,000)
Ending balance	288,500
Weighted-average grant date fair value
Beginning balance (in dollars per share)	$ 3.85
Restricted stock units granted (in dollars per share)	0.36
Restricted stock units vested (in dollars per share)	0.37
Restricted stock units canceled/forfeited (in dollars per shares)	3.85
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, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	88,667,361	7,074,176
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	7,746,674	6,006,239
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	288,500	435,750
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
2022 Common Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	60,000,000
2022 Pre-funded Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	20,000,000
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