Soleno Therapeutics (SLNO) 10-Q 5 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
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		79,723,680
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, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 41,607	$ 49,224
Prepaid expenses and other current assets	921	1,019
Total current assets	42,528	50,243
Long-term assets
Property and equipment, net	20	19
Operating lease right-of-use assets	50	124
Finance lease right-of-use assets	13	15
Intangible assets, net	14,095	14,581
Total assets	56,706	64,982
Current liabilities
Accounts payable	4,669	3,489
Accrued compensation	411	1,005
Accrued clinical trial site costs	4,140	3,789
Operating lease liabilities	57	139
Other current liabilities	232	196
Total current liabilities	9,509	8,618
Long-term liabilities
Contingent liability for Essentialis purchase price	9,291	10,278
Total liabilities	19,138	19,435
Commitments and contingencies (Note 6)
Stockholders’ equity
Common stock, $0.001 par value, 250,000,000 shares authorized, 79,723,680 and 79,615,692 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively.	80	80
Additional paid-in-capital	228,887	227,912
Accumulated deficit	(191,399)	(182,445)
Total stockholders’ equity	37,568	45,547
Total liabilities and stockholders’ equity	56,706	64,982
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 338	$ 539

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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	79,723,680	79,615,692
Common stock, shares outstanding	79,723,680	79,615,692

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses
Research and development	$ 7,164	$ 6,695
General and administrative	2,979	2,003
Change in fair value of contingent consideration	(987)	584
Total operating expenses	9,156	9,282
Operating loss	(9,156)	(9,282)
Other income
Change in fair value of warrants liabilities	201	3,413
Interest income	1	11
Total other income	202	3,424
Net loss	$ (8,954)	$ (5,858)
Net loss per common share, basic and diluted	$ (0.11)	$ (0.13)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	79,694,781	44,679,858

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, 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	392		392
Issuance of common stock under equity incentive plan (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
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 common stock under equity incentive plan (shares)		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

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (8,954)	$ (5,858)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	489	489
Non-cash lease expense	76	68
Stock-based compensation expense	1,095	392
Change in fair value of stock warrants	(201)	(3,413)
Change in fair value of contingent consideration	(987)	584
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	98	(161)
Accounts payable	1,180	1,485
Accrued compensation	(594)	55
Accrued clinical trial site costs	351	847
Operating lease liabilities	(82)	10
Other liabilities	41	(157)
Net cash used in operating activities	(7,488)	(5,659)
Cash flows from investing activities:
Purchases of property and equipment	(4)
Net cash used in investing activities	(4)
Cash flows from financing activities:
Tax withholding payments for net share-settled equity awards	(120)
Principal paid on finance lease liabilities	(5)	(4)
Net cash used in financing activities	(125)	(4)
Net decrease in cash and cash equivalents	(7,617)	(5,663)
Cash and cash equivalents, beginning of period	49,224	20,733
Cash and cash equivalents, end of period	$ 41,607	$ 15,070

Overview

Overview	3 Months Ended
	Mar. 31, 2021
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 Controlled 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. DCCR has been evaluated in a Phase 3 study (C601 or DESTINY PWS), a 3-month randomized, double-blind placebo-controlled study, which completed enrollment in January 2020, with 127 patients at 29 sites in the U.S. and U.K. Patients who complete treatment in DESTINY PWS are eligible to receive DCCR for up to 36 months in C602, an open-label extension study. Top line results from DESTINY PWS were announced in June 2020. Although the trial did not meet its primary endpoint of change from baseline in hyperphagia, significant improvements were observed in two of three key secondary endpoints. In February 2021, the Company announced analysis limited to data collected before the onset of the COVID-19 pandemic. The analysis of the data through March 1, 2020 showed statistical significance in the primary, all key secondary and several other efficacy endpoints. In March 2021, the U.S. Food and Drug Administration (FDA) informed the Company that an additional clinical trial would be necessary to support a New Drug Approval submission.

Liquidity

Liquidity	3 Months Ended
	Mar. 31, 2021
Cash And Cash Equivalents [Abstract]
Liquidity	Note 2. Liquidity The Company had a net loss of $9.0 million during the three months ended March 31, 2021 and has an accumulated deficit of $191.4 million at March 31, 2021 resulting from having incurred losses since its inception. The Company had $41.6

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
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, 2021 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, 2020. 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, 2021, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2021. 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, 2020, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 3, 2021. 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, value and life of acquired intangibles, and the valuation of contingent liabilities for the purchase price of assets obtained through acquisition. 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. During the three months ended March 31, 2021, 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, 2021
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, 2021 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 338 $ — $ — $ 338 Essentialis purchase price contingency liability 9,291 — — 9,291 Total common stock warrant and contingent consideration liability $ 9,629 $ — $ — $ 9,629 Fair Value Measurements at December 31, 2020 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 539 $ — $ — $ 539 Essentialis purchase price contingency liability 10,278 — — 10,278 Total common stock warrant and contingent consideration liability $ 10,817 $ — $ — $ 10,817 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. Through March 31, 2020 the Company had previously used the Monte Carlo simulation of a geometric Brownian motion model to estimate the fair value of the 2018 PIPE Warrant as this model allows for determining path-dependent outcomes. The difference in valuation as a result of using the Black-Scholes pricing model compared to the Monte Carlo simulation model is not significant. 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 FDA as well as reaching cumulative revenue milestones. 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, 2021 and 2020 (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 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 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 January 1, 2020 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, 2021
Text Block [Abstract]
Warrant Liabilities	Note 5. Warrant Liabilities The Company has issued multiple warrant series, of which the Series C Warrants, the 2017 PIPE Warrants and the 2018 PIPE Warrants (Warrants) were determined to be liabilities pursuant to the guidance established by ASC 815 Derivatives and Hedging. Accounting Treatment The Company accounts for Warrants in accordance with the guidance in ASC 815 Series C Warrants The Series C Warrants expired in March 2020. The Company calculated the fair value of the Series C Warrants as of January 1, 2020 using a Black-Scholes pricing model. 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 prior to their expiration on December 15, 2020, entitled the holders to purchase 6,024,425 of the Company’s common stock at an exercise price equal to $2.00 per share, subject to certain adjustments. No warrants were exercised prior to expiration. The Company calculated the fair value of the 2017 PIPE Warrants as of January 1, 2020 using a Monte Carlo simulation of a geometric Brownian motion model. The $ 3.2 million decrease in the fair value of the liability for the 2017 PIPE Warrants during the three months ended March 31, 2020 was recorded as other income in the condensed consolidated statements of operations. Warrants Issued as Part of the Units in the 2018 PIPE Offering The 2018 PIPE Warrants were issued on December 19, 2018 in a 2018 private offering of common stock and warrants (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. As of March 31, 2021, the fair value of the 2018 PIPE Warrants was estimated at $ 0.3 million 0.2 The Company has calculated the fair value of the 2018 PIPE Warrants as of March 31, 2021 and December 31, 2020 using a Black-Scholes pricing model which 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, 2021 December 31, 2020 Volatility 105 % 88 % Contractual term (years) 2.7 3.0 Expected dividend yield — % — % Risk-free rate 0.30 % 0.17 % 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 those of expected volatility.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 6. Commitments and Contingencies Facility Leases In July 2019, the Company executed a non-cancellable lease agreement for 6,368 square feet of 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. Also see Note 9, Subsequent Events , for The components of lease expense during the three months ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Operating lease cost $ 76 $ 76 Finance lease cost: Amortization of right-of-use assets $ 2 $ 2 Interest on lease liabilities — 1 Total finance lease cost $ 2 $ 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.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Stockholders' Equity	Note 7. Stockholders’ Equity Equity Incentive Plans 2014 Plan The Company has adopted 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, 2021, a total of 1,426,546 shares are available for future grant under the 2014 Plan. Inducement Plan On September 28, 2020, the Company adopted the 2020 Inducement Equity Incentive Plan (the Inducement Plan) and, subject to the adjustment provisions of the Inducement Plan, reserved 1,500,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan. The Inducement Plan provides for the grant of equity-based awards, including nonstatutory stock options, restricted stock units, restricted stock, stock appreciation rights, performance shares and performance units, and its terms are substantially similar to the 2014 Plan. 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. There have been no awards granted under the Inducement Plan as of March 31, 2021. As of March 31, 2021, a total of 1,500,000 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 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, 2021 2020 Research and development $ 189 $ 99 General and administrative 906 293 Total $ 1,095 $ 392 Stock Options The Company granted options to purchase 3,168,500 and zero shares of the Company’s common stock during the three months ended March 31, 2021 and 2020, 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, 2021 Expected life (years) 5.5-6.0 Risk-free interest rate 0.6%-0.7% Volatility 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 term 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 time to liquidity. • 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, 2021 as issued under the 2014 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, 2021 2,837,739 $ 4.18 7.62 Options granted 3,168,500 $ 2.24 Options exercised — Options canceled/forfeited — Balance at March 31, 2021 6,006,239 $ 3.15 8.64 $ — Options vested at March 31, 2021 1,992,693 $ 4.93 6.95 $ — Options vested and expected to vest at March 31, 2021 6,006,239 $ 3.15 8.64 $ — The weighted-average grant date fair value of options granted was $1.79 per share for the three months ended March 31, 2021. At March 31, 2021 total unrecognized employee stock-based compensation related to stock options that are likely to vest was $6.6 million, which is expected to be recognized over the weighted-average remaining vesting period of 3.3 years. Restricted Stock Units There were 21,810 and 687,257 restricted stock units granted by the Company during the three months ended March 31, 2021 and 2020, 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, 2021 as issued under the 2014 Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at January 1, 2021 581,000 $ 3.85 Restricted stock units granted 21,810 $ 1.96 Restricted stock units vested (167,060 ) $ 3.60 Outstanding at March 31, 2021 435,750 $ 3.85 The weighted-average grant-date fair value of all restricted stock units granted during the three months ended March 31, 2021 and 2020 was $1.96 and $3.83, respectively. The fair value of all restricted stock units vested during the three months ended March 31, 2021 and 2020 was $0.6 million and approximately $96,000, respectively. At March 31, 2021, total unrecognized employee stock-based compensation related to restricted stock units was $1.6 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.8 years. 2014 Employee Stock Purchase Plan The Company’s Board and stockholders have adopted the 2014 Employee Stock Purchase Plan (ESPP). The ESPP has become effective, and the Board 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 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. As of March 31, 2021, there were no purchases by employees under this plan. Common Stock Warrants As of March 31, 2021, the Company had 102,070 common stock warrants outstanding that are related to convertible notes issued in 2010 and 2012, 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, 2021
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. For the three months ended March 31, 2021 and 2020, the effect of issuing such 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 for the periods presented because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of March 31, 2021 2020 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 6,006,239 2,084,758 Outstanding restricted stock units 435,750 658,500 Warrants issued to underwriter to purchase common stock 16,500 16,500 Series D warrants to purchase common stock — 540,540 2017 PIPE warrants — 6,024,425 2018 PIPE warrants 513,617 513,617 Total 7,074,176 9,940,410

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Note 9. Subsequent Events The Company has evaluated its subsequent events from March 31, 2021 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. Lease The Company’s operating lease for its headquarters facility office space in Redwood City, California, terminates in May 2021. In April 2021, the Company executed a non-cancellable operating lease agreement for the same 6,368 square feet of space in Redwood City, California, which begins in June 2021 and expires in May 2023. Minimum rental commitments under this lease are $0.1 million during 2021, $0.3 million during 2022, and $0.2 million during 2023.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
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, 2021, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2021. 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, 2020, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 3, 2021.
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, value and life of acquired intangibles, and the valuation of contingent liabilities for the purchase price of assets obtained through acquisition. 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. During the three months ended March 31, 2021, 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, 2021
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, 2021 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 338 $ — $ — $ 338 Essentialis purchase price contingency liability 9,291 — — 9,291 Total common stock warrant and contingent consideration liability $ 9,629 $ — $ — $ 9,629 Fair Value Measurements at December 31, 2020 Total Level 1 Level 2 Level 3 Liabilities 2018 PIPE warrant liability $ 539 $ — $ — $ 539 Essentialis purchase price contingency liability 10,278 — — 10,278 Total common stock warrant and contingent consideration liability $ 10,817 $ — $ — $ 10,817
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, 2021 and 2020 (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 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 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 January 1, 2020 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, 2021
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, 2021 December 31, 2020 Volatility 105 % 88 % Contractual term (years) 2.7 3.0 Expected dividend yield — % — % Risk-free rate 0.30 % 0.17 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Components of Lease Expense	The components of lease expense during the three months ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Operating lease cost $ 76 $ 76 Finance lease cost: Amortization of right-of-use assets $ 2 $ 2 Interest on lease liabilities — 1 Total finance lease cost $ 2 $ 3

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
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, 2021 2020 Research and development $ 189 $ 99 General and administrative 906 293 Total $ 1,095 $ 392
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, 2021 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions Three Months Ended March 31, 2021 Expected life (years) 5.5-6.0 Risk-free interest rate 0.6%-0.7% Volatility 99%-108% Dividend rate — %
Summary of Stock Option Transactions	The following table summarizes stock option transactions for the three months ended March 31, 2021 as issued under the 2014 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, 2021 2,837,739 $ 4.18 7.62 Options granted 3,168,500 $ 2.24 Options exercised — Options canceled/forfeited — Balance at March 31, 2021 6,006,239 $ 3.15 8.64 $ — Options vested at March 31, 2021 1,992,693 $ 4.93 6.95 $ — Options vested and expected to vest at March 31, 2021 6,006,239 $ 3.15 8.64 $ —
Summary of Restricted Stock Unit Transactions	The following table summarizes restricted stock unit transactions for the three months ended March 31, 2021 as issued under the 2014 Plan: Number of Restricted Stock Units Weighted- Average Grant-Date Fair Value per Share Outstanding at January 1, 2021 581,000 $ 3.85 Restricted stock units granted 21,810 $ 1.96 Restricted stock units vested (167,060 ) $ 3.60 Outstanding at March 31, 2021 435,750 $ 3.85

Net loss per share (Tables)

Net loss per share (Tables)	3 Months Ended
	Mar. 31, 2021
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, 2021 2020 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 6,006,239 2,084,758 Outstanding restricted stock units 435,750 658,500 Warrants issued to underwriter to purchase common stock 16,500 16,500 Series D warrants to purchase common stock — 540,540 2017 PIPE warrants — 6,024,425 2018 PIPE warrants 513,617 513,617 Total 7,074,176 9,940,410

Liquidity - Additional Informat

Liquidity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 26, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Cash And Cash Equivalents [Line Items]
Net loss		$ (8,954)	$ (5,858)
Accumulated deficit		(191,399)		$ (182,445)
Cash and cash equivalents		41,607		$ 49,224
Net cash used in operating activities		$ (7,488)	$ (5,659)
Underwritten Public Offering [Member]
Cash And Cash Equivalents [Line Items]
Sale of common stock in public offering, net of costs, (shares)	34,848,484
Price per unit	$ 1.65
Proceeds from sale of common stock, net of costs	$ 53,700

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	Mar. 31, 2021USD ($)
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, 2021	Dec. 31, 2020
Liabilities
Contingent liability for Essentialis purchase price	$ 9,291	$ 10,278
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	338	539
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,629	10,817
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	338	539
Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	9,291	10,278
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,629	10,817
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities [Member] | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	338	539
Level 3 [Member] | Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 9,291	$ 10,278

Fair Value of Financial Instr_4

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, 2021	Mar. 31, 2020
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 10,278	$ 5,938
Change in value of liabilities	(987)	584
Balance at end of period	9,291	$ 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		118,083
Expiration of warrants, in 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		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		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	$ 539	$ 1,354
Balance at the beginning of period, in shares	513,617	513,617
Change in value of liabilities	$ (201)	$ (247)
Balance at end of period	$ 338	$ 1,107
Balance at the end of period, in shares	513,617	513,617

Warrant Liabilities - Additiona

Warrant Liabilities - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)$ / sharesshares	Mar. 31, 2020USD ($)	Dec. 19, 2018$ / sharesshares	Dec. 15, 2017$ / sharesshares
Class Of Warrant Or Right [Line Items]
Change in fair value of stock warrants	$ (201)	$ (3,413)
Expected Dividend Yield [Member]
Class Of Warrant Or Right [Line Items]
Measurement input	0
2017 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares				6,024,425
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 prior to their expiration on December 15, 2020, entitled the holders to purchase 6,024,425 of the Company’s common stock at an exercise price equal to $2.00 per share, subject to certain adjustments. No warrants were exercised prior to expiration.
Warrants exercised prior to expiration | shares	0
Change in fair value of stock warrants	$ 3,200
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 a 2018 private offering of common stock and warrants (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.
Change in fair value of stock warrants	$ 200
Fair value of estimated warrants	$ 300
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, 2021	Dec. 31, 2020
Volatility [Member] | 2018 PIPE Warrant Liability [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.05	0.88
Contractual Term [Member] | 2018 PIPE Warrant Liability [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	2 years 8 months 12 days	3 years
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	0.0030	0.0017

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - Redwood City, California [Member]	1 Months Ended				3 Months Ended
	Apr. 30, 2021ft²	Sep. 30, 2020USD ($)	Nov. 30, 2019USD ($)	Jul. 31, 2019USD ($)ft²	Mar. 31, 2021
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 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 | $		$ 30,000	$ 29,000
Subsequent Event [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 in Redwood City, California, which begins in June 2021 and expires in May 2023.
Operating lease beginning date	2021-06
Operating lease, expiration	2023-05

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 76	$ 76
Amortization of right-of-use assets	2	2
Interest on lease liabilities		1
Total finance lease cost	$ 2	$ 3

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Sep. 28, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Weighted average grant date fair value per option granted (in dollars per share)	$ 1.79
Number of shares available for issuance under the plan on the first day of each year	79,723,680		79,615,692
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
Number of shares purchases by employees	0
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%
2020 Inducement Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant	1,500,000
Number of shares reserved for issuance				1,500,000
Stock units granted	0
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	3,168,500	0
Expected dividend yield	0.00%
Future stock-based compensation for unvested employee options granted and outstanding	$ 6,600,000
Future stock-based compensation, requisite service period	3 years 3 months 18 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	1,426,546
Number of options granted	3,168,500
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	21,810	687,257
Vesting percentage	100.00%
Weighted average grant-date fair value of all restricted stock units granted	$ 1.96	$ 3.83
Fair value of restricted stock units vested	$ 600,000	$ 96,000
Unrecognized stock based compensation expense	$ 1,600,000
Weighted average remaining vesting period	2 years 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	21,810
Weighted average grant-date fair value of all restricted stock units granted	$ 1.96

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,095	$ 392
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	189	99
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 906	$ 293

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended
	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend rate	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, 2021	Mar. 31, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted	3,168,500	0
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	2,837,739
Options granted	3,168,500
Ending balance	6,006,239		2,837,739
Options vested at end of period (shares)	1,992,693
Options vested and expected to vest at end of period (shares)	6,006,239
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 4.18
Options granted (in dollars per share)	2.24
Ending balance (in dollars per share)	3.15		$ 4.18
Options vested at end of period (in dollars per share)	4.93
Options vested and expected to vest at end of period (in dollars per share)	$ 3.15
Weighted Average Remaining Contractual Term
Options outstanding at end of period	8 years 7 months 20 days		7 years 7 months 13 days
Options vested at end of period	6 years 11 months 12 days
Options vested and expected to vest at end of period	8 years 7 months 20 days

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Restricted Stock Unit Transactions (Detail) - Restricted Stock Units [Member] - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock units granted	21,810	687,257
Weighted-average grant date fair value
Restricted stock units granted (in dollars per share)	$ 1.96	$ 3.83
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	581,000
Restricted stock units granted	21,810
Restricted stock units vested	(167,060)
Ending balance	435,750
Weighted-average grant date fair value
Beginning balance (in dollars per share)	$ 3.85
Restricted stock units granted (in dollars per share)	1.96
Restricted stock units vested (in dollars per share)	3.60
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, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	7,074,176	9,940,410
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	6,006,239	2,084,758
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	435,750	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 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
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
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 (Details) - Redwood City, California [Member] $ in Millions	1 Months Ended		3 Months Ended
	Apr. 30, 2021USD ($)ft²	Jul. 31, 2019ft²	Mar. 31, 2021
Subsequent Event [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 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
Subsequent Event [Member]
Subsequent Event [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 in Redwood City, California, which begins in June 2021 and expires in May 2023.
Operating lease beginning date	2021-06
Operating lease, expiration	2023-05
Minimum rental commitments, during 2021	$ 0.1
Minimum rental commitments, during 2022	0.3
Minimum rental commitments, during 2023	$ 0.2