0000950170-23-019752 | 10-Q | XBRL Viewer

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Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 7,874,000	$ 14,602,000
Prepaid expenses and other current assets	1,253,000	1,045,000
Total current assets	9,127,000	15,647,000
Long-term assets
Property and equipment, net	22,000	26,000
Operating lease right-of-use assets	53,000	131,000
Intangible assets, net	10,207,000	10,693,000
Other long-term assets	126,000
Total assets	19,535,000	26,497,000
Current liabilities
Accounts payable	2,778,000	1,777,000
Accrued compensation	721,000	1,675,000
Accrued clinical trial site costs	3,531,000	3,222,000
Operating lease liabilities	39,000	155,000
Other current liabilities	692,000	484,000
Total current liabilities	7,761,000	7,313,000
Long-term liabilities
Contingent liability for Essentialis purchase price	9,134,000	8,835,000
Total liabilities	16,896,000	16,149,000
Commitments and contingencies (Note 6)
Stockholders’ equity
Preferred stock, $0.001 par value; 10,000,000 shares authorized, no shares issued and outstanding
Common stock, $0.001 par value, 100,000,000 shares authorized, 8,168,788 and 8,159,382 shares issued and outstanding at March 31, 2023 and December 31, 2022, respectively	8,000	8,000
Additional paid-in-capital	248,393,000	247,762,000
Accumulated deficit	(245,778,000)	(237,422,000)
Accumulated other comprehensive income	16,000
Total stockholders’ equity	2,639,000	10,348,000
Total liabilities and stockholders’ equity	19,535,000	26,497,000
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 1,000	$ 1,000

Warrants - Additional Information (Detail)	3 Months Ended
Warrants - Additional Information (Detail)	Mar. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 USD ($)	Dec. 19, 2018 $ / shares shares
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			34,241
Exercise price of warrants (in dollars per share)			$ 30.00
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 34,241 shares of the Company’s common stock at an exercise price equal to $30.00 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 \| $	$ 1,000	$ 1,000
2018 PIPE Warrant Liability [Member] \| Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants (in dollars per share)	$ 30.00

Stockholders' Equity - Summary of Restricted Stock Unit Transactions (Detail) - Restricted Stock Units [Member] - $ / shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted stock units granted	0	8,965
Weighted-average grant date fair value
Restricted stock units granted (in dollars per share)	$ 0	$ 5.40
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	19,068
Restricted stock units vested	(9,534)
Ending balance	9,534
Weighted-average grant date fair value
Beginning balance (in dollars per share)	$ 57.75
Restricted stock units granted (in dollars per share)	0.00
Restricted stock units vested (in dollars per share)	57.75
Restricted stock units canceled/forfeited (in dollars per share)	0.00
Ending balance (in dollars per share)	$ 57.75

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2023	May 04, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
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		8,168,788
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 Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating expenses
Research and development	$ 5,316	$ 3,988
General and administrative	2,854	2,643
Change in fair value of contingent consideration	299	(858)
Total operating expenses	8,469	5,773
Operating loss	(8,469)	(5,773)
Other income
Change in fair value of warrants liabilities		27
Interest income	113	22
Total other income	113	49
Net loss	(8,356)	(5,724)
Other comprehensive income (loss)
Foreign currency translation adjustment	16	(2)
Total comprehensive loss	$ (8,340)	$ (5,726)
Net loss per common share basic	$ (0.88)	$ (1.07)
Net loss per common share diluted	$ (0.88)	$ (1.07)
Weighted-average common shares outstanding used to calculate basic net loss per common share	9,447,350	5,334,712
Weighted-average common shares outstanding used to calculate diluted net loss per common share	9,447,350	5,334,712

Warrants - Fair Value of Convertible Preferred Stock Warrant Liability (Detail) - 2018 PIPE Warrant Liability [Member]	Mar. 31, 2023	Dec. 31, 2022
Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.25	1.17
Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	8 months 12 days	1 year
Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0502	0.0474

Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - USD ($) $ in Millions	May 03, 2023	Apr. 24, 2023
Subsequent Event [Line Items]
Capital received in exchange for warrants	$ 10.0
Redwood City, California [Member]
Subsequent Event [Line Items]
Lease term		24 months
Lease commencing date		Jun. 01, 2023
Lease expiration date		May 31, 2025

Net Loss per Share

3 Months Ended

Mar. 31, 2023

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. Shares of common stock that are potentially issuable for little or no cash consideration at issuance, such as the Company's pre-funded warrants issued in March 2022, are considered outstanding common stock and are included in the calculation of basic and diluted net loss per share in connection with ASC 260 Earnings Per Shares. 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 that are not pre-funded. The Company applies the two-class method to calculate basic and diluted earnings 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 2022 common warrants issued in March 2022 do not participate in losses. For the three months ended March 31, 2023 and 2022, 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 securities are the weighted-average common shares outstanding used to calculate basic and diluted net loss per common share:


	As of March 31,
	2023		2022
Common stock		8,166,385		5,334,712
2022 pre-funded warrants		1,280,965		-
Total		9,447,350		5,334,712

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,
	2023		2022
Warrants issued to 2010/2012 convertible note holders to purchase common stock		6,804		6,804
Options to purchase common stock		926,325		516,445
Outstanding restricted stock units		9,534		19,233
Warrants issued to underwriter to purchase common stock		1,100		1,100
2018 PIPE warrants		34,241		34,241
2022 common warrants		4,000,000		4,000,000
Total		4,978,004		4,577,823

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	Aug. 26, 2022 $ / shares shares	Mar. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares
Schedule Of Significant Accounting Policies [Line Items]
Reverse stock split ratio	0.0666
Reverse stock split	one-for-fifteen
Capital stock, shares authorized	110,000,000
Common stock, shares authorized	100,000,000	100,000,000	100,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred stock, par value \| $ / shares	$ 0.001	$ 0.001	$ 0.001
ASU No. 2016-13 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 01, 2023
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true

Going Concern and Management's Plans - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	May 31, 2023	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Cash And Cash Equivalents [Line Items]
Net loss		$ (8,356)	$ (5,724)
Accumulated deficit		(245,778)		$ (237,422)
Cash and cash equivalents		7,874		14,602
Net cash used in operating activities		(6,728)	$ (6,362)
Maximum [Member]
Cash And Cash Equivalents [Line Items]
Contingent receipt upon exerise of warrants and future performance of company		$ 50,000
Securities Purchase Agreement [Member] \| Forecast [Member]
Cash And Cash Equivalents [Line Items]
Sale and issuance of warrants	$ 10,000
Underwritten Public Offering [Member] \| Securities Purchase Agreement [Member]
Cash And Cash Equivalents [Line Items]
Proceeds from sale of common stock, net of costs				$ 60,000

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2023
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 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, 2023, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2023. 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, 2022, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 22, 2023.
Reverse Stock Split	Reverse Stock Split On August 26, 2022, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation in order to effectuate a reverse stock split of the Company’s issued and outstanding common stock on a one-for-fifteen basis. All common share and per share data are retrospectively restated to give effect of the split for all periods presented herein. After giving effect to the reverse stock split, the total number of shares of all classes of capital stock that the Corporation is authorized to issue is 110,000,000 shares, consisting of 100,000,000 shares of common stock, having a par value of $0.001 and 10,000,000 shares of preferred stock, having a par value of $0.001.
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.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements 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. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses of Financial Instruments, which, together with subsequent amendments, amends the requirement on the measurement and recognition of expected credit losses for financial assets held. ASU 2016-13 is effective for the Company for the annual periods beginning after December 15, 2022, including interim periods within those fiscal years, with early adoption permitted. The Company adopted this ASU effective January 1, 2023. There was no impact on the Company's financial statements upon the adoption of this ASU. Other accounting standards that have been issued or proposed by FASB or other standards-setting bodies that do not require adoption until a future date are not currently expected to have a material impact on the Company’s financial statements upon adoption.

Subsequent Events

3 Months Ended

Mar. 31, 2023

Subsequent Events [Abstract]

Subsequent Events

Note 9. Subsequent Events

On April 24, 2023, the Company entered into a twenty-four month office lease extension commencing on June 1, 2023. The lease extension is for the office where the Company is currently located in Redwood City, California. The term of the new lease expires on May 31, 2025.

On May 3, 2023, the Company announced the completion of enrollment in the randomized withdrawal phase of Study 602 and on May 8, 2023, the Company received $10.0 million capital in exchange for warrants to purchase common stock under the Securities Purchase Agreement executed in December 2022.

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (8,356)	$ (5,724)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	490	492
Non-cash lease expense	78	71
Stock-based compensation expense	631	644
Change in fair value of stock warrants		(27)
Change in fair value of contingent consideration	299	(858)
Other non-cash reconciling items	16	(2)
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(334)	114
Accounts payable	1,001	(1,046)
Accrued compensation	(954)	(130)
Accrued clinical trial site costs	309	101
Operating lease liabilities	(116)	(34)
Other liabilities	208	37
Net cash used in operating activities	(6,728)	(6,362)
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)
Net cash provided by financing activities		14,032
Net (decrease) increase in cash and cash equivalents	(6,728)	7,670
Cash and cash equivalents, beginning of period	14,602	21,304
Cash and cash equivalents, end of period	$ 7,874	28,974
Supplemental disclosure of non-cash financing information
Unpaid costs for issuing common stock and pre-funded warrants		$ 282

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2021
Commitments And Contingencies [Line Items]
Right-of-use asset	$ 53,000	$ 131,000	$ 600,000
Operating lease, short-term liability	$ 39,000	$ 155,000
Operating lease, weighted average discount rate	9.00%
Operating lease remaining term	2 months
Facility Leases [Member]
Commitments And Contingencies [Line Items]
Right-of-use liability			$ 500,000
Redwood City, California [Member]
Commitments And Contingencies [Line Items]
Operating lease, description	began in June 2021 and expires in May 2023.
Operating lease beginning date	2021-06
Operating lease, expiration	2023-05

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 631	$ 644
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	182	160
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 449	$ 484

Stockholders' Equity - Summary of Stock Option Transactions (Detail) - Stock Options [Member] - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted	240,000	108,517
2014 Plan and Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	686,574
Options granted	240,000
Options canceled/forfeited	(249)
Ending balance	926,325		686,574
Options exercisable at end of period (shares)	428,551
Options vested and expected to vest at end of period (shares)	903,367
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 28.83
Options granted (in dollars per share)	2.37
Options canceled/forfeited (in dollars per share)	2.80
Ending balance (in dollars per share)	21.98		$ 28.83
Options exercisable at end of period (in dollars per share)	34.46
Options vested and expected to vest at end of period (in dollars per share)	$ 20.61
Weighted Average Remaining Contractual Term
Options outstanding at end of period	8 years 2 months 15 days		7 years 11 months 4 days
Options exercisable at end of period	7 years 3 months 18 days
Options vested and expected to vest at end of period	8 years 3 months 10 days

Basis of Presentation and Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2023

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, 2023 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, 2022.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of the Company have been prepared on a going concern basis in accordance with 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, 2023, are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2023. 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, 2022, which are included in the Company’s annual report on Form 10-K filed with the SEC on March 22, 2023.

Reverse Stock Split

On August 26, 2022, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation in order to effectuate a reverse stock split of the Company’s issued and outstanding common stock on a one-for-fifteen basis. All common share and per share data are retrospectively restated to give effect of the split for all periods presented herein. After giving effect to the reverse stock split, the total number of shares of all classes of capital stock that the Corporation is authorized to issue is 110,000,000 shares, consisting of 100,000,000 shares of common stock, having a par value of $0.001 and 10,000,000 shares of preferred stock, having a par value of $0.001.

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.

Recently Adopted Accounting Pronouncements

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.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses of Financial Instruments, which, together with subsequent amendments, amends the requirement on the measurement and recognition of expected credit losses for financial assets held. ASU 2016-13 is effective for the Company for the annual periods beginning after December 15, 2022, including interim periods within those fiscal years, with early adoption permitted. The Company adopted this ASU effective January 1, 2023. There was no impact on the Company's financial statements upon the adoption of this ASU.

Other accounting standards that have been issued or proposed by FASB or other standards-setting bodies that do not require adoption until a future date are not currently expected to have a material impact on the Company’s financial statements upon adoption.

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 Income (Loss) [Member]
Balances at beginning at Dec. 31, 2021	$ 17,793	$ 5	$ 231,143	$ (213,355)
Balances at beginning (shares) at Dec. 31, 2021		5,324,287
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	464		464
Issuance of restricted stock units under equity incentive plan	180		180
Issuance of restricted stock units under equity incentive plan (shares)		18,650
Tax withholding payments for net share-settled equity awards	(16)		(16)
Tax withholding payments for net share-settled equity awards (shares)		(3,683)
Sale of common stock\pre-funded warrants in public offering, net of costs	13,766	$ 3	13,763
Sale of common stock\pre-funded warrants in public offering, net of costs (shares)		2,666,667
Foreign currency translation adjustment	(2)				$ (2)
Net loss	(5,724)			(5,724)
Balances at ending at Mar. 31, 2022	26,461	$ 8	245,534	(219,079)	(2)
Balances at end (shares) at Mar. 31, 2022		8,005,921
Balances at beginning at Dec. 31, 2022	10,348	$ 8	247,762	(237,422)
Balances at beginning (shares) at Dec. 31, 2022		8,159,382
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	495		495
Issuance of restricted stock units under equity incentive plan	136		136
Issuance of restricted stock units under equity incentive plan (shares)		9,534
Tax withholding payments for net share-settled equity awards (shares)		(128)
Foreign currency translation adjustment	16				16
Net loss	(8,356)			(8,356)
Balances at ending at Mar. 31, 2023	$ 2,639	$ 8	$ 248,393	$ (245,778)	$ 16
Balances at end (shares) at Mar. 31, 2023		8,168,788

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2023

Equity [Abstract]

Summary of Stock Based Compensation Expense

Stock-based compensation expense was recognized in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Research and development	$	182	$	160
General and administrative		449		484
Total	$	631	$	644

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,
	2023	2022
Expected life (years)	6.0	6.0
Risk-free interest rate	3.5%-4.0%	1.7%
Volatility	98%-99%	88%
Dividend rate	— %	— %

Summary of Stock Option Transactions

The following table summarizes stock option transactions for the three months ended March 31, 2023 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, 2023		686,574		$	28.83		7.93
Options granted		240,000			2.37
Options exercised		—			—
Options canceled/forfeited		(249	)		2.80
Balance at March 31, 2023		926,325		$	21.98		8.21	$	—
Options exercisable at March 31, 2023		428,551		$	34.46		7.30	$	—
Options vested and expected to vest at March 31, 2023		903,367		$	20.61		8.28	$	—

Summary of Restricted Stock Unit Transactions

The following table summarizes restricted stock unit transactions for the three months ended March 31, 2023 as issued under the 2014 Plan:


	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at January 1, 2023		19,068		$	57.75
Restricted stock units granted		-		$	0.00
Restricted stock units vested		(9,534	)	$	57.75
Restricted stock units canceled/forfeited		-		$	0.00
Outstanding at March 31, 2023		9,534		$	57.75

Commitments and Contingencies

3 Months Ended

Mar. 31, 2023

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 6. Commitments and Contingencies

Facility Leases

The Company’s operating lease for its headquarters facility office space in Redwood City, California began in June 2021 and expires in May 2023.

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 $39,000 and $155,000 as of March 31, 2023 and December 31, 2022, respectively. The weighted average discount rate was 9% over a remaining term of 2 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 components of lease expense during the three months ended March 31, 2023 and 2022 were as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Operating lease cost:
Operating lease cost	$	81	$	81
Short-term lease cost		10		5
Total operating lease cost	$	91	$	86

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.

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Contingent liability for Essentialis purchase price	$ 9,134	$ 8,835
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,135	8,836
Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	9,134	8,835
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	9,135	8,836
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1	1
Level 3 [Member] \| Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 9,134	$ 8,835

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

Overview

3 Months Ended

Mar. 31, 2023

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 (DCCR) Extended-Release tablets, 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. After the merger, the Company’s primary focus has been the development and commercialization of novel therapeutics for the treatment of rare diseases and the Company divested all prior business efforts.

Stockholders' Equity

3 Months Ended

Mar. 31, 2023

Equity [Abstract]

Stockholders' Equity

Note 7. Stockholders’ Equity

Convertible Preferred Stock

The Company is authorized to issue 10,000,000 shares of Preferred Stock.

Securities Purchase Agreement

On December 16, 2022, the Company entered into a Securities Purchase Agreement for a private placement (“Private Placement”) with certain entities and members of management (collectively, “Purchasers”). Pursuant to the Securities Purchase Agreement, the Company agreed to sell to the Purchasers warrants to purchase up to an aggregate of 22,598,870 shares of the Company’s common stock, at a purchase price of $0.4425 per warrant. The closing of the Private Placement occurred on May 8, 2023 (the "Issue Date"), following the satisfaction of certain closing conditions, including the completion of enrollment in the randomized withdrawal period of Study C602, an ongoing open-label extension study of DCCR for the treatment of PWS.

The warrants are separated into two tranches with 8,598,870 Tranche A Warrants and 14,000,000 Tranche B Warrants. The Tranche A warrants are exercisable for $1.75 per share, with an aggregate exercise price of up to approximately $15.0 million, and the Tranche B warrants are exercisable for $2.50 per share, with an aggregate exercise price of up to $35.0 million. The Tranche A warrants are immediately exercisable and must be exercised within 30 days of announcement of positive top-line data from the randomized withdrawal period of Study C602 and will expire if positive top-line data is not announced prior to the 3.5 year anniversary of the date of issuance. The Tranche B warrants are also immediately exercisable and expire upon the earlier of 3.5 years from the date of issuance or 30 days following receipt of U.S. Food and Drug Administration approval of DCCR for the treatment of PWS.

Underwritten Public Offering

On March 31, 2022, the Company sold 2,666,667 shares of its common stock at a public offering price of $3.75, and for certain investors, in lieu of common stock, pre-funded warrants (the 2022 pre-funded warrants) to purchase 1,333,333 shares of its common stock at a public offering price $3.60 per pre-funded warrant, which represents the per share public offering price for the common stock less the $0.15 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 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 $4.50 per share. The net proceeds of the offering were $13.8 million, after deducting the underwriting discount and other offering expenses. 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.

At the Market Offering

In July 2021, the Company entered into a Controlled Equity Offering Sales Agreement under which the Company may sell shares of its common stock having an aggregate offering price of up to $25.0 million from time to time in any method permitted by law deemed to be an “at the market” Rule 415 under the Securities Act of 1933, as amended. As of March 31, 2023, we have sold an aggregate of 104,773 shares of common stock through the at the market program, totaling $0.3 million in net proceeds.

Other Common Stock Warrants

As of March 31, 2023, the Company had 6,804 common stock warrants outstanding from the 2010/2012 convertible notes, with an exercise price of $365.25 and a term of 10 years expiring in November 2024. The Company also had 1,100 common stock warrants issued to the underwriter in the Company’s IPO, with an exercise price of $535.50 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. On March 23, 2023, the Company filed a Registration Statement on Form S-8 which registered 238,329 shares available for grant and issuance under the 2014 Plan, all of which became available for grant and issuance under the 2014 Plan on January 1, 2023.

As of March 31, 2023, a total of 15,508 shares are available for future grant under the 2014 Plan.

Inducement Plan

The Company maintains the 2020 Inducement Equity Incentive Plan (the Inducement Plan). The Inducement Plan provides for the grant of equity-based awards, including non-statutory 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. On March 23, 2023, the Company filed a Registration Statement on Form S-8 which registered 500,000 shares available for issuance under the Inducement Plan, all of which became available for grant and issuance under the Inducement Plan on February 17, 2023.

As of March 31, 2023, a total of 585,668 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 and comprehensive loss for stock-based compensation arrangements during any of the periods presented.

Stock-based compensation expense was recognized in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Research and development	$	182	$	160
General and administrative		449		484
Total	$	631	$	644

Stock Options

The Company granted options to purchase 240,000 and 108,517 shares of the Company’s common stock during the three months ended March 31, 2023 and 2022, respectively. There were no performance-based options granted during the three months ended March 31, 2023 and 2022, respectively. 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,
	2023	2022
Expected life (years)	6.0	6.0
Risk-free interest rate	3.5%-4.0%	1.7%
Volatility	98%-99%	88%
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, 2023 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, 2023		686,574		$	28.83		7.93
Options granted		240,000			2.37
Options exercised		—			—
Options canceled/forfeited		(249	)		2.80
Balance at March 31, 2023		926,325		$	21.98		8.21	$	—
Options exercisable at March 31, 2023		428,551		$	34.46		7.30	$	—
Options vested and expected to vest at March 31, 2023		903,367		$	20.61		8.28	$	—

The weighted-average grant date fair value of options granted was $1.88 and $3.75 per share for the three months ended March 31, 2023 and 2022, respectively. At March 31, 2023 total unrecognized employee stock-based compensation related to stock options that are likely to vest was $3.2 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.7 years.

Restricted Stock Units

There were zero and 8,965 restricted stock units granted by the Company during the three months ended March 31, 2023 and 2022, 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, 2023 as issued under the 2014 Plan:


	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at January 1, 2023		19,068		$	57.75
Restricted stock units granted		-		$	0.00
Restricted stock units vested		(9,534	)	$	57.75
Restricted stock units canceled/forfeited		-		$	0.00
Outstanding at March 31, 2023		9,534		$	57.75

The weighted-average grant-date fair value of all restricted stock units granted during the three months ended March 31, 2023 and 2022 was zero and $5.40, respectively. The fair value of all restricted stock units vested during the three months ended March 31, 2023 and 2022 was $23,000 and $0.1 million, respectively. At March 31, 2023, total unrecognized employee stock-based compensation related to restricted stock units was $0.4 million, which is expected to be recognized over the weighted-average remaining vesting period of 0.8 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 1,864 shares of the Company’s common stock has been made available for sale under the ESPP. In addition, the ESPP provides for annual increases in the number of shares available for issuance under the plan on the first day of each year beginning in the year following the initial date that the board of directors authorizes commencement, equal to the least of:

•

1.0% of the outstanding shares of the Company’s common stock on the first day of such year;

•

3,729 shares; or

•

such amount as determined by the board of directors.

As of March 31, 2023, there were no purchases by employees under this plan.

Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2023

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, 2023
	Total		Level 1		Level 2		Level 3
Liabilities
2018 PIPE warrant liability	$	1	$	—	$	—	$	1
Essentialis purchase price contingency liability		9,134		—		—		9,134
Total common stock warrant and contingent consideration liability	$	9,135	$	—	$	—	$	9,135


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Liabilities
2018 PIPE warrant liability	$	1	$	—	$	—	$	1
Essentialis purchase price contingency liability		8,835		—		—		8,835
Total common stock warrant and contingent consideration liability	$	8,836	$	—	$	—	$	8,836

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, 2023 and 2022 (dollars in thousands):


	2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Contingent Liability
Balance at January 1, 2023		34,241	$	1		$	8,835
Change in value of 2018 PIPE Warrants		—		—			—
Change in value of contingent liability		—		—			299
Balance at March 31, 2023		34,241	$	1		$	9,134

	2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Contingent Liability
Balance at January 1, 2022		34,241	$	31		$	9,547
Change in value of 2018 PIPE Warrants		—		(27	)		—
Change in value of contingent liability		—		—			(858	)
Balance at March 31, 2022		34,241	$	4		$	8,689

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	8,168,788	8,159,382
Common stock, shares outstanding	8,168,788	8,159,382

Stockholders' Equity - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		12 Months Ended
	Dec. 16, 2022	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Feb. 17, 2023	Jan. 01, 2023	Aug. 26, 2022	Jul. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value per option granted (in dollars per share)			$ 1.88	$ 3.75
Number of shares available for issuance under the plan on the first day of each year			8,168,788		8,159,382
Convertible preferred stock, shares authorized			10,000,000		10,000,000			10,000,000
Tranche A [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	8,598,870
Warrants and rights immediately exercisable term	30 days
Warrants expire term prior to anniversary date of issuance	3 years 6 months
Exercise price of warrants (in dollars per share)	$ 1.75
Exercisable warrants maximum aggregate exercise price	$ 15,000,000.0
Tranche B [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)	14,000,000
Warrants expire term prior to anniversary date of issuance	3 years 6 months
Warrants and rights exercisable term from following receipt of U.S. Food and drug administration approval	30 days
Exercise price of warrants (in dollars per share)	$ 2.50
Exercisable warrants maximum aggregate exercise price	$ 35,000,000.0
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			585,668			500,000
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			240,000	108,517
Future stock-based compensation for unvested employee options granted and outstanding			$ 3,200,000
Future stock-based compensation, requisite service period			2 years 8 months 12 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			15,508				238,329
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
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
Unrecognized stock based compensation expense			$ 400,000
Stock units granted			0	8,965
Vesting percentage			100.00%
Fair value of restricted stock units vested			$ 23,000,000	$ 100,000
Weighted average grant-date fair value of all restricted stock units granted			$ 0	$ 5.40
Weighted average remaining vesting period			9 months 18 days
Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant-date fair value of all restricted stock units granted			$ 0.00
Warrants to Purchase Stock [Member] \| 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants outstanding (in shares)			6,804
Exercise price of warrants (in dollars per share)			$ 365.25
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)			1,100
Exercise price of warrants (in dollars per share)			$ 535.50
Warrants term			10 years
Warrants expiration period			2024-11
Controlled Equity Offering Sales Agreement [Member] \| Cantor [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (shares)			104,773
Common stock, maximum aggregate purchase price									$ 25,000,000.0
Net proceeds from sale of common stock			$ 300,000
Securities Purchase Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock purchased upon issuance of warrants	22,598,870
Exercise price of warrants (in dollars per share)	$ 0.4425
Underwritten Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (shares)		2,666,667
Price per unit		$ 3.75		$ 3.75
Number of common stock purchased upon issuance of warrants		1,333,333		1,333,333
Public offering price per pre-funded warrant		$ 3.60		$ 3.60
Per share exercise price for pre-funded warrant		$ 0.15		$ 0.15
Measurement term		5 years		5 years
Proceeds from offering after deducting underwriting discount and other estimated offering expenses		$ 13,800,000
Exercise price of warrants (in dollars per share)		$ 4.50		$ 4.50
Underwritten Public Offering [Member] \| Securities Purchase Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Net proceeds from sale of common stock					$ 60,000,000.0
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant			1,864
Percentage of outstanding stock maximum			1.00%
Number of shares available for issuance under the plan on the first day of each year			3,729
Number of shares purchases by employees			0

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	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

Warrants (Tables)

3 Months Ended

Mar. 31, 2023

Warrants and Rights Note Disclosure [Abstract]

Fair Value of Convertible Preferred Stock Warrant Liability

The following summarizes certain key assumptions used in estimating the fair value:


	March 31, 2023			December 31, 2022
Volatility		125	%		117	%
Contractual term (years)		0.7			1.0
Expected dividend yield		—	%		—	%
Risk-free rate		5.02	%		4.74	%

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2023

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, 2023
	Total		Level 1		Level 2		Level 3
Liabilities
2018 PIPE warrant liability	$	1	$	—	$	—	$	1
Essentialis purchase price contingency liability		9,134		—		—		9,134
Total common stock warrant and contingent consideration liability	$	9,135	$	—	$	—	$	9,135


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Liabilities
2018 PIPE warrant liability	$	1	$	—	$	—	$	1
Essentialis purchase price contingency liability		8,835		—		—		8,835
Total common stock warrant and contingent consideration liability	$	8,836	$	—	$	—	$	8,836

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 is obligated to make cash earnout payments of up to a maximum of $21.2 million to the former Essentialis stockholders. 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 U.S. Food and Drug Administration (FDA) as well as reaching cumulative revenue milestones. The Level 3 estimates are based, in part, on subjective assumptions. In determining the likelihood of this occurring, the analysis relied on published research relating to clinical development success rates. Based on management’s assessment, a 72% probability of achieving each milestone was determined to be reasonable as of each of March 31, 2023 and December 31, 2022. During the periods presented, the Company has not changed the manner in which it values its Essentialis purchase price contingent liability.

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, 2023 and 2022 (dollars in thousands):


	2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Contingent Liability
Balance at January 1, 2023		34,241	$	1		$	8,835
Change in value of 2018 PIPE Warrants		—		—			—
Change in value of contingent liability		—		—			299
Balance at March 31, 2023		34,241	$	1		$	9,134

	2018 PIPE Warrants					Purchase Price
	Number of Warrants		Liability			Contingent Liability
Balance at January 1, 2022		34,241	$	31		$	9,547
Change in value of 2018 PIPE Warrants		—		(27	)		—
Change in value of contingent liability		—		—			(858	)
Balance at March 31, 2022		34,241	$	4		$	8,689

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Schedule of Weighted-Average Common Shares Outstanding

The following securities are the weighted-average common shares outstanding used to calculate basic and diluted net loss per common share:


	As of March 31,
	2023		2022
Common stock		8,166,385		5,334,712
2022 pre-funded warrants		1,280,965		-
Total		9,447,350		5,334,712

Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding


	As of March 31,
	2023		2022
Warrants issued to 2010/2012 convertible note holders to purchase common stock		6,804		6,804
Options to purchase common stock		926,325		516,445
Outstanding restricted stock units		9,534		19,233
Warrants issued to underwriter to purchase common stock		1,100		1,100
2018 PIPE warrants		34,241		34,241
2022 common warrants		4,000,000		4,000,000
Total		4,978,004		4,577,823

Commitments and Contingencies - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 81	$ 81
Short-term lease cost	10	5
Total operating lease cost	$ 91	$ 86

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	6 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]
Risk-free interest rate	3.50%
Volatility	98.00%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	4.00%
Volatility	99.00%

Net Loss per Share - Schedule of Weighted-Average Common Shares Outstanding (Detail) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	9,447,350	5,334,712
Weighted-average common shares outstanding used to calculate diluted shares	9,447,350	5,334,712
Common Stock [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	8,166,385	5,334,712
Weighted-average common shares outstanding used to calculate diluted shares	8,166,385	5,334,712
2022 Pre-funded Warrants [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	1,280,965
Weighted-average common shares outstanding used to calculate diluted shares	1,280,965

Warrants

3 Months Ended

Mar. 31, 2023

Text Block [Abstract]

Warrants

Note 5. Warrants

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 34,241 shares of the Company’s common stock at an exercise price equal to $30.00 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 $30.00.

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 and comprehensive loss.

As of March 31, 2023 and December 31, 2022, the fair value of the 2018 PIPE Warrants was estimated at approximately $1,000.

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, 2023			December 31, 2022
Volatility		125	%		117	%
Contractual term (years)		0.7			1.0
Expected dividend yield		—	%		—	%
Risk-free rate		5.02	%		4.74	%

The Black-Scholes pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates:

•

Volatility: The Company calculated the estimated volatility rate based on 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.

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, 2023	Mar. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	4,978,004	4,577,823
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	6,804	6,804
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	926,325	516,445
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	9,534	19,233
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	1,100	1,100
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	34,241	34,241
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	4,000,000	4,000,000

Going Concern and Management's Plans

3 Months Ended

Mar. 31, 2023

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 $8.4 million during the three months ended March 31, 2023 and has an accumulated deficit of $245.8 million at March 31, 2023 resulting from having incurred losses since its inception. The Company had $7.9 million of cash and cash equivalents on hand at March 31, 2023 and used $6.7 million of cash in its operating activities during the three months ended March 31, 2023.

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. In December 2022, the Company entered into a Securities Purchase Agreement for up to $60.0 million in additional funding if certain conditions are met. We completed the closing of the sale and issuance of the warrants for $10.0 million in May 2023. The receipt of up to $50.0 million is contingent upon the exercise of the warrants and the future performance of the Company. As the remaining funds are contingent, under accounting principles generally accepted in the United States of America (GAAP), management is not able to consider them available when assessing the Company's ability to operate as a going concern. 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. However, access to such capital resources is uncertain and 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.

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, 2023	Mar. 31, 2022
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 8,835	$ 9,547
Change in value of liabilities	299	(858)
Balance at end of period	9,134	8,689
2018 PIPE Warrant Liability [Member] \| Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 1	$ 31
Balance at the beginning of period, in shares	34,241	34,241
Change in value of liabilities		$ (27)
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Fair Value Adjustment Of Warrants	Fair Value Adjustment Of Warrants
Balance at end of period	$ 1	$ 4
Balance at the end of period, in shares	34,241	34,241

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2023

Commitments And Contingencies Disclosure [Abstract]

Schedule of Components of Lease Expense

The components of lease expense during the three months ended March 31, 2023 and 2022 were as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Operating lease cost:
Operating lease cost	$	81	$	81
Short-term lease cost		10		5
Total operating lease cost	$	91	$	86