0000950170-24-027500 | 10-K | XBRL Viewer

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

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Public Offering [Member]	Common Stock [Member]	Common Stock [Member] Public Offering [Member]	Paid-In Capital [Member]	Paid-In Capital [Member] Public Offering [Member]	Accumulated Deficit [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	2,530				2,530
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 and issuance of common stock warrants and pre-funded common stock warrants, net of issuance costs	342	$ 9,327		$ 3	342	$ 9,324
Sale of common stock and issuance of common stock warrants and pre-funded common stock warrants, net of issuance costs (shares)			104,773	2,666,667
Sale of pre-funded warrants in public offering, net of issuance costs	4,439				4,439
Exercise of common stock warrants (shares)			48,688
Net loss	(24,067)						(24,067)
Balances at ending at Dec. 31, 2022	10,348		$ 8		247,762		(237,422)
Balances at end (shares) at Dec. 31, 2022			8,159,382
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	5,809				5,809
Issuance of restricted stock units under equity incentive plan	136				136
Issuance of restricted stock units under equity incentive plan (shares)			423,248
Tax withholding payments for net share-settled equity awards (shares)			(128)
Sale of common stock and issuance of common stock warrants and pre-funded common stock warrants, net of issuance costs	137,857		$ 6		137,851
Sale of common stock and issuance of common stock warrants and pre-funded common stock warrants, net of issuance costs (shares)			7,047,397
Exercise of common stock warrants	41,998		$ 17		41,981
Exercise of common stock warrants (shares)			15,961,267
Exercise of stock options	347		$ 1		346
Exercise of stock options (shares)			86,993
Net loss	(38,988)						(38,988)
Balances at ending at Dec. 31, 2023	$ 157,507		$ 32		$ 433,885		$ (276,410)
Balances at end (shares) at Dec. 31, 2023			31,678,159

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

Note 7. Leases

Facility Leases

The Company's operating lease for its headquarters facility office space in Redwood City, California began in June 2021 and expired in May 2023. In April 2023, the Company entered into a twenty-four month lease extension commencing on June 1, 2023. The term of the lease extension expires in May 2025.

The Company’s operating lease ROU assets, current operating lease liabilities and long-term operating lease liabilities each appear as a separate line within the Company’s consolidated balance sheet. As of December 31, 2023 and December 31, 2022, the Company’s short-term liabilities were equal to $0.3 million and $0.2 million, respectively, and the long-term operating lease liabilities were equal to $0.1 million as of December 31, 2023. There were no long-term operating lease liabilities as of December 31, 2022.

The Company recorded an increase to its right-of-use asset by $0.6 million and an increase to its lease liability by $0.6 million as a result of the lease extension. The weighted average discount rate related to the Company’s lease liabilities was 8.25% as of December 31, 2023 over a remaining term of 17 months, and 9% as of December 31, 2022 over the remaining term of 5 months. The discount rates were determined based on estimates of the Company's incremental borrowing rate, as the discount rates implicit in the Company’s leases cannot be readily determined.

The components of lease expense were as follows (in thousands):


	Year Ended
	December 31, 2023		December 31, 2022
Operating lease cost:
Operating lease cost	$	312	$	324
Short-term lease cost		44		29
Total operating lease cost	$	356	$	353

Supplemental cash flow information related to leases was as follows (in thousands):


	Year Ended
	December 31, 2023		December 31, 2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	341	$	354

The following is a schedule by year of future maturities of the Company’s operating lease liabilities as of December 31, 2023 (in thousands):


2024		287
2025		143
Total lease payments		430
Less interest		(27	)
Total	$	403

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Mar. 07, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Milestones payment	$ 100.0	$ 200.0
Percentage of probability of achieving milestone	88.00%	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

Stockholders' Equity - Summary of Outstanding Common Stock Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 19, 2018
Class of Warrant or Right [Line Items]
Number of Common Shares	13,071,883	5,323,110
Common Stock Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	7,904	7,904
Weighted Average Exercise Price per Share	$ 388.94	$ 388.94
Expiration Date	2024-11
2018 PIPE Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	12,452	34,241
Weighted Average Exercise Price per Share		$ 30	$ 30
Expiration Date	2023-12
March 2022 Common Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	1,929,066	4,000,000
Weighted Average Exercise Price per Share	$ 4.5	$ 4.5
Expiration Date	2027-03
March 2022 Pre-funded Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares		1,280,965
Weighted Average Exercise Price per Share		$ 0.15
Expiration Date	2027-03
May 2023 Tranche A Pre-funded Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	2,758,281
Weighted Average Exercise Price per Share	$ 0.01
Expiration Date	2026-11
May 2023 Tranche B Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	6,750,000
Weighted Average Exercise Price per Share	$ 2.5
Expiration Date	2026-11
May 2023 Tranche B Pre-funded Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	451,632
Weighted Average Exercise Price per Share	$ 0.01
Expiration Date	2026-11
October 2023 Pre-funded Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Shares	1,175,000
Weighted Average Exercise Price per Share	$ 0.01

Income Taxes - Provision for Income Tax Benefit by Applying Statutory Federal Income Tax Rate to Operating Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax (benefit) on the loss before income tax expense computed at the federal statutory rate	$ (8,187)	$ (5,055)
State tax (benefit) at statutory rate, net of federal benefit	(505)	(527)
Foreign rate differential	6
Change in valuation allowance	8,934	5,702
Change in research and development credits	(1,631)	(652)
Stock based compensation	(600)	(734)
Change in fair value of warrants	38	(6)
Change in fair value of contingent consideration	570	(150)
Section 162(m) limitation	589
Change in net operating loss true up	39	739
Change in capital losses		405
Change in state rates	653	375
Other	$ 94	$ (97)

Net Loss per Share - Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	11,072,169	4,747,787
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	2,369,665	686,574
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	15,534	19,068
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
March 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	1,929,066	4,000,000
May 2023 Tranche B Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	6,750,000

Other Financial Statement Details - Future Amortization Expense (Detail) - Patents And Trademark [Member] $ in Thousands	Dec. 31, 2023 USD ($)
Finite Lived Intangible Assets [Line Items]
2024	$ 1,944
2025	1,944
2026	1,944
2027	1,944
2028 and thereafter	973
Net Amount	$ 8,749

Subsequent Events - Additional Information (Detail) - Redwood City, California [Member] - ft²	Feb. 08, 2024	Dec. 31, 2023
Subsequent Event [Line Items]
Operating lease, term of contract		24 months
Subsequent Event [Member]
Subsequent Event [Line Items]
Operating lease, term of contract	6 months
Area of operating lease	4,141
Operating lease, expiration date	Oct. 31, 2024

Income Taxes - Summary of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 1,936	$ 1,557
Increase related to current year tax positions	1,002	379
Ending balance	$ 2,938	$ 1,936

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 8. Commitments and 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 - Additional Information (Detail) - USD ($)				1 Months Ended		12 Months Ended
	Oct. 02, 2023	Sep. 26, 2023	Dec. 16, 2022	Oct. 31, 2023	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	May 25, 2023	Mar. 23, 2023	Feb. 17, 2023	Aug. 26, 2022	Jul. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Convertible preferred stock, shares authorized						10,000,000	10,000,000				10,000,000
Number of Common Warrant Shares						13,071,883	5,323,110
Public offering price per pre-funded warrant	$ 19.99
Proceeds from issuance or sale of equity	$ 129,000,000					$ 129,000,000
Offering costs				$ 8,200,000
Stock-based compensation expense						$ 5,945,000	$ 2,530,000
Expected dividend yield						0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)						$ 5.04	$ 2.62
Number of shares available for issuance under the plan on the first day of each year						31,678,159	8,159,382
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						445,668				500,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Income tax benefits recognized from stock-based compensation						$ 1,900,000	$ 0
Number of options granted						1,821,784	283,919
Expected dividend yield						0.00%
Future stock-based compensation for unvested employee options granted and outstanding						$ 9,100,000
Future stock-based compensation, requisite service period						2 years 6 months
Stock Options [Member] \| 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant						1,465		1,800,000	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]
Unrecognized stock based compensation expense						$ 200,000
Stock units granted						420,710	8,965
Shares granted to date						414,710
Vesting percentage							100.00%
Fair value of restricted stock units vested						$ 12,000,000	$ 100,000
Weighted average grant-date fair value of all restricted stock units granted						$ 5.49	$ 5.33
Weighted average remaining vesting period						2 months 12 days
Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units granted						420,710	8,965
Weighted average grant-date fair value of all restricted stock units granted						$ 5.49	$ 5.33
Warrants to Purchase Stock [Member] \| 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Common Warrant Shares						6,804
Weighted Average Exercise Price per Share						$ 365.25
Expiration period						2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Common Warrant Shares						1,100
Weighted Average Exercise Price per Share						$ 535.5
Warrants term						10 years
Expiration period						2024-11
March 2022 Common Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Common Warrant Shares						1,929,066	4,000,000
Weighted Average Exercise Price per Share						$ 4.5	$ 4.5
Expiration period						2027-03
Controlled Equity Offering Sales Agreement [Member] \| Cantor [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (shares)						1,877,170
Common stock, maximum aggregate purchase price												$ 25,000,000
Net proceeds from sale of common stock						$ 7,400,000
Securities Purchase Agreement [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale and issuance of warrants to purchase common stock						10,000,000
Number of common stock purchased upon issuance of warrants			22,598,870
Weighted Average Exercise Price per Share			$ 0.4425
Proceeds from sale of common stock and pre-funded warrants	$ 60,000,000
Shares issued from sale of common stock	1,825,000
Shares issued from sale of pre-funded warrants	1,175,000
Tranche A [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Common Warrant Shares			8,598,870
Warrants and rights immediately exercisable term			30 days
Proceeds from warrant exercise						15,000,000
Sale and issuance of warrants to purchase common stock		$ 15,000,000
Weighted Average Exercise Price per Share			$ 1.75
Exercisable warrants maximum aggregate exercise price			$ 15,000,000
Tranche B [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Common Warrant 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
Proceeds from warrant exercise						18,100,000
Contingent receipt upon exerise of warrants and future performance of company						16,900,000
Weighted Average Exercise Price per Share			$ 2.5
Exercisable warrants maximum aggregate exercise price			$ 35,000,000
Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Price per unit	$ 20
Underwritten Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock (shares)	3,450,000				2,666,667
Price per unit	$ 20				$ 3.75
Proceeds from warrant exercise						$ 0
Warrants exercised						1,280,965
Number of common stock purchased upon issuance of warrants					1,333,333
Public offering price per pre-funded warrant					$ 3.6
Per share exercise price for pre-funded warrant					$ 0.15
Measurement term					5 years
Weighted Average Exercise Price per Share					$ 4.5
Proceeds from offering after deducting underwriting discount and other estimated offering expenses	$ 69,000,000				$ 13,800,000
Underwritten Public Offering [Member] \| March 2022 Common Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from warrant exercise						$ 9,300,000
Warrants exercised						2,070,934
Underwritten Public Offering [Member] \| Securities Purchase Agreement [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Net proceeds from sale of common stock							$ 60,000,000
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 (Tables)

12 Months Ended

Dec. 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 December 31, 2023
	Total		Level 1		Level 2		Level 3
Liabilities
Essentialis purchase price contingency liability	$	11,549	$	-	$	-	$	11,549


	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 assets and liabilities (dollars in thousands):


	2018 PIPE Warrants						Purchase Price
	Number of						Contingent
	Warrants			Liability			Liability
Balance at December 31, 2021		34,241		$	31		$	9,547
Change in value of 2018 PIPE Warrants		—			(30	)		-
Change in value of contingent liability		—			—			(712	)
Balance at December 31, 2022		34,241		$	1		$	8,835
Change in value of 2018 PIPE Warrants		—			419			—
Exercise of 2018 PIPE Warrants		(21,789	)		(183	)		—
Expiration of 2018 PIPE Warrants		(12,452	)		(237	)		—
Change in value of contingent liability		—			—			2,714
Balance at December 31, 2023		0		$	-		$	11,549

Overview

12 Months Ended

Dec. 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 DCCR (Diazoxide Choline) 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.

Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Non-current deferred tax assets:
Federal and state net operating loss carryforwards	$ 51,481	$ 49,024
Research and other credits	6,352	4,146
Capitalized research and development	6,778	2,828
Reserves and accruals	655	547
Fixed assets	29	44
Capital loss carryover	432	555
Stock based compensation	2,013	2,682
Lease liability	85	42
Other deferred tax assets	54	72
Gross non-current deferred tax assets	67,879	59,940
Intangible assets	(1,837)	(2,888)
Right-of-use assets	(86)	(35)
Total non-current deferred tax liabilities	(1,923)	(2,923)
Total deferred tax assets	65,956	57,017
Valuation allowance	$ (65,956)	$ (57,017)

Other Financial Statement Details - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 101	$ 101
Less accumulated depreciation and amortization	(89)	(75)
Total	12	26
Computer Hardware [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	72	72
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 29	$ 29

Liquidity

12 Months Ended

Dec. 31, 2023

Cash and Cash Equivalents [Abstract]

Liquidity

Note 2. Liquidity

The Company had a net loss of $39.0 million during 2023 and has an accumulated deficit of $276.4 million at December 31, 2023 resulting from having incurred losses since its inception. The Company had $169.7 million of cash and cash equivalents on hand at December 31, 2023 and used $24.9 million of cash in its operating activities during 2023.

The Company has financed its operations principally through issuance of equity securities. On October 2, 2023, the Company closed a public and concurrent private financing with gross proceeds of $129.0 million.

In December 2022, the Company entered into a Securities Purchase Agreement providing for the sale of up to $60.0 million in warrants (Tranche A and Tranche B) and the common stock issuable upon the exercise thereof. The Company completed the closing of the sale and issued both tranches of warrants for $10.0 million in May 2023. The announcement of positive top-line data from the randomized withdrawal period of Study C602 triggered the mandatory exercise of the Tranche A warrants, and as of December 31, 2023, the Company had received $15.0 million. Certain investors exercised their Tranche B warrants and the Company has received $18.1 million as of December 31, 2023. The receipt of the exercise price of the remaining Tranche B warrants for up to $16.9 million is contingent upon the exercise of such warrants. The Company also received $9.3 million in gross proceeds from the exercise of certain March 2022 warrants during 2023.

The Company expects to continue incurring losses for the foreseeable future. However, the Company expects that its current cash and cash equivalents balances will be sufficient to enable the Company to meet its obligations for at least the next twelve months from the date of this filing.

Fair Value of Financial Instruments

12 Months Ended

Dec. 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 December 31, 2023
	Total		Level 1		Level 2		Level 3
Liabilities
Essentialis purchase price contingency liability	$	11,549	$	-	$	-	$	11,549


	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. The 2018 PIPE Warrants expired on December 21, 2023.

Based on the terms of the 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 FDA as well as achieving two commercial sales milestones of $100 million and $200 million in cumulative revenue. 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, an 88% and a 72% probability of achieving all three milestones was determined to be reasonable as of December 31, 2023 and December 31, 2022, respectively. 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 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 assets and liabilities (dollars in thousands):


	2018 PIPE Warrants						Purchase Price
	Number of						Contingent
	Warrants			Liability			Liability
Balance at December 31, 2021		34,241		$	31		$	9,547
Change in value of 2018 PIPE Warrants		—			(30	)		-
Change in value of contingent liability		—			—			(712	)
Balance at December 31, 2022		34,241		$	1		$	8,835
Change in value of 2018 PIPE Warrants		—			419			—
Exercise of 2018 PIPE Warrants		(21,789	)		(183	)		—
Expiration of 2018 PIPE Warrants		(12,452	)		(237	)		—
Change in value of contingent liability		—			—			2,714
Balance at December 31, 2023		0		$	-		$	11,549

- 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

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Summary of Outstanding Common Stock Warrants

As of December 31, 2023 and December 31, 2022, the following table summarizes the Company's outstanding common stock warrants:


	As of December 31, 2023				As of December 31, 2022
	Number of Common Warrant Shares		Weighted Average Exercise Price per Share		Number of Common Warrant Shares		Weighted Average Exercise Price per Share		Expiration Date
Common stock warrants		7,904	$	388.94		7,904	$	388.94	November 2024
2018 PIPE warrants		—	$	-		34,241	$	30.00	December 2023
March 2022 Common warrants		1,929,066	$	4.50		4,000,000	$	4.50	March 2027
March 2022 Pre-funded warrants		—	$	-		1,280,965	$	0.15	March 2027
May 2023 Tranche A Pre-funded warrants		2,758,281	$	0.01		—	$	—	November 2026
May 2023 Tranche B warrants		6,750,000	$	2.50		—	$	—	November 2026 (1)
May 2023 Tranche B Pre-funded warrants		451,632	$	0.01		—	$	—	November 2026
October 2023 Pre-funded warrants		1,175,000	$	0.01		—	$	—	N/A
Total		13,071,883				5,323,110

(1) Subject to earlier expiration as described above.

Summary of Stock Based Compensation Expense

Stock compensation expense was recognized in the consolidated statements of operations as follows (in thousands):


	Year ended
	December 31, 2023		December 31, 2022
Research and development	$	2,434	$	692
General and administrative		3,511		1,838
Total	$	5,945	$	2,530

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:


	Year Ended
	December 31, 2023	December 31, 2022
Expected life (years)	5.3-6.1	5.5-6.0
Risk-free interest rate	3.5%-4.5%	1.7%-3.1%
Volatility	98%-122%	88%-95%
Dividend rate	— %	— %

Summary of Stock Option and Restricted Stock Unit Transactions

The following table summarizes stock option transactions for the years ended December 31, 2023 and 2022 as issued under the 2014 Plan and the Inducement Plan:


	Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	Outstanding			Share		(in years)		(in thousands)
Balance at December 31, 2021		408,329		$	46.28		7.94
Options granted		283,919			3.56
Options canceled/forfeited		(5,674	)		19.31
Balance at December 31, 2022		686,574		$	28.83		7.93
Options granted		1,821,784			6.18
Options exercised		(89,993	)		4.01
Options canceled/forfeited		(48,700	)		67.84
Balance at December 31, 2023		2,369,665		$	11.56		8.72	$	70,834
Options exercisable at December 31, 2023		797,988		$	18.31		7.76	$	20,320
Options vested and expected to vest at December 31, 2023		2,346,707		$	11.34		8.75	$	70,834

Summary of Restricted Stock Unit Transactions

The following table summarizes restricted stock unit transactions for the years ended December 31, 2023 and 2022 as issued under the 2014 Plan:


	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at December 31, 2021		29,050		$	57.75
Restricted stock units granted		8,965			5.33
Restricted stock units vested		(18,646	)		32.55
Restricted stock units cancelled/forfeited		(301	)		57.85
Outstanding at December 31, 2022		19,068		$	57.75
Restricted stock units granted		420,710			5.49
Restricted stock units vested		(423,248	)		6.43
Restricted stock units cancelled/forfeited		(996	)		5.25
Outstanding at December 31, 2023		15,534		$	43.92

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 3 Financial Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares	5,323,110
Balance at the end of period, in shares	13,071,883	5,323,110
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	2,714	(712)
Balance at end of period	$ 11,549	$ 8,835
2018 PIPE Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares	34,241
Exercise of warrants, shares	21,789
Balance at the end of period, in shares	12,452	34,241
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	$ 419	$ (30)
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
Exercise of warrants, shares	(21,789)
Exercise of warrants	$ (183)
Expiration of warrants, in shares	(12,452)
Expiration of warrants	$ (237)
Balance at end of period	$ 0	$ 1
Balance at the end of period, in shares	0	34,241

Leases - Schedule of Future Maturities (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 287
2025	143
Total lease payments	430
Less interest	(27)
Total	$ 403

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

Note 10. Income Taxes

The geographical distribution of loss before income taxes are summarized below (in thousands):


	December 31,
	2023			2022
United States	$	(39,180	)	$	(24,173	)
Foreign		192			106
Loss before income taxes	$	(38,988	)	$	(24,067	)

The provision for income tax benefit differs from the amount estimated by applying the statutory federal income tax rate to the operating loss due to the following (in thousands):


	December 31,
	2023			2022
Tax (benefit) on the loss before income tax expense computed at the federal statutory rate	$	(8,187	)	$	(5,055	)
State tax (benefit) at statutory rate, net of federal benefit		(505	)		(527	)
Foreign rate differential		6			-
Change in valuation allowance		8,934			5,702
Change in research and development credits		(1,631	)		(652	)
Stock based compensation		(600	)		(734	)
Change in fair value of warrants		38			(6	)
Change in fair value of contingent consideration		570			(150	)
Section 162(m) limitation		589			-
Change in net operating loss true up		39			739
Change in capital losses		—			405
Change in state rates		653			375
Other		94			(97	)
Provision for income tax benefit	$	—		$	—

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities are as follows at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023			2022
Non-current deferred tax assets:
Federal and state net operating loss carryforwards	$	51,481		$	49,024
Research and other credits		6,352			4,146
Capitalized research and development		6,778			2,828
Reserves and accruals		655			547
Fixed assets		29			44
Capital loss carryover		432			555
Stock based compensation		2,013			2,682
Lease liability		85			42
Other deferred tax assets		54			72
Gross non-current deferred tax assets		67,879			59,940
Intangible assets		(1,837	)		(2,888	)
Right-of-use assets		(86	)		(35	)
Total non-current deferred tax liabilities		(1,923	)		(2,923	)
Total deferred tax assets		65,956			57,017
Valuation allowance		(65,956	)		(57,017	)
Net deferred tax assets	$	—		$	—

The Company has recorded a full valuation allowance against its net deferred tax assets due to the uncertainty as to whether such assets will be realized. The valuation allowance increased by $8.9 million from December 31, 2022 to December 31, 2023 primarily due to the generation of current year net operating losses, research and development credits claimed, capitalized research and developments costs, and stock-based compensation.

As of December 31, 2023, the Company had $206.7 million of federal, $111.0 million of state and $2.3 million of foreign net operating losses available to offset future taxable income. The Federal net operating loss carryforwards arising from years prior to 2018 began to expire in 2022, however post 2017 federal net operating loss

carryforwards of $93.1 million may be carried forward indefinitely. The state net operating loss carryforwards will begin to expire in 2028 and the foreign net operating loss carryforward can be carried forward indefinitely, if not utilized. As of December 31, 2023, the Company also had $6.4 million of federal and $3.4 million of state research and development credit carryforwards. The federal research and development credit carryforward begin to expire in 2024 and the state research and development credit can be carried forward indefinitely. Beginning in fiscal year 2023, the Tax Cuts and Jobs Act of 2017 eliminates the option to deduct research and development expenditures currently and requires taxpayers to amortize such costs over a period of five or fifteen years. While it is possible that Congress may modify, defer, or repeal such provision, we have no assurance that the provision will be modified, deferred or repealed.

Utilization of the net operating loss and tax credit carry forwards are subject to an annual limitation due to the ownership percentage change limitations provided by the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss before utilization. The Company completed Section 382 analysis through December 2016 and determined that an ownership change, as defined under Section 382 of the Internal Revenue Code, occurred in June 2016. The Company’s tax attributes are subject to an annual limitation of $0.5 million per year for federal purposes. For years ended after December 31, 2016, the utilization of net operating losses and tax credit carryforwards are subject to further limitation in the event an additional ownership change were to occur for tax purposes. The Company is currently in the process of analyzing whether there was an ownership change, as defined under Section 382 of the Internal Revenue Code, resulting from the issuance of new shares during 2018 through 2023 and expects that analysis to completed during 2024. As such, as of the date of these consolidated financial statements the Company is not able to determine the impact on the net operating loss (NOL) carryforwards, if any.

U.S. taxes and foreign withholding taxes have not been provided on undistributed earnings for certain non-U.S. subsidiaries as of December 31, 2023, as the earnings, if any, are intended to be indefinitely reinvested.

The following tables summarize the activities of gross unrecognized tax benefits (in thousands):


	December 31,
	2023		2022
Beginning balance	$	1,936	$	1,557
Increase related to current year tax positions		1,002		379
Ending balance	$	2,938	$	1,936

The Company uses the “more likely than not” criterion for recognizing the tax benefit of uncertain tax positions and to establish measurement criteria for income tax benefits. The Company has determined it has $2.9 million of unrecognized assets and liabilities related to uncertain tax positions as of December 31, 2023. Changes in the unrecognized tax benefits within the next 12 months are expected to be similar to prior years and should not significantly increase or decrease. In the event the Company should need to recognize interest and penalties related to unrecognized tax liabilities, this amount will be recorded as a component of other expense.

There were no unrecognized tax benefits that would impact the effective tax rate as of December 31, 2023 and December 31, 2022. As of December 31, 2023, unrecognized tax benefits of $2.9 million would be offset by a change in valuation allowance.

The Company files income tax returns in the U.S. federal jurisdiction, certain state jurisdictions, United Kingdom and Ireland. In the normal course of business, the Company is subject to examination by federal, state, local and foreign jurisdictions, where applicable. In the U.S federal jurisdiction, tax years 2003 forward remain open to examination, in the state tax jurisdiction, years 2008 forward remain open to examination and in the foreign jurisdiction, years 2015 forward remain open to examination. The Company is currently not under audit by any federal, state, local or foreign jurisdiction.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 341	$ 354

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 169,681	$ 14,602
Prepaid expenses and other current assets	1,677	1,045
Total current assets	171,358	15,647
Long-term assets
Property and equipment, net	12	26
Operating lease right-of-use assets	407	131
Intangible assets, net	8,749	10,693
Other long-term assets	165
Total assets	180,691	26,497
Current liabilities
Accounts payable,net	3,149	1,777
Accrued compensation	3,135	1,675
Accrued clinical trial site costs	3,393	3,222
Operating lease liabilities	273	155
Other current liabilities	1,555	484
Total current liabilities	11,505	7,313
Long-term liabilities
Contingent liability for Essentialis purchase price	11,549	8,835
Long-term lease liabilities	130	0
Total liabilities	23,184	16,149
Commitments and contingencies (Note 8)
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, 31,678,159 and 8,159,382 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively.	32	8
Additional paid-in-capital	433,885	247,762
Accumulated deficit	(276,410)	(237,422)
Total stockholders' equity	157,507	10,348
Total liabilities and stockholders'equity	180,691	26,497
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 0	$ 1

Net Loss per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss per Share

Note 11. Net Loss per Share

Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares 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 and October 2023 and in connection with the exercise of certain May 2023 Tranche A and Tranche B warrants, 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, restricted stock units 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 and May 2023 are participating securities. However, the two-class method does not impact the net loss per share of common stock as the March 2022 and May 2023 common warrants issued do not participate in losses. For the years ended December 31, 2023 and 2022, the effect of issuing the respective 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 included in the weighted-average common shares outstanding used to calculate basic and diluted net loss per common share:


	As of December 31,
	2023		2022
Common stock		15,040,036		7,409,165
March 2022 pre-funded warrants		290,665		987,923
May 2023 Tranche A pre-funded exchange warrants		778,904		-
May 2023 Tranche B pre-funded exchange warrants		92,801		-
October 2023 pre-funded warrants		289,726		-
Total		16,492,132		8,397,088

The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares):


	As of December 31,
	2023		2022
Warrants issued to 2010/2012 convertible note holders to purchase common stock		6,804		6,804
Warrants issued to underwriter to purchase common stock		1,100		1,100
2018 PIPE warrants		-		34,241
March 2022 common warrants		1,929,066		4,000,000
May 2023 Tranche B warrants		6,750,000		-
Options to purchase common stock		2,369,665		686,574
Outstanding restricted stock units		15,534		19,068
Total		11,072,169		4,747,787

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Schedule of Components of Lease Expense

The components of lease expense were as follows (in thousands):


	Year Ended
	December 31, 2023		December 31, 2022
Operating lease cost:
Operating lease cost	$	312	$	324
Short-term lease cost		44		29
Total operating lease cost	$	356	$	353

Schedule Of Supplemental Cash Flow Information Related To Leases

Supplemental cash flow information related to leases was as follows (in thousands):


	Year Ended
	December 31, 2023		December 31, 2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	341	$	354

Operating Lease Liability Maturity

The following is a schedule by year of future maturities of the Company’s operating lease liabilities as of December 31, 2023 (in thousands):


2024		287
2025		143
Total lease payments		430
Less interest		(27	)
Total	$	403

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Less transaction costs	$ 8,449
Issuance of common stock, warrants	$ 182	$ (30)
Warrants [Member]
Less transaction costs		333
Common Stock [Member]
Less transaction costs		10
Common Stock [Member] \| Public Offering [Member]
Less transaction costs		$ 701

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses
Research and development	$ 25,189	$ 15,265
General and administrative	13,481	9,844
Change in fair value of contingent consideration	2,714	(712)
Total operating expenses	41,384	24,397
Operating loss	(41,384)	(24,397)
Other income (expense), net
Change in fair value of warrant liability	(182)	30
Interest income	2,578	300
Total other income (expense), net	2,396	330
Net loss	$ (38,988)	$ (24,067)
Net loss per common share basic	$ (2.36)	$ (2.87)
Net loss per common share diluted	$ (2.36)	$ (2.87)
Weighted-average common shares outstanding used to calculate basic net loss per common share	16,492,132	8,397,088
Weighted-average common shares outstanding used to calculate diluted net loss per common share	16,492,132	8,397,088

Other Financial Statement Details - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Other Financial Statement Details Disclosure [Abstract]
Depreciation expense	$ 14	$ 20
Amortization	$ 1,900	$ 1,900

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP), and the applicable rules and regulations of the Securities and Exchange Commission (SEC). Certain reclassifications on the consolidated statements of cash flows have been made to conform to current period presentation. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Reverse Stock Split	Reverse Stock Split On June 1, 2022, the stockholders of the Company approved a reverse stock split of its common stock at a ratio of one-for-fifteen, to be effected at the sole discretion of the Company’s Board of Directors as described in the proxy statement filed with the SEC on April 21, 2022. The implementation of the reverse stock split was approved by the Company’s Board of Directors on August 16, 2022. 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 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 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.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents at U.S. banking institutions. At December 31, 2023, the majority of the Company’s funds were invested with two separate financial institutions and at times these balances may exceed the federally-insured limits. Operating cash in excess of federally-insured limits is custodied at a separate financial institution with an overnight sweep feature into a U.S. government money market fund. As of December 31, 2022, the Company’s funds were invested in one financial institution which at times may exceed the federally insured limit.
Segments	Segments The Company operates in one segment. Management uses one measurement of profitability and does not segregate its business for internal reporting, making operating decisions, and assessing financial performance. All long-lived assets are maintained in the U.S.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments, including its money market funds, purchased with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held primarily in institutions in the U.S. and include deposits in a money market funds which were unrestricted as to withdrawal or use.
Prepaid Expenses and Other Current Assets	Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of payments primarily related to clinical trials, insurance and short-term deposits. Prepaid expenses are initially recorded upon payment and are expensed as goods or services are received.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost net of accumulated depreciation and amortization calculated using the straight-line method over the estimated useful lives of the assets, generally between three and five years. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the remaining term of the lease. Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.
Leases	Leases The Company determines whether an arrangement is a lease at inception. Specifically, it considers whether it controls the underlying asset and has the right to obtain substantially all the economic benefits or outputs from the asset. If the contractual arrangement contains a lease, the Company then determines whether it is an operating or finance lease. Right-of-Use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Lease expense for operating lease payments is recognized on a straight-line basis over the lease term. Finance lease classification results in a front-loaded expense recognition pattern over the lease term as it recognizes interest expense and amortization expense as separate components of lease expense. The Company does not separate lease components from non-lease components for all classes of underlying assets, and instead accounts for the lease and non-lease components as a single component. Variable lease payments are recognized as they are incurred and primarily include common area maintenance, utilities, real estate taxes, insurance and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company does not recognize lease assets and lease liabilities for leases with an original lease term of less than one year.
Long-Lived Assets	Long-Lived Assets The Company reviews its long-lived assets for impairment annually and whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. The Company evaluates assets for potential impairment by comparing estimated future undiscounted net cash flows to the carrying amount of the asset. If the carrying amount of the assets exceeds the estimated future undiscounted cash flows, impairment is measured based on the difference between the carrying amount and the fair value of the assets.
Intangible Assets	Intangible Assets In March 2017, the Company completed the acquisition of Essentialis in accordance with the merger agreement by and between the Company and Essentialis dated December 22, 2016 (the “Merger Agreement”). The merger transaction was accounted for as an asset acquisition under the acquisition method of accounting and accordingly, the value of $22.0 million was assigned to the identifiable intangible asset relating to the patent for DCCR, which patent expires in June 2028. Intangible assets with finite lives are amortized on a straight-line basis over their estimated useful lives, which for the patent is 11 years. The useful life of the intangible asset is evaluated each reporting period to determine whether events and circumstances warrant a revision to the remaining useful life.
Research and Development	Research and Development Research and development costs are charged to operations as incurred. Research and development costs consist primarily of salaries, benefits, bonus, share-based compensation, consultant fees, certain facility costs and other costs associated with clinical trials. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors and other vendors. Invoicing from third-party contractors for services performed can often occur several months later. The Company accrues the costs incurred for clinical trial activities as measured by patient progression and the timing of various aspects of the trial. For other services the Company accrues the costs in connection with third-party contractor activities based on its estimate of fees and costs associate with the contract that were rendered during the period and they are expensed as incurred. Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are expensed to research and development costs when incurred.
Change in Fair Value of Contingent Consideration	Change in fair value of contingent consideration The Company recorded the value of contingent future consideration to be paid for the acquisition of Essentialis as a liability in March 2017 at the date of the acquisition. The changes in value of the liability for the contingent consideration since the acquisition date are recorded as operating expense in the consolidated statements of operations.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method. Under this method, deferred income tax assets and liabilities are recorded based on the estimated future tax effects of differences between the amounts at which assets and liabilities are recorded for financial reporting purposes and the amounts recorded for income tax purposes. A valuation allowance is provided against the Company’s deferred income tax assets when their realization is not reasonably assured. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.
Common Stock Purchase Warrants and Other Derivative Financial Instruments	Common Stock Purchase Warrants and Other Derivative Financial Instruments The Company classifies common stock purchase warrants and other free standing derivative financial instruments as equity if the contracts (i) require physical settlement or net-share settlement or (ii) give the Company a choice of net-cash settlement or settlement in its own shares (physical settlement or net-share settlement). The Company classifies any contracts that (i) require net-cash settlement (including a requirement to net cash settle the contract if an event occurs and if that event is outside the control of the Company), (ii) give the counterparty a choice of net-cash settlement or settlement in shares (physical settlement or net-share settlement), or (iii) contain reset provisions as either an asset or a liability. The Company assesses classification of its freestanding derivatives at each reporting date to determine whether a change in classification between equity and liabilities is required. The Company determined that certain freestanding derivatives, which principally consist of 2018 PIPE Warrants, do not satisfy the criteria for classification as equity instruments due to the existence of certain cash settlement features that are not within the sole control of the Company or variable settlement provision that cause them to not be indexed to the Company’s own stock. The Company classified the 2018 PIPE Warrants at their fair value and re-measured them at each balance sheet date until they were exercised or expired. Any changes in the fair value were recognized as Other income (expense) in the consolidated statements of operations. The 2018 PIPE Warrants expired in December 2023.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation costs related to stock options and restricted stock units granted to employees, nonemployees and directors are measured at the date of grant based on the estimated fair value of the award. For restricted stock units this fair value is based on the Company’s common stock price on the grant date. The Company estimates the grant date fair value of stock options, and the resulting stock-based compensation expense, using the Black-Scholes option-pricing model. The grant date fair value of stock-based awards is recognized on a straight-line basis over the requisite service period, which is generally the vesting period for service-based awards. For performance-based awards the requisite service period is the longest explicit, implicit or derived service period based on management’s estimate of the probability of the performance criteria being satisfied, adjusted at each balance sheet date. The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. If the Company had made different assumptions, its stock-based compensation expense, net loss and net loss per share of common stock could have been significantly different. These assumptions include: • Expected volatility: We calculated the estimated volatility rate for stock options granted based on the volatility of our common stock for a historical period equal to the expected life of the stock options. • Expected life: Due to the lack of historical exercise history, the expected life of the Company’s service-based stock options is 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 performance-based options is 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 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. • Expected divided yield: The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Consequently, it used an expected dividend yield of zero. The Company accounts for forfeitures as they occur.
Recent Adopted Accounting Pronouncements	Recent 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 December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures, which amends the guidance in ASC 740, Income Taxes. This ASU is intended to improve the transparency of income tax disclosures by requiring (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This ASU is effective for fiscal years beginning after December 15, 2024. Adoption is permitted either prospectively or retrospectively, and the Company will adopt this ASU on a prospective basis. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures. 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.

Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 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

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP), and the applicable rules and regulations of the Securities and Exchange Commission (SEC). Certain reclassifications on the consolidated statements of cash flows have been made to conform to current period presentation.

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Reverse Stock Split

On June 1, 2022, the stockholders of the Company approved a reverse stock split of its common stock at a ratio of one-for-fifteen, to be effected at the sole discretion of the Company’s Board of Directors as described in the proxy statement filed with the SEC on April 21, 2022. The implementation of the reverse stock split was approved by the Company’s Board of Directors on August 16, 2022.

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 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 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.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents at U.S. banking institutions. At December 31, 2023, the majority of the Company’s funds were invested with two separate financial institutions and at times these balances may exceed the federally-insured limits. Operating cash in excess of federally-insured limits is custodied at a separate financial institution with an overnight sweep feature into a U.S. government money market fund. As of December 31, 2022, the Company’s funds were invested in one financial institution which at times may exceed the federally insured limit.

Segments

The Company operates in one segment. Management uses one measurement of profitability and does not segregate its business for internal reporting, making operating decisions, and assessing financial performance. All long-lived assets are maintained in the U.S.

Cash and Cash Equivalents

The Company considers all highly liquid investments, including its money market funds, purchased with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held

primarily in institutions in the U.S. and include deposits in a money market funds which were unrestricted as to withdrawal or use.

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of payments primarily related to clinical trials, insurance and short-term deposits. Prepaid expenses are initially recorded upon payment and are expensed as goods or services are received.

Property and Equipment, Net

Property and equipment are stated at cost net of accumulated depreciation and amortization calculated using the straight-line method over the estimated useful lives of the assets, generally between three and five years. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the remaining term of the lease. Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.

Leases

The Company determines whether an arrangement is a lease at inception. Specifically, it considers whether it controls the underlying asset and has the right to obtain substantially all the economic benefits or outputs from the asset. If the contractual arrangement contains a lease, the Company then determines whether it is an operating or finance lease. Right-of-Use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Lease expense for operating lease payments is recognized on a straight-line basis over the lease term. Finance lease classification results in a front-loaded expense recognition pattern over the lease term as it recognizes interest expense and amortization expense as separate components of lease expense.

The Company does not separate lease components from non-lease components for all classes of underlying assets, and instead accounts for the lease and non-lease components as a single component. Variable lease payments are recognized as they are incurred and primarily include common area maintenance, utilities, real estate taxes, insurance and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company does not recognize lease assets and lease liabilities for leases with an original lease term of less than one year.

Long-Lived Assets

The Company reviews its long-lived assets for impairment annually and whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. The Company evaluates assets for potential impairment by comparing estimated future undiscounted net cash flows to the carrying amount of the asset. If the carrying amount of the assets exceeds the estimated future undiscounted cash flows, impairment is measured based on the difference between the carrying amount and the fair value of the assets.

Intangible Assets

In March 2017, the Company completed the acquisition of Essentialis in accordance with the merger agreement by and between the Company and Essentialis dated December 22, 2016 (the “Merger Agreement”). The merger transaction was accounted for as an asset acquisition under the acquisition method of accounting and accordingly, the value of $22.0 million was assigned to the identifiable intangible asset relating to the patent for DCCR, which patent expires in June 2028.

Intangible assets with finite lives are amortized on a straight-line basis over their estimated useful lives, which for the patent is 11 years. The useful life of the intangible asset is evaluated each reporting period to determine whether events and circumstances warrant a revision to the remaining useful life.

Research and Development

Research and development costs are charged to operations as incurred. Research and development costs consist primarily of salaries, benefits, bonus, share-based compensation, consultant fees, certain facility costs and other costs associated with clinical trials. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors and other vendors. Invoicing from third-party contractors for services performed can often occur several months later. The Company accrues the costs incurred for clinical trial activities as measured by patient progression and the timing of various aspects of the trial. For other services the Company accrues the costs in connection with third-party contractor activities based on its estimate of fees and costs associate with the contract that were rendered during the period and they are expensed as incurred.

Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are expensed to research and development costs when incurred.

Change in fair value of contingent consideration

The Company recorded the value of contingent future consideration to be paid for the acquisition of Essentialis as a liability in March 2017 at the date of the acquisition. The changes in value of the liability for the contingent consideration since the acquisition date are recorded as operating expense in the consolidated statements of operations.

Income Taxes

The Company accounts for income taxes using the asset and liability method. Under this method, deferred income tax assets and liabilities are recorded based on the estimated future tax effects of differences between the amounts at which assets and liabilities are recorded for financial reporting purposes and the amounts recorded for income tax purposes. A valuation allowance is provided against the Company’s deferred income tax assets when their realization is not reasonably assured.

The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Common Stock Purchase Warrants and Other Derivative Financial Instruments

The Company classifies common stock purchase warrants and other free standing derivative financial instruments as equity if the contracts (i) require physical settlement or net-share settlement or (ii) give the Company a choice of net-cash settlement or settlement in its own shares (physical settlement or net-share settlement). The Company classifies any contracts that (i) require net-cash settlement (including a requirement to net cash settle the contract if an event occurs and if that event is outside the control of the Company), (ii) give the counterparty a choice of net-cash settlement or settlement in shares (physical settlement or net-share settlement), or (iii) contain reset provisions as either an asset or a liability. The Company assesses classification of its freestanding derivatives at each reporting date to determine whether a change in classification between equity and liabilities is required. The Company determined that certain freestanding derivatives, which principally consist of 2018 PIPE Warrants, do not satisfy the criteria for classification as equity instruments due to the existence of certain cash settlement features that are not within the sole control of the Company or variable settlement provision that cause them to not be indexed to the Company’s own stock.

The Company classified the 2018 PIPE Warrants at their fair value and re-measured them at each balance sheet date until they were exercised or expired. Any changes in the fair value were recognized as Other income (expense) in the consolidated statements of operations. The 2018 PIPE Warrants expired in December 2023.

Stock-Based Compensation

Stock-based compensation costs related to stock options and restricted stock units granted to employees, nonemployees and directors are measured at the date of grant based on the estimated fair value of the award. For restricted stock units this fair value is based on the Company’s common stock price on the grant date. The Company estimates the grant date fair value of stock options, and the resulting stock-based compensation expense, using the Black-Scholes option-pricing model. The grant date fair value of stock-based awards is recognized on a straight-line basis over the requisite service period, which is generally the vesting period for service-based awards. For performance-based awards the requisite service period is the longest explicit, implicit or derived service period based on management’s estimate of the probability of the performance criteria being satisfied, adjusted at each balance sheet date.

The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. If the Company had made different assumptions, its stock-based compensation expense, net loss and net loss per share of common stock could have been significantly different. These assumptions include:

•

Expected volatility: We calculated the estimated volatility rate for stock options granted based on the volatility of our common stock for a historical period equal to the expected life of the stock options.

•

Expected life: Due to the lack of historical exercise history, the expected life of the Company’s service-based stock options is 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 performance-based options is 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 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.

•

Expected divided yield: The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Consequently, it used an expected dividend yield of zero.

The Company accounts for forfeitures as they occur.

Recent 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 December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures, which amends the guidance in ASC 740, Income Taxes. This ASU is intended to improve the transparency of income tax disclosures by requiring (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This ASU is effective for fiscal years beginning after December 15, 2024. Adoption is permitted either prospectively or retrospectively, and the Company will adopt this ASU on a prospective basis. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures.

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.

Defined Contribution Plan

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Defined Contribution Plan

Note 12. Defined Contribution Plan

The Company sponsors a 401(k) Plan, which stipulates that eligible employees can elect to contribute to the 401(k) Plan, subject to certain limitations of eligible compensation. The Company may match employee contributions in amounts to be determined at the Company’s sole discretion. The Company made no matching contributions during the years ended December 31, 2023 and 2022.

- Definition

The entire disclosure for retirement benefits.

+ References

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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-Subparagraph (l)
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
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-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Warrants (Tables)

12 Months Ended

Dec. 31, 2023

Text Block [Abstract]

Fair Value of Convertible Preferred Stock Warrant Liability

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


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

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 5,945	$ 2,530
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,434	692
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,511	$ 1,838

Stockholders' Equity

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Stockholders' Equity

Note 9. Stockholders’ Equity

Convertible Preferred Stock

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

Public Offering of Common Stock and Concurrent Private Placement of Common Stock and Pre-Funded Warrants

On October 2, 2023, the Company closed an underwritten public offering of 3,450,000 shares of its common stock at a public offering of $20.00 per share, which included the exercise in full by the underwriters of their option to purchase additional shares. The gross proceeds of the public offering were $69.0 million, before deducting the underwriting discount and other offering expenses. Concurrently, the Company also completed the closing of approximately $60.0 million for 1,825,000 shares of its common stock and 1,175,000 pre-funded warrants in a private offering pursuant to a securities purchase agreement with certain investors, including entities affiliated with existing stockholders, at a price per share of common stock equal to the public offering price of $20.00 and a price per per-funded warrant of $19.99. In aggregate, the Company received $129.0 million of gross proceeds less offering costs of $8.2 million The Company is not required under any circumstance to settle any of the pre-funded warrants for cash, and therefore classified the pre-funded warrants as permanent equity.

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. The Company received gross proceeds of $10.0 million for the sale and issuance of warrants to purchase common stock.

The warrants were separated into two tranches with 8,598,870 Tranche A warrants with an exercise price of $1.75 and aggregate proceeds of up to approximately $15.0 million, and 14,000,000 Tranche B warrants with an exercise price of $2.50 and aggregate proceeds of up to $35.0 million. The Tranche A warrants were immediately exercisable and were required to be exercised within 30 days of announcement of positive top-line data from the

randomized withdrawal period of Study C602. On September 26, 2023, the Company announced positive top-line data and subsequently received $15.0 million from the exercise of the Tranche A warrants. 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 FDA approval of DCCR for the treatment of PWS. During 2023, certain investors exercised their Tranche B warrants and the Company received $18.1 million. The receipt of the aggregate exercise price of up to $16.9 million for the remaining Tranche B warrants is contingent upon the exercise of such warrants.

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 March 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 March 2022 pre-funded warrant. The March 2022 pre-funded warrants are immediately exercisable and may be exercised at any time until all of the March 2022 pre-funded warrants are exercised in full. Each share of common stock or March 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.

In 2023, 2,070,934 March 2022 warrants were exercised for gross proceeds of $9.3 million and all 1,280,965 March 2022 pre-funded warrants were exercised using the cashless exercise option with no additional proceeds received by the Company.

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 December 31, 2023, the Company has sold 1,877,170 shares of common stock through the at the market program, totaling $7.4 million in net proceeds. The Controlled Equity Offering Sales Agreement was terminated in connection with the October 2, 2023 financing.

Other Common Stock Warrants

As of December 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 expire in November 2024. The Company also had

outstanding 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.

As of December 31, 2023 and December 31, 2022, the following table summarizes the Company's outstanding common stock warrants:


	As of December 31, 2023				As of December 31, 2022
	Number of Common Warrant Shares		Weighted Average Exercise Price per Share		Number of Common Warrant Shares		Weighted Average Exercise Price per Share		Expiration Date
Common stock warrants		7,904	$	388.94		7,904	$	388.94	November 2024
2018 PIPE warrants		—	$	-		34,241	$	30.00	December 2023
March 2022 Common warrants		1,929,066	$	4.50		4,000,000	$	4.50	March 2027
March 2022 Pre-funded warrants		—	$	-		1,280,965	$	0.15	March 2027
May 2023 Tranche A Pre-funded warrants		2,758,281	$	0.01		—	$	—	November 2026
May 2023 Tranche B warrants		6,750,000	$	2.50		—	$	—	November 2026 (1)
May 2023 Tranche B Pre-funded warrants		451,632	$	0.01		—	$	—	November 2026
October 2023 Pre-funded warrants		1,175,000	$	0.01		—	$	—	N/A
Total		13,071,883				5,323,110

(1) Subject to earlier expiration as described above.

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. 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. On May 25, 2023, the stockholders approved the Amended and Restated 2014 Plan which included an increase of 1.8 million shares available for grant and issuance. As of December 31, 2023, a total of 1,465 shares were 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 Company’s 2014 Equity Incentive 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 December 31, 2023, a total of 445,668 shares were available for future grant under the Inducement Plan.

Stock-based compensation expense

The Company recognized stock-based compensation expense related to options and restricted stock units granted to employees, directors and consultants for the years ended December 31, 2023 and 2022 of $5.9 million and $2.5 million, respectively. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. For the year ended December 31, 2023, the total income tax benefit related to stock-based compensation was $1.9 million, however, due to net operating losses and a full valuation allowance, no tax benefit was recognized in the financial statements. The total income tax benefit related to stock-based compensation for the year ended December 31, 2022 was zero.

Stock compensation expense was recognized in the consolidated statements of operations as follows (in thousands):


	Year ended
	December 31, 2023		December 31, 2022
Research and development	$	2,434	$	692
General and administrative		3,511		1,838
Total	$	5,945	$	2,530

Stock Options

The Company granted options to purchase 1,821,784 and 283,919 of the Company’s common stock during the years ended December 31, 2023 and 2022, respectively. There were no performance-based options granted in 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:


	Year Ended
	December 31, 2023	December 31, 2022
Expected life (years)	5.3-6.1	5.5-6.0
Risk-free interest rate	3.5%-4.5%	1.7%-3.1%
Volatility	98%-122%	88%-95%
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 years ended December 31, 2023 and 2022 as issued under the 2014 Plan and the Inducement Plan:


	Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	Outstanding			Share		(in years)		(in thousands)
Balance at December 31, 2021		408,329		$	46.28		7.94
Options granted		283,919			3.56
Options canceled/forfeited		(5,674	)		19.31
Balance at December 31, 2022		686,574		$	28.83		7.93
Options granted		1,821,784			6.18
Options exercised		(89,993	)		4.01
Options canceled/forfeited		(48,700	)		67.84
Balance at December 31, 2023		2,369,665		$	11.56		8.72	$	70,834
Options exercisable at December 31, 2023		797,988		$	18.31		7.76	$	20,320
Options vested and expected to vest at December 31, 2023		2,346,707		$	11.34		8.75	$	70,834

The weighted-average grant date fair value of employee options granted was $5.04 and $2.62 per share for the years ended December 31, 2023 and December 31, 2022, respectively. At December 31, 2023 total unrecognized employee stock-based compensation for options that are expected to vest was $9.1 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.5 years.

Restricted Stock Units

There were 420,710 and 8,965 restricted stock units granted by the Company during the years ended December 31, 2023 and December 31, 2022, respectively, to employees and certain directors. In 2023, 414,710 restricted stock units were granted to employees with a six-month vesting period, and all such restricted stock units vested during 2023. The restricted stock units granted to certain directors in 2022 were 100% vested on the grant date and represent compensation for past board services. 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 years ended December 31, 2023 and 2022 as issued under the 2014 Plan:


	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at December 31, 2021		29,050		$	57.75
Restricted stock units granted		8,965			5.33
Restricted stock units vested		(18,646	)		32.55
Restricted stock units cancelled/forfeited		(301	)		57.85
Outstanding at December 31, 2022		19,068		$	57.75
Restricted stock units granted		420,710			5.49
Restricted stock units vested		(423,248	)		6.43
Restricted stock units cancelled/forfeited		(996	)		5.25
Outstanding at December 31, 2023		15,534		$	43.92

The weighted-average grant-date fair value of all restricted stock units granted was $5.49 and $5.33 per share during the year ended December 31, 2023 and 2022, respectively. The fair value of all restricted stock units vested during the year ended December 31, 2023 and 2022 was $12.0 million and $0.1 million, respectively. At December 31, 2023, total unrecognized employee stock-based compensation related to restricted stock units was $0.2 million, which is expected to be recognized over the weighted-average remaining vesting period of 0.2 years.

2014 Employee Stock Purchase Plan

The Company’s board of directors and stockholders have adopted the 2014 Employee Stock Purchase Plan (the 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 December 31, 2023, there were no purchases by employees under this plan.

Defined Contribution Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Matching contribution by Company	$ 0	$ 0

Other Financial Statements Details - Intangible Assets (Detail) - Patents and Merger Costs [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Finite Lived Intangible Assets [Line Items]
Amount	$ 22,003	$ 22,003
Accumulated Amortization	(13,254)	(11,310)
Net Amount	$ 8,749	$ 10,693

Net Loss per Share - Schedule of Weighted-Average Common Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	16,492,132	8,397,088
Weighted-average common shares outstanding used to calculate diluted shares	16,492,132	8,397,088
Common Stock [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	15,040,036	7,409,165
Weighted-average common shares outstanding used to calculate diluted shares	15,040,036	7,409,165
March 2022 Pre-funded Warrants [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	290,665	987,923
Weighted-average common shares outstanding used to calculate diluted shares	290,665	987,923
May 2023 Tranche A Pre-funded Exchange Warrants [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	778,904
Weighted-average common shares outstanding used to calculate diluted shares	778,904
May 2023 Tranche B Pre-funded Exchange Warrants [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	92,801
Weighted-average common shares outstanding used to calculate diluted shares	92,801
October 2023 Pre-funded Warrants [Member]
Class of Stock [Line Items]
Weighted-average common shares outstanding used to calculate basic shares	289,726
Weighted-average common shares outstanding used to calculate diluted shares	289,726

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
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-Name Accounting Standards Codification
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-Paragraph 13
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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-Subparagraph (SX 210.4-08(d))
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-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
-Paragraph 13
-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Paragraph 14
-Subparagraph (b)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.5-02(28))
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Other Financial Statement Details (Tables)

12 Months Ended

Dec. 31, 2023

Other Financial Statement Details Disclosure [Abstract]

Schedule of Property and Equipment

Property and equipment are summarized in the following table (in thousands):


	December 31, 2023			December 31, 2022
Computer hardware	$	72		$	72
Furniture and fixtures		29			29
		101			101
Less accumulated depreciation and amortization		(89	)		(75	)
Total	$	12		$	26

Schedule of Intangible Assets

Intangible assets consist of the following (in thousands):


	December 31, 2023							December 31, 2022
	Amount		Accumulated Amortization			Net Amount		Amount		Accumulated Amortization			Net Amount
Patents and merger costs	$	22,003	$	(13,254	)	$	8,749	$	22,003	$	(11,310	)	$	10,693

Schedule of Future Amortization Expense

Future amortization expense for intangible assets over their remaining useful lives is as follows (in thousands):


Year ending December 31	Patents and trademarks
2024		1,944
2025		1,944
2026		1,944
2027		1,944
2028 and thereafter		973
Total	$	8,749

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 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	31,678,159	8,159,382
Common stock, shares outstanding	31,678,159	8,159,382

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 01, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	SOLENO THERAPEUTICS INC
Entity Central Index Key	0001484565
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Shell Company	false
Entity Emerging Growth Company	false
Document Annual Report	true
Document Transition Report	false
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 Financial Statement Error Correction [Flag]	false
Entity Common Stock, Shares Outstanding		32,460,579
Entity Public Float			$ 33.1
Auditor Name	Marcum LLP
Auditor Location	San Francisco, CA
Auditor Firm ID	688
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SLNO
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s Definitive Proxy Statement to be filed with the Commission pursuant to Regulation 14A in connection with the registrant’s 2024 Annual Meeting of Stockholders, to be filed subsequent to the date hereof, are incorporated by reference into Part III of this Report. Such Definitive Proxy Statement will be filed with the Securities and Exchange Commission not later than 120 days after the conclusion of the registrant’s fiscal year ended December 31, 2023. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.

Warrants - Additional Information (Detail)	12 Months Ended
Warrants - Additional Information (Detail)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) $ / shares shares	Aug. 26, 2022 shares	Dec. 19, 2018 $ / shares shares
Class Of Warrant Or Right [Line Items]
Change in fair value of common stock warrants \| $	$ 182,000	$ (30,000)
Issuance of common stock	100,000,000	100,000,000	100,000,000
Number of Common Warrant Shares	13,071,883	5,323,110
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				34,241
Exercise price of warrants (in dollars per share) \| $ / shares		$ 30		$ 30
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 prior to their expiration on December 21, 2023, entitled 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 adjustments.
Change in fair value of common stock warrants \| $	$ 200,000	$ (30,000)
Estimated warrants outstanding \| $	$ 0	$ 1,000
Exercise of warrants, shares	21,789
Issuance of common stock	9,683
Proceeds from warrant exercise \| $	$ 200,000
Number of Common Warrant Shares	12,452	34,241

Warrants

12 Months Ended

Dec. 31, 2023

Text Block [Abstract]

Warrants

Note 6. 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 prior to their expiration on December 21, 2023, entitled 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 adjustments.

In the event of a change of control of the Company, the holders of unexercised warrants had the option to 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 have been 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 re-measured the warrants at each balance sheet date until they were exercised or expire. Any change in the fair value is recognized as Other income (expense) in the Company’s consolidated statements of operations.

There were no 2018 PIPE Warrants outstanding at December 31, 2023 as the warrants were either exercised or expired, and the Company estimated the fair value of the liability for the 2018 PIPE Warrants at approximately $1 thousand at December 31, 2022. During 2023, 21,789 2018 PIPE Warrants were exercised for net proceeds of $0.2 million, and the Company issued 9,683 shares of common stock. The remaining 12,452 2018 PIPE Warrants expired. The increase of $0.2 million and the decrease of $30 thousand in the fair value of the liability for the 2018 PIPE Warrants during the years ended December 31, 2023 and 2022, respectively, was recorded as Other income in the consolidated statements of operations.

The Company has calculated the fair value of the 2018 PIPE Warrants using a Black-Scholes option-pricing model. The following summarizes certain key assumptions used in estimating the fair values:


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

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:

•

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

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Contingency [Line Items]
Increase (decrease) in valuation allowance	$ 8,900,000
Unrecognized assets and liabilities related to uncertain tax positions	2,900,000
Unrecognized tax benefits that would impact effective tax rate	0	$ 0
Unrecognized tax benefit offset by change in valuation allowance	2,900,000
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 500,000
Minimum [Member]
Income Tax Contingency [Line Items]
Research and development costs, amortization period	5 years
Maximum [Member]
Income Tax Contingency [Line Items]
Research and development costs, amortization period	15 years
U.S. Federal Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 206,700,000
Operating loss carryforwards, carried forward indefinitely	93,100,000
U.S. Federal Jurisdiction [Member] \| Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards	6,400,000
State Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	111,000,000
State Tax Jurisdiction [Member] \| Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards	3,400,000
Foreign Tax Authority [Member] \| Her Majesty's Revenue and Customs (HMRC) [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 2,300,000

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of Weighted-Average Common Shares Outstanding

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


	As of December 31,
	2023		2022
Common stock		15,040,036		7,409,165
March 2022 pre-funded warrants		290,665		987,923
May 2023 Tranche A pre-funded exchange warrants		778,904		-
May 2023 Tranche B pre-funded exchange warrants		92,801		-
October 2023 pre-funded warrants		289,726		-
Total		16,492,132		8,397,088

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


	As of December 31,
	2023		2022
Warrants issued to 2010/2012 convertible note holders to purchase common stock		6,804		6,804
Warrants issued to underwriter to purchase common stock		1,100		1,100
2018 PIPE warrants		-		34,241
March 2022 common warrants		1,929,066		4,000,000
May 2023 Tranche B warrants		6,750,000		-
Options to purchase common stock		2,369,665		686,574
Outstanding restricted stock units		15,534		19,068
Total		11,072,169		4,747,787

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (38,988)	$ (24,067)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,958	1,964
Noncash lease expense	321	290
Stock-based compensation expense	5,945	2,530
Change in fair value of common stock warrants	182	(30)
Change in fair value of contingent consideration	2,714	(712)
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(837)	113
Accounts payable	1,372	(1,477)
Accrued compensation	1,460	947
Accrued clinical trial site costs	171	(198)
Operating lease liabilities	(309)	(302)
Other liabilities	1,071	161
Net cash used in operating activities	(24,940)	(20,781)
Cash flows from investing activities:
Purchases of property and equipment	0	(13)
Net cash used in investing activities	0	(13)
Cash flows from financing activities:
Proceeds from sale of common stock, common stock warrants and pre-funded stock warrants, net of issuance costs	137,857	14,108
Proceeds from exercise of common stock warrants and pre-funded stock warrants, net of costs	41,815	0
Proceeds from stock option exercises	347	0
Tax withholding payments for net share-settled equity awards	0	(16)
Net cash provided by financing activities	180,019	14,092
Net increase (decrease) in cash and cash equivalents	155,079	(6,702)
Cash and cash equivalents, beginning of period	14,602	21,304
Cash and cash equivalents, end of period	169,681	14,602
Supplemental disclosure of non-cash investing and financing information
Operating lease right-of-use assets obtained in exchange for operating lease obligations	597	$ 0
Non-cash exercise of 2018 PIPE Warrants	$ 183

Other Financial Statement Details

12 Months Ended

Dec. 31, 2023

Other Financial Statement Details Disclosure [Abstract]

Other Financial Statement Details

Note 5. Other Financial Statement Details

Property and Equipment, Net

Property and equipment are summarized in the following table (in thousands):


	December 31, 2023			December 31, 2022
Computer hardware	$	72		$	72
Furniture and fixtures		29			29
		101			101
Less accumulated depreciation and amortization		(89	)		(75	)
Total	$	12		$	26

Depreciation expense was approximately $14 thousand and $20 thousand for the years ended December 31, 2023 and December 31, 2022, respectively.

Intangible Assets, Net

Intangible assets consist of the following (in thousands):


	December 31, 2023							December 31, 2022
	Amount		Accumulated Amortization			Net Amount		Amount		Accumulated Amortization			Net Amount
Patents and merger costs	$	22,003	$	(13,254	)	$	8,749	$	22,003	$	(11,310	)	$	10,693

Future amortization expense for intangible assets over their remaining useful lives is as follows (in thousands):


Year ending December 31	Patents and trademarks
2024		1,944
2025		1,944
2026		1,944
2027		1,944
2028 and thereafter		973
Total	$	8,749

Amortization expense was $1.9 million for the year ended December 31, 2023 and 2022.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Geographical Distribution of Loss before Income Taxes

The geographical distribution of loss before income taxes are summarized below (in thousands):


	December 31,
	2023			2022
United States	$	(39,180	)	$	(24,173	)
Foreign		192			106
Loss before income taxes	$	(38,988	)	$	(24,067	)

Provision for Income Tax Benefit by Applying Statutory Federal Income Tax Rate to Operating Loss

The provision for income tax benefit differs from the amount estimated by applying the statutory federal income tax rate to the operating loss due to the following (in thousands):


	December 31,
	2023			2022
Tax (benefit) on the loss before income tax expense computed at the federal statutory rate	$	(8,187	)	$	(5,055	)
State tax (benefit) at statutory rate, net of federal benefit		(505	)		(527	)
Foreign rate differential		6			-
Change in valuation allowance		8,934			5,702
Change in research and development credits		(1,631	)		(652	)
Stock based compensation		(600	)		(734	)
Change in fair value of warrants		38			(6	)
Change in fair value of contingent consideration		570			(150	)
Section 162(m) limitation		589			-
Change in net operating loss true up		39			739
Change in capital losses		—			405
Change in state rates		653			375
Other		94			(97	)
Provision for income tax benefit	$	—		$	—

Significant Components of Company's Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023			2022
Non-current deferred tax assets:
Federal and state net operating loss carryforwards	$	51,481		$	49,024
Research and other credits		6,352			4,146
Capitalized research and development		6,778			2,828
Reserves and accruals		655			547
Fixed assets		29			44
Capital loss carryover		432			555
Stock based compensation		2,013			2,682
Lease liability		85			42
Other deferred tax assets		54			72
Gross non-current deferred tax assets		67,879			59,940
Intangible assets		(1,837	)		(2,888	)
Right-of-use assets		(86	)		(35	)
Total non-current deferred tax liabilities		(1,923	)		(2,923	)
Total deferred tax assets		65,956			57,017
Valuation allowance		(65,956	)		(57,017	)
Net deferred tax assets	$	—		$	—

Summary of Gross Unrecognized Tax Benefits

The following tables summarize the activities of gross unrecognized tax benefits (in thousands):


	December 31,
	2023		2022
Beginning balance	$	1,936	$	1,557
Increase related to current year tax positions		1,002		379
Ending balance	$	2,938	$	1,936

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend rate	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	5 years 3 months 18 days	5 years 6 months
Risk-free interest rate	3.50%	1.70%
Volatility	98.00%	88.00%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	6 years 1 month 6 days	6 years
Risk-free interest rate	4.50%	3.10%
Volatility	122.00%	95.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Liquidity - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
Liquidity - Additional Information (Detail) - USD ($)	Oct. 02, 2023	May 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Cash And Cash Equivalents [Line Items]
Net loss			$ (38,988,000)	$ (24,067,000)
Accumulated deficit			(276,410,000)	(237,422,000)
Cash and cash equivalents			169,681,000	14,602,000
Net cash used in operating activities			(24,940,000)	(20,781,000)
Proceeds from issuance or sale of equity	$ 129,000,000		129,000,000
Securities Purchase Agreement [Member]
Cash And Cash Equivalents [Line Items]
Sale and issuance of warrants		$ 10,000,000
Tranche A [Member]
Cash And Cash Equivalents [Line Items]
Proceeds from warrant exercise			15,000,000
Tranche B [Member]
Cash And Cash Equivalents [Line Items]
Contingent receipt upon exerise of warrants and future performance of company			16,900,000
Proceeds from warrant exercise			18,100,000
Underwritten Public Offering [Member]
Cash And Cash Equivalents [Line Items]
Proceeds from warrant exercise			0
Underwritten Public Offering [Member] \| Securities Purchase Agreement [Member] \| Maximum [Member]
Cash And Cash Equivalents [Line Items]
Proceeds from sale of common stock, net of costs				$ 60,000,000
March 2022 Warrants [Member]
Cash And Cash Equivalents [Line Items]
Proceeds from warrant exercise			$ 9,300,000

Subsequent Events

12 Months Ended

Dec. 31, 2023

Subsequent Events [Abstract]

Subsequent Events

Note 13. Subsequent Events

On February 8, 2024, the Company entered into a six-month office license agreement to license 4,141 square feet of additional space adjacent to its existing office where the Company is currently located in Redwood City, California. The term of the new space expires October 31, 2024, unless terminated earlier in accordance with the license agreement.

Stockholders' Equity - Summary of Stock Option and Restricted Stock Unit Transactions (Detail) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options granted	1,821,784	283,919
2014 Plan and Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	686,574	408,329
Options granted	1,821,784	283,919
Options exercised	(89,993)
Options canceled/forfeited	(48,700)	(5,674)
Ending balance	2,369,665	686,574	408,329
Options exercisable at end of period (shares)	797,988
Options vested and expected to vest at end of period (shares)	2,346,707
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 28.83	$ 46.28
Options granted (in dollars per share)	6.18	3.56
Options exercised (in dollars per share)	4.01
Options canceled/forfeited (in dollars per share)	67.84	19.31
Ending balance (in dollars per share)	11.56	$ 28.83	$ 46.28
Options exercisable at end of period (in dollars per share)	18.31
Options vested and expected to vest at end of period (in dollars per share)	$ 11.34
Weighted Average Remaining Contractual Term
Options outstanding at end of period	8 years 8 months 19 days	7 years 11 months 4 days	7 years 11 months 8 days
Options exercisable at end of period	7 years 9 months 3 days
Options vested and expected to vest at end of period	8 years 9 months
Options outstanding at end of period	$ 70,834
Options exercisable at end of period	20,320
Options vested and expected to vest at end of period	$ 70,834

Income Taxes - Schedule of Geographical Distribution of Loss before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
United States	$ (39,180)	$ (24,173)
Foreign	192	106
Loss before income taxes	$ (38,988)	$ (24,067)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-SubTopic 20
-Topic 940
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481913/940-20-25-1

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Millions			12 Months Ended
	Aug. 26, 2022 $ / shares shares	Jun. 01, 2022	Dec. 31, 2023 USD ($) Segment $ / shares shares	Dec. 31, 2022 $ / shares shares
Schedule Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment			1
Estimated useful life			11 years
Reverse stock split ratio	0.0666	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
Essentialis, Inc. [Member]
Schedule Of Significant Accounting Policies [Line Items]
Net intangible assets acquired \| $			$ 22.0
Minimum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			3 years
Maximum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			5 years
ASU No. 2016-13 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2023
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true

Leases - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 312	$ 324
Short-term lease cost	44	29
Total operating lease cost	$ 356	$ 353

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Liabilities
Contingent liability for Essentialis purchase price	$ 11,549	$ 8,835
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	0	1
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability		8,836
Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability		1
Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	11,549	8,835
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability		8,836
Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Derivative Financial Instruments, Liabilities [Member] \| 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability		1
Level 3 [Member] \| Essentialis, Inc. [Member] \| Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 11,549	$ 8,835

Stockholders' Equity - Summary of Restricted Stock Unit Transactions (Detail) - Restricted Stock Units [Member] - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 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	420,710	8,965
Weighted-average grant date fair value
Restricted stock units granted (in dollars per share)	$ 5.49	$ 5.33
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	29,050
Restricted stock units granted	420,710	8,965
Restricted stock units vested	(423,248)	(18,646)
Restricted stock units cancelled/forfeited	(996)	(301)
Ending balance	15,534	19,068
Weighted-average grant date fair value
Beginning balance (in dollars per share)	$ 57.75	$ 57.75
Restricted stock units granted (in dollars per share)	5.49	5.33
Restricted stock units vested (in dollars per share)	6.43	32.55
Restricted stock units cancelled/forfeited (in dollars per share)	5.25	57.85
Ending balance (in dollars per share)	$ 43.92	$ 57.75

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lessee Lease Description [Line Items]
Operating lease, extension expiration	2025-05
Operating Lease, Liability, Current	$ 273	$ 155
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Operating Lease, Liability, Current	Operating Lease, Liability, Current
Long-term lease liabilities	$ 130	$ 0
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-term lease liabilities	Long-term lease liabilities
Increase in right of use assets	$ 600
Increase in lease liability	$ 600
Operating lease remaining term	17 months	5 months
Operating lease, weighted average discount rate	8.25%	9.00%
Redwood City, California [Member]
Lessee Lease Description [Line Items]
Operating lease, description	began in June 2021 and expired in May 2023
Operating lease, term of contract	24 months
Operating lease beginning date	2021-06
Operating lease, expiration	2023-05