Soleno Therapeutics (SLNO) 10-K 4 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 28, 2020	Jun. 28, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
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	No
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
Entity Common Stock, Shares Outstanding		44,686,811
Entity Public Float			$ 28
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 2020 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, 2019. 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.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 20,733,000	$ 23,099,000
Prepaid expenses and other current assets	411,000	529,000
Due from related party		64,000
Minority interest investment in former subsidiary		978,000
Total current assets	21,144,000	24,670,000
Long-term assets
Property and equipment, net	22,000	12,000
Operating lease right-of-use assets	398,000
Finance lease right-of-use assets	24,000
Intangible assets, net	16,525,000	18,469,000
Other long-term assets	59,000
Total assets	38,172,000	43,151,000
Current liabilities
Accounts payable	1,995,000	934,000
Accrued compensation	283,000	274,000
Accrued clinical trial site costs	1,999,000	320,000
Operating lease liabilities	305,000
Other current liabilities	382,000	349,000
Total current liabilities	4,964,000	1,877,000
Long-term liabilities
Contingent liability for Essentialis purchase price	5,938,000	5,649,000
Other long-term liabilities	147,000
Total liabilities	23,225,000	12,738,000
Commitments and contingencies (Note 8)
Stockholders’ equity
Common stock	45,000	32,000
Additional paid-in-capital	172,708,000	157,413,000
Accumulated deficit	(157,806,000)	(127,032,000)
Total stockholders’ equity	14,947,000	30,413,000
Total liabilities and stockholders’ equity	38,172,000	43,151,000
Series B Convertible Preferred Stock [Member]
Stockholders’ equity
Preferred stock
Series A Warrant Liability [Member]
Long-term liabilities
Warrant liability		49,000
2017 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	10,822,000	4,563,000
2018 PIPE Warrant Liability [Member]
Long-term liabilities
Warrant liability	$ 1,354,000	$ 600,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Preferred stock par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock shares authorized	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	44,658,054	31,755,169
Common stock, shares outstanding	44,658,054	31,755,169
Series B Convertible Preferred Stock [Member]
Preferred stock par value (in dollars per share)	$ 0.001
Preferred stock shares authorized	13,780	13,780
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, aggregate liquidation preference	$ 0	$ 0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses
Research and development	$ 16,267	$ 7,178
General and administrative	6,930	6,556
Change in fair value of contingent consideration	289	567
Total operating expenses	23,486	14,301
Operating loss	(23,486)	(14,301)
Other (expense) income
Change in fair value of warrants liabilities	(6,964)	522
Gain on deconsolidation of former subsidiary		1,994
Loss from minority interest investment	(478)	(160)
Interest and other income	154	104
Total other (expense) income	(7,288)	2,460
Loss from continuing operations	(30,774)	(11,841)
Loss from discontinued operations		(1,494)
Net loss	$ (30,774)	$ (13,335)
Loss per common share from continuing operations, basic and diluted	$ (0.90)	$ (0.56)
Loss per common share from discontinued operations, basic and diluted		(0.07)
Net loss per common share, basic and diluted	$ (0.90)	$ (0.64)
Weighted-average common shares outstanding used to calculate basic and diluted net loss per common share	34,142,478	20,975,479

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	2018 PIPE Warrant Liability [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]2018 PIPE Warrant Liability [Member]	Common Stock [Member]Essentialis, Inc. [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]2018 PIPE Warrant Liability [Member]	Additional Paid-In Capital [Member]Essentialis, Inc. [Member]	Accumulated Deficit [Member]
Balances at beginning at Dec. 31, 2017	$ 26,817			$ 19			$ 140,495			$ (113,697)
Balances at beginning (shares) at Dec. 31, 2017			4,571	19,238,972
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	829						829
Issuance of common stock on conversion of series B convertible preferred shares				$ 1			(1)
Issuance of common stock on conversion of series B convertible preferred shares (shares)			(4,571)	914,200
Issuance of restricted stock units under equity incentive plans	434						434
Issuance of restricted stock units under equity incentive plans (shares)				245,588
Issuance of common stock held back on acquisition of Essentialis						$ 1			$ (1)
Issuance of common stock held back on acquisition of Essentialis (Shares)						1,084,034
Issuance of common stock		$ 16,250			$ 11			$ 16,239
Issuance of common stock (shares)					10,272,375
Fair value at transaction date of warrants to purchase common stock		$ (582)						$ (582)
Net loss	(13,335)									(13,335)
Balances at ending at Dec. 31, 2018	30,413			$ 32			157,413			(127,032)
Balances at end (shares) at Dec. 31, 2018				31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	693						693
Issuance of restricted stock units under equity incentive plans	132						132
Issuance of restricted stock units under equity incentive plans (shares)				61,218
Issuance of common stock	14,483			$ 13			14,470
Issuance of common stock (shares)				12,841,667
Net loss	(30,774)									(30,774)
Balances at ending at Dec. 31, 2019	$ 14,947			$ 45			$ 172,708			$ (157,806)
Balances at end (shares) at Dec. 31, 2019				44,658,054

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Less transaction costs	$ 927	$ 250

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (30,774)	$ (13,335)
Loss from discontinued operations		(1,494)
Loss from continuing operations	(30,774)	(11,841)
Adjustments to reconcile net loss from continuing operations to net cash used in operating activities:
Depreciation and amortization	1,958	1,963
Noncash lease expense	386
Stock-based compensation expense	825	1,263
Change in fair value of stock warrants	6,964	(522)
Change in fair value of contingent consideration	289	567
Gain on deconsolidation of former subsidiary		(1,994)
Operating loss of minority interest investment	478	160
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	10	(60)
Due from related party	64	(64)
Accounts payable	1,061	249
Accrued compensation	9	(103)
Accrued clinical trial site costs	1,679	321
Operating lease liabilities	(360)
Other liabilities	36	(261)
Net cash used in continuing operating activities	(17,375)	(10,322)
Net cash used in discontinued operating activities		(1,361)
Net cash used in operating activities	(17,375)	(11,683)
Cash flows from investing activities:
Purchases of property and equipment	(21)	(8)
Security deposit on sublease	(59)
Security deposit received from expired lease	108
Proceeds from sale of minority interest investment in former subsidiary	500
Net cash provided by (used in) continuing investing activities	528	(8)
Net cash used in discontinued investing activities		(172)
Net cash provided by (used in) investing activities	528	(180)
Cash flows from financing activities:
Proceeds from sale of common stock and common stock warrants, net of costs	14,483	16,302
Principal paid on finance lease liabilities	(2)
Net cash provided by continuing financing activities	14,481	16,302
Net cash provided by discontinued financing activities		1,525
Net cash provided by financing activities	14,481	17,827
Net increase (decrease) in cash and cash equivalents	(2,366)	5,964
Cash and cash equivalents, beginning of period	23,099	17,135
Cash and cash equivalents, end of period	20,733	23,099
Supplemental disclosures of non-cash investing and financing information
Accrued liability for cost of issuing common stock		52
Warrants issued in connection with sale of common stock		582
Continuing Operations [Member]
Cash flows from financing activities:
Net increase (decrease) in cash and cash equivalents	$ (2,366)	5,972
Discontinued Operations [Member]
Cash flows from financing activities:
Net increase (decrease) in cash and cash equivalents		$ (8)

Overview

Overview	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Overview	Note 1. Overview Soleno Therapeutics, Inc. (the “Company” or “Soleno”) was incorporated in the State of Delaware on August 25, 1999, and is located in Redwood City, California. On May 8, 2017, Soleno received stockholder approval to amend its Amended and Restated Certificate of Incorporation to change its name from “Capnia, Inc.” to “Soleno Therapeutics, Inc.” The Company Diazoxide Choline Controlled Release tablets, or DCCR Prader-Willi Syndrome, or PWS The Company initially established its operations as a diversified healthcare company that developed and commercialized innovative diagnostics, devices and therapeutics addressing unmet medical needs, which consisted of: precision metering of gas flow technology marketed as Serenz ® Allergy Relief, or Serenz, and the CoSense ® End-Tidal Carbon Monoxide Monitor, or CoSense, which measures End-Tidal Carbon Monoxide and aids in the detection of excessive hemolysis, a condition in which red blood cells degrade rapidly and which can lead to adverse neurological outcomes; and, products that included temperature probes, scales, surgical tables, and patient surfaces. On March 7, 2017, the Company completed its merger, or the Merger, with Essentialis, Inc., a Delaware corporation, or Essentialis, in accordance with the Merger Agreement by and between Soleno Therapeutics and Essentialis dated December 22, 2016, or the Merger Agreement. After the Merger, the Company’s primary focus has been the development and commercialization of novel therapeutics for the treatment of rare diseases. Essentialis was a privately-held, clinical-stage biotechnology company focused on the development of breakthrough medicines for the treatment of rare diseases in which there is increased mortality and risk of cardiovascular and endocrine complications. Prior to the Merger, Essentialis’s efforts were focused primarily on developing and testing product candidates that target the ATP-sensitive potassium channel, a metabolically-regulated membrane protein whose modulation has the potential to impact a wide range of rare metabolic, cardiovascular, and central nervous system diseases. Essentialis had tested DCCR as a treatment for PWS, a complex metabolic/neurobehavioral disorder. DCCR has orphan designation for the treatment of PWS in the United States, or U.S., as well as in the European Union, or E.U. Subsequent to the Merger with Essentialis described above, the Company determined to divest, sell or dispose of its business efforts focused on the development and commercialization of its Serenz and CoSense technologies. Accordingly, and pursuant to ASC 205-20-45-10, any assets and liabilities related to the discontinued activities of CoSense and Serenz were presented separately as held for sale items, and the related operations reported herein for the CoSense and Serenz activities are reported as discontinued operations in the statements of operations. The Company’s current research and development efforts are primarily focused on advancing its lead candidate, DCCR tablets, for the treatment of PWS, through late-stage clinical development.

Going Concern and Management's

Going Concern and Management's Plans	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Going Concern and Management's Plans	Note 2. Going Concern and Management’s Plans The Company had a net loss of $30.8 million during 2019 and has an accumulated deficit of $157.8 million at December 31, 2019 resulting from having incurred losses since its inception. The Company had $20.7 million of cash on hand at December 31, 2019 and used $17.4 million of cash in its operating activities during 2019. The Company has financed its operations principally through issuances of equity securities. On October 25, 2019, the Company sold 12,841,667 shares of common stock in an underwritten public offering at a price of $1.20 per share for net proceeds of $14.5 million. The accompanying consolidated financial statements have been prepared under the assumption the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern. The Company expects to continue incurring losses for the foreseeable future and will be required to raise additional capital to complete its clinical trials, pursue product development initiatives and penetrate markets for the sale of its products. Management believes that the Company will continue to have access to capital resources through possible public or private equity offerings, debt financings, corporate collaborations or other means, but the Company’s access to such capital resources is uncertain and is not assured. If the Company is unable to secure additional capital, it may be required to curtail its clinical trials and development of new products and take additional measures to reduce expenses in order to conserve its cash in amounts sufficient to sustain operations and meet its obligations. These measures could cause significant delays in the Company’s efforts to complete its clinical trials and commercialize its products, which is critical to the realization of its business plan and the future operations of the Company. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of asset amounts or the classification of liabilities that might be necessary should it be unable to continue as a going concern. Management believes that the Company does not have sufficient capital resources to sustain operations through at least the next twelve months from the date of this filing. Additionally, in view of the Company’s expectation to incur significant losses for the foreseeable future it will be required to raise additional capital resources in order to fund its operations, although the availability of, and the Company’s access to such resources is not assured. Accordingly, management believes that there is substantial doubt regarding the Company’s ability to continue operating as a going concern within one year from the date of filing these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 3. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the applicable rules and regulations of the Securities and Exchange Commission, or SEC. 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. Certain amounts from prior periods have been reclassified to conform to the current period presentation, including certain current liabilities within the Consolidated Balance Sheets and Consolidated Statements of Cash Flows, certain immaterial amounts within the Consolidated Statements of Operations, and the presentation of restricted stock units and the related expense within the Consolidated Statements of Stockholders’ Equity and Consolidated Statements of Cash Flows. 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 included in the financial statements include the valuation of deferred income tax assets, the valuation of financial instruments, stock-based compensation, value and life of acquired intangibles, and the valuation of contingent liabilities 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 one U.S. commercial bank. Cash and cash equivalents deposited with this commercial bank exceeded the Federal Deposit Insurance Corporation insurable limit at December 31, 2019 and 2018. The Company expects the maintenance of balances in excess of insurable limits will continue. 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 United States of America. Cash and Cash Equivalents The Company considers all highly liquid investments, including its money market fund, purchased with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held in institutions in the U.S. and the U.K. and include deposits in a money market fund which was unrestricted as to withdrawal or use. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of payments primarily related to insurance and short-term deposits. Prepaid expenses are initially recorded upon payment and are expensed as goods or services are received. Patent In March 2017, the Company completed the acquisition of Essentialis, Inc., a Delaware corporation, or Essentialis in accordance with the Merger Agreement by and between Soleno Therapeutics and Essentialis dated December 22, 2016. The merger transaction has been accounted for as an asset acquisition under the acquisition method of accounting and accordingly, the value of asset acquired in the amount of $22.0 million was assigned to the identifiable intangible asset relating to the patent for DCCR, which patent expires in June 2028. 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. Equity Method Investment Equity method investments are equity securities in investees not controlled by the Company, but over which the Company has the ability to exercise significant influence. The Company’s equity method investment is measured at fair value minus impairment, if any, plus or minus the Company’s share of equity method investee income or loss. The Company’s equity method investment in Capnia, Inc. is classified as Minority interest investment in former subsidiary in the consolidated balance sheet as of December 31, 2018 and was initially measured at fair value. (See Note 9.) The Company sold its equity method investment in Capnia in September 2019. 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 with finite lives are amortized on a straight-line basis over their estimated useful lives of 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 and benefits, consultant fees, prototype expenses, certain facility costs and other costs associated with clinical trials, net of reimbursed amounts. 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. Certain research and development expenses are reported as discontinued operations. (See Note 9.) 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. The loss from discontinued operations is reported net of the related effect for income taxes in the statements of operations. Convertible Preferred Stock and other Hybrid Instruments The Company’s convertible preferred stock was classified as permanent equity on its consolidated balance sheet in accordance with authoritative guidance for the classification and measurement of hybrid securities and distinguishing liability from equity instruments. The preferred stock is not redeemable at the option of the holder. Further, the Company evaluated its Series B Convertible Preferred Stock and determined that it is considered an equity host under ASC 815, Derivatives and Hedging 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 Series A, Series C, the 2017 PIPE Warrants and 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. 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 of the award. Stock options generally vest over four years. The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. If we had made different assumptions, our stock-based compensation expense, net loss and net loss per share of common stock could have been significantly different. These assumptions include: • Expected volatility: The Company calculates the estimated volatility rate based the volatility of its common stock together with comparable companies in its industry. • Expected term: The Company does not believe it is able to rely on its historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term for use in estimating the fair value-based measurement of our options. Therefore, the Company has opted to use the “simplified method” for estimating the expected term of options. • 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 do 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 Accounting Standards Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Codification (ASC) 842, Leases. Leases requires lessees to capitalize most lease obligations as right-of-use assets with a corresponding liability on the balance sheet. Leases are classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The guidance is effective for all public business entities and certain not-for-profit entities in fiscal years beginning after December 15, 2018, and for all other entities in fiscal years beginning after December 15, 2020. Early adoption is permitted. As the Company was an emerging growth company until December 31, 2019 and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, it adopted the standard as of January 1, 2019 on December 31, 2019. The Company adopted ASC 842 using the optional modified retrospective method and will not restate comparative periods. The Company has elected to apply the “practical expedient package”, which permits it to not reassess previous conclusions around lease identification, lease classification, and initial direct costs. Further, the Company will make an accounting policy election to exclude leases with terms of twelve months or less from the recognition requirements. The Company did not elect the use of the hindsight practical expedient. As a result of the adoption of the standard on January 1, 2019, the Company recognized lease liabilities based on the present value of the total fixed payments for its leases in the amount of approximately $322,000 and ROU assets of approximately $301,000 on its balance sheet. The adoption of the new standard did not have a material impact on the Company’s Statement of Operations or Cash Flows. In June 2018, the FASB issued ASU 2018-07, “ Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting” In August 2018, SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification Recently Issued Accounting Standards In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. In December 2019, the FASB issued ASU 2019-12: “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Note 4. Fair Value of Financial Instruments The carrying value of the Company’s cash, cash equivalents and accounts payable, approximate fair value due to the short-term nature of these items. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: • Level I — • Level II — • Level III — The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands). Fair Value Measurements at December 31, 2019 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 10,822 $ — $ — $ 10,822 2018 PIPE warrant liability 1,354 — — 1,354 Essentialis purchase price contingency liability 5,938 — — 5,938 Total common stock warrant and contingent consideration liability $ 18,114 $ - $ — $ 18,114 Fair Value Measurements at December 31, 2018 Total Level 1 Level 2 Level 3 Liabilities Series A warrant liability $ 49 $ 49 $ — $ — 2017 PIPE warrant liability 4,563 — — 4,563 2018 PIPE warrant liability 600 — — 600 Essentialis purchase price contingency liability 5,649 — — 5,649 Total common stock warrant and contingent consideration liability $ 10,861 $ 49 $ - $ 10,812 The Series A Warrant is a registered security that trades on the open market and the fair value of the Series A Warrant liability is based on the publicly quoted trading price of the warrants which is listed on and obtained from NASDAQ. Accordingly, the fair value of Series A Warrants is a Level 1 measurement. The fair value measurement of the Series C Warrants is based on significant inputs that are unobservable and thus represent Level 3 measurements. The Company’s estimated fair value of the Series C Warrant liability is calculated using the Black-Scholes valuation model, which is equivalent to fair value computed using the Binomial Lattice Option Model. Key assumptions include the volatility of the Company’s stock, the expected warrant term, expected dividend yield and risk-free interest rates. During the periods presented, the Company has not changed the manner in which it values liabilities that are measured at fair value using Level 3 inputs. 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 1 and Level 3 warrants, which are treated as liabilities (dollars in thousands). Series A Warrants Series C Warrants 2017 PIPE Warrants 2018 PIPE Warrants Purchase Price Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Contingent Liability Balance at January 1, 2019 485,121 $ 49 118,083 $ — 6,024,425 $ 4,563 513,617 $ 600 $ 5,649 Expiration of Series A Warrants (485,121 ) (49 ) — — — — — — — Change in value of Series C Warrants — — — — — — — — Change in value of 2017 PIPE Warrants — — — — — 6,259 — — — Change in value of 2018 PIPE Warrants — — — — — — — 754 — Change in value of contingent liability — — — — — — — — 289 Balance at December 31, 2019 — $ — 118,083 $ — 6,024,425 $ 10,822 513,617 $ 1,354 $ 5,938

Other Financial Statement Detai

Other Financial Statement Details	12 Months Ended
	Dec. 31, 2019
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, 2019 December 31, 2018 Computer hardware $ 52 $ 67 Computer software — 2 Furniture and fixtures 1 23 Leasehold improvements — 13 53 105 Less accumulated depreciation and amortization (31 ) (93 ) Total $ 22 $ 12 Depreciation expense was approximately $11,000 and $19,000 for the years ended December 31, 2019 and December 31, 2018, respectively. Intangible Assets, Net Intangible assets consist of the following (in thousands). December 31, 2019 December 31, 2018 Amount Accumulated Amortization Net Amount Amount Accumulated Amortization Net Amount Patents and merger costs $ 22,003 $ (5,478 ) $ 16,525 $ 22,003 $ (3,534 ) $ 18,469 Total $ 22,003 $ (5,478 ) $ 16,525 $ 22,003 $ (3,534 ) $ 18,469 Future amortization expense for intangible assets over their remaining useful lives is as follows (in thousands). Year ending December 31 Patents and trademarks 2020 $ 1,944 2021 1,944 2022 1,944 2023 1,944 2024 1,944 2025 and thereafter 6,805 Total $ 16,525 Amortization expense was $1.9 million for the year ended December 31, 2019 and 2018.

Warrant Liabilities

Warrant Liabilities	12 Months Ended
	Dec. 31, 2019
Text Block [Abstract]
Warrant Liabilities	Note 6. Warrant Liabilities The Company has issued multiple warrant series, of which the Series A Warrants, Series C Warrants, the 2017 PIPE Warrants and the 2018 PIPE Warrants (the “Warrants”) are considered liabilities pursuant to the guidance established by ASC 815 Derivatives and Hedging. Accounting Treatment The Company accounts for the Warrants in accordance with the guidance in ASC 815 The Company classified the Warrants as long-term liabilities at their fair value and will re-measure the warrants at each balance sheet date until they are exercised or expire. Any change in the fair value is recognized as other income (expense) in the Company’s consolidated statements of operations. Series A Warrants The Company issued 489,921 Series A Warrants to purchase shares of its common stock at an exercise price of $32.50 per share in connection with the unit offering offered in the Company’s initial public offering, or the IPO, in November 2014. The Series A Warrants were exercisable prior to the expiration of the five-year term on November 12, 2019. Upon the completion of the IPO, the Series A Warrants started trading on the NASDAQ under the symbol SLNOW. As the Series A Warrants are publicly traded, the Company used the closing price on the measurement date to determine the fair value of the Series A Warrants. The Series AWarrants contain a fundamental transactions provision that permitted their settlement in cash at fair value at the option of the holder upon the occurrence of a change in control. Such change in control events include tender offers or hostile takeovers, which are not within the sole control of the Company as the issuer of these warrants. Accordingly, the Warrants were considered to have a cash settlement feature that precludes their classification as equity instruments. Settlement at fair value upon the occurrence of a fundamental transaction would be computed using the Black Scholes Option Pricing Model, which approximates the binomial lattice model. Since their issuance, a total of 4,800 Series A Warrants have been exercised. On November 12, 2019, the remaining Series A Warrants expired. The decrease in fair value of approximately $49,000 from December 31, 2018 was recorded as other income (expense) in the consolidated statements of operations. Series C Warrants On March 5, 2015, the Company entered into separate agreements with certain Series B Warrant holders, who agreed to exercise their Series B Warrants to purchase an aggregate of 117,902 shares of the Company’s common stock at an exercise price of $32.50 per share, resulting in the de-recognition of $6.7 million of the previously issued Series B Warrant liability and gross proceeds to the Company of $3.8 million based on the exercise price of the Series B Warrants. In April 2015, the Company issued a tender offer to the remaining holders of Series B Warrants to induce the holders to cash exercise the outstanding Series B Warrants in exchange for new Series C Warrants with an exercise price of $31.25 per share that expire on March 5, 2020. The tender offer was extended to Series B Warrant holders under a registration statement filed with the SEC on Form S-4, which was declared effective on June 25, 2015 and expired on July 24, 2015. During July 2015, certain Series B Warrant holder(s) tendered their Series B Warrants under the tender offer, which resulted in the issuance of 181 shares of the Company’s common stock, the issuance of 181 Series C Warrants and proceeds to the Company of approximately $6,000. In connection with this exercise of the Series B Warrants, the Company issued to each investor who exercised Series B Warrants, new Series C Warrants for the number of shares of the Company’s common stock underlying the Series B Warrants that were exercised. Each Series C Warrant is exercisable at $31.25 per share and will expire on March 5, 2020. The Series C Warrants contract further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate volume weighted average price, or VWAP, of the shares into which each Warrant is convertible into in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of these securities and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds related to the warrant financings to the registration payment arrangement. The Warrants also contain a fundamental transactions provision that permits their settlement in cash at fair value at the option of the holder upon the occurrence of a change in control. Such change in control events include tender offers or hostile takeovers, which are not within the sole control of the Company as the issuer of these warrants. Accordingly, the Warrants are considered to have a cash settlement feature that precludes their classification as equity instruments. Settlement at fair value upon the occurrence of a fundamental transaction would be computed using the Black Scholes Option Pricing Model, which approximates the binomial lattice model. The Series C Warrants are exercisable into 118,083 shares of the Company’s common stock. As of December 31, 2019, the fair value of the Series C Warrants was determined to be zero, consistent with the value as of December 31, 2018. The Company has calculated the fair value of the Series C Warrants using a Black-Scholes pricing model. The Black-Scholes pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The Company used the following inputs. December 31, 2019 December 31, 2018 Volatility 90 % 90 % Contractual term (years) 0.17 1.17 Expected dividend yield — % — % Risk-free rate 1.52 % 2.60 % Warrants Issued as Part of the Units in the 2017 PIPE Offering The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holders to purchase 6,024,425 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS. The exercise price and number of shares of common stock issuable upon exercise of the 2017 PIPE Warrants may be adjusted in certain circumstances, including in the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2017 PIPE Warrants will not be reduced below $1.72. In the event of a change of control of the Company, the holders of unexercised warrants may present their unexercised warrants to the Company, or its successor, to be purchased by the Company, or its successor, in an amount equal to the per share value determined by the Black Scholes methodology. As of December 31, 2019, the fair value of the 2017 PIPE Warrants was estimated at $10.8 million. The increase in the fair value of the liability for the 2017 PIPE Warrants of $6.3 million during the year ended December 31, 2019 was recorded as other expense in the consolidated statements of operations. The Company has calculated the fair value of the 2017 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values. December 31, 2019 December 31, 2018 Volatility 99 % 75 % Contractual term (years) 1.0 2.0 Expected dividend yield — % — % Risk-free rate 1.60 % 2.51 % Warrants Issued as Part of the Units in the 2018 PIPE Offering The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders to purchase 513,617 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023. The exercise price and number of shares of common stock issuable upon exercise of the 2018 PIPE Warrants may be adjusted in certain circumstances, including in the event of a stock split, stock dividend, extraordinary dividend, or recapitalization, reorganization, merger or consolidation. However, the exercise price of the 2018 PIPE Warrants will not be reduced below $2.00. In the event of a change of control of the Company, the holders of unexercised warrants may present their unexercised warrants to the Company, or its successor, to be purchased by the Company, or its successor, in an amount equal to the per share value determined by the Black Scholes methodology. As of December 31, 2019, the fair value of the 2018 PIPE Warrants was estimated at $1.4 million. The approximate $754,000 increase in the fair value of the liability for the 2018 PIPE Warrants during the year ended December 31, 2019 was recorded as other expense in the consolidated statements of operations. The Company has calculated the fair value of the 2018 PIPE Warrants using a Monte Carlo simulation of a geometric Brownian motion model. The Monte Carlo simulation pricing model requires the input of highly subjective assumptions including the expected stock price volatility. The following summarizes certain key assumptions used in estimating the fair values. December 31, 2019 December 31, 2018 Volatility 99 % 75 % Contractual term (years) 4.0 5.0 Expected dividend yield — % — % Risk-free rate 1.56 % 2.51 % The Monte Carlo simulation of a geometric Brownian motion model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates. • Volatility: The Company calculates the estimated volatility rate based on the volatilities of common stock of comparable companies in its industry together with the volatility of its own stock. • Contractual term: The expected life of the warrants, which is based on the contractual term of the warrants. • Expected dividend yield: The Company has never declared or paid any cash dividends and does not currently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero. • Risk-free rate: The risk-free interest rate is based on the U.S. Treasury rate for similar periods as those of expected volatility.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Note 7. Leases Leases The Company adopted ASC 842: Leases, as of January 1, 2019, using the modified retrospective method as described in Note 3, without adjusting prior comparative periods. 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 the classification of the lease, operating or finance, using the classification criteria described in ASC 842. The Company has elected not to separate lease components from non-lease components, such as common area maintenance charges, and instead accounts for the lease and non-lease components as a single component. The Company’s previous operating lease for its headquarters facility office space in Redwood City, California, terminated in August 2019, along with the related subleases. One of the subleases was with Capnia, of which the Company was a joint owner until September 2019. See note 9 for further information. Sublease income received from Capnia during the year ended December 31, 2019 was approximately $65,000. In July 2019, the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021. The lease also provides the Company with the right to use office furniture in the space and allows the purchase of this furniture at the end of the lease term for $1. The lease agreement requires monthly lease payments of approximately $29,000 beginning in November of 2019, with an increase to approximately $30,000 per month in September of 2020. The Company has accounted for the new lease as an operating lease for the office space and a finance lease for the office furniture, based on their relative standalone prices. As of December 31, 2019, the Company’s operating lease right-of-use assets and finance lease right-of-use assets were approximately $398,000 and $24,000, respectively. The Company’s current operating lease liabilities were approximately $305,000 as of December 31, 2019. Each of these amounts appears as a separate line within the Company’s consolidated balance sheet. The Company’s current finance lease liabilities were approximately $17,000 as of December 31, 2019 and are included in other current liabilities on the consolidated balance sheet. As of December 31, 2019 the Company’s long-term operating lease liabilities were approximately $139,000 and the long-term finance lease liabilities were approximately $8,000, both of which are included in other long-term liabilities on the consolidated balance sheet. The components of lease expense during the year ended December 31, 2019 were as follows (in thousands): Operating lease cost: Operating lease cost $ 418 Sublease income (173 ) Total operating lease cost $ 245 Finance lease cost: Amortization of right-of-use assets $ 3 Interest on lease liabilities 1 Total finance lease cost $ 4 For the year ended December 31, 2018, rent expense was approximately $323,000, net of sublease income of approximately $277,000. Supplemental cash flow information related to leases was as follows for the year ended December 31, 2019 (in thousands): Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 219 Operating cash flows from finance leases $ 1 Financing cash flows from finance leases $ 2 Right-of use assets obtained in exchange for lease obligations (noncash): Operating leases $ 484 Finance leases $ 27 The following is a schedule by year of future maturities of the Company’s lease liabilities as of December 31, 2019 (in thousands): Operating Leases Finances Lease 2020 $ 336 $ 19 2021 143 8 Total lease payments 479 27 Less interest (34 ) (2 ) Total $ 445 $ 25 The weighted-average remaining lease term and discount rate related to the Company’s lease liabilities as of December 31, 2019 were 1.4 years and 10%, respectively, for both the operating leases and finance leases. The Company lease discount rates are based on estimates of its incremental borrowing rate, as the discount rates implicit in the Company’s leases cannot be readily determined. As the Company does not have any outstanding debt the Company estimates the incremental borrowing rate based on its estimated credit rating and available market information.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
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.

CoSense Joint Venture Agreement

CoSense Joint Venture Agreement and Discontinued Operations	12 Months Ended
	Dec. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
CoSense Joint Venture Agreement and Discontinued Operations	Note 9. CoSense Joint Venture Agreement and Discontinued Operations In December 2017, the Company entered into a joint venture with OptAsia Healthcare Limited, or OAHL, with respect to its CoSense product by agreeing to sell shares of Capnia, its then wholly-owned subsidiary, to OAHL. CoSense was Soleno’s first Sensalyze Technology Platform product to receive 510(k) clearances from the FDA and CE Mark certification. The Company’s entry into the joint venture resulted from a comprehensive review of strategic alternatives for its legacy products and product candidates following its transition to a primarily therapeutic drug product company. The terms of the Joint Venture Agreement provide that OAHL would invest up to a total of $2.2 million in Capnia’s common shares on an incremental quarterly basis commencing in December 2017. OAHL was also responsible for funding a portion of the Capnia operations. The Joint Venture Agreement provided that Capnia would issue shares of common stock to OAHL based on a negotiated price of $1.00 per share when the cumulative investment made by OAHL equaled or exceeded $1.2 million. For financial reporting purposes, Capnia’s assets, liabilities and results of operations had historically been consolidated with those of the Company. During October 2018, the Company and OAHL determined and agreed that the cumulative investment made by OAHL exceeded $1.2 million during the quarter ended September 30, 2018. Accordingly, on October 16, 2018, Capnia issued 1,690,322 shares of its common stock to OAHL, representing 53% of its outstanding shares. After the share issuance the Company no longer held a controlling interest in Capnia and resulted in the deconsolidation of Capnia’s financial statements from those of the Company and a $2.0 million gain was recognized in the fourth quarter of 2018 as a result of the deconsolidation. Of this amount, $1.2 million related to the remeasurement of the Company's retained interest in the joint venture to fair value which was measured based on the negotiated price of $1.00 per share for Soleno’s remaining ownership of 1,480,000 shares less a 23% discount for lack of control over Capnia. The total gain was included in other income from continuing operations on the Company's consolidated statements of operations. The remaining 47% investment in Capnia was classified as an equity method investment and presented as a Minority interest investment in former subsidiary in the consolidated balance sheet. During September 2019, the Company sold its remaining 47% investment in Capnia to Sinon for a total purchase price of $500,000. As of the sale date, the Company had a minority interest investment in former subsidiary balance of approximately $467,000, after recording approximately $511,000 for its share of Capnia’s losses during 2019 up until the date of sale, which is included in the line titled “Loss from minority interest investment” in the Company’s consolidated statements of operations. A gain of approximately $33,000 was recognized upon the sale and is presented, together with the Company’s share of Capnia’s net losses during the period, in the consolidated statements of operations in the line titled “Loss from minority interest investment”. Following the transaction, the Company has no interest remaining in Capnia and the previous joint venture agreement with OAHL has been terminated. There were no assets or liabilities held for sale as of December 31, 2019, or December 31, 2018, after the deconsolidation of Capnia in October 2018, and no discontinued operations during the year ended December 31, 2019. The components of the Statements of Operations presented as Discontinued Operations during the year ended December 31, 2018 follow (in thousands). Product revenue $ 62 Cost of product revenue 32 Gross profit 30 Expenses Research and development 1,106 Sales and marketing 25 General and administrative 393 Total expenses 1,524 Operating loss (1,494 ) Net loss from discontinued operations $ (1,494 ) Stock-based compensation expense of approximately $76,000 and was classified in discontinued operations for the years ended December 31, 2018. There were no discontinued operations during the year ended December 31, 2019.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity	Note 10. Stockholders’ Equity Convertible Preferred Stock The Company is authorized to issue 10,000,000 shares of Preferred Stock. The Company had issued a total of 13,780 shares of Series B Convertible Preferred Stock pursuant to the Securities Purchase Agreement entered into on June 29, 2016 with Sabby Management, LLC. As of December 31, 2019, there were no shares of Series B Convertible Preferred Stock outstanding as all such previously issued shares had been converted to common shares. Common Stock On March 7, 2017, the Company completed the Merger with Essentialis and issued 3,783,388 shares of common stock to shareholders of Essentialis. Pursuant to the terms of the Merger Agreement, the Company held back shares of common stock as partial recourse to satisfy indemnification claims. Effective March 7, 2018, on the one-year anniversary of the closing of the merger, the Company issued 180,667 shares for the previously held back amount. In the second quarter of 2018 there were 903,367 additional shares of common stock issued upon the achievement of a development milestone. In total, 4,867,422 shares of common stock were issued to Essentialis stockholders. Additionally, upon the achievement of certain commercial milestones associated with the sale of Essentialis’ product in accordance with the terms of the Merger Agreement, the Company is obligated to make cash earnout payments of up to a maximum of $30.0 million to Essentialis stockholders. The merger consideration described above will be reduced by any such shares of common stock issuable, or cash earnout payments payable, to Essentialis’ management carve-out plan participants and other service providers of Essentialis, in each case, in accordance with the terms of the Merger Agreement. On January 27, 2017, the Company entered into the 2017 Aspire Purchase Agreement with Aspire Capital, which provided that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital was committed to purchase up to an aggregate of $17.0 million in value of shares of the Company’s common stock over the 30-month term of the purchase agreement. Additionally, on the date of the closing of the financing, as defined in the Merger Agreement, the Company issued to Aspire Capital, and Aspire Capital purchased from the Company an aggregate of $2.0 million of the Company’s common stock. On December 19, 2018, the Company entered into a Securities Purchase Agreement with certain purchasers, pursuant to which the Company sold and issued 10,272,375 units at a price per unit of $1.61, for aggregate gross proceeds of $16.5 million. Each unit consisted of one share of the Company’s common stock and a warrant to purchase 0.05 shares of the Company’s common stock at an exercise price of $2.00 per share, for an aggregate of 10,272,375 shares of common stock and corresponding warrants to purchase an aggregate of 513,617 shares of common stock, together with the shares of common stock are referred to as the 2018 Resale Shares. The Company also granted certain registration rights to these stockholders, pursuant to which, among other things, the Company prepared and filed a registration statement with the SEC to register for resale the 2018 Resale Shares. The registration statement was declared effective in April 2019. On October 25, 2019, the Company sold 12,841,667 shares of its common stock, including 1,675,000 shares sold upon full exercise of the underwriters’ option to purchase additional shares, at a public offering price of $1.20 per share. The net proceeds of the offering were $14.5 million, after deducting the underwriting discount and other offering expenses. Equity Incentive Plans The Company has the 2014 Equity Incentive Plan, or 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 of Directors has the authority to determine to whom stock options will be granted, the number of options, the term, and the exercise price. Options are to be granted at an exercise price not less than fair value. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price of an option will not be less than 110% of fair value. The vesting period is normally monthly over a period of 4 years from the vesting date. The contractual term of an option is no longer than five years for ISOs for which the grantee owns greater than 10% of the voting power of all classes of stock and no longer than ten years for all other options. The terms and conditions governing restricted stock units is at the sole discretion of the Board. As of December 31, 2019, a total of 615,760 shares are available for future grant under the 2014 Plan. 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, 2019 and 2018 of approximately $825,000 and $1.3 million, respectively, of which approximately $76,000 was recorded in discontinued operations in 2018. There were no discontinued operations during 2019. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the statements of operations for stock-based compensation arrangements during the year ended December 31, 2019 and December 31, 2018. Stock compensation expense was allocated between departments in continuing operations as follows (in thousands). Year ended December 31, 2019 December 31, 2018 Research and development $ 158 $ 205 General and administrative 667 982 Total $ 825 $ 1,187 Stock Options The Company granted options to purchase 658,285 and 756,086 of the Company’s common stock in 2019 and 2018, 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, 2019 December 31, 2018 Expected life (years) 5.5-6.1 5.5-6.0 Risk-free interest rate 1.6%-2.6% 2.7%-2.8% Volatility 70%-75% 70%-71% Dividend rate — % — % The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. These assumptions include the following estimates: • Expected life: The expected life of stock options represents the average of the contractual term of the options and the weighted-average vesting period, as permitted under the simplified method. The Company does not believe it is able to rely on historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term for use in estimating the fair value-based measurement of stock options. Therefore, it has opted to use the “simplified method” for estimating the expected term of options. • Risk-free interest rate: The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to liquidity. • Volatility: The estimated volatility rate based on the volatilities of the Company’s common stock together with comparable companies in the Company’s industry. • Dividend rate: The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Consequently, the Company used an expected dividend yield of zero The following table summarizes stock option and restricted stock unit transactions for the years ended December 31, 2019 and 2018 as issued under the 2014 Plan. Shares Available Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term for Grant Outstanding Share (in years) Balance at January 1, 2018 1,571,212 1,026,987 $ 9.99 7.94 Additional shares authorized 223,742 Shares allocated to grants of restricted stock units (245,588 ) Options granted (756,086 ) 756,086 $ 1.68 Options exercised — — — — Options canceled/forfeited 115,920 (115,920 ) $ 12.72 — Balance at December 31, 2018 909,200 1,667,153 $ 6.03 8.27 Additional shares authorized 223,742 Shares allocated to grants of restricted stock units (61,218 ) Options granted (658,285 ) 658,285 $ 1.77 Options exercised — — — — Options canceled/forfeited 202,321 (202,321 ) $ 6.99 — Balance at December 31, 2019 615,760 2,123,117 $ 4.62 7.87 Options vested at December 31, 2019 1,153,457 $ 6.91 7.24 Options vested and expected to vest at December 31, 2019 2,123,117 $ 4.62 7.87 The weighted-average grant date fair value of employee options granted was $1.14 and $1.08 per share for the year ended December 31, 2019 and December 31, 2018, respectively. At December 31, 2019 total unrecognized employee stock-based compensation was $1.1 million, which is expected to be recognized over the weighted-average remaining vesting period of 2.4 years. As of December 31, 2019, the outstanding stock options had an intrinsic value of $1.6 million. Restricted Stock Units There were 61,218 and 245,588 restricted stock units granted by the Company during the year ended December 31, 2019 and December 31, 2018, respectively, to employees, directors and consultants. The shares were 100% vested on the grant date and were valued based on the Company’s common stock price on the grant date, with approximately $132,000 and $434,000 of related stock-based compensation expense recognized during the year ended December 31, 2019 and December 31, 2018, respectively. 2014 Employee Stock Purchase Plan The Company’s board of directors and stockholders have adopted the 2014 Employee Stock Purchase Plan, or the ESPP. The ESPP has become effective, and the board of directors will implement commencement of offers thereunder in its discretion. A total of 27,967 shares of the Company’s common stock has been made available for sale under the ESPP. In addition, the ESPP provides for annual increases in the number of shares available for issuance under the plan on the first day of each year beginning in the year following the initial date that the board of directors authorizes commencement, equal to the least of: • 1.0% of the outstanding shares of the Company’s common stock on the first day of such year; • 55,936 shares; or • such amount as determined by the board of directors. As of December 31, 2019, there were no purchases by employees under this plan. Series D Warrants The Company issued 256,064 Series D Warrants in October 2015, which are exercisable into 586,182 shares of the Company’s common stock, with an exercise price of $12.30 and a term of five years expiring on October 15, 2020. The Company’s Series D Warrants contain standard anti-dilution provisions for stock dividends, stock splits, subdivisions, combinations and similar types of recapitalization events. They also contain a cashless exercise feature that provides for their net share settlement at the option of the holder in the event that there is no effective registration statement covering the continuous offer and sale of the warrants and underlying shares. The Company is required to comply with certain requirements to cause or maintain the effectiveness of a registration statement for the offer and sale of these securities. The Series D Warrant agreement further provides for the payment of liquidated damages at an amount per month equal to 1% of the aggregate VWAP of the shares into which each Series D Warrant is convertible into in the event that the Company is unable to maintain the effectiveness of a registration statement as described herein. The Company evaluated the registration payment arrangement stipulated in the terms of this securities agreement and determined that it is probable that the Company will maintain an effective registration statement and has therefore not allocated any portion of the proceeds to the registration payment arrangement. The Series D Warrant agreement specifically provides that under no circumstances will the Company be required to settle any Series D Warrant exercise for cash, whether by net settlement or otherwise. Accounting Treatment The Company accounts for the Series D Warrants in accordance with the guidance in ASC 815 Derivatives and Hedging. Other Common Stock Warrants As of December 31, 2019, the Company had 102,070 common stock warrants outstanding from the 2010/2012 convertible notes, with an exercise price of $24.35 and a term of 10 years expiring in November 2024. The Company also had outstanding 16,500 common stock warrants issued to the underwriter in the Company’s IPO, with an exercise price of $35.70 and a term of 10 years, expiring in November 2024.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Note 11. Income Taxes The geographical distribution of loss before income taxes are summarized below (in thousands). December 31, 2019 2018 United States $ (30,729 ) $ (11,830 ) Foreign (45 ) (11 ) Loss before income taxes $ (30,774 ) $ (11,841 ) Loss resulting from discontinued operations $ — $ (1,494 ) Taxes allocated to discontinued operations $ — $ — The provision for income tax benefit differs from the amount estimated by applying the statutory federal income tax rate to the operating loss from continuing operations due to the following (in thousands). December 31, 2019 2018 Tax on the loss before income tax expense computed at the federal statutory rate $ (6,463 ) $ (2,486 ) State tax (benefit) at statutory rate, net of federal benefit (1,691 ) (187 ) Foreign rate differential 10 2 Change in valuation allowance 6,696 4,143 Change in research and development credits (200 ) (99 ) Stock based compensation—ISOs 149 143 Change in fair value of warrants 1,461 (110 ) Change in fair value of contingent consideration 61 119 Gain on deconsolidation — (4 ) Disallowance of loss on discontinued operations — (426 ) Change in net operating loss true up (725 ) (590 ) Change in state rate true up 701 — Change in temporary difference true up — (456 ) Other 1 (49 ) 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, 2019 and 2018 (in thousands). December 31, 2019 2018 Non-current deferred tax assets: Federal and state net operating loss carryforwards $ 35,091 $ 28,532 Research and other credits 2,349 2,037 Reserves and accruals 77 52 Assets held for sale — 15 Fixed assets 71 67 Capital loss carryover 1,115 425 Stock based compensation 85 70 Lease liability 131 — Other deferred tax assets 196 542 Gross non-current deferred tax assets 39,115 31,740 Intangible assets (4,623 ) (4,062 ) Right-of-use assets (118 ) — Total non-current deferred tax liabilities (4,741 ) (4,062 ) Total deferred tax assets 34,374 27,678 Valuation allowance (34,374 ) (27,678 ) 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 $6.7 million from December 31, 2018 to December 31, 2019 primarily due to the generation of current year net operating losses, capital losses and research and development credits claimed. As of December 31, 2019, the Company had $150.5 million of federal, $82.5 million of state and approximately $299,000 of foreign net operating losses available to offset future taxable income. The federal net operating loss carryforwards begin to expire in 2020, the federal net operating loss carryforwards of $31.7 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. The Company adjusted its state net operating loss carryforward by $10.4 million for the year ended December 31, 2018. As of December 31, 2019, the Company also had $1.4 million of federal and approximately $916,000 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. 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 has not completed an updated analysis of 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 2019 and, as such, is not able at this time to determine the impact on the net operating loss (“NOL”) carryforwards, if any, as of the date of these consolidated financial statements. United States taxes and foreign withholding taxes have not been provided on undistributed earnings for certain non-United States subsidiaries as of December 31, 2019, 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, 2019 2018 Beginning balance $ 964 $ 854 Increase related to prior year tax positions 7 23 Decrease related to prior year tax positions (4 ) — Increase related to current year tax positions 144 87 Ending balance $ 1,111 $ 964 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 $1.1 million of unrecognized assets and liabilities related to uncertain tax positions as of December 31, 2019. 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, 2019 and December 31, 2018. As of December 31, 2019, unrecognized tax benefits of $1.1 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 and United Kingdom. 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 1999 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. The Jobs Act also establishes global intangible low-taxed income, or “GILTI,” provisions that impose a tax on foreign income in excess of a deemed return on intangible assets of foreign corporations. The Company’s accounting policy for the income tax effects of GILTI will be to recognize those taxes as expenses in the period incurred. In 2019, the Company’s foreign subsidiary realized a tested loss for the period and therefore, the Company did not have a GILTI inclusion for the year.

Net loss per share

Net loss per share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss per share	Note 12. Net loss per share Basic net loss per share is computed by dividing net loss by the weighted-average number of common stock actually outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common stock outstanding and dilutive potential common stock that would be issued upon the exercise of common stock warrants and options. For the years ended December 31, 2019 and 2018, the effect of issuing the potential common stock is anti-dilutive due to the net losses in those periods and the number of shares used to compute basic and diluted earnings per share are the same in each of those periods. The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of December 31, 2019 2018 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 2,123,117 1,667,153 Warrants issued in 2009 to purchase common stock — 1,851 Warrants issued to underwriter to purchase common stock 16,500 16,500 Series A warrants to purchase common stock — 485,121 Series C warrants to purchase common stock 118,083 118,083 Series D warrants to purchase common stock 586,162 586,162 2017 PIPE warrants 6,024,425 6,024,425 2018 PIPE warrants 513,617 513,617 Total 9,483,974 9,514,982

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	Note 13. 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. During the year ended December 31, 2019 the Company made matching contributions of approximately $37,000 to the 401(k) Plan. No contributions were made during the year ended December 31, 2018.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Note 14. Subsequent Events The Company has evaluated its subsequent events from December 31, 2019 through the date these consolidated financial statements were issued and has determined that there are no subsequent events requiring disclosure in these consolidated financial statements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the applicable rules and regulations of the Securities and Exchange Commission, or SEC. 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. Certain amounts from prior periods have been reclassified to conform to the current period presentation, including certain current liabilities within the Consolidated Balance Sheets and Consolidated Statements of Cash Flows, certain immaterial amounts within the Consolidated Statements of Operations, and the presentation of restricted stock units and the related expense within the Consolidated Statements of Stockholders’ Equity and Consolidated Statements of Cash Flows.
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 included in the financial statements include the valuation of deferred income tax assets, the valuation of financial instruments, stock-based compensation, value and life of acquired intangibles, and the valuation of contingent liabilities 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 one U.S. commercial bank. Cash and cash equivalents deposited with this commercial bank exceeded the Federal Deposit Insurance Corporation insurable limit at December 31, 2019 and 2018. The Company expects the maintenance of balances in excess of insurable limits will continue.
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 United States of America.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments, including its money market fund, purchased with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held in institutions in the U.S. and the U.K. and include deposits in a money market fund which was 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 insurance and short-term deposits. Prepaid expenses are initially recorded upon payment and are expensed as goods or services are received.
Intangible Assets	Intangible Assets Intangible assets with finite lives are amortized on a straight-line basis over their estimated useful lives of 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.
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.
Equity Method Investment	Equity Method Investment Equity method investments are equity securities in investees not controlled by the Company, but over which the Company has the ability to exercise significant influence. The Company’s equity method investment is measured at fair value minus impairment, if any, plus or minus the Company’s share of equity method investee income or loss. The Company’s equity method investment in Capnia, Inc. is classified as Minority interest investment in former subsidiary in the consolidated balance sheet as of December 31, 2018 and was initially measured at fair value. (See Note 9.) The Company sold its equity method investment in Capnia in September 2019.
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.
Research and Development	Research and Development Research and development costs are charged to operations as incurred. Research and development costs consist primarily of salaries and benefits, consultant fees, prototype expenses, certain facility costs and other costs associated with clinical trials, net of reimbursed amounts. 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. Certain research and development expenses are reported as discontinued operations. (See Note 9.)
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. The loss from discontinued operations is reported net of the related effect for income taxes in the statements of operations.
Convertible Preferred Stock and Other Hybrid Instruments	Convertible Preferred Stock and other Hybrid Instruments The Company’s convertible preferred stock was classified as permanent equity on its consolidated balance sheet in accordance with authoritative guidance for the classification and measurement of hybrid securities and distinguishing liability from equity instruments. The preferred stock is not redeemable at the option of the holder. Further, the Company evaluated its Series B Convertible Preferred Stock and determined that it is considered an equity host under ASC 815, Derivatives and Hedging
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 Series A, Series C, the 2017 PIPE Warrants and 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.
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 of the award. Stock options generally vest over four years. The Black-Scholes option-pricing model requires the use of highly subjective assumptions to estimate the fair value of stock-based awards. If we had made different assumptions, our stock-based compensation expense, net loss and net loss per share of common stock could have been significantly different. These assumptions include: • Expected volatility: The Company calculates the estimated volatility rate based the volatility of its common stock together with comparable companies in its industry. • Expected term: The Company does not believe it is able to rely on its historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term for use in estimating the fair value-based measurement of our options. Therefore, the Company has opted to use the “simplified method” for estimating the expected term of options. • 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 do 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 Accounting Standards	Recent Accounting Standards Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Codification (ASC) 842, Leases. Leases requires lessees to capitalize most lease obligations as right-of-use assets with a corresponding liability on the balance sheet. Leases are classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The guidance is effective for all public business entities and certain not-for-profit entities in fiscal years beginning after December 15, 2018, and for all other entities in fiscal years beginning after December 15, 2020. Early adoption is permitted. As the Company was an emerging growth company until December 31, 2019 and elected to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act, it adopted the standard as of January 1, 2019 on December 31, 2019. The Company adopted ASC 842 using the optional modified retrospective method and will not restate comparative periods. The Company has elected to apply the “practical expedient package”, which permits it to not reassess previous conclusions around lease identification, lease classification, and initial direct costs. Further, the Company will make an accounting policy election to exclude leases with terms of twelve months or less from the recognition requirements. The Company did not elect the use of the hindsight practical expedient. As a result of the adoption of the standard on January 1, 2019, the Company recognized lease liabilities based on the present value of the total fixed payments for its leases in the amount of approximately $322,000 and ROU assets of approximately $301,000 on its balance sheet. The adoption of the new standard did not have a material impact on the Company’s Statement of Operations or Cash Flows. In June 2018, the FASB issued ASU 2018-07, “ Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting” In August 2018, SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification Recently Issued Accounting Standards In August 2018, the FASB issued ASU 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement”. In December 2019, the FASB issued ASU 2019-12: “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”
Patents [Member]
Intangible Assets	Patent In March 2017, the Company completed the acquisition of Essentialis, Inc., a Delaware corporation, or Essentialis in accordance with the Merger Agreement by and between Soleno Therapeutics and Essentialis dated December 22, 2016. The merger transaction has been accounted for as an asset acquisition under the acquisition method of accounting and accordingly, the value of asset acquired in the amount of $22.0 million was assigned to the identifiable intangible asset relating to the patent for DCCR, which patent expires in June 2028.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 Total Level 1 Level 2 Level 3 Liabilities 2017 PIPE warrant liability $ 10,822 $ — $ — $ 10,822 2018 PIPE warrant liability 1,354 — — 1,354 Essentialis purchase price contingency liability 5,938 — — 5,938 Total common stock warrant and contingent consideration liability $ 18,114 $ - $ — $ 18,114 Fair Value Measurements at December 31, 2018 Total Level 1 Level 2 Level 3 Liabilities Series A warrant liability $ 49 $ 49 $ — $ — 2017 PIPE warrant liability 4,563 — — 4,563 2018 PIPE warrant liability 600 — — 600 Essentialis purchase price contingency liability 5,649 — — 5,649 Total common stock warrant and contingent consideration liability $ 10,861 $ 49 $ - $ 10,812
Summary of Changes in Fair Value of Level1 and Level 3 Financial Instruments	The following table sets forth a summary of the changes in the fair value of the Company’s Level 1 and Level 3 warrants, which are treated as liabilities (dollars in thousands). Series A Warrants Series C Warrants 2017 PIPE Warrants 2018 PIPE Warrants Purchase Price Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Number of Warrants Liability Contingent Liability Balance at January 1, 2019 485,121 $ 49 118,083 $ — 6,024,425 $ 4,563 513,617 $ 600 $ 5,649 Expiration of Series A Warrants (485,121 ) (49 ) — — — — — — — Change in value of Series C Warrants — — — — — — — — Change in value of 2017 PIPE Warrants — — — — — 6,259 — — — Change in value of 2018 PIPE Warrants — — — — — — — 754 — Change in value of contingent liability — — — — — — — — 289 Balance at December 31, 2019 — $ — 118,083 $ — 6,024,425 $ 10,822 513,617 $ 1,354 $ 5,938

Other Financial Statement Det_2

Other Financial Statement Details (Tables)	12 Months Ended
	Dec. 31, 2019
Other Financial Statement Details Disclosure [Abstract]
Schedule of Property and Equipment	Property and equipment are summarized in the following table (in thousands). December 31, 2019 December 31, 2018 Computer hardware $ 52 $ 67 Computer software — 2 Furniture and fixtures 1 23 Leasehold improvements — 13 53 105 Less accumulated depreciation and amortization (31 ) (93 ) Total $ 22 $ 12
Schedule of Intangible Assets	Intangible assets consist of the following (in thousands). December 31, 2019 December 31, 2018 Amount Accumulated Amortization Net Amount Amount Accumulated Amortization Net Amount Patents and merger costs $ 22,003 $ (5,478 ) $ 16,525 $ 22,003 $ (3,534 ) $ 18,469 Total $ 22,003 $ (5,478 ) $ 16,525 $ 22,003 $ (3,534 ) $ 18,469
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 2020 $ 1,944 2021 1,944 2022 1,944 2023 1,944 2024 1,944 2025 and thereafter 6,805 Total $ 16,525

Warrant Liabilities (Tables)

Warrant Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Series C Warrant [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The Company used the following inputs. December 31, 2019 December 31, 2018 Volatility 90 % 90 % Contractual term (years) 0.17 1.17 Expected dividend yield — % — % Risk-free rate 1.52 % 2.60 %
2017 PIPE Warrant Liability [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The following summarizes certain key assumptions used in estimating the fair values. December 31, 2019 December 31, 2018 Volatility 99 % 75 % Contractual term (years) 1.0 2.0 Expected dividend yield — % — % Risk-free rate 1.60 % 2.51 %
2018 PIPE Warrant Liability [Member]
Fair Value of Convertible Preferred Stock Warrant Liability	The following summarizes certain key assumptions used in estimating the fair values. December 31, 2019 December 31, 2018 Volatility 99 % 75 % Contractual term (years) 4.0 5.0 Expected dividend yield — % — % Risk-free rate 1.56 % 2.51 %

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of Components of Lease Expense	The components of lease expense during the year ended December 31, 2019 were as follows (in thousands): Operating lease cost: Operating lease cost $ 418 Sublease income (173 ) Total operating lease cost $ 245 Finance lease cost: Amortization of right-of-use assets $ 3 Interest on lease liabilities 1 Total finance lease cost $ 4
Schedule Of Supplemental Cash Flow Information Related To Leases	Supplemental cash flow information related to leases was as follows for the year ended December 31, 2019 (in thousands): Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 219 Operating cash flows from finance leases $ 1 Financing cash flows from finance leases $ 2 Right-of use assets obtained in exchange for lease obligations (noncash): Operating leases $ 484 Finance leases $ 27
Operating Lease and Finance Lease Liability Maturity	The following is a schedule by year of future maturities of the Company’s lease liabilities as of December 31, 2019 (in thousands): Operating Leases Finances Lease 2020 $ 336 $ 19 2021 143 8 Total lease payments 479 27 Less interest (34 ) (2 ) Total $ 445 $ 25

CoSense Joint Venture Agreeme_2

CoSense Joint Venture Agreement and Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
Components of Discontinued Operations	There were no assets or liabilities held for sale as of December 31, 2019, or December 31, 2018, after the deconsolidation of Capnia in October 2018, and no discontinued operations during the year ended December 31, 2019. The components of the Statements of Operations presented as Discontinued Operations during the year ended December 31, 2018 follow (in thousands). Product revenue $ 62 Cost of product revenue 32 Gross profit 30 Expenses Research and development 1,106 Sales and marketing 25 General and administrative 393 Total expenses 1,524 Operating loss (1,494 ) Net loss from discontinued operations $ (1,494 )

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Summary of Stock Based Compensation Expense	Stock compensation expense was allocated between departments in continuing operations as follows (in thousands). Year ended December 31, 2019 December 31, 2018 Research and development $ 158 $ 205 General and administrative 667 982 Total $ 825 $ 1,187
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, 2019 December 31, 2018 Expected life (years) 5.5-6.1 5.5-6.0 Risk-free interest rate 1.6%-2.6% 2.7%-2.8% Volatility 70%-75% 70%-71% Dividend rate — % — %
Summary of Stock Option and Restricted Stock Unit Transactions	The following table summarizes stock option and restricted stock unit transactions for the years ended December 31, 2019 and 2018 as issued under the 2014 Plan. Shares Available Number of Options Weighted- Average Exercise Price per Weighted Average Remaining Contractual Term for Grant Outstanding Share (in years) Balance at January 1, 2018 1,571,212 1,026,987 $ 9.99 7.94 Additional shares authorized 223,742 Shares allocated to grants of restricted stock units (245,588 ) Options granted (756,086 ) 756,086 $ 1.68 Options exercised — — — — Options canceled/forfeited 115,920 (115,920 ) $ 12.72 — Balance at December 31, 2018 909,200 1,667,153 $ 6.03 8.27 Additional shares authorized 223,742 Shares allocated to grants of restricted stock units (61,218 ) Options granted (658,285 ) 658,285 $ 1.77 Options exercised — — — — Options canceled/forfeited 202,321 (202,321 ) $ 6.99 — Balance at December 31, 2019 615,760 2,123,117 $ 4.62 7.87 Options vested at December 31, 2019 1,153,457 $ 6.91 7.24 Options vested and expected to vest at December 31, 2019 2,123,117 $ 4.62 7.87

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 2018 United States $ (30,729 ) $ (11,830 ) Foreign (45 ) (11 ) Loss before income taxes $ (30,774 ) $ (11,841 ) Loss resulting from discontinued operations $ — $ (1,494 ) Taxes allocated to discontinued operations $ — $ —
Provision for Income Tax Benefit by Applying Statutory Federal Income Tax Rate to Operating Loss from Continuing Operations	The provision for income tax benefit differs from the amount estimated by applying the statutory federal income tax rate to the operating loss from continuing operations due to the following (in thousands). December 31, 2019 2018 Tax on the loss before income tax expense computed at the federal statutory rate $ (6,463 ) $ (2,486 ) State tax (benefit) at statutory rate, net of federal benefit (1,691 ) (187 ) Foreign rate differential 10 2 Change in valuation allowance 6,696 4,143 Change in research and development credits (200 ) (99 ) Stock based compensation—ISOs 149 143 Change in fair value of warrants 1,461 (110 ) Change in fair value of contingent consideration 61 119 Gain on deconsolidation — (4 ) Disallowance of loss on discontinued operations — (426 ) Change in net operating loss true up (725 ) (590 ) Change in state rate true up 701 — Change in temporary difference true up — (456 ) Other 1 (49 ) 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, 2019 and 2018 (in thousands). December 31, 2019 2018 Non-current deferred tax assets: Federal and state net operating loss carryforwards $ 35,091 $ 28,532 Research and other credits 2,349 2,037 Reserves and accruals 77 52 Assets held for sale — 15 Fixed assets 71 67 Capital loss carryover 1,115 425 Stock based compensation 85 70 Lease liability 131 — Other deferred tax assets 196 542 Gross non-current deferred tax assets 39,115 31,740 Intangible assets (4,623 ) (4,062 ) Right-of-use assets (118 ) — Total non-current deferred tax liabilities (4,741 ) (4,062 ) Total deferred tax assets 34,374 27,678 Valuation allowance (34,374 ) (27,678 ) 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, 2019 2018 Beginning balance $ 964 $ 854 Increase related to prior year tax positions 7 23 Decrease related to prior year tax positions (4 ) — Increase related to current year tax positions 144 87 Ending balance $ 1,111 $ 964

Net loss per share (Tables)

Net loss per share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding	The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted-average shares outstanding because such securities have an antidilutive impact due to losses reported (in common stock equivalent shares). As of December 31, 2019 2018 Warrants issued to 2010/2012 convertible note holders to purchase common stock 102,070 102,070 Options to purchase common stock 2,123,117 1,667,153 Warrants issued in 2009 to purchase common stock — 1,851 Warrants issued to underwriter to purchase common stock 16,500 16,500 Series A warrants to purchase common stock — 485,121 Series C warrants to purchase common stock 118,083 118,083 Series D warrants to purchase common stock 586,162 586,162 2017 PIPE warrants 6,024,425 6,024,425 2018 PIPE warrants 513,617 513,617 Total 9,483,974 9,514,982

Going Concern and Management'_2

Going Concern and Management's Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 25, 2019	Dec. 31, 2019	Dec. 31, 2018
Liquidity And Managements Plans [Line Items]
Net loss		$ (30,774)	$ (13,335)
Accumulated deficit		(157,806)	(127,032)
Cash on hand		20,700
Net cash used in operating activities		$ (17,375)	$ (11,683)
Underwritten Public Offering [Member]
Liquidity And Managements Plans [Line Items]
Number of newly issued	12,841,667
Price per unit	$ 1.20
Net proceeds from shares issued	$ 14,500

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)BankSegment	Dec. 31, 2018	Jan. 01, 2019USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Number of commercial banks | Bank	1
Number of operating segments | Segment	1
Estimated useful life	11 years
Expected dividend yield	0.00%	0.00%
Accounting Standards Update 2016-02 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Present value of total fixed payments			$ 322,000
Right-of-use assets recognized			$ 301,000
Stock Options and Restricted Stock Units [Member]
Schedule Of Significant Accounting Policies [Line Items]
Vesting period	4 years
Stock Options [Member]
Schedule Of Significant Accounting Policies [Line Items]
Vesting period	4 years
Expected dividend yield	0.00%
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
Essentialis, Inc. [Member]
Schedule Of Significant Accounting Policies [Line Items]
Net intangible assets acquired	$ 22,000,000

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liabilities
Contingent liability for Essentialis purchase price	$ 5,938	$ 5,649
2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	10,822	4,563
2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,354	600
Series A Warrant Liability [Member]
Liabilities
Warrant liability		49
Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	18,114	10,861
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	10,822	4,563
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,354	600
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | Series A Warrant Liability [Member]
Liabilities
Warrant liability		49
Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	5,938	5,649
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability		49
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | Series A Warrant Liability [Member]
Liabilities
Warrant liability		49
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total common stock warrant and contingent consideration liability	18,114	10,812
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2017 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	10,822	4,563
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Liabilities | 2018 PIPE Warrant Liability [Member]
Liabilities
Warrant liability	1,354	600
Level 3 [Member] | Essentialis, Inc. [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Contingent liability for Essentialis purchase price	$ 5,938	$ 5,649

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 1 and Level 3 Financial Instruments (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)shares
Purchase price contingent liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 5,649
Change in value of liabilities	289
Balance at end of period	5,938
Series A 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	$ 49
Balance at the beginning of period, in shares | shares	485,121
Expiration of warrants, in shares | shares	(485,121)
Expiration of warrants	$ (49)
Series C Warrant [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period, in shares | shares	118,083
Balance at the end of period, in shares | shares	118,083
2017 PIPE Warrant Liability [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 4,563
Balance at the beginning of period, in shares | shares	6,024,425
Change in value of liabilities	$ 6,259
Balance at end of period	$ 10,822
Balance at the end of period, in shares | shares	6,024,425
2018 PIPE Warrant Liability [Member] | Common stock warrant liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of period	$ 600
Balance at the beginning of period, in shares | shares	513,617
Change in value of liabilities	$ 754
Balance at end of period	$ 1,354
Balance at the end of period, in shares | shares	513,617

Other Financial Statement Det_3

Other Financial Statement Details - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 53	$ 105
Less accumulated depreciation and amortization	(31)	(93)
Total	22	12
Computer Hardware [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	52	67
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		2
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1	23
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 13

Other Financial Statement Det_4

Other Financial Statement Details - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Other Financial Statement Details Disclosure [Abstract]
Depreciation expense	$ 11,000	$ 19,000
Amortization	$ 1,900,000	$ 1,900,000

Other Financial Statements Deta

Other Financial Statements Details - Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Amount	$ 22,003	$ 22,003
Accumulated Amortization	(5,478)	(3,534)
Net Amount	16,525	18,469
Patents and Merger Costs [Member]
Finite Lived Intangible Assets [Line Items]
Amount	22,003	22,003
Accumulated Amortization	(5,478)	(3,534)
Net Amount	$ 16,525	$ 18,469

Other Financial Statement Det_5

Other Financial Statement Details - Future Amortization Expense (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Net Amount	$ 16,525	$ 18,469
Patents And Trademark [Member]
Finite Lived Intangible Assets [Line Items]
2020	1,944
2021	1,944
2022	1,944
2023	1,944
2024	1,944
2025 and thereafter	6,805
Net Amount	$ 16,525

Warrant Liabilities - Additiona

Warrant Liabilities - Additional Information (Detail)	Apr. 30, 2015$ / shares	Mar. 05, 2015USD ($)$ / sharesshares	Jul. 31, 2015USD ($)shares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 19, 2018$ / sharesshares	Dec. 15, 2017$ / sharesshares
Class Of Warrant Or Right [Line Items]
Change in fair value of stock warrants				$ 6,964,000	$ (522,000)
Expected Dividend Yield [Member]
Class Of Warrant Or Right [Line Items]
Measurement input				0
Series A Warrants to Purchase Shares of Common Stock [Member] | IPO [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares				489,921
Exercise price of warrants exercised | $ / shares				$ 32.50
Warrants term				5 years
Series A Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Warrants exercised (in shares) | shares				4,800
Change in fair value of stock warrants					(49,000)
Warrant liability					49,000
Series B Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised | $ / shares		$ 32.50
Warrants exercised (in shares) | shares		117,902
De-recognition of warrant liability		$ 6,700,000
Proceeds from exercise of warrants		$ 3,800,000
Series C Warrant [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares				118,083
Exercise price of warrants exercised | $ / shares	$ 31.25	$ 31.25
Tender offer expiration date	Mar. 5, 2020	Mar. 5, 2020
Proceeds from issuance of common stock under tender offer			$ 6,000
Warrants cashless exercised (in shares) | shares			181
Aggregate VWAP (percent)				1.00%
Warrant liability				$ 0
Series C Warrant [Member] | Common Stock [Member]
Class Of Warrant Or Right [Line Items]
Issuance of shares upon cashless exercise warrants (in shares) | shares			181
2017 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares							6,024,425
Exercise price of warrants exercised | $ / shares							$ 2
Change in fair value of stock warrants				6,300,000
Warrant liability				$ 10,822,000	4,563,000
Warrant issuance description				The 2017 PIPE Warrants were issued on December 15, 2017 in the 2017 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2017 PIPE Offering, and entitle the holders to purchase 6,024,425 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2017 PIPE Warrants and terminating at the earlier of December 15, 2020 or 30 days following positive Phase III results for the DCCR tablet in PWS.
Fair value of estimated warrants				$ 10,800,000
2017 PIPE Warrant Liability to Purchase Common Stock [Member] | Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised | $ / shares				$ 1.72
2018 PIPE Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Number of common stock purchased upon issuance of warrants | shares						513,617
Exercise price of warrants exercised | $ / shares						$ 2
Change in fair value of stock warrants				$ 754,000
Warrant liability				$ 1,354,000	$ 600,000
Warrant issuance description				The 2018 PIPE Warrants were issued on December 19, 2018 in the 2018 PIPE Offering, pursuant to a Warrant Agreement with each of the investors in the 2018 PIPE Offering, and entitle the holders to purchase 513,617 shares of the Company’s common stock at an exercise price equal to $2.00 per share, subject to adjustment as discussed below, at any time commencing upon issuance of the 2018 PIPE Warrants and terminating on December 21, 2023.
Fair value of estimated warrants				$ 1,400,000
2018 PIPE Warrant Liability [Member] | Minimum [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants exercised | $ / shares				$ 2

Warrant Liabilities - Fair Valu

Warrant Liabilities - Fair Value of Convertible Preferred Stock Warrant Liability (Detail)	Dec. 31, 2019	Dec. 31, 2018
Expected Dividend Yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0
Series C Warrant [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.90	0.90
Series C Warrant [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	2 months 1 day	1 year 2 months 1 day
Series C Warrant [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0152	0.0260
2017 PIPE Warrant Liability [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.99	0.75
2017 PIPE Warrant Liability [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	1 year	2 years
2017 PIPE Warrant Liability [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0160	0.0251
2018 PIPE Warrant Liability [Member] | Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.99	0.75
2018 PIPE Warrant Liability [Member] | Contractual Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement term	4 years	5 years
2018 PIPE Warrant Liability [Member] | Risk-free Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.0156	0.0251

Leases - Additional Information

Leases - Additional Information (Detail)	1 Months Ended			12 Months Ended
	Sep. 30, 2020USD ($)	Nov. 30, 2019USD ($)	Jul. 31, 2019USD ($)ft²	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Lessee Lease Description [Line Items]
Sublease income				$ 173,000
Future minimum commitment under non-cancelable operating lease				219,000
Operating lease right-of-use assets				398,000
Finance lease right-of-use assets				24,000
Current operating lease liabilities				305,000
Current finance lease liabilities				$ 17,000
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]				us-gaap:OtherLiabilitiesCurrent
Long-term operating lease liabilities				$ 139,000
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]				us-gaap:OtherLiabilitiesNoncurrent
Long-term finance lease liabilities				$ 8,000
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]				us-gaap:OtherLiabilitiesNoncurrent
Rent expense					$ 323,000
Sublease income					$ 277,000
Finance lease, weighted-average remaining lease term				1 year 4 months 24 days
Finance lease, discount rate				10.00%
Operating lease, weighted-average remaining lease term				1 year 4 months 24 days
Operating lease, discount rate				10.00%
Redwood City, California [Member]
Lessee Lease Description [Line Items]
Area of operating lease | ft²			6,368
Operating lease, description				the Company executed a non-cancellable lease agreement for 6,368 square feet of new space in Redwood City, California, which began in September 2019 and expires in May 2021.
Operating lease beginning date			2019-09
Operating lease, expiration			2021-05
Payment to acquire office furniture under operating lease			$ 1
Future minimum commitment under non-cancelable operating lease		$ 29,000
Redwood City, California [Member] | Forecast [Member]
Lessee Lease Description [Line Items]
Future minimum commitment under non-cancelable operating lease	$ 30,000
Capnia Inc Joint Venture [Member] | Redwood City, California [Member]
Lessee Lease Description [Line Items]
Sublease income				$ 65,000

Leases - Schedule of Components

Leases - Schedule of Components of Lease Expense (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 418
Sublease income	(173)
Total operating lease cost	245
Amortization of right-of-use assets	3
Interest on lease liabilities	1
Total finance lease cost	$ 4

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 219
Operating cash flows from finance leases	1
Financing cash flows from finance leases	2
Right-of use assets obtained in exchange for lease obligations (noncash):
Operating leases	484
Finance leases	$ 27

Leases - Schedule Of Future Mat

Leases - Schedule Of Future Maturities (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Operating Leases
2020	$ 336
2021	143
Total lease payments	479
Less interest	(34)
Total	445
Finances Lease
2020	19
2021	8
Total lease payments	27
Less interest	(2)
Total	$ 25

CoSense Joint Venture Agreeme_3

CoSense Joint Venture Agreement and Discontinued Operations - Additional Information (Detail)	Oct. 16, 2018shares	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)$ / shares
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current period gain recognized			$ 2,000,000
Minority interest investment in former subsidiary			978,000				$ 978,000
Loss from minority interest investment						$ (478,000)	(160,000)
Gain in minority interest investment		$ 33,000,000
Loss from discontinued operations							(1,494,000)
Stock-based compensation expense						825,000	1,300,000
Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense						0	76,000
CoSense, NFI and Serenz [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, current			0			0	0
Assets held for sale, long-term			0			0	0
Liabilities held for sale, current			0			0	0
Liabilities held for sale, long-term			$ 0			0	0
Loss from discontinued operations						$ 0	$ (1,494,000)
Sinon Investments LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total purchase price		$ 500,000,000
Capnia Inc Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Negotiated price per share | $ / shares				$ 1
Percentage of ownership interest				47.00%
Number of shares owned | shares				1,480,000
Percentage of discount for lack of control				0.23
Loss from minority interest investment					$ 511,000,000
Capnia Inc Joint Venture [Member] | Sinon Investments LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of ownership interest		47.00%
Minority interest investment in former subsidiary		$ 467,000,000			467,000,000
OAHL [Member] | Capnia Inc Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minority interest investment in former subsidiary		$ 0			$ 0
OAHL [Member] | Capnia Inc Joint Venture [Member] | Corporate Joint Venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment threshold requirement								$ 2,200,000
Negotiated price per share | $ / shares								$ 1
Investment threshold requirement stock issuance				$ 1,200,000				$ 1,200,000
Issuance of common stock (shares) | shares	1,690,322
Percentage of ownership interest	53.00%

CoSense Joint Venture Agreeme_4

CoSense Joint Venture Agreement and Discontinued Operations - Components of Income of Discontinued Operations (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Expenses
Net loss from discontinued operations		$ (1,494,000)
CoSense, NFI and Serenz [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Product revenue		62,000
Cost of product revenue		32,000
Gross profit		30,000
Expenses
Research and development		1,106,000
Sales and marketing		25,000
General and administrative		393,000
Total expenses		1,524,000
Operating loss		(1,494,000)
Net loss from discontinued operations	$ 0	$ (1,494,000)

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Oct. 25, 2019	Dec. 19, 2018	Mar. 07, 2017	Jan. 27, 2017	Oct. 31, 2015	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 29, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Convertible preferred stock, shares authorized							10,000,000	10,000,000
Stock-based compensation expense							$ 825,000	$ 1,300,000
Expected dividend yield							0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)							$ 1.14	$ 1.08
Future stock-based compensation for unvested employee options granted and outstanding							$ 1,100,000
Stock options outstanding, intrinsic value							$ 1,600,000
Number of shares available for issuance under the plan on the first day of each year							44,658,054	31,755,169
Series D Warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants (in dollars per share)					$ 12.30
Number of common stock purchased upon issuance of warrants					586,182
Warrants outstanding (in shares)					256,064
Warrants term					5 years
Warrants expiration date					Oct. 15, 2020
Liquidated damages amount percent of VWAP (percent)					1.00%
Warrants to Purchase Stock [Member] | 2010 and 2012 Convertible Promissory Notes [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants (in dollars per share)							$ 24.35
Warrants outstanding (in shares)							102,070
Warrants term							10 years
Warrants expiration period							2024-11
Underwriter [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of warrants (in dollars per share)							$ 35.70
Warrants outstanding (in shares)							16,500
Warrants term							10 years
Warrants expiration period							2024-11
Discontinued Operations, Held-for-sale [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense							$ 0	$ 76,000
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership interest of voting rights of all classes of stock (percent)							10.00%
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period							4 years
Number of shares available for grant							615,760	909,200	1,571,212
Income tax benefits recognized from stock-based compensation							$ 0	$ 0
Number of options granted							658,285	756,086
Expected dividend yield							0.00%
Future stock-based compensation, requisite service period							2 years 4 months 24 days
Stock Options [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair market value							110.00%
Stock Options [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option							10 years
ISOs [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual term of option							5 years
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense							$ 132,000	$ 434,000
Stock units granted							61,218	245,588
Vesting percentage							100.00%
Underwritten Public Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from issuance of common stock	$ 14,500,000
Number of newly issued	12,841,667
Price per unit	$ 1.20
Shares issued upon exercise of underwriters options	1,675,000
Net proceeds from issuance of public offering	$ 14,500,000
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant							27,967
Percentage of outstanding stock maximum							1.00%
Number of shares available for issuance under the plan on the first day of each year							55,936
Equity Unit Purchase Agreements [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of newly issued		10,272,375
Price per unit		$ 1.61
Gross Proceeds from issuance of units		$ 16,500,000
Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of newly issued							12,841,667
Common Stock [Member] | Equity Unit Purchase Agreements [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrant to call common stock		0.05
Exercise price of warrants (in dollars per share)		$ 2
Number of common stock purchased upon issuance of warrants		513,617
Aspire Capital Fund, LLC [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum commitment under stock purchase agreement				$ 17,000,000
Purchase agreement term				30 months
Proceeds from issuance of common stock				$ 2,000,000
Essentialis, Inc. [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued in acquisition (shares)			3,783,388
Indemnification claims period			1 year
Contingent consideration potential additional shares issuable if milestones are reached (shares)						903,367
Maximum total common stock issuable in acquisition (in shares)			4,867,422
Essentialis, Inc. [Member] | Indemnification Claims [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued in acquisition (shares)			180,667
Essentialis, Inc. [Member] | Earnout Payments [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum potential cash earnout payments			$ 30,000,000
Series B Convertible Preferred Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Convertible preferred stock, shares authorized							13,780	13,780
Preferred stock shares issued							0	0		13,780
Preferred stock, shares outstanding							0	0

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Based Compensation Expense (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 825,000	$ 1,300,000
Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	825,000	1,187,000
Research and Development [Member] | Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	158,000	205,000
General and Administrative [Member] | Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock compensation expense	$ 667,000	$ 982,000

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	1.60%	2.70%
Risk-free interest rate, Maximum	2.60%	2.80%
Volatility, Minimum	70.00%	70.00%
Volatility, Maximum	75.00%	71.00%
Dividend rate	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	5 years 6 months	5 years 6 months
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	6 years 1 month 6 days	6 years

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option and Restricted Stock Unit Transactions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options [Member]
Shares Available for Grant
Options Available, Beginning balance	909,200	1,571,212
Options Available, Additional shares authorized	223,742	223,742
Options Available, Granted	(658,285)	(756,086)
Options Available, Exercised	0	0
Options Available, Canceled/Forfeited	202,321	115,920
Options Available, Ending balance	615,760	909,200	1,571,212
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance	1,667,153	1,026,987
Options granted	658,285	756,086
Options exercised	0	0
Options canceled/forfeited	(202,321)	(115,920)
Ending balance	2,123,117	1,667,153	1,026,987
Options vested at end of period (shares)	1,153,457
Options vested and expected to vest at end of period (shares)	2,123,117
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 6.03	$ 9.99
Options granted (in dollars per share)	1.77	1.68
Options exercised (in dollars per share)	0	0
Options canceled/forfeited (in dollars per share)	6.99	12.72
Ending balance (in dollars per share)	4.62	$ 6.03	$ 9.99
Options vested at end of period (in dollars per share)	6.91
Options vested and expected to vest at end of period (in dollars per share)	$ 4.62
Weighted Average Remaining Contractual Term
Options outstanding at end of period	7 years 10 months 13 days	8 years 3 months 7 days	7 years 11 months 8 days
Options vested at end of period	7 years 2 months 26 days
Options vested and expected to vest at end of period	7 years 10 months 13 days
Restricted Stock Units [Member]
Shares Available for Grant
Options Available, Shares allocated to grants of restricted stock units	(61,218)	(245,588)

Income Taxes - Schedule of Geog

Income Taxes - Schedule of Geographical Distribution of Loss before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States	$ (30,729)	$ (11,830)
Foreign	(45)	(11)
Loss before income taxes	$ (30,774)	(11,841)
Loss resulting from discontinued operations		$ (1,494)

Income Taxes - Provision for In

Income Taxes - Provision for Income Tax Benefit by Applying Statutory Federal Income Tax Rate to Operating Loss from Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Tax on the loss before income tax expense computed at the federal statutory rate	$ (6,463)	$ (2,486)
State tax (benefit) at statutory rate, net of federal benefit	(1,691)	(187)
Foreign rate differential	10	2
Change in valuation allowance	6,696	4,143
Change in research and development credits	(200)	(99)
Stock based compensation—ISOs	149	143
Change in fair value of warrants	1,461	(110)
Change in fair value of contingent consideration	61	119
Gain on deconsolidation		(4)
Disallowance of loss on discontinued operations		(426)
Change in net operating loss true up	(725)	(590)
Change in state rate true up	701
Change in temporary difference true up		(456)
Other	$ 1	$ (49)

Income Taxes - Significant Comp

Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Non-current deferred tax assets:
Federal and state net operating loss carryforwards	$ 35,091	$ 28,532
Research and other credits	2,349	2,037
Reserves and accruals	77	52
Assets held for sale		15
Fixed assets	71	67
Capital loss carryover	1,115	425
Stock based compensation	85	70
Lease liability	131
Other deferred tax assets	196	542
Gross non-current deferred tax assets	39,115	31,740
Intangible assets	(4,623)	(4,062)
Right-of-use assets	(118)
Total non-current deferred tax liabilities	(4,741)	(4,062)
Total deferred tax assets	34,374	27,678
Valuation allowance	$ (34,374)	$ (27,678)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Increase (decrease) in valuation allowance	$ 6,700,000
Unrecognized assets and liabilities related to uncertain tax positions	1,100,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0	$ 0
Unrecognized tax benefit offset by change in valuation allowance	1,100,000
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	500,000
U.S. Federal Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	150,500,000
Operating loss carryforwards, carried forward indefinitely	31,700,000
U.S. Federal Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards	1,400,000
State Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	82,500,000	$ 10,400,000
State Tax Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards	916,000
Foreign Tax Authority [Member] | Her Majesty's Revenue and Customs (HMRC) [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 299,000

Income Taxes - Summary of Gross

Income Taxes - Summary of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Beginning balance	$ 964	$ 854
Increase related to prior year tax positions	7	23
Decrease related to prior year tax positions	(4)
Increase related to current year tax positions	144	87
Ending balance	$ 1,111	$ 964

Net loss per share - Schedule o

Net loss per share - Schedule of Potentially Dilutive Securities Outstanding Excluded from Computations of Diluted Weighted-Average Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	9,483,974	9,514,982
Warrants Issued to 2010/2012 Convertible Note Holders to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	102,070	102,070
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	2,123,117	1,667,153
Warrants Issued in 2009 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		1,851
Underwriter [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	16,500	16,500
Series A Warrants to Purchase Shares of Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding		485,121
Series C Warrant to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	118,083	118,083
Series D Warrant 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	586,162	586,162
2017 PIPE Warrant Liability [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	6,024,425	6,024,425
2018 PIPE Warrant Liability [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computations of diluted weighted-average shares outstanding	513,617	513,617

Defined Contribution Plan - Add

Defined Contribution Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Matching contribution by Company	$ 37,000	$ 0