Trevi Therapeutics (TRVI) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 10, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Registrant Name	TREVI THERAPEUTICS, INC.
Entity Central Index Key	0001563880
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Trading Symbol	TRVI
Entity Common Stock, Shares Outstanding		25,846,577
Entity Shell Company	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Entity File Number	001-38886
Entity Tax Identification Number	45-0834299
Entity Address, Address Line One	195 Church Street
Entity Address, Address Line Two	14th Floor
Entity Address, City or Town	New Haven
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06510
City Area Code	203
Local Phone Number	304-2499
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 29,318	$ 45,001
Prepaid expenses and other current assets	1,389	1,268
Total current assets	30,707	46,269
Deferred offering costs	419	284
Operating lease right-of-use asset	156	227
Security deposits and other non-current assets	248	248
Property, equipment and leasehold improvements, net	66	103
Total assets	31,596	47,131
Current liabilities:
Accounts payable	2,233	2,016
Accrued expenses	3,314	3,426
Term loan - current portion	4,083
Term loan derivative liability - current portion	167
Operating lease liability - current portion	116	113
Total current liabilities	9,913	5,555
Term loan - long term portion	10,245	13,954
Term loan derivative liability - long term portion		196
Operating lease liability - long term portion	58	144
Total liabilities	20,216	19,849
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock: $0.001 par value; 5,000,000 shares authorized at September 30, 2021 and December 31, 2020; no shares issued or outstanding at September 30, 2021 or December 31, 2020.
Common stock: $0.001 par value; 200,000,000 shares authorized at September 30, 2021 and December 31, 2020; and 21,621,524 and 18,546,786 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively.	22	19
Additional paid-in capital	183,755	174,240
Accumulated deficit	(172,397)	(146,977)
Total stockholders’ equity	11,380	27,282
Total liabilities and stockholders’ equity	$ 31,596	$ 47,131

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	21,621,524	21,621,524
Common Stock, Shares, Outstanding	18,546,786	18,546,786

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses:
Research and development	$ 4,718	$ 4,828	$ 16,805	$ 15,768
General and administrative	2,229	2,416	7,398	7,528
Total operating expenses	6,947	7,244	24,203	23,296
Loss from operations	(6,947)	(7,244)	(24,203)	(23,296)
Other (expense) income:
Change in fair value of term loan derivative liability	(5)		29
Other expense			(375)
Interest income	2	3	7	174
Interest expense	(303)	(148)	(893)	(148)
Total other (expense) income, net	(306)	(145)	(1,232)	26
Loss before income taxes	(7,253)	(7,389)	(25,435)	(23,270)
Income tax (expense) benefit	(2)	11	15	35
Net loss	$ (7,255)	$ (7,378)	$ (25,420)	$ (23,235)
Basic and diluted net loss per common share outstanding	$ (0.34)	$ (0.41)	$ (1.25)	$ (1.30)
Weighted average common shares used in net loss per share attributable to common stockholders, basic and diluted	21,607,979	18,134,886	20,390,852	17,935,865

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Lincoln Park Capital Fund, LLC [Member]	Common Stock [Member]	Common Stock [Member]Lincoln Park Capital Fund, LLC [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Lincoln Park Capital Fund, LLC [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2019	$ 54,545		$ 18		$ 168,746		$ (114,219)
Beginning Balance (in shares) at Dec. 31, 2019			17,834,570
Stock-based compensation	1,907				1,907
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	2,364				2,364
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			466,758
Issuance of common stock from exercise of stock options	34				34
Issuance of common stock from exercise of stock options (in shares)			18,343
Issuance of common stock from Employee Stock Purchase Plan	3				3
Issuance of common stock from Employee Stock Purchase Plan (in share)			1,397
Net loss	(23,235)						(23,235)
Ending Balance at Sep. 30, 2020	35,618		$ 18		173,054		(137,454)
Ending Balance (in shares) at Sep. 30, 2020			18,321,068
Beginning Balance at Dec. 31, 2019	54,545		$ 18		168,746		(114,219)
Beginning Balance (in shares) at Dec. 31, 2019			17,834,570
Net loss	(32,800)
Ending Balance at Dec. 31, 2020	27,282		$ 19		174,240		(146,977)
Ending Balance (in shares) at Dec. 31, 2020			18,546,786
Beginning Balance at Jun. 30, 2020	40,037		$ 18		170,095		(130,076)
Beginning Balance (in shares) at Jun. 30, 2020			17,851,152
Stock-based compensation	588				588
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	2,364				2,364
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			466,758
Issuance of common stock from exercise of stock options	7				7
Issuance of common stock from exercise of stock options (in shares)			3,158
Net loss	(7,378)						(7,378)
Ending Balance at Sep. 30, 2020	35,618		$ 18		173,054		(137,454)
Ending Balance (in shares) at Sep. 30, 2020			18,321,068
Beginning Balance at Jun. 30, 2020	40,037		$ 18		170,095		(130,076)
Beginning Balance (in shares) at Jun. 30, 2020			17,851,152
Ending Balance at Sep. 30, 2021	11,380		$ 22		183,755		(172,397)
Ending Balance (in shares) at Sep. 30, 2021			21,621,524
Beginning Balance at Dec. 31, 2020	27,282		$ 19		174,240		(146,977)
Beginning Balance (in shares) at Dec. 31, 2020			18,546,786
Stock-based compensation	2,003				2,003
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	7,123		$ 3		7,120
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			2,895,518
Issuance of common stock from Employee Stock Purchase Plan	17				17
Issuance of common stock from Employee Stock Purchase Plan (in share)			9,132
Issuance of common stock to Lincoln Park Capital Fund		$ 375				$ 375
Issuance of common stock to Lincoln Park Capital Fund, shares				170,088
Net loss	(25,420)						(25,420)
Ending Balance at Sep. 30, 2021	11,380		$ 22		183,755		(172,397)
Ending Balance (in shares) at Sep. 30, 2021			21,621,524
Beginning Balance at Jun. 30, 2021	17,736		$ 21		182,857		(165,142)
Beginning Balance (in shares) at Jun. 30, 2021			21,459,498
Stock-based compensation	540				540
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees	359		$ 1		358
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			162,026
Net loss	(7,255)						(7,255)
Ending Balance at Sep. 30, 2021	$ 11,380		$ 22		$ 183,755		$ (172,397)
Ending Balance (in shares) at Sep. 30, 2021			21,621,524

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating activities:
Net loss	$ (7,255)	$ (7,378)	$ (25,420)	$ (23,235)	$ (32,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation			38	34
Change in fair value of term loan derivative liability			(29)
Accretion/accrual of term loan discounts and debt issuance costs			442	68
Other expense related to transaction with Lincoln Park Capital Fund, LLC			375
Stock-based compensation	540	588	2,003	1,907
Changes in operating assets and liabilities:
Prepaid expenses and other current assets			(122)	323
Accounts payable			216	(341)
Accrued expenses and other liabilities			(220)	1,168
Net cash used in operating activities			(22,717)	(20,076)
Investing activities:
Purchases of property, equipment and leasehold improvements				(27)
Net cash used in investing activities				(27)
Financing activities:
Proceeds from term loan				14,000
Payments of financing costs of term loan			(68)	(53)
Proceeds from at-the-market sales, net of commissions			7,505	2,442
Proceeds from exercises of stock options				34
Proceeds from employee stock purchase plan			17	3
Payments of offering costs			(420)	(343)
Net cash provided by financing activities			7,034	16,083
Net decrease in cash and cash equivalents			(15,683)	(4,020)
Cash and cash equivalents at beginning of period			45,001	57,313	57,313
Cash and cash equivalents at end of period	$ 29,318	$ 53,293	$ 29,318	$ 53,293	$ 45,001

Nature of the Business

Nature of the Business	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Trevi Therapeutics, Inc. (“Trevi” or the “Company”) is a clinical-stage biopharmaceutical company focused on the development and commercialization of the investigational therapy Haduvio (nalbuphine ER) to treat serious neurologically mediated conditions. The Company is currently developing Haduvio for the treatment of chronic pruritus associated with prurigo nodularis and chronic cough in patients with idiopathic pulmonary fibrosis (“IPF”). The Company is also developing Haduvio in levodopa-induced dyskinesia (“LID”) in patients with Parkinson’s disease. These conditions share a common pathophysiology that is mediated through opioid receptors in the central and peripheral nervous systems. Due to nalbuphine’s mechanism of action as a modulator of opioid receptors, the Company believes Haduvio has the potential to be effective in treating each of these conditions. Haduvio is an oral extended-release formulation of nalbuphine. Nalbuphine is a mixed κ-opioid receptor agonist and μ-opioid receptor antagonist that has been approved and marketed as an injectable for pain indications for more than 20 years in the United States (“U.S.”) and Europe. The κ- and μ-opioid receptors are known to be critical mediators of itch, cough and certain movement disorders. Nalbuphine’s mechanism of action also mitigates the risk of abuse associated with μ-opioid agonists because it antagonizes or blocks, the μ-opioid receptor. Parenteral nalbuphine is not classified as a controlled substance in the U.S. and most of Europe. Liquidity In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) The Company’s Condensed Consolidated Financial Statements have been prepared on a going concern basis, which contemplates the continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has financed its operations primarily through private placements of convertible preferred stock and convertible notes prior to its initial public offering (“IPO”), borrowings under its prior term loan facility, proceeds from its IPO and concurrent private placement completed in May 2019, sales of its common stock pursuant to the at-the-market Sales Agreement (the “ATM Sales Agreement”) (Note 7) with SVB Leerink LLC that the Company entered into in June 2020 and the term loan facility with Silicon Valley Bank (“SVB”) that the Company entered into in August 2020. The Company has incurred recurring losses since inception, including net losses of $25.4 million for the nine months ended September 30, 2021 and $32.8 million for the year ended December 31, 2020. As of September 30, 2021, the Company had cash and cash equivalents of $29.3 million compared to $45.0 million of cash and cash equivalents as of December 31, 2020. The Company has incurred losses and negative cash flows from operations and had an accumulated deficit of $172.4 million as of September 30, 2021. The Company expects to continue to incur losses for the foreseeable future. As of November 10, 2021, the date of issuance of these Condensed Consolidated Financial Statements, the Company believes that its cash and cash equivalents as of September 30, 2021, together with the proceeds from the Company’s October 2021 private placements (Note 12), will not be sufficient to fund its operating expenses and capital expenditure requirements for 12 months from the date of issuance of these Condensed Consolidated Financial Statements. The Company plans to seek to address this condition by raising additional capital to finance its operations. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing. Therefore, it is not considered probable, as defined in ASU No. 2014-15, that the Company’s plans to raise additional capital will alleviate the substantial doubt regarding its ability to continue as a going concern. To execute its business plans, the Company will need substantial funding to support its continuing operations and pursue its growth strategy. Until such time that the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through the sale of common stock in public offerings and/or private placements, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may not be able to obtain financing when needed on acceptable terms or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or abandon its product development programs or commercialization efforts, which could adversely affect its business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Basis of Presentation The accompanying unaudited interim Condensed Consolidated Financial Statements for the three and nine months ended September 30, 2021 and 2020 included herein, have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim information. Certain prior year balances have been reclassified to conform to the current year presentation. Such reclassifications did not affect loss from operations or net loss. Certain information and footnote disclosures typically prepared in accordance with GAAP have been condensed or omitted pursuant to SEC rules and regulations. The accompanying unaudited Condensed Consolidated Financial Statements and notes should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (the “Annual Report on Form 10-K”). The accompanying Condensed Consolidated Financial Statements include the accounts of Trevi Therapeutics, Inc. and its wholly-owned subsidiary Trevi Therapeutics Limited. Intercompany balances and transactions have been eliminated. All amounts presented are in thousands of dollars, except share and per share amounts, unless noted otherwise. The Company has evaluated events occurring subsequent to September 30, 2021 for potential recognition or disclosure in the Condensed Consolidated Financial Statements. Refer to Note 12 for disclosure related to events occurring subsequent to September 30, 2021. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of the expenses during the reporting periods. Significant estimates and assumptions reflected in these Condensed Consolidated Financial Statements include, but are not limited to, the recognition of research and development (“R&D”) expenses, the valuation of stock-based awards and the valuation allowance of deferred tax assets resulting from net operating losses. In addition, management’s assessment of the Company’s ability to continue as a going concern involves the estimation of the amount and timing of future cash inflows and outflows. On an ongoing basis, management evaluates its estimates in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. The inputs into the Company’s estimates also considered the economic implications of the COVID-19 pandemic on the Company’s estimates. Unaudited Interim Financial Information The accompanying interim Condensed Consolidated Balance Sheet as of September 30, 2021 and the Condensed Consolidated Statements of Operations, the Condensed Consolidated Statements of Stockholders’ Equity and the Condensed Consolidated Statements of Cash Flows for the three and nine months ended September 30, 2021 and 2020 are unaudited. The unaudited interim Condensed Consolidated Financial Statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the Company’s opinion, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statements of its financial position as of September 30, 2021 and the results of its operations and its cash flows for the three and nine months ended September 30, 2021 and 2020. The results for the three and nine months ended September 30, 2021 and 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2021 or any other interim period or any future year or period. Cash Equivalents The Company classifies short-term, highly liquid investments with an original term of three months or less at the date of purchase as cash equivalents. Fair Value Measurements The Company’s financial instruments have consisted of cash and cash equivalents, other current assets, accounts payable, accrued expenses, term loans and term loan derivative liability (Note 6). Fair specific point in time, based on relevant market information. The carrying amounts of cash and cash equivalents, other current assets, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of the short - term nature of those instruments. The carrying amount of the term loan approximates its fair value due to its floating market-based interest rate. The term loan derivative liability is recorded at fair value , which is estimated utilizing a probability-weighted cash flow approach (Note 6). Current accounting guidance defines fair value, establishes a framework for measuring fair value in accordance with Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures Level 1—Observable inputs—quoted prices in active markets for identical assets and liabilities. Level 2—Observable inputs other than the quoted prices in active markets for identical assets and liabilities—such as quoted prices for similar instruments, quoted prices for identical or similar instruments in inactive markets or other inputs that are observable or can be corroborated by observable market data. Level 3—Unobservable inputs—includes amounts derived from valuation models where one or more significant inputs are unobservable and require the company to develop relevant assumptions. The following table summarizes the financial assets and financial liabilities measured at fair value on a recurring basis and the basis for that measurement, by level within the fair value hierarchy (Note 6): Level 1 Level 2 Level 3 September 30, 2021 Financial assets carried at fair value: Money market funds (1) $ 28,325 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 167 December 31, 2020 Financial assets carried at fair value: Money market funds (1) $ 44,095 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 196 (1) The following table represents a roll-forward of the fair value of Level 3 instruments (significant unobservable inputs): September 30, 2021 December 31, 2020 Financial liabilities Balance at beginning of period $ 196 $ 187 Change in fair value of term loan derivative liability (29 ) 9 Balance at end of period $ 167 $ 196 Property, Equipment and Leasehold Improvements Property, equipment and leasehold improvements (consisting of furniture, computer and office equipment and leasehold improvements) are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets (three years for computer equipment, five years for furniture and office equipment and the shorter of the term of the lease or useful life for leasehold improvements). Impairment of Long-Lived Assets ASC 360, Property, Plant and Equipment, Foreign Currency Transactions The Company, at times, contracts with vendors and consultants outside of the U.S., resulting in liabilities denominated in foreign currency. The transactions are recorded in U.S. dollars on the transaction dates and any currency fluctuation through the payment date is recorded as currency gains or losses in the Condensed Consolidated Statements of Operations. Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded in stockholders’ equity as a reduction of additional paid-in capital generated as a result of the financing. Should the planned equity financing no longer be considered probable of being consummated, the deferred offering costs are expensed immediately as a charge to operating expenses. Research and Development Expenses All of the Company’s research and development expenses consist of expenses incurred in connection with the development of Haduvio. These expenses include certain payroll and personnel expenses, including stock-based compensation, consulting costs, contract manufacturing costs and fees paid to clinical research organizations (“CROs”) to conduct certain research and development activities on the Company’s behalf. The Company does not allocate its costs by each indication for which it is developing Haduvio, as a significant amount of the Company’s development activities broadly support all indications. In addition, several of the Company’s departments support the Company’s Haduvio drug candidate development program and the Company does not identify internal costs for each potential indication. The Company expenses both internal and external research and development expenses as they are incurred. Accrued Research and Development Expenses The Company has entered into agreements with CROs, contract manufacturing organizations (“CMOs”) and other companies that provide services in connection with the Company’s research and development activities. The Company’s research and development accruals are estimated based on the level of services performed, progress of the studies, including the phase or completion of events and contracted costs. The estimated costs of research and development provided, but not yet invoiced, are included in accrued expenses on the Condensed Consolidated Balance Sheets. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to CROs, CMOs and other companies under these arrangements in advance of the performance of the related services are recorded as prepaid expenses or as other non-current assets, as applicable, and are recognized as expenses as the goods are delivered or the related services are performed. Patent Costs All patent-related costs in connection with filing and prosecuting patent applications are expensed to general and administrative expense as incurred, as recoverability of such expenditures is uncertain. Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees and non-employees for consultancy services in accordance with ASC 718, Stock Compensation The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. For performance-based vesting, the fair value is also recognized on a straight-line basis over the requisite service period based on whether the performance conditions are probable. The Company reassesses the probability of achieving the performance conditions at each reporting date. Forfeitures are accounted for as they occur. Estimating the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require analysis and judgment to develop. Expected Term—The expected term assumption represents the weighted average period that the stock-based awards are expected to be outstanding. The Company has elected to use the “simplified method” for estimating the expected term of the options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. Expected Volatility—For all stock options granted to date, the volatility data was estimated based on a study of publicly traded industry peer companies. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. Expected Dividend—The Black-Scholes valuation model calls for a single expected dividend yield as an input. The Company currently has no history or expectation of paying cash dividends on its common stock. Risk-Free Interest Rate—The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. Prior to the Company’s IPO in May 2019, the estimated fair value of the common stock underlying the Company’s stock options was determined at each grant date by the Company’s board of directors, with input from management. All options to purchase shares of common stock were intended to be exercisable at a price per share not less than the per share fair value of the Company’s common stock underlying those options on the date of grant. In the absence of a public trading market for the Company’s common stock prior to the Company’s IPO in May 2019, on each grant date, the Company developed an estimate of the fair value of its common stock based on the information known to the Company on the date of grant, upon a review of any recent events and their potential impact on the estimated fair value per share of the common stock and in part on input from an independent third-party valuation. As is provided for in Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”), the Company generally relied on valuations for up to twelve months unless the Company had experienced a material event that would have affected the estimated fair value of its common stock. The valuations of the Company’s common stock performed prior to the Company’s IPO in May 2019, were determined in accordance with the guidelines outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “Practice Aid”). The methodology to determine the fair value of common stock included estimating the fair value of the enterprise using a market approach, which estimates the fair value of the Company by including an estimation of the value of the business based on the guideline public companies under a number of different scenarios. The assumptions used to determine the estimated fair value of the Company’s common stock were based on numerous objective and subjective factors, combined with management judgment, including external market conditions affecting the pharmaceutical and biotechnology industry and trends within the industry; the Company’s stage of development; the rights, preferences and privileges of the Company’s convertible preferred stock relative to those of the Company’s common stock; the prices at which the Company sold shares of convertible preferred stock; the Company’s financial condition and operating results, including the Company’s levels of available capital resources; the progress of the Company’s research and development efforts; the stage of development and business strategy; the equity market conditions affecting comparable public companies; the general U.S. market conditions and the lack of marketability of the Company’s common stock. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In accordance with the Practice Aid, the Company considered the following methods: • Option Pricing Method (“OPM”)—The OPM treats common stock and convertible preferred stock as call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the various holders of a company’s securities changes. Under this method, the common stock has value only if the funds available for distribution to stockholders exceed the value of the liquidation preferences at the time of a liquidity event, such as a strategic sale or merger. The common stock is modeled as a call option on the underlying equity value at a predetermined exercise price. In the model, the exercise price is based on a comparison with the total equity value rather than, as in the case of a regular call option, a comparison with a per share stock price. Thus, common stock is considered to be a call option with a claim on the enterprise at an exercise price equal to the remaining value immediately after the convertible preferred stock liquidation preference is paid. The OPM uses the Black-Scholes option-pricing model to price the call options. This model defines the securities’ fair values as functions of the current fair value of a company and uses assumptions, such as the anticipated timing of a potential liquidity event and the estimated volatility of the equity securities. • Probability Weighted Expected Return Method (“PWERM”)—Under the PWERM methodology, the fair value of common stock is estimated based upon an analysis of future values for the company, assuming various outcomes. The common stock value is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes available as well as the rights of each class of stock. The future value of the common stock under each outcome is discounted back to the valuation date at an appropriate risk-adjusted discount rate and probability weighted to arrive at an indication of value for the common stock. • Hybrid Method—The hybrid method is a PWERM where the equity value in one of the scenarios is calculated using an OPM. In the hybrid method used by the Company, it considered an IPO as the other potential future liquidity event. The equity value for the IPO scenario was determined using the guideline public company (“GPC”), method under the market approach. The relative probability of the IPO scenario was determined based on an analysis of market conditions at the time and expectations as to the timing and likely prospects of the IPO at each valuation date. In application of the GPC method, the Company considered publicly traded companies in the biopharmaceutical industry that had a similar profile to the Company’s as well as recently completed IPOs as indicators of estimated future value in an IPO. The Company then discounted that future value back to the valuation date at an appropriate discount rate. In determining the estimated fair value of the Company’s common stock prior to Company’s IPO in May 2019, the board of directors considered the fact that the Company’s stockholders could not freely trade the Company’s common stock in the public markets. Accordingly, the Company’s board of directors applied discounts to reflect the lack of marketability of common stock based on the weighted-average expected time to liquidity. The estimated fair value of the Company’s common stock at each grant date reflected a non-marketability discount partially based on the anticipated likelihood and timing of a future liquidity event. Subsequent to the completion of the Company’s IPO in May 2019, the fair value of the Company’s common stock has been determined based on the closing price of the Company’s common stock as reported on the date of grant on the primary stock exchange on which the Company’s common stock is traded. Income Taxes The Company accounts for income taxes using the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The Company applies the provisions of ASC 740, Income Taxes Leases Under ASC 842, Leases Operating lease right-of-use assets and operating lease liabilities are determined and recognized on the commencement date of the lease based on the present value of lease payments over the term of the lease. As the Company’s leases do not provide an implicit rate within the lease, the Company uses its incremental borrowing rate, which is updated periodically, based on information available at the commencement date of the lease to determine the present value of the lease payments. Basic and Diluted Net Loss per Common Share Basic and diluted net loss per common share outstanding is determined by dividing net loss by the weighted average common shares outstanding during the period. For all periods presented, shares issuable upon exercise of stock options have been excluded from the calculation because their effects would be anti-dilutive. Therefore, the weighted average common shares used to calculate both basic and diluted net loss per share are the same for each of the periods presented. Recently Adopted Accounting Pronouncements On January 1, 2021, the Company adopted ASU No. 2019-12- Income Taxes (Topic 740) Recently Issued Accounting Pronouncements There have been no new accounting pronouncements during the nine months ended September 30, 2021, which could be expected to materially impact the Company’s Condensed Consolidated Financial Statements.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2021
Prepaid Expense And Other Assets Current [Abstract]
Prepaid Expenses and Other Current Assets	3. Prepaid expenses and other current assets consisted of the following: September 30, 2021 December 31, 2020 Prepaid corporate insurance $ 1,007 $ 562 Prepaid other and other current assets 234 373 Prepaid R&D costs 148 333 Total prepaid expenses and other current assets $ 1,389 $ 1,268

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	4. Leases Effective March 1, 2013, the Company entered into a lease for office space in New Haven, CT and commencing March 1, 2018, the Company entered into the First Amendment to the lease (collectively, the “Office Space Lease”). The leased space is approximately 5,600 square feet and the Office Space Lease has a term of 60 months. The Office Space Lease requires monthly payments ranging from approximately $10 to $11 through February 1, 2023 and provides for two designated months of free rent. The incremental borrowing rate used on the Office Space Lease was 13.0%. The right-of-use asset also includes any lease payments related to initial direct costs and prepayments and excludes lease incentives. Lease expense is recognized on a straight-line basis over the lease term. The Company had no new leases during the nine months ended September 30, 2021. The Office Space Lease is an operating lease and the remaining term as of September 30, 2021 is approximately 1.5 years September 30, 2021 December 31, 2020 Assets: Operating lease right-of-use asset $ 156 $ 227 Liabilities: Operating lease liabilities, current portion 116 113 Operating lease liabilities, long term portion 58 144 Total operating lease liabilities $ 174 $ 257 Future minimum lease payments from September 30, 2021 until the expiration of the operating leases are as follows: 2021 $ 34 2022 131 2023 24 Total lease payments 189 Less: imputed discount rate (15 ) Carrying value of operating lease liabilities $ 174 Lease expense under operating leases, including leases of office equipment, was $29 and $31 for the three months ended September 30, 2021 and 2020, respectively and $90 and $93 for the nine months ended September 30, 2021 and 2020, respectively. Lease payments made in the three months ended September 30, 2021 and 2020 were $35 and $23, respectively and $104 and $103 for the nine months ended September 30, 2021 and 2020, respectively, with such amounts reflected in the Condensed Consolidated Statements of Cash Flows in operating activities.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following: September 30, 2021 December 31, 2020 Accrued R&D projects $ 1,660 $ 1,754 Accrued compensation and benefits 960 954 Accrued consulting and professional fees 624 560 Accrued other 70 158 Total accrued expenses $ 3,314 $ 3,426

Debt

Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt	6. Debt SVB Term Loan On August 13, 2020 (the “Effective Date”), the Company entered into a loan and security agreement (the “SVB Loan Agreement”) with SVB, as lender, pursuant to which SVB provided a term loan to the Company in the original principal amount of $14.0 million (the “SVB Term Loan”). The Company may use the proceeds from the SVB Term Loan for working capital and general corporate purposes. The SVB Term Loan bears interest at a floating rate per annum equal to the greater of (A) the prime rate plus 1.00% and (B) 4.25%. If SVB receives evidence satisfactory to it that the Company has (i) received positive data for the Phase 2b/3 clinical trial of Haduvio sufficient to advance Haduvio into a second Phase 3 clinical trial for prurigo nodularis and (ii) raised sufficient financing to fund such Phase 3 clinical trial and the Company’s operations, (together, the “Phase 3 Event”), the interest rate under the SVB Term Loan will be adjusted to a floating rate equal to the greater of (A) the prime rate plus 3.00% and (B) 6.25% (see term loan derivative liability discussion below). On the first business day of each month, the Company will be required to make monthly interest payments and commencing on March 1, 2022, the Company will be required to repay the SVB Term Loan in 24 consecutive installments of principal plus monthly payments of accrued interest. All outstanding principal and accrued and unpaid interest under the SVB Term Loan and all other outstanding obligations with respect to the SVB Term Loan are due and payable in full on February 1, 2024. The SVB Loan Agreement permits voluntary prepayment of all, but not less than all, of the SVB Term Loan, subject to a prepayment premium. Such prepayment premium would be 3.00% of the principal amount of the SVB Term Loan if prepaid prior to the first anniversary of the Effective Date, 2.00% of the principal amount of the SVB Term Loan if prepaid on or after the first anniversary of the Effective Date but prior to the second anniversary of the Effective Date and 1.00% of the principal amount of the SVB Term Loan if prepaid on or after the second anniversary of the Effective Date but prior to February 1, 2024. Upon repayment in full of the SVB Term Loan, the Company will be required to pay a final payment fee equal to $1.2 million. The SVB Term Loan and related obligations under the SVB Loan Agreement are secured by substantially all of the Company’s properties, rights and assets, except for its intellectual property (which is subject to a negative pledge under the SVB Loan Agreement). On July 6, 2021, the Company and SVB entered into a First Amendment (the “Loan Amendment”) to the SVB Loan Agreement. The Loan Amendment modifies the conditions under which the Company is required to cash collateralize all outstanding amounts owed to SVB under the . Under the to raise by June 30, 2022 sufficient net proceeds from the sale of equity securities to finance its planned second phase 3 clinical trial of Haduvio for prurigo nodularis and its ongoing operations (each a “Milestone Condition”), the Company will be required to deposit unrestricted and unencumbered cash equal to 100% of the principal amount of the SVB Term Loan then outstanding in a cash collateral account with SVB, which can be used by SVB to prepay the SVB Term Loan at any time. . The Company would also have been required to cash collateralize all outstanding amounts owed to SVB under the SVB Loan Agreement if it did not raise at least $15.0 million in net proceeds from the sale of equity securities during the period from June 1, 2021 through October 31, 2021. The Company satisfied this equity funding condition through a combination of equity issuances under the Company’s ATM Sales Agreement and two private placements, which took place in October 2021 (see Note 12). The SVB Loan Agreement contains customary representations, warranties, events of default and covenants. The occurrence and continuation of an event of default could cause interest to be charged at the rate that is otherwise applicable plus 5.00% (unless SVB elects to impose a smaller increase) and would provide SVB with the right to accelerate all obligations under the SVB Loan Agreement and exercise remedies against the Company and the collateral securing the SVB Term Loan and other obligations under the SVB Loan Agreement, including foreclosure against assets securing the SVB Term Loan and other obligations under the SVB Loan Agreement, including the Company’s cash. In August 2020, in connection with the SVB Term Loan, the Company paid $57 in financing costs to a third party, which were recorded as deferred charges and will be amortized over the life of the SVB Term Loan using the effective interest method. In connection with the Loan Amendment, the Company paid $68 in financing costs to a third party, which were recorded as deferred charges and will be amortized over the remaining life of the SVB Term Loan using the effective interest method. Amortization of these deferred financing charges totaled $11 and $22 for the three and nine months ended September 30, 2021, respectively and is included in interest expense in the Company’s Condensed Consolidated Statements of Operations. The unamortized deferred charges totaled $93 and $48 at September 30, 2021 and December 31, 2020, respectively and are included as a direct reduction of the carrying value of the term loan payable on the Company’s Condensed Consolidated Balance Sheets. In August 2020, in connection with the execution of the SVB Loan Agreement, the Company paid $27 in financing costs to SVB, which were recorded as loan discounts. These loan discounts are included as a reduction in the balance of the term loan payable on the Company’s Condensed Consolidated Balance Sheets and will be accreted over the life of the SVB Term Loan using the effective interest method. Accretion of these loan discounts totaled $3 and $8 for the three and nine months ended September 30, 2021 and is included in interest expense in the Company’s Condensed Consolidated Statements of Operations. At September 30, 2021 and December 31, 2020 , the loan discount-financing costs balance was $ 15 and $ 23 , respectively. In connection with the SVB Loan Agreement, the Company is obligated to pay a final payment fee of $1.2 million upon repayment in full of the SVB Term Loan. The final payment fee is being accrued over the life of the SVB Term Loan using the effective interest method and is included as an increase in the balance of the term loan payable on the Company’s Condensed Consolidated Balance Sheets. At September 30, 2021 and December 31, 2020, $538 and $183 was accrued for the final payment fee, respectively. Upon the occurrence of the Phase 3 Event, the interest rate on the SVB Term Loan will increase by 2.00% (the “Contingent Interest Rate Increase”) as described above. The Contingent Interest Rate Increase represents a free-standing financial instrument. Accordingly, the Company accounted for the Contingent Interest Rate Increase as a derivative under ASC 815, Derivatives and Hedging Fair values of the term loan derivative liability are estimated utilizing a probability-weighted cash flow approach, including variables for the timing of the Phase 3 Event and other probability estimates. For the fair value calculations of the term loan derivative liability at September 30, 2021 and December 31, 2020, significant inputs included the Contingent Interest Rate Increase of 2.00%, a discount rate of 12.0% and the SVB Term Loan maturity date of February 1, 2024. As of September 30, 2021, the Company had outstanding borrowings of $14.0 million under the SVB Term Loan and the term loan payable balance as presented on the Company’s Condensed Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020 was comprised as shown below. September 30, 2021 December 31, 2020 Principal outstanding under term loan $ 14,000 $ 14,000 Term loan discount-interest (102 ) (158 ) Term loan discount-unamortized deferred charges (93 ) (48 ) Term loan discount-financing costs, net of accretion (15 ) (23 ) Term loan-final payment fee 538 183 14,328 13,954 Less current portion 4,083 - Term loan payable, non-current $ 10,245 $ 13,954 Interest expense on the SVB Term Loan, which is comprised of interest payments, accretion and amortization of term loan discounts and the accrual of the final payment fee, is shown below for the three and nine months ended September 30, 2021 and 2020, respectively. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Interest payments $ 152 $ 80 $ 451 $ 80 Accretion and amortization of term loan discounts 33 4 87 4 Accrual of the final payment fee 118 64 355 64 $ 303 $ 148 $ 893 $ 148

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Stockholders Equity Note [Abstract]
Stockholders' Equity	7. As of September 30, 2021 and December 31, 2020, the Company had reserved September 30, 2021 December 31, 2020 Shares of common stock reserved for future issuance under the 2012 Stock Incentive Plan 761,553 921,824 Shares of common stock reserved for future issuance under the 2019 Stock Incentive Plan 3,299,064 2,396,922 Shares of common stock reserved for future issuance under the 2019 Employee Stock Purchase Plan 503,789 327,454 4,564,406 3,646,200 Private Placements On October 5, 2021 and October 18, 2021, the Company issued common stock and warrants to purchase common stock in two private placements (the “October 2021 Private Placements”). Refer to Note 12 for additional information. At-the-Market Offering In June 2020, the Company entered into the ATM Sales Agreement, under which the Company may issue and sell shares of its common stock, from time to time, having an aggregate offering price of up to $12.0 million. Sales of common stock under the ATM Sales Agreement may be made by any method that is deemed an “at-the-market” offering as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. The Company is not obligated to make any sales of its common stock under the ATM Sales Agreement. The Company began making sales pursuant to the ATM Sales Agreement in July 2020. During the three and nine months ended September 30, 2021, the Company issued and sold an aggregate of 162,026 and 2,895,518 shares of common stock, respectively, for gross proceeds of $0.3 million and $7.7 million, respectively, before deducting estimated commissions and allocated fees of less than $0.1 million and $0.6 million, respectively. As of September 30, 2021, the Company had issued and sold an aggregate of 3,583,394 shares of common stock for gross proceeds of $10.9 million, before deducting estimated commissions and allocated fees of $0.8 million. Under the terms of the October 2021 Private Placements, as described in Note 12, the Company agreed not to issue or sell additional shares under the ATM Sales Agreement on or prior to January 4, 2022. Equity Purchase Agreement On June 18, 2021, the Company entered into a common stock purchase agreement (“LPC Purchase Agreement”) with Lincoln Park Capital Fund, LLC (“Lincoln Park”). The LPC Purchase Agreement provides that, subject to the terms and conditions therein, the Company has the right, but not the obligation, to sell, at its discretion, to Lincoln Park up to $15.0 million of shares of common stock over a 24-month period commencing on July 23, 2021. In addition, under the LPC Purchase Agreement, the Company issued 170,088 shares of common stock to Lincoln Park as consideration for Lincoln Park’s commitment to purchase shares of the Company’s common stock under the LPC Purchase Agreement. The purchase price per share of the shares sold will be based on the market prices prevailing immediately preceding the time of sale as computed under the LPC Purchase Agreement. Lincoln Park has covenanted not to cause or engage in any manner whatsoever, any direct or indirect short selling or hedging of the Company’s common stock. The agreement may be terminated by the Company at any time, at its sole discretion, without any additional cost or penalty. Under the terms of the October 2021 Private Placements, the Company agreed to not issue or sell additional shares under the LPC Purchase Agreement on or prior to April 6, 2023. Stock-Based Awards In April 2019, the Company’s board of directors adopted the 2019 Stock Incentive Plan (the “2019 Plan”), which became effective on May 7, 2019. The 2019 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors are eligible to receive awards under the 2019 Plan. The 2019 Plan is administered by the Company’s board of directors. Awards may be made under the 2019 Plan for up to such number of shares of the Company’s common stock as is equal to the sum of i) 1,578,947 shares; plus ii) the number of shares (up to 1,157,894 shares) equal to the number of shares of the Company’s common stock subject to outstanding awards under the 2012 Stock Incentive Plan (the “2012 Plan”) that expire, terminate or are otherwise cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right; plus iii) an annual increase to be added on the first day of each fiscal year, beginning with 2020 and continuing through 2029, equal to the lesser of (a) 2,105,623 shares of common stock, (b) 4 % of the number of outstanding shares of the Company’s common stock on such date and (c) an amount determined by the Company’s board of directors. Effective January 1, 2021 and January 1, 2020, respectively, t he number of shares reserved for issuance under the 2019 Plan increased pursuant to the terms of the 2019 Plan by an additional 741,871 shares and 713,383 shares, equal to 4 % of the Company’s then-outstanding c ommon s tock . The 2012 Plan was adopted by the Company’s board of directors and stockholders. The 2012 Plan provides for the issuance of stock-based awards to the Company’s employees, officers, directors, consultants and advisors. The Company’s board of directors administers the 2012 Plan. Options granted under the 2019 Plan and the 2012 Plan have a maximum term of ten years. Options granted to employees, officers and non-employees generally vest over four years based on varying vesting schedules that primarily include: 25% vesting on the first anniversary date of grant and the balance ratably over the next 36 months or vesting in equal monthly or quarterly installments over four ye ars. 1,249,653 shares of common stock were granted and outstanding, net of cancellations, under the 2019 Plan. As of September 30, 2021 and December 31, 2020, options to purchase 761,553 and 921,824 shares of common stock, respectively, were granted and outstanding, net of cancellations, under the 2012 Plan. In April 2019, the Company’s board of directors adopted a resolution effective on May 7, 2019, that no further stock options or other equity-based awards may be granted under the 2012 Plan. In February 2021, the compensation committee of the Company’s board of directors approved the grant of stock options with performance-based vesting (“PSOs”) to employees of the Company. The PSOs granted in February 2021, vest based on the timing and successful results of the Company’s PRISM or CANAL clinical trials. A summary of the Company’s combined stock option activity for the 2019 Plan and the 2012 Plan for the nine months ended September 30, 2021 is as follows: Number of Option Shares Weighted Average Exercise Price Outstanding as of December 31, 2020 2,171,477 $ 5.62 Granted 1,474,875 $ 2.94 Forfeited (420,241 ) $ 4.39 Expired (176,931 ) $ 6.30 Exercised — $ — Outstanding as of September 30, 2021 3,049,180 $ 4.45 Options exercisable as of September 30, 2021 1,304,796 $ 5.02 Options unvested as of September 30, 2021 1,744,384 $ 4.03 In April 2019, the Company’s board of directors adopted the 2019 Employee Stock Purchase Plan (the “2019 ESPP”), which became effective on May 7, 2019. The 2019 ESPP is administered by the Company’s board of directors. The total number of shares of common stock that may be issued under the 2019 ESPP Plan was 518,918 All of the Company’s employees are eligible to participate in the 2019 ESPP, provided that: • such person is customarily employed by the Company for more than 20 hours a week and for more than five months in a calendar year; • such person has been employed by the Company for at least three months prior to enrolling in the 2019 ESPP; and • such person was an employee of the Company on the first day of the applicable offering period under the 2019 ESPP. The following table summarizes the classifications of stock-based compensation expenses for the 2012 Plan, the 2019 Plan and the 2019 ESPP recognized in the Condensed Consolidated Statements of Operations: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expense $ 169 $ 82 $ 593 $ 259 General and administrative expense 371 506 1,410 1,648 $ 540 $ 588 $ 2,003 $ 1,907

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	8. During the three and nine months ended September 30, 2021 and 2020, the Company maintained a full valuation allowance on deferred tax assets. The amounts recorded for income tax (expense) benefit during the three and nine months ended September 30, 2021 and 2020, were to align the Company’s estimates for its state research and development credits in each given year.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	9 . The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net loss $ (7,255 ) $ (7,378 ) $ (25,420 ) $ (23,235 ) Weighted average common shares used in net loss per share attributable to common stockholders, basic and diluted 21,607,979 18,134,886 20,390,852 17,935,865 Basic and diluted net loss per common share outstanding $ (0.34 ) $ (0.41 ) $ (1.25 ) $ (1.30 ) The Company’s potential dilutive securities, which include stock options, have been excluded from the computation of diluted net loss per share attributable to common stockholders whenever the effect of including them would be to reduce the net loss per share. In periods where there is a net loss, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The common shares underlying stock options, based on stock options outstanding as of September 30, 2021 and 2020, were excluded from the calculations of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect.

Collaborative and Licensing Agr

Collaborative and Licensing Agreements	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborative and Licensing Agreements	10 . The Company enters into collaborative and licensing agreements with pharmaceutical companies to in-license, develop, manufacture and/or market products that fit within its business strategy. Endo Pharmaceuticals Inc. In May 2011, the Company entered into an agreement with Penwest Pharmaceuticals Co. (“Penwest”) (subsequently merged into its parent, Endo Pharmaceuticals Inc. (“Endo”)) for an exclusive worldwide sublicensable license under certain patent rights and know-how controlled by Penwest to develop and commercialize products incorporating nalbuphine hydrochloride in any formulation, including an extended-release formulation such as Haduvio, in all fields and for any use. Under the license agreement, the Company paid Penwest a non-creditable, minimal non-refundable upfront license fee. The Company may also become obligated to make milestone payments to Endo of $0.3 million, which would become due upon the successful completion of the first Phase 3 clinical trial of a licensed product candidate, such as the Phase 2b/3 PRISM trial and $0.8 million, which would become due upon the marketing approval of a licensed product in the U.S. and to pay mid-single-digit royalties based on net sales of the licensed products by the Company, its affiliates and sublicensees. In addition, the Company is obligated to pay Endo a low-to-mid double-digit percentage of certain income it receives from sublicensees, based on the date of the definitive agreement under which the sublicense was granted. The Company’s royalty obligation with respect to each licensed product in each country commences upon the first commercial sale of the product in that country and extends until the later of the expiration, unenforceability or invalidation of the last valid claim of any licensed patent or application covering the licensed product in the country or the expiration of 10 years after the first commercial sale of the licensed product in the country, which period is referred to as the royalty term. Upon the expiration of the royalty term for a product in a country , the Company is thereafter obligated to pay a low single-digit know-how and trademark royalty. Under the agreement, the Company has granted Endo a non-exclusive, royalty-free (except for pass-through payments to third parties), sublicensable license under its relevant patent rights to use any improvement the Company makes to Endo’s controlled release technology for any product other than the products under which it is licensed by Endo. Both the Company and Endo have the right to terminate the agreement if the other party materially breaches the agreement and fails to cure the breach within specified cure periods. Endo also has the right to terminate in the event the Company undergoes specified bankruptcy, insolvency or liquidation events. The Company has the right to terminate the agreement at its convenience at any time on 180 days’ notice to Endo. Additionally, if the Company or any of the Company’s sublicensees challenge the validity or enforceability of any licensed patent rights covering a licensed product and that challenge is not terminated within a specified period, the agreement will immediately terminate and all licenses granted under the agreement shall be revoked. Upon termination of the agreement, the Company must transfer to Endo all regulatory filings and approvals relating to the development, manufacture or commercialization of the licensed products and all trademarks, other than the Company’s corporate trademarks, then being used in connection with the licensed products. If the agreement is terminated under certain specified circumstances, the Company will be deemed to have granted Endo a perpetual, royalty-free (except for pass-through payments to third parties), worldwide, exclusive, sublicensable license, under any improvements the Company made to the licensed know-how and any related patent rights the Company has to manufacture and commercialize the licensed products. Exclusive License Agreement with Rutgers In November 2018, the Company entered into an agreement with Rutgers, The State University of New Jersey (“Rutgers”) for an exclusive, worldwide, sublicensable license under certain patent rights controlled by Rutgers and for a non-exclusive, worldwide, sublicensable license under certain know-how controlled by Rutgers, in each case to develop and commercialize products incorporating nalbuphine for any human or animal use. Upon entering into the license agreement, the Company paid Rutgers a minimal upfront license issue fee, which was recorded as R&D expense in 2018 and agreed to pay Rutgers a minimal annual license fee. The Company may become obligated to make milestone payments to Rutgers in the aggregate of up to $0.3 million based on the achievement of certain clinical, regulatory and sales milestones. The Company has also agreed to pay Rutgers a low single-digit percentage of certain income it receives from sublicensees and to pay tiered low single-digit royalties based on net sales of licensed products by the Company, its affiliates and sublicensees. The Company’s royalty obligation with respect to each licensed product in each country commences on the date of the first commercial sale of the licensed product in that country following receipt of marketing approval and extends until the later of the date of expiration, unenforceability or invalidation of the last valid claim of any licensed patent or patent application covering the licensed product in the country and 10 years after the first commercial sale of the first licensed product sold anywhere in the world, which period is referred to as the royalty term. Upon the expiration of the royalty term for a licensed product in a country, the license granted to the Company under the agreement shall become perpetual, fully paid-up, irrevocable and royalty-free in such country. The royalty is subject to reduction in certain circumstances. In June 2021, the Company entered into an amendment with Rutgers to extend the deadline to commence a clinical trial on nalbuphine ER for LID to December 31, 2022. The Company paid a minimal fee related to this amendment, which was recorded as R&D expense during the second quarter of 2021. Restructuring Agreement with MentiNova, LLC In November 2018, concurrent with the signing of the agreement with Rutgers described above, the Company entered into a restructuring agreement with MentiNova, LLC (“MentiNova”), for the purchase of specified information and know-how, specified contractual rights and benefits and all books and records of MentiNova related thereto (collectively, the “Acquired Assets”). Upon entering into the license agreement, the Company paid MentiNova an aggregate upfront payment of $0.1 million, which was recorded as R&D expense in 2018, subject to specified closing adjustments. The Company may become obligated to make milestone payments to MentiNova in the aggregate of up to $1.2 million based on the achievement of certain clinical and regulatory milestones as well as tiered low single-digit royalties based on net sales of products containing nalbuphine as the sole active pharmaceutical ingredient that are developed by the Company using the Acquired Assets or the intellectual property licensed to the Company under the Rutgers agreement described above (the “Rutgers IP”) for indications that are within the scope of the Rutgers IP. The royalty is subject to reduction in certain circumstances.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 1 . Commitments and Contingencies A significant portion of the Company’s development activities are outsourced to third parties under agreements, including with CROs and contract manufacturers in connection with clinical trials and production of clinical trial materials. These arrangements may require the Company to pay termination costs to the third parties for reimbursement of costs and expenses incurred in the event of the orderly termination of contractual services. The Company also has commitments under lease and licensing agreements (Note 4 and Note 10).

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events Financing On October 5, 2021, the Company issued and sold to an initial investor in a private placement priced at-the-market under Nasdaq rules, (i) 2,373,201 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 4,746,402 shares of the Company’s common stock, and (ii) pre-funded warrants to purchase up to an aggregate of 4,926,069 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 9,852,138 shares of the Company’s common stock. Each share of the Company’s common stock and accompanying common stock warrants were sold together at a combined price of $1.62, and each pre-funded warrant and accompanying common stock warrants were sold together at a combined price of $1.619, for gross proceeds of approximately $11.8 million. Each pre-funded warrant has an exercise price of $0.001 per share, became exercisable immediately upon issuance and will continue to be exercisable until exercised in full. Of the accompanying common stock warrants, warrants to purchase an aggregate of 7,299,270 shares will expire on April 5, 2025, and warrants to purchase an aggregate of 7,299,270 shares will expire on October 5, 2028. The accompanying common stock warrants have an exercise price of $1.37 per share and became exercisable immediately upon issuance. On October 18, 2021, the Company issued and sold to New Enterprise Associates 16, L.P., an existing stockholder of the Company (“NEA”) and related party, in a private placement, 1,851,852 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 3,703,704 shares of the Company’s common stock. Each share of the Company’s common stock and accompanying common stock warrants were sold together at a combined price of $1.62 for gross proceeds of approximately $3.0 million. Of the accompanying common stock warrants, warrants to purchase an aggregate of 1,851,852 shares of the Company’s common stock will expire on April 18, 2025, and warrants to purchase an aggregate of 1,851,852 shares of the Company’s common stock will expire on October 18, 2028. The accompanying common stock warrants have an exercise price of $1.37 per share and became exercisable immediately upon issuance.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim Condensed Consolidated Financial Statements for the three and nine months ended September 30, 2021 and 2020 included herein, have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) for interim financial information and the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim information. Certain prior year balances have been reclassified to conform to the current year presentation. Such reclassifications did not affect loss from operations or net loss. Certain information and footnote disclosures typically prepared in accordance with GAAP have been condensed or omitted pursuant to SEC rules and regulations. The accompanying unaudited Condensed Consolidated Financial Statements and notes should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (the “Annual Report on Form 10-K”). The accompanying Condensed Consolidated Financial Statements include the accounts of Trevi Therapeutics, Inc. and its wholly-owned subsidiary Trevi Therapeutics Limited. Intercompany balances and transactions have been eliminated. All amounts presented are in thousands of dollars, except share and per share amounts, unless noted otherwise. The Company has evaluated events occurring subsequent to September 30, 2021 for potential recognition or disclosure in the Condensed Consolidated Financial Statements. Refer to Note 12 for disclosure related to events occurring subsequent to September 30, 2021.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of the expenses during the reporting periods. Significant estimates and assumptions reflected in these Condensed Consolidated Financial Statements include, but are not limited to, the recognition of research and development (“R&D”) expenses, the valuation of stock-based awards and the valuation allowance of deferred tax assets resulting from net operating losses. In addition, management’s assessment of the Company’s ability to continue as a going concern involves the estimation of the amount and timing of future cash inflows and outflows. On an ongoing basis, management evaluates its estimates in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. The inputs into the Company’s estimates also considered the economic implications of the COVID-19 pandemic on the Company’s estimates.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying interim Condensed Consolidated Balance Sheet as of September 30, 2021 and the Condensed Consolidated Statements of Operations, the Condensed Consolidated Statements of Stockholders’ Equity and the Condensed Consolidated Statements of Cash Flows for the three and nine months ended September 30, 2021 and 2020 are unaudited. The unaudited interim Condensed Consolidated Financial Statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the Company’s opinion, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statements of its financial position as of September 30, 2021 and the results of its operations and its cash flows for the three and nine months ended September 30, 2021 and 2020. The results for the three and nine months ended September 30, 2021 and 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2021 or any other interim period or any future year or period.
Cash Equivalents	Cash Equivalents The Company classifies short-term, highly liquid investments with an original term of three months or less at the date of purchase as cash equivalents.
Fair Value Measurements	Fair Value Measurements The Company’s financial instruments have consisted of cash and cash equivalents, other current assets, accounts payable, accrued expenses, term loans and term loan derivative liability (Note 6). Fair specific point in time, based on relevant market information. The carrying amounts of cash and cash equivalents, other current assets, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of the short - term nature of those instruments. The carrying amount of the term loan approximates its fair value due to its floating market-based interest rate. The term loan derivative liability is recorded at fair value , which is estimated utilizing a probability-weighted cash flow approach (Note 6). Current accounting guidance defines fair value, establishes a framework for measuring fair value in accordance with Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures Level 1—Observable inputs—quoted prices in active markets for identical assets and liabilities. Level 2—Observable inputs other than the quoted prices in active markets for identical assets and liabilities—such as quoted prices for similar instruments, quoted prices for identical or similar instruments in inactive markets or other inputs that are observable or can be corroborated by observable market data. Level 3—Unobservable inputs—includes amounts derived from valuation models where one or more significant inputs are unobservable and require the company to develop relevant assumptions. The following table summarizes the financial assets and financial liabilities measured at fair value on a recurring basis and the basis for that measurement, by level within the fair value hierarchy (Note 6): Level 1 Level 2 Level 3 September 30, 2021 Financial assets carried at fair value: Money market funds (1) $ 28,325 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 167 December 31, 2020 Financial assets carried at fair value: Money market funds (1) $ 44,095 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 196 (1) The following table represents a roll-forward of the fair value of Level 3 instruments (significant unobservable inputs): September 30, 2021 December 31, 2020 Financial liabilities Balance at beginning of period $ 196 $ 187 Change in fair value of term loan derivative liability (29 ) 9 Balance at end of period $ 167 $ 196
Property, Equipment and Leasehold Improvements	Property, Equipment and Leasehold Improvements Property, equipment and leasehold improvements (consisting of furniture, computer and office equipment and leasehold improvements) are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets (three years for computer equipment, five years for furniture and office equipment and the shorter of the term of the lease or useful life for leasehold improvements).
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets ASC 360, Property, Plant and Equipment,
Foreign Currency Transactions	Foreign Currency Transactions The Company, at times, contracts with vendors and consultants outside of the U.S., resulting in liabilities denominated in foreign currency. The transactions are recorded in U.S. dollars on the transaction dates and any currency fluctuation through the payment date is recorded as currency gains or losses in the Condensed Consolidated Statements of Operations.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded in stockholders’ equity as a reduction of additional paid-in capital generated as a result of the financing. Should the planned equity financing no longer be considered probable of being consummated, the deferred offering costs are expensed immediately as a charge to operating expenses.
Research and Development Expenses	Research and Development Expenses All of the Company’s research and development expenses consist of expenses incurred in connection with the development of Haduvio. These expenses include certain payroll and personnel expenses, including stock-based compensation, consulting costs, contract manufacturing costs and fees paid to clinical research organizations (“CROs”) to conduct certain research and development activities on the Company’s behalf. The Company does not allocate its costs by each indication for which it is developing Haduvio, as a significant amount of the Company’s development activities broadly support all indications. In addition, several of the Company’s departments support the Company’s Haduvio drug candidate development program and the Company does not identify internal costs for each potential indication. The Company expenses both internal and external research and development expenses as they are incurred.
Accrued Research and Development Expenses	Accrued Research and Development Expenses The Company has entered into agreements with CROs, contract manufacturing organizations (“CMOs”) and other companies that provide services in connection with the Company’s research and development activities. The Company’s research and development accruals are estimated based on the level of services performed, progress of the studies, including the phase or completion of events and contracted costs. The estimated costs of research and development provided, but not yet invoiced, are included in accrued expenses on the Condensed Consolidated Balance Sheets. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to CROs, CMOs and other companies under these arrangements in advance of the performance of the related services are recorded as prepaid expenses or as other non-current assets, as applicable, and are recognized as expenses as the goods are delivered or the related services are performed.
Patent Costs	Patent Costs All patent-related costs in connection with filing and prosecuting patent applications are expensed to general and administrative expense as incurred, as recoverability of such expenditures is uncertain.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees and non-employees for consultancy services in accordance with ASC 718, Stock Compensation The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. For performance-based vesting, the fair value is also recognized on a straight-line basis over the requisite service period based on whether the performance conditions are probable. The Company reassesses the probability of achieving the performance conditions at each reporting date. Forfeitures are accounted for as they occur. Estimating the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require analysis and judgment to develop. Expected Term—The expected term assumption represents the weighted average period that the stock-based awards are expected to be outstanding. The Company has elected to use the “simplified method” for estimating the expected term of the options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. Expected Volatility—For all stock options granted to date, the volatility data was estimated based on a study of publicly traded industry peer companies. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. Expected Dividend—The Black-Scholes valuation model calls for a single expected dividend yield as an input. The Company currently has no history or expectation of paying cash dividends on its common stock. Risk-Free Interest Rate—The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. Prior to the Company’s IPO in May 2019, the estimated fair value of the common stock underlying the Company’s stock options was determined at each grant date by the Company’s board of directors, with input from management. All options to purchase shares of common stock were intended to be exercisable at a price per share not less than the per share fair value of the Company’s common stock underlying those options on the date of grant. In the absence of a public trading market for the Company’s common stock prior to the Company’s IPO in May 2019, on each grant date, the Company developed an estimate of the fair value of its common stock based on the information known to the Company on the date of grant, upon a review of any recent events and their potential impact on the estimated fair value per share of the common stock and in part on input from an independent third-party valuation. As is provided for in Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”), the Company generally relied on valuations for up to twelve months unless the Company had experienced a material event that would have affected the estimated fair value of its common stock. The valuations of the Company’s common stock performed prior to the Company’s IPO in May 2019, were determined in accordance with the guidelines outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “Practice Aid”). The methodology to determine the fair value of common stock included estimating the fair value of the enterprise using a market approach, which estimates the fair value of the Company by including an estimation of the value of the business based on the guideline public companies under a number of different scenarios. The assumptions used to determine the estimated fair value of the Company’s common stock were based on numerous objective and subjective factors, combined with management judgment, including external market conditions affecting the pharmaceutical and biotechnology industry and trends within the industry; the Company’s stage of development; the rights, preferences and privileges of the Company’s convertible preferred stock relative to those of the Company’s common stock; the prices at which the Company sold shares of convertible preferred stock; the Company’s financial condition and operating results, including the Company’s levels of available capital resources; the progress of the Company’s research and development efforts; the stage of development and business strategy; the equity market conditions affecting comparable public companies; the general U.S. market conditions and the lack of marketability of the Company’s common stock. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In accordance with the Practice Aid, the Company considered the following methods: • Option Pricing Method (“OPM”)—The OPM treats common stock and convertible preferred stock as call options on the total equity value of a company, with exercise prices based on the value thresholds at which the allocation among the various holders of a company’s securities changes. Under this method, the common stock has value only if the funds available for distribution to stockholders exceed the value of the liquidation preferences at the time of a liquidity event, such as a strategic sale or merger. The common stock is modeled as a call option on the underlying equity value at a predetermined exercise price. In the model, the exercise price is based on a comparison with the total equity value rather than, as in the case of a regular call option, a comparison with a per share stock price. Thus, common stock is considered to be a call option with a claim on the enterprise at an exercise price equal to the remaining value immediately after the convertible preferred stock liquidation preference is paid. The OPM uses the Black-Scholes option-pricing model to price the call options. This model defines the securities’ fair values as functions of the current fair value of a company and uses assumptions, such as the anticipated timing of a potential liquidity event and the estimated volatility of the equity securities. • Probability Weighted Expected Return Method (“PWERM”)—Under the PWERM methodology, the fair value of common stock is estimated based upon an analysis of future values for the company, assuming various outcomes. The common stock value is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes available as well as the rights of each class of stock. The future value of the common stock under each outcome is discounted back to the valuation date at an appropriate risk-adjusted discount rate and probability weighted to arrive at an indication of value for the common stock. • Hybrid Method—The hybrid method is a PWERM where the equity value in one of the scenarios is calculated using an OPM. In the hybrid method used by the Company, it considered an IPO as the other potential future liquidity event. The equity value for the IPO scenario was determined using the guideline public company (“GPC”), method under the market approach. The relative probability of the IPO scenario was determined based on an analysis of market conditions at the time and expectations as to the timing and likely prospects of the IPO at each valuation date. In application of the GPC method, the Company considered publicly traded companies in the biopharmaceutical industry that had a similar profile to the Company’s as well as recently completed IPOs as indicators of estimated future value in an IPO. The Company then discounted that future value back to the valuation date at an appropriate discount rate. In determining the estimated fair value of the Company’s common stock prior to Company’s IPO in May 2019, the board of directors considered the fact that the Company’s stockholders could not freely trade the Company’s common stock in the public markets. Accordingly, the Company’s board of directors applied discounts to reflect the lack of marketability of common stock based on the weighted-average expected time to liquidity. The estimated fair value of the Company’s common stock at each grant date reflected a non-marketability discount partially based on the anticipated likelihood and timing of a future liquidity event. Subsequent to the completion of the Company’s IPO in May 2019, the fair value of the Company’s common stock has been determined based on the closing price of the Company’s common stock as reported on the date of grant on the primary stock exchange on which the Company’s common stock is traded.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The Company applies the provisions of ASC 740, Income Taxes
Leases	Leases Under ASC 842, Leases Operating lease right-of-use assets and operating lease liabilities are determined and recognized on the commencement date of the lease based on the present value of lease payments over the term of the lease. As the Company’s leases do not provide an implicit rate within the lease, the Company uses its incremental borrowing rate, which is updated periodically, based on information available at the commencement date of the lease to determine the present value of the lease payments.
Basic and Diluted Net Income (Loss) per Common Share	Basic and Diluted Net Loss per Common Share Basic and diluted net loss per common share outstanding is determined by dividing net loss by the weighted average common shares outstanding during the period. For all periods presented, shares issuable upon exercise of stock options have been excluded from the calculation because their effects would be anti-dilutive. Therefore, the weighted average common shares used to calculate both basic and diluted net loss per share are the same for each of the periods presented.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements On January 1, 2021, the Company adopted ASU No. 2019-12- Income Taxes (Topic 740) Recently Issued Accounting Pronouncements There have been no new accounting pronouncements during the nine months ended September 30, 2021, which could be expected to materially impact the Company’s Condensed Consolidated Financial Statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes the financial assets and financial liabilities measured at fair value on a recurring basis and the basis for that measurement, by level within the fair value hierarchy (Note 6): Level 1 Level 2 Level 3 September 30, 2021 Financial assets carried at fair value: Money market funds (1) $ 28,325 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 167 December 31, 2020 Financial assets carried at fair value: Money market funds (1) $ 44,095 $ — $ — Financial liabilities carried at fair value: Term loan derivative liability $ — $ — $ 196 (1)
Schedule of Fair Value, Financial Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	The following table represents a roll-forward of the fair value of Level 3 instruments (significant unobservable inputs): September 30, 2021 December 31, 2020 Financial liabilities Balance at beginning of period $ 196 $ 187 Change in fair value of term loan derivative liability (29 ) 9 Balance at end of period $ 167 $ 196

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Prepaid Expense And Other Assets Current [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: September 30, 2021 December 31, 2020 Prepaid corporate insurance $ 1,007 $ 562 Prepaid other and other current assets 234 373 Prepaid R&D costs 148 333 Total prepaid expenses and other current assets $ 1,389 $ 1,268

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Schedule of Balance Sheet Information Related to Operating Leases	The following table summarizes the Company’s operating lease as presented on its Condensed Consolidated Balance Sheets: September 30, 2021 December 31, 2020 Assets: Operating lease right-of-use asset $ 156 $ 227 Liabilities: Operating lease liabilities, current portion 116 113 Operating lease liabilities, long term portion 58 144 Total operating lease liabilities $ 174 $ 257
Future Minimum Lease Payments for Non-cancellable Operating Leases	Future minimum lease payments from September 30, 2021 until the expiration of the operating leases are as follows: 2021 $ 34 2022 131 2023 24 Total lease payments 189 Less: imputed discount rate (15 ) Carrying value of operating lease liabilities $ 174

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: September 30, 2021 December 31, 2020 Accrued R&D projects $ 1,660 $ 1,754 Accrued compensation and benefits 960 954 Accrued consulting and professional fees 624 560 Accrued other 70 158 Total accrued expenses $ 3,314 $ 3,426

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Outstanding Borrowings under SVB Term Loan	As of September 30, 2021, the Company had outstanding borrowings of $14.0 million under the SVB Term Loan and the term loan payable balance as presented on the Company’s Condensed Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020 was comprised as shown below. September 30, 2021 December 31, 2020 Principal outstanding under term loan $ 14,000 $ 14,000 Term loan discount-interest (102 ) (158 ) Term loan discount-unamortized deferred charges (93 ) (48 ) Term loan discount-financing costs, net of accretion (15 ) (23 ) Term loan-final payment fee 538 183 14,328 13,954 Less current portion 4,083 - Term loan payable, non-current $ 10,245 $ 13,954
Schedule of Components of Interest Expense of Term Loan	Interest expense on the SVB Term Loan, which is comprised of interest payments, accretion and amortization of term loan discounts and the accrual of the final payment fee, is shown below for the three and nine months ended September 30, 2021 and 2020, respectively. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Interest payments $ 152 $ 80 $ 451 $ 80 Accretion and amortization of term loan discounts 33 4 87 4 Accrual of the final payment fee 118 64 355 64 $ 303 $ 148 $ 893 $ 148

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders Equity Note [Abstract]
Schedule of Common Stock Reserved for Future Issuance	As of September 30, 2021 and December 31, 2020, the Company had reserved September 30, 2021 December 31, 2020 Shares of common stock reserved for future issuance under the 2012 Stock Incentive Plan 761,553 921,824 Shares of common stock reserved for future issuance under the 2019 Stock Incentive Plan 3,299,064 2,396,922 Shares of common stock reserved for future issuance under the 2019 Employee Stock Purchase Plan 503,789 327,454 4,564,406 3,646,200
Schedule of Share-based Compensation, Stock Options, Activity	A summary of the Company’s combined stock option activity for the 2019 Plan and the 2012 Plan for the nine months ended September 30, 2021 is as follows: Number of Option Shares Weighted Average Exercise Price Outstanding as of December 31, 2020 2,171,477 $ 5.62 Granted 1,474,875 $ 2.94 Forfeited (420,241 ) $ 4.39 Expired (176,931 ) $ 6.30 Exercised — $ — Outstanding as of September 30, 2021 3,049,180 $ 4.45 Options exercisable as of September 30, 2021 1,304,796 $ 5.02 Options unvested as of September 30, 2021 1,744,384 $ 4.03
Schedule of Stock-based Compensation Expenses Recognized	The following table summarizes the classifications of stock-based compensation expenses for the 2012 Plan, the 2019 Plan and the 2019 ESPP recognized in the Condensed Consolidated Statements of Operations: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expense $ 169 $ 82 $ 593 $ 259 General and administrative expense 371 506 1,410 1,648 $ 540 $ 588 $ 2,003 $ 1,907

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net loss $ (7,255 ) $ (7,378 ) $ (25,420 ) $ (23,235 ) Weighted average common shares used in net loss per share attributable to common stockholders, basic and diluted 21,607,979 18,134,886 20,390,852 17,935,865 Basic and diluted net loss per common share outstanding $ (0.34 ) $ (0.41 ) $ (1.25 ) $ (1.30 )

Nature of the Business - Additi

Nature of the Business - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net income loss	$ (7,255)	$ (7,378)	$ (25,420)	$ (23,235)	$ (32,800)
Retained earnings accumulated deficit	(172,397)		(172,397)		(146,977)
Cash and cash equivalents, at carrying value	$ 29,318		$ 29,318		$ 45,001

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial liabilities carried at fair value:
Term loan derivative liability		$ 196
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Money Market Funds [Member]
Financial assets carried at fair value:
Money market funds	$ 28,325	44,095
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Term Loan Derivative Liability [Member]
Financial liabilities carried at fair value:
Term loan derivative liability	$ 167	$ 196

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Fair Value, Financial Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 196	$ 187
Balance at end of period	167	196
Term Loan Derivative Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of term loan derivative liability	$ (29)	$ 9

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2021USD ($)
Summary Of Significant Accounting Policies [Line Items]
Dividends, common stock, cash	$ 0
Accounting Standards Update No. 2019-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change In Accounting Principle Accounting Standards Update Adopted	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2021
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect	true
Computer Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Equipment and leasehold improvements, useful life	3 years
Furniture and Office Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, Equipment and leasehold improvements, useful life	5 years

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Prepaid corporate insurance	$ 1,007	$ 562
Prepaid other and other current assets	234	373
Prepaid R&D costs	148	333
Total prepaid expenses and other current assets	$ 1,389	$ 1,268

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	Mar. 01, 2018USD ($)ft²	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)Lease	Sep. 30, 2020USD ($)
Operating lease, weighted average discount rate, percent		13.00%		13.00%
Number of new leases | Lease				0
Remaining terms		1 year 6 months		1 year 6 months
Operating Lease, Payments		$ 35	$ 23	$ 104	$ 103
Building [Member]
Leased spaced area | ft²	5,600
Operating lease term	60 months
Building [Member] | Minimum [Member]
Operating lease rent expense	$ 10
Building [Member] | Maximum [Member]
Operating lease rent expense	$ 11
Office Equipment [Member]
Operating lease rent expense		$ 29	$ 31	$ 90	$ 93

Leases - Schedule of Balance Sh

Leases - Schedule of Balance Sheet Operating Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets:
Operating lease right-of-use asset	$ 156	$ 227
Liabilities:
Operating lease liability - current portion	116	113
Operating lease liability - long term portion	58	144
Total operating lease liabilities	$ 174	$ 257

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Leases [Abstract]
2021	$ 34
2022	131
2023	24
Total lease payments	189
Less: imputed discount rate	(15)
Carrying value of operating lease liabilities	$ 174	$ 257

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued R&D projects	$ 1,660	$ 1,754
Accrued compensation and benefits	960	954
Accrued consulting and professional fees	624	560
Accrued other	70	158
Total accrued expenses	$ 3,314	$ 3,426

Debt - Additional Information (

Debt - Additional Information (Detail) $ in Thousands	Jul. 06, 2021USD ($)	Aug. 13, 2020USD ($)Installment	Oct. 31, 2021PrivatePlacement	Sep. 30, 2021USD ($)	Oct. 31, 2021USD ($)	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Aug. 31, 2020USD ($)
Subsequent Event [Member] | Private Placement [Member]
Number of private placements | PrivatePlacement			2
SVB Term Loan [Member]
Debt instrument, principal amount		$ 14,000		$ 14,000		$ 14,000	$ 14,000
Interest-only payment period		24 months
Loan payment, number of consecutive equal monthly installments of principal including accrued interest | Installment		24
Debt instrument, maturity date						Feb. 1, 2024
Debt instrument, final payment fee amount		$ 1,200		1,200		$ 1,200
Debt default additional interest charge		5.00%
Debt finance costs	$ 68							$ 57
Amortization of deferred financing charges				11		22
Unamortized deferred charges				93		93	48
Financing costs paid								$ 27
Accretion loan discounts				3		8
Loan discounts-financing costs				15		15	23
Debt instrument, accrued final payment fee				538		$ 538	183
Contingent interest rate increase						2.00%
Fair value of liabilities				29		$ 29
Amortization of term loan				19		56
Term loan discount interest				102		102	158
SVB Term Loan [Member] | Term Loan Derivative Liability [Member]
Term loan derivative liability		$ 187		$ 167		$ 167	$ 196
SVB Term Loan [Member] | Term Loan Derivative Liability [Member] | Contingent Interest Rate Increase [Member]
Derivative liability, measurement input				0.0200		0.0200
SVB Term Loan [Member] | Term Loan Derivative Liability [Member] | Discount Rate [Member]
Derivative liability, measurement input				0.120		0.120
SVB Term Loan [Member] | Minimum [Member]
Interest rate, floating		4.25%
Long term debt percentage bearing adjusted floating interest rate		6.25%
SVB Term Loan [Member] | First Amendment
Debt instruments percentage of required to deposit unrestricted and unencumbered cash collateral	100.00%
Equity raise requirements, description						if the Company fails to receive positive data in its Phase 2b/3 PRISM trial or to raise by June 30, 2022 sufficient net proceeds from the sale of equity securities to finance its planned second phase 3 clinical trial of Haduvio for prurigo nodularis and its ongoing operations (each a “Milestone Condition”), the Company will be required to deposit unrestricted and unencumbered cash equal to 100% of the principal amount of the SVB Term Loan then outstanding in a cash collateral account with SVB, which can be used by SVB to prepay the SVB Term Loan at any time.
Debt instruments amount of required to maintain unrestricted and unencumbered cash	$ 20,000
SVB Term Loan [Member] | Prepayment Prior to First Anniversary of Effective Date [Member]
Prepayment premium percentage on principal amount		3.00%
SVB Term Loan [Member] | Prepayment After First Anniversary of Effective Date and Prior To Second Anniversary of Effective Date [Member]
Prepayment premium percentage on principal amount		2.00%
SVB Term Loan [Member] | Prepayment After Second Anniversary of the Effective Date and Prior to February 1, 2024 [Member]
Prepayment premium percentage on principal amount		1.00%
SVB Term Loan [Member] | Prime Rate [Member]
Variable interest rate		1.00%
SVB Term Loan [Member] | Adjusted Prime Rate [Member]
Variable interest rate		3.00%
SVB Term Loan [Member] | Subsequent Event [Member] | First Amendment | Minimum [Member]
Proceeds from the sale of equity securities					$ 15,000

Debt - Schedule of Outstanding

Debt - Schedule of Outstanding Borrowings under SVB Term Loan (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Aug. 13, 2020
Term loan - current portion	$ 4,083
Term loan payable, non-current	10,245	$ 13,954
SVB Term Loan [Member]
Principal outstanding under term loan	14,000	14,000	$ 14,000
Term loan discount-interest	(102)	(158)
Term loan discount-unamortized deferred charges	(93)	(48)
Term loan discount-financing costs, net of accretion	(15)	(23)
Debt instrument, accrued final payment fee	538	183
Loans Payable, Noncurrent	14,328	13,954
Term loan - current portion	4,083
Term loan payable, non-current	$ 10,245	$ 13,954

Debt - Schedule of Components o

Debt - Schedule of Components of Interest Expense of Term Loan (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Interest expense	$ 303	$ 148	$ 893	$ 148
SVB Term Loan [Member]
Debt Instrument [Line Items]
Interest payments	152	80	451	80
Accretion and amortization of term loan discounts	33	4	87	4
Accrual of the final payment fee	118	64	355	64
Interest expense	$ 303	$ 148	$ 893	$ 148

Stockholders' Equity - Shares R

Stockholders' Equity - Shares Reserved For Future Issuances (Detail) - shares	Sep. 30, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	4,564,406	3,646,200
2012 Stock Option And Grant Plan [Member] | 2012 Stock Incentive Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	761,553	921,824
2019 Stock Option And Grant Plan [Member] | 2019 Stock Incentive Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	3,299,064	2,396,922
2019 Stock Option And Grant Plan [Member] | 2019 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	503,789	327,454

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail)	Jun. 18, 2021shares	Oct. 31, 2021PrivatePlacement	Jun. 30, 2020USD ($)	Sep. 30, 2021USD ($)shares	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)shares
Stockholders Equity [Line Items]
Estimated commissions and allocated fees					$ 420,000	$ 343,000
ATM Sales Agreement [Member]
Stockholders Equity [Line Items]
Aggregate offering price of common stock which may issue and sell under agreement			$ 12,000,000
Sale of stock during the period | shares				162,026	2,895,518		3,583,394
Proceeds from issuance of common stock				$ 300,000	$ 7,700,000		$ 10,900,000
Estimated commissions and allocated fees					$ 600,000		$ 800,000
ATM Sales Agreement [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Estimated commissions and allocated fees				$ 100,000
Common Stock Purchase Agreement [Member] | Lincoln Park Capital Fund, LLC [Member]
Stockholders Equity [Line Items]
Shares agreed to be issued over period under equity line financing	24 months
Issuance of common stock to Lincoln Park Capital Fund, shares | shares	170,088
Common Stock Purchase Agreement [Member] | Maximum [Member] | Lincoln Park Capital Fund, LLC [Member]
Stockholders Equity [Line Items]
Shares agreed to be issued under equity line financing | shares	15
Subsequent Event [Member] | Private Placement [Member]
Stockholders Equity [Line Items]
Number of private placements | PrivatePlacement		2

Stockholders' Equity (Stock-Bas

Stockholders' Equity (Stock-Based Awards) - Additional Information (Detail) - shares	Jan. 01, 2021	Jan. 01, 2020	Apr. 30, 2019	Sep. 30, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance				4,564,406	3,646,200
Share based compensation options to purchase no of common stock				3,049,180	2,171,477
Share based compensation options grants in the period				1,474,875
2019 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, award description				The total number of shares of common stock that may be issued under the 2019 Plan and the 2012 Plan was 4,060,617 as of September 30, 2021, of which 1,011,437 shares remained available for grant under the 2019 Plan. Awards may be made under the 2019 Plan for up to such number of shares of the Company’s common stock as is equal to the sum of i) 1,578,947 shares; plus ii) the number of shares (up to 1,157,894 shares) equal to the number of shares of the Company’s common stock subject to outstanding awards under the 2012 Stock Incentive Plan (the “2012 Plan”)  that expire, terminate or are otherwise cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right; plus iii) an annual increase to be added on the first day of each fiscal year, beginning with 2020 and continuing through 2029, equal to the lesser of (a) 2,105,623 shares of common stock, (b) 4% of the number of outstanding shares of the Company’s common stock on such date and (c) an amount determined by the Company’s board of directors.
Number of shares available for grant				1,011,437
Common stock, capital shares reserved for future issuance	741,871	713,383		1,578,947
Share based compensation grant period				10 years
Share based compensation vesting description				Options granted under the 2019 Plan and the 2012 Plan have a maximum term of ten years. Options granted to employees, officers and non-employees generally vest over four years based on varying vesting schedules that primarily include: 25% vesting on the first anniversary date of grant and the balance ratably over the next 36 months or vesting in equal monthly or quarterly installments over four years.
Share based compensation options to purchase no of common stock				2,287,627	1,249,653
2019 Stock Incentive Plan [Member] | Employees, Officers and Non-employee Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				4 years
2019 Stock Incentive Plan [Member] | Employees, Officers and Non-employee Consultants [Member] | Vesting First Anniversary Date of Grant [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting Percentage				25.00%
2019 Stock Incentive Plan [Member] | Director [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				1 year
2019 Stock Incentive Plan [Member] | Director [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				2 years
2019 Stock Incentive Plan [Member] | Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in additional number of shares to be issued		2,105,623
Percentage of number of common stock, shares outstanding	4.00%	4.00%
2019 Plan and 2012 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total number of common shares authorized under the plan				4,060,617
2012 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation grant period				10 years
Share based compensation vesting description				Options granted under the 2019 Plan and the 2012 Plan have a maximum term of ten years. Options granted to employees, officers and non-employees generally vest over four years based on varying vesting schedules that primarily include: 25% vesting on the first anniversary date of grant and the balance ratably over the next 36 months or vesting in equal monthly or quarterly installments over four years.
Share based compensation options to purchase no of common stock				761,553	921,824
2012 Stock Incentive Plan [Member] | Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation options grants in the period				0
2012 Stock Incentive Plan [Member] | Other Equity-Based Award [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation options grants in the period				0
2012 Stock Incentive Plan [Member] | Employees, Officers and Non-employee Consultants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				4 years
2012 Stock Incentive Plan [Member] | Employees, Officers and Non-employee Consultants [Member] | Vesting First Anniversary Date of Grant [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting Percentage				25.00%
2012 Stock Incentive Plan [Member] | Director [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				1 year
2012 Stock Incentive Plan [Member] | Director [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation vesting period				2 years
2012 Stock Incentive Plan [Member] | Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation options to purchase number of shares outstanding				1,157,894
2019 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, award description				The total number of shares of common stock that may be issued under the 2019 ESPP Plan was 518,918 as of September 30, 2021, of which 503,789 shares remain available for issuance. The number of shares of the Company’s common stock that have been approved to be issued under the 2019 ESPP is equal to the sum of i) 155,106 shares plus ii) an annual increase to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2020 and continuing for each fiscal year until and including, the fiscal year ending December 31, 2029, equal to the least of (a) 526,315 shares of common stock, (b) 1% of the number of outstanding shares of the Company’s common stock on such date and (c) an amount determined by the Company’s board of directors. Effective January 1, 2021 and January 1, 2020, respectively, the aggregate number of shares of the Company’s common stock that may be issued under the 2019 ESPP increased, pursuant to the terms of the 2019 ESPP, by an additional 185,467 shares and 178,345 shares, equal to 1% of the Company’s then-outstanding common stock
Total number of common shares authorized under the plan				518,918
Number of shares available for grant				503,789
Common stock, capital shares reserved for future issuance			155,106
2019 Employee Stock Purchase Plan [Member] | Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in additional number of shares to be issued	185,467	178,345	526,315
Percentage of number of common stock, shares outstanding	1.00%	1.00%	1.00%

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options, Activity (Detail)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of Option Shares
Outstanding, Beginning | shares	2,171,477
Granted | shares	1,474,875
Forfeited | shares	(420,241)
Expired | shares	(176,931)
Outstanding, Ending | shares	3,049,180
Options exercisable | shares	1,304,796
Options unvested | shares	1,744,384
Weighted Average Exercise Price
Outstanding, Beginning | $ / shares	$ 5.62
Granted | $ / shares	2.94
Forfeited | $ / shares	4.39
Expired | $ / shares	6.30
Outstanding, Ending | $ / shares	4.45
Options exercisable | $ / shares	5.02
Options unvested | $ / shares	$ 4.03

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock-based compensation	$ 540	$ 588	$ 2,003	$ 1,907
Research and Development Expense [Member]
Stock-based compensation	169	82	593	259
General and Administrative Expense [Member]
Stock-based compensation	$ 371	$ 506	$ 1,410	$ 1,648

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Earnings Per Share [Abstract]
Net loss	$ (7,255)	$ (7,378)	$ (25,420)	$ (23,235)	$ (32,800)
Weighted average common shares used in net loss per share attributable to common stockholders, basic and diluted	21,607,979	18,134,886	20,390,852	17,935,865
Basic and diluted net loss per common share outstanding	$ (0.34)	$ (0.41)	$ (1.25)	$ (1.30)

Collaborative and Licensing A_2

Collaborative and Licensing Agreements - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Nov. 30, 2018	Sep. 30, 2021
Endo Pharmaceuticals Inc [Member]
Royalty terms		first commercial sale of the product in that country and extends until the later of the expiration, unenforceability or invalidation of the last valid claim of any licensed patent or application covering the licensed product in the country or the expiration of 10 years after the first commercial sale of the licensed product in the country, which period is referred to as the royalty term. Upon the expiration of the royalty term for a product in a country
Endo Pharmaceuticals Inc [Member] | Completion Of Stage One [Member]
Milestone payments to be paid		$ 0.3
Endo Pharmaceuticals Inc [Member] | Completion Of Stage Two [Member]
Milestone payments to be paid		0.8
Rutgers [Member]
Milestone payments to be paid		$ 0.3
Royalty terms		first commercial sale of the licensed product in that country following receipt of marketing approval and extends until the later of the date of expiration, unenforceability or invalidation of the last valid claim of any licensed patent or patent application covering the licensed product in the country and 10 years after the first commercial sale of the first licensed product sold anywhere in the world, which period is referred to as the royalty term. Upon the expiration of the royalty term for a licensed product in a country, the license granted to the Company under the agreement shall become perpetual, fully paid-up, irrevocable and royalty-free in such country.
MentiNova, LLC [Member]
Upfront license fee	$ 0.1
MentiNova, LLC [Member] | Completion Of Stage One [Member]
Milestone payments to be paid		$ 1.2

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Oct. 18, 2021	Oct. 05, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Common Stock [Member]
Subsequent Event [Line Items]
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)			162,026	466,758	2,895,518	466,758
Subsequent Event [Member] | Private Placement [Member] | Investor [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock		4,746,402
Subsequent Event [Member] | Private Placement [Member] | New Enterprise Associates 16, L.P [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock	3,703,704
Subsequent Event [Member] | Private Placement [Member] | Common Stock [Member] | Investor [Member]
Subsequent Event [Line Items]
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)		2,373,201
Subsequent Event [Member] | Private Placement [Member] | Common Stock [Member] | New Enterprise Associates 16, L.P [Member]
Subsequent Event [Line Items]
Issuance of common stock under the at-the-market sales agreement, net of commissions and allocated fees (in shares)	1,851,852
Subsequent Event [Member] | Private Placement [Member] | Pre-funded Warrants [Member] | Investor [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock		9,852,138
Exercise price per share of warrants		$ 0.001
Subsequent Event [Member] | Private Placement [Member] | Pre-funded Warrants [Member] | Investor [Member] | Maximum [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock		4,926,069
Subsequent Event [Member] | Private Placement [Member] | Common Stock and Accompanying Common Stock Warrants [Member] | Investor [Member]
Subsequent Event [Line Items]
Combined price of each shares		$ 1.62
Subsequent Event [Member] | Private Placement [Member] | Common Stock and Accompanying Common Stock Warrants [Member] | New Enterprise Associates 16, L.P [Member]
Subsequent Event [Line Items]
Combined price of each shares	$ 1.62
Gross proceeds from private placement	$ 3
Subsequent Event [Member] | Private Placement [Member] | Pre-funded Warrant and Accompanying Common Stock Warrants [Member] | Investor [Member]
Subsequent Event [Line Items]
Combined price of each shares		$ 1.619
Gross proceeds from private placement		$ 11.8
Subsequent Event [Member] | Private Placement [Member] | Common Stock Warrants | Investor [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock		7,299,270
Exercise price per share of warrants		$ 1.37
Warrants expiration date		Apr. 5, 2025
Subsequent Event [Member] | Private Placement [Member] | Common Stock Warrants | New Enterprise Associates 16, L.P [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock	1,851,852
Exercise price per share of warrants	$ 1.37
Warrants expiration date	Apr. 18, 2025
Subsequent Event [Member] | Private Placement [Member] | Warrants [Member] | Investor [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock		7,299,270
Warrants expiration date		Oct. 5, 2028
Subsequent Event [Member] | Private Placement [Member] | Warrants [Member] | New Enterprise Associates 16, L.P [Member]
Subsequent Event [Line Items]
Warrants to purchase aggregate shares of common stock	1,851,852
Warrants expiration date	Oct. 18, 2028