Allena Pharmaceuticals (ALNAQ) 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 05, 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
Trading Symbol	ALNA
Entity Registrant Name	ALLENA PHARMACEUTICALS, INC.
Entity Central Index Key	0001624658
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		82,571,078
Entity File Number	001-38268
Entity Tax Identification Number	45-2729920
Entity Address, Address Line One	One Newton Executive Park
Entity Address, Address Line Two	Suite 202
Entity Address, City or Town	Newton
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02462
City Area Code	617
Local Phone Number	467-4577
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 40,421	$ 35,042
Prepaid expenses and other current assets	1,533	2,207
Total current assets	41,954	37,249
Property and equipment, net	1,270	881
Operating lease assets	518	678
Other assets	128	123
Total assets	43,870	38,931
Current liabilities:
Accounts payable	3,027	2,410
Accrued expenses and other current liabilities	4,346	3,421
Operating lease liabilities, net of discount	300	291
Total current liabilities	7,673	6,122
Loan payable, net of current portion and discount	9,893	9,853
Operating lease liabilities, net of current portion	274	387
Total liabilities	17,840	16,362
Commitments and contingencies (Note 6)
Stockholders’ equity:
Undesignated preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 200,000,000 and 125,000,000 shares authorized at September 30, 2021 and December 31, 2020, respectively; 80,140,728 and 50,821,361 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	80	51
Additional paid-in capital	262,039	220,307
Accumulated deficit	(236,089)	(197,789)
Total stockholders’ equity	26,030	22,569
Total liabilities and stockholders’ equity	$ 43,870	$ 38,931

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (unaudited) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Undesignated preferred stock, par value	$ 0.001	$ 0.001
Undesignated preferred stock, shares authorized	5,000,000	5,000,000
Undesignated preferred stock, shares issued	0	0
Undesignated preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	125,000,000
Common stock, shares issued	80,140,728	50,821,361
Common stock, shares outstanding	80,140,728	50,821,361

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - 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	$ 9,024	$ 4,952	$ 26,966	$ 13,406
General and administrative	3,407	2,966	10,562	8,595
Total operating expenses	12,431	7,918	37,528	22,001
Loss from operations	(12,431)	(7,918)	(37,528)	(22,001)
Other expense:
Interest expense, net	(250)	(104)	(738)	(261)
Other expense, net	(11)	(4)	(34)	(325)
Other expense, net	(261)	(108)	(772)	(586)
Net loss	$ (12,692)	$ (8,026)	$ (38,300)	$ (22,587)
Net loss per share attributable to common stockholders—basic and diluted	$ (0.17)	$ (0.22)	$ (0.61)	$ (0.77)
Weighted-average common shares outstanding—basic and diluted	76,658,487	36,260,973	63,283,268	29,317,787
Net loss	$ (12,692)	$ (8,026)	$ (38,300)	$ (22,587)
Comprehensive loss	$ (12,692)	$ (8,026)	$ (38,300)	$ (22,587)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2019	$ 17,198	$ 25	$ 182,117	$ (164,944)
Balance, Shares at Dec. 31, 2019		24,735,009
Issuance of common stock, net of issuance costs	20,387	$ 13	20,374
Issuance of common stock, net of issuance costs, shares		13,211,265
Exercise of common stock options	18		18
Exercise of common stock options, shares		11,928
Issuance of common stock through employee stock purchase plan ("ESPP")	27		27
Issuance of common stock through employee stock purchase plan ("ESPP"), shares		20,003
Issuance of common stock through release of restricted stock units ("RSUs"), shares		140,720
Stock-based compensation	3,136		3,136
Net loss	(22,587)			(22,587)
Balance at Sep. 30, 2020	18,179	$ 38	205,672	(187,531)
Balance, Shares at Sep. 30, 2020		38,118,925
Balance at Jun. 30, 2020	18,373	$ 32	197,846	(179,505)
Balance, Shares at Jun. 30, 2020		32,224,734
Issuance of common stock, net of issuance costs	6,729	$ 6	6,723
Issuance of common stock, net of issuance costs, shares		5,894,191
Stock-based compensation	1,103		1,103
Net loss	(8,026)			(8,026)
Balance at Sep. 30, 2020	18,179	$ 38	205,672	(187,531)
Balance, Shares at Sep. 30, 2020		38,118,925
Balance at Dec. 31, 2020	$ 22,569	$ 51	220,307	(197,789)
Balance, Shares at Dec. 31, 2020	50,821,361	50,821,361
Issuance of common stock and accompanying warrants, net of issuance costs	$ 38,894	$ 29	38,865
Issuance of common stock and accompanying warrants, net of issuance costs, shares		29,067,050
Issuance of common stock through employee stock purchase plan ("ESPP")	5		5
Issuance of common stock through employee stock purchase plan ("ESPP"), shares		4,206
Issuance of common stock through release of restricted stock units ("RSUs"), shares		248,111
Stock-based compensation	2,862		2,862
Net loss	(38,300)			(38,300)
Balance at Sep. 30, 2021	$ 26,030	$ 80	262,039	(236,089)
Balance, Shares at Sep. 30, 2021	80,140,728	80,140,728
Balance at Jun. 30, 2021	$ 12,267	$ 59	235,605	(223,397)
Balance, Shares at Jun. 30, 2021		58,782,984
Issuance of common stock and accompanying warrants, net of issuance costs	25,420	$ 21	25,399
Issuance of common stock and accompanying warrants, net of issuance costs, shares		21,357,744
Stock-based compensation	1,035		1,035
Net loss	(12,692)			(12,692)
Balance at Sep. 30, 2021	$ 26,030	$ 80	$ 262,039	$ (236,089)
Balance, Shares at Sep. 30, 2021	80,140,728	80,140,728

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (38,300)	$ (22,587)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,862	3,136
Depreciation expense	241	123
Non-cash interest expense	40	20
Non-cash lease expense	281	401
Loss on sale of equipment	9
Changes in assets and liabilities:
Prepaid expenses and other current assets	674	1,846
Other assets	(5)	(50)
Accounts payable	623	(1,920)
Accrued expenses	925	(937)
Operating lease liabilities	(225)	(361)
Net cash used in operating activities	(32,875)	(20,329)
Cash flows from investing activities:
Purchases of property and equipment	(642)
Net cash used in investing activities	(642)
Cash flows from financing activities:
Proceeds from the issuance of common stock and common stock warrants, net of issuance costs	38,891	20,437
Proceeds from exercise of stock options		18
Proceeds from the issuance of stock through ESPP	5	27
Proceeds of loan payable		10,000
Repayment of loan payable		(10,000)
Other		(24)
Net cash provided by financing activities	38,896	20,458
Net increase in cash and cash equivalents	5,379	129
Cash and cash equivalents, beginning of period	35,042	30,007
Cash and cash equivalents, end of period	40,421	30,136
Supplemental disclosures:
Property and equipment purchases included in accounts payable		36
Common stock issuance costs included in accounts payable		50
Debt issuance costs included in accrued expenses	$ 3	$ 172

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Allena Pharmaceuticals, Inc. (the “Company”) is a late-stage clinical biopharmaceutical company dedicated to discovering, developing and commercializing first-in-class, oral biological therapeutics to treat patients with rare and severe metabolic and kidney disorders. The Company’s lead product candidate, reloxaliase (formerly known as ALLN-177), is currently being evaluated in a pivotal Phase 3 clinical program for the treatment of enteric hyperoxaluria, a metabolic disorder characterized by markedly elevated urinary oxalate levels and commonly associated with kidney stones, chronic kidney disease (“CKD”) and other serious kidney disorders. There are currently no approved therapies for the treatment of enteric hyperoxaluria. The Company is also developing ALLN-346 for the treatment of hyperuricemia and gout in the setting of advanced CKD. The Company completed a Phase 1b multiple-ascending dose study in the second quarter of 2021 and recently initiated dosing in two Phase 2a studies. The Company was incorporated under the laws of the State of Delaware on June 24, 2011 and is located in Newton, Massachusetts. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any drug product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations, reliance on third party manufacturers, ability to transition from pilot-scale manufacturing to large-scale production of products and the need to obtain adequate additional financing to fund the development of its product candidates. Liquidity and Going Concern The Company had an accumulated deficit of $ 236.1 million at September 30, 2021 and will require substantial additional capital to fund operations. The future success of the Company is dependent on its ability to identify and develop its product candidates and ultimately upon its ability to attain profitable operations. At September 30, 2021, the Company had $ 40.4 million of cash and cash equivalents. On July 16, 2021, the Company completed a registered direct offering, in which the Company issued and sold 17,416,096 shares of its common stock, pre-funded warrants ("Pre-funded Warrants") to purchase up to an aggregate of 3,941,648 shares of its common stock in lieu of shares of common stock, and warrants ("Warrants") to purchase up to 10,678,872 shares of the Company’s common stock through a securities purchase agreement with several healthcare-focused institutional and accredited investors. The combined price of each share of common stock and accompanying Warrant to purchase one-half of a share of common stock was $ 1.311 per share. The purchase price of each Pre-funded Warrant was $ 1.301 , which was the combined purchase price per share of common stock and accompanying Warrant to purchase one-half of a share of common stock, minus $ 0.01 . Gross proceeds of the transaction were $ 28.0 million. As a result of the registered direct offering, the Company received approximately $ 25.4 million after deducting offering costs. Each Warrant is exercisable for one share of the Company’s common stock at an exercise price of $ 1.25 per share. The Warrants are immediately exercisable and expire on July 16, 2026 . Each Pre-funded Warrant is exercisable for one share of our Common Stock at an exercise price of $ 0.01 per share. All Pre-funded Warrants were exercised on July 16, 2021 . The Company entered into an At Market Issuance Sales Agreement with B. Riley Securities, Inc. (“B. Riley ATM Agreement”) on March 29, 2021. During the second quarter of 2021, the Company issued and sold 1,650,988 shares of its common stock under the B. Riley ATM Agreement at a weighted average price of $ 1.25 per share for net proceeds of approximately $ 1.8 million. During the fourth quarter of 2021 through the filing date of this Quarterly Report, the Company issued and sold 2,430,350 shares of its common stock under the B. Riley ATM Agreement at a weighted average price of $ 1.02 per share for net proceeds of $ 2.4 million. During the first quarter of 2021, the Company issued and sold 6,058,318 shares of its common stock under an At-the Market Equity Offering Sales Agreement with Cowen and Company, LLC ("Cowen ATM Agreement") at a weighted average price of $ 1.99 per share for net proceeds of $ 11.7 million. The Cowen ATM Agreement was terminated at the time the Company entered into the B. Riley ATM Agreement. The Company’s available cash and cash equivalents as of September 30, 2021 are not sufficient to fund the Company’s current operating plan for at least the next twelve months following the filing of this Quarterly Report. The Company requires additional capital to sustain its operations, including its reloxaliase and ALLN-346 development program. Management is exploring opportunities to secure additional funding through equity or debt financings or through collaborations, licensing transactions or other sources. The Company may be unable to obtain equity or debt financings or enter into collaboration or licensing transactions. Market volatility resulting from the COVID-19 pandemic or other factors could also adversely impact the Company’s ability to access capital as and when needed. If the Company is unable to raise capital when needed or on attractive terms, it may decide to delay, reduce or eliminate its research and development programs or future commercialization efforts and its ability to continue operations will be jeopardized. These factors raise substantial doubt about the Company’s ability to continue as a going concern as of the filing date of this Quarterly Report. The Company may implement cost reduction strategies, which may include amending, delaying, limiting, reducing, or terminating one or more of its ongoing or planned clinical trials or development programs of its product candidates. The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC on March 11, 2021. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and September 30, 2020 and cash flows for the nine months ended September 30, 2021 and September 30, 2020. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results for the year ending December 31, 2021, or for any future period. Principles of Consolidation The consolidated financial statements include the accounts of Allena Pharmaceuticals, Inc. and its wholly owned subsidiaries, Allena Pharmaceuticals Security Corporation (“Security Corporation”), which was incorporated in December 2014 , and Allena Pharmaceuticals Ireland Limited, which was incorporated in March 2017 . All intercompany transactions and balances have been eliminated. Fair Value of Financial Instruments Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability between market participants at measurement dates. ASC Topic 820, Fair Value Measurement (“ASC 820”), establishes a three-level valuation hierarchy for instruments measured at fair value. The hierarchy is based on the transparency of inputs to the valuation of an asset or liability as of the measurement date. The hierarchy defines three levels of valuation inputs, of which the first two are considered observable and the last is considered unobservable: Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, expenses and related disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting period. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, management’s judgment of prepaid and accrued research and development expenses and the valuation of share-based awards. Actual results could differ from those estimates. The remainder of the Company’s significant accounting policies are described in the Annual Report filed on Form 10-K for the year ended December 31, 2020 that was filed with the United States Securities and Exchange Commission on March 11, 2021. Warrants The Company accounts for issued warrants either as a liability or equity in accordance with ASC 480-10, Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity (“ASC 480-10”) or ASC 815-40, Accounting for Derivative Financial Instruments Indexed to, and Potentially Settled in, a Company’s Own Stock (“ASC 815-40”). Under ASC 480-10, warrants are considered a liability if they are mandatorily redeemable and they require settlement in cash, other assets, or a variable number of shares. If warrants do not meet liability classification under ASC 480-10, the Company considers the requirements of ASC 815-40 to determine whether the warrants should be classified as a liability or as equity. Under ASC 815-40, contracts that may require settlement for cash are liabilities, regardless of the probability of the occurrence of the triggering event. Liability-classified warrants are measured at fair value on the issuance date and at the end of each reporting period. Any change in the fair value of the warrants after the issuance date is recorded in other expense, net in the consolidated statements of operations as a gain or loss. If warrants do not require liability classification under ASC 815-40, in order to conclude warrants should be classified as equity, the Company assesses whether the warrants are indexed to its common stock and whether the warrants are classified as equity under ASC 815-40 or other applicable GAAP standard. Equity-classified warrants are accounted for at fair value on the issuance date with no changes in fair value recognized after the issuance date. The Warrants and Pre-funded Warrants do not meet the requirements for liability classification under ASC-480-10 or ASC-815-40. Therefore, the Warrants and Pre-funded Warrants were treated as equity at the time of issuance. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify various aspects related to accounting for income taxes. The new guidance became effective for the Company on January 1, 2021 . The adoption of ASU 2019-12 did not have a material impact on the Company’s condensed consolidated financial statements. Recently Issued Accounting Pronouncements In 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires entities to record expected credit losses for certain financial instruments, including trade receivables, as an allowance that reflects the entity's current estimate of credit losses expected to be incurred. For available-for-sale debt securities in unrealized loss positions, ASU 2016-13 requires allowances to be recorded instead of reducing the amortized cost of the investment. ASU 2016-13 is effective for smaller reporting companies on January 1, 2023. Early adoption is permitted. The Company does not expect that the adoption of ASU 2016-13 will have a material impact on its condensed consolidated financial statements. In 2020, the FASB issued ASU 2020-06, Debt -Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40) , simplifies the accounting for convertible debt and convertible preferred stock by removing the requirements to separately present certain conversion features in equity. In addition, the amendments in the ASU also simplify the guidance in ASC 815-40, Derivatives and Hedging: Contracts in Entity’s Own Equity (“ASU 2020-06”), by removing certain criteria that must be satisfied in order to classify a contract as equity, which is expected to decrease the number of freestanding instruments and embedded derivatives accounted for as assets or liabilities. Finally, the amendments revise the guidance on calculating earnings per share, requiring use of the if-converted method for all convertible instruments and rescinding an entity’s ability to rebut the presumption of share settlement for instruments that may be settled in cash or other assets. ASU 2020-06 is effective for smaller reporting companies on January 1, 2022. Early adoption is permitted. The Company does not expect that the adoption of ASU 2020-06 will have a material impact on its condensed consolidated financial statements.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	3. Net Loss per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. The Company has computed diluted net loss per common share after giving consideration to all potentially dilutive common shares, including options to purchase common stock, restricted stock units, common stock issuable upon the conversion of outstanding debt and warrants to purchase common stock, outstanding during the period determined using the treasury-stock and if-converted methods, except where the effect of including such securities would be antidilutive. Because the Company has reported net losses since inception, these potential common shares have been anti-dilutive and basic and diluted loss per share have been the same. Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ ( 12,692 ) $ ( 8,026 ) $ ( 38,300 ) $ ( 22,587 ) Net loss attributable to common stockholders $ ( 12,692 ) $ ( 8,026 ) $ ( 38,300 ) $ ( 22,587 ) Denominator: Weighted-average common shares—basic and diluted 76,658,487 36,260,973 63,283,268 29,317,787 Net loss per share attributable to common $ ( 0.17 ) $ ( 0.22 ) $ ( 0.61 ) $ ( 0.77 ) The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): Nine Months Ended September 30, 2021 2020 Stock options 7,188,457 3,678,241 Restricted stock units 372,166 547,319 Warrants 10,687,912 9,040 Common stock issuable upon conversion of outstanding debt 2,439,024 2,439,024 Total 20,687,559 6,673,624

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following tables present information about the Company’s financial assets and liabilities that have been measured at fair value at September 30, 2021 and December 31, 2020, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): Description September 30, Quoted Significant Significant Assets: Money market funds, included in cash and cash equivalents $ 39,421 $ 39,421 $ — $ — Total assets $ 39,421 $ 39,421 $ — $ — Description December 31, Quoted Significant Significant Assets: Money market funds, included in cash and cash equivalents $ 34,698 $ 34,698 $ — $ — Total assets $ 34,698 $ 34,698 $ — $ — At September 30, 2021 and December 31, 2020, substantially all of the Company’s cash equivalents were comprised of money market funds. There were no changes to the valuation methods during the three months ended September 30, 2021 and the year ended December 31, 2020. There were no transfers within the fair value hierarchy during the three and nine months ended September 30, 2021 and the year ended December 31, 2020. The carrying amounts reflected in the consolidated balance sheets for cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their carrying values. The Company believes the terms of the loan payable reflect current market conditions for an instrument with similar terms and maturity and therefore the carrying value of the Company’s debt approximates its fair value based on Level 3 of the fair value hierarchy.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of the following (in thousands): September 30, December 31, Payroll and employee-related expenses $ 2,137 $ 1,945 Third-party research and development expenses 1,661 984 Professional fees 306 250 Loan interest 239 242 Other 3 — Total accrued expenses $ 4,346 $ 3,421

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies The Company is a party to an operating lease for approximately 11,691 square feet of laboratory and office space in Sudbury, MA (Sudbury Lease). The Sudbury Lease expires on February 28, 2026 . The Company has a one-time option to cancel the lease effective February 28, 2023 for any reason or no reason at all. Annualized base rent for the Sudbury Lease is approximately $ 0.3 million. Maturities of the Company’s operating lease liabilities in accordance with ASC 842 as of September 30, 2021 are as follows (in thousands): Remainder of 2021 $ 75 2022 300 2023 227 Total maturities 602 Less: Amount representing interest ( 28 ) Present value of operating lease liabilities $ 574 Lease costs included in the Company’s condensed consolidated statements of operations and comprehensive loss was $ 0.1 million and $ 0.3 million for the three and nine months ended September 30, 2021 and 2020, respectively. The Company’s operating leases had a weighted average remaining lease term of 1.5 years and a weighted average discount rate of 5.5 % at September 30, 2021. The Company is also a party to an operating lease for approximately 6,055 square feet of office space in Newton, MA (Newton Lease). The Newton Lease terminates on the last day of the month following the month either party notifies the other that the term of the lease shall end. The annualized base rent for the Newton Lease is approximately $ 0.3 million. Due to the short nature of the minimum lease term of the Newton Lease, the Newton Lease was not considered as an operating lease liability in accordance with ASC 842 as of September 30, 2021 and December 31, 2020.

Loan and Security Agreement

Loan and Security Agreement	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Loan and Security Agreement	7. Loan and Security Agreement On June 29, 2018, the Company entered into a loan agreement with Pacific Western Bank (“PWB Loan Agreement”) providing up to $ 12.0 million of borrowings, of which $ 10.0 million was advanced on June 29, 2018. The remaining $ 2.0 million of borrowings were available to the Company through one additional advance request until December 31, 2019. Borrowings were secured by a lien on all Company assets, excluding intellectual property, and amounts borrowed had a floating per annum interest rate of the greater of 5.0 % or the prime rate. The PWB Loan Agreement had a term of 48 months and an interest only period of 18 months . Upon the expiration of the interest only period on December 31, 2019 , amounts borrowed were to be repaid over 30 equal monthly payments of principal plus accrued but unpaid interest. At its option, the Company could prepay all, but not less than all, of the outstanding borrowings subject to a prepayment premium as defined in the PWB Loan Agreement. Upon the closing of one or more financings in which the Company receives aggregate gross proceeds of at least $ 25 million, a success fee of $ 300,000 would be due and payable to PWB. As a result of the gross proceeds of $ 15.0 million received from the registered direct offering completed on June 5, 2020, combined with $ 10.0 million of gross proceeds received from the registered direct offering completed in June 2019, and $ 2.7 million of gross proceeds received through the At-the-Market offering completed in December 2019, the conditions required to trigger the success fee were fulfilled and the success fee was paid to PWB at the time of the closing of the registered direct offering in June 2020. The success fee was recorded as other expense on the Company’s condensed consolidated statements of operations and comprehensive loss at the time the registered direct offering was completed. On September 29, 2020, the Company terminated the PWB Loan Agreement and repaid the $ 7.0 million outstanding principal to PWB. At the time the Company terminated the PWB Loan Agreement, the requirement to make a prepayment premium with respect to the Company prepaying the remaining outstanding borrowings under the PWB Loan Agreement had lapsed and no prepayment penalty payment was required upon termination of the PWB Loan Agreement.

Convertible Debt Agreement

Convertible Debt Agreement	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Convertible Debt Agreement	8. Convertible Debt Agreement On September 29, 2020, the Company entered into a loan and security agreement with Pontifax Medison Finance (Israel) L.P. and Pontifax Medison Finance (Cayman) L.P. (together “Pontifax”) (“Pontifax Agreement”) providing up to $ 25.0 million of borrowings through three facilities of a term loan. An initial loan (“Initial Loan”) of $ 10.0 million was advanced on September 29, 2020 (“Closing Date”). An additional $ 5.0 million credit line (“Credit Line”) was available to the Company for withdrawal for a period of 12 months from the Closing Date. The Company paid a fee of 1.0 % per annum to Pontifax for the daily average amount not withdrawn under the Credit Line. A third installment loan (“Third Installment Loan”) of $ 10.0 million was conditioned upon achievement of one of the following milestones by no later than 15 months from the Closing Date: (i) the Company receives non-contingent, non-refundable gross proceeds from one or more equity financings and/or strategic partnerships, in each case consummated following the Closing Date, in the aggregate amount of at least $ 15.0 million for all such equity financings and strategic partnerships or (ii) the 65 th patient has been enrolled in the URIROX-2 trial. During the three months ended December 31, 2020, the additional $ 10 million under the Third Installment Loan became available to the Company when the milestone of at least $ 15 million of gross proceeds from equity financings was achieved. Upon withdrawal of the Third Installment Loan, the Company shall pay Pontifax a one-time fee of 1.0 % of the Third Installment Loan. As of September 30, 2021, the Company had not withdrawn any amounts available under the Credit Line or the Third Installment Loan. The availability to withdraw amounts available under the Credit Line expired unused on September 29, 2021 . Amounts outstanding under the Pontifax Agreement have a fixed interest rate of 9.0 % per annum. The Pontifax Agreement has a term of 48 months and an interest only period of 24 months . Upon the expiration of the interest only period on September 29, 2022 , amounts borrowed will be repaid over eight equal quarterly payments of principal and interest. At its option, the Company may prepay all or part of the outstanding borrowings at any time without any prepayment premium or penalty. The Pontifax Agreement contains negative covenants restricting the Company’s activities, including limitations on dispositions, mergers or acquisitions, incurring indebtedness or liens, paying dividends or making investments and certain other business transactions. There are no financial covenants associated with the Pontifax Agreement. The obligations under the Pontifax Agreement are subject to acceleration upon the occurrence of specified events of default, including a material adverse change in the Company’s business, operations or financial or other condition. The Company has determined that the risk of subjective acceleration under the material adverse events clause is remote and therefore has classified the outstanding principal based on scheduled principal payments. Pontifax, at its option, has the right to convert at any time any portion of the then outstanding borrowings and all accrued but unpaid interest into shares of the Company’s common stock, at the applicable conversion price. The conversion price for borrowings outstanding under the Pontifax Agreement is fixed at $ 4.10 per share. If the Company consummates a stock split, stock combination, reclassification payment of stock dividend, recapitalization or other similar transaction (each a “Stock Event”), then the applicable conversion price will be proportionately increased or decreased as necessary to reflect the proportionate change in shares of the Company’s common stock issued and outstanding as a result of such Stock Event. The Company has the right to convert at any time any portion of the then outstanding borrowings and all accrued but unpaid interest into shares of the Company’s common stock, at the applicable conversion price, subject to the fulfillment of both of the following conditions: (i) during a period of 30 consecutive trading days prior to the date on which the Company provides notice of the exercise of its conversion right, the closing price of the Company’s common stock was higher than 1.4 times the applicable conversion price of the term loans on at least 20 trading days, including on the trading day preceding the date on which the Company provides notice of the exercise of its conversion right, (ii) the number of shares of common stock issuable upon conversion by the Company shall not exceed the average weekly number of shares of the Company’s common stock traded on the stock market for the four weeks immediately preceding the date on which the Company provides notice of the exercise of its conversion right. The shares of the Company’s common stock issued upon conversion will be free of any restrictions and the Company is required to hold at all times a sufficient number of authorized, unreserved and unissued shares of its common stock required to settle any such conversion. As of September 30, 2021, the Company has reserved 2,439,024 shares of its common stock for conversion of the outstanding debt balance. The Company evaluated the Pontifax Agreement for embedded features that require bifurcation, noting certain features were required to be bifurcated, but were concluded to be de minimis in value at September 30, 2021 and December 31, 2020. The Company determined the conversion feature was not required to be accounted for separately. The Company concluded that the embedded conversion option is not subject to separate accounting pursuant to either the cash conversion guidance or the beneficial conversion feature guidance. The minimum aggregate future loan and interest payments at September 30, 2021 are as follows (in thousands): Years Ending December 31, 2021 $ 239 2022 1,927 2023 5,015 2024 4,880 Total minimum payments $ 12,061 Less: Amount representing interest ( 2,061 ) Less: Discount ( 107 ) Less: Current portion — Loan payable, net of current portion $ 9,893

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity Common Stock During the first quarter of 2021, the Company issued and sold 6,058,318 shares of its common stock under the Cowen ATM Agreement at a weighted average price of $ 1.99 per share for net proceeds of $ 11.7 million. During the second quarter of 2021, the Company issued and sold 1,650,988 shares of its common stock under the B. Riley ATM Agreement at a weighted average price of $ 1.25 per share for net proceeds of $ 1.8 million. During the fourth quarter of 2021 through the filing date of this Quarterly Report, the Company issued and sold 2,430,350 shares of its common stock under the B. Riley ATM Agreement at a weighted average price of $ 1.02 per share for net proceeds of $ 2.4 million. On July 16, 2021, the Company completed a registered direct offering, in which the Company issued and sold 17,416,096 shares of its common stock, pre-funded warrants to purchase up to an aggregate of 3,941,648 shares of its common stock in lieu of shares of common stock and warrants to purchase up to 10,678,872 shares of the Company’s common stock through a securities purchase agreement. The combined price of each share of common stock and accompanying Warrant to purchase one-half of a share of common stock was $ 1.311 . The purchase price of each Pre-funded Warrant was $ 1.301 , which was the combined purchase price per share of common stock and accompanying Warrant, minus $ 0.01 . Gross proceeds of the transaction were $ 28.0 million. As a result of the registered direct offering, the Company received approximately $ 25.4 million after deducting estimated offering costs. Each Warrant is exercisable for one share of the Company’s common stock at an exercise price of $ 1.25 per share. The Warrants are immediately exercisable and expire on July 16, 2026 . Each Pre-funded Warrant is exercisable for one share of our common stock at an exercise price of $ 0.01 per share. All Pre-Funded Warrants were exercised on July 16, 2021 . The holders of common stock are entitled to one vote for each share held . Common stockholders are not entitled to receive dividends, unless declared by the Board of Directors. The Company has reserved for future issuances the following shares of common stock as of September 30, 2021 and December 31, 2020: September 30, December 31, Stock options and restricted stock units 8,744,479 5,359,736 Common stock issuable upon conversion of outstanding debt 2,439,024 2,439,024 Employee stock purchase plan 332,704 336,910 Warrants 10,687,912 9,040 Total 22,204,119 8,144,710

Stock Incentive Plan

Stock Incentive Plan	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plan	10. Stock Incentive Plan On October 31, 2017 , the Company adopted the 2017 Stock Option and Incentive Plan (“2017 Plan”). Upon the adoption of the 2017 Plan, no further grants would be made under the 2011 Stock Incentive Plan (“2011 Plan”). The 2017 Plan initially provided for the grant of awards for 2,038,021 shares of common stock. In addition to the shares available for grant under the 2017 Plan, shares underlying any awards outstanding under the 2011 Plan as of the October 31, 2017 that are cancelled, forfeited or otherwise terminated without being exercised will be available for future grant under the 2017 Plan. The 2017 Plan also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 Plan on January 1 of each year. The number of shares added each year will be equal to the lesser of: (i) 4 % of the outstanding shares on the immediately preceding December 31 or (ii) such amount as determined by the Compensation Committee of the Board of Directors. On January 1, 2019, 2020 and 2021, the shares available for grant under the 2017 Plan were automatically increased by 832,361 , 989,400 and 2,032,854 shares, respectively. All of the Company’s employees, officers, directors, consultants and advisors are eligible to be granted options, restricted stock units (“RSUs”), and other share-based awards under the terms of the 2017 Plan. As of September 30, 2021, 430,856 shares of common stock were available for future grant under the 2017 Plan. On January 22, 2021, the Company adopted the 2021 Inducement Equity Plan (“2021 Plan”). The 2021 Plan provides for the grant of awards for 1,600,000 shares of common stock. The purpose of the 2021 plan is to enable the Company to grant equity awards to induce highly qualified prospective officers and employees who are not currently employed by the Company to accept employment and provide them with an equity interest in the Company. The Company is utilizing the 2021 Plan for awards the Company may make without stockholder approval as an inducement pursuant to Rule 5635(c)(4) of the Marketplace Rules of the Nasdaq Stock Market, Inc. As of September 30, 2021, 753,000 shares of common stock were available for future grant under the 2021 Plan. All stock option grants are nonstatutory stock options except option grants to employees (including officers and directors) intended to qualify as incentive stock options under the Internal Revenue Code of 1986, as amended. Incentive stock options may not be granted at less than the fair market value of the Company’s common stock on the date of grant, as determined in good faith by the Board of Directors at its sole discretion. Nonqualified stock options may be granted at an exercise price established by the Board of Directors at its sole discretion (which has not been less than fair market value on the date of grant) and the vesting periods may vary. Vesting periods are generally four years and are determined by the Board of Directors or a delegated subcommittee. Stock options become exercisable as they vest. Options granted under both the 2011 Plan and 2017 Plan expire no more than 10 years from the date of grant. Stock-based compensation expense included in the Company’s statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 329 $ 337 $ 879 $ 1,046 General and administrative 706 766 1,983 2,090 Total $ 1,035 $ 1,103 $ 2,862 $ 3,136 The fair value of each stock option granted to employees and directors during the three and nine months ended September 30, 2021 was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions: Three Months Ended Nine Months Ended Risk-free interest rate 0.7 %- 1.1 % 0.4 %- 1.4 % Expected dividend yield —% —% Expected term (in years) 5.5 - 7.0 5.0 - 7.0 Expected volatility 92 %- 95 % 92 %- 95 % The Company did no t grant any stock options during the three and nine months ended September 30, 2020. A summary of the stock option activity under the 2011, 2017 and 2021 Plans is as follows: Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2020 4,110,691 $ 3.89 7.3 $ 124 Granted 3,341,350 1.87 Exercised — — Cancelled ( 263,584 ) 6.92 Outstanding at September 30, 2021 7,188,457 $ 2.84 7.9 $ 24 Exercisable at September 30, 2021 3,024,808 $ 3.68 6.2 $ 24 As of September 30, 2021, total unrecognized stock-based compensation expense relating to unvested stock options was $ 6.4 million. This amount is expected to be recognized over a weighted-average period of 2.6 years. Restricted Stock Units (RSUs) In December 2020, the Company awarded 620,277 RSUs to employees of the Company. 248,111 shares of common stock were issued on May 10, 2021 upon vesting of a portion of the RSUs. The remaining RSUs vest on November 10, 2021. The RSUs are generally forfeited if the employment relationship terminates with the Company prior to vesting. For the three and nine months ended September 30, 2021, the Company recognized $ 0.2 million and $ 0.6 million of stock-based compensation expense, respectively, related to these awards. As of September 30, 2021, the total remaining unrecognized compensation cost related to all unvested RSUs amounted to $ 0.1 million, which is expected to be recognized during the remainder of 2021. A summary of the status of nonvested RSUs as of September 30, 2021 and the changes during the nine months then ended are presented below: Shares Weighted-Average Nonvested at December 31, 2020 620,277 $ 1.29 Granted — — Vested ( 248,111 ) 1.29 Forfeited — — Nonvested at September 30, 2021 372,166 $ 1.29

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 Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC on March 11, 2021. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and September 30, 2020 and cash flows for the nine months ended September 30, 2021 and September 30, 2020. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results for the year ending December 31, 2021, or for any future period.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Allena Pharmaceuticals, Inc. and its wholly owned subsidiaries, Allena Pharmaceuticals Security Corporation (“Security Corporation”), which was incorporated in December 2014 , and Allena Pharmaceuticals Ireland Limited, which was incorporated in March 2017 . All intercompany transactions and balances have been eliminated.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability between market participants at measurement dates. ASC Topic 820, Fair Value Measurement (“ASC 820”), establishes a three-level valuation hierarchy for instruments measured at fair value. The hierarchy is based on the transparency of inputs to the valuation of an asset or liability as of the measurement date. The hierarchy defines three levels of valuation inputs, of which the first two are considered observable and the last is considered unobservable: Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, expenses and related disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting period. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, management’s judgment of prepaid and accrued research and development expenses and the valuation of share-based awards. Actual results could differ from those estimates. The remainder of the Company’s significant accounting policies are described in the Annual Report filed on Form 10-K for the year ended December 31, 2020 that was filed with the United States Securities and Exchange Commission on March 11, 2021.
Warrants	Warrants The Company accounts for issued warrants either as a liability or equity in accordance with ASC 480-10, Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity (“ASC 480-10”) or ASC 815-40, Accounting for Derivative Financial Instruments Indexed to, and Potentially Settled in, a Company’s Own Stock (“ASC 815-40”). Under ASC 480-10, warrants are considered a liability if they are mandatorily redeemable and they require settlement in cash, other assets, or a variable number of shares. If warrants do not meet liability classification under ASC 480-10, the Company considers the requirements of ASC 815-40 to determine whether the warrants should be classified as a liability or as equity. Under ASC 815-40, contracts that may require settlement for cash are liabilities, regardless of the probability of the occurrence of the triggering event. Liability-classified warrants are measured at fair value on the issuance date and at the end of each reporting period. Any change in the fair value of the warrants after the issuance date is recorded in other expense, net in the consolidated statements of operations as a gain or loss. If warrants do not require liability classification under ASC 815-40, in order to conclude warrants should be classified as equity, the Company assesses whether the warrants are indexed to its common stock and whether the warrants are classified as equity under ASC 815-40 or other applicable GAAP standard. Equity-classified warrants are accounted for at fair value on the issuance date with no changes in fair value recognized after the issuance date. The Warrants and Pre-funded Warrants do not meet the requirements for liability classification under ASC-480-10 or ASC-815-40. Therefore, the Warrants and Pre-funded Warrants were treated as equity at the time of issuance.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify various aspects related to accounting for income taxes. The new guidance became effective for the Company on January 1, 2021 . The adoption of ASU 2019-12 did not have a material impact on the Company’s condensed consolidated financial statements.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires entities to record expected credit losses for certain financial instruments, including trade receivables, as an allowance that reflects the entity's current estimate of credit losses expected to be incurred. For available-for-sale debt securities in unrealized loss positions, ASU 2016-13 requires allowances to be recorded instead of reducing the amortized cost of the investment. ASU 2016-13 is effective for smaller reporting companies on January 1, 2023. Early adoption is permitted. The Company does not expect that the adoption of ASU 2016-13 will have a material impact on its condensed consolidated financial statements. In 2020, the FASB issued ASU 2020-06, Debt -Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40) , simplifies the accounting for convertible debt and convertible preferred stock by removing the requirements to separately present certain conversion features in equity. In addition, the amendments in the ASU also simplify the guidance in ASC 815-40, Derivatives and Hedging: Contracts in Entity’s Own Equity (“ASU 2020-06”), by removing certain criteria that must be satisfied in order to classify a contract as equity, which is expected to decrease the number of freestanding instruments and embedded derivatives accounted for as assets or liabilities. Finally, the amendments revise the guidance on calculating earnings per share, requiring use of the if-converted method for all convertible instruments and rescinding an entity’s ability to rebut the presumption of share settlement for instruments that may be settled in cash or other assets. ASU 2020-06 is effective for smaller reporting companies on January 1, 2022. Early adoption is permitted. The Company does not expect that the adoption of ASU 2020-06 will have a material impact on its condensed consolidated financial statements.

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ ( 12,692 ) $ ( 8,026 ) $ ( 38,300 ) $ ( 22,587 ) Net loss attributable to common stockholders $ ( 12,692 ) $ ( 8,026 ) $ ( 38,300 ) $ ( 22,587 ) Denominator: Weighted-average common shares—basic and diluted 76,658,487 36,260,973 63,283,268 29,317,787 Net loss per share attributable to common $ ( 0.17 ) $ ( 0.22 ) $ ( 0.61 ) $ ( 0.77 )
Summary of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share	The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): Nine Months Ended September 30, 2021 2020 Stock options 7,188,457 3,678,241 Restricted stock units 372,166 547,319 Warrants 10,687,912 9,040 Common stock issuable upon conversion of outstanding debt 2,439,024 2,439,024 Total 20,687,559 6,673,624

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value	The following tables present information about the Company’s financial assets and liabilities that have been measured at fair value at September 30, 2021 and December 31, 2020, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): Description September 30, Quoted Significant Significant Assets: Money market funds, included in cash and cash equivalents $ 39,421 $ 39,421 $ — $ — Total assets $ 39,421 $ 39,421 $ — $ — Description December 31, Quoted Significant Significant Assets: Money market funds, included in cash and cash equivalents $ 34,698 $ 34,698 $ — $ — Total assets $ 34,698 $ 34,698 $ — $ —

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): September 30, December 31, Payroll and employee-related expenses $ 2,137 $ 1,945 Third-party research and development expenses 1,661 984 Professional fees 306 250 Loan interest 239 242 Other 3 — Total accrued expenses $ 4,346 $ 3,421

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Operating Leased Assets [Line Items]
Schedule of Maturities of Operating Lease Liabilities	Maturities of the Company’s operating lease liabilities in accordance with ASC 842 as of September 30, 2021 are as follows (in thousands): Remainder of 2021 $ 75 2022 300 2023 227 Total maturities 602 Less: Amount representing interest ( 28 ) Present value of operating lease liabilities $ 574

Convertible Debt Agreement (Tab

Convertible Debt Agreement (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Summary of Minimum Aggregate Future Loan and Interest Payments	The minimum aggregate future loan and interest payments at September 30, 2021 are as follows (in thousands): Years Ending December 31, 2021 $ 239 2022 1,927 2023 5,015 2024 4,880 Total minimum payments $ 12,061 Less: Amount representing interest ( 2,061 ) Less: Discount ( 107 ) Less: Current portion — Loan payable, net of current portion $ 9,893

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Summary of Shares of Common Stock Reserved	The Company has reserved for future issuances the following shares of common stock as of September 30, 2021 and December 31, 2020: September 30, December 31, Stock options and restricted stock units 8,744,479 5,359,736 Common stock issuable upon conversion of outstanding debt 2,439,024 2,439,024 Employee stock purchase plan 332,704 336,910 Warrants 10,687,912 9,040 Total 22,204,119 8,144,710

Stock Incentive Plan (Tables)

Stock Incentive Plan (Tables)	9 Months Ended
	Sep. 30, 2021
Summary of Stock-based Compensation Expense	Stock-based compensation expense included in the Company’s statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 329 $ 337 $ 879 $ 1,046 General and administrative 706 766 1,983 2,090 Total $ 1,035 $ 1,103 $ 2,862 $ 3,136
Summary of Stock Option Activity	The Company did no t grant any stock options during the three and nine months ended September 30, 2020. A summary of the stock option activity under the 2011, 2017 and 2021 Plans is as follows: Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2020 4,110,691 $ 3.89 7.3 $ 124 Granted 3,341,350 1.87 Exercised — — Cancelled ( 263,584 ) 6.92 Outstanding at September 30, 2021 7,188,457 $ 2.84 7.9 $ 24 Exercisable at September 30, 2021 3,024,808 $ 3.68 6.2 $ 24
Restricted Stock Units (RSUs)
Summary of Nonvested RSUs	A summary of the status of nonvested RSUs as of September 30, 2021 and the changes during the nine months then ended are presented below: Shares Weighted-Average Nonvested at December 31, 2020 620,277 $ 1.29 Granted — — Vested ( 248,111 ) 1.29 Forfeited — — Nonvested at September 30, 2021 372,166 $ 1.29
Employees and Directors
Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Stock Options	The fair value of each stock option granted to employees and directors during the three and nine months ended September 30, 2021 was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions: Three Months Ended Nine Months Ended Risk-free interest rate 0.7 %- 1.1 % 0.4 %- 1.4 % Expected dividend yield —% —% Expected term (in years) 5.5 - 7.0 5.0 - 7.0 Expected volatility 92 %- 95 % 92 %- 95 %

Nature of Business - Additional

Nature of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 12, 2021	Jul. 16, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Accumulated deficit					$ 236,089	$ 197,789
Cash and cash equivalents					$ 40,421	$ 35,042
B. Riley ATM Agreement | At Market Issuance Sales Agreement
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs, shares			1,650,988
Proceeds from the issuance of common stock, net of issuance costs			$ 1,800
Weighted average price of common stock shares sold and issued			$ 1.25
B. Riley ATM Agreement | At Market Issuance Sales Agreement | Subsequent Event
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs, shares	2,430,350
Proceeds from the issuance of common stock, net of issuance costs	$ 2,400
Weighted average price of common stock shares sold and issued	$ 1.02
Cowen ATM Agreement
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs, shares				6,058,318
Proceeds from the issuance of common stock, net of issuance costs				$ 11,700
Weighted average price of common stock shares sold and issued				$ 1.99
Direct Offering
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs, shares		17,416,096
Maximum aggregate warrant to purchase number of shares of common stock		10,678,872
Difference in combined price of each share of common stock and accompanying warrant and purchase price of prefunded warrant per share		$ 0.01
Gross proceeds of the transaction		$ 28,000
Proceeds from the issuance of common stock, net of issuance costs		$ 25,400
Each warrant exercisable shares		1
Purchase price / Exercise price of warrant		$ 1.25
Warrant exercisable date		Jul. 16, 2026
Combined price of each share of common stock and accompanying warrant to purchase one-half price per share		$ 1.311
Direct Offering | Pre-Funded Warrant
Class of Stock [Line Items]
Maximum aggregate warrant to purchase number of shares of common stock		3,941,648
Purchase price of warrant		$ 1.301
Each warrant exercisable shares		1
Purchase price / Exercise price of warrant		$ 0.01
Warrant exercisable date		Jul. 16, 2021

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	2014-12
ASU 2019-12
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
Allena Pharmaceuticals Security Corporation
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	2014-12
Allena Pharmaceuticals Ireland Limited
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	2017-03

Net Loss per Share - Summary of

Net Loss per Share - Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (12,692)	$ (8,026)	$ (38,300)	$ (22,587)
Net loss attributable to common stockholders	$ (12,692)	$ (8,026)	$ (38,300)	$ (22,587)
Denominator:
Weighted-average common shares—basic and diluted	76,658,487	36,260,973	63,283,268	29,317,787
Net loss per share attributable to common stockholders—basic and diluted	$ (0.17)	$ (0.22)	$ (0.61)	$ (0.77)

Net Loss per Share - Summary _2

Net Loss per Share - Summary of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	20,687,559	6,673,624
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	7,188,457	3,678,241
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	372,166	547,319
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	10,687,912	9,040
Common Stock Issuable Upon Conversion of Outstanding Debt
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	2,439,024	2,439,024

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 39,421	$ 34,698
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	39,421	34,698
Money market funds, included in cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money market funds, included in cash and cash equivalents	39,421	34,698
Money market funds, included in cash and cash equivalents | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money market funds, included in cash and cash equivalents	$ 39,421	$ 34,698

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in valuation methods or transfers	$ 0		$ 0
Transfers within fair value hierarchy	$ 0	$ 0	$ 0

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Payroll and employee-related expenses	$ 2,137	$ 1,945
Third-party research and development expenses	1,661	984
Professional fees	306	250
Loan interest	239	242
Other	3
Total accrued expenses	$ 4,346	$ 3,421

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)ft²	Sep. 30, 2020USD ($)
Operating Leased Assets [Line Items]
Lease costs	$ 0.1	$ 0.1	$ 0.3	$ 0.3
Operating lease, weighted average remaining lease term	1 year 6 months		1 year 6 months
Operating lease, weighted average discount rate	5.50%		5.50%
Sudbury, MA
Operating Leased Assets [Line Items]
Rentable office space under operating lease | ft²			11,691
Base rent for office space			$ 0.3
Operating lease expiration date			Feb. 28, 2026
Right to terminate description			The Company has a one-time option to cancel the lease effective February 28, 2023 for any reason or no reason at all.
Newton, MA
Operating Leased Assets [Line Items]
Rentable office space under operating lease | ft²			6,055
Base rent for office space			$ 0.3
Right to terminate description			The Newton Lease terminates on the last day of the month following the month either party notifies the other that the term of the lease shall end.

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Maturities of Operating Lease Liabilities (Details) - ASC 842 $ in Thousands	Sep. 30, 2021USD ($)
Lessee Lease Description [Line Items]
Remainder of 2021	$ 75
2022	300
2023	227
Total maturities	602
Less: Amount representing interest	(28)
Present value of operating lease liabilities	$ 574

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Details) - USD ($)	Sep. 29, 2020	Jun. 05, 2020	Jun. 29, 2018	Dec. 31, 2019	Jun. 30, 2019	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Loan agreement, advanced amount							$ 10,000,000
Loan and Security Agreement | PWB
Debt Instrument [Line Items]
Loan agreement, maximum borrowing capacity			$ 12,000,000
Loan agreement, advanced amount			10,000,000
Loan agreement, remaining borrowing capacity			$ 2,000,000
Loan agreement, interest rate above prime rate			5.00%
Loan agreement, term			48 months
Loan agreement, interest only payment period			18 months
Expiration of interest only period			Dec. 31, 2019
Loan agreement, number of monthly payments			30 months
Loan agreement, frequency of payments						monthly
Aggregate gross proceeds for success fee to be paid			$ 25,000,000
Success fee payable			$ 300,000
Repayment of outstanding principal balance	$ 7,000,000
Direct Offering
Debt Instrument [Line Items]
Gross proceeds from issuance of common stock		$ 15,000,000			$ 10,000,000
At-the-Market Offering
Debt Instrument [Line Items]
Gross proceeds from issuance of common stock				$ 2,700,000

Convertible Debt Agreement - Ad

Convertible Debt Agreement - Additional Information (Details)	Sep. 29, 2020USD ($)TradingDayFacilityInstallment$ / shares	Dec. 31, 2020USD ($)shares	Sep. 30, 2021shares	Sep. 30, 2020USD ($)
Debt Instrument [Line Items]
Loan agreement, advanced amount				$ 10,000,000
Shares of common stock reserved for future issuances | shares		8,144,710	22,204,119
Common Stock Issuable Upon Conversion of Outstanding Debt
Debt Instrument [Line Items]
Shares of common stock reserved for future issuances | shares		2,439,024	2,439,024
Loan and Security Agreement
Debt Instrument [Line Items]
Debt instrument, terms of conversion description			The Company has the right to convert at any time any portion of the then outstanding borrowings and all accrued but unpaid interest into shares of the Company’s common stock, at the applicable conversion price, subject to the fulfillment of both of the following conditions: (i) during a period of 30 consecutive trading days prior to the date on which the Company provides notice of the exercise of its conversion right, the closing price of the Company’s common stock was higher than 1.4 times the applicable conversion price of the term loans on at least 20 trading days, including on the trading day preceding the date on which the Company provides notice of the exercise of its conversion right, (ii) the number of shares of common stock issuable upon conversion by the Company shall not exceed the average weekly number of shares of the Company’s common stock traded on the stock market for the four weeks immediately preceding the date on which the Company provides notice of the exercise of its conversion right.
Debt instrument conversion threshold consecutive trading days | TradingDay	30
Loan and Security Agreement | Minimum
Debt Instrument [Line Items]
Debt instrument conversion threshold trading days | TradingDay	20
Loan and Security Agreement | Pontifax
Debt Instrument [Line Items]
Loan agreement, maximum borrowing capacity	$ 25,000,000
Number of term loan facilities | Facility	3
Unused credit facility expiration date			Sep. 29, 2021
Fixed interest rate on loan amounts outstanding	9.00%
Loan and security agreement, term	48 months
Loan and security agreement, interest only payment period	24 months
Expiration of interest only period	Sep. 29, 2022
Loan and security agreement, number of quarterly payments | Installment	8
Loan and security agreement, frequency of payments			quarterly
Conversion price for borrowings outstanding | $ / shares	$ 4.10
Debt instrument, terms of conversion description			Pontifax, at its option, has the right to convert at any time any portion of the then outstanding borrowings and all accrued but unpaid interest into shares of the Company’s common stock, at the applicable conversion price. The conversion price for borrowings outstanding under the Pontifax Agreement is fixed at $4.10 per share. If the Company consummates a stock split, stock combination, reclassification payment of stock dividend, recapitalization or other similar transaction (each a “Stock Event”), then the applicable conversion price will be proportionately increased or decreased as necessary to reflect the proportionate change in shares of the Company’s common stock issued and outstanding as a result of such Stock Event.
Loan and Security Agreement | Pontifax | Initial Loan
Debt Instrument [Line Items]
Loan agreement, advanced amount	$ 10,000,000
Loan and Security Agreement | Pontifax | Credit Line
Debt Instrument [Line Items]
Loan agreement, remaining borrowing capacity	$ 5,000,000
Loan and security agreement, percentage fee paid	1.00%
Loan and Security Agreement | Pontifax | Third Installment Loan
Debt Instrument [Line Items]
Loan and security agreement, percentage fee paid	1.00%
Loan and security agreement, available borrowing capacity subject to achievement of milestones	$ 10,000,000	$ 10,000,000
Non-contingent, non-refundable gross proceeds from one or more equity financings and/or strategic partnerships	$ 15,000,000	$ 15,000,000

Convertible Debt Agreement - Su

Convertible Debt Agreement - Summary of Minimum Aggregate Future Loan and Interest Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
2021	$ 239
2022	1,927
2023	5,015
2024	4,880
Total minimum payments	12,061
Less: Amount representing interest	(2,061)
Less: Discount	(107)
Loan payable, net of current portion and discount	$ 9,893	$ 9,853

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 12, 2021	Jul. 16, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock, shares issued					80,140,728	50,821,361
Common stock, voting rights					one vote for each share held
Direct Offering
Class of Stock [Line Items]
Number of shares issued and sold		17,416,096
Net proceeds after deducting estimated offering costs		$ 25.4
Maximum aggregate warrant to purchase number of shares of common stock		10,678,872
Warrant to purchase number of share of common stock		0.5
Combined price of each share of common stock and accompanying warrant price per share		$ 1.311
Difference in combined price of each share of common stock and accompanying warrant and purchase price of prefunded warrant per share		$ 0.01
Gross proceeds of the transaction		$ 28
Each warrant exercisable shares		1
Purchase price / Exercise price of warrant		$ 1.25
Warrant exercisable date		Jul. 16, 2026
Direct Offering | Pre-Funded Warrant
Class of Stock [Line Items]
Maximum aggregate warrant to purchase number of shares of common stock		3,941,648
Purchase price of warrant		$ 1.301
Each warrant exercisable shares		1
Purchase price / Exercise price of warrant		$ 0.01
Warrant exercisable date		Jul. 16, 2021
Cowen ATM Agreement
Class of Stock [Line Items]
Number of shares issued and sold				6,058,318
Common stock weighted average price per share				$ 1.99
Net proceeds after deducting estimated offering costs				$ 11.7
B. Riley ATM Agreement | At Market Issuance Sales Agreement
Class of Stock [Line Items]
Number of shares issued and sold			1,650,988
Common stock weighted average price per share			$ 1.25
Net proceeds after deducting estimated offering costs			$ 1.8
B. Riley ATM Agreement | At Market Issuance Sales Agreement | Subsequent Event
Class of Stock [Line Items]
Number of shares issued and sold	2,430,350
Common stock weighted average price per share	$ 1.02
Net proceeds after deducting estimated offering costs	$ 2.4

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shares of Common Stock Reserved (Details) - shares	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	22,204,119	8,144,710
Stock Options and Restricted Stock Units
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	8,744,479	5,359,736
Common Stock Issuable Upon Conversion of Outstanding Debt
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	2,439,024	2,439,024
Employee Stock Purchase Plan
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	332,704	336,910
Warrants
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	10,687,912	9,040

Stock Incentive Plan - Addition

Stock Incentive Plan - Additional Information (Details) - USD ($) $ in Thousands	Jan. 01, 2021	Jan. 01, 2020	Jan. 01, 2019	Oct. 31, 2017	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jan. 22, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock options granted							0		0
Expense related to awards granted						$ 1,035	$ 1,103	$ 2,862	$ 3,136
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation awards, number of shares employees					620,277
Share-based compensation awards, number of shares vested								248,111
Expense related to awards granted						200		$ 600
Share-based payment arrangement, unvested award, unrecognized, amount						$ 100		$ 100
Restricted Stock Units (RSUs) | Vesting on May 10, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation awards, number of shares vested					248,111
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for grant				0
2011 Plan | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, vesting period								4 years
2011 Plan | Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, expiration period								10 years
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option grant effective date				Oct. 31, 2017
Share based award, description								Upon the adoption of the 2017 Plan, no further grants would be made under the 2011 Stock Incentive Plan (“2011 Plan”). The 2017 Plan initially provided for the grant of awards for 2,038,021 shares of common stock. In addition to the shares available for grant under the 2017 Plan, shares underlying any awards outstanding under the 2011 Plan as of the October 31, 2017 that are cancelled, forfeited or otherwise terminated without being exercised will be available for future grant under the 2017 Plan. The 2017 Plan also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 Plan on January 1 of each year. The number of shares added each year will be equal to the lesser of: (i) 4% of the outstanding shares on the immediately preceding December 31 or (ii) such amount as determined by the Compensation Committee of the Board of Directors. On January 1, 2019, 2020 and 2021, the shares available for grant under the 2017 Plan were automatically increased by 832,361, 989,400 and 2,032,854 shares, respectively.
Percentage criteria for additional shares granted				4.00%
Additional shares available for grant	2,032,854	989,400	832,361
2017 Plan | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant						430,856		430,856
Stock-based award, vesting period								4 years
2017 Plan | Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, expiration period								10 years
2017 Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for grant				2,038,021
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant										753,000
2021 Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for grant										1,600,000
2011 and 2017 Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock options granted								3,341,350
Unrecognized stock-based compensation expense related to unvested employee stock options						$ 6,400		$ 6,400
Unrecognized stock-based compensation expense, weighted average period for recognition								2 years 7 months 6 days

Stock Incentive Plan - Summary

Stock Incentive Plan - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,035	$ 1,103	$ 2,862	$ 3,136
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	329	337	879	1,046
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 706	$ 766	$ 1,983	$ 2,090

Stock Incentive Plan - Schedule

Stock Incentive Plan - Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Stock Options (Details) - Stock Options - Employees and Directors	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	0.70%	0.40%
Risk-free interest rate, maximum	1.10%	1.40%
Expected volatility, minimum	92.00%	92.00%
Expected volatility, maximum	95.00%	95.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	7 years	7 years

Stock Incentive Plan - Summar_2

Stock Incentive Plan - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Granted	0		0
2011 and 2017 Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding, Beginning balance		4,110,691
Shares, Granted		3,341,350
Shares, Cancelled		(263,584)
Shares, Outstanding, Ending balance		7,188,457		4,110,691
Shares, Exercisable		3,024,808
Weighted-Average Exercise Price, Outstanding, Beginning balance		$ 3.89
Weighted-Average Exercise Price, Granted		1.87
Weighted-Average Exercise Price, Cancelled		6.92
Weighted-Average Exercise Price, Outstanding, Ending balance		2.84		$ 3.89
Weighted-Average Exercise Price, Exercisable		$ 3.68
Weighted-Average Remaining Contractual Life (in years), Outstanding		7 years 10 months 24 days		7 years 3 months 18 days
Weighted-Average Remaining Contractual Life (in years), Exercisable		6 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding		$ 24		$ 124
Aggregate Intrinsic Value, Exercisable		$ 24

Stock Incentive Plan - Summar_3

Stock Incentive Plan - Summary of Nonvested RSUs (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding, Beginning balance | shares	620,277
Shares, Vested | shares	(248,111)
Shares, Outstanding, Ending balance | shares	372,166
Weighted-Average Grant Date Fair Value, Outstanding, Beginning balance | $ / shares	$ 1.29
Weighted-Average Grant Date Fair Value, Vested | $ / shares	1.29
Weighted-Average Grant Date Fair Value, Outstanding, Ending balance | $ / shares	$ 1.29