Axcella Health (AXLA) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 05, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-38501
Entity Registrant Name	AXCELLA HEALTH INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3321056
Entity Address, Address Line One	840 Memorial Drive
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	857
Local Phone Number	320-2200
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	AXLA
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		38,916,570
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0001633070
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 26,091	$ 71,590
Marketable securities	40,055	35,739
Prepaid expenses and other current assets	1,521	1,692
Total current assets	67,667	109,021
Property and equipment, net	943	360
Other assets	211	211
Total assets	68,821	109,592
Current liabilities:
Accounts payable	2,985	2,290
Accrued expenses and other current liabilities	4,772	5,494
Total current liabilities	7,757	7,784
Long-term debt, net of discount	25,021	25,222
Other liabilities	482	1,205
Total liabilities	33,260	34,211
Commitments and contingencies (Note 10)	0	0
Stockholders' equity:
Common stock, $0.001 par value; 150,000,000 shares authorized, 38,688,955 and 38,022,273 shares issued and 38,269,974 and 37,603,292 shares outstanding at September 30, 2021 and December 31, 2020, respectively	39	38
Additional paid-in capital	354,879	347,990
Treasury stock, 418,981 shares at cost	0	0
Accumulated other comprehensive loss	(7)	(34)
Accumulated deficit	(319,350)	(272,613)
Total stockholders' equity	35,561	75,381
Total liabilities and stockholders' equity	$ 68,821	$ 109,592

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	150,000,000	150,000,000
Common stock issued (in shares)	38,688,955	38,022,273
Common stock outstanding (in shares)	38,269,974	37,603,292
Treasury stock at cost (in shares)	418,981	418,981

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	$ 10,130	$ 7,541	$ 30,668	$ 26,441
General and administrative	4,773	4,184	13,975	12,928
Total operating expenses	14,903	11,725	44,643	39,369
Loss from operations	(14,903)	(11,725)	(44,643)	(39,369)
Other income (expense):
Interest income	32	6	115	281
Interest expense	(742)	(713)	(2,204)	(2,243)
Other income (expense), net	0	(5)	(5)	(7)
Total other income (expense), net	(710)	(712)	(2,094)	(1,969)
Net loss	$ (15,613)	$ (12,437)	$ (46,737)	$ (41,338)
Net loss per share, basic (USD per share)	$ (0.41)	$ (0.34)	$ (1.23)	$ (1.39)
Net loss per share, diluted (USD per share)	$ (0.41)	$ (0.34)	$ (1.23)	$ (1.39)
Weighted average common shares outstanding, basic (in shares)	38,195,583	36,942,475	37,861,970	29,804,034
Weighted average common shares outstanding, diluted (in shares)	38,195,583	36,942,475	37,861,970	29,804,034
Comprehensive loss:
Net loss	$ (15,613)	$ (12,437)	$ (46,737)	$ (41,338)
Other comprehensive income (loss):
Unrealized gains (losses) on marketable securities	2	(4)	27	(4)
Comprehensive loss	$ (15,611)	$ (12,441)	$ (46,710)	$ (41,342)

Condensed Consolidated Statem_2

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	$ (46,737)	$ (41,338)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	213	343
Stock-based compensation	4,772	4,927
Non-cash interest expense	477	354
Other non-cash items	619	0
Changes in current assets and liabilities:
Prepaid expenses and other current assets	171	(935)
Accounts payable	736	(810)
Accrued expenses and other current liabilities	(835)	(2,249)
Net cash used in operating activities	(40,584)	(39,708)
Cash flows from investing activities:
Purchases of property and equipment	(275)	(59)
Purchases of marketable securities	(23,234)	(3,196)
Proceeds from maturities of marketable securities	18,326	0
Net cash used in investing activities	(5,183)	(3,255)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	1,920	64,973
Proceeds from exercise of common stock options and ESPP	163	0
Payments for capital lease	(89)	0
Payment of terminal fee obligation and debt issuance costs	(1,726)	0
Net cash provided by financing activities	268	64,973
Net (decrease) increase in cash and cash equivalents	(45,499)	22,010
Cash and cash equivalents, beginning of period	71,590	92,053
Cash and cash equivalents, end of period	26,091	114,063
Supplemental cash flow information:
Cash paid for interest	1,727	1,842
Supplemental disclosure of non-cash investing and financing activities:
Offering costs incurred but unpaid at period end	0	20
Property and equipment acquired via capital lease	$ 534	$ 0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at beginning of period (in shares) at Dec. 31, 2019		23,607,797
Balance at beginning of period at Dec. 31, 2019	$ 60,224	$ 24	$ 276,286	$ 0	$ (216,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,599		1,599
Net loss	(15,009)				(15,009)
Balance at end of period (in shares) at Mar. 31, 2020		23,607,797
Balance at end of period at Mar. 31, 2020	46,814	$ 24	277,885	0	(231,095)
Balance at beginning of period (in shares) at Dec. 31, 2019		23,607,797
Balance at beginning of period at Dec. 31, 2019	60,224	$ 24	276,286	0	(216,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(41,338)
Balance at end of period (in shares) at Sep. 30, 2020		37,919,824
Balance at end of period at Sep. 30, 2020	88,762	$ 38	346,152	(4)	(257,424)
Balance at beginning of period (in shares) at Mar. 31, 2020		23,607,797
Balance at beginning of period at Mar. 31, 2020	46,814	$ 24	277,885	0	(231,095)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		13,055,264
Issuance of common stock, net of issuance costs	58,085	$ 13	58,072
Exercise of common stock options (in shares)		3,166
Stock-based compensation	1,956		1,956
Net loss	(13,892)				(13,892)
Balance at end of period (in shares) at Jun. 30, 2020		36,666,227
Balance at end of period at Jun. 30, 2020	92,963	$ 37	337,913	0	(244,987)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		1,253,597
Issuance of common stock, net of issuance costs	6,868	$ 1	6,867
Stock-based compensation	1,372		1,372
Unrealized gain (loss) on marketable securities	(4)			(4)
Net loss	(12,437)				(12,437)
Balance at end of period (in shares) at Sep. 30, 2020		37,919,824
Balance at end of period at Sep. 30, 2020	88,762	$ 38	346,152	(4)	(257,424)
Balance at beginning of period (in shares) at Dec. 31, 2020		38,022,273
Balance at beginning of period at Dec. 31, 2020	75,381	$ 38	347,990	(34)	(272,613)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Costs incurred for the issuance of common stock	4		4
Exercise of common stock options (in shares)		27,143
Exercise of common stock options	27		27
Vesting of restricted stock units (in shares)		60,000
Stock-based compensation	1,428		1,428
Unrealized gain (loss) on marketable securities	7			7
Net loss	(15,189)				(15,189)
Balance at end of period (in shares) at Mar. 31, 2021		38,109,416
Balance at end of period at Mar. 31, 2021	61,658	$ 38	349,449	(27)	(287,802)
Balance at beginning of period (in shares) at Dec. 31, 2020		38,022,273
Balance at beginning of period at Dec. 31, 2020	$ 75,381	$ 38	347,990	(34)	(272,613)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	111,833
Net loss	$ (46,737)
Balance at end of period (in shares) at Sep. 30, 2021		38,688,955
Balance at end of period at Sep. 30, 2021	35,561	$ 39	354,879	(7)	(319,350)
Balance at beginning of period (in shares) at Mar. 31, 2021		38,109,416
Balance at beginning of period at Mar. 31, 2021	61,658	$ 38	349,449	(27)	(287,802)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		126,527
Issuance of common stock, net of issuance costs	556	$ 1	555
Exercise of common stock options (in shares)		3,257
Exercise of common stock options	6		6
Vesting of restricted stock units (in shares)		4,604
Issuance of common stock related to ESPP (in shares)		30,465
Issuance of common stock related to ESPP	107		107
Stock-based compensation	1,677		1,677
Unrealized gain (loss) on marketable securities	18			18
Net loss	(15,935)				(15,935)
Balance at end of period (in shares) at Jun. 30, 2021		38,274,269
Balance at end of period at Jun. 30, 2021	48,087	$ 39	351,794	(9)	(303,737)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		321,149
Issuance of common stock, net of issuance costs	1,395		1,395
Exercise of common stock options (in shares)		81,433
Exercise of common stock options	23		23
Vesting of restricted stock units (in shares)		12,104
Stock-based compensation	1,667		1,667
Unrealized gain (loss) on marketable securities	2			2
Net loss	(15,613)				(15,613)
Balance at end of period (in shares) at Sep. 30, 2021		38,688,955
Balance at end of period at Sep. 30, 2021	$ 35,561	$ 39	$ 354,879	$ (7)	$ (319,350)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020
Statement of Stockholders' Equity [Abstract]
Stock issuance cost	$ 56	$ 71	$ 230	$ 4,338

NATURE OF BUSINESS

NATURE OF BUSINESS	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF BUSINESS	NATURE OF BUSINESS Company Overview Axcella Health Inc., doing business as “Axcella Therapeutics,” and subsidiaries ("Axcella," the "Company," "we" or "us") is a biotechnology company that was incorporated in Delaware on August 27, 2008 and has a principal place of business in Cambridge, Massachusetts. The Company is focused on pioneering a new approach to treat complex diseases and improve health using endogenous metabolic modulator, or EMM, compositions. The Company's product candidates are comprised of multiple EMMs that are engineered in distinct combinations and ratios with the goal of simultaneously impacting multiple biological pathways. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, successful development of technology, obtaining additional funding, protection of proprietary technology, compliance with government regulations, risks of failure of preclinical studies, Clinical Studies and Clinical Trials, the need to obtain marketing approval for its product candidates, if required, and successfully market products, fluctuations in operating results, economic pressure impacting therapeutic pricing, dependence on key personnel, risks associated with changes in technologies, development by competitors of technological innovations and the ability to scale manufacturing to large scale production. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and any necessary regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Going Concern The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Consequently, management has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within 12 months after the date the quarterly financial statements herein are issued. Historically, the Company has funded its operations with proceeds from sales of preferred and common stock and borrowings under a loan and security agreement. The Company has spent, and expects to continue to spend, significant funds in connection with implementing its business strategy, including its continued development of AXA1665, AXA1125, and future pipeline candidates. Furthermore, the Company may never commercialize a product and achieve profitability, and unless and until it does, the Company will need to raise additional capital. As of September 30, 2021, the Company had cash, cash equivalents and marketable securities of $66.1 million, and an accumulated deficit of $319.4 million. Management believes that it will require additional working capital to fund its planned operations through a full 12 months from the issuance date of this Quarterly Report on Form 10-Q. These factors individually and collectively raise substantial doubt about the Company’s ability to continue as a going concern. Additional funding will be necessary beyond this point to continue to fund the Company’s research and development activities. Management’s plans to alleviate its financing requirements include pursuing one or more of the following steps, among others, none of which can be guaranteed or are entirely within the Company’s control: • The sale of the Company’s common stock • Funding received from the establishment of a collaboration(s) with a potential partner(s) to further advance the Company’s product pipeline If the Company is unable to alleviate its financing requirements via these means, it could be forced to discontinue some of its operations or develop and implement a plan to further extend payables, reduce overhead or scale back its current operating plan until sufficient additional capital is raised to support further operations. The accompanying unaudited condensed consolidated financial statements do not include any adjustments or classifications that may result from the possible inability of the Company to continue as a going concern.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“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 Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Furthermore, the accompanying condensed consolidated financial statements are unaudited and certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. As of September 30, 2021, the Company’s significant accounting policies and estimates, which are detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, have not changed, and the unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements as of and for the year ended December 31, 2020. The accompanying interim condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of 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 2020, its cash flows for the nine months ended September 30, 2021 and 2020, and its statements of stockholders’ equity for the three and nine months ended September 30, 2021 and 2020. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020, and the notes thereto, together with Management’s Discussion and Analysis of Financial Condition and Results of Operations, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of Axcella Health Inc. and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the CEO, who is the chief operating decision maker, in making decisions on how to allocate resources and assess performance. The Company operates in one reportable business segment. Use of Estimates The preparation of the condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, expenses and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the Company’s ability to continue as a going concern. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions. Cash and Cash Equivalents Cash and cash equivalents include cash held in banks and amounts held in interest-bearing money market accounts. Cash equivalents are carried at cost, which approximates their fair market value. The Company considers all highly liquid investments with a remaining maturity when purchased of three months or less to also be cash equivalents. Marketable Securities The Company’s marketable securities, which consisted of corporate debt obligations as of September 30, 2021, are classified as available-for-sale and are reported at fair value. Unrealized gains and losses on available-for-sale securities are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses and declines in value determined to be other than temporary are based on the specific identification method and are included as a component of other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the condensed consolidated statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Concentrations of Credit Risk The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company’s cash equivalents and marketable securities as of September 30, 2021 consisted of bank deposits, money market funds that invest in U.S. treasury securities, and corporate obligations. We invest in high-quality financial instruments and our portfolio does not consist of any instrument with a maturity duration in excess of twenty-four months, which we believe limits our credit risk. In addition, the Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines the allowable investments that the Company believes minimizes the exposure to concentrations of credit risk. The Company has not experienced any credit losses and does not believe that it is subject to significant credit risk. Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1 — Quoted prices in active markets for identical assets or liabilities. • Level 2 — Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3 — Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and marketable securities are carried at fair value, determined according to the fair value hierarchy described above. The carrying values of the Company’s accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities. The carrying value of the long-term debt approximates fair value as evidenced by the recent amendment to the Company's debt facility. Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the three and nine months ended September 30, 2021, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities. Net Loss Per Share Basic net loss per share attributable to common stockholders is calculated by dividing net loss by the weighted average shares outstanding during the period. Diluted net income (loss) per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period. All common stock equivalents have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Accounting Pronouncements Issued and Not Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), as amended by various subsequently issued ASUs. The standard requires lessees to recognize an operating lease with a term greater than one year on their balance sheets as a right-of-use asset and corresponding lease liability, measured at the present value of the lease payments. The new standard will become effective for the Company on January 1, 2022. The Company expects to apply the modified retrospective approach as of the date of adoption such that prior periods will not be restated. The Company is evaluating the effect that adoption of the standard is expected to have on the Company’s condensed consolidated financial statements and related disclosures and will recognize a lease obligation and right of use asset for its existing operating leases with a lease term greater than one year upon adoption. The Company anticipates that the adoption of ASU 2016-02 will have a material impact on the Company’s financial position and the related footnote disclosures. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) . The new standard adjusts the accounting for assets held at amortized cost basis, including marketable securities accounted for as available-for-sale. The standard eliminates the probable initial recognition threshold and requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. The Company is required to adopt this standard effective January 1, 2023 and the Company is evaluating the impact the guidance will have on its condensed consolidated financial statements.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The following tables present the Company’s assets that are measured at fair value on a recurring basis and indicate the level within the fair value hierarchy (in thousands): Fair Value Measurements at September 30, 2021 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 24,446 $ — $ — $ 24,446 Marketable securities: Corporate obligations — 40,055 — 40,055 Total $ 24,446 $ 40,055 $ — $ 64,501 Fair Value Measurements at December 31, 2020 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 69,118 $ — $ — $ 69,118 Marketable securities: Corporate obligations — 35,739 — 35,739 Total $ 69,118 $ 35,739 $ — $ 104,857

CASH, CASH EQUIVALENTS, AND MAR

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES	CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES As of September 30, 2021, and December 31, 2020, cash, cash equivalents and marketable securities by security type consisted of the following (in thousands): September 30, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Cash and cash equivalents $ 26,091 $ — $ — $ 26,091 Corporate obligations 40,062 8 (15) 40,055 Total $ 66,153 $ 8 $ (15) $ 66,146 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Cash and cash equivalents $ 71,590 $ — $ — $ 71,590 Corporate obligations 35,773 1 (35) 35,739 Total $ 107,363 $ 1 $ (35) $ 107,329 The fair values of cash equivalents and marketable securities by contractual maturity were as follows (in thousands): Contractual Maturities September 30, December 31, Mature in one year or less $ 54,374 $ 86,338 Mature in two years or less 10,127 18,519 Total $ 64,501 $ 104,857 Marketable securities with maturities beyond one year are classified as short-term marketable securities in the condensed consolidated balance sheets due to their highly liquid nature and because they represent the Company’s investments that are available for current operations. All cash equivalents mature within three months or less. Operating cash of $1.6 million and $2.5 million is excluded from the above table as of September 30, 2021 and December 31, 2020, respectively. There were no sales of our marketable securities during the three and nine months ended September 30, 2021 and September 30, 2020, respectively.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 3,426 $ 3,022 Leasehold improvements 564 564 Office and computer equipment 146 111 Furniture and fixtures 122 122 Property and equipment 4,258 3,819 Less: accumulated depreciation and amortization (3,315) (3,459) Property and equipment, net $ 943 $ 360

ACCRUED EXPENSES AND OTHER CURR

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES	ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, Accrued employee compensation and benefits $ 2,145 $ 2,998 Accrued external research and development expenses 1,762 1,870 Accrued professional fees 613 626 Other 252 — Total accrued expenses and other current liabilities $ 4,772 $ 5,494

DEBT FINANCING

DEBT FINANCING	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
DEBT FINANCING	DEBT FINANCING Long-term debt consisted of the following (in thousands): September 30, December 31, Principal amount of long-term debt $ 26,000 $ 26,000 Debt discount (206) (308) Deferred financing fees (773) (470) Long-term debt, net of discount $ 25,021 $ 25,222 On September 2, 2021, the Company entered into a loan and security agreement (the "New Loan and Security Agreement") with SLR Investment Corp., formerly known as Solar Capital Ltd., for term loans in an aggregate principal amount of $26.0 million. The New Loan and Security Agreement replaced the loan and security agreement between the Company and SLR Investment Corp., dated as of January 9, 2018 and further amended on October 5, 2018, November 30, 2018 and August 28, 2020 (as amended, the "Prior Loan and Security Agreement"). The New Loan and Security agreement will be accounted for as a debt modification or exchange as the Company determined that the terms of the New Loan and Security Agreement were not substantially different than the terms of the Prior Loan and Security Agreement. Upon entering into the New Loan and Security Agreement, the Company paid a terminal fee obligation and debt issuance costs totaling $1.7 million as required under the terms of the Prior Loan and Security Agreement, of which $1.3 million had been accrued as of September 2, 2021. The Company will defer and amortize $0.4 million of the $1.7 million paid to interest expense along with the unamortized deferred financing fees balance as of September 2, 2021 over the term of the New Loan Security Agreement. The remaining unamortized debt discount balance as of September 2, 2021 will also be amortized to interest expense over the term of the New Loan and Security Agreement. The Company also agreed to a new terminal fee obligation totaling $1.7 million, which is due and payable on the earliest to occur of (i) the maturity of the New Loan and Security Agreement, (ii) the acceleration of the term loans, and (iii) the prepayment, refinancing, substitution or replacement of the term loans. The obligation is equal to 6.45% of the aggregate principal amount of $26.0 million. The Company is accruing the obligation over the term of the New Loan and Security Agreement. The carrying value of the obligation was nominal as of September 30, 2021. The term loans under the New Loan and Security Agreement will accrue interest at an annual rate equal to 8.60% plus the greater of (a) the thirty (30) day U.S. Dollar LIBOR rate and (b) 0.10%, payable monthly in arrears. The interest rate was 8.70% as of September 30, 2021 . The monthly principal payments of $0.6 million will be paid over a period of 45 months beginning in January 2023 through the final maturity date of September 1, 2026. Per the New Loan and Security Agreement, the date on which repayment of principal commences can be further extended to July 2023 and January 2024, provided we satisfy certain equity related conditions. The term loans are also subject to a prepayment fee of 3.00% if prepayment occurs within the first year subsequent to September 2, 2021 , 2.00% in the second year and 1.00% in the third year through final maturity. The New Loan and Security Agreement also contains certain financial covenants, including an unrestricted minimum cash level until certain clinical trial study data conditions are met. Customary representations and warranties, as well as certain non-financial covenants, including engaging in any change of control transaction or incurring additional indebtedness or liens are included in the New Loan and Security Agreement as well. As security for its obligations under the New Loan and Security Agreement, the Company granted the SLR Investment Corp. a first priority perfected security interest in all of the Company’s existing and after-acquired assets, including intellectual property. The scheduled principal maturity of the long-term debt as of September 30, 2021 is as follows (in thousands): Year Ending December 31, 2021 (remaining 3 months) $ — 2022 — 2023 6,933 2024 6,933 2025 6,934 Thereafter 5,200 $ 26,000

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY 2019 Stock Option and Incentive Plan The 2019 Stock Option and Incentive Plan (the "2019 Plan") provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards and cash-based awards to the Company's officers, employees, directors and consultants. The number of shares available for future issuance under the 2019 Plan was 1,143,830 shares as of September 30, 2021. 2019 Employee Stock Purchase Plan The 2019 Employee Stock Purchase Plan (the "2019 ESPP") provides participating employees with the opportunity to purchase shares of common stock. The number of shares available for future issuance under the 2019 ESPP was 635,742 shares as of September 30, 2021. The Company recorded $0.1 million of stock-based compensation expense for the nine months ended September 30, 2021. The stock-based compensation expense recorded during the same period in 2020 was nominal. Stock-Based Compensation Expense In connection with all share-based payment awards, total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Research and development $ 455 $ 532 $ 1,305 $ 2,129 General and administrative 1,212 840 3,467 2,798 Total stock-based compensation expense $ 1,667 $ 1,372 $ 4,772 $ 4,927 Fair Value of Stock Options The fair value of each option issued to employees was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Risk-free interest rate 1.08 % 0.38 % 0.84 % 1.12 % Expected option life (in years) 6.08 6.06 6.00 5.93 Expected dividend yield — % — % — % — % Expected volatility 93.1 % 75.5 % 96.8 % 73.6 % Stock Option Activity The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2021: Number of Shares Weighted Weighted Intrinsic Outstanding as of January 1, 2021 4,919,960 $ 6.37 Granted 2,303,601 5.57 Exercised (111,833) 0.50 Canceled (1,081,682) 7.54 Outstanding as of September 30, 2021 6,030,046 $ 5.97 7.61 $ 341 Exercisable as of September 30, 2021 3,167,833 $ 6.35 6.39 $ 341 Vested or expected to vest as of September 30, 2021 5,980,046 $ 5.93 7.54 $ 341 The intrinsic value of options exercised during the nine months ended September 30, 2021 was $0.4 million. The intrinsic value of options exercised during the same period in 2020 was nominal. The weighted-average grant date fair value of the options granted during the nine months ended September 30, 2021 and 2020 was $4.25 and $2.83 per share, respectively. As of September 30, 2021, there was $9.9 million of unrecognized compensation expense that is expected to be recognized over a weighted-average period of approximately 2.69 years. Restricted Stock Units The fair values of restricted stock units are based on the market value of our stock on the date of grant. The following table summarizes the Company's restricted stock unit activity for the nine months ended September 30, 2021: Number of Shares Weighted Average Outstanding as of January 1, 2021 347,587 $ 4.04 Granted 120,916 6.41 Vested (76,708) 5.04 Forfeited (46,386) 4.42 Outstanding as of September 30, 2021 345,409 $ 4.60

NET LOSS PER SHARE

NET LOSS PER SHARE	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended 2021 2020 Options to purchase common stock 6,030,046 5,161,800 Unvested restricted stock units 345,409 294,596 Shares issuable under employee stock purchase plan 24,770 — 6,400,225 5,456,396

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Other Commitments We enter into contracts in the normal course of business with contract research organizations ("CROs"), contract manufacturing organizations ("CMOs") and other third parties for preclinical research studies, Clinical Studies, Clinical Trials and testing and manufacturing services. These contracts do not contain minimum purchase commitments and are cancelable upon prior written notice. Payments due upon cancellation consist only of payments for services provided or expenses incurred, including non-cancelable obligations of service providers, up to the date of cancellation. Legal Proceedings

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	RELATED-PARTY TRANSACTIONSIn August 2019, the Company entered into a consulting agreement with the chairman of the Company's Board of Directors to provide various consulting services to the Company in exchange for cash and equity compensation. In March 2021, the consulting agreement was modified so that the chairman would no longer receive cash compensation for his consulting services and would instead be compensated solely via equity compensation. The aggregate grant date fair value of the equity awarded to the chairman in 2021 and 2020 for his consulting services was $0.6 million and $0.2 million, respectively. The grant date fair value is calculated in accordance with FASB ASC Topic 718. The total cash paid under the agreement was $0.1 million for the nine months ended September 30, 2021. No cash was paid under the agreement for the three months ended September 30, 2021.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSThe Company has evaluated subsequent events for financial statement purposes occurring through the date these condensed consolidated financial statements were issued and determined that there are no material recognized or unrecognized subsequent events requiring disclosure.

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 condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“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 Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Furthermore, the accompanying condensed consolidated financial statements are unaudited and certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. As of September 30, 2021, the Company’s significant accounting policies and estimates, which are detailed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, have not changed, and the unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements as of and for the year ended December 31, 2020. The accompanying interim condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of 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 2020, its cash flows for the nine months ended September 30, 2021 and 2020, and its statements of stockholders’ equity for the three and nine months ended September 30, 2021 and 2020. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020, and the notes thereto, together with Management’s Discussion and Analysis of Financial Condition and Results of Operations, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of Axcella Health Inc. and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Segment Information	Segment InformationOperating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the CEO, who is the chief operating decision maker, in making decisions on how to allocate resources and assess performance. The Company operates in one reportable business segment.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, expenses and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the Company’s ability to continue as a going concern. The Company bases its estimates on historical experience, known trends and other market-specific or relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include cash held in banks and amounts held in interest-bearing money market accounts. Cash equivalents are carried at cost, which approximates their fair market value. The Company considers all highly liquid investments with a remaining maturity when purchased of three months or less to also be cash equivalents.
Marketable Securities	Marketable Securities The Company’s marketable securities, which consisted of corporate debt obligations as of September 30, 2021, are classified as available-for-sale and are reported at fair value. Unrealized gains and losses on available-for-sale securities are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses and declines in value determined to be other than temporary are based on the specific identification method and are included as a component of other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the condensed consolidated statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Concentrations of Credit Risk	Concentrations of Credit Risk The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company’s cash equivalents and marketable securities as of September 30, 2021 consisted of bank deposits, money market funds that invest in U.S. treasury securities, and corporate obligations. We invest in high-quality financial instruments and our portfolio does not consist of any instrument with a maturity duration in excess of twenty-four months, which we believe limits our credit risk. In addition, the Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines the allowable investments that the Company believes minimizes the exposure to concentrations of credit risk. The Company has not experienced any credit losses and does not believe that it is subject to significant credit risk.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1 — Quoted prices in active markets for identical assets or liabilities. • Level 2 — Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3 — Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents and marketable securities are carried at fair value, determined according to the fair value hierarchy described above. The carrying values of the Company’s accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities. The carrying value of the long-term debt approximates fair value as evidenced by the recent amendment to the Company's debt facility.
Comprehensive Loss	Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the three and nine months ended September 30, 2021, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities.
Net Loss Per Share	Net Loss Per ShareBasic net loss per share attributable to common stockholders is calculated by dividing net loss by the weighted average shares outstanding during the period. Diluted net income (loss) per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period. All common stock equivalents have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented.
Accounting Pronouncements Issued and Not Adopted	Accounting Pronouncements Issued and Not Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), as amended by various subsequently issued ASUs. The standard requires lessees to recognize an operating lease with a term greater than one year on their balance sheets as a right-of-use asset and corresponding lease liability, measured at the present value of the lease payments. The new standard will become effective for the Company on January 1, 2022. The Company expects to apply the modified retrospective approach as of the date of adoption such that prior periods will not be restated. The Company is evaluating the effect that adoption of the standard is expected to have on the Company’s condensed consolidated financial statements and related disclosures and will recognize a lease obligation and right of use asset for its existing operating leases with a lease term greater than one year upon adoption. The Company anticipates that the adoption of ASU 2016-02 will have a material impact on the Company’s financial position and the related footnote disclosures. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) . The new standard adjusts the accounting for assets held at amortized cost basis, including marketable securities accounted for as available-for-sale. The standard eliminates the probable initial recognition threshold and requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. The Company is required to adopt this standard effective January 1, 2023 and the Company is evaluating the impact the guidance will have on its condensed consolidated financial statements.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value	The following tables present the Company’s assets that are measured at fair value on a recurring basis and indicate the level within the fair value hierarchy (in thousands): Fair Value Measurements at September 30, 2021 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 24,446 $ — $ — $ 24,446 Marketable securities: Corporate obligations — 40,055 — 40,055 Total $ 24,446 $ 40,055 $ — $ 64,501 Fair Value Measurements at December 31, 2020 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 69,118 $ — $ — $ 69,118 Marketable securities: Corporate obligations — 35,739 — 35,739 Total $ 69,118 $ 35,739 $ — $ 104,857

CASH, CASH EQUIVALENTS, AND M_2

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Schedule of Cash, Cash Equivalents, and Marketable Securities by Security Type	As of September 30, 2021, and December 31, 2020, cash, cash equivalents and marketable securities by security type consisted of the following (in thousands): September 30, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Cash and cash equivalents $ 26,091 $ — $ — $ 26,091 Corporate obligations 40,062 8 (15) 40,055 Total $ 66,153 $ 8 $ (15) $ 66,146 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Cash and cash equivalents $ 71,590 $ — $ — $ 71,590 Corporate obligations 35,773 1 (35) 35,739 Total $ 107,363 $ 1 $ (35) $ 107,329
Schedule of Fair Values of Cash Equivalents and Marketable Securities by Contractual Maturities	The fair values of cash equivalents and marketable securities by contractual maturity were as follows (in thousands): Contractual Maturities September 30, December 31, Mature in one year or less $ 54,374 $ 86,338 Mature in two years or less 10,127 18,519 Total $ 64,501 $ 104,857

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 3,426 $ 3,022 Leasehold improvements 564 564 Office and computer equipment 146 111 Furniture and fixtures 122 122 Property and equipment 4,258 3,819 Less: accumulated depreciation and amortization (3,315) (3,459) Property and equipment, net $ 943 $ 360

ACCRUED EXPENSES AND OTHER CU_2

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, Accrued employee compensation and benefits $ 2,145 $ 2,998 Accrued external research and development expenses 1,762 1,870 Accrued professional fees 613 626 Other 252 — Total accrued expenses and other current liabilities $ 4,772 $ 5,494

DEBT FINANCING (Tables)

DEBT FINANCING (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Summary of Long-term Debt	Long-term debt consisted of the following (in thousands): September 30, December 31, Principal amount of long-term debt $ 26,000 $ 26,000 Debt discount (206) (308) Deferred financing fees (773) (470) Long-term debt, net of discount $ 25,021 $ 25,222
Schedule of Principal Maturities of Long-term Debt	The scheduled principal maturity of the long-term debt as of September 30, 2021 is as follows (in thousands): Year Ending December 31, 2021 (remaining 3 months) $ — 2022 — 2023 6,933 2024 6,933 2025 6,934 Thereafter 5,200 $ 26,000

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Schedule of Stock-based Compensation Expense Recognized	In connection with all share-based payment awards, total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Research and development $ 455 $ 532 $ 1,305 $ 2,129 General and administrative 1,212 840 3,467 2,798 Total stock-based compensation expense $ 1,667 $ 1,372 $ 4,772 $ 4,927
Schedule of Fair Value Assumptions for Stock Options	The fair value of each option issued to employees was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Risk-free interest rate 1.08 % 0.38 % 0.84 % 1.12 % Expected option life (in years) 6.08 6.06 6.00 5.93 Expected dividend yield — % — % — % — % Expected volatility 93.1 % 75.5 % 96.8 % 73.6 %
Schedule of Stock Option Activity	The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2021: Number of Shares Weighted Weighted Intrinsic Outstanding as of January 1, 2021 4,919,960 $ 6.37 Granted 2,303,601 5.57 Exercised (111,833) 0.50 Canceled (1,081,682) 7.54 Outstanding as of September 30, 2021 6,030,046 $ 5.97 7.61 $ 341 Exercisable as of September 30, 2021 3,167,833 $ 6.35 6.39 $ 341 Vested or expected to vest as of September 30, 2021 5,980,046 $ 5.93 7.54 $ 341
Schedule of Restricted Stock Unit Activity	The following table summarizes the Company's restricted stock unit activity for the nine months ended September 30, 2021: Number of Shares Weighted Average Outstanding as of January 1, 2021 347,587 $ 4.04 Granted 120,916 6.41 Vested (76,708) 5.04 Forfeited (46,386) 4.42 Outstanding as of September 30, 2021 345,409 $ 4.60

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended 2021 2020 Options to purchase common stock 6,030,046 5,161,800 Unvested restricted stock units 345,409 294,596 Shares issuable under employee stock purchase plan 24,770 — 6,400,225 5,456,396

NATURE OF BUSINESS (Details)

NATURE OF BUSINESS (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash, cash equivalents, and marketable securities	$ 66,100
Accumulated deficit	$ (319,350)	$ (272,613)

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	9 Months Ended
	Sep. 30, 2021segment
Accounting Policies [Abstract]
Number of operating segments	1

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets, Fair Value Disclosure [Abstract]
Corporate obligations	$ 66,146	$ 107,329
Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Money market funds	24,446	69,118
Corporate obligations	40,055	35,739
Total	64,501	104,857
Fair Value, Recurring | Level 1
Assets, Fair Value Disclosure [Abstract]
Money market funds	24,446	69,118
Corporate obligations	0	0
Total	24,446	69,118
Fair Value, Recurring | Level 2
Assets, Fair Value Disclosure [Abstract]
Money market funds	0	0
Corporate obligations	40,055	35,739
Total	40,055	35,739
Fair Value, Recurring | Level 3
Assets, Fair Value Disclosure [Abstract]
Money market funds	0	0
Corporate obligations	0	0
Total	$ 0	$ 0

CASH, CASH EQUIVALENTS, AND M_3

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES - Schedule of Securities by Type (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Line Items]
Amortized Cost	$ 26,091	$ 71,590
Corporate obligations	66,153	107,363
Gross Unrealized Gains	8	1
Gross Unrealized Losses	(15)	(35)
Estimated Fair Value	66,146	107,329
Corporate obligations
Cash and Cash Equivalents [Line Items]
Corporate obligations	40,062	35,773
Gross Unrealized Gains	8	1
Gross Unrealized Losses	(15)	(35)
Cash and cash equivalents	26,091	71,590
Estimated Fair Value	$ 40,055	$ 35,739

CASH, CASH EQUIVALENTS, AND M_4

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES - Schedule of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Mature in one year or less	$ 54,374	$ 86,338
Mature in two years or less	10,127	18,519
Total	$ 64,501	$ 104,857

CASH, CASH EQUIVALENTS, AND M_5

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Operating cash	$ 1,600,000		$ 1,600,000		$ 2,500,000
Sales of marketable securities	$ 0	$ 0	$ 0	$ 0

PROPERTY AND EQUIPMENT - Summar

PROPERTY AND EQUIPMENT - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment	$ 4,258	$ 3,819
Less: accumulated depreciation and amortization	(3,315)	(3,459)
Property and equipment, net	943	360
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment	3,426	3,022
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	564	564
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	146	111
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	$ 122	$ 122

PROPERTY AND EQUIPMENT - Narrat

PROPERTY AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 213	$ 343
Property and equipment disposed of	$ 300	$ 0

ACCRUED EXPENSES AND OTHER CU_3

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 2,145	$ 2,998
Accrued external research and development expenses	1,762	1,870
Accrued professional fees	613	626
Other	252	0
Total accrued expenses and other current liabilities	$ 4,772	$ 5,494

DEBT FINANCING - Summary of Lon

DEBT FINANCING - Summary of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Principal amount of long-term debt	$ 26,000	$ 26,000
Debt discount	(206)	(308)
Deferred financing fees	(773)	(470)
Long-term debt, net of discount	$ 25,021	$ 25,222

DEBT FINANCING - Narrative (Det

DEBT FINANCING - Narrative (Details) $ in Thousands	Jan. 01, 2023USD ($)	Sep. 02, 2021USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Line of Credit Facility [Line Items]
Principal amount of long-term debt			$ 26,000		$ 26,000
Debt issuance cost and terminal fee			1,726	$ 0
Accrued issuance cost and terminal interest fee			$ 773		$ 470
New Loan and Security Agreement | Line of Credit
Line of Credit Facility [Line Items]
Principal amount of long-term debt		$ 26,000
Debt issuance cost and terminal fee		1,700
Accrued issuance cost and terminal interest fee		1,300
Unamortized debt issuance cost and terminal fee		400
Terminal fee		$ 1,700
Terminal fee, percent of principal		0.0645
Basis spread on interest rate		8.60%
Interest rate floor, on which basis spread is added		0.10%
New Loan and Security Agreement | Line of Credit | Debt Instrument, Redemption, Period One
Line of Credit Facility [Line Items]
Prepayment fee, percent of principal			0.0300
New Loan and Security Agreement | Line of Credit | Debt Instrument, Redemption, Period Two
Line of Credit Facility [Line Items]
Prepayment fee, percent of principal			0.0200
New Loan and Security Agreement | Line of Credit | Debt Instrument, Redemption, Period Three
Line of Credit Facility [Line Items]
Prepayment fee, percent of principal			0.0100
New Loan and Security Agreement | LIBOR | Line of Credit
Line of Credit Facility [Line Items]
Interest rate at end of period			8.70%
Forecast | New Loan and Security Agreement | Line of Credit
Line of Credit Facility [Line Items]
Principal periodic payments	$ 600
Period of payment	45 months

DEBT FINANCING - Maturities of

DEBT FINANCING - Maturities of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
2021 (remaining 3 months)	$ 0
2022	0
2023	6,933
2024	6,933
2025	6,934
Thereafter	5,200
Principal amount of long-term debt	$ 26,000	$ 26,000

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (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
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,667	$ 1,372	$ 4,772	$ 4,927
Intrinsic value, options exercised			$ 400
Weighted-average grand date fair value of options granted in the period (USD per share)			$ 4.25	$ 2.83
Unrecognized compensation expense related to unvested stock options	9,900		$ 9,900
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, recognition period			2 years 8 months 8 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, recognition period			1 year 10 months 17 days
Unrecognized compensation expense related to unvested stock RSUs	$ 900		$ 900
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	635,742		635,742
Stock-based compensation expense			$ 100
Stock Option And Incentive Plan 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	1,143,830		1,143,830

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Stock 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 Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,667	$ 1,372	$ 4,772	$ 4,927
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	455	532	1,305	2,129
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,212	$ 840	$ 3,467	$ 2,798

STOCKHOLDERS' EQUITY - Stock Op

STOCKHOLDERS' EQUITY - Stock Option Valuation Fair Value Measurement Inputs (Details) - Stock options	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]
Risk-free interest rate	1.08%	0.38%	0.84%	1.12%
Expected option life (in years)	6 years 29 days	6 years 21 days	6 years	5 years 11 months 4 days
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	93.10%	75.50%	96.80%	73.60%

STOCKHOLDERS' EQUITY - Summar_2

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021
Number of Shares
Number of shares outstanding at beginning of period (in shares)	4,919,960
Shares granted (in shares)	2,303,601
Shares exercised (in shares)	(111,833)
Shares canceled (in shares)	(1,081,682)
Number of shares outstanding at end of period (in shares)	6,030,046
Shares exercisable (in shares)	3,167,833
Shares vested or expected to vest (in shares)	5,980,046
Weighted Average Exercise Price
Weighted average exercise price of shares outstanding at beginning of period (USD per share)	$ 6.37
Weighted-average exercise price of shares granted (USD per share)	5.57
Weighted-average exercise price of shares exercised (USD per share)	0.50
Weighted-average exercise price of shares canceled (USD per share)	7.54
Weighted average exercise price of shares outstanding at end of period (USD per share)	5.97
Weighted-average exercise price of shares exercisable (USD per share)	6.35
Weighted-average exercise price of shares vested or expected to vest (USD per share)	$ 5.93
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining life of shares outstanding (in years)	7 years 7 months 9 days
Weighted average remaining life of shares exercisable (in years)	6 years 4 months 20 days
Weighted average remaining life of shares vested or expected to vest (in years)	7 years 6 months 14 days
Intrinsic value of shares outstanding	$ 341
Intrinsic value of shares exercisable	341
Intrinsic value of shares vested or expected to vest	$ 341

STOCKHOLDERS' EQUITY - Summar_3

STOCKHOLDERS' EQUITY - Summary of Restricted Stock Units (Details) - RSUs	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of Shares
RSUs outstanding at beginning of period (in shares) | shares	347,587
RSUs granted (in shares) | shares	120,916
RSUs vested (in shares) | shares	(76,708)
RSUs forfeited (in shares) | shares	(46,386)
RSUs outstanding at end of period (in shares) | shares	345,409
Weighted Average Grant Date Fair Value per Share
Weighted average exercise price of RSUs outstanding at beginning of period (USD per share) | $ / shares	$ 4.04
Weighted-average exercise price of RSUs granted (USD per share) | $ / shares	6.41
Weighted-average exercise price of RSUs vested (USD per share) | $ / shares	5.04
Weighted-average exercise price of RSUs forfeited (USD per share) | $ / shares	4.42
Weighted average exercise price of RSUs outstanding at end of period (USD per share) | $ / shares	$ 4.60

NET LOSS PER SHARE (Details)

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]
Antidilutive securities excluded from computation of diluted net loss per share (in shares)	6,400,225	5,456,396
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share (in shares)	6,030,046	5,161,800
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share (in shares)	345,409	294,596
Shares issuable under employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share (in shares)	24,770	0

RELATED-PARTY TRANSACTIONS (Det

RELATED-PARTY TRANSACTIONS (Details) - Related Party Consulting Agreement - Board of Directors Chairman - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Grant date fair value of equity awarded		$ 0.6	$ 0.2
Related party costs	$ 0	$ 0.1