Axcella Health (AXLA) 10-Q 12 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Nov. 09, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
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
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		37,540,886
Document Fiscal Year Focus	2020
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, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 114,063	$ 92,053
Marketable securities	3,192	0
Prepaid expenses and other current assets	2,422	1,487
Total current assets	119,677	93,540
Property and equipment, net	265	608
Security deposits	211	211
Total assets	120,153	94,359
Current liabilities:
Accounts payable	1,129	1,998
Accrued expenses and other current liabilities	4,152	6,358
Total current liabilities	5,281	8,356
Long term debt, net of discount	25,115	24,897
Other liabilities	995	882
Total liabilities	31,391	34,135
Commitments and contingencies	0	0
Stockholders' equity:
Common stock, $0.001 par value; 150,000,000 shares authorized, 37,919,824 and 23,607,797 shares issued and 37,500,843 and 23,188,816 shares outstanding at September 30, 2020 and December 31, 2019, respectively	38	24
Additional paid-in capital	346,152	276,286
Treasury stock, 418,981 shares at cost	0	0
Accumulated other comprehensive loss	(4)	0
Accumulated deficit	(257,424)	(216,086)
Total stockholders' equity	88,762	60,224
Total liabilities and stockholders' equity	$ 120,153	$ 94,359

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
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)	37,919,824	23,607,797
Common stock outstanding (in shares)	37,500,843	23,188,816
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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Research and development	$ 7,541	$ 12,157	$ 26,441	$ 29,063
General and administrative	4,184	4,840	12,928	13,036
Total operating expenses	11,725	16,997	39,369	42,099
Loss from operations	(11,725)	(16,997)	(39,369)	(42,099)
Other income (expense):
Change in fair value of preferred stock warrant liability	0	0	0	(51)
Interest income (expense), net	(712)	(307)	(1,969)	(1,174)
Total other income (expense), net	(712)	(307)	(1,969)	(1,225)
Net loss	$ (12,437)	$ (17,304)	$ (41,338)	$ (43,324)
Net loss per basic and diluted (USD per share)	$ (0.34)	$ (0.75)	$ (1.39)	$ (3.01)
Weighted average common shares outstanding, basic and diluted (in shares)	36,942,475	23,083,367	29,804,034	14,430,397
Comprehensive loss:
Net loss	$ (12,437)	$ (17,304)	$ (41,338)	$ (43,324)
Other comprehensive income (loss):
Unrealized losses on marketable securities	(4)	0	(4)	0
Comprehensive loss	$ (12,441)	$ (17,304)	$ (41,342)	$ (43,324)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (41,338)	$ (43,324)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	343	518
Stock-based compensation expense	4,927	4,322
Change in fair value of preferred stock warrant liability	0	51
Non-cash interest expense	354	429
Gain on sale of property and equipment	0	(18)
Changes in current assets and liabilities:
Prepaid expenses and other assets	(935)	(2,108)
Accounts payable	(810)	2,013
Accrued expenses and other current liabilities	(2,249)	536
Net cash used in operating activities	(39,708)	(37,581)
Cash flows from investing activities:
Purchases of property and equipment	(59)	(102)
Proceeds from the sale of property and equipment	0	19
Purchases of marketable securities	(3,196)	0
Net cash used in investing activities	(3,255)	(83)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	64,973	64,532
Payment of success fee obligation	0	(1,220)
Proceeds from exercise of common stock options	0	241
Net cash provided by financing activities	64,973	63,553
Net increase in cash and cash equivalents	22,010	25,889
Cash and cash equivalents, beginning of period	92,053	79,466
Cash and cash equivalents, end of period	114,063	105,355
Supplemental cash flow information:
Cash paid for interest	1,842	2,151
Supplemental disclosure of non-cash investing and financing activities:
Reclassification of warrants to additional paid-in capital	0	476
Conversion of preferred stock to common stock upon closing of the initial public offering	0	197,888
Public offering costs incurred but unpaid at period end	$ 20	$ 0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Treasury stock	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2018		5,193,915		418,981
Beginning balance at Dec. 31, 2018	$ (149,753)	$ 6	$ 7,290	$ 0	$ 0	$ (157,049)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		1,335
Exercise of common stock options	12		12
Accretion of preferred stock to redemption value	(46)		(46)
Stock-based compensation	1,137		1,137
Net loss	(11,573)					(11,573)
Ending balance (in shares) at Mar. 31, 2019		5,195,250		418,981
Ending balance at Mar. 31, 2019	(160,223)	$ 6	8,393	$ 0	0	(168,622)
Beginning balance (in shares) at Dec. 31, 2018		5,193,915		418,981
Beginning balance at Dec. 31, 2018	(149,753)	$ 6	7,290	$ 0	0	(157,049)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of warrants to additional paid-in capital	476
Net loss	(43,324)
Ending balance (in shares) at Sep. 30, 2019		23,517,446		418,981
Ending balance at Sep. 30, 2019	74,344	$ 24	274,693	$ 0	0	(200,373)
Beginning balance (in shares) at Mar. 31, 2019		5,195,250		418,981
Beginning balance at Mar. 31, 2019	(160,223)	$ 6	8,393	$ 0	0	(168,622)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		44,697
Exercise of common stock options	211		211
Conversion of preferred stock to common stock upon closing of the initial public offering (in shares)		14,641,997
Conversion of preferred stock to common stock upon closing of the initial public offering	197,888	$ 15	197,873
Issuance of common stock, net of issuance costs (in shares)		3,571,428
Issuance of common stock, net of issuance costs	64,532	$ 3	64,529
Reclassification of warrants to additional paid-in capital	476		476
Exercise of common stock warrant (in shares)		45,414
Exercise of common stock warrant	0
Stock-based compensation	1,507		1,507
Net loss	(14,447)					(14,447)
Ending balance (in shares) at Jun. 30, 2019		23,498,786		418,981
Ending balance at Jun. 30, 2019	89,944	$ 24	272,989	$ 0	0	(183,069)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		18,660
Exercise of common stock options	26		26
Stock-based compensation	1,678		1,678
Net loss	(17,304)					(17,304)
Ending balance (in shares) at Sep. 30, 2019		23,517,446		418,981
Ending balance at Sep. 30, 2019	74,344	$ 24	274,693	$ 0	0	(200,373)
Beginning balance (in shares) at Dec. 31, 2019		23,607,797		418,981
Beginning balance at Dec. 31, 2019	60,224	$ 24	276,286	$ 0	0	(216,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,599		1,599
Net loss	(15,009)					(15,009)
Ending balance (in shares) at Mar. 31, 2020		23,607,797		418,981
Ending balance at Mar. 31, 2020	46,814	$ 24	277,885	$ 0	0	(231,095)
Beginning balance (in shares) at Dec. 31, 2019		23,607,797		418,981
Beginning balance at Dec. 31, 2019	$ 60,224	$ 24	276,286	$ 0	0	(216,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	4,071
Reclassification of warrants to additional paid-in capital	$ 0
Net loss	(41,338)
Ending balance (in shares) at Sep. 30, 2020		37,919,824		418,981
Ending balance at Sep. 30, 2020	88,762	$ 38	346,152	$ 0	(4)	(257,424)
Beginning balance (in shares) at Mar. 31, 2020		23,607,797		418,981
Beginning balance at Mar. 31, 2020	46,814	$ 24	277,885	$ 0	0	(231,095)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		3,166
Exercise of common stock options	0
Issuance of common stock, net of issuance costs (in shares)		13,055,264
Issuance of common stock, net of issuance costs	58,085	$ 13	58,072
Stock-based compensation	1,956		1,956
Net loss	(13,892)					(13,892)
Ending balance (in shares) at Jun. 30, 2020		36,666,227		418,981
Ending balance at Jun. 30, 2020	92,963	$ 37	337,913	$ 0	0	(244,987)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs (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 loss on available-for-sale securities	(4)				(4)
Net loss	(12,437)					(12,437)
Ending balance (in shares) at Sep. 30, 2020		37,919,824		418,981
Ending balance at Sep. 30, 2020	$ 88,762	$ 38	$ 346,152	$ 0	$ (4)	$ (257,424)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Statement of Stockholders' Equity [Abstract]
Stock issuance costs	$ 230	$ 4,338	$ 6,896

NATURE OF BUSINESS

NATURE OF BUSINESS	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF BUSINESS	NATURE OF BUSINESS Axcella Health Inc. and subsidiaries ("Axcella," the "Company" or "we") 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. 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. The Company has historically funded its operations with proceeds from sales of preferred and common stock and borrowings under a loan and security agreement. As of September 30, 2020, the Company had an accumulated deficit of $257.4 million. The Company expects to continue to generate operating losses in the foreseeable future. The Company expects that its cash and cash equivalents at September 30, 2020 will be sufficient to fund its operations for at least the next twelve months from the date of the issuance of these interim condensed consolidated financial statements. The COVID-19 pandemic has spread globally, including to the United States and European countries, which has resulted in significant governmental measures being implemented to control the spread of the virus, including quarantines, travel restrictions, business shutdowns and clinical site closures to non-essential care and clinical trials. Although we cannot presently predict the scope and severity of COVID-19, these developments and measures could materially and adversely affect our business, our results of operations and financial condition, particularly if the COVID-19 pandemic adversely impacts our ability to conduct and complete our ongoing Clinical Study and planned Clinical Trials in a timely manner or at all. Additionally, potential shutdowns of government agencies such as the Securities and Exchange Commission (the “SEC”) or the U.S. Food and Drug Administration (the "FDA") may limit our ability to raise capital and negatively impact our product development timelines. The Company considered the impact of COVID-19 on the assumptions and estimates used and determined that there were no material adverse impacts on the Company’s results of operations and financial position as of and for the three and nine months ended September 30, 2020. The full extent of the future impacts of COVID-19 on our operations is uncertain. A prolonged pandemic could have a material adverse impact on financial results and business operations of the Company, including the timing and ability of the Company to complete our ongoing Clinical Study and planned Clinical Trials and other efforts required to advance the development of our product candidates.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Principles of Consolidation The Company's condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"). The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Unaudited Interim Financial Information The Company's unaudited condensed consolidated financial statements have been prepared in accordance with GAAP and pursuant to the rules and regulations of the SEC. 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. Accordingly, these condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2019 and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on March 23, 2020 (the "2019 Annual Report"). The results for any interim period are not necessarily indicative of results for any future period. The unaudited condensed 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 condensed consolidated financial statements contain all adjustments that are necessary to present fairly the Company’s financial position, the results of its operations, its statement of stockholders’ equity, and its cash flows for the periods presented. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results for the year ending December 31, 2020, or for any future period. The accompanying unaudited condensed consolidated financial statements reflect the application of certain significant accounting policies as described below and elsewhere in these notes to the unaudited condensed consolidated financial statements. As of September 30, 2020, there have been no material changes in the Company's significant accounting policies from those that were disclosed in the 2019 Annual Report. 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 and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting period. 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. 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 maintains its cash and cash equivalent balances and marketable securities with financial institutions that management believes are creditworthy. The Company’s cash equivalents and marketable securities as of September 30, 2020 consisted of corporate obligations, bank deposits, and money market funds that invest in U.S. treasury securities. 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. Cash Equivalents and Marketable Securities The Company considers all highly liquid investments with a remaining maturity when purchased of three months or less to be cash equivalents. The Company’s marketable securities, which consisted of corporate obligations as of September 30, 2020, are classified as available-for-sale and are reported at fair value. Unrealized gains and losses on available-for-sale corporate obligations 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 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 statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. 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 nine months ended September 30, 2020, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities. 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 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. 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 costs 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 consolidated financial statements.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2020
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 $ 3,511 $ 3,511 Leasehold improvements 597 597 Office and computer equipment 111 111 Furniture and fixtures 122 122 Property and equipment 4,341 4,341 Less: accumulated depreciation and amortization (4,076) (3,733) Property and equipment, net $ 265 $ 608 Depreciation and amortization expense for the nine months ended September 30, 2020 and 2019 was $0.3 million and $0.5 million, respectively.

MARKETABLE SECURITIES AND FAIR

MARKETABLE SECURITIES AND FAIR VALUE	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
MARKETABLE SECURITIES AND FAIR VALUE	MARKETABLE SECURITIES AND FAIR VALUE As of September 30, 2020, marketable securities by security type consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate obligations $ 3,196 $ — $ (4) $ 3,192 Total $ 3,196 $ — $ (4) $ 3,192 The Company did not have marketable securities at December 31, 2019. 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 of the valuation techniques the Company utilized to determine such fair value, which is described further within Note 2, Summary of Significant Accounting Policies (in thousands): Fair value measurements at September 30, 2020 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 111,565 $ — $ — $ 111,565 Marketable securities: Corporate obligations — 3,192 — 3,192 Total $ 111,565 $ 3,192 $ — $ 114,757 Fair value measurements at December 31, 2019 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents $ 91,803 $ — $ — $ 91,803 Total $ 91,803 $ — $ — $ 91,803

ACCRUED EXPENSES AND OTHER CURR

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES	9 Months Ended
	Sep. 30, 2020
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 $ 2,525 $ 3,109 Accrued external research and development expenses 772 1,799 Accrued professional fees 797 985 Other 58 465 Total accrued expenses and other current liabilities $ 4,152 $ 6,358

DEBT FINANCING

DEBT FINANCING	9 Months Ended
	Sep. 30, 2020
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 (351) (456) Deferred financing fees (534) (647) Long term debt, net $ 25,115 $ 24,897 In January 2018, the Company entered into a Loan and Security Agreement. Under the Loan and Security Agreement, t he Company granted the lender a first priority security interest in all assets of the Company, excluding intellectual property and granted a negative pledge on such intellectual property. The interest rate was LIBOR plus 8.50% per annum. In October 2018, the Company amended its Loan and Security Agreement to extend the interest only period through January 2021 and the maturity date to January 2023 if certain conditions were met. The conditions per the agreement were met upon the completion of the IPO in May 2019. Additionally, per the amended agreement, the monthly principal payments of $1.1 million were to commence in February 2021 for 24 months. The interest rate was not changed through the amendment. On August 28, 2020, the Loan and Security Agreement was further amended to, among other things; (i) extend the date on which repayment of principal commences until November 2021, (ii) provide for further extensions of the date on which repayment of principal commences to January 2022 and May 2022, provided that certain specified regulatory and clinical milestones are satisfied by the Company, (iii) increase the final payment fee from 5.35% to 6.35% and (iv) add a 0.20% floor to the LIBOR rate. The interest rate was 8.70% as of September 30, 2020 . For the nine months ended September 30, 2020 and 2019, interest expense arising from the amortization of the debt discount and deferred financing fees was $0.3 million and $0.4 million, respectively. Terminal Interest Fee The Company's debt facility includes a terminal interest fee obligation totaling $1.7 million, which is due with the final principal payment of the loan and has been modified from time to time as the facilities were amended. The Company is accruing the terminal fee obligation over the term of the facility. The carrying value of the terminal interest fee was $1.0 million and $0.9 million at September 30, 2020 and December 31, 2019, respectively. The scheduled principal maturity of the long term debt as of September 30, 2020 is as follows (in thousands): Year Ending December 31, 2021 $ 2,167 2022 13,000 2023 10,833 $ 26,000

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Redeemable Convertible Preferred Stock Upon closing of the IPO, all outstanding redeemable convertible preferred stock converted into an aggregate of 14,641,997 shares of common stock. The holders of the Company’s preferred stock had certain voting, dividend, and redemption rights, as well as liquidation preferences and conversion privileges. All rights, preferences, and privileges associated with the preferred stock were terminated at the time of the Company’s IPO in conjunction with the conversion of all outstanding shares of preferred stock into shares of common stock. 2020 Follow-on Offering On May 18, 2020, the Company completed a public offering pursuant to which the Company issued an aggregate of 12,650,000 shares of its common stock, which included the full exercise of the underwriters’ option to purchase additional shares, at a public offering price of $4.75 per share, before deducting underwriting discounts and commissions. The Company received net proceeds of approximately $55.9 million after deducting the underwriting discounts, commissions, and other offering expenses. At-the-Market Offering On June 5, 2020, the Company entered into a sales agreement with SVB Leerink LLC (“SVB Leerink”) pursuant to which the Company may offer and sell shares of its common stock having an aggregate offering price of up to $35 million from time to time through SVB Leerink, acting as its agent (the “ATM Offering”). During the three and nine months ended September 30, 2020, the Company sold an aggregate of 1,253,597 and 1,658,861 shares, respectively, of its common stock under the ATM Offering for net cash proceeds of $6.9 million and $9.0 million, respectively, after deducting commissions and expenses of $0.2 million and $0.4 million, respectively. 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 grant under the 2019 Plan was 747,299 as of September 30, 2020. 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. As of September 30, 2020, the total number of shares that may be issued under the 2019 ESPP was 469,069 shares. As of September 30, 2020, no shares have been issued under the 2019 ESPP. Fair Value of Stock Awards 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 2020 2019 2020 2019 Risk-free interest rate 0.38 % 1.43% - 1.95% 1.12 % 1.43% - 2.50% Expected option life (in years) 6.06 0.34 - 6.25 5.93 0.25 - 6.25 Expected dividend yield 0 % 0 % 0 % 0 % Expected volatility 75.5 % 73.4 % 73.6 % 73.4 % Stock Option Activity The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2020: Number of Shares Weighted Weighted Intrinsic Outstanding as of January 1, 2020 5,176,944 $ 7.35 Granted 801,890 4.44 Exercised (4,071) 1.12 Canceled (812,963) 8.93 Outstanding as of September 30, 2020 5,161,800 $ 6.65 7.52 $ 1,772 Exercisable as of September 30, 2020 2,835,131 $ 6.98 6.71 $ 1,151 Vested or expected to vest as of September 30, 2020 5,136,800 $ 6.65 7.52 $ 1,772 The intrinsic value of options exercised was nominal during both the nine months ended September 30, 2020 and 2019. The weighted-average grant date fair value of the options granted during the nine months ended September 30, 2020 and 2019, was $2.83 and $6.73 per share, respectively. 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, 2020: Number of Shares Weighted Average Grant Date Fair Value per Share Outstanding as of January 1, 2020 66,801 $ 3.40 Granted 336,166 4.61 Vested — — Forfeited (108,371) 3.68 Outstanding as of September 30, 2020 294,596 $ 4.67 Stock-Based Compensation Expense Stock-based compensation expense was classified in the statements of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Research and development $ 532 $ 659 $ 2,129 $ 1,727 General and administrative 840 1,019 2,798 2,595 Total stock compensation expense $ 1,372 $ 1,678 $ 4,927 $ 4,322

NET LOSS PER SHARE

NET LOSS PER SHARE	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE Net Loss Per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Numerator: Net loss $ (12,437) $ (17,304) $ (41,338) $ (43,324) Accretion of redeemable convertible preferred stock — — — (46) Net loss attributable to common stockholders $ (12,437) $ (17,304) $ (41,338) $ (43,370) Denominator: Weighted average common shares outstanding, basic and diluted 36,942,475 23,083,367 29,804,034 14,430,397 Net loss per share, basic and diluted $ (0.34) $ (0.75) $ (1.39) $ (3.01) 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 2020 2019 Options to purchase common stock 5,161,800 4,895,872 Unvested restricted stock units 294,596 — 5,456,396 4,895,872

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2020
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. The total expense under the agreement for the three and nine months ended September 30, 2020 was $0.1 million and $0.2 million, respectively. As of September 30, 2020, there were no amounts payable to the chairman for costs related to the consulting agreement.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSThe Company has evaluated subsequent events for financial statement purposes occurring through November 12, 2020, the date that these condensed consolidated financial statements were issued.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Principles of Consolidation The Company's condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP").
Principles of Consolidation	The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
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 and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting period. 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.
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 maintains its cash and cash equivalent balances and marketable securities with financial institutions that management believes are creditworthy. The Company’s cash equivalents and marketable securities as of September 30, 2020 consisted of corporate obligations, bank deposits, and money market funds that invest in U.S. treasury securities.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities The Company considers all highly liquid investments with a remaining maturity when purchased of three months or less to be cash equivalents. The Company’s marketable securities, which consisted of corporate obligations as of September 30, 2020, are classified as available-for-sale and are reported at fair value. Unrealized gains and losses on available-for-sale corporate obligations 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 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 statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. 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 nine months ended September 30, 2020, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities.
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 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. 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 costs 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 consolidated financial statements.

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2020
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 $ 3,511 $ 3,511 Leasehold improvements 597 597 Office and computer equipment 111 111 Furniture and fixtures 122 122 Property and equipment 4,341 4,341 Less: accumulated depreciation and amortization (4,076) (3,733) Property and equipment, net $ 265 $ 608

MARKETABLE SECURITIES AND FAI_2

MARKETABLE SECURITIES AND FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Marketable Securities	As of September 30, 2020, marketable securities by security type consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate obligations $ 3,196 $ — $ (4) $ 3,192 Total $ 3,196 $ — $ (4) $ 3,192
Schedule of Fair Value Hierarchy of Assets and Liabilities	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 of the valuation techniques the Company utilized to determine such fair value, which is described further within Note 2, Summary of Significant Accounting Policies (in thousands): Fair value measurements at September 30, 2020 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 111,565 $ — $ — $ 111,565 Marketable securities: Corporate obligations — 3,192 — 3,192 Total $ 111,565 $ 3,192 $ — $ 114,757 Fair value measurements at December 31, 2019 using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents $ 91,803 $ — $ — $ 91,803 Total $ 91,803 $ — $ — $ 91,803

ACCRUED EXPENSES AND OTHER CU_2

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES Payables and Accruals (Tables)	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): ​ September 30, December 31, Accrued employee compensation and benefits $ 2,525 $ 3,109 Accrued external research and development expenses 772 1,799 Accrued professional fees 797 985 Other 58 465 Total accrued expenses and other current liabilities $ 4,152 $ 6,358

DEBT FINANCING (Tables)

DEBT FINANCING (Tables)	9 Months Ended
	Sep. 30, 2020
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 (351) (456) Deferred financing fees (534) (647) Long term debt, net $ 25,115 $ 24,897
Schedule of Maturities of Long-term Debt	The scheduled principal maturity of the long term debt as of September 30, 2020 is as follows (in thousands): Year Ending December 31, 2021 $ 2,167 2022 13,000 2023 10,833 $ 26,000

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Summary 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 2020 2019 2020 2019 Risk-free interest rate 0.38 % 1.43% - 1.95% 1.12 % 1.43% - 2.50% Expected option life (in years) 6.06 0.34 - 6.25 5.93 0.25 - 6.25 Expected dividend yield 0 % 0 % 0 % 0 % Expected volatility 75.5 % 73.4 % 73.6 % 73.4 %
Summary of Options Plan	The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2020: Number of Shares Weighted Weighted Intrinsic Outstanding as of January 1, 2020 5,176,944 $ 7.35 Granted 801,890 4.44 Exercised (4,071) 1.12 Canceled (812,963) 8.93 Outstanding as of September 30, 2020 5,161,800 $ 6.65 7.52 $ 1,772 Exercisable as of September 30, 2020 2,835,131 $ 6.98 6.71 $ 1,151 Vested or expected to vest as of September 30, 2020 5,136,800 $ 6.65 7.52 $ 1,772
Share-based Payment Arrangement, Restricted Stock Unit, Activity	The following table summarizes the Company's restricted stock unit activity for the nine months ended September 30, 2020: Number of Shares Weighted Average Grant Date Fair Value per Share Outstanding as of January 1, 2020 66,801 $ 3.40 Granted 336,166 4.61 Vested — — Forfeited (108,371) 3.68 Outstanding as of September 30, 2020 294,596 $ 4.67
Summary of Stock Based Compensation Expense	Stock-based compensation expense was classified in the statements of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Research and development $ 532 $ 659 $ 2,129 $ 1,727 General and administrative 840 1,019 2,798 2,595 Total stock compensation expense $ 1,372 $ 1,678 $ 4,927 $ 4,322

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Numerator: Net loss $ (12,437) $ (17,304) $ (41,338) $ (43,324) Accretion of redeemable convertible preferred stock — — — (46) Net loss attributable to common stockholders $ (12,437) $ (17,304) $ (41,338) $ (43,370) Denominator: Weighted average common shares outstanding, basic and diluted 36,942,475 23,083,367 29,804,034 14,430,397 Net loss per share, basic and diluted $ (0.34) $ (0.75) $ (1.39) $ (3.01)
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 2020 2019 Options to purchase common stock 5,161,800 4,895,872 Unvested restricted stock units 294,596 — 5,456,396 4,895,872

NATURE OF BUSINESS (Details)

NATURE OF BUSINESS (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ (257,424)	$ (216,086)

PROPERTY AND EQUIPMENT - Summar

PROPERTY AND EQUIPMENT - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment	$ 4,341	$ 4,341
Less: accumulated depreciation and amortization	(4,076)	(3,733)
Property and equipment, net	265	608
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment	3,511	3,511
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	597	597
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	111	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, 2020	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 343	$ 518

MARKETABLE SECURITIES AND FAI_3

MARKETABLE SECURITIES AND FAIR VALUE (Details) $ in Thousands	Sep. 30, 2020USD ($)
Marketable Securities [Line Items]
Amortized Cost	$ 3,196
Gross Unrealized Gains	0
Gross Unrealized Losses	(4)
Estimated Fair Value	3,192
Corporate obligations
Marketable Securities [Line Items]
Amortized Cost	3,196
Gross Unrealized Gains	0
Gross Unrealized Losses	(4)
Estimated Fair Value	$ 3,192

MARKETABLE SECURITIES AND FAI_4

MARKETABLE SECURITIES AND FAIR VALUE - Narrative (Details)	Dec. 31, 2019USD ($)
Fair Value Disclosures [Abstract]
Marketable securities	$ 0

MARKETABLE SECURITIES AND FAI_5

MARKETABLE SECURITIES AND FAIR VALUE - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Estimated Fair Value	$ 3,192
Corporate obligations
Assets:
Estimated Fair Value	3,192
Fair Value, Recurring
Assets:
Cash and cash equivalents	111,565	$ 91,803
Total	114,757	91,803
Fair Value, Recurring | Level 1
Assets:
Cash and cash equivalents	111,565	91,803
Total	111,565	91,803
Fair Value, Recurring | Level 2
Assets:
Cash and cash equivalents	0	0
Total	3,192	0
Fair Value, Recurring | Level 3
Assets:
Cash and cash equivalents	0	0
Total	0	$ 0
Fair Value, Recurring | Corporate obligations
Assets:
Estimated Fair Value	3,192
Fair Value, Recurring | Corporate obligations | Level 1
Assets:
Estimated Fair Value	0
Fair Value, Recurring | Corporate obligations | Level 2
Assets:
Estimated Fair Value	3,192
Fair Value, Recurring | Corporate obligations | Level 3
Assets:
Estimated Fair Value	$ 0

ACCRUED EXPENSES AND OTHER CU_3

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 2,525	$ 3,109
Accrued external research and development expenses	772	1,799
Accrued professional fees	797	985
Other	58	465
Total accrued expenses and other current liabilities	$ 4,152	$ 6,358

DEBT FINANCING - Summary of Lon

DEBT FINANCING - Summary of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Principal amount of long term debt	$ 26,000	$ 26,000
Debt discount	(351)	(456)
Deferred financing fees	(534)	(647)
Long term debt, net	$ 25,115	$ 24,897

DEBT FINANCING - Narrative (Det

DEBT FINANCING - Narrative (Details) - USD ($) $ in Millions	Aug. 28, 2020	Feb. 28, 2021	Jan. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Oct. 31, 2018
Line of Credit Facility [Line Items]
Interest expense				$ 0.3	$ 0.4
2018 Facility | LIBOR | Secured Debt
Line of Credit Facility [Line Items]
Basis spread on interest rate			8.50%
Amended 2018 Facility | Secured Debt
Line of Credit Facility [Line Items]
Increase in final payment fee percent	5.35%
Final payment fee percent	6.35%
Amended 2018 Facility | Line of Credit
Line of Credit Facility [Line Items]
Terminal fee							$ 1.7
Terminal fee, at carrying value				$ 1		$ 0.9
Amended 2018 Facility | LIBOR | Secured Debt
Line of Credit Facility [Line Items]
Basis spread on interest rate floor				0.20%
Interest rate during period				8.70%
Forecast | Amended 2018 Facility | Line of Credit
Line of Credit Facility [Line Items]
Monthly principal payments		$ 1.1
Term		24 months

DEBT FINANCING - Maturities of

DEBT FINANCING - Maturities of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2021	$ 2,167
2022	13,000
2023	10,833
Principal amount of long-term debt	$ 26,000	$ 26,000

STOCKHOLDERS' EQUITY - Redeemab

STOCKHOLDERS' EQUITY - Redeemable Convertible Preferred Stock, IPO, Public Offering and ATM Offering Narrative (Details) - USD ($)	Jun. 05, 2020	May 18, 2020	May 13, 2019	Sep. 30, 2020	Sep. 30, 2020
Subsidiary, Sale of Stock [Line Items]
Payments of stock issuance costs				$ 200,000	$ 400,000
IPO
Subsidiary, Sale of Stock [Line Items]
Shares converted (in shares)			14,641,997
2020 Follow-on Offering
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)		12,650,000
Shares sold, par value (USD per share)		$ 4.75
Net proceeds on offering		$ 55,900,000
At-the-Market Offering
Subsidiary, Sale of Stock [Line Items]
Shares sold (in shares)				1,253,597	1,658,861
Net proceeds on offering				$ 6,900,000	$ 9,000,000
At-the-Market Offering | Maximum
Subsidiary, Sale of Stock [Line Items]
Net proceeds on offering	$ 35,000,000

STOCKHOLDERS' EQUITY - 2019 Sto

STOCKHOLDERS' EQUITY - 2019 Stock Option, Incentive Plan and Employee Stock Purchase Plan Narrative (Details)	Sep. 30, 2020shares
2019 Stock Plan | Options to purchase common stock | Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	747,299
Employee Stock Purchase Plan 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance (in shares)	469,069

STOCKHOLDERS' EQUITY - Stock Op

STOCKHOLDERS' EQUITY - Stock Option Valuation Fair Value Measurement Inputs (Details) - Stock options	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.38%		1.12%
Risk-free interest rate, minimum		1.43%		1.43%
Risk-free interest rate, maximum		1.95%		2.50%
Expected option life (in years)	6 years 21 days		5 years 11 months 4 days
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	75.50%	73.40%	73.60%	73.40%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life (in years)		4 months 2 days		3 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life (in years)		6 years 3 months		6 years 3 months

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity and Restricted Stock Units (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares
Number of Shares
Outstanding, beginning balance (in shares) | shares	5,176,944
Granted (in shares) | shares	801,890
Exercised (in shares) | shares	(4,071)
Canceled (in shares) | shares	(812,963)
Outstanding, ending balance (in shares) | shares	5,161,800
Options exercisable (in shares) | shares	2,835,131
Options vested or expected to vest (in shares) | shares	5,136,800
Weighted Average Exercise Price
Weighted average exercise price, outstanding, beginning balance (USD per share) | $ / shares	$ 7.35
Weighted-average exercise price, granted (USD per share) | $ / shares	4.44
Weighted-average exercise price, exercised (USD per share) | $ / shares	1.12
Weighted-average exercise price, canceled (USD per share) | $ / shares	8.93
Weighted average exercise price, outstanding, ending balance (USD per share) | $ / shares	6.65
Weighted-average exercise price, options exercisable (USD per share) | $ / shares	6.98
Weighted-average exercise price, options vested or expected to vest (USD per share) | $ / shares	$ 6.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Life, Outstanding (in Years)	7 years 6 months 7 days
Weighted Average Remaining Life, Options exercisable (in Years)	6 years 8 months 15 days
Weighted Average Remaining Life, Options vested or expected to vest (in Years)	7 years 6 months 7 days
Intrinsic Value, Outstanding | $	$ 1,772
Intrinsic Value, Options exercisable | $	1,151
Intrinsic Value, Options vested or expected to vest | $	$ 1,772
RSUs
Number of Shares
Outstanding, beginning balance (in shares) | shares	66,801
Granted (in shares) | shares	336,166
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(108,371)
Outstanding, ending balance (in shares) | shares	294,596
Weighted Average Grant Date Fair Value per Share
Weighted average exercise price, outstanding, beginning balance (USD per share) | $ / shares	$ 3.40
Weighted-average exercise price, granted (USD per share) | $ / shares	4.61
Weighted-average exercise price, vested (USD per share) | $ / shares	0
Weighted-average exercise price, forfeited (USD per share) | $ / shares	3.68
Weighted average exercise price, outstanding, ending balance (USD per share) | $ / shares	$ 4.67

STOCKHOLDERS' EQUITY - Summar_2

STOCKHOLDERS' EQUITY - Summary of Stock Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,372	$ 1,678	$ 4,927	$ 4,322
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	532	659	2,129	1,727
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 840	$ 1,019	$ 2,798	$ 2,595

STOCKHOLDERS' EQUITY - Stock _2

STOCKHOLDERS' EQUITY - Stock Option Activity and Stock-based Compensation Expense Narrative (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value, options exercised	$ 0	$ 0
Weighted-average grand date fair value of options granted in the period (USD per share)	$ 2.83	$ 6.73
Unrecognized compensation expense related to unvested stock options	$ 8,300,000
Unrecognized compensation expense, recognition period	2 years 1 month 6 days
Unvested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested stock options	$ 800,000
Unrecognized compensation expense, recognition period	1 year 9 months 18 days

NET LOSS PER SHARE - Calculatio

NET LOSS PER SHARE - Calculation of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (12,437)	$ (13,892)	$ (15,009)	$ (17,304)	$ (14,447)	$ (11,573)	$ (41,338)	$ (43,324)
Accretion of redeemable convertible preferred stock	0			0			0	(46)
Net loss attributable to common stockholders	$ (12,437)			$ (17,304)			$ (41,338)	$ (43,370)
Denominator:
Weighted average common shares outstanding, basic and diluted (in shares)	36,942,475			23,083,367			29,804,034	14,430,397
Net loss per basic and diluted (USD per share)	$ (0.34)			$ (0.75)			$ (1.39)	$ (3.01)

NET LOSS PER SHARE - Summary of

NET LOSS PER SHARE - Summary of Anti-dilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	5,456,396	4,895,872
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	5,161,800	4,895,872
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	294,596	0

RELATED-PARTY TRANSACTIONS - Na

RELATED-PARTY TRANSACTIONS - Narrative (Details) - Board of Directors Chairman	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Related Party Services Agreement
Related Party Transaction [Line Items]
Related party costs	$ 100,000	$ 200,000
Related Party Consulting Agreement
Related Party Transaction [Line Items]
Due to related parties	$ 0	$ 0