0001633070-21-000009 | 10-K | XBRL Viewer

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Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2020	Mar. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 106,565,992
Entity Common Stock, Shares Outstanding (in shares)		37,690,435
Documents Incorporated by Reference	Part III of this Annual Report on Form 10-K incorporates by reference certain information from the registrant’s definitive proxy statement for its 2021 annual meeting of shareholders, or the Proxy Statement, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of December 31, 2020. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Central Index Key	0001633070

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 71,590	$ 92,053
Marketable securities	35,739	0
Prepaid expenses and other current assets	1,692	1,487
Total current assets	109,021	93,540
Property and equipment, net	360	608
Other assets	211	211
Total assets	109,592	94,359
Current liabilities:
Accounts payable	2,290	1,998
Accrued expenses and other current liabilities	5,494	6,358
Total current liabilities	7,784	8,356
Long-term debt, net of discount	25,222	24,897
Other liabilities	1,205	882
Total liabilities	34,211	34,135
Commitments and contingencies (Note 11)	0	0
Stockholders' equity:
Common stock, $0.001 par value; 150,000,000 shares authorized, 38,022,273 and 23,607,797 shares issued and 37,603,292 and 23,188,816 shares outstanding at December 31, 2020 and 2019, respectively	38	24
Additional paid-in capital	347,990	276,286
Treasury stock, 418,981 shares at cost	0	0
Accumulated other comprehensive loss	(34)	0
Accumulated deficit	(272,613)	(216,086)
Total stockholders' equity	75,381	60,224
Total liabilities and stockholders' equity	$ 109,592	$ 94,359

Consolidated Balance Sheet (Parenthetical) - $ / shares	Dec. 31, 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)	38,022,273	23,607,797
Common stock outstanding (in shares)	37,603,292	23,188,816
Treasury stock at cost (in shares)	418,981	418,981

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 37,039	$ 41,658
General and administrative	16,797	15,781
Total operating expenses	53,836	57,439
Loss from operations	(53,836)	(57,439)
Interest Income, Nonoperating	306	1,814
Other income (expense):
Interest expense	(3,007)	(3,395)
Total other income (expense), net	10	(17)
Nonoperating Income (Expense)	(2,691)	(1,598)
Net loss	$ (56,527)	$ (59,037)
Net loss per share, basic and diluted (USD per share)	$ (1.78)	$ (3.55)
Weighted average common shares outstanding, basic and diluted (in shares)	31,747,676	16,624,941
Comprehensive loss:
Net loss	$ (56,527)	$ (59,037)
Other comprehensive income (loss):
Unrealized losses on marketable securities	(34)	0
Comprehensive loss	$ (56,561)	$ (59,037)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (56,527)	$ (59,037)
Adjustment to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	419	662
Stock-based compensation	6,287	5,824
Change in fair value of preferred stock warrant liability	0	51
Non-cash interest expense	580	557
Other non-cash items	128	(18)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(205)	(652)
Other long-term assets	0	5
Accounts payable	311	366
Accrued expenses and other current liabilities	(764)	1,280
Net cash used in operating activities	(49,771)	(50,962)
Cash flows from investing activities:
Purchases of property and equipment	(239)	(136)
Proceeds from the sale of property and equipment	40	19
Purchases of marketable securities	(35,920)	0
Net cash used in investing activities	(36,119)	(117)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	65,322	64,546
Payment of debt issuance costs	(39)	0
Payment of success fee obligation	0	(1,220)
Proceeds from exercise of common stock options and ESPP	144	340
Net cash provided by financing activities	65,427	63,666
Net (decrease) increase in cash and cash equivalents	(20,463)	12,587
Cash and cash equivalents, beginning of year	92,053	79,466
Cash and cash equivalents, end of year	71,590	92,053
Supplemental cash flow information:
Cash paid for interest	2,420	2,838
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
Accretion of preferred stock to redemption value	0	46
Purchases of property and equipment included in accounts payable	13	59
Public offering costs incurred but unpaid at period end	$ 35	$ 0

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2018		5,193,915
Beginning balance at Dec. 31, 2018	$ (149,753)	$ 6	$ 7,290	$ 0	$ (157,049)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		155,043
Exercise of common stock options	340		340
Accretion of preferred stock to redemption value	(46)		(46)
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 (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	5,824		5,824
Net loss	(59,037)				(59,037)
Ending balance (in shares) at Dec. 31, 2019		23,607,797
Ending balance at Dec. 31, 2019	$ 60,224	$ 24	276,286	0	(216,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	4,071	3,166
Exercise of common stock options	$ 0
Issuance of common stock, net (in shares)		14,371,267
Issuance of common stock, net of issuance costs	65,287	$ 14	65,273
Reclassification of warrants to additional paid-in capital	0
Issuance of common stock related to ESPP (in shares)		40,043
Issuance of common stock related to ESPP	144		144
Stock-based compensation	6,287		6,287
Unrealized loss on marketable securities	(34)			(34)
Net loss	(56,527)				(56,527)
Ending balance (in shares) at Dec. 31, 2020		38,022,273
Ending balance at Dec. 31, 2020	$ 75,381	$ 38	$ 347,990	$ (34)	$ (272,613)

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Stock issuance costs	$ 4,599	$ 6,896

NATURE OF BUSINESS	12 Months Ended
NATURE OF BUSINESS	Dec. 31, 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 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 December 31, 2020, the Company had an accumulated deficit of $272.6 million. The Company expects to continue to generate operating losses for the foreseeable future. The Company believes the cash, cash equivalents, and marketable securities on hand as of December 31, 2020 of $107.3 million will be sufficient to fund its operations for at least the next 12 months following the issuance date of these consolidated financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying 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”).

Principles of Consolidation

The accompanying 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 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 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.

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 December 31, 2020, 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 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.

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 December 31, 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.

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.

Property and Equipment

Property and equipment are recorded at cost. Depreciation and amortization is calculated using the straight-line method over the following estimated useful lives of the assets:


			Estimated useful life
Computer equipment and software			3 years
Office equipment			3 - 5 years
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of the asset’s estimated useful life or the remaining lease term

Upon disposal, retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred.

Impairment of Long-Lived Assets

Long-lived assets consist of property and equipment. The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. There were no significant impairments of long‑lived assets for the years ended December 31, 2020 or 2019.

Research and Development Costs

Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities, Clinical Studies and Clinical Trials as well as to manufacture research and development materials. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and are recognized as an expense as the goods are consumed or the related services are performed.

The Company has entered into various research and development related contracts. The Company records accrued liabilities for research costs incurred but not paid. When measuring the accrued liabilities, the Company analyzes progress of the Clinical Studies or Clinical Trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.

Stock-Based Compensation

The Company measures the estimated fair value of the stock-based award on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the award. For stock-based awards with service-based vesting conditions, the Company records the expense for these awards using the straight-line method. For stock options with performance-based vesting conditions, the Company records the expense for these awards over the requisite service period using an accelerated attribution method to the extent the achievement of the performance condition is probable. The Company accounts for forfeitures as they occur.

The Company classifies stock-based compensation expense in the consolidated statements of operations in the same manner in which the award recipient’s cash compensation costs are classified.

Income Taxes

Deferred tax assets and liabilities are recognized for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on the difference between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided to reduce the deferred tax asset to an amount, which, more likely than not, will be realized.

The Company recognizes the tax benefit from any uncertain tax positions only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. Interest and penalties associated with uncertain tax positions are recorded as a component of income tax expense. As of December 31, 2020 and 2019, the Company has not identified any uncertain tax positions for which reserves would be required.

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 year ended December 31, 2020, 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.

Recently Adopted Accounting Pronouncements

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.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

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 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


	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

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

12 Months Ended

Dec. 31, 2020

Cash and Cash Equivalents [Abstract]

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

As of December 31, 2020 and 2019, cash, cash equivalents, and marketable securities by security type consisted of the following (in thousands):


	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


	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value




Cash and cash equivalents	$	92,053	$	—	$	—	$	92,053
Corporate obligations	—		—		—		—
Total	$	92,053	$	—	$	—	$	92,053

The fair values of cash equivalents and marketable securities by contractual maturity were as follows (in thousands):


	December 31,
Contractual maturities	2020		2019
Mature in one year or less	$	86,338	$	91,803
Mature in two years or less	18,519		—
Total	$	104,857	$	91,803

Marketable securities with maturities beyond one year are classified as short-term marketable securities in the 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 $2.5 million and $0.3 million is excluded from the above table as of December 31, 2020 and 2019, respectively.

PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

Property and equipment consist of the following (in thousands):


	December 31,
	2020		2019
Laboratory equipment	$	3,022	$	3,511
Leasehold improvements	564		597
Office and computer equipment	111		111
Furniture and fixtures	122		122
Property and equipment, gross	3,819		4,341
Less: accumulated depreciation and amortization	(3,459)		(3,733)
Property and equipment, net	$	360	$	608

Depreciation and amortization expense for the years ended December 31, 2020 and 2019 was $0.4 million and $0.7 million, respectively. The Company disposed of lab equipment during the year ended December 31, 2020 totaling $0.7 million.

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,
	2020		2019
Accrued employee compensation and benefits	$	2,998	$	3,109
Accrued external research and development expenses	1,870		1,799
Accrued professional fees and other	626		1,450
Total accrued expenses and other current liabilities	$	5,494	$	6,358

DEBT FINANCING

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

DEBT FINANCING

Long-term debt consisted of the following (in thousands):


	December 31,
	2020		2019
Principal amount of long-term debt	$	26,000	$	26,000
Debt discount	(308)		(456)
Deferred financing fees	(470)		(647)

Long-term debt, net of discount	$	25,222	$	24,897

In January 2018, the Company entered into a Loan and Security Agreement. Under the Loan and Security Agreement, the 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 is LIBOR plus 8.50% per annum.

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 February 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 0.2% floor to the LIBOR rate. The Company paid $39,000 to the lender for the amended agreement.

The Company achieved two of the specified regulatory and clinical milestones and the date on which repayment of principal commences was extended to February 2022. The monthly principal payments of $2.2 million will be paid over a period of 12 months. The interest rate was 8.70% as of December 31, 2020.

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 $1.1 million and $0.9 million at December 31, 2020 and 2019, respectively, and is classified within other long-term liabilities.

The scheduled principal maturity of the long term debt as of December 31, 2020 is as follows (in thousands):


Year Ending December 31,
2021	$	—
2022	23,833
2023	2,167
	$	26,000

STOCKHOLDERS' EQUITY	12 Months Ended
STOCKHOLDERS' EQUITY	Dec. 31, 2020
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Redeemable Convertible Preferred Stock Upon the closing of the IPO in 2019, all outstanding 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. Common Stock In May 2019, the Company issued 3,571,428 common shares at a public offering price of $20.00 per share for net proceeds of $64.5 million, after deducting underwriting discounts and commissions and other offering expenses. Additionally, in May 2019, the Company restated its certificate of incorporation, which, among other things: (i) authorized 160,000,000 shares, consisting of (i) 150,000,000 shares of common stock, $0.001 par value per share, and (ii) 10,000,000 shares of undesignated preferred stock, $0.001 par value per share. 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 for net proceeds of approximately $55.9 million, after deducting the underwriting discounts, commissions, and other offering expenses. 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 $35.0 million from time to time through SVB Leerink, acting as its agent (the “ATM Offering”). During the year ended December 31, 2020, the Company sold an aggregate of 1,721,267 shares of its common stock under the ATM Offering for net cash proceeds of $9.3 million, after deducting commissions and expenses of $0.5 million.

STOCK-BASED COMPENSATION

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

2019 Stock Option and Incentive Plan

The 2019 Stock Option and Incentive Plan (the "2019 Plan") was approved by the Company's board of directors on April 29, 2019. 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. Awards under the 2019 plan generally vest ratably over the vesting period (3-4 years) and have a maximum term of 10 years. The number of shares initially reserved for issuance under the 2019 Plan is 905,000, which was increased on January 1, 2020 and will be increased each January 1 thereafter by 4% of the number of shares of the Company's common stock outstanding on the immediately preceding December 31, or such lesser number of shares determined by the Company's board of directors or compensation committee of the board of directors. The number of options available for future grant under the 2019 Plan was 936,148 as of December 31, 2020.

2019 Employee Stock Purchase Plan

The 2019 Employee Stock Purchase Plan (the "2019 ESPP") was approved by our board of directors on April 29, 2019. A total of 237,181 shares of common stock were initially reserved for issuance under this plan, which was cumulatively increased on January 1, 2020 and will be increased each January 1 thereafter by 1% of the number of shares of the Company's common stock outstanding on the immediately preceding December 31, or such lesser number of shares determined by the Company's board of directors or compensation committee of the board of directors.

The number of shares available for future grant was 429,026 as of December 31, 2020. The Company recorded $0.1 million of stock-based compensation expense during the year ended December 31, 2020. No such expense was recorded during the year ended December 31, 2019 related to the 2019 ESPP.

In connection with all share-based payment awards, total stock-based compensation expense recognized was as follows (in thousands):


	December 31,
	2020		2019
Research and development	$	2,670	$	2,461
General and administrative	3,617		3,363
Total stock-based compensation expense	$	6,287	$	5,824

Fair Value of Stock Awards

The fair value of each option issued was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions:


	Year Ending December 31,
	2020		2019
Risk-free interest rate	1.01	%	2.09	%
Expected option life (in years)	5.97		6.16
Expected dividend yield	0	%	0	%
Expected volatility	79	%	71	%

The following table summarizes the Company’s stock option activity for the year ended December 31, 2020:


	Options	Weighted Average Exercise Price		Weighted Average Remaining Life (in Years)	Intrinsic Value (in thousands)
Outstanding as of January 1, 2020	5,176,944	$	7.35
Granted	1,021,940	4.57
Exercised	(4,071)	1.12
Cancelled	(1,274,853)	8.91
Outstanding as of December 31, 2020	4,919,960	$	6.37	7.04	$	2,343
Exercisable as of December 31, 2020	3,015,220	$	6.59	6.16	$	1,459
Vested or expected to vest as of December 31, 2020	4,894,960	$	6.36	7.00	$	2,298

The intrinsic value of options exercised during the year ended December 31, 2020 was nominal. The intrinsic value of options exercised during the year ended December 31, 2019 was $0.4 million.

The weighted-average grant date fair value of the options granted during the years ended December 31, 2020 and 2019, was $3.06 and $7.21 per share, respectively.

As of December 31, 2020, there was $6.7 million of unrecognized compensation expense related to unvested stock options that is expected to be recognized over a weighted-average period of approximately 2.1 years.

Restricted Stock Units

The fair values of restricted stock units are based on the market value of the Company's common stock on the date of grant. The following table summarizes the Company's restricted stock unit activity for the year ended December 31, 2020:


	Number of Shares	Weighted Average Grant Date Fair Value per Share
Outstanding as of January 1, 2020	66,801	$	3.40
Granted	401,166	4.05
Vested	—	—
Forfeited	(120,380)	3.72
Outstanding as of December 31, 2020	347,587	$	4.04

As of December 31, 2020, there was $1.0 million of unrecognized compensation expense related to unvested stock options that is expected to be recognized over a weighted-average period of approximately 1.8 years.

INCOME TAXES

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

INCOME TAXES

There is no provision for income taxes because the Company has historically incurred operating losses and maintains a full valuation allowance against its deferred tax assets. A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations as of December 31, 2020 and 2019 are as follows:


	December 31,
	2020		2019
Tax at U.S. statutory rate	21.0	%	21.0	%
State taxes, net of federal benefit	6.1	%	6.0	%
Permanent differences	(0.8)	%	(1.9)	%
Tax credits	3.0	%	4.1	%
Other	0.3	%	—	%
Change in valuation allowance	(29.6)	%	(29.2)	%
Effective income tax rate	0.0	%	0.0 %

Significant components of the Company’s deferred tax asset at December 31, 2020 and 2019 are as follows (in thousands):


	December 31,
	2020		2019
Net operating loss carryforwards	$	65,911	$	52,242
Research and development tax credit carryforwards	8,896		7,917
Start-up costs	28		35
Capitalized research and development costs	64		169
Depreciation	304		413
Accrued expenses	1,059		1,102
Stock-based compensation	3,253		1,087
Other items	1,175		971
Total deferred tax assets	80,690		63,936
Valuation allowance	(80,690)		(63,936)
Net deferred tax asset	$	—	$	—

As of December 31, 2020, the Company had federal and state net operating loss carryforwards of $242.5 million and $237.3 million, respectively, which may be used to offset future taxable income, if any. These amounts begin to expire in 2030. The federal net operating losses generated in 2018, 2019 and 2020 can be carried forward indefinitely. As of December 31, 2020, the Company had federal and state research and development tax credit carryforwards of $7.0 million and $2.5 million, respectively. These amounts expire at various dates through 2040. Due to the degree of uncertainty related to the ultimate use of the deferred tax assets, the Company has fully reserved these tax benefits, as the determination of the realization of the deferred tax benefits was not determined to be more likely than not. The valuation allowance increased in 2020 by $16.8 million, due to the increase in deferred tax assets by the same amount (primarily due to net operating loss carryforwards) and the Company’s recording of a full valuation allowance.

Utilization of the net operating loss and research and development credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986 due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes may limit the amount of net operating loss and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. As of December 31, 2020, the Company had not yet completed an analysis of whether its net operating loss and research and development credit carryforwards may be limited.

At December 31, 2020 and 2019, the Company had no unrecognized tax benefits. Furthermore, as of December 31, 2020 and 2019, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in our consolidated statements of operations. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense.

The Company files income tax returns in the U.S. Federal, California, Massachusetts, New Jersey, New York, and Pennsylvania jurisdictions. The statute of limitations for assessment by the Internal Revenue Service, or IRS, and state tax authorities is closed for tax years prior to 2017, although carryforward attributes that were generated prior to tax year 2017 may still be adjusted upon examination by the IRS or state tax authorities if they either have been or will be used in a future period. There are currently no federal or state audits in progress.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Leases

The Company leases laboratory and office space under a lease agreement that expires on April 30, 2024. The lease agreement and most recent amendment contained escalating rent payments. Rent expense is recorded on a straight-line basis. The Company is obligated to make minimum lease payments under the facility lease as follows (in thousands):


Years Ending December 31,
2021	$	1,507
2022	1,672
2023	1,722
2024	580
Total	$	5,481

Rent expense in each of the years ended December 31, 2020 and 2019 was $1.3 million and $1.2 million, respectively.

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 by 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

The Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to such legal proceedings.

NET LOSS PER SHARE

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

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):


	December 31,
	2020		2019
Numerator:
Net loss	$	(56,527)	$	(59,037)
Accretion of redeemable convertible preferred stock	—		(46)
Net loss attributable to common stockholders	$	(56,527)	$	(59,083)
Denominator:
Weighted average common shares outstanding, basic and diluted	31,747,676		16,624,941
Net loss per share, basic and diluted	$	(1.78)	$	(3.55)

The Company excluded the following potential shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	December 31,
	2020	2019
Options to purchase common stock	4,919,960	5,176,944
Unvested restricted stock units	347,587	—
Shares issuable under employee stock purchase plan	9,830	—
	5,277,377	5,176,944

401(k) PLAN	12 Months Ended
401(k) PLAN	Dec. 31, 2020
Retirement Benefits [Abstract]
401(k) PLAN	401(k) PLANThe Company has a 401(k) retirement and savings plan (the "Plan") covering all qualified employees. The Plan allows each participant to contribute a portion of his or her base wages up to an amount not to exceed an annual statutory maximum. The Company is permitted to make discretionary matching contributions to the Plan. As of December 31, 2020, the Company's matching contributions totaled $0.3 million. The Company did not make matching contributions as part of the Plan as of December 31, 2019.

- Definition

The entire disclosure for retirement benefits.

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+ Details

RELATED- PARTY TRANSACTIONS	12 Months Ended
RELATED- PARTY TRANSACTIONS	Dec. 31, 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 year ended December 31, 2020 and 2019 was $0.3 million and $0.3 million, respectively. As of December 31, 2020 and 2019 there were no amounts payable to the Chairman for costs related to the consulting agreement.

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSThe Company has evaluated subsequent events for financial statement purposes occurring through March 17, 2021, the date that these consolidated financial statements were issued, and determined that there are no material recognized or unrecognized subsequent events requiring disclosure.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

Principles of 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

Cash and Cash Equivalents

Marketable Securities

Concentrations of Credit Risk

Fair Value Measurements

•Level 1 — Quoted prices in active markets for identical assets or liabilities.

Property and Equipment

Property and equipment are recorded at cost. Depreciation and amortization is calculated using the straight-line method over the following estimated useful lives of the assets:


			Estimated useful life
Computer equipment and software			3 years
Office equipment			3 - 5 years
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of the asset’s estimated useful life or the remaining lease term

Impairment of Long-Lived Assets

Research and Development Costs

Stock-Based Compensation

The Company classifies stock-based compensation expense in the consolidated statements of operations in the same manner in which the award recipient’s cash compensation costs are classified.

Income Taxes

Comprehensive Loss

Comprehensive LossComprehensive 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.

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.

Recently Adopted Accounting Pronouncements and Accounting Pronouncements Issued and Not Adopted

Recently Adopted Accounting Pronouncements

Accounting Pronouncements Issued and Not Adopted

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Property and Equipment

Depreciation and amortization is calculated using the straight-line method over the following estimated useful lives of the assets:


			Estimated useful life
Computer equipment and software			3 years
Office equipment			3 - 5 years
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of the asset’s estimated useful life or the remaining lease term

Property and equipment consist of the following (in thousands):


	December 31,
	2020		2019
Laboratory equipment	$	3,022	$	3,511
Leasehold improvements	564		597
Office and computer equipment	111		111
Furniture and fixtures	122		122
Property and equipment, gross	3,819		4,341
Less: accumulated depreciation and amortization	(3,459)		(3,733)
Property and equipment, net	$	360	$	608

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

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 (in thousands):


	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


	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

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES (Tables)

12 Months Ended

Dec. 31, 2020

Cash and Cash Equivalents [Abstract]

Schedule of Cash, Cash Equivalents and Marketable Securities

As of December 31, 2020 and 2019, cash, cash equivalents, and marketable securities by security type consisted of the following (in thousands):


	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


	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value




Cash and cash equivalents	$	92,053	$	—	$	—	$	92,053
Corporate obligations	—		—		—		—
Total	$	92,053	$	—	$	—	$	92,053

Investments Classified by Contractual Maturity Date

The fair values of cash equivalents and marketable securities by contractual maturity were as follows (in thousands):


	December 31,
Contractual maturities	2020		2019
Mature in one year or less	$	86,338	$	91,803
Mature in two years or less	18,519		—
Total	$	104,857	$	91,803

PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

Depreciation and amortization is calculated using the straight-line method over the following estimated useful lives of the assets:


			Estimated useful life
Computer equipment and software			3 years
Office equipment			3 - 5 years
Laboratory equipment			5 years
Furniture and fixtures			5 years
Leasehold improvements			Shorter of the asset’s estimated useful life or the remaining lease term

Property and equipment consist of the following (in thousands):


	December 31,
	2020		2019
Laboratory equipment	$	3,022	$	3,511
Leasehold improvements	564		597
Office and computer equipment	111		111
Furniture and fixtures	122		122
Property and equipment, gross	3,819		4,341
Less: accumulated depreciation and amortization	(3,459)		(3,733)
Property and equipment, net	$	360	$	608

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES Payables and Accruals (Tables)

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

Schedule of Accrued Expenses and Other Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	December 31,
	2020		2019
Accrued employee compensation and benefits	$	2,998	$	3,109
Accrued external research and development expenses	1,870		1,799
Accrued professional fees and other	626		1,450
Total accrued expenses and other current liabilities	$	5,494	$	6,358

DEBT FINANCING (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Summary of Long-term Debt

Long-term debt consisted of the following (in thousands):


	December 31,
	2020		2019
Principal amount of long-term debt	$	26,000	$	26,000
Debt discount	(308)		(456)
Deferred financing fees	(470)		(647)

Long-term debt, net of discount	$	25,222	$	24,897

Schedule of Maturities of Long-term Debt

The scheduled principal maturity of the long term debt as of December 31, 2020 is as follows (in thousands):


Year Ending December 31,
2021	$	—
2022	23,833
2023	2,167
	$	26,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Summary of Stock Based Compensation Expense

In connection with all share-based payment awards, total stock-based compensation expense recognized was as follows (in thousands):


	December 31,
	2020		2019
Research and development	$	2,670	$	2,461
General and administrative	3,617		3,363
Total stock-based compensation expense	$	6,287	$	5,824

Summary of Fair Value Assumptions for Stock Options

The fair value of each option issued was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions:


	Year Ending December 31,
	2020		2019
Risk-free interest rate	1.01	%	2.09	%
Expected option life (in years)	5.97		6.16
Expected dividend yield	0	%	0	%
Expected volatility	79	%	71	%

Summary of Options Activity

The following table summarizes the Company’s stock option activity for the year ended December 31, 2020:


	Options	Weighted Average Exercise Price		Weighted Average Remaining Life (in Years)	Intrinsic Value (in thousands)
Outstanding as of January 1, 2020	5,176,944	$	7.35
Granted	1,021,940	4.57
Exercised	(4,071)	1.12
Cancelled	(1,274,853)	8.91
Outstanding as of December 31, 2020	4,919,960	$	6.37	7.04	$	2,343
Exercisable as of December 31, 2020	3,015,220	$	6.59	6.16	$	1,459
Vested or expected to vest as of December 31, 2020	4,894,960	$	6.36	7.00	$	2,298

Share-based Payment Arrangement, Restricted Stock Unit, Activity

The following table summarizes the Company's restricted stock unit activity for the year ended December 31, 2020:


	Number of Shares	Weighted Average Grant Date Fair Value per Share
Outstanding as of January 1, 2020	66,801	$	3.40
Granted	401,166	4.05
Vested	—	—
Forfeited	(120,380)	3.72
Outstanding as of December 31, 2020	347,587	$	4.04

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations as of December 31, 2020 and 2019 are as follows:


	December 31,
	2020		2019
Tax at U.S. statutory rate	21.0	%	21.0	%
State taxes, net of federal benefit	6.1	%	6.0	%
Permanent differences	(0.8)	%	(1.9)	%
Tax credits	3.0	%	4.1	%
Other	0.3	%	—	%
Change in valuation allowance	(29.6)	%	(29.2)	%
Effective income tax rate	0.0	%	0.0 %

Schedule of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax asset at December 31, 2020 and 2019 are as follows (in thousands):


	December 31,
	2020		2019
Net operating loss carryforwards	$	65,911	$	52,242
Research and development tax credit carryforwards	8,896		7,917
Start-up costs	28		35
Capitalized research and development costs	64		169
Depreciation	304		413
Accrued expenses	1,059		1,102
Stock-based compensation	3,253		1,087
Other items	1,175		971
Total deferred tax assets	80,690		63,936
Valuation allowance	(80,690)		(63,936)
Net deferred tax asset	$	—	$	—

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments

The Company is obligated to make minimum lease payments under the facility lease as follows (in thousands):


Years Ending December 31,
2021	$	1,507
2022	1,672
2023	1,722
2024	580
Total	$	5,481

NET LOSS PER SHARE (Tables)

12 Months Ended

Dec. 31, 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):


	December 31,
	2020		2019
Numerator:
Net loss	$	(56,527)	$	(59,037)
Accretion of redeemable convertible preferred stock	—		(46)
Net loss attributable to common stockholders	$	(56,527)	$	(59,083)
Denominator:
Weighted average common shares outstanding, basic and diluted	31,747,676		16,624,941
Net loss per share, basic and diluted	$	(1.78)	$	(3.55)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	December 31,
	2020	2019
Options to purchase common stock	4,919,960	5,176,944
Unvested restricted stock units	347,587	—
Shares issuable under employee stock purchase plan	9,830	—
	5,277,377	5,176,944

NATURE OF BUSINESS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 272,613	$ 216,086
Cash, cash equivalents and marketable securities	$ 107,300

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 segment
Accounting Policies [Abstract]
Number of operating segments	1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment Useful Life (Details)	12 Months Ended
	Dec. 31, 2020
Computer equipment and software
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Corporate obligations	$ 107,329	$ 92,053
Corporate obligations
Assets:
Cash equivalents	71,590	92,053
Corporate obligations	35,739	0
Fair Value, Recurring
Assets:
Cash equivalents	69,118	91,803
Total	104,857	91,803
Fair Value, Recurring \| Corporate obligations
Assets:
Corporate obligations	35,739
Fair Value, Recurring \| Level 1
Assets:
Cash equivalents	69,118	91,803
Total	69,118	91,803
Fair Value, Recurring \| Level 1 \| Corporate obligations
Assets:
Corporate obligations	0
Fair Value, Recurring \| Level 2
Assets:
Cash equivalents	0	0
Total	35,739	0
Fair Value, Recurring \| Level 2 \| Corporate obligations
Assets:
Corporate obligations	35,739
Fair Value, Recurring \| Level 3
Assets:
Cash equivalents	0	0
Total	0	$ 0
Fair Value, Recurring \| Level 3 \| Corporate obligations
Assets:
Corporate obligations	$ 0

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Amortized Cost	$ 71,590	$ 92,053
Amortized Cost	107,363	92,053
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(35)	0
Estimated Fair Value	107,329	92,053
Corporate obligations
Cash and Cash Equivalents [Line Items]
Amortized Cost	35,773	0
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(35)	0
Cash and cash equivalents, estimated fair value	71,590	92,053
Estimated Fair Value	$ 35,739	$ 0

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES - Contractual Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Mature in one year or less	$ 86,338	$ 91,803
Mature in two years or less	18,519	0
Total	$ 104,857	$ 91,803

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash	$ 2.5	$ 0.3

PROPERTY AND EQUIPMENT - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,819	$ 4,341
Less: accumulated depreciation and amortization	(3,459)	(3,733)
Property and equipment, net	360	608
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,022	3,511
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	564	597
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	111	111
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 122	$ 122

PROPERTY AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 419	$ 662
Laboratory equipment
Property, Plant and Equipment [Line Items]
Disposal of lab equipment	$ 700