Applied Therapeutics (APLT) 10-K 18 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Entity Registrant Name	Applied Therapeutics Inc.
Title of 12(b) Security	Common Stock
Trading Symbol	APLT
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	true
Entity Shell Company	false
ICFR Auditor Attestation Flag	false
Entity Public Float			$ 659,242,807
Entity Common Stock, Shares Outstanding		26,009,399
Entity Central Index Key	0001697532
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 57,466	$ 18,850
Investments	39,363	20,004
Prepaid expenses and other current assets	5,764	7,301
Total current assets	102,593	46,155
Operating lease right-of-use asset	1,712	2,035
Security deposits and leasehold improvements	201	199
TOTAL ASSETS	104,506	48,389
CURRENT LIABILITIES:
Current portion of operating lease liabilities	406	356
Accounts payable	640	8,793
Accrued expenses and other current liabilities	20,189	4,950
Total current liabilities	21,235	14,099
NONCURRENT LIABILITIES:
Noncurrent portion of operating lease liabilities	1,332	1,683
Total noncurrent liabilities	1,332	1,683
Total liabilities	22,567	15,782
STOCKHOLDERS’ EQUITY (DEFICIT):
Common stock, $0.0001 par value; 100,000,000 shares authorized as of December 31, 2020 and December 31, 2019; 22,493,661 shares and 18,531,560 shares issued and outstanding as of December 31, 2020 and December 31, 2019, respectively	2	1
Additional paid-in capital	242,780	99,378
Accumulated other comprehensive loss	(112)	(2)
Accumulated deficit	(160,731)	(66,770)
Total stockholders' equity	81,939	32,607
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 104,506	$ 48,389

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Balance Sheets
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized (in shares)	10,000,000	10,000,000
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, authorized (in shares)	100,000,000	100,000,000
Common Stock, issued (in shares)	22,493,661	18,531,560
Common stock, outstanding (in shares)	22,493,661	18,531,560

Statements of Operations

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
OPERATING EXPENSES:
Research and development	$ 61,788	$ 32,350
General and administrative	32,678	13,232
Total operating expenses	94,466	45,582
LOSS FROM OPERATIONS	(94,466)	(45,582)
OTHER INCOME (EXPENSE), NET:
Interest income (expense), net	559	93
Other income (expense)	(54)	(24)
Total other income (expense), net	505	69
Net loss	(93,961)	(45,513)
Net loss attributable to common stockholders—basic	(93,961)	(45,513)
Net loss attributable to common stockholders— diluted	$ (93,961)	$ (45,513)
Net loss per share attributable to common stockholders—basic and diluted	$ (4.28)	$ (3.55)
Weighted-average common stock outstanding—basic and diluted	21,966,326	12,831,221

Statements of Comprehensive Inc

Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statements of Comprehensive Income (Loss)
Net loss	$ (93,961)	$ (45,513)
Other comprehensive income (loss)
Unrealized gain (loss) on marketable securities	(110)	(2)
Other comprehensive gain (loss), net of tax	(110)	(2)
Comprehensive income (loss), net of tax	$ (94,071)	$ (45,515)

Statement of Convertible Prefer

Statement of Convertible Preferred Stock $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)shares
Series A Convertible Preferred Stock
Increase (Decrease) in Temporary Equity
Balance at beginning of period | $	$ 6,254
Balance at beginning of period (in shares) | shares	3,093,898
Conversion of convertible preferred stock into common stock upon closing of initial public offering | $	$ (6,254)
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares) | shares	(3,093,898)
Series B Convertible Preferred Stock
Increase (Decrease) in Temporary Equity
Balance at beginning of period | $	$ 29,156
Balance at beginning of period (in shares) | shares	4,001,848
Issuance of convertible preferred stock for cash, net of issuance costs | $	$ 2,897
Issuance of convertible preferred stock for cash, net of issuance costs (in shares) | shares	442,925
Conversion of convertible preferred stock into common stock upon closing of initial public offering | $	$ (32,053)
Conversion of convertible preferred stock into common stock upon closing of initial public offering (in shares) | shares	(4,444,773)

Statement of Convertible Pref_2

Statement of Convertible Preferred Stock (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Series B Convertible Preferred Stock
Issuance of convertible preferred stock for cash, issuance costs	$ 419

Statement of Stockholders' (Def

Statement of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Common StockSeries A Convertible Preferred Stock	Common StockSeries B Convertible Preferred Stock	Common StockIPO	Common StockPrivate placement	Common StockSecondary public offering	Common Stock	Additional Paid-in CapitalSeries A Convertible Preferred Stock	Additional Paid-in CapitalSeries B Convertible Preferred Stock	Additional Paid-in CapitalIPO	Additional Paid-in CapitalPrivate placement	Additional Paid-in CapitalSecondary public offering	Additional Paid-in CapitalRegistration of Form S-3 offering/Shelf Registration Statement	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	IPO	Private placement	Secondary public offering	Registration of Form S-3 offering/Shelf Registration Statement	Total
Balance at Dec. 31, 2018													$ 1,665	$ (21,257)								$ (19,592)
Balance (in shares) at Dec. 31, 2018						5,513,531
Increase (Decrease) in Stockholders' Equity
Issuance of common stock warrants in connection with the issuance													80									80
Conversion of convertible preferred stock into common stock upon closing of the IPO		$ 1					$ 6,254	$ 32,052								$ 6,254	$ 32,053
Conversion of convertible preferred stock into common stock upon closing of the IPO (in shares)	3,093,898	4,444,773
Issuance of common stock									$ 34,582	$ 18,348								$ 34,582	$ 18,348
Issuance of common stock (in shares)			4,000,000	1,380,344
Exercise of options for common stock issued under equity incentive plan													226									226
Exercise of options for common stock issued under equity incentive plan (in shares)						81,988
Exercise of warrants of common stock (in shares)						17,026
Stock-based compensation expense													6,171									6,171
Net loss														(45,513)								(45,513)
Other comprehensive income (loss)															$ (2)							(2)
Balance at Dec. 31, 2019						$ 1							99,378	(66,770)	(2)							32,607
Balance (in shares) at Dec. 31, 2019						18,531,560
Increase (Decrease) in Stockholders' Equity
Issuance of common stock					$ 1						$ 134,101									$ 134,102
Issuance of common stock (in shares)					3,152,712																3,450,000
Exercise of options for common stock issued under equity incentive plan						$ 0							1,817									$ 1,817
Exercise of options for common stock issued under equity incentive plan (in shares)						522,160																522,160
Issuance costs										$ (47)		$ (495)							$ (47)		$ (495)
Exercise of warrants of common stock (in shares)						287,229
Stock-based compensation expense													8,026									$ 8,026
Net loss														(93,961)								(93,961)
Other comprehensive income (loss)															(110)							(110)
Balance at Dec. 31, 2020						$ 2							$ 242,780	$ (160,731)	$ (112)							$ 81,939
Balance (in shares) at Dec. 31, 2020						22,493,661

Statement of Stockholders' (D_2

Statement of Stockholders' (Deficit) Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
IPO
Increase (Decrease) in Stockholders' Equity
Stock issuance cost		$ 5,417
Private placement
Increase (Decrease) in Stockholders' Equity
Stock issuance cost		$ 1,667
Secondary public offering
Increase (Decrease) in Stockholders' Equity
Stock issuance cost	$ 739
Common Stock
Increase (Decrease) in Stockholders' Equity
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (93,961)	$ (45,513)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	8,026	6,171
Amortization of insurance premium	2,552
Amortization of operating lease right-of-use assets	380	23
Payment of security deposit and leasehold improvements for long-term lease	(2)	(199)
Change in operating lease liability	(358)	(19)
Changes in operating assets and liabilities:
Financed insurance premium	(3,222)
Prepaid expenses	2,207	(5,922)
Accounts payable	(8,044)	5,751
Accrued expenses and other current liabilities	14,213	3,401
Net cash used in operating activities	(78,209)	(36,307)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of available-for-sale securities	(134,659)	(20,006)
Proceeds from sale of available-for-sale securities	17,109
Proceeds from maturities of available-for-sale securities	98,081
Net cash used in investing activities	(19,469)	(20,006)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of Series B convertible preferred stock, net of cash issuance costs of $340		2,977
Proceeds from issuance of Private Placement stock, net of cash issuance costs of $1,509		18,510
Proceeds from secondary public offering, net of cash issuance costs of $739	134,102
Payment of IPO costs		(2,498)
Proceeds from the IPO, net of underwriter commissions		37,200
Proceeds from financed insurance premium	3,222
Repayments of short-term borrowings	(2,148)
Exercise of stock options for common stock under equity incentive plan	1,817	226
Net cash provided by financing activities	136,294	56,415
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	38,616	102
Cash and cash equivalents at beginning of period	18,850	18,748
Cash and cash equivalents at end of period	57,466	18,850
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Operating lease right-of-use asset obtained in exchange for operating lease liability	57	2,096
Unrealized gain (loss) on marketable securities	(110)
Conversion of preferred stock to equity following the IPO		38,307
Series B Convertible Preferred Stock
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Issuance of warrants in connection with Series B convertible preferred stock		80
Private placement
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs	(206)
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Stock issuance costs in accrued expenses		135
Stock issuance costs in accounts payable		$ 27
Registration of Form S-3 offering/Shelf Registration Statement
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs	(493)
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Stock issuance costs in accrued expenses	$ 2

Statements of Cash Flows (Paren

Statements of Cash Flows (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Statements of Cash Flows
Cash issuance costs, Convertible preferred stock	$ 340
Cash issuance costs, Private Placement	1,509
Cash issuance costs, Secondary public offering	$ 739

ORGANIZATION AND SUMMARY OF SIG

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2020
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Operations and Business Applied Therapeutics, Inc. (the “Company”) is a clinical‑stage biopharmaceutical company developing a pipeline of novel product candidates against validated molecular targets in indications of high unmet medical need. In particular, the Company is currently targeting treatments for cardiovascular disease, galactosemia and diabetic complications. The Company was incorporated in Delaware on January 20, 2016 and is headquartered in New York, New York. On May 16, 2019, the Company completed an initial public offering (the “IPO”) in which the Company issued and sold 4,000,000 shares of its common stock at a public offering price of $10.00 per share, for aggregate gross proceeds of $40.0 million. The Company received net proceeds of $34.6 million, after deducting underwriting discounts and commissions and offering costs. Prior to the completion of the IPO, the Company primarily funded its operations with proceeds from the sale of convertible preferred stock (see Note 10). In connection with the IPO, the Company effected a 55.2486-for-1 stock split of its issued and outstanding shares of common stock and convertible preferred stock. The stock split became effective on April 26, 2019. Stockholders entitled to fractional shares as a result of the forward stock split received cash payment in lieu of receiving fractional shares. All share and per share amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect this stock split. Shares of common stock underlying outstanding stock options and other equity instruments were proportionately increased and the respective per share value and exercise prices, if applicable, were proportionately decreased in accordance with the terms of the agreements governing such securities. Upon the closing of the IPO on May 16, 2019, all of the then-outstanding shares of convertible preferred stock automatically converted into 7,538,671 shares of common stock on a one-for-one basis. Subsequent to the closing of the IPO, there were no shares of convertible preferred stock outstanding. On November 12, 2019, the Company completed a private placement (the “Private Placement”), pursuant to which it issued and sold 1,380,344 shares of the Company’s common stock at a price of $14.50 per share, for net proceeds of $18.4 million after deducting placement agent discounts and commissions and offering costs. On January 28, 2020, the Company completed its secondary public offering (the “Secondary Public Offering”), pursuant to which it issued and sold 2,741,489 shares of common stock at a public offering price of $45.50 per share, with an additional 411,223 shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares. The aggregate net proceeds received by the Company from the offering, after deducting underwriting discounts and commissions and offering costs, were $134.1 million. On June 4, 2020, the Company filed a shelf registration statement on Form S-3 (the “Shelf Registration Statement”) under which the Company may, from time to time, sell securities in one or more offerings having an aggregate offering price of up to $300.0 million. The Shelf Registration Statement was declared effective as of June 15, 2020. As of the filing date of this Annual Report, the Company has sold 3,450,000 shares of common stock under this shelf registration. On June 12, 2020, the Company entered into an equity distribution agreement (the “Equity Distribution Agreement”) with Goldman Sachs & Co. LLC (“Goldman”), as a sales agent to sell shares of the Company’s common stock, from time to time, having an aggregate offering price of up to $100 million. Goldman may act as an agent on the Company’s behalf or purchase shares of the Company’s common stock as a principal. As of December 31, 2020, the Company had not sold any shares of common stock pursuant to the Equity Distribution Agreement. On February 17, 2021, the Company completed an underwritten public offering (the “February Offering”) of 3,450,000 shares of common stock, including the exercise in full of the underwriters’ option to purchase 450,000 additional shares of common stock, which option closed on February 19, 2021. The shares were offered at a price to the public of $23.00 per share, resulting in aggregate net proceeds of approximately $74.3 million , after deducting underwriting discounts and commissions and estimated offering expenses. Liquidity The Company has incurred, and expects to continue to incur, significant operating losses and negative cash flows for at least the next several years as it continues to develop its drug candidates. To date, the Company has not generated any revenue, and it does not expect to generate revenue unless and until it successfully completes development and obtains regulatory approval for one of its product candidates. Management believes that the Company’s existing cash, together with the net proceeds from the S econdary Public Offering and the February Offering, will allow the Company to continue its operations for at least 12 months from the issuance date of these financial statements. If the Company is unable to obtain additional funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. Risks and Uncertainties The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and reliance on third party manufacturers. Use of Estimates The preparation of financial statements in conformity with U.S. 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 financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Significant Accounting Policies Fair Value Measurements Certain assets and liabilities are reported on a recurring basis 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 and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Cash and Cash Equivalents The Company considers all short‑term, highly liquid investments, with an original maturity of three months or less, to be cash equivalents. The Company maintains its cash in bank deposit accounts which, at times, may exceed federally insured limits. The Company has not experienced any losses in these accounts and does not believe it is exposed to any significant credit risk on cash and cash equivalents. Investments The Company has investments in marketable debt securities. The Company determines the appropriate classification of its investments at the date of purchase and reevaluate the classifications at the balance sheet date. Marketable debt securities with maturities of 12 months or less are classified as short-term. Marketable debt securities with maturities greater than 12 months are classified as long-term. The Company’s marketable securities are accounted for as available for sale (“AFS”). AFS securities are reported at fair value. Unrealized gains and losses, after applicable income taxes, are reported in accumulated other comprehensive income/(loss). Realized gains or losses on the sale of marketable securities are determined using the specific identification method and are recorded as a component of other income (expense), net. The Company conducts an other-than-temporary impairment (“OTTI”) analysis on a quarterly basis or more often if a potential loss-triggering event occurs. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and whether the Company intends to sell. For AFS securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis and (ii) the amortized cost basis cannot be recovered as a result of credit losses. The Company adopted ASU No. 2016-13, “Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” on January 1, 2020 and applied the new modified credit impairment guidance related to available-for-sale debt securities prospectively. Under the new guidance, at each reporting date, entities must evaluate their individual available-for-sale debt securities that are in an unrealized loss position and determine whether the decline in fair value below the amortized cost basis from a credit loss or other factors. The amount of the decline related to credit losses is recorded as a credit loss expense in earnings with a corresponding allowance for credit losses and the amount of decline not related to credit losses are recorded through other comprehensive income, net of tax. Leases At the inception of an arrangement, the Company determines if an arrangement is, or contains, a lease based on the unique facts and circumstances present in that arrangement. Lease classification, recognition, and measurement are then determined at the lease commencement date. For arrangements that contain a lease the Company (i) identifies lease and non-lease components, (ii) determines the consideration in the contract, (iii) determines whether the lease is an operating or financing lease; and (iv) recognizes lease ROU assets and liabilities. Lease liabilities and their corresponding ROU assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable and as such, the Company uses its incremental borrowing rate based on the information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. Most leases include options to renew and, or, terminate the lease, which can impact the lease term. The exercise of these options is at the Company’s discretion and the Company does not include any of these options within the expected lease term as the Company is not reasonably certain it will exercise these options. The Company has elected to combine lease components (for example fixed payments including rent) with non-lease components (for example, non-dedicated parking and common-area maintenance costs) on our real estate asset classes. Fixed, or in substance fixed, lease payments on operating leases are recognized over the expected term of the lease on a straight-line basis. Fixed lease expense on operating leases is recognized within operating expenses within the statements of operations. The Company has operating leases for our corporate offices. The Company has elected the short-term lease exemption and, therefore, do not recognize a ROU asset or corresponding liability for lease arrangements with an original term of 12 months or less. Leasehold improvements and assets under financing lease arrangements are amortized over the lesser of the asset’s estimated useful life or the term of the respective lease. Maintenance costs are expensed as incurred. Operating leases are included in operating lease right-of-use asset, current portion of operating lease liabilities, and noncurrent portion of operating lease liabilities in the balance sheet as of December 31, 2020 and 2019. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in the statement of stockholders’ (deficit) equity as a reduction of proceeds generated as a result of the offering. Should a planned equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statement of operations. Upon closing the IPO in May 2019, $2.6 million in deferred offering costs were reclassified from prepaid and other current assets and recorded against the IPO proceeds reducing additional paid-in capital. As of December 31, 2020 and 2019, the Company did not have any deferred offering costs recorded in prepaid and other current assets. Common Stock Valuation For all periods prior to the IPO, the Company utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately‑Held Company Equity Securities Issued as Compensation (the “Practice Aid”), to estimate the fair value of its common stock. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to the Company’s common stock at the time of, and the likelihood of, achieving a liquidity event, such as an IPO or sale. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date. Convertible Preferred Stock For all periods prior to the IPO, the Company recorded shares of its convertible preferred stock at their respective fair values on the dates of issuance less issuance costs. The Company classified shares of its convertible preferred stock outside of stockholders’ deficit when the redemption of such units or shares is outside the Company’s control. The Company did not adjust the carrying values of the convertible preferred units or convertible preferred stock to the liquidation preferences of such units or shares until such time as a deemed liquidation event is probable of occurring. Research and Development The Company expenses all costs incurred in performing research and development activities. Research and development expenses include salaries and other related costs, materials and supplies, preclinical expenses, manufacturing expenses, contract services and other outside expenses. As part of the process of preparing the financial statements, the Company is required to estimate their accrued research and development expenses. The Company makes estimates of the accrued expenses as of each balance sheet date in the financial statements based on facts and circumstances known at that time. In addition, there may be instances in which payments made to the Company’s vendors will exceed the level of services provided and result in a prepayment of the expense in which case such amounts are reflected as prepaid expenses and other current assets. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts the accrual or the amount of prepaid expenses accordingly. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized in prepaid expenses and other current assets. The capitalized amounts are expensed as the related goods are delivered or the services are performed. Research and development costs also include costs incurred in connection with certain licensing arrangements. Before a compound receives regulatory approval, the Company records upfront and milestone payments made to third parties under licensing arrangements as expense. Upfront payments are recorded when incurred, and milestone payments are recorded when the specific milestone has been achieved. Once a compound receives regulatory approval, the Company will record any milestone payments in identifiable intangible assets, less accumulated amortization and, unless the asset is determined to have an indefinite life, the Company will amortize the payments on a straight-line basis over the remaining agreement term or the expected product life cycle, whichever is shorter. General and Administrative General and administrative expenses consist primarily of salaries and other related costs, including stock‑based compensation, for personnel in the Company’s executive and finance functions. General and administrative expenses also include professional fees for legal, accounting, auditing, tax and consulting services; travel expenses; and facility‑related expenses, which include allocated expenses for rent and maintenance of facilities and other operating costs. Commercial expenses consist of payroll expense for commercial personnel, as well as marketing, market research, market access, and other focused investments to support launch of drug candidates, generate evidence of commercial potential and value proposition, and maximize potential business development deal leverage. Commercial expenses are included in general and administrative expenses. Stock‑Based Compensation The Company accounts for its stock‑based compensation as expense in the statements of operations based on the awards’ grant date fair values. The Company accounts for forfeitures as they occur by reversing any expense recognized for unvested awards. The Company estimates the fair value of options granted using the Black‑Scholes option pricing model. The Black‑Scholes option pricing model requires inputs based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of the award, (c) the risk‑free interest rate and (d) expected dividends. Due to the lack of a public market for the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The computation of expected volatility is based on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. The Company uses the simplified method as allowed by the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin (“SAB”) No. 107, Share‑Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The fair value of stock‑based payments is recognized as expense over the requisite service period which is generally the vesting period. Stock-Based Compensation–Restricted Stock Units The Company accounts for restricted stock units in accordance with the authoritative guidance for stock-based compensation. The fair value of restricted stock units is measured at the grant date based on the closing market price of the Company’s common stock on the date of grant, and is recognized as expense on a straight-line basis over the period of vesting. Forfeitures are recognized as a reduction of stock-based compensation expense as they occur. Income Taxes The Company uses the asset and liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities at currently enacted tax rates. These temporary differences primarily relate to net operating loss carryforwards available to offset future taxable income. Valuation allowances are established, if necessary, to reduce a deferred tax asset to the amount that will more likely than not be realized. The Company recognizes tax liabilities from an uncertain tax position only if it is more likely than not that the tax position will not be sustained upon examination by the taxing authorities, based on the technical merits of the tax position. There are no uncertain tax positions that have been recognized in the accompanying financial statements. The Company is required to file tax returns in the U.S. federal jurisdiction and in the state of New York. The Company’s policy is to recognize interest and penalties related to uncertain tax benefits, if any, as part of income tax expense. No such interest and penalties have been accrued as of December 31, 2020 and 2019. Net Loss per Share Basic net loss per share is calculated by dividing net loss available to common stockholders by the weighted‑average common stock outstanding. Diluted net loss per share is calculated similarly, except that it includes the dilutive effect of the assumed exercise of securities, including outstanding warrants and the effect of shares issuable under the Company’s stock‑based compensation plan, if such effect is dilutive. Segment Information Operating segments are defined as components of an enterprise for which separate discrete information is available for evaluation by the chief operating decision‑maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision‑maker, the Company’s chief executive officer, views the Company’s operations and manages its business as a single operating segment, which is the business of discovering and developing its product candidates. Recent Accounting Pronouncements On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (CECL) methodology. The measurement of expected credit losses under the CECL methodology applies to financial instruments measured at amortized cost, including loan receivables and held-to-maturity debt securities, off-balance sheet credit exposures and net investments in leases recognized by a lessor. ASC 326 also made changes to the accounting for available-for-sale debt securities, where credit losses are required to be presented as an allowance as opposed to a write-down. The FASB issued authoritative guidance that amends guidance on reporting credit losses for assets, including available-for-sale marketable securities and any other financial assets not excluded from the scope that have the contractual right to receive cash. For available-for-sale marketable securities, credit losses should be measured in a manner similar to current generally accepted accounting standards; however, ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , will require that credit losses be presented as an allowance rather than as a write-down. For available-for-sale debt securities in an unrealized loss position, the Company assesses whether a decline in fair value resulted from credit losses or other factors. Management considers the extent to which fair value is less than amortized cost, any changes to the credit rating of the security, and adverse conditions specifically related to the security. If the assessment indicates a credit loss exists, an allowance is recorded that is limited to the amount the amortized cost exceeds the fair value. Any impairment that is not recognized through the allowance for credit loss is recognized in other comprehensive income. The Company adopted ASC 326 using the modified retrospective method approach, where a cumulative-effect adjustment to credit loss allowance would be reflected in retained earnings. The adoption of this standard did not have an impact on the Company’s balance sheet as there were no credit losses identified. In August 2018, the FASB issued ASU No. 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement ,” which modifies the disclosure requirements on fair value measurements. The new guidance is effective for fiscal years beginning after December 15, 2019. Upon the effective date, certain provisions are to be applied prospectively, while others are to be applied retrospectively to all periods presented. The amendments eliminated certain disclosure requirements such as the elimination of disclosing the valuation process for Level 3 fair value measurements. Other amendments in the update did not impact the Company. The Company adopted the amendments on January 1, 2020 with no impact on our financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes. The new standard intended to simplify the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. The standard is effective for annual periods beginning after December 15, 2020 and interim periods within, with early adoption permitted. Adoption of the standard requires certain changes to primarily be made prospectively, with some changes to be made retrospectively. The Company adopted the amendment in January 2021, and expects it will have no impact on our financial statements.

LICENSE AGREEMENT

LICENSE AGREEMENT	12 Months Ended
	Dec. 31, 2020
LICENSE AGREEMENT
LICENSE AGREEMENT	2. LICENSE AGREEMENT Columbia University In October 2016, the Company entered into a license agreement (the “ 2016 Columbia Agreement”) with the Trustees of Columbia University (“Columbia University”) to obtain an exclusive royalty-bearing sublicensable license in respect to certain patents. As part of the consideration for entering into the 2016 Columbia Agreement, the Company issued to Columbia University shares equal to 5% of its outstanding common stock on a fully diluted basis at the time of issue. The common stock had a fair value of $0.5 million at the time of issuance. The Company will be required to make further payments to Columbia University of up to an aggregate of $1.3 million for the achievement of specified development and regulatory milestones, and up to an aggregate of $1.0 million for the achievement of a specified level of aggregate annual net sales, in each case in connection with products covered by the 2016 Columbia Agreement. The Company will also be required to pay tiered royalties to Columbia University in the low‑ to mid‑single digit percentages on the Company’s, its affiliates’ and its sublicensees’ net sales of licensed products, subject to specified offsets and reductions. In addition, the Company is required to make specified annual minimum royalty payments to Columbia University, which is contingent upon the approval of the licensed products, in the mid six figures beginning on the 10th anniversary of the effective date of the 2016 Columbia Agreement. The Company has not granted any sublicenses under the 2016 Columbia Agreement. However, if the Company sublicenses the rights granted under the 2016 Columbia Agreement to one or more third parties, it will be required to pay Columbia University a portion of the net sublicensing revenue received from such third parties, at percentages between 10% and 20%, depending on the stage of development at the time such revenue is received from such third parties. The 2016 Columbia Agreement will terminate upon the expiration of all the Company’s royalty payment obligations in all countries. The Company may terminate the 2016 Columbia Agreement for convenience upon 90 days’ written notice to Columbia University. At its election, Columbia University may terminate the 2016 Columbia Agreement, or convert the licenses granted to the Company into non‑exclusive, non‑sublicensable licenses, in the case of (a) the Company’s uncured material breach upon 30 days’ written notice (which shall be extended to 90 days if the Company is diligently attempting to cure such material breach), (b) the Company’s failure to achieve the specified development and funding milestone events, or (c) the Company’s insolvency. In January 2019, the Company entered into a second license agreement with Columbia University (the “2019 Columbia Agreement”). Pursuant to the 2019 Columbia Agreement, Columbia University granted the Company a royalty-bearing, sublicensable license that is exclusive with respect to certain patents, and non-exclusive with respect to certain know-how, in each case to develop, manufacture and commercialize PI3k inhibitor products. The license grant is worldwide. Under the 2019 Columbia Agreement, the Company is obligated to use commercially reasonable efforts to research, discover, develop and market licensed products for commercial sale in the licensed territory, and to comply with certain obligations to meet specified development and funding milestones within defined time periods. Columbia University retains the right to conduct, and grant third parties the right to conduct, non-clinical academic research using the licensed technology; provided that such research is not funded by a commercial entity or for-profit entity or results in rights granted to a commercial or for-profit entity. As consideration for entering into the 2019 Columbia Agreement, the Company made a nominal upfront payment to Columbia University. The Company will be required to make further payments to Columbia University of up to an aggregate of $1.3 million for the achievement of specified development and regulatory milestones, and up to an aggregate of $1.0 million for the achievement of a specified level of aggregate annual net sales, in each case in connection with products covered by the 2019 Columbia Agreement. The Company will also be required to pay tiered royalties to Columbia University in the low- to mid-single digit percentages on the Company’s, its affiliates’ and its sublicensees’ net sales of licensed products, subject to specified offsets and reductions. In addition, the Company is required to make specified annual minimum royalty payments to Columbia University, which is contingent upon the approval of the licensed products, in the mid-six figures beginning on the tenth anniversary of the effective date of the 2019 Columbia Agreement. The Company has not granted any sublicenses under the 2019 Columbia Agreement. However, if the Company sublicenses the rights granted under the 2019 Columbia Agreement to one or more third parties, it will be required to pay Columbia University a portion of the net sublicensing revenue received from such third parties, at percentages between 10% and 50%, depending on the stage of development at the time such revenue is received from such third parties. The 2019 Columbia Agreement will terminate upon the expiration of all the Company’s royalty payment obligations in all countries. The Company may terminate the 2019 Columbia Agreement for convenience upon 90 days’ written notice to Columbia University. At its election, Columbia University may terminate the 2019 Columbia Agreement, or convert the licenses granted to the Company into non-exclusive, non-sublicensable licenses, in the case of (a) the Company’s uncured material breach upon 30 days’ written notice (which shall be extended to 90 days if the Company is diligently attempting to cure such material breach), (b) the Company’s failure to achieve the specified development and funding milestone events, or (c) the Company’s insolvency . In March 2019, and in connection with the 2016 Columbia Agreement, the Company entered into a research services agreement (the “2019 Columbia Research Agreement”) with Columbia University with the purpose of analyzing structural and functional changes in brain tissue in an animal model of galactosemia, and the effects of certain compounds whose intellectual property rights were licensed to the Company as part of the 2016 Columbia Agreement on any such structural and functional changes. The 2019 Columbia Research Agreement has a term of 12 months from its effective date; provided that the Company can terminate the 2019 Columbia Research Agreement without cause with at least 30 days’ prior written notice. The services covered by the 2019 Columbia Research Agreement will be performed by Columbia University in two parts consisting of six months. The decision to proceed with Part 2 of the 2019 Columbia Research Agreement shall be made solely by the Company and will be contingent on the success of the research performed in Part 1. In consideration for the services performed by Columbia University in Part 1, the Company will be required to pay $0.1 million to Columbia University for staffing, supplies and indirect costs. If the Company decides to continue the research defined in Part 2, the Company will be required to pay an additional $0.2 million to Columbia University. On October 3, 2019, and in connection with the 2019 Columbia Agreement, the Company entered into a research services agreement (the “PI3k Columbia Research Agreement” and collectively with the 2016 Columbia Agreement, 2019 Columbia Agreement and 2019 Columbia Research Agreement, the “Columbia Agreements”) with Columbia University with the purpose of analyzing PI3k inhibitors for the treatment of lymphoid malignancies. The research service agreement has a term of 18 months from is effective date; provided that the Company can terminate the research service agreement without cause with at least 30 days prior written notice. Midway through the study period, the Company and Columbia University will review the results of all completed and in progress research and determine whether the research will continue. In consideration for the services performed by Columbia University, the Company will be required to pay $0.4 million to Columbia University for staffing, supplies and indirect costs . During the years ended December 31, 2020 and 2019, the Company recorded $0.3 million and $0.1 million in research and development expense, respectively, and $0.1 million and $0.5 million, respectively, in general and administrative expense related to the Columbia Agreements. In aggregate, the Company has incurred $2.3 milli on in expense from the execution of the Columbia Agreements through December 31, 2020. As of December 31, 2020, the Company had $0.1 million due to Columbia University included in accrued expenses and $0 included in accounts payable. As of December 31, 2019, the Company had $0.1 million due to Columbia University included in accrued expenses and $0.1 million included in accounts payable. University of Miami 2020 Miami License Agreement On October 28, 2020, the Company entered into a license agreement with the University of Miami (the “2020 Miami License Agreement”) relating to certain technology that is co-owned by the University of Miami (UM), the University of Rochester (UR) and University College London (UCL). UM was granted an exclusive agency from UR and UCL to license each of their rights in the technology. Pursuant to the 2020 Miami License Agreement, UM, on behalf of itself and UR and UCL, granted us a royalty-bearing, sublicensable license that is exclusive with respect to certain patent applications and patents that may grant from the applications, and non-exclusive with respect to certain know-how, in each case to research, develop, make, have made, use, sell and import products for use in treating and/or detecting certain inherited neuropathies, in particular those caused by mutation in the sorbitol dehydrogenase (SORD) gene. The license grant is worldwide. Under the 2020 Miami License Agreement, the Company is obligated to use commercially reasonable efforts to develop, manufacture, market and sell licensed products in the licensed territory, and to comply with certain obligations to meet specified development milestones within defined time periods. UM retains for itself UR and UCL the right to use the licensed patent rights and licensed technology for their internal non-commercial educational, research and clinical patient care purposes, including in sponsored research and collaboration with commercial entities. As the technology licensed to us under the 2020 Miami License Agreement was developed as a result of a U.S. government grant, the licenses granted to us under the agreement are subject to the terms of such grant, and to standard rights of the U.S. government under the Bayh-Dole Act, including the grant to the government of a non-exclusive, worldwide, freedom to operate license under any patents, and the requirement, absent a waiver, to manufacture products substantially in the United States. Under the terms of the 2020 Miami License Agreement, the Company was obligated to pay UM an up-front non-refundable license fee of $1.1 million, and a second non-refundable license fee of $0.5 million due on the first anniversary of the date of the license. The Company will be required to make further payments to UM of up to an aggregate $2.2 million for the achievement of specified patenting and development milestones, and up to an aggregate of $4.1 million for achievement of late stage regulatory milestones. The Company will also be required to pay royalties ranging from 0.88% - 5% on the Company’s, the Company’s affiliates’ and the Company’s sublicensees’ net sales of licensed products. If the Company sublicenses the rights granted under the 2020 Miami License Agreement to one or more third parties, the Company will be required to pay to UM a portion of the non-royalty sublicensing revenue received from such third parties ranging from 15% – 25%. The 2020 Miami License Agreement terminates upon the expiration of all issued patents and filed patent applications or 10 years after the first commercial sale of the last product or process for which a royalty is due, unless earlier terminated. In addition, the 2020 Miami License Agreement may be terminated by the Company at any time upon 60 days prior written notice to UM, and may be terminated by either the Company or UM upon material breach of an obligation if action to cure the breach is not initiated within 60 days of receipt of written notice. The Company recorded $2.0 million and $36,000 in research and development expense and general and administrative expense, respectively, during the year-ended December 31, 2020. As of December 31, 2020, the Company had $1.6 million in accrued expenses. 2020 Miami Option Agreement On October 28, 2020, the Company entered into an option agreement with the University of Miami (the “2020 Miami Option Agreement”) concerning certain research activities and technology relating to SORD neuropathy that may be pursued and developed by UM. Under the 2020 Miami Option Agreement, if UM conducts such research activities, then UM is obligated to grant us certain option rights to access and use the research results and to obtain licenses to any associated patent rights upon us making specified payments to UM within specified time limits. If the Company elects to obtain option rights the Company will be required to make payments to UM in the low-six figures to the low-seven figures, depending upon the rights the Company elects to obtain, and the Company will be obligated to make certain milestone payments in the high-six figures to mid-seven figures if UM conducts and completes certain research activities within specified time periods and the Company elects to receive rights to use the results of that research. 2020 Miami Sponsored Research Agreement On December 14, 2020, the Company entered into a research agreement with the University of Miami (the “2020 Miami Research Agreement”), under which the University of Miami will conduct a research study relating to SORD neuropathy and deliver a final report on the study to the Company. The term of the research agreement is from December 14, 2020 through December 30, 2021. The consideration for the 2020 Miami Research Agreement was $0.3 million. As of December 31, 2020, the Company recorded $3,740 in Accrued Expenses in relation to the 2020 Miami Research Agreement.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2020
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	3. FAIR VALUE MEASUREMENTS The following tables summarize, as of December 31, 2020 and 2019, the Company's financial assets and liabilities that are measured at fair value on a recurring basis, according to the fair value hierarchy described in the significant accounting policies section. As of December 31, 2020 (in thousands) Level 1 Level 2 Level 3 Total Cash $ 6,691 $ — $ — $ 6,691 Money market funds 50,775 — — 50,775 Total cash and cash equivalents $ 57,466 $ — $ — $ 57,466 U.S. government agency debt securities — 39,363 — 39,363 Total marketable securities $ — $ 39,363 $ — $ 39,363 Total financial assets measured at fair value on a recurring basis $ 57,466 $ 39,363 $ — $ 96,829 As of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Total Cash $ 18,783 $ — $ — $ 18,783 Money market funds 67 — — 67 Total cash and cash equivalents $ 18,850 $ — $ — $ 18,850 Commercial paper and corporate bonds — 7,520 — 7,520 U.S. government agency debt securities — 12,484 — 12,484 Total marketable securities $ — $ 20,004 $ — $ 20,004 Total financial assets measured at fair value on a recurring basis $ 18,850 $ 20,004 $ — $ 38,854 Investments in certificate of deposits, corporate bonds, and U.S. government agency debt securities have been classified as Level 2 as they are valued using quoted prices in less active markets or other directly or indirectly observable inputs. Fair values of corporate bonds and U.S. government agency debt securities were derived from a consensus or weighted average price based on input of market prices from multiple sources at each reporting period. With regard to commercial paper, all of the securities had high credit ratings and one year or less to maturity; therefore, fair value was derived from accretion of purchase price to face value over the term of maturity or quoted market prices for similar instruments if available. During the period ended December 31, 2020 and 2019, there were no transfers of financial assets between Level 1 and Level 2.

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2020
INVESTMENTS
INVESTMENTS	4. INVESTMENTS Marketable Securities Marketable securities, which the Company classifies as available-for-sale securities, primarily consist of high quality commercial paper, corporate bonds, and U.S. government debt obligations. Marketable securities with remaining effective maturities of twelve months or less from the balance sheet date are classified as short-term; otherwise, they are classified as long-term on the balance sheets. The following tables provide the Company’s marketable securities by security type (in thousands): As of December 31, 2020 As of December 31, 2019 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated (in thousands) Cost Gains Losses Fair Value Cost Gains Losses Fair Value Commercial paper, corporate bonds, and CDs with original maturity < 1 year $ — $ 0 $ — $ 0 $ 7,540 $ — $ (20) $ 7,520 US government agency debt security 39,475 11 (123) 39,363 12,466 19 (1) 12,484 Total $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004 The Company adopted ASU No. 2016-13, “Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” on January 1, 2020 and applied the new modified credit impairment guidance related to available-for-sale debt securities prospectively. Under the new guidance, at each reporting date, entities must evaluate their individual available-for-sale debt securities that are in an unrealized loss position and determine whether the decline in fair value below the amortized cost basis is from a credit loss or other factors. The amount of the decline related to credit losses is recorded as a credit loss expense in earnings with a corresponding allowance for credit losses and the amount of decline not related to credit losses are recorded through other comprehensive income, net of tax. As of December 31, 2020, our investment portfolio reported an unrealized loss of $0.1 million. Based on our evaluations, the Company determined that a credit loss allowance is not required since the decline was not related to underlying credit issues of the counterparties. The counterparties to these investments have high credit quality with investment grade ratings of at least AA + as of December 31, 2020, along with a history of no defaults. No single investment in the corporate portfolio had an individually material unrealized loss and in the aggregate. The total amount of unrealized losses of $0.1 million as of December 31, 2020 was only 0.25% of the total amortized costs basis of the investment portfolio. In addition, the Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost bases. Accordingly, based on the foregoing evaluation, the Company did not record any credit losses during the year ended December 31, 2020 and the entire amount of the decline in fair value below the amortized cost basis was recorded as an unrealized loss, net of tax, in other comprehensive loss in the Statements of Comprehensive Loss. Unrealized gains are also reflected, net of tax, as other comprehensive income (loss) in the Statements of Comprehensive Loss. Contractual maturities of the Company’s marketable securities are summarized as follows (in thousands): As of December 31, 2020 As of December 31, 2019 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated (in thousands) Cost Gains Losses Fair Value Cost Gains Losses Fair Value Due in one year or less $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004 Due in one through two years — — — — — — — — Total $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004 At December 31, 2020, the Company had $11,000 of gross unrealized gains and $0.1 million of gross unrealized losses primarily due to fluctuations in the fair value of certain U.S. government agency debt securities. During the year ended December 31, 2020, the Company recorded gross realized losses of $0.1 million and gross realized gains of $50,000 from the sale of marketable securities. The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of December 31, 2020 are as follows: As of December 31, 2020 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized Estimated Unrealized Estimated Unrealized Estimated (in thousands) Losses Fair Value Losses Fair Value Losses Fair Value US government agency debt security (123) 14,073 — — (123) 14,073 Total $ (123) $ 14,073 $ — $ — $ (123) $ 14,073 The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of December 31, 2019 are as follows: As of December 31, 2019 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized Estimated Unrealized Estimated Unrealized Estimated (in thousands) Losses Fair Value Losses Fair Value Losses Fair Value Commercial paper and corporate bonds $ (20) $ 7,520 $ — $ — $ (20) $ 7,520 US government agency debt security (1) 3,497 — — (1) 3,497 Total $ (21) $ 11,017 $ — $ — $ (21) $ 11,017

PREPAID EXPENSES AND OTHER CURR

PREPAID EXPENSES AND OTHER CURRENT ASSETS	12 Months Ended
	Dec. 31, 2020
PREPAID EXPENSES AND OTHER CURRENT ASSETS
PREPAID EXPENSES AND OTHER CURRENT ASSETS	5. PREPAID EXPENSE AND OTHER CURRENT ASSETS Prepaid expenses and other current assets consisted of the following (in thousands): December 31, December 31, (in thousands) 2020 2019 Prepaid research and development expenses 2,349 5,872 Insurance Premium Asset 1,463 — Prepaid rent expenses 108 142 Prepaid insurance expenses 91 1,196 Prepaid Commercial and Patient Advocacy 968 — Research and Development Tax Credit Receivable 500 — Interest Receivable 5 — Other prepaid expenses and current assets 280 91 Total prepaid expenses & other current assets $ 5,764 $ 7,301

ACCRUED EXPENSES AND OTHER CURR

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES	12 Months Ended
	Dec. 31, 2020
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES	6. ACCRUED EXPENSE AND OTHER CURRENT LIABILITIES Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, (in thousands) 2020 2019 Accrued pre-clinical and clinical expenses $ 13,742 $ 4,287 Short-term insurance financing note 1,074 — Accrued professional fees 511 345 Accrued compensation and benefits 2,103 — Accrued commercial expenses 502 — Accrued patent expenses 1,704 54 Other 553 264 Total accrued expenses & other current liabilities $ 20,189 $ 4,950

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION	12 Months Ended
	Dec. 31, 2020
STOCK BASED COMPENSATION
STOCK BASED COMPENSATION	7. STOCK‑BASED COMPENSATION Equity Incentive Plans In May 2019, the Company's board of directors (the "Board") adopted its 2019 Equity Incentive Plan ("2019 Plan"), which was subsequently approved by its stockholders and became effective on May 13, 2019. As a result, no additional awards under the Company's 2016 Equity Incentive Plan, as amended (the "2016 Plan") will be granted and all outstanding stock awards granted under the 2016 Plan that are repurchased, forfeited, expired or are cancelled will become available for grant under the 2019 Plan in accordance with its terms. The 2016 Plan will continue to govern outstanding equity awards granted thereunder. The 2019 Plan provides for the issuance of incentive stock options ("ISOs") to employees, and for the grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, performance cash awards and other forms of stock awards to the Company's employees, officers and directors, as well as non- employees, consultants and affiliates to the Company. Under the terms of the 2019 Plan, stock options may not be granted at an exercise price less than fair market value of the Company's common stock on the date of the grant. The 2019 Plan will be administered by the Compensation Committee of the Company's Board. Initially, subject to adjustments as provided in the 2019 Plan, the maximum number of the Company's common stock that may be issued under the 2019 Plan is 4,530,000 shares, which is the sum of (i) 1,618,841 new shares, plus (ii) the number of shares (not to exceed 2,911,159 shares) that remained available for the issuance of awards under the 2016 Plan, at the time the 2019 Plan became effective, and (iii) any shares subject to outstanding stock options or other stock awards granted under the 2016 Plan that are forfeited, expired, or reacquired. The 2019 Plan provides that the number of shares reserved and available for issuance under the 2019 Plan will automatically increase each January 1, beginning on January 1, 2020, by 5% of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Board. Subject to certain changes in capitalization of the Company, the aggregate maximum number of shares of common stock that may be issued pursuant to the exercise of ISOs shall be equal to 13,000,000 shares of common stock. Stock options awarded under the 2019 Plan expire 10 years after grant and typically vest over four years. As of December 31, 2020, there were no shares of common stock available for issuance under the 2019 Plan. On January 1, 2021 there were 1,124,683 shares that became issuable for future grants subject to the adjustments provided in the 2019 Plan. Stock-Based Compensation Expense Total stock‑based compensation expense recorded for employees, directors and non‑employees (in thousands): Year Ended December 31, (in thousands) 2020 2019 Research and development $ $ 2,580 $ 2,762 General and administrative 5,446 3,409 Total stock-based compensation expense $ 8,026 $ 6,171 Stock Option Activity During the year ended December 31, 2020, and 2019 the Company granted options to purchase 1,105,604 and 2,969,945 shares of common stock, respectively. The weighted‑average fair value of options granted during the year ended December 31, 2020 and 2019 was $18.84 per share and $5.68 per share, respectively. As of December 31, 2020 and 2019, the total unrecognized stock‑based compensation balance for unvested options was $25.2 million and $12.5 million, respectively, which is expected to be recognized over 2.6 and 1.7 years, respectively. The total fair value of options vested during the year ended December 31, 2020 and 2019 was $0.5 million and approximately $3.5, million respectively. The following table summarizes the information about options outstanding at December 31, 2020 (in thousands, except share and per share data): Weighted-Average Weighted- Remaining Aggregate Options Average Contractual Intrinsic (in thousands, except for share data) Outstanding Exercise Price Term (in years) Value Outstanding at December 31, 2019 4,079,888 $ 5.11 8.26 $ 82,327 Options granted 1,105,604 30.73 Options exercised (522,160) 3.48 19,037 Forfeited (133,657) 12.45 Expired — Outstanding at December 31, 2020 4,529,675 $ 12.87 8.49 $ 51,103 Exercisable at December 31, 2020 2,226,178 $ 5.69 7.94 $ 36,903 Nonvested at December 31, 2020 2,303,497 $ 19.80 9.01 $ 14,200 In April 2019, the Company modified certain stock options with service-based conditions that were originally granted under the 2016 Plan. The modification resulted in the vesting for these options to accelerate. There was no incremental stock-based compensation expense as a result of this modification as the fair-value-based measures of the modified awards immediately after the modification were less than the fair-value-based measures of the original awards immediately before the modification. Valuation of Stock Options Granted to Employees that Contain Service Conditions Only The fair value of each option award granted with service-based vesting is estimated on the date of the grant using the Black-Scholes option valuation model based on the weighted average assumptions noted in the table below for those options granted in the years ended December 31, 2020 and 2019. Year Ended December 31, 2020 2019 Expected term (in years) 6.1 5.7 Volatility 69.70 % 72.54 % Risk-free interest rate 0.51 % 2.17 % Dividend yield 0.00 % 0.00 % Stock Options Granted to Employees that Contain Service, Performance and Market Conditions Included in the stock options granted during the year ended December 31, 2019 were 159,501 stock options that contain service-, performance- and market-based vesting conditions granted to the Company's interim Chief Financial Officer ("CFO") with a fair value at the grant date of $0.5 million, valued using the Monte-Carlo simulation model. The derived service period, calculated using the Monte-Carlo simulation model, ranged from one day to three years. The assumptions used in the Monte-Carlo simulation model were as follows: Time to expiration (in years) 10.0 Volatility 68.54 % Risk-free interest rate 2.64 % Dividend yield 0.00 % Cost of equity 24.00 % Fair value of underlying common stock (as of valuation date) $ 5.85 The compensation expense for these awards is recognized over the derived service period, or, if earlier, until the vesting condition is met. The condition for the performance-based stock options was based on the Company's completion of its IPO and the condition for the market-based stock options was based on the future price of the Company's common stock trading at or above a specified threshold. During the year ended December 31, 2019, 79,778 of the stock options containing service-, and performance-based vesting conditions were vested following the satisfaction of service- and performance-based conditions. In May 2019, the Company entered into a severance agreement, effective on May 31, 2019 ("Termination Date"), with the interim CFO. As part of this severance arrangement and as of the Termination Date, the Company accelerated the vesting of 79,723 unvested options, which were originally granted to the former CFO under the 2016 Plan. As a result of this modification, the Company recorded stock-based compensation expense of $0.6 million included in general and administrative expense for the year ended December 31, 2019. The Company accounted for this modification as a Type III modification since, at the modification date, the expectation of the award vesting changed from improbable to probable. As a result, the stock-based compensation expense recognized was based on the modification-date fair value. As of December 31, 2020 all stock options containing service-, performance-, and market-based vesting conditions were vested. As of December 31, 2020, there were no outstanding stock options containing performance- and market-based vesting conditions. The Company recorded $0.7 million in stock-based compensation expense relating to these awards for the year ended December 31, 2019. Restricted Stock Unit Activity On March 9, 2020, the Board approved the grant of 36,464 restricted stock units (“RSUs”) to an employee of the Company, pursuant to the 2019 Equity Plan. One-fourth of the RSUs shall vest in four equal annual installments commencing one year after the date of grant, subject to the employee continuing to provide services through each such date. These shares were valued at $1.3 million, determined using price per share of $34.28, the closing price of the Company’s common stock on March 9, 2020, and will be amortized ratably over the term of the vesting periods of four years on a straight line basis. On June 4, 2020, the Board approved the grant of 108,662 RSUs to employees of the Company, pursuant to the 2019 Equity Plan. One-fourth of such RSUs vest in four equal annual installments commencing one year after the date of grant, subject to the respective employee continuing to provide services through each such date. These shares were valued at $4.8 million, determined using price per share of $44.02, the closing price of the Company’s common stock on June 4, 2020, and will be amortized ratably over the term of the vesting periods of four years on a straight line basis. On December 10, 2020, the Board approved the grant of 61,553 RSUs to employees of the Company, pursuant to the 2019 Equity Plan. One-fourth of such RSUs vest in four equal annual installments commencing one year after the date of grant, subject to the respective employee continuing to provide services through each such date. These shares were valued at $1.4 million, determined using price per share of $23.15, the closing price of the Company’s common stock on December 10, 2020, and will be amortized ratably over the term of the vesting periods of four years on a straight line basis. For the year ended December 31, 2020, amortization of stock compensation of RSUs amounted to $1.0 million. As of December 31, 2020, the unamortized compensation costs associated with non-vested restricted stock awards were $6.6 million with a weighted-average remaining amortization period of 3.4 years. The following table summarizes the information about restricted stock units outstanding at December 31, 2020 (in thousands, except share and per share data): Weighted-Average Aggregate Grant Date Intrinsic Value (in thousands, except for share data) Shares Fair Value As of December 31, 2020 Outstanding at December 31, 2019 — $ — Awarded 206,679 36.09 Released - — Forfeited (150) 44.02 Outstanding at December 31, 2020 206,529 $ 36.08 $ 4,546 Nonvested at December 31, 2020 206,529 $ 36.08 $ 4,546 Weighted Average Remaining Recognition Period (in years) 3.43 2019 Employee Stock Purchase Plan In May 2019, the Company’s Board and its stockholders approved the 2019 Employee Stock Purchase Plan (the “ESPP”), which became effective as of May 13, 2019. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the U.S. Internal Revenue Code of 1986, as amended. The number of shares of common stock initially reserved for issuance under the ESPP was 180,000 shares. The ESPP provides for an annual increase on the first day of each year beginning in 2020 and ending in 2029, in each case subject to the approval of the Board, equal to the lesser of (i) 1% of the shares of common stock outstanding on the last day of the calendar month before the date of the automatic increase and (ii) 360,000 shares; provided that prior to the date of any such increase, the Board may determine that such increase will be less than the amount set forth in clauses (i) and (ii). As of December 31, 2020, no shares of common stock had been issued under the ESPP. The first offering period has not yet been decided by the Board.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2020
STOCKHOLDERS’ EQUITY
STOCKHOLDERS’ EQUITY	8 . STOCKHOLDERS’ EQUITY As of December 31, 2020, and 2019, the authorized capital stock of the Company consists of 100,000,000 shares of common stock, par value $0.0001 per share and 10,000,000 shares of preferred stock, par value $0.0001 per share. Common Stock Voting The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of the stockholders. There is no cumulative voting. Equity Distribution Agreement In June 2020, the Company entered into the Equity Distribution Agreement with Goldman to sell shares of the Company’s common stock, from time to time, having and aggregate offering price of $100.0 million. The issuance and sale of shares of common stock by us pursuant to the Equity Distribution Agreement is deemed an “at-the-market” offering under the Securities Act of 1933, as amended, or the Securities Act. Goldman is entitled to compensation for its services equal to up to 3.0% of the gross offering proceeds of all shares of our common stock sold through it as a sales agent pursuant to the Equity Distribution Agreement. As of December 31, 2020, the Company has received no proceeds from the sale of shares of common stock pursuant to the Equity Distribution Agreement.

WARRANTS

WARRANTS	12 Months Ended
	Dec. 31, 2020
WARRANTS
WARRANTS	9. WARRANTS Warrants Issued with Series A Preferred Stock On January 26, 2017, in connection with the sale and issuance of the Series A Preferred Stock, the Company issued equity‑classified warrants to purchase 309,389 shares of common stock (the “2017 Warrants”), valued at $0.2 million, and included in the issuance costs of the Series A Preferred Stock. The warrants vested immediately and have an exercise price of $2.49 per share and expire on March 13, 2027. The fair value of warrants issued is estimated using the Black‑Scholes option pricing model with the following assumptions for the 2017 Warrants. Contractual term (in years) 10.0 Volatility 74.48 % Risk-free interest rate 3.20 % Dividend yield 0.00 % On December 5, 2019, an optionholder exercised 20,000 options in a cashless exercise at net, and the Company issued 17,026 shares of common stock. On February 21, 2020, two warrantholders exercised 185,634 options in a cashless exercise at net, and the Company issued 176,092 shares of common stock. On February 24, 2020, a warrantholder exercised 72,818 options in a cashless exercise at net, and the Company issued 69,094 shares of common stock. Warrants Issued with the 2018 Notes On January 18, 2018, the Company entered into a placement agent agreement through which it became obligated to issue common stock warrants in connection with the issuance of the Company’s convertible promissory notes issued on February 5, 2018 (the “2018 Notes”). The obligation to issue the 2018 Notes Warrants was recorded as a liability at its fair value (see Note 3), which was initially $0.1 million, and was included in the issuance costs of the 2018 Notes. On November 5, 2018, in connection with the extinguishment of the 2018 Notes into shares of Series B Preferred Stock, the Company issued the 2018 Notes Warrants, which were equity‑classified warrants upon issuance, to purchase 76,847 shares of common stock, valued at $0.3 million. The 2018 Notes Warrants vested immediately upon issuance and have an exercise price of $6.59 per share and expire on November 4, 2028. On February 24, 2020, a warrantholder exercised 386 options in a cashless exercise at net, and the Company issued 333 shares of common stock. On June 24, 2020, a warrantholder exercised 20,331 options in a cashless exercise at net, and the Company issued 17,369 shares of common stock. Warrants Issued with Series B Preferred Stock In November and December 2018, in connection with the sale and issuance of the Series B Preferred Stock, the Company was obligated to issue equity‑classified warrants to purchase 72,261 shares of common stock (collectively the “2018 Warrants”), valued in the aggregate at $0.2 million, which was included in the issuance costs for the Series B Preferred Stock. The warrants vest immediately upon issuance, have an exercise price of $8.24 per share and expire 10 years from the date of issuance. The fair value of the 2018 Warrants is estimated using the Black‑Scholes option pricing model with the following assumptions: Contractual term (in years) 10.0 Volatility 73.22 % Risk-free interest rate 2.70 % Dividend yield 0.00 % In February 2019, in connection with the sale and issuance of the Series B Preferred Stock, the Company was obligated to issue warrants to purchase 23,867 shares of common stock (collectively the “2019 Warrants”), valued in the aggregate at $0.1 million, which was included in the issuance costs for the Series B Preferred Stock. The warrants vest immediately upon issuance, have an exercise price of $8.24 per share and expire 10 years from the date of issuance. The fair value of the 2019 Warrants was estimated using the Black-Scholes option pricing model with the following assumptions: Contractual term (in years) 10.0 Volatility 73.22 % Risk-free interest rate 2.70 % Dividend yield 0.00 % The inputs utilized by management to value the warrants are highly subjective. The assumptions used in calculating the fair value of the warrants represent the Company’s best estimates, but these estimates involve inherent uncertainties and the application of management judgment. As a result, if factors change and the Company uses different assumptions, the fair value of the warrants may be materially different in the future. On January 14, 2020, a warrantholder exercised 220 options in a cashless exercise at net, and the Company issued 146 shares of common stock. On February 24, 2020, a warrantholder exercised 5,193 options in a cashless exercise at net, and the Company issued 4,313 shares of common stock. On June 24, 2020, a warrantholder exercised 24,309 options in a cashless exercise at net, and the Company issued 19,882 shares of common stock. A summary of the Company’s outstanding common stock warrants as of December 31, 2020 is as follows: Warrants Outstanding as of December 31, 2019 462,364 Warrants granted and issued — Warrants exercised (308,891) Warrants exchanged — Balance as of December 31, 2020 153,473

LEASES

LEASES	12 Months Ended
	Dec. 31, 2020
LEASES
LEASES	10. LEASES The following table summarizes our lease assets and liabilities as of December 31, 2020 and 2019: Operating December 31, December 31, ROU Assets and Liabilities Balance Sheet Location 2020 2019 ROU - Asset Right-of-use assets $ 1,712 $ 2,035 Lease liabilities (current) Operating lease liabilities, current 406 356 Lease liabilities (non-current) Operating lease liabilities, non-current 1,332 1,683 The following table summarizes our lease related costs for the twelve months ended December 31, 2020 and 2019: Operating (in thousands) Lease Cost Statement of Operations Location 2020 2019 Operating Lease Cost General and administrative $ 487 $ 81 Total Lease Cost $ 487 $ 81 Average lease terms and discount rates for the Company’s operating leases were as follows: Year Ended Year Ended December 31, December 31, Other Information 2020 2019 Weighted-average remaining lease term Operating leases 3.8 4.8 Weighted-average discount rate Operating leases The following table summarizes the maturities of lease liabilities as of December 31, 2020: Operating Year (in thousands) 2021 $ 494 2022 507 2023 515 2024 424 Thereafter — Total lease payments 1,940 Less: interest 202 Total lease liabilities $ 1,738

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
INCOME TAXES	11. INCOME TAXES The Company’s current tax provision for the years ended December 31, 2020 and 2019 is $0 and $0, respectively. The Company’s deferred tax provision for the years ended December 31, 2020 and 2019 is $0 and $0, respectively. Deferred income tax assets and liabilities consist of the following (in thousands): Year ended December 31, 2020 2019 Deferred Tax Assets Operating Lease Liability $ 541 $ 706 Stock-based compensation 3,788 1,582 License fee 630 22 Net operating loss carryforwards 49,094 19,937 Research and development tax credits 9,037 — Other 689 — Total Deferred Tax Assets $ 63,779 $ 22,247 Valuation Allowance $ (63,246) $ (21,542) Net Deferred Tax Assets $ 533 $ 705 Deferred Tax Liabilities Right of Use Asset (533) (705) Net Deferred Tax Liabilities $ (533) $ (705) Net deferred tax asset (liability) $ — $ — Deferred tax assets result primarily from unutilized net operating losses, stock-based compensation, operating lease liability, research and development tax credits, and timing differences as a result of the Company reporting its income tax returns. As of December 31, 2020, the Company had approximately $157.1 million of federal operating losses (“NOLs”) carried forward. Of this amount, approximately $3.3 million will begin to expire in 2037 and approximately $153.8 million are carried forward indefinitely. The Company had approximately $158 million in New York State and New York City net operating loss carryforwards available to offset future taxable income. As of December 31, 2020, the Company had federal research tax credits (R&D) of approximately $3.7 million which may be used to offset future tax liabilities. Additionally, the Company had a federal orphan drug credit (ODC) related to qualifying research of $5.3 million. These tax credit carryforwards will begin to expire at various times beginning in 2037 for federal purposes. The NOL, R&D and ODC credits carry forwards are subject to review and possible adjustment by the U.S. and state tax authorities. NOL carry forwards and credit carry forwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders, as defined under Sections 382 and 383 Internal Revenue Code. This could limit the amount of NOLs and credits that the Company can utilize annually to offset future taxable income or tax liabilities. As of December 31, 2020, the Company has not performed such an analysis. Subsequent ownership changes and proposed future changes to tax rules in respect of the utilization of losses carried forward may further affect the limitation in future years. In assessing the realizability of the Company’s deferred tax assets, management considers whether or not it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income. The Company’s assessment is based on the weight of available evidence, including cumulative losses since inception and expected future losses and, as such, the Company does not believe it is more likely than not that the deferred tax assets will be realized. Accordingly, a full valuation allowance has been established and no deferred tax assets and related tax benefit have been recognized in the accompanying financial statements. At December 31, 2020 and 2019, the Company recorded valuation allowances of $63.2 million and $21.5 million, respectively. The increase in valuation allowance is primarily driven by additional net operating loss. The Company files its income tax returns in the United States, New York State, New York City, and New Jersey. All years remain subject to examination for federal and state purpose. The U.S. federal statutory corporate tax rate reconciles to the Company’s effective tax rate for the years ended December 31, 2020 and 2019: Year Ended December 31, 2020 2019 Federal statutory rate 21.0 % 21.0 % State and local taxes net of federal tax benefit 9.9 13.2 Credits 9.6 0.0 Permanent Differences 3.9 (33.4) Change in valuation allowance (44.3) (0.7) Other (0.1) (0.1) Total % % On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted in the United States. The CARES Act provides numerous tax provisions and other stimulus measures, including temporary changes regarding the prior and future utilization of net operating losses, temporary suspension of certain payment requirements for the employer portion of Social Security taxes, technical corrections from prior tax legislation for tax depreciation of certain qualified improvement property, and the creation of certain refundable employee retention credits. The Company evaluated the provisions of the CARES Act and does not anticipate the associated impacts, if any, will have a material effect on the Company’s provision for income taxes for the year ended December 31, 2020.

BENEFIT PLANS

BENEFIT PLANS	12 Months Ended
	Dec. 31, 2020
BENEFIT PLANS
BENEFIT PLANS	12. BENEFIT PLANS The Company established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code in 2018. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre‑tax basis. Matching contributions to the plan may be made at the discretion of the Company’s Board. The Company made approximately $0.1 million and $69,000 in matching contributions to the plan during the year ended December 31, 2020 and 2019, respectively.

NET LOSS PER COMMON SHARE

NET LOSS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2020
NET LOSS PER COMMON SHARE
NET LOSS PER COMMON SHARE	13. NET LOSS PER COMMON SHARE Basic net loss per common share is computed by dividing the net loss available to common stockholders by the weighted‑average number of shares of common stock outstanding during the period. Diluted net loss per common share is computed by giving the effect of all potential shares of common stock, including stock options, preferred shares, warrants and instruments convertible into common stock, to the extent dilutive. Basic and diluted net loss per common share was the same for the years ended December 2020 and 2019, as the inclusion of all potential common shares outstanding would have been anti‑dilutive. The following table sets forth the computation of basic and diluted net loss per common share (in thousands, except share and per share data): Years Ended December 31, (in thousands, except for share data) 2020 2019 Numerator: Net loss $ (93,961) $ (45,513) Denominator: Weighted-average common stock outstanding 21,966,326 12,831,221 Net loss per share attributable to common stockholders - basic and diluted $ (4.28) $ (3.55) The Company’s potentially dilutive securities, which include restricted stock units, stock options and warrants, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted‑average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at December 31, 2020 and 2019, from the computation of diluted net loss per share attributable to common stockholders because including them would have had an anti‑dilutive effect: As of December 31, 2020 2019 Options to purchase common stock 4,529,675 4,079,888 Restricted stock units 206,529 — Warrants to purchase common stock 153,473 462,364

RELATED PARTIES

RELATED PARTIES	12 Months Ended
	Dec. 31, 2020
RELATED PARTIES
RELATED PARTIES	14. RELATED PARTIES In December 2018, the Company entered into an agreement (the “LaunchLabs Agreement”) with ARE‑LaunchLabs NYC LLC (“Alexandria LaunchLabs”), a subsidiary of Alexandria Real Estate Equities, Inc. for use of specified premises within the Alexandria LaunchLabs space on a month-to-month basis. A member of the Company’s board of directors is the founder and executive chairman of Alexandria Real Estate Equities, Inc. During the years ended December 31, 2020 and 2019, the Company made payments to Alexandria LaunchLabs of approximately $89,000 and $85,000, respectively under the LaunchLabs Agreement, which was recognized in research and development expenses. As of December 31, 2020, there were no amounts due to Alexandria LaunchLabs under the LaunchLabs Agreement.

SUBSEQUENT EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2020
SUBSEQUENT EVENT
SUBSEQUENT EVENTS	15. SUBSEQUENT EVENTS On February 17, 2021, the Company completed the February Offering, consisting of 3,450,000 shares of common stock, including the exercise in full of the underwriters’ option to purchase 450,000 additional shares of common stock, which option closed on February 19, 2021. The shares were offered at a price to the public of $23.00 per share, resulting in aggregate net proceeds of approximately $74.3 million , after deducting underwriting discounts and commissions and estimated offering expenses.

ORGANIZATION AND SUMMARY OF S_2

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2020
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Liquidity	Liquidity The Company has incurred, and expects to continue to incur, significant operating losses and negative cash flows for at least the next several years as it continues to develop its drug candidates. To date, the Company has not generated any revenue, and it does not expect to generate revenue unless and until it successfully completes development and obtains regulatory approval for one of its product candidates. Management believes that the Company’s existing cash, together with the net proceeds from the S econdary Public Offering and the February Offering, will allow the Company to continue its operations for at least 12 months from the issuance date of these financial statements. If the Company is unable to obtain additional funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.
Risk and Uncertainties	Risks and Uncertainties The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and reliance on third party manufacturers.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. 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 financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are reported on a recurring basis 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 and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all short‑term, highly liquid investments, with an original maturity of three months or less, to be cash equivalents. The Company maintains its cash in bank deposit accounts which, at times, may exceed federally insured limits. The Company has not experienced any losses in these accounts and does not believe it is exposed to any significant credit risk on cash and cash equivalents.
Investments	Investments The Company has investments in marketable debt securities. The Company determines the appropriate classification of its investments at the date of purchase and reevaluate the classifications at the balance sheet date. Marketable debt securities with maturities of 12 months or less are classified as short-term. Marketable debt securities with maturities greater than 12 months are classified as long-term. The Company’s marketable securities are accounted for as available for sale (“AFS”). AFS securities are reported at fair value. Unrealized gains and losses, after applicable income taxes, are reported in accumulated other comprehensive income/(loss). Realized gains or losses on the sale of marketable securities are determined using the specific identification method and are recorded as a component of other income (expense), net. The Company conducts an other-than-temporary impairment (“OTTI”) analysis on a quarterly basis or more often if a potential loss-triggering event occurs. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and whether the Company intends to sell. For AFS securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis and (ii) the amortized cost basis cannot be recovered as a result of credit losses. The Company adopted ASU No. 2016-13, “Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” on January 1, 2020 and applied the new modified credit impairment guidance related to available-for-sale debt securities prospectively. Under the new guidance, at each reporting date, entities must evaluate their individual available-for-sale debt securities that are in an unrealized loss position and determine whether the decline in fair value below the amortized cost basis from a credit loss or other factors. The amount of the decline related to credit losses is recorded as a credit loss expense in earnings with a corresponding allowance for credit losses and the amount of decline not related to credit losses are recorded through other comprehensive income, net of tax.
Leases	Leases At the inception of an arrangement, the Company determines if an arrangement is, or contains, a lease based on the unique facts and circumstances present in that arrangement. Lease classification, recognition, and measurement are then determined at the lease commencement date. For arrangements that contain a lease the Company (i) identifies lease and non-lease components, (ii) determines the consideration in the contract, (iii) determines whether the lease is an operating or financing lease; and (iv) recognizes lease ROU assets and liabilities. Lease liabilities and their corresponding ROU assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable and as such, the Company uses its incremental borrowing rate based on the information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. Most leases include options to renew and, or, terminate the lease, which can impact the lease term. The exercise of these options is at the Company’s discretion and the Company does not include any of these options within the expected lease term as the Company is not reasonably certain it will exercise these options. The Company has elected to combine lease components (for example fixed payments including rent) with non-lease components (for example, non-dedicated parking and common-area maintenance costs) on our real estate asset classes. Fixed, or in substance fixed, lease payments on operating leases are recognized over the expected term of the lease on a straight-line basis. Fixed lease expense on operating leases is recognized within operating expenses within the statements of operations. The Company has operating leases for our corporate offices. The Company has elected the short-term lease exemption and, therefore, do not recognize a ROU asset or corresponding liability for lease arrangements with an original term of 12 months or less. Leasehold improvements and assets under financing lease arrangements are amortized over the lesser of the asset’s estimated useful life or the term of the respective lease. Maintenance costs are expensed as incurred. Operating leases are included in operating lease right-of-use asset, current portion of operating lease liabilities, and noncurrent portion of operating lease liabilities in the balance sheet as of December 31, 2020 and 2019.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in the statement of stockholders’ (deficit) equity as a reduction of proceeds generated as a result of the offering. Should a planned equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statement of operations. Upon closing the IPO in May 2019, $2.6 million in deferred offering costs were reclassified from prepaid and other current assets and recorded against the IPO proceeds reducing additional paid-in capital. As of December 31, 2020 and 2019, the Company did not have any deferred offering costs recorded in prepaid and other current assets.
Common Stock Valuation	Common Stock Valuation For all periods prior to the IPO, the Company utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately‑Held Company Equity Securities Issued as Compensation (the “Practice Aid”), to estimate the fair value of its common stock. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to the Company’s common stock at the time of, and the likelihood of, achieving a liquidity event, such as an IPO or sale. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
Convertible Preferred Stock	Convertible Preferred Stock For all periods prior to the IPO, the Company recorded shares of its convertible preferred stock at their respective fair values on the dates of issuance less issuance costs. The Company classified shares of its convertible preferred stock outside of stockholders’ deficit when the redemption of such units or shares is outside the Company’s control. The Company did not adjust the carrying values of the convertible preferred units or convertible preferred stock to the liquidation preferences of such units or shares until such time as a deemed liquidation event is probable of occurring.
Research and Development	Research and Development The Company expenses all costs incurred in performing research and development activities. Research and development expenses include salaries and other related costs, materials and supplies, preclinical expenses, manufacturing expenses, contract services and other outside expenses. As part of the process of preparing the financial statements, the Company is required to estimate their accrued research and development expenses. The Company makes estimates of the accrued expenses as of each balance sheet date in the financial statements based on facts and circumstances known at that time. In addition, there may be instances in which payments made to the Company’s vendors will exceed the level of services provided and result in a prepayment of the expense in which case such amounts are reflected as prepaid expenses and other current assets. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts the accrual or the amount of prepaid expenses accordingly. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized in prepaid expenses and other current assets. The capitalized amounts are expensed as the related goods are delivered or the services are performed. Research and development costs also include costs incurred in connection with certain licensing arrangements. Before a compound receives regulatory approval, the Company records upfront and milestone payments made to third parties under licensing arrangements as expense. Upfront payments are recorded when incurred, and milestone payments are recorded when the specific milestone has been achieved. Once a compound receives regulatory approval, the Company will record any milestone payments in identifiable intangible assets, less accumulated amortization and, unless the asset is determined to have an indefinite life, the Company will amortize the payments on a straight-line basis over the remaining agreement term or the expected product life cycle, whichever is shorter.
General and Administrative	General and Administrative General and administrative expenses consist primarily of salaries and other related costs, including stock‑based compensation, for personnel in the Company’s executive and finance functions. General and administrative expenses also include professional fees for legal, accounting, auditing, tax and consulting services; travel expenses; and facility‑related expenses, which include allocated expenses for rent and maintenance of facilities and other operating costs. Commercial expenses consist of payroll expense for commercial personnel, as well as marketing, market research, market access, and other focused investments to support launch of drug candidates, generate evidence of commercial potential and value proposition, and maximize potential business development deal leverage. Commercial expenses are included in general and administrative expenses.
Stock Based Compensation–Restricted Stock Units	Stock‑Based Compensation The Company accounts for its stock‑based compensation as expense in the statements of operations based on the awards’ grant date fair values. The Company accounts for forfeitures as they occur by reversing any expense recognized for unvested awards. The Company estimates the fair value of options granted using the Black‑Scholes option pricing model. The Black‑Scholes option pricing model requires inputs based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of the award, (c) the risk‑free interest rate and (d) expected dividends. Due to the lack of a public market for the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The computation of expected volatility is based on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. The Company uses the simplified method as allowed by the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin (“SAB”) No. 107, Share‑Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The fair value of stock‑based payments is recognized as expense over the requisite service period which is generally the vesting period. Stock-Based Compensation–Restricted Stock Units The Company accounts for restricted stock units in accordance with the authoritative guidance for stock-based compensation. The fair value of restricted stock units is measured at the grant date based on the closing market price of the Company’s common stock on the date of grant, and is recognized as expense on a straight-line basis over the period of vesting. Forfeitures are recognized as a reduction of stock-based compensation expense as they occur.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities at currently enacted tax rates. These temporary differences primarily relate to net operating loss carryforwards available to offset future taxable income. Valuation allowances are established, if necessary, to reduce a deferred tax asset to the amount that will more likely than not be realized. The Company recognizes tax liabilities from an uncertain tax position only if it is more likely than not that the tax position will not be sustained upon examination by the taxing authorities, based on the technical merits of the tax position. There are no uncertain tax positions that have been recognized in the accompanying financial statements. The Company is required to file tax returns in the U.S. federal jurisdiction and in the state of New York. The Company’s policy is to recognize interest and penalties related to uncertain tax benefits, if any, as part of income tax expense. No such interest and penalties have been accrued as of December 31, 2020 and 2019.
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing net loss available to common stockholders by the weighted‑average common stock outstanding. Diluted net loss per share is calculated similarly, except that it includes the dilutive effect of the assumed exercise of securities, including outstanding warrants and the effect of shares issuable under the Company’s stock‑based compensation plan, if such effect is dilutive.
Segment Information	Segment Information Operating segments are defined as components of an enterprise for which separate discrete information is available for evaluation by the chief operating decision‑maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision‑maker, the Company’s chief executive officer, views the Company’s operations and manages its business as a single operating segment, which is the business of discovering and developing its product candidates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (CECL) methodology. The measurement of expected credit losses under the CECL methodology applies to financial instruments measured at amortized cost, including loan receivables and held-to-maturity debt securities, off-balance sheet credit exposures and net investments in leases recognized by a lessor. ASC 326 also made changes to the accounting for available-for-sale debt securities, where credit losses are required to be presented as an allowance as opposed to a write-down. The FASB issued authoritative guidance that amends guidance on reporting credit losses for assets, including available-for-sale marketable securities and any other financial assets not excluded from the scope that have the contractual right to receive cash. For available-for-sale marketable securities, credit losses should be measured in a manner similar to current generally accepted accounting standards; however, ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , will require that credit losses be presented as an allowance rather than as a write-down. For available-for-sale debt securities in an unrealized loss position, the Company assesses whether a decline in fair value resulted from credit losses or other factors. Management considers the extent to which fair value is less than amortized cost, any changes to the credit rating of the security, and adverse conditions specifically related to the security. If the assessment indicates a credit loss exists, an allowance is recorded that is limited to the amount the amortized cost exceeds the fair value. Any impairment that is not recognized through the allowance for credit loss is recognized in other comprehensive income. The Company adopted ASC 326 using the modified retrospective method approach, where a cumulative-effect adjustment to credit loss allowance would be reflected in retained earnings. The adoption of this standard did not have an impact on the Company’s balance sheet as there were no credit losses identified. In August 2018, the FASB issued ASU No. 2018-13, “ Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement ,” which modifies the disclosure requirements on fair value measurements. The new guidance is effective for fiscal years beginning after December 15, 2019. Upon the effective date, certain provisions are to be applied prospectively, while others are to be applied retrospectively to all periods presented. The amendments eliminated certain disclosure requirements such as the elimination of disclosing the valuation process for Level 3 fair value measurements. Other amendments in the update did not impact the Company. The Company adopted the amendments on January 1, 2020 with no impact on our financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes. The new standard intended to simplify the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. The standard is effective for annual periods beginning after December 15, 2020 and interim periods within, with early adoption permitted. Adoption of the standard requires certain changes to primarily be made prospectively, with some changes to be made retrospectively. The Company adopted the amendment in January 2021, and expects it will have no impact on our financial statements.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
FAIR VALUE MEASUREMENTS
Schedule of financial assets or liabilities measured at fair value on a recurring basis	As of December 31, 2020 (in thousands) Level 1 Level 2 Level 3 Total Cash $ 6,691 $ — $ — $ 6,691 Money market funds 50,775 — — 50,775 Total cash and cash equivalents $ 57,466 $ — $ — $ 57,466 U.S. government agency debt securities — 39,363 — 39,363 Total marketable securities $ — $ 39,363 $ — $ 39,363 Total financial assets measured at fair value on a recurring basis $ 57,466 $ 39,363 $ — $ 96,829 As of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Total Cash $ 18,783 $ — $ — $ 18,783 Money market funds 67 — — 67 Total cash and cash equivalents $ 18,850 $ — $ — $ 18,850 Commercial paper and corporate bonds — 7,520 — 7,520 U.S. government agency debt securities — 12,484 — 12,484 Total marketable securities $ — $ 20,004 $ — $ 20,004 Total financial assets measured at fair value on a recurring basis $ 18,850 $ 20,004 $ — $ 38,854

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2020
INVESTMENTS
Schedule of marketable securities by security type	The following tables provide the Company’s marketable securities by security type (in thousands): As of December 31, 2020 As of December 31, 2019 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated (in thousands) Cost Gains Losses Fair Value Cost Gains Losses Fair Value Commercial paper, corporate bonds, and CDs with original maturity < 1 year $ — $ 0 $ — $ 0 $ 7,540 $ — $ (20) $ 7,520 US government agency debt security 39,475 11 (123) 39,363 12,466 19 (1) 12,484 Total $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004
Schedule of contractual maturities	Contractual maturities of the Company’s marketable securities are summarized as follows (in thousands): As of December 31, 2020 As of December 31, 2019 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated (in thousands) Cost Gains Losses Fair Value Cost Gains Losses Fair Value Due in one year or less $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004 Due in one through two years — — — — — — — — Total $ 39,475 $ 11 $ (123) $ 39,363 $ 20,006 $ 19 $ (21) $ 20,004
Unrealized Gain (Loss) on Investments	As of December 31, 2020 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized Estimated Unrealized Estimated Unrealized Estimated (in thousands) Losses Fair Value Losses Fair Value Losses Fair Value US government agency debt security (123) 14,073 — — (123) 14,073 Total $ (123) $ 14,073 $ — $ — $ (123) $ 14,073 As of December 31, 2019 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized Estimated Unrealized Estimated Unrealized Estimated (in thousands) Losses Fair Value Losses Fair Value Losses Fair Value Commercial paper and corporate bonds $ (20) $ 7,520 $ — $ — $ (20) $ 7,520 US government agency debt security (1) 3,497 — — (1) 3,497 Total $ (21) $ 11,017 $ — $ — $ (21) $ 11,017

PREPAID EXPENSES AND OTHER CU_2

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)	12 Months Ended
	Dec. 31, 2020
PREPAID EXPENSES AND OTHER CURRENT ASSETS
Summary of prepaid expenses and other current assets	Prepaid expenses and other current assets consisted of the following (in thousands): December 31, December 31, (in thousands) 2020 2019 Prepaid research and development expenses 2,349 5,872 Insurance Premium Asset 1,463 — Prepaid rent expenses 108 142 Prepaid insurance expenses 91 1,196 Prepaid Commercial and Patient Advocacy 968 — Research and Development Tax Credit Receivable 500 — Interest Receivable 5 — Other prepaid expenses and current assets 280 91 Total prepaid expenses & other current assets $ 5,764 $ 7,301

ACCRUED EXPENSES AND OTHER CU_2

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2020
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES
Summary of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, December 31, (in thousands) 2020 2019 Accrued pre-clinical and clinical expenses $ 13,742 $ 4,287 Short-term insurance financing note 1,074 — Accrued professional fees 511 345 Accrued compensation and benefits 2,103 — Accrued commercial expenses 502 — Accrued patent expenses 1,704 54 Other 553 264 Total accrued expenses & other current liabilities $ 20,189 $ 4,950

STOCK BASED COMPENSATION (Table

STOCK BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2020
Stock-based compensation
Schedule of stock-based compensation expenses	Total stock‑based compensation expense recorded for employees, directors and non‑employees (in thousands): Year Ended December 31, (in thousands) 2020 2019 Research and development $ $ 2,580 $ 2,762 General and administrative 5,446 3,409 Total stock-based compensation expense $ 8,026 $ 6,171 Stock Option Activity
Schedule of options outstanding	The following table summarizes the information about options outstanding at December 31, 2020 (in thousands, except share and per share data): Weighted-Average Weighted- Remaining Aggregate Options Average Contractual Intrinsic (in thousands, except for share data) Outstanding Exercise Price Term (in years) Value Outstanding at December 31, 2019 4,079,888 $ 5.11 8.26 $ 82,327 Options granted 1,105,604 30.73 Options exercised (522,160) 3.48 19,037 Forfeited (133,657) 12.45 Expired — Outstanding at December 31, 2020 4,529,675 $ 12.87 8.49 $ 51,103 Exercisable at December 31, 2020 2,226,178 $ 5.69 7.94 $ 36,903 Nonvested at December 31, 2020 2,303,497 $ 19.80 9.01 $ 14,200
Schedule of restricted stock units outstanding	Weighted-Average Aggregate Grant Date Intrinsic Value (in thousands, except for share data) Shares Fair Value As of December 31, 2020 Outstanding at December 31, 2019 — $ — Awarded 206,679 36.09 Released - — Forfeited (150) 44.02 Outstanding at December 31, 2020 206,529 $ 36.08 $ 4,546 Nonvested at December 31, 2020 206,529 $ 36.08 $ 4,546 Weighted Average Remaining Recognition Period (in years) 3.43
Stock options - Service conditions only
Stock-based compensation
Schedule of valuation assumptions	Year Ended December 31, 2020 2019 Expected term (in years) 6.1 5.7 Volatility 69.70 % 72.54 % Risk-free interest rate 0.51 % 2.17 % Dividend yield 0.00 % 0.00 %
Stock options - Service, performance and market conditions
Stock-based compensation
Schedule of valuation assumptions	Time to expiration (in years) 10.0 Volatility 68.54 % Risk-free interest rate 2.64 % Dividend yield 0.00 % Cost of equity 24.00 % Fair value of underlying common stock (as of valuation date) $ 5.85

WARRANTS (Tables)

WARRANTS (Tables)	12 Months Ended
	Dec. 31, 2020
Warrants
Schedule of warrants outstanding	Warrants Outstanding as of December 31, 2019 462,364 Warrants granted and issued — Warrants exercised (308,891) Warrants exchanged — Balance as of December 31, 2020 153,473
Warrants Issued with Series A Preferred Stock | 2017 Warrants
Warrants
Schedule of fair value of warrants using the Black Scholes option pricing model	Contractual term (in years) 10.0 Volatility 74.48 % Risk-free interest rate 3.20 % Dividend yield 0.00 %
Warrants Issued with Series B Preferred Stock | 2018 Warrants
Warrants
Schedule of fair value of warrants using the Black Scholes option pricing model	Contractual term (in years) 10.0 Volatility 73.22 % Risk-free interest rate 2.70 % Dividend yield 0.00 %
Warrants Issued with Series B Preferred Stock | 2019 Warrants
Warrants
Schedule of fair value of warrants using the Black Scholes option pricing model	Contractual term (in years) 10.0 Volatility 73.22 % Risk-free interest rate 2.70 % Dividend yield 0.00 %

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2020
LEASES
Summary of lease assets and liabilities	Operating December 31, December 31, ROU Assets and Liabilities Balance Sheet Location 2020 2019 ROU - Asset Right-of-use assets $ 1,712 $ 2,035 Lease liabilities (current) Operating lease liabilities, current 406 356 Lease liabilities (non-current) Operating lease liabilities, non-current 1,332 1,683
Summary of lease related costs	Operating (in thousands) Lease Cost Statement of Operations Location 2020 2019 Operating Lease Cost General and administrative $ 487 $ 81 Total Lease Cost $ 487 $ 81
Summary of lease terms and discount rates	Year Ended Year Ended December 31, December 31, Other Information 2020 2019 Weighted-average remaining lease term Operating leases 3.8 4.8 Weighted-average discount rate Operating leases
Summary of maturities of lease liabilities	Operating Year (in thousands) 2021 $ 494 2022 507 2023 515 2024 424 Thereafter — Total lease payments 1,940 Less: interest 202 Total lease liabilities $ 1,738

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
INCOME TAXES
Summary of deferred income tax assets and liabilities	Deferred income tax assets and liabilities consist of the following (in thousands): Year ended December 31, 2020 2019 Deferred Tax Assets Operating Lease Liability $ 541 $ 706 Stock-based compensation 3,788 1,582 License fee 630 22 Net operating loss carryforwards 49,094 19,937 Research and development tax credits 9,037 — Other 689 — Total Deferred Tax Assets $ 63,779 $ 22,247 Valuation Allowance $ (63,246) $ (21,542) Net Deferred Tax Assets $ 533 $ 705 Deferred Tax Liabilities Right of Use Asset (533) (705) Net Deferred Tax Liabilities $ (533) $ (705) Net deferred tax asset (liability) $ — $ —
Schedule of the U.S. federal statutory corporate tax rate reconciles to the Company’s effective tax rate	Year Ended December 31, 2020 2019 Federal statutory rate 21.0 % 21.0 % State and local taxes net of federal tax benefit 9.9 13.2 Credits 9.6 0.0 Permanent Differences 3.9 (33.4) Change in valuation allowance (44.3) (0.7) Other (0.1) (0.1) Total % %

NET LOSS PER COMMON SHARE (Tabl

NET LOSS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2020
NET LOSS PER COMMON SHARE
Schedule of computation of basic and diluted net loss per common share	The following table sets forth the computation of basic and diluted net loss per common share (in thousands, except share and per share data): Years Ended December 31, (in thousands, except for share data) 2020 2019 Numerator: Net loss $ (93,961) $ (45,513) Denominator: Weighted-average common stock outstanding 21,966,326 12,831,221 Net loss per share attributable to common stockholders - basic and diluted $ (4.28) $ (3.55)
Schedule of potential dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders	As of December 31, 2020 2019 Options to purchase common stock 4,529,675 4,079,888 Restricted stock units 206,529 — Warrants to purchase common stock 153,473 462,364

ORGANIZATION AND SUMMARY OF S_3

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock issued (Details) $ / shares in Units, $ in Millions	Feb. 19, 2021USD ($)$ / sharesshares	Jun. 20, 2020USD ($)	Jun. 04, 2020USD ($)	Jan. 28, 2020USD ($)$ / sharesshares	Nov. 12, 2019USD ($)$ / sharesshares	May 16, 2019USD ($)$ / sharesshares	Apr. 26, 2019	Jun. 30, 2020USD ($)	Dec. 31, 2020shares
IPO
Convertible preferred stock, outstanding (in shares)						0
IPO
IPO
Issuance of common stock (in shares)						4,000,000
Issue price (in dollars per share) | $ / shares						$ 10
Aggregate gross proceeds from issuance | $						$ 40
Net proceeds after deducting underwriting discounts and commissions and offering costs | $						$ 34.6
Stock split ratio							55.2486
Conversion of convertible preferred stock into common stock upon closing of the IPO (in shares)						7,538,671
Number of shares issued for each share of convertible preferred stock converted						1
Private placement
IPO
Issuance of common stock (in shares)					1,380,344
Issue price (in dollars per share) | $ / shares					$ 14.50
Net proceeds from issuance of common stock | $					$ 18.4
Secondary public offering
IPO
Issue price (in dollars per share) | $ / shares				$ 45.50
Net proceeds from issuance of common stock | $				$ 134.1
Secondary public offering, excluding underwriters' option
IPO
Issuance of common stock (in shares)				2,741,489
Underwriters' option
IPO
Issuance of common stock (in shares)				411,223
Underwriters' option | Subsequent Event.
IPO
Issuance of common stock (in shares)	450,000
Registration of Form S-3 offering/Shelf Registration Statement
IPO
Issuance of common stock (in shares)									3,450,000
Maximum value of shares authorized to be sold in stock offering. | $			$ 300
Equity Distribution Agreement
IPO
Issuance of common stock (in shares)									0
Maximum value of shares authorized to be sold in stock offering. | $		$ 100						$ 100
Net proceeds from issuance of common stock | $								$ 0
February offering | Subsequent Event.
IPO
Issuance of common stock (in shares)	3,450,000
Issue price (in dollars per share) | $ / shares	$ 23
Net proceeds from issuance of common stock | $	$ 74.3

ORGANIZATION AND SUMMARY OF S_4

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Offering Costs (Details) - USD ($) $ in Millions	1 Months Ended
	May 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Deferred offering cost
Reclassification of deferred offering costs	$ 2.6
Deferred offering costs		$ 0	$ 0

ORGANIZATION AND SUMMARY OF S_5

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-based compensation (Details)	12 Months Ended
	Dec. 31, 2020
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Dividend yield (as a percent)	0.00%

ORGANIZATION AND SUMMARY OF S_6

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Uncertain tax positions	$ 0	$ 0
Accrued interest and penalties	$ 0	$ 0

ORGANIZATION AND SUMMARY OF S_7

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted Accounting Pronouncements (Details)	Jan. 01, 2020
ASU 2016-13, Financial Instruments
Recently Adopted Accounting Pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true

LICENSE AGREEMENT - Columbia (D

LICENSE AGREEMENT - Columbia (Details) $ in Thousands	Oct. 03, 2019USD ($)	Mar. 31, 2019USD ($)item	Jan. 31, 2019USD ($)	Oct. 31, 2016USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)
Agreements
Research and development					$ 61,788	$ 32,350
General and administrative					32,678	13,232
Operating expenses					94,466	45,582
Accrued expenses and other current liabilities					20,189	4,950	$ 20,189
Accounts payable					640	8,793	640
Columbia University
Agreements
Research and development					300	100
General and administrative					100	500
Operating expenses							2,300
Accrued expenses and other current liabilities					100	100	100
Accounts payable					$ 0	$ 100	$ 0
2016 license agreement | Columbia University
Agreements
Percentage of outstanding common stock issued				5.00%
Fair value of stock issued				$ 500
Written notice period for termination of agreement				90 days
Written notice period for termination of agreement, uncured material breach				30 days
Extended written notice period for termination of agreement, attempt to cure material breach				90 days
2016 license agreement | Columbia University | Minimum
Agreements
Percentage of sublicensing revenue, if sublicenses rights granted				10.00%
2016 license agreement | Columbia University | Maximum
Agreements
Payment on achievement of specified development and regulatory milestones				$ 1,300
Payment on achievement of specified level of aggregate annual net sales				$ 1,000
Percentage of sublicensing revenue, if sublicenses rights granted				20.00%
2019 license agreement | Columbia University
Agreements
Written notice period for termination of agreement			90 days
Written notice period for termination of agreement, uncured material breach			30 days
Extended written notice period for termination of agreement, attempt to cure material breach			90 days
2019 license agreement | Columbia University | Minimum
Agreements
Percentage of sublicensing revenue, if sublicenses rights granted			10.00%
2019 license agreement | Columbia University | Maximum
Agreements
Payment on achievement of specified development and regulatory milestones			$ 1,300
Payment on achievement of specified level of aggregate annual net sales			$ 1,000
Percentage of sublicensing revenue, if sublicenses rights granted			50.00%
2019 research agreement | Columbia University
Agreements
Agreement term		12 months
Written notice period for termination of agreement		30 days
Number of parts | item		2
2019 research agreement - Part I | Columbia University
Agreements
Agreement term		6 months
Payment to be made		$ 100
2019 research agreement - Part II | Columbia University
Agreements
Agreement term		6 months
Payment to be made		$ 200
P13k Research agreement | Columbia University
Agreements
Agreement term	18 months
Written notice period for termination of agreement	30 days
Payment to be made	$ 400

LICENSE AGREEMENT - Miami Unive

LICENSE AGREEMENT - Miami University (Details) - USD ($)	Oct. 28, 2020	Dec. 31, 2020	Dec. 31, 2019
Agreements
Research and development		$ 61,788,000	$ 32,350,000
General and administrative		32,678,000	13,232,000
Accrued expenses and other current liabilities		20,189,000	$ 4,950,000
2020 license agreement | University of Miami
Agreements
Amount of first payment to be made for license issue fee	$ 1,100,000
Amount of second payment to be made for license issue fee, due on first anniversary of the date of license	500,000
Payment to be made on achievement of specified patenting and development milestones	2,200,000
Payment to be made on achievement of late stage regulatory milestones	$ 4,100,000
Agreement term	10 years
Written notice period for termination of agreement	60 days
Written notice period of material breach leading to termination	60 days
Research and development		2,000,000
General and administrative		36,000
Accrued expenses and other current liabilities		1,600,000
2020 license agreement | University of Miami | Minimum
Agreements
Royalties payment (as a percent)	0.88%
Non-royalty sublicensing revenue payment (as a percent)	$ 15
2020 license agreement | University of Miami | Maximum
Agreements
Royalties payment (as a percent)	5.00%
Non-royalty sublicensing revenue payment (as a percent)	$ 25
2020 Research Agreement | University of Miami
Agreements
Accrued expenses and other current liabilities		3,740
Consideration		$ 300,000

FAIR VALUE MEASUREMENTS - FV hi

FAIR VALUE MEASUREMENTS - FV hierarchy (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	$ 57,466	$ 18,850
Marketable securities	39,363	20,004
Total financial assets measured at fair value on a recurring basis	96,829	38,854
Level 1
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	57,466	18,850
Total financial assets measured at fair value on a recurring basis	57,466	18,850
Level 2
Financial assets or liabilities measured at fair value on a recurring basis
Marketable securities	39,363	20,004
Total financial assets measured at fair value on a recurring basis	39,363	20,004
Cash
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	6,691	18,783
Cash | Level 1
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	6,691	18,783
Money market funds
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	50,775	67
Money market funds | Level 1
Financial assets or liabilities measured at fair value on a recurring basis
Cash and cash equivalents	50,775	67
Commercial paper and corporate bonds
Financial assets or liabilities measured at fair value on a recurring basis
Marketable securities		7,520
Commercial paper and corporate bonds | Level 2
Financial assets or liabilities measured at fair value on a recurring basis
Marketable securities		7,520
U.S. government agency debt securities
Financial assets or liabilities measured at fair value on a recurring basis
Marketable securities	39,363	12,484
U.S. government agency debt securities | Level 2
Financial assets or liabilities measured at fair value on a recurring basis
Marketable securities	$ 39,363	$ 12,484

FAIR VALUE MEASUREMENTS - Trans

FAIR VALUE MEASUREMENTS - Transfers (Details) $ in Thousands	Dec. 31, 2020USD ($)
FAIR VALUE MEASUREMENTS
Assets, transfer from level 1 to level 2	$ 0
Assets, transfer from level 2 to level 1	$ 0

INVESTMENTS - By type (Details)

INVESTMENTS - By type (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Marketable securities by type
Cost	$ 39,475	$ 20,006
Gross Unrealized Gains	11	19
Gross Unrealized Losses	(123)	(21)
Estimated Fair Value	39,363	20,004
Commercial paper, corporate bonds, and CDs with original maturity less than 1 year
Marketable securities by type
Cost		7,540
Gross Unrealized Gains	0
Gross Unrealized Losses		(20)
Estimated Fair Value	0	7,520
U.S. government agency debt securities
Marketable securities by type
Cost	39,475	12,466
Gross Unrealized Gains	11	19
Gross Unrealized Losses	(123)	(1)
Estimated Fair Value	$ 39,363	$ 12,484

INVESTMENTS - Additional Inform

INVESTMENTS - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
INVESTMENTS
Gross unrealized loss	$ 123	$ 21
Unrealized loss as a percentage of total amortized costs basis of corporate bond portfolio	0.25%

INVESTMENTS - By contractual ma

INVESTMENTS - By contractual maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Marketable securities by maturity
Cost	$ 39,475	$ 20,006
Gross Unrealized Gains	11	19
Gross Unrealized Losses	(123)	(21)
Estimated Fair Value	39,363	20,004
Securities, Due In One Year Or Less
Marketable securities by maturity
Cost	39,475	20,006
Gross Unrealized Gains	11	19
Gross Unrealized Losses	(123)	(21)
Estimated Fair Value	$ 39,363	$ 20,004

INVESTMENTS - Other than tempor

INVESTMENTS - Other than temporary impairment loss (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Marketable securities realized gain (loss) recorded
Gross realized loss from sale of marketable securities	$ 100
Gross realized gain from sale of marketable securities	$ 50

INVESTMENTS - Unrealized losses

INVESTMENTS - Unrealized losses and fair values of available-for-sale securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Securities in an unrealized loss position less than 12 months
Unrealized Losses Less Than 12 months	$ (123)	$ (21)
Estimated Fair Value Less Than 12 Months	14,073	11,017
Total Unrealized Losses	(123)	(21)
Total Estimated Fair Value	14,073	11,017
Commercial paper and corporate bonds
Securities in an unrealized loss position less than 12 months
Unrealized Losses Less Than 12 months		(20)
Estimated Fair Value Less Than 12 Months		7,520
Total Unrealized Losses		(20)
Total Estimated Fair Value		7,520
U.S. government agency debt securities
Securities in an unrealized loss position less than 12 months
Unrealized Losses Less Than 12 months	(123)	(1)
Estimated Fair Value Less Than 12 Months	14,073	3,497
Total Unrealized Losses	(123)	(1)
Total Estimated Fair Value	$ 14,073	$ 3,497

PREPAID EXPENSES AND OTHER CU_3

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
PREPAID EXPENSES AND OTHER CURRENT ASSETS
Prepaid research and development expenses	$ 2,349	$ 5,872
Insurance Premium Asset	1,463
Prepaid rent expenses	108	142
Prepaid insurance expenses	91	1,196
Prepaid Commercial and Patient Advocacy	968
Research and Development Tax Credit Receivable	500
Interest Receivable	5
Other prepaid expenses and current assets	280	91
Total prepaid expenses & other current assets	$ 5,764	$ 7,301

ACCRUED EXPENSES AND OTHER CU_3

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES
Accrued pre-clinical and clinical expenses	$ 13,742	$ 4,287
Short-term insurance financing note	1,074
Accrued professional fees	511	345
Accrued compensation and benefits	2,103
Accrued commercial expenses	502
Accrued patent expenses	1,704	54
Other	553	264
Total accrued expenses & other current liabilities	$ 20,189	$ 4,950

STOCK BASED COMPENSATION - Plan

STOCK BASED COMPENSATION - Plans (Details) - shares	1 Months Ended
	May 31, 2019	Jan. 01, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Options outstanding (in shares)			4,529,675	4,079,888
2019 Plan
Stock-based compensation
New shares reserved (in shares)	1,618,841
Reserved shares available from 2016 Plan (in shares)	2,911,159
Increase in number of shares reserved and available for issuance (as a percent)	5.00%
Number of shares available for future issuance			0
2019 Plan | Subsequent Event.
Stock-based compensation
Number of shares available for future issuance		1,124,683
2019 Plan | Maximum
Stock-based compensation
Shares reserved (in shares)	4,530,000
2019 Plan | Options
Stock-based compensation
Maximum number of shares authorized for issuance	13,000,000
Expiration period	10 years
Vesting period	4 years

STOCK BASED COMPENSATION - Stoc

STOCK BASED COMPENSATION - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Total stock-based compensation expense	$ 8,026	$ 6,171
Research and development
Stock-based compensation
Total stock-based compensation expense	2,580	2,762
General and administrative
Stock-based compensation
Total stock-based compensation expense	$ 5,446	$ 3,409

STOCK BASED COMPENSATION - Opti

STOCK BASED COMPENSATION - Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Options granted (in shares)	1,105,604	2,969,945
Weighted-average fair value of options granted (in dollars per share)	$ 18.84	$ 5.68
Unrecognized stock-based compensation balance for unvested options	$ 25.2	$ 12.5
Total fair value of options vested	$ 0.5	$ 3.5
Options
Stock-based compensation
Unrecognized stock-based compensation balance for unvested options expected to be recognized (in years)	2 years 7 months 6 days	1 year 8 months 12 days

STOCK BASED COMPENSATION - Op_2

STOCK BASED COMPENSATION - Options activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Options Outstanding
Outstanding at beginning of period (in shares)		4,079,888
Options granted (in shares)		1,105,604	2,969,945
Options exercised (in shares)		(522,160)
Forfeited (in shares)		(133,657)
Outstanding at end of period (in shares)		4,529,675	4,079,888
Exercisable at end of period (in shares)		2,226,178
Nonvested at end of period (in shares)		2,303,497
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)		$ 5.11
Options granted (in dollars per share)		30.73
Options exercised (in dollars per share)		3.48
Options forfeited (in dollars per share)		12.45
Outstanding at end of period (in dollars per share)		12.87	$ 5.11
Exercisable at end of period (in dollars per share)		5.69
Nonvested at end of period (in dollars per share)		$ 19.80
Weighted-Average Remaining Contractual Term-in years
Outstanding		8 years 5 months 27 days	8 years 3 months 4 days
Exercisable		7 years 11 months 9 days
Nonvested		9 years 4 days
Aggregate Intrinsic Value
Options exercised (in dollars)		$ 19,037
Outstanding (in dollars)		51,103	$ 82,327
Exercisable (in dollars)		36,903
Nonvested (in dollars)		$ 14,200
Incremental stock-based compensation expense	$ 0

STOCK BASED COMPENSATION - Valu

STOCK BASED COMPENSATION - Valuation assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Valuation Assumptions
Dividend yield (as a percent)	0.00%
Stock options - Service conditions only
Valuation Assumptions
Expected term/Time to expiration (in years)	6 years 1 month 6 days	5 years 8 months 12 days
Volatility	69.70%	72.54%
Risk-free interest rate	0.51%	2.17%
Dividend yield (as a percent)	0.00%	0.00%
Stock options - Service, performance and market conditions
Valuation Assumptions
Expected term/Time to expiration (in years)	10 years
Volatility	68.54%
Risk-free interest rate	2.64%
Dividend yield (as a percent)	0.00%
Cost of equity	24.00%
Fair value of underlying common stock (as of valuation date)	$ 5.85

STOCK BASED COMPENSATION - Op_3

STOCK BASED COMPENSATION - Options that Contain Service, Performance and Market Conditions - Grants (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Options granted (in shares)	1,105,604	2,969,945
Fair value at grant date	$ 0.5	$ 3.5
Options outstanding (in shares)	4,529,675	4,079,888
Stock options - Service, performance and market conditions
Stock-based compensation
Options granted (in shares)	159,501
Fair value at grant date	$ 0.5
Options outstanding (in shares)	0
Stock options - Service, performance and market conditions | Minimum
Stock-based compensation
Derived service period	P1D
Stock options - Service, performance and market conditions | Maximum
Stock-based compensation
Derived service period	P3Y

STOCK BASED COMPENSATION - Op_4

STOCK BASED COMPENSATION - Options that Contain, Service, Performance and Market Conditions - Expense (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Stock-based compensation expense		$ 8,026	$ 6,171
Options outstanding (in shares)		4,529,675	4,079,888
Stock options - Service, performance and market conditions
Stock-based compensation
Options vested (in shares)		79,778
Stock-based compensation expense		$ 700
Options outstanding (in shares)		0
Former Interim Chief Financial Officer | Stock options - Service, performance and market conditions
Stock-based compensation
Options vested (in shares)	79,723
General and administrative
Stock-based compensation
Stock-based compensation expense		$ 5,446	$ 3,409
General and administrative | Former Interim Chief Financial Officer | Stock options - Service, performance and market conditions
Stock-based compensation
Stock-based compensation expense			$ 600

STOCK BASED COMPENSATION - RSUs

STOCK BASED COMPENSATION - RSUs (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 10, 2020	Jun. 04, 2020	Mar. 09, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020
Stock-based compensation
Stock-based compensation expense				$ 8,026	$ 6,171
Restricted Stock Units (RSUs)
Stock-based compensation
Vesting period	4 years	4 years	4 years
Fair value of awards (in dollars)	$ 1,400	$ 4,800	$ 1,300
Fair value of awards (in dollars per share)	$ 23.15	$ 44.02	$ 34.28	$ 36.09
Stock-based compensation expense				$ 1,000
Unrecognized stock-based compensation balance for unvested awards						$ 6,600
Summary of restricted stock units outstanding
Awarded (in shares)	61,553	108,662	36,464	206,679
Forfeited (in shares)				(150)
Outstanding at end of period ( in shares)				206,529
Nonvested at end of period (in shares)						206,529
Weighted-Average Grant Date Fair Value
Awarded (in dollars per share)	$ 23.15	$ 44.02	$ 34.28	$ 36.09
Forfeited (in dollars per share)				44.02
Outstanding at end of period (in dollars per share)				36.08
Nonvested at end of period (in dollars per share)				$ 36.08		$ 36.08
Aggregate Intrinsic Value
Outstanding at end of period (in dollars)						$ 4,546
Nonvested at end of period (in dollars)						$ 4,546
Weighted Average Remaining Recognition Period				3 years 5 months 5 days
Restricted Stock Units (RSUs) | Tranche one
Stock-based compensation
Vesting percentage	25.00%	25.00%	25.00%
Vesting period	1 year	1 year	1 year
Restricted Stock Units (RSUs) | Tranche two
Stock-based compensation
Vesting percentage	25.00%	25.00%	25.00%
Vesting period	1 year	1 year	1 year
Restricted Stock Units (RSUs) | Tranche three
Stock-based compensation
Vesting percentage	25.00%	25.00%	25.00%
Vesting period	1 year	1 year	1 year
Restricted Stock Units (RSUs) | Tranche four
Stock-based compensation
Vesting percentage	25.00%	25.00%	25.00%
Vesting period	1 year	1 year	1 year

STOCK BASED COMPENSATION - 2019

STOCK BASED COMPENSATION - 2019 Employee Stock Purchase Plan (Details) - 2019 ESPP - shares	1 Months Ended	12 Months Ended
	May 31, 2019	Dec. 31, 2020
Stock-based compensation
Shares authorized (in shares)	180,000
Shares issued under ESPP		0
Maximum
Stock-based compensation
Increase in number of shares reserved and available for issuance (as a percent)	1.00%
Increase in number of shares reserved and available for issuance (in shares)	360,000

STOCKHOLDERS' EQUITY - Authoriz

STOCKHOLDERS' EQUITY - Authorized, issued and outstanding and Common Stock (Details)	12 Months Ended
	Dec. 31, 2020Vote$ / sharesshares	Dec. 31, 2019$ / sharesshares
STOCKHOLDERS’ EQUITY
Common Stock, authorized (in shares) | shares	100,000,000	100,000,000
Common Stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized (in shares) | shares	10,000,000	10,000,000
Convertible preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Number of votes per common stock | Vote	1

STOCKHOLDERS' EQUITY - Equity D

STOCKHOLDERS' EQUITY - Equity Distribution Agreement (Details) - Equity Distribution Agreement - USD ($) $ in Millions	Jun. 20, 2020	Jun. 30, 2020
STOCKHOLDERS' EQUITY
Maximum value of shares authorized to be sold in stock offering.	$ 100	$ 100
Maximum amount paid to Goldman (as a percent)		3.00%
Net proceeds from issuance of common stock		$ 0

WARRANTS - Issued with Series A

WARRANTS - Issued with Series A Preferred Stock (Details) $ / shares in Units, $ in Thousands	Feb. 24, 2020shares	Feb. 21, 2020itemshares	Dec. 05, 2019shares	Jan. 26, 2017USD ($)$ / sharesshares	Dec. 31, 2020YRateshares	Dec. 31, 2019USD ($)
Warrants
Warrants to purchase common stock (in dollars) | $						$ 80
Warrants exercised (in shares)					308,891
2017 Warrants | Warrants Issued with Series A Preferred Stock
Warrants
Warrants to purchase common stock (in shares)				309,389
Warrants to purchase common stock (in dollars) | $				$ 200
Exercise price (in dollars per share) | $ / shares				$ 2.49
Number of warrant holders that exercised options | item		2
Warrants exercised (in shares)	72,818	185,634	20,000
Exercise of warrants of common stock (in shares)	69,094	176,092	17,026
2017 Warrants | Warrants Issued with Series A Preferred Stock | Contractual term (in years)
Warrants
Measurement input | Y					10
2017 Warrants | Warrants Issued with Series A Preferred Stock | Volatility
Warrants
Measurement input | Rate					0.7448
2017 Warrants | Warrants Issued with Series A Preferred Stock | Risk-free interest rate
Warrants
Measurement input | Rate					0.0320
2017 Warrants | Warrants Issued with Series A Preferred Stock | Dividend yield
Warrants
Measurement input | Rate					0

WARRANTS - Issued with the 2018

WARRANTS - Issued with the 2018 Notes (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 24, 2020	Feb. 24, 2020	Nov. 05, 2018	Dec. 31, 2020	Dec. 31, 2019	Jan. 18, 2018
Warrants
Warrants to purchase common stock (in dollars)					$ 80
Warrants exercised (in shares)				308,891
Warrants Issued with the 2018 Notes
Warrants
Initial fair value recorded as debt discount (in dollars)						$ 100
Warrants to purchase common stock (in shares)			76,847
Warrants to purchase common stock (in dollars)			$ 300
Exercise price (in dollars per share)			$ 6.59
Warrants exercised (in shares)	20,331	386
Stock issued in exercise of warrants (in shares)	17,369	333

WARRANTS - Issued with Series B

WARRANTS - Issued with Series B Preferred Stock (Details) $ / shares in Units, $ in Thousands	Jun. 24, 2020shares	Feb. 24, 2020shares	Jan. 14, 2020shares	Feb. 28, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2020YRateshares	Dec. 31, 2019USD ($)
Warrants
Warrants to purchase common stock (in dollars) | $							$ 80
Warrants exercised (in shares)						308,891
Warrants Issued with Series B Preferred Stock
Warrants
Warrants exercised (in shares)	24,309	5,193	220
Stock issued in exercise of warrants (in shares)	19,882	4,313	146
2018 Warrants | Warrants Issued with Series B Preferred Stock
Warrants
Warrants to purchase common stock (in shares)					72,261
Warrants to purchase common stock (in dollars) | $					$ 200
Exercise price (in dollars per share) | $ / shares					$ 8.24
Expiration term					10 years
2018 Warrants | Warrants Issued with Series B Preferred Stock | Contractual term (in years)
Warrants
Measurement input | Y						10
2018 Warrants | Warrants Issued with Series B Preferred Stock | Volatility
Warrants
Measurement input | Rate						0.7322
2018 Warrants | Warrants Issued with Series B Preferred Stock | Risk-free interest rate
Warrants
Measurement input | Rate						0.0270
2018 Warrants | Warrants Issued with Series B Preferred Stock | Dividend yield
Warrants
Measurement input | Rate						0
2019 Warrants | Warrants Issued with Series B Preferred Stock
Warrants
Warrants to purchase common stock (in shares)				23,867
Warrants to purchase common stock (in dollars) | $				$ 100
Exercise price (in dollars per share) | $ / shares				$ 8.24
Expiration term				10 years
2019 Warrants | Warrants Issued with Series B Preferred Stock | Contractual term (in years)
Warrants
Measurement input | Y						10
2019 Warrants | Warrants Issued with Series B Preferred Stock | Volatility
Warrants
Measurement input						0.7322
2019 Warrants | Warrants Issued with Series B Preferred Stock | Risk-free interest rate
Warrants
Measurement input						0.0270
2019 Warrants | Warrants Issued with Series B Preferred Stock | Dividend yield
Warrants
Measurement input						0

WARRANTS - Warrant Activity (De

WARRANTS - Warrant Activity (Details)	12 Months Ended
	Dec. 31, 2020shares
WARRANTS
Outstanding as of beginning of period	462,364
Warrants exercised	(308,891)
Outstanding as of end of period	153,473

LEASES - ROU Assets and Liabili

LEASES - ROU Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ROU Assets and Liabilities
ROU - Asset	$ 1,712	$ 2,035
Lease liabilities (current)	406	356
Lease liabilities (non-current)	$ 1,332	$ 1,683

LEASES - Lease Cost (Details)

LEASES - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases
Operating Lease Cost	$ 487	$ 81
General and administrative
Leases
Operating Lease Cost	$ 487	$ 81

LEASES - Lease terms and discou

LEASES - Lease terms and discount rates (Details)	Dec. 31, 2020	Dec. 31, 2019
LEASES
Weighted-average remaining lease term - operating leases	3 years 9 months 18 days	4 years 9 months 18 days
Weighted-average discount rate — operating leases	5.69%	5.69%

LEASES - Maturities of Lease Li

LEASES - Maturities of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
LEASES
2021	$ 494
2022	507
2023	515
2024	424
Total lease payments	1,940
Less: interest	202
Total lease liabilities	$ 1,738

INCOME TAXES - Provision (Detai

INCOME TAXES - Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
INCOME TAXES
Current tax provision	$ 0	$ 0
Deferred tax provision	$ 0	$ 0

INCOME TAXES - Deferred taxes (

INCOME TAXES - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets
Operating lease liability	$ 541	$ 706
Stock-based compensation	3,788	1,582
License fee	630	22
Net operating loss carryforwards	49,094	19,937
Research and development tax credits	9,037
Other	689
Total Deferred Tax Assets	63,779	22,247
Valuation Allowance	(63,246)	(21,542)
Net Deferred Tax Assets	533	705
Deferred Tax Liabilities
Right of Use Asset	(533)	(705)
Net Deferred Tax Liabilities	(533)	(705)
Net deferred tax asset (liability)	$ 0	$ 0

INCOME TAXES - NOLs (Details)

INCOME TAXES - NOLs (Details) $ in Millions	Dec. 31, 2020USD ($)
Federal
Income taxes
NOLs	$ 157.1
NOLs expiring through 2037	3.3
NOLs not subject expiration	153.8
State
Income taxes
NOLs	$ 158

INCOME TAXES - Tax credit carry

INCOME TAXES - Tax credit carryforward (Details) $ in Millions	Dec. 31, 2020USD ($)
Research tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 3.7
Orphan drug credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 5.3

INCOME TAXES - Valuation allowa

INCOME TAXES - Valuation allowance (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
INCOME TAXES
Net deferred tax asset (liability)	$ 0	$ 0
Valuation Allowance	$ (63,246)	$ (21,542)

INCOME TAXES - Income tax rate

INCOME TAXES - Income tax rate reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Tax rate reconciliation
Federal statutory rate (as a percent)	21.00%	21.00%
State and local taxes net of federal tax benefit (as a percent)	9.90%	13.20%
Credits (as a percent)	9.60%	0.00%
Permanent Differences (as a percent)	3.90%	(33.40%)
Change in valuation allowance (as a percent)	(44.30%)	(0.70%)
Other (as a percent)	(0.10%)	(0.10%)
Total (as a percent)	0.00%	0.00%

BENEFIT PLANS (Details)

BENEFIT PLANS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
BENEFIT PLANS
Employer matching contributions to the plan	$ 100,000	$ 69,000

NET LOSS PER COMMON SHARE - EPS

NET LOSS PER COMMON SHARE - EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to common stockholders—basic	$ (93,961)	$ (45,513)
Net loss attributable to common stockholders— diluted	$ (93,961)	$ (45,513)
Denominator:
Weighted-average common stock outstanding	21,966,326	12,831,221
Net loss per share attributable to common stockholders—basic and diluted	$ (4.28)	$ (3.55)

NET LOSS PER COMMON SHARE - Ant

NET LOSS PER COMMON SHARE - Anti-dilutive securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Options
Antidilutive securities excluded from computation of loss per share
Potential dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders	4,529,675	4,079,888
Restricted Stock Units (RSUs)
Antidilutive securities excluded from computation of loss per share
Potential dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders	206,529
Warrants Liability
Antidilutive securities excluded from computation of loss per share
Potential dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders	153,473	462,364

RELATED PARTIES (Details)

RELATED PARTIES (Details) - LaunchLabs Agreement - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Payments to related party	$ 89,000	$ 85,000
Due to related parties	$ 0

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 19, 2021	Jan. 28, 2020
Underwriters' option
Subsequent event
Issuance of common stock (in shares)		411,223
Subsequent Event. | February offering
Subsequent event
Issuance of common stock (in shares)	3,450,000
Issue price (in dollars per share)	$ 23
Net proceeds from issuance of common stock	$ 74.3
Subsequent Event. | Underwriters' option
Subsequent event
Issuance of common stock (in shares)	450,000