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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Jun. 14, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Entity Registrant Name	Applied Therapeutics Inc.
Entity Central Index Key	0001697532
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
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
Entity Common Stock, Shares Outstanding		17,052,202

Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 14,686	$ 18,748
Prepaid expenses and other current assets	2,186	1,498
Total current assets	16,872	20,246
TOTAL ASSETS	16,872	20,246
CURRENT LIABILITIES:
Accounts payable	2,649	3,015
Accrued expenses and other current liabilities	3,679	1,413
Total current liabilities	6,328	4,428
Total liabilities	6,328	4,428
Convertible preferred stock	38,461	35,410
STOCKHOLDERS’ DEFICIT:
Common stock, $0.0001 par value; 20,441,982 shares authorized as of March 31, 2019 and December 31, 2018; 5,513,531 shares issued and outstanding as of March 31, 2019 and December 31, 2018
Additional paid-in capital	2,070	1,665
Accumulated deficit	(29,987)	(21,257)
Total stockholders’ deficit	(27,917)	(19,592)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT	16,872	20,246
Series A Convertible Preferred Stock
CURRENT LIABILITIES:
Convertible preferred stock	6,254	6,254
Series B Convertible Preferred Stock
CURRENT LIABILITIES:
Convertible preferred stock	$ 32,207	$ 29,156

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Convertible preferred stock, authorized (in shares)	10,883,950	10,883,950
Convertible preferred stock, outstanding (in shares)	7,538,671	7,095,746
Convertible preferred stock, liquidation preference (in dollars)	$ 40,281	$ 36,964
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, authorized (in shares)	20,441,982	20,441,982
Common Stock, issued (in shares)	5,513,531	5,513,531
Common stock, outstanding (in shares)	5,513,531	5,513,531
Series A Convertible Preferred Stock
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized (in shares)	3,093,898	3,093,898
Convertible preferred stock, issued (in shares)	3,093,898	3,093,898
Convertible preferred stock, outstanding (in shares)	3,093,898	3,093,898
Convertible preferred stock, liquidation preference (in dollars)	$ 7,000	$ 7,000
Series B Convertible Preferred Stock
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized (in shares)	7,790,052	7,790,052
Convertible preferred stock, issued (in shares)	4,444,773	4,001,848
Convertible preferred stock, outstanding (in shares)	4,444,773	4,001,848
Convertible preferred stock, liquidation preference (in dollars)	$ 33,281	$ 29,964

Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended
Condensed Statements of Operations - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
OPERATING EXPENSES:
Research and development	$ 6,874	$ 1,448
General and administrative	1,855	420
Total operating expenses	8,729	1,868
LOSS FROM OPERATIONS	(8,729)	(1,868)
OTHER INCOME (EXPENSE), NET:
Interest income (expense), net	(1)	(281)
Other expense		(186)
Total other income (expense), net	(1)	(467)
Net loss	(8,730)	(2,335)
Net loss attributable to common stockholders—basic	(8,730)	(2,335)
Net loss attributable to common stockholders— diluted	$ (8,730)	$ (2,335)
Net loss per share attributable to common stockholders—basic and diluted	$ (1.58)	$ (0.43)
Weighted-average common stock outstanding—basic and diluted	5,513,531	5,458,450

Condensed Statement of Convertible Preferred Stock $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) shares
Increase (Decrease) in Temporary Equity
Balance at beginning of period \| $	$ 35,410
Balance at beginning of period (in shares) \| shares	7,095,746
Balance at end of period \| $	$ 38,461
Balance at end of period (in shares) \| shares	7,538,671
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
Balance at end of period \| $	$ 6,254
Balance at end of period (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 (in shares) \| shares	442,925
Issuance of convertible preferred stock for cash, net of issuance costs \| $	$ 3,051
Balance at end of period \| $	$ 32,207
Balance at end of period (in shares) \| shares	4,444,773

Condensed Statement of Stockholders’ (Deficit) Equity - USD ($) $ in Thousands	Common Stock Par value $0.0001	Additional Paid-in Capital	Accumulated Deficit	Total
Balance at Dec. 31, 2017		$ 775	$ (4,736)	$ (3,961)
Balance (in shares) at Dec. 31, 2017	5,458,450
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		26		26
Net loss			(2,335)	(2,335)
Balance at Mar. 31, 2018		801	(7,071)	(6,270)
Balance (in shares) at Mar. 31, 2018	5,458,450
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 of convertible promissory notes		80		80
Stock-based compensation expense		325		325
Net loss			(8,730)	(8,730)
Balance at Mar. 31, 2019		$ 2,070	$ (29,987)	$ (27,917)
Balance (in shares) at Mar. 31, 2019	5,513,531

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
Condensed Statements of Cash Flows - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (8,730)	$ (2,335)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	325	26
Non-cash interest expense		282
Change in fair value of derivative liability		180
Change in fair value of warrant liability		6
Changes in operating assets and liabilities:
Prepaid expenses	(497)	(506)
Accounts payable	(366)	10
Accrued expenses and other current liabilities	2,266	1,206
Net cash used in operating activities	(7,002)	(1,131)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of Series B convertible preferred stock, net of cash issuance costs of $186	3,131
Proceeds from issuance of convertible promissory notes, net of cash issuance costs of $440		5,560
Payment of deferred offering costs	(191)
Net cash provided by financing activities	2,940	5,560
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(4,062)	4,429
Cash and cash equivalents at beginning of period	18,748	3,277
Cash and cash equivalents at end of period	14,686	7,706
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Derivative liability in connection with issuance of convertible promissory notes		1,896
Deferred offering costs in accrued expenses	872
Deferred offering costs still in accounts payable	79
Series B Convertible Preferred Stock
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Issuance of warrants	$ 80
2018 Notes
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Issuance of warrants		$ 74

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2019
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Applied Therapeutics, Inc. Notes to Condensed Financial Statements (Unaudited) 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. Through March 31, 2019, the Company has primarily funded its operations with proceeds from the sale of convertible preferred stock (see Note 8). On May 16, 2019, the Company completed an initial public offering (“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 approximately $34.0 million in net proceeds after deducting underwriting discounts and commissions and estimated offering costs. 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 will receive cash payment in lieu of receiving fractional shares. All share and per share amounts for all periods presented in the accompanying condensed 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. The condensed financial statements as of March 31, 2019, including share and per share amounts, do not give effect to the IPO. The accompanying unaudited condensed financial statements as of March 31, 2019 and for the three months ended March 31, 2019 and 2018 have been prepared by the Company in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2018 included in the Company’s final prospectus that forms a part of the Company’s Registration Statement on Form S-1 (Reg. No. 333-230838), filed with the SEC pursuant to Rule 424(b)(4) on May 14, 2019 (the “Prospectus”). The unaudited condensed financial statements have been prepared on the same basis as the audited financial statements. In the opinion of management, the accompanying unaudited condensed financial statements contain all adjustments which are necessary for a fair presentation of the Company’s financial position as of March 31, 2019, results of operations for the three months ended March 31, 2019 and 2018 and cash flows for the three months ended March 31, 2019 and 2018. Such adjustments are of a normal and recurring nature. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2019. 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 IPO, will allow the Company to continue its operations for at least 12 months. 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 The significant accounting policies and estimates used in preparation of the condensed financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2018, and the notes thereto, which are included in the Company’s Prospectus. Except as detailed below, there have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2019. Stock‑Based Compensation The Company accounts for its stock-based compensation as expense in the condensed 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 with the exception of stock options that also include service, performance and market conditions, which are valued using the Monte-Carlo simulation 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. A Monte-Carlo simulation is an analytical method used to estimate fair value by performing a large number of simulations or trial runs and thereby determining a value based on the possible outcomes from these trial runs based on the specific vesting conditions. The fair value of stock-based payments is recognized as expense over the requisite service period which is generally the vesting period, with the exception of the fair value of stock-based payments for awards that also include service, performance and market conditions, which is recognized as expense over the derived service period determined using the Monte-Carlo simulation. 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 convertible preferred stock and 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. The Company recorded deferred offering costs related to the IPO of $1.5 million as of March 31, 2019 in prepaid expenses and other current assets. Upon closing the IPO in May 2019, deferred offering costs were reclassified from prepaid and other current assets and recorded against the IPO proceeds reducing additional paid-in capital. Recently Adopted Accounting Pronouncements The new accounting pronouncements recently adopted by the Company are described in the Company’s audited financial statements as of and for the year ended December 31, 2018, and the notes thereto, which are included in the Company’s Prospectus as filed with the SEC on May 14, 2019. Except as described below, there have been no new accounting pronouncements adopted by the Company during the three months ended March 31, 2019. In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases on their balance sheet date (“ASU No. 2016-02”). ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018. In July 2018, an amendment was made that allows companies the option of using the effective date of the new standard as the initial application date (at the beginning of the period in which the new standard is adopted, rather than at the beginning of the earliest comparative period). This update includes a short-term lease exception for leases with a term of 12 months or less, in which a lessee can make an accounting policy election not to recognize the associated lease assets and lease liabilities on its balance sheet. Additionally, in March 2019, the FASB issued ASU 2019-01, Leases (Topic 842): Codification Improvements (“ASU No. 2019-01”). ASU No. 2019-01 clarifies the transition guidance related to interim disclosures provided in the year of adoption. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases, using classification criteria that are substantially similar to the previous guidance. For lessees, the recognition, measurement, and presentation of expenses and cash flows arising from a lease did not significantly changed from previous U.S. GAAP. The modified retrospective method includes several optional practical expedients that entities may elect to apply, as well as transition guidance specific to nonstandard leasing transactions. The Company adopted Topic 842 on January 1, 2019 using a cumulative-effect adjustment on the effective date of the standard, for which comparative periods are presented in accordance with the previous guidance under ASC 840. In adopting Topic 842, the Company elected to utilize the available package of practical expedients permitted under the transition guidance within the new standard, which does not require the reassessment of the following: i) whether existing or expired arrangements are or contain a lease; ii) the lease classification of existing or expired leases; and iii) whether previous initial direct costs would qualify for capitalization under the new lease standard. Additionally, the Company made an accounting policy election not to recognize assets or related lease liabilities with a lease term of twelve months or less in its condensed balance sheet. The adoption of this standard did not have an impact on the Company’s condensed balance sheet as all of the Company’s leases are for terms that are less than 12 months. Additionally, the adoption of the Standard did not have a material impact on the Company’s condensed statements of operations or condensed statements of cash flows. Recently Issued Accounting Pronouncements There have been no additional new accounting pronouncements or changes to accounting pronouncements during the three months ended March 31, 2019 that could be expected to materially impact the Company’s unaudited condensed financial statements.

LICENSE AGREEMENT	3 Months Ended
LICENSE AGREEMENT	Mar. 31, 2019
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. 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” and collectively with the 2016 Columbia Agreement and 2019 Columbia Agreement, the “Columbia Agreements”) 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. During the three months ended March 31, 2019 and 2018, the Company recorded $1,000 and $0.3 million, respectively, in research and development expense and $0.2 million and $19,000, respectively, in general and administrative expense related to the Columbia Agreements. In aggregate, the Company has incurred $1.6 million in expense from the execution of the Columbia Agreements through March 31, 2019. As of March 31, 2019, the Company had $0.3 million due to Columbia University included in accrued expenses and $9,000 included in accounts payable. As of December 31, 2018, the Company had $0.1 million due to Columbia University included in accrued expenses and $0.1 million included in accounts payable.

FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2019

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS

3. FAIR VALUE MEASUREMENTS

As of March 31, 2019 and December 31, 2018, the Company did not have financial assets or liabilities that are measured at fair value on a recurring basis.

During the three months ended March 31, 2018, the Company had Level 3 financial liabilities that were measured at fair value on a recurring basis. The Company's convertible promissory notes issued on February 5, 2018 (the "2018 Notes") (see Note 4), contained certain features which met the criteria to be bifurcated and accounted for separately from the 2018 Notes (the "Derivative Liability"). Also in connection with the issuance of the 2018 Notes, the Company had a contingent obligation to issue common stock warrants ("2018 Notes Warrants") upon the conversion of the 2018 Notes into Series B convertible preferred stock ("Series B Preferred Stock") (the "Warrant Liability"). The Derivative Liability and the Warrant Liability were initially recorded at fair value of $1.9 million and $0.1 million, respectively, and were subsequently remeasured at fair value at each reporting period.

The following table provides a roll forward of the aggregate fair values of the Derivative Liability and Warrant Liability as of March 31, 2018, for which fair value is determined using Level 3 inputs (in thousands):


	Derivative		Warrant
	Liability		Liability
Balance as of January 1, 2018	$	—	$	—
Initial fair value of Derivative Liability		1,896		—
Initial fair value of Warrant Liability		—		74
Change in fair value		180		6
Balance as of March 31, 2018	$	2,076	$	80

Changes in the fair value of the Derivative Liability and Warrant Liability were recognized in other income (expense), net in the condensed statement of operations.

CONVERTIBLE PROMISSORY NOTES	3 Months Ended
CONVERTIBLE PROMISSORY NOTES	Mar. 31, 2019
CONVERTIBLE PROMISSORY NOTES
CONVERTIBLE PROMISSORY NOTES	4. CONVERTIBLE PROMISSORY NOTES There were no convertible promissory notes outstanding as of March 31, 2019 and December 31, 2018. On February 5, 2018, the Company issued the 2018 Notes in the aggregate principal amount of $6.0 million. The 2018 Notes bore interest at a rate of 15.0% per annum, were unsecured and were due and payable, including accrued interest, on August 8, 2019. In the event of a qualified sale of preferred stock to one or more investors resulting in gross proceeds to the Company of at least $8.0 million, all principal and accrued and unpaid interest under the 2018 Notes was automatically convertible into a number of shares of the Company’s preferred stock issued in such a financing equal to the outstanding principal and accrued but unpaid interest under the 2018 Notes, divided by an amount equal to 80% of the lowest price per share of the preferred stock sold in the financing. In the event of a corporate transaction or change of control event, the 2018 Notes contained a put option whereby the Company was required to pay to the holders of 2018 Notes an amount equal to (i) the principal amount then outstanding under the 2018 Notes plus any accrued but unpaid interest, plus (ii) an amount equal to 30% of the outstanding principal amount. The terms of the 2018 Notes provided that: (i) all outstanding principal and interest was due and payable in cash upon an event of acceleration, as defined in the 2018 Notes agreement; (ii) amounts outstanding under the notes were not prepayable without the written consent of the holders of more than 50% of the outstanding principal of the notes, and in addition to the balance the Company will prepay, the Company will also pay the noteholders an amount equal to 15% of the principal amount of the notes that the Company is prepaying; and (iii) with respect to subordination, the Company has no outstanding indebtedness for borrowed money or any other liabilities, other than accounts payable arrangements with vendors entered into in the ordinary course of business and consistent with usual trade terms and will not issue or incur additional indebtedness for borrowed money while the 2018 Notes remain outstanding. There were no financial or negative covenants associated with the convertible promissory notes. The Derivative Liability represents the conversion feature in the event of a qualified financing and the put option, each of which met the definition of an embedded derivative and were required to be combined and accounted for as a separate unit of accounting. The Company recorded the issuance-date fair value of the Derivative Liability of $1.9 million as a debt discount and Derivative Liability in the Company’s balance sheet (see Note 3). In connection with the 2018 Notes, the Company paid legal costs and bank fees of $0.4 million and were obligated to issue the 2018 Notes Warrants (see Note 3 and Note 9) with an initial fair value of $0.1 million, which were capitalized and recorded as a debt discount. The debt discount, which included the Derivative Liability and 2018 Notes Warrants, was amortized at an effective interest rate of 54.9% using the effective interest method over the term of the loan. In connection with the 2018 Notes, the Company recognized interest expense of $0.3 million during the three months ended March 31, 2018. The interest expense includes amortization of the debt discount of $0.2 million for the three months ended March 31, 2018. In November 2018, in connection with the Company’s issuance and sale of Series B Preferred Stock, all of the then-outstanding principal and accrued interest under the 2018 Notes, totaling $6.6 million, was automatically converted into 1,097,721 shares of Series B Preferred Stock at a price equal to 80% of the $7.49 per share price paid by investors in the Series B Preferred Stock financing.

STOCK BASED COMPENSATION

3 Months Ended

Mar. 31, 2019

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION

7. STOCK‑BASED COMPENSATION

2016 Equity Incentive Plan

As of March 31, 2019, there were 2,966,241 shares reserved by the Company to grant under the 2016 Plan and an aggregate of 358,239 shares remained available for future grants.

Total stock-based compensation expense recorded for employees, directors and non-employees during the three months ended March 31, 2019 and 2018 was as follows (in thousands):


	Three Months Ended
	March 31,
	2019		2018
Research and development	$	147	$	13
General and administrative		178		13
Total stock-based compensation expense	$	325	$	26

During the three months ended March 31, 2019, the Company granted options to purchase 1,349,940 shares of common stock. The Company recorded stock-based compensation expense for options granted during the three months ended March 31, 2019 of $0.2 million. As of March 31, 2019, there were 2,552,921 options outstanding. The weighted‑average fair value of options granted during the three months ended March 31, 2019 was $3.15 per share. As of March 31, 2019, the total unrecognized stock‑based compensation balance for unvested options was $5.3 million, which is expected to be recognized over 2.3 years.

Stock Options Granted to Employees that Contain Service, Performance and Market Conditions

Included in the stock options granted during the three months ended March 31, 2019 were 159,501 stock options that contain service-, performance- and market-based vesting conditions 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:


	March 31,
	2019
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 are recognized over the derived service period, or when the vesting condition is met if earlier. The Company recorded $0.1 million in compensation expense related to these awards for the three months ended March 31, 2019.

STOCKHOLDERS' EQUITY

3 Months Ended

Mar. 31, 2019

STOCKHOLDERS’ EQUITY

STOCKHOLDERS’ EQUITY

8. STOCKHOLDERS’ EQUITY

Common Stock

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.

Preferred Stock

In February 2019, the Company issued 442,925 shares of Series B Preferred Stock at $7.49 per share for gross proceeds of approximately $3.3 million. Issuance costs were $0.3 million, which included the obligation to issue warrants to purchase common stock (see Note 9). As of March 31, 2019 and December 31, 2018, Series A convertible preferred stock (“Series A Preferred Stock”) and Series B Preferred Stock (collectively, “Preferred Stock”) consisted of the following (in thousands, except share data):


	As of March 31, 2019
		Preferred
	Preferred	Stock Issued					Common Stock
	Stock	and	Carrying		Liquidation		Issuable Upon
	Authorized	Outstanding	Value		Value		Conversion
Series A Preferred Stock	3,093,898	3,093,898	$	6,254	$	7,000	3,093,898
Series B Preferred Stock	7,790,052	4,444,773		32,207	$	33,281	4,444,773
Total	10,883,950	7,538,671	$	38,461	$	40,281	7,538,671


	As of December 31, 2018
		Preferred
	Preferred	Stock Issued					Common Stock
	Stock	and	Carrying		Liquidation		Issuable Upon
	Authorized	Outstanding	Value		Value		Conversion
Series A Preferred Stock	3,093,898	3,093,898	$	6,254	$	7,000	3,093,898
Series B Preferred Stock	7,790,052	4,001,848		29,156		29,964	4,001,848
Total	10,883,950	7,095,746	$	35,410	$	36,964	7,095,746

The following is a summary of the rights and privileges of the common and preferred stockholders as of March 31, 2019:

Voting

The holders of Preferred Stock have the right to one vote for each share of common stock into which such Preferred Stock could be converted and will vote together with the holders of common stock as a single class.

Dividends

Dividends are payable to holders of Preferred Stock prior to payment of any dividend to holders of common stock. Dividends are payable when and if declared out of funds legally available and such dividends are not cumulative. In the event the board of directors (the “Board”) of the Company declares a dividend payable on the common stock, the holders of the Preferred Stock would be entitled to receive the amount of dividends per share of Preferred Stock that would be payable on the number of whole shares of the common stock into which each share of such Preferred Stock held by each holder could be converted into.

Liquidation

In the event of any liquidation, dissolution or winding up of the Company, or a Deemed Liquidation Event (as defined below), the holders of shares of Preferred Stock then outstanding are entitled to be paid out of the assets of the Company available for distribution to its stockholders before any payment shall be made to the holders of common stock by reason of their ownership thereof, in an amount per share equal to the greater of (i) the original issue price ($2.26 per share for Series A Preferred Stock and $7.49 per share for Series B Preferred Stock) plus any dividends declared but unpaid thereon or (ii) such amount per share as would have been payable had each series of Preferred Stock been converted into common stock immediately prior to a liquidation, dissolution or winding up of the Company or Deemed Liquidation Event. If upon any such liquidation, dissolution or winding up of the Company or Deemed Liquidation Event, the proceeds shall be insufficient to pay the holders of shares of Preferred Stock the full amount to which they shall be entitled, the holders of shares of Preferred Stock shall share ratably in any distribution of the proceeds in proportion to the respective amounts which would otherwise be payable in respect of the shares of Preferred Stock held by them upon such distribution if all amounts payable with respect to such shares were paid in full. After the payment of all preferential amounts to be paid to the holders of shares of Preferred Stock, the remaining proceeds shall be distributed among the holders of shares of common stock pro rata based on the number of shares held by each such holder.

A Deemed Liquidation Event is defined as: (i) a merger where the Company is a constituent party or a subsidiary of the Company is a constituent party and the Company issues shares of its capital stock pursuant to such merger or consolidation, except any such merger or consolidation involving the Company or a subsidiary in which the shares of capital stock of the Company outstanding immediately prior to such merger or consolidation continue to represent, or are converted into or exchanged for shares of capital stock that represent, immediately following such merger or consolidation, at least a majority, by voting power, of the capital stock of (1) the surviving or resulting corporation or (2) if the surviving or resulting corporation is a wholly owned subsidiary of another corporation immediately following such merger or consolidation, the parent corporation of such surviving or resulting corporation; or (ii) the sale, lease, transfer, exclusive license or other disposition, in a single transaction or series of related transactions, by the Company or any subsidiary of the Company of all or substantially all the assets of the Company and its subsidiaries taken as a whole, or the sale or disposition (whether by merger or otherwise) of one or more subsidiaries of the Company if substantially all of the assets of the Company and its subsidiaries taken as a whole are held by such subsidiary or subsidiaries, except where such sale, lease, transfer, exclusive license or other disposition is to a wholly owned subsidiary of the Company.

Protective Provisions

At any time when any shares of Preferred Stock remain outstanding, the Company shall not take any of the following actions without the vote or written consent of the holders of a majority of the then outstanding shares of Preferred Stock separately as a class: (i) liquidate, dissolve or wind-up the business and affairs of the Company, effect any merger, consolidation or any other Deemed Liquidation Event, or consent to any of the foregoing, in each case other than in the event that such event would provide the holders of the Preferred Stock a return per each share of Preferred Stock, including all distributions and dividends paid to such holders prior to such event by the Company, if any, of at least two (2) times the Series B original issue price in the twenty-four (24) months following the Series B original issue date (November 5, 2018) or three (3) times the Series B original issue price thereafter; (ii) amend, alter, or repeal any provision of the Certificate of Incorporation or the Company’s bylaws in a manner that adversely affects the powers, preferences or rights of the Preferred Stock; (iii) create, or authorize the creation of, or issue or obligate itself to issue shares of, any additional class or series of capital stock unless the same ranks junior to the Preferred Stock with respect to the distribution of assets on the liquidation, dissolution or winding up of the Company, the payment of dividends and rights of redemption, or increase the authorized number of shares of Preferred Stock; (iv) purchase or redeem (or permit any subsidiary to purchase or redeem) or pay or declare any dividend or make any distribution on, any shares of capital stock of the Company other than (a) redemptions of or dividends or distributions on the Preferred Stock as expressly authorized herein, (b) dividends or other distributions payable on the common stock solely in the form of additional shares of common stock and (c) repurchases of stock from former employees, officers, directors, consultants or other persons who performed services for the Company or any subsidiary in connection with the cessation of such employment or service at the lower of the original purchase price or the then-current fair market value thereof; (v) create, or authorize the creation of, or issue, or authorize the issuance of any debt security, or permit any subsidiary to take any such action with respect to any debt security, if the aggregate indebtedness of the Company and its subsidiaries for borrowed money following such action would exceed $2.0 million other than equipment leases or bank lines of credit; (vi) create, or hold capital stock in, any subsidiary that is not wholly owned (either directly or through one or more other subsidiaries) by the Company, or sell, transfer or otherwise dispose of any capital stock of any direct or indirect subsidiary of the Company, or permit any direct or indirect subsidiary to sell, lease, transfer, exclusively license or otherwise dispose (in a single transaction or series of related transactions) of all or substantially all of the assets of such subsidiary; or (vi) increase or decrease the authorized number of directors of the Company.

Optional Conversion Rights

Each share of Preferred Stock is convertible, at the option of the holder thereof, at any time and from time to time after issuance, and without the payment of additional consideration into such number of fully paid and nonassessable shares of common stock as is determined by dividing the original issue price ($2.26 per share for Series A Preferred Stock and $7.49 per share for Series B Preferred Stock) by the series conversion price ($2.26 per share for Series A Preferred Stock and $7.49 per share for Series B Preferred Stock) in effect at the time of conversion. As of March 31, 2019, the Preferred Stock is convertible into common stock on a one-for-one basis.

Mandatory Conversion Rights

All outstanding shares of Preferred Stock shall automatically be converted into shares of common stock, at the then effective conversion rate, upon either (a) the closing of the sale of shares of common stock to the public in a firm-commitment underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, as amended, resulting in at least $30.0 million of proceeds, net of the underwriting discount and commissions, to the Company, or (b) the date and time, or the occurrence of an event, specified by vote or written consent of the holders of at least a majority of the then outstanding shares of Preferred Stock.

Redemption

The Preferred Stock is redeemable upon the occurrence of a Deemed Liquidation Event, which is not solely in control of the Company. Therefore, the Preferred Stock has been classified as temporary equity.

WARRANTS

3 Months Ended

Mar. 31, 2019

WARRANTS

WARRANTS

9. WARRANTS

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 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 (see Note 4). 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.

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 (see Note 8). 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 was estimated using the Black‑Scholes option pricing model with the following assumptions:


Contractual term (in years)	10.0
Volatility	74.48	%
Risk-free interest rate	3.20	%
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 equity‑classified 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 (see Note 8). 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.

NET LOSS PER COMMON SHARE

3 Months Ended

Mar. 31, 2019

NET LOSS PER COMMON SHARE

NET LOSS PER COMMON SHARE

11. 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 three months ended March 31, 2019 and 2018, 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):


	Three Months Ended
	March 31,
	2019		2018
Numerator:
Net loss	$	(8,730)	$	(2,335)
Denominator:
Weighted-average common stock outstanding		5,513,531		5,458,450
Net loss per share, basic and diluted	$	(1.58)	$	(0.43)

The Company’s potentially dilutive securities, which include Preferred Stock, 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 March 31, 2019 and 2018, 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
	March 31,
	2019	2018
Preferred Stock	7,538,671	3,093,898
Options to purchase common stock	2,552,921	1,030,825
Warrants to purchase common stock	482,364	309,389

SUBSEQUENT EVENTS	3 Months Ended
SUBSEQUENT EVENTS	Mar. 31, 2019
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	12. SUBSEQUENT EVENTS 2019 Equity Incentive Plan In May 2019, the Company’s Board adopted its 2019 Equity Incentive Plan (“2019 Plan”), which was subsequently approved by its stockholders and became effective on May 13, 2019. Initially, 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 (1) 1,618,841 new shares, plus (2) the number of shares (not to exceed 2,911,159 shares) (i) that remained available for the issuance of awards under the 2016 Equity Incentive Plan, as amended (“2016 Plan”), at the time the 2019 Plan became effective, and (ii) any shares subject to outstanding options or other share awards that were granted under the 2016 Plan that terminate, expire or are otherwise forfeited, reacquired or withheld. 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. Stock Option Grants In May 2019, in conjunction with the IPO, the Board granted stock options to purchase an aggregate of 971,975 shares of common stock to executive officers and 81,840 shares of common stock to non-employee directors with an exercise price of $10.00 per share. In June 2019, the Board granted a stock option to purchase 20,460 shares of common stock with an exercise price of $10.02 per share to Mr. Funtleyder upon his transition to a non-employee director of the Board. All of the options were issued pursuant to the 2019 Plan. The options granted to executives will vest 25% on the first anniversary of their grant date and the remaining shares will vest in 36 equal monthly installments thereafter, subject to the executive officer's continuous employment. The options granted to non-employee directors will vest in 36 equal monthly installments, subject to the director's continuous service as director. 2019 Employee Stock Purchase Plan In May 2019, the Company’s Board adopted its 2019 Employee Stock Purchase Plan (“2019 ESPP”), which was subsequently approved by its stockholders and became effective on May 13, 2019. The 2019 ESPP authorizes the initial issuance of up to a total of 180,000 shares of the Company’s common stock to participating employees. The 2019 ESPP provides that the number of shares reserved and available for issuance under the 2019 ESPP will automatically increase each January 1, beginning on January 1, 2020, by (i) 1% of the outstanding number of shares of common stock on the immediately preceding December 31; (ii) 360,000 shares or (iii) such lesser number of shares as determined by the Board. The Board or the Compensation Committee of the Board may from time to time determine the length and duration of the offering periods pursuant to the 2019 ESPP. As of March 31, 2019, no offering periods have been approved. Modification of Certain Stock Option Grants In April 2019, the Board approved a modification to the vesting conditions of certain outstanding stock option grants to certain employees and directors. The Company is evaluating the impact this modification will have to its second quarter financial statements. Separation Agreement with the Former Interim Chief Financial Officer In May 2019, the Company and its former interim Chief Financial Officer entered into a separation agreement, the terms of which provide that the former interim Chief Financial Officer receive certain severance benefits and acceleration of the vesting of options to purchase 79,752 shares of common stock held by the former interim Chief Financial Officer. The Company is currently evaluating the impact of this acceleration will have to its second quarter financial statements.

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2019
ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Accounting	The accompanying unaudited condensed financial statements as of March 31, 2019 and for the three months ended March 31, 2019 and 2018 have been prepared by the Company in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate. These condensed financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2018 included in the Company’s final prospectus that forms a part of the Company’s Registration Statement on Form S-1 (Reg. No. 333-230838), filed with the SEC pursuant to Rule 424(b)(4) on May 14, 2019 (the “Prospectus”). The unaudited condensed financial statements have been prepared on the same basis as the audited financial statements. In the opinion of management, the accompanying unaudited condensed financial statements contain all adjustments which are necessary for a fair presentation of the Company’s financial position as of March 31, 2019, results of operations for the three months ended March 31, 2019 and 2018 and cash flows for the three months ended March 31, 2019 and 2018. Such adjustments are of a normal and recurring nature. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2019.
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.
Stock-Based Compensation	Stock‑Based Compensation The Company accounts for its stock-based compensation as expense in the condensed 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 with the exception of stock options that also include service, performance and market conditions, which are valued using the Monte-Carlo simulation 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. A Monte-Carlo simulation is an analytical method used to estimate fair value by performing a large number of simulations or trial runs and thereby determining a value based on the possible outcomes from these trial runs based on the specific vesting conditions. The fair value of stock-based payments is recognized as expense over the requisite service period which is generally the vesting period, with the exception of the fair value of stock-based payments for awards that also include service, performance and market conditions, which is recognized as expense over the derived service period determined using the Monte-Carlo simulation.
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 convertible preferred stock and 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. The Company recorded deferred offering costs related to the IPO of $1.5 million as of March 31, 2019 in prepaid expenses and other current assets. Upon closing the IPO in May 2019, deferred offering costs were reclassified from prepaid and other current assets and recorded against the IPO proceeds reducing additional paid-in capital.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements The new accounting pronouncements recently adopted by the Company are described in the Company’s audited financial statements as of and for the year ended December 31, 2018, and the notes thereto, which are included in the Company’s Prospectus as filed with the SEC on May 14, 2019. Except as described below, there have been no new accounting pronouncements adopted by the Company during the three months ended March 31, 2019. In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases on their balance sheet date (“ASU No. 2016-02”). ASU No. 2016-02 is effective for fiscal years beginning after December 15, 2018. In July 2018, an amendment was made that allows companies the option of using the effective date of the new standard as the initial application date (at the beginning of the period in which the new standard is adopted, rather than at the beginning of the earliest comparative period). This update includes a short-term lease exception for leases with a term of 12 months or less, in which a lessee can make an accounting policy election not to recognize the associated lease assets and lease liabilities on its balance sheet. Additionally, in March 2019, the FASB issued ASU 2019-01, Leases (Topic 842): Codification Improvements (“ASU No. 2019-01”). ASU No. 2019-01 clarifies the transition guidance related to interim disclosures provided in the year of adoption. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases, using classification criteria that are substantially similar to the previous guidance. For lessees, the recognition, measurement, and presentation of expenses and cash flows arising from a lease did not significantly changed from previous U.S. GAAP. The modified retrospective method includes several optional practical expedients that entities may elect to apply, as well as transition guidance specific to nonstandard leasing transactions. The Company adopted Topic 842 on January 1, 2019 using a cumulative-effect adjustment on the effective date of the standard, for which comparative periods are presented in accordance with the previous guidance under ASC 840. In adopting Topic 842, the Company elected to utilize the available package of practical expedients permitted under the transition guidance within the new standard, which does not require the reassessment of the following: i) whether existing or expired arrangements are or contain a lease; ii) the lease classification of existing or expired leases; and iii) whether previous initial direct costs would qualify for capitalization under the new lease standard. Additionally, the Company made an accounting policy election not to recognize assets or related lease liabilities with a lease term of twelve months or less in its condensed balance sheet. The adoption of this standard did not have an impact on the Company’s condensed balance sheet as all of the Company’s leases are for terms that are less than 12 months. Additionally, the adoption of the Standard did not have a material impact on the Company’s condensed statements of operations or condensed statements of cash flows. Recently Issued Accounting Pronouncements There have been no additional new accounting pronouncements or changes to accounting pronouncements during the three months ended March 31, 2019 that could be expected to materially impact the Company’s unaudited condensed financial statements.

FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2018

FAIR VALUE MEASUREMENTS

Schedule of Company’s Derivative Liability and Warrant Liability


	Derivative		Warrant
	Liability		Liability
Balance as of January 1, 2018	$	—	$	—
Initial fair value of Derivative Liability		1,896		—
Initial fair value of Warrant Liability		—		74
Change in fair value		180		6
Balance as of March 31, 2018	$	2,076	$	80

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)

3 Months Ended

Mar. 31, 2019

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):


	March 31,		December 31,
	2019		2018
Deferred offering costs	$	1,452	$	310
Prepaid research and development expenses		546		1,044
Prepaid rent expense		76		65
Prepaid insurance expense		26		1
Other prepaid expenses and other current assets		86		78
Total prepaid expenses and other current assets	$	2,186	$	1,498

STOCK BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2019

STOCK BASED COMPENSATION

Schedule of stock-based compensation expenses

Total stock-based compensation expense recorded for employees, directors and non-employees during the three months ended March 31, 2019 and 2018 was as follows (in thousands):


	Three Months Ended
	March 31,
	2019		2018
Research and development	$	147	$	13
General and administrative		178		13
Total stock-based compensation expense	$	325	$	26

Schedule of valuation assumptions


	March 31,
	2019
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

STOCKHOLDER EQUITY (Tables)

3 Months Ended

Mar. 31, 2019

STOCKHOLDER EQUITY

Summary of Preferred Stock

As of March 31, 2019 and December 31, 2018, Series A convertible preferred stock (“Series A Preferred Stock”) and Series B Preferred Stock (collectively, “Preferred Stock”) consisted of the following (in thousands, except share data):


	As of March 31, 2019
		Preferred
	Preferred	Stock Issued					Common Stock
	Stock	and	Carrying		Liquidation		Issuable Upon
	Authorized	Outstanding	Value		Value		Conversion
Series A Preferred Stock	3,093,898	3,093,898	$	6,254	$	7,000	3,093,898
Series B Preferred Stock	7,790,052	4,444,773		32,207	$	33,281	4,444,773
Total	10,883,950	7,538,671	$	38,461	$	40,281	7,538,671


	As of December 31, 2018
		Preferred
	Preferred	Stock Issued					Common Stock
	Stock	and	Carrying		Liquidation		Issuable Upon
	Authorized	Outstanding	Value		Value		Conversion
Series A Preferred Stock	3,093,898	3,093,898	$	6,254	$	7,000	3,093,898
Series B Preferred Stock	7,790,052	4,001,848		29,156		29,964	4,001,848
Total	10,883,950	7,095,746	$	35,410	$	36,964	7,095,746

WARRANTS (Tables)

3 Months Ended

Mar. 31, 2019

2018 Warrants

Class of Warrant or Right [Line Items]

Schedule of fair value of warrants issued is estimated using the Black Scholes option pricing model

The fair value of the 2018 Warrants was estimated using the Black‑Scholes option pricing model with the following assumptions:


Contractual term (in years)	10.0
Volatility	74.48	%
Risk-free interest rate	3.20	%
Dividend yield	0.00	%

2019 Warrants

Class of Warrant or Right [Line Items]

Schedule of fair value of warrants issued is estimated using the Black Scholes option pricing model

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	%

NET LOSS PER COMMON SHARE (Tables)

3 Months Ended

Mar. 31, 2019

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):


	Three Months Ended
	March 31,
	2019		2018
Numerator:
Net loss	$	(8,730)	$	(2,335)
Denominator:
Weighted-average common stock outstanding		5,513,531		5,458,450
Net loss per share, basic and diluted	$	(1.58)	$	(0.43)

Schedule of potential dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders


	As of
	March 31,
	2019	2018
Preferred Stock	7,538,671	3,093,898
Options to purchase common stock	2,552,921	1,030,825
Warrants to purchase common stock	482,364	309,389

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - IPO (Details) $ / shares in Units, $ in Millions		3 Months Ended
	May 16, 2019 shares	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 shares
IPO
Convertible preferred stock, outstanding (in shares)		7,538,671	7,095,746
IPO
IPO
Shares issued (in shares)		4,000,000
Issue price (in dollars per share) \| $ / shares		$ 10.00
Aggregate gross proceeds from issuance \| $		$ 40.0
Net proceeds after deducting underwriting discounts and commissions and estimated offering costs \| $		$ 34.0
Stock split ratio		55.2486
Number of shares into which convertible preferred stock is converted	7,538,671
Number of shares issued for each share of convertible preferred stock converted	1
Convertible preferred stock, outstanding (in shares)	0

LICENSE AGREEMENT (Details)	1 Months Ended			3 Months Ended		30 Months Ended
LICENSE AGREEMENT (Details)	Mar. 31, 2019 USD ($) item	Jan. 31, 2019 USD ($)	Oct. 31, 2016 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Agreements
Research and development				$ 6,874,000	$ 1,448,000
General and administrative				1,855,000	420,000
Operating expenses				8,729,000	1,868,000
Accrued expenses and other current liabilities	$ 3,679,000			3,679,000		$ 3,679,000	$ 1,413,000
Accounts payable	2,649,000			2,649,000		2,649,000	3,015,000
Columbia University
Agreements
Research and development				1,000	300,000
General and administrative				200,000	$ 19,000
Operating expenses						1,600,000
Accrued expenses and other current liabilities	300,000			300,000		300,000	100,000
Accounts payable	$ 9,000			$ 9,000		$ 9,000	$ 100,000
2016 license agreement \| Columbia University
Agreements
Percentage of outstanding common stock issued			5.00%
Fair value of stock issued			$ 500,000
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 research agreement
Agreements
Agreement term	12 months
Written notice period for termination of agreement	30 days
Number of parts \| item	2
2019 research agreement - Part I
Agreements
Agreement term	6 months
Payment to be made	$ 100,000
2019 research agreement - Part II
Agreements
Agreement term	6 months
Payment to be made	$ 200,000
Minimum \| 2016 license agreement \| Columbia University
Agreements
Percentage of sublicensing revenue, if sublicenses rights granted			10.00%
Minimum \| 2019 license agreement \| Columbia University
Agreements
Percentage of sublicensing revenue, if sublicenses rights granted		10.00%
Maximum \| 2016 license agreement \| Columbia University
Agreements
Payment on achievement of specified development and regulatory milestones			$ 1,300,000
Payment on achievement of specified level of aggregate annual net sales			$ 1,000,000
Percentage of sublicensing revenue, if sublicenses rights granted			20.00%
Maximum \| 2019 license agreement \| Columbia University
Agreements
Payment on achievement of specified development and regulatory milestones		$ 1,300,000
Payment on achievement of specified level of aggregate annual net sales		$ 1,000,000
Percentage of sublicensing revenue, if sublicenses rights granted		50.00%

CONVERTIBLE PROMISSORY NOTES (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended
	Feb. 05, 2018	Nov. 30, 2018	Mar. 31, 2019	Feb. 28, 2019	Dec. 31, 2018	Jan. 18, 2018
Debt
Outstanding principal and accrued interest			$ 0		$ 0
Fair value of derivative liability	$ 1,900
Series B Convertible Preferred Stock
Debt
Issue price (in dollars per share)		$ 7.49	$ 7.49	$ 7.49
Warrants Issued with the 2018 Notes
Debt
Initial fair value recorded as debt discount (in dollars)						$ 100
2018 Notes
Debt
Outstanding principal and accrued interest		$ 6,600
Aggregate principal amount	$ 6,000
Interest rate (as a percent)	15.00%
Threshold proceeds from sale of preferred stock	$ 8,000
Preferred stock conversion price as a percentage of lowest price per share of preferred stock sold in financing	80.00%	80.00%
Percentage of outstanding principal amount payable in event of corporate transaction or change of control event	30.00%
Minimum percentage of outstanding principal amount written consent required for prepayment	50.00%
Additional percentage of outstanding principal payable on prepayment	15.00%
Legal costs and bank fees	$ 400
Effective interest rate (as a percent)	54.90%
Interest expense	$ 300
Amortization of debt discount	200
Debt converted into shares		1,097,721
2018 Notes \| Derivative Liability
Debt
Initial fair value recorded as debt discount (in dollars)	$ 1,900

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
PREPAID EXPENSES AND OTHER CURRENT ASSETS
Deferred offering costs	$ 1,452	$ 310
Prepaid research and development expenses	546	1,044
Prepaid rent expense	76	65
Prepaid insurance expense	26	1
Other prepaid expenses and other current assets	86	78
Total prepaid expenses and other current assets	$ 2,186	$ 1,498

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES
Accrued pre-clinical and clinical expenses	$ 2,007	$ 865
Accrued professional fees	1,105	312
Accrued compensation and benefits	129	56
Accrued patent expenses	300	126
Other	138	54
Total accrued expenses and other current liabilities	$ 3,679	$ 1,413

STOCK BASED COMPENSATION - Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock-based compensation
Options granted (in shares)	1,349,940
Stock-based compensation expense	$ 325	$ 26
Options outstanding (in shares)	2,552,921
Weighted-average fair value of options granted	$ 3.15
Unrecognized stock-based compensation balance for unvested options	$ 5,300
Unrecognized stock-based compensation balance for unvested options expected to be recognized (in years)	2 years 3 months 18 days
Options \| Awards granted during the three months ended March 31, 2019
Stock-based compensation
Stock-based compensation expense	$ 200

STOCK BASED COMPENSATION - Options that Contain Service, Performance and Market Conditions Options (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock-based compensation
Options granted (in shares)	1,349,940
Stock-based compensation expense	$ 325	$ 26
Stock Options that Contain Service, Performance and Market Conditions
Stock-based compensation
Options granted (in shares)	159,501
Fair value at grant date	$ 500
Stock Options that Contain Service, Performance and Market Conditions \| Minimum
Stock-based compensation
Derived service period	P1D
Stock Options that Contain Service, Performance and Market Conditions \| Maximum
Stock-based compensation
Derived service period	P3Y

STOCK BASED COMPENSATION - Valuation assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Valuation Assumptions
Stock-based compensation expense	$ 325	$ 26
Options
Valuation Assumptions
Dividend yield (as a percent)	0.00%
Options \| Awards granted during the three months ended March 31, 2019
Valuation Assumptions
Stock-based compensation expense	$ 200
Stock Options that Contain Service, Performance and Market Conditions
Valuation Assumptions
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 Options that Contain Service, Performance and Market Conditions \| Awards granted during the three months ended March 31, 2019
Valuation Assumptions
Stock-based compensation expense	$ 100

STOCKHOLDER EQUITY - Preferred stock summary (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Preferred Stock
Preferred Stock Authorized	10,883,950	10,883,950
Preferred Stock Outstanding	7,538,671	7,095,746
Carrying Value	$ 38,461	$ 35,410
Liquidation Value	$ 40,281	$ 36,964
Common Stock Issuable Upon Conversion	7,538,671	7,095,746
Series A Convertible Preferred Stock
Preferred Stock
Preferred Stock Authorized	3,093,898	3,093,898
Preferred Stock Issued	3,093,898	3,093,898
Preferred Stock Outstanding	3,093,898	3,093,898	3,093,898	3,093,898
Carrying Value	$ 6,254	$ 6,254	$ 6,254	$ 6,254
Liquidation Value	$ 7,000	$ 7,000
Common Stock Issuable Upon Conversion	3,093,898	3,093,898
Series B Convertible Preferred Stock
Preferred Stock
Preferred Stock Authorized	7,790,052	7,790,052
Preferred Stock Issued	4,444,773	4,001,848
Preferred Stock Outstanding	4,444,773	4,001,848
Carrying Value	$ 32,207	$ 29,156
Liquidation Value	$ 33,281	$ 29,964
Common Stock Issuable Upon Conversion	4,444,773	4,001,848

STOCKHOLDER EQUITY - Preferred stock other information (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) Vote $ / shares	Feb. 28, 2019 $ / shares	Nov. 30, 2018 $ / shares
Preferred Stock
Number of votes for each share of common stock into which temporary equity could be converted \| Vote	1
Threshold debt obligations \| $	$ 2.0
Conversion ratio (as a percent)	100.00%
Minimum proceeds from conversion of preferred stock if converted \| $	$ 30.0
Series A Convertible Preferred Stock
Preferred Stock
Original issue price (in dollars per share)	$ 2.26
Stock conversion price (in dollars per share)	$ 2.26
Series B Convertible Preferred Stock
Preferred Stock
Dividend multiple to be paid within twenty-four months following the original issue date	2
Dividend multiple to be paid thereafter following the original issue date	3
Original issue price (in dollars per share)	$ 7.49	$ 7.49	$ 7.49
Stock conversion price (in dollars per share)	$ 7.49

WARRANTS - Issued with the 2018 Notes (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Nov. 05, 2018	Mar. 31, 2019	Jan. 18, 2018
Warrants
Warrants to purchase common stock (in dollars)		$ 80
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 - Issued with Series B Preferred Stock (Details) $ / shares in Units, $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended
	Feb. 28, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2019 USD ($) Y Rate
Warrants
Warrants to purchase common stock (in dollars) \| $			$ 80
Warrants Issued with Series B Preferred Stock
Warrants
Warrants to purchase common stock (in shares) \| shares	23,867	72,261
Warrants to purchase common stock (in dollars) \| $	$ 100	$ 200
Exercise price (in dollars per share) \| $ / shares	$ 8.24	$ 8.24
Expiration term	10 years	10 years
2018 Warrants \| Contractual term (in years)
Warrants
Measurement input \| Y			10.0
2018 Warrants \| Volatility
Warrants
Measurement input			0.7448
2018 Warrants \| Risk-free interest rate
Warrants
Measurement input			0.0320
2018 Warrants \| Dividend yield
Warrants
Measurement input			0.0000
2019 Warrants \| Contractual term (in years)
Warrants
Measurement input \| Y			10.00
2019 Warrants \| Volatility
Warrants
Measurement input			0.7322
2019 Warrants \| Risk-free interest rate
Warrants
Measurement input			0.0270
2019 Warrants \| Dividend yield
Warrants
Measurement input			0.0000

NET LOSS PER COMMON SHARE - EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net loss attributable to common stockholders—basic	$ (8,730)	$ (2,335)
Net loss attributable to common stockholders— diluted	$ (8,730)	$ (2,335)
Denominator:
Weighted-average common stock outstanding	5,513,531	5,458,450
Net loss per share, basic and diluted	$ (1.58)	$ (0.43)

SUBSEQUENT EVENTS (Details)	1 Months Ended		3 Months Ended
SUBSEQUENT EVENTS (Details)	Jun. 30, 2019 $ / shares shares	May 31, 2019 installment $ / shares shares	Mar. 31, 2019 shares
Subsequent event
Stock option granted (in shares)			1,349,940
Subsequent Event \| Tranche one
Subsequent event
Vesting percentage		25.00%
Subsequent Event \| Executive officers
Subsequent event
Stock option granted (in shares)		971,975
Exercise price per share (in dollars per share) \| $ / shares		$ 10.00
Subsequent Event \| Executive officers \| Tranche two
Subsequent event
Number of equal monthly installments in which shares will vest \| installment		36
Subsequent Event \| Non-employee directors
Subsequent event
Stock option granted (in shares)		81,840
Exercise price per share (in dollars per share) \| $ / shares		$ 10.00
Number of equal monthly installments in which shares will vest \| installment		36
Subsequent Event \| Mr. Funtleyder
Subsequent event
Stock option granted (in shares)	20,460
Exercise price per share (in dollars per share) \| $ / shares	$ 10.02
Subsequent Event \| Former Interim Chief Financial Officer \| Separation agreement
Subsequent event
Number of options receiving accelerated vesting		79,752
Subsequent Event \| 2019 Plan
Subsequent event
Shares reserved (in shares)		4,530,000
New shares authorized (in shares)		1,618,841
Maximum number of shares available for issuance from previous plan		2,911,159
Increase in number of shares reserved and available for issuance (as a percent)		5.00%
Subsequent Event \| 2019 ESPP
Subsequent event
New shares authorized (in shares)		360,000
Increase in number of shares reserved and available for issuance (as a percent)		1.00%
Shares authorized (in shares)		180,000

Condensed Statements of Cash Flows (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Condensed Statement of Cash Flows
Issuance costs of convertible preferred stock	$ 186
Debt issuance cost	$ 440

INCOME TAXES	3 Months Ended
INCOME TAXES	Mar. 31, 2019
INCOME TAXES
INCOME TAXES	10. INCOME TAXES During the three months ended March 31, 2019 and the year ended December 31, 2018, the Company recorded a full valuation allowance on federal and state deferred tax assets since management does not forecast the Company to be in a profitable position in the near future.

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Offering Costs (Details) $ in Millions	Mar. 31, 2019 USD ($)
Deferred offering cost
Deferred offering costs	$ 1.5

FAIR VALUE MEASUREMENTS - Initial FV (Details) $ in Millions	Feb. 05, 2018 USD ($)
Derivative Liability
Fair value of derivative liability	$ 1.9
Warrant Liability
Warrant Liability	$ 0.1

FAIR VALUE MEASUREMENTS - Level 3 inputs (Details)	3 Months Ended
FAIR VALUE MEASUREMENTS - Level 3 inputs (Details)	Mar. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Recurring Basis, Unobservable Input Reconciliation, Liability, Gain (Loss), Statement of Income	us-gaap:NonoperatingIncomeExpense

ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Liquidity (Details)	3 Months Ended
	Mar. 31, 2019
Liquidity
Substantial Doubt about Going Concern, within One Year	false

STOCK BASED COMPENSATION - 2016 Plan (Details) - 2016 Plan	Mar. 31, 2019 shares
Stock-based compensation
Shares reserved (in shares)	2,966,241.0
Remained available for future grants (in shares)	358,239.0

STOCKHOLDERS' EQUITY - Common Stock (Details)	3 Months Ended
STOCKHOLDERS' EQUITY - Common Stock (Details)	Mar. 31, 2019 Vote
Common Stock Par value $0.0001
STOCKHOLDERS' EQUITY
Number of votes per common stock	1