Y-mAbs Therapeutics (YMAB) 10-K 12 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 10, 2020	Jun. 30, 2019
Document and Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity Registrant Name	Y-mAbs Therapeutics, Inc.
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Public Float			$ 295.6
Entity Common Stock, Shares Outstanding		39,756,694
Entity Central Index Key	0001722964
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
CURRENT ASSETS
Cash and cash equivalents	$ 207,136	$ 147,840
Restricted cash		31
Other current assets	4,819	3,661
Total current assets	211,955	151,532
Property and equipment, net	2,052	205
Operating lease right-of-use assets	1,989
Other assets	370	187
TOTAL ASSETS	216,366	151,924
LIABILITIES
Accounts payable	8,520	5,872
Accrued liabilities	4,550	3,251
Operating lease liabilities, current portion	516
Total current liabilities	13,586	9,123
Accrued milestone and royalty payments	1,921	2,050
Operating lease liabilities, long-term portion	1,714
Other liabilities	242	224
TOTAL LIABILITIES	17,463	11,397
Commitments and contingencies (Note 6)
STOCKHOLDERS? EQUITY
Preferred stock, $0.0001 par value, 5,500,000 shares authorized at December 31, 2019 and December 31, 2018; none issued at December 31, 2019 and December 31, 2018
Common stock, $0.0001 par value, 100,000,000 shares authorized at December 31, 2019 and December 31, 2018; 39,728,416 and 34,193,666 shares issued at December 31, 2019 and December 31, 2018, respectively	4	3
Additional paid in capital	364,712	225,352
Accumulated other comprehensive income	50	7
Accumulated deficit	(165,863)	(84,835)
TOTAL STOCKHOLDERS' EQUITY	198,903	140,527
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 216,366	$ 151,924

Consolidated Balance Sheets (pa

Consolidated Balance Sheets (parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized shares	5,500,000	5,500,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized shares	100,000,000	100,000,000
Common stock, shares issued	39,728,416	34,193,666

Consolidated Statements of Net

Consolidated Statements of Net Loss and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
OPERATING EXPENSES
Research and development	$ 63,492	$ 34,269
General and administrative	19,512	8,961
Total operating expenses	83,004	43,230
Loss from operations	(83,004)	(43,230)
OTHER INCOME/(EXPENSES)
Interest and other income/(expenses)	1,976	(44)
NET LOSS	(81,028)	(43,274)
Other comprehensive income
Foreign currency translation	43	175
COMPREHENSIVE LOSS	$ (80,985)	$ (43,099)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.30)	$ (1.50)
Weighted average common shares outstanding, basic and diluted	35,183,488	28,772,384

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income/(Loss)	Accumulated Deficit	Total
Balance at the beginning of period at Dec. 31, 2017	$ 3	$ 123,879	$ (169)	$ (41,561)	$ 82,152
Balance at the beginning of period (in shares) at Dec. 31, 2017	26,749,666
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, Stock offering, net of issuance costs		99,507			99,507
Issuance of common stock, Stock offering (in shares)	6,900,000
Issuance of common stock to nonemployees (in shares)	544,000
Stock-based compensation expense		1,966			1,966
Foreign currency translation			176		176
Net loss				(43,274)	(43,274)
Balance at the end of period at Dec. 31, 2018	$ 3	225,352	7	(84,835)	140,527
Balance at the end of period (in shares) at Dec. 31, 2018	34,193,666
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, Stock offering, net of issuance costs	$ 1	134,703			134,704
Issuance of common stock, Stock offering (in shares)	5,134,750
Issuance of common stock to nonemployees (in shares)	400,000
Stock-based compensation expense		4,657			4,657
Foreign currency translation			43		43
Net loss				(81,028)	(81,028)
Balance at the end of period at Dec. 31, 2019	$ 4	$ 364,712	$ 50	$ (165,863)	$ 198,903
Balance at the end of period (in shares) at Dec. 31, 2019	39,728,416

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (81,028,000)	$ (43,274,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	166,000	29,000
Stock-based compensation	4,657,000	1,966,000
Foreign currency transactions	43,000	97,000
Changes in assets and liabilities:
Other current assets	(1,158,000)	(2,821,000)
Other assets	(182,000)	(187,000)
Accounts payable	2,617,000	1,261,000
Accrued liabilities and other	1,388,000	1,700,000
NET CASH USED IN OPERATING ACTIVITIES	(73,497,000)	(41,229,000)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of property and equipment	(1,965,000)	(234,000)
NET CASH USED IN INVESTING ACTIVITIES	(1,965,000)	(234,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from issuance of common stock, net of issuance costs	134,704,000	99,765,000
Payment of offering costs for private placement		(1,002,000)
NET CASH PROVIDED BY FINANCING ACTIVITIES	134,704,000	98,763,000
Effect of exchange rates on cash, cash equivalents and restricted cash	23,000	56,000
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	59,265,000	57,356,000
Cash, cash equivalents and restricted cash at the beginning of period	147,871,000	90,515,000
Cash, cash equivalents and restricted cash at the end of period	207,136,000	$ 147,871,000
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Property and equipment purchases in accounts payable	49,000
Right-of-use assets obtained in exchange for lease obligations	$ 901,000

ORGANIZATION AND DESCRIPTION OF

ORGANIZATION AND DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2019
ORGANIZATION AND DESCRIPTION OF BUSINESS
ORGANIZATION AND DESCRIPTION OF BUSINESS	NOTE 1—ORGANIZATION AND DESCRIPTION OF BUSINESS Y‑mAbs Therapeutics, Inc. (“we,” “us,” “our,” the “Company,” or “Y‑mAbs”) is a late-stage clinical biopharmaceutical company focused on the development and commercialization of novel antibody-based therapeutic products for the treatment of cancer. The Company is headquartered in New York and was incorporated on April 30, 2015 under the laws of the State of Delaware.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	12 Months Ended
	Dec. 31, 2019
BASIS OF PRESENTATION
BASIS OF PRESENTATION	NOTE 2—BASIS OF PRESENTATION The Company has not generated any revenue and has incurred losses since inception. Operations of the Company are subject to certain risks and uncertainties, including, among others, uncertainty of drug candidate development; technological uncertainty; uncertainty regarding patents and proprietary rights; uncertainty in obtaining FDA approval in the United States and regulatory approval in other jurisdictions; marketing or sales capability or experience; uncertainty in getting adequate payer coverage and reimbursement; and dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Drug candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance‑reporting capabilities. The Company’s drug candidates are in the development stage. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. The Company’s financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. The Company has experienced positive financing cash flows due to public offering of 5,134,750 shares of our common stock in November 2019 and had an accumulated deficit of $165.9 million as of December 31, 2019 and $84.8 million as of December 31, 2018. Through December 31, 2019, the Company has funded its operations through proceeds from sales of shares of its common stock, including its initial public offering, or IPO, in September 2018, and secondary public offering in November 2019. As of December 31, 2019, the Company had cash and cash equivalents of $207.1 million, and as of December 31, 2018 the Company had cash and cash equivalents of $147.8 million. As of the issuance date of the annual financial statements for the year ended December 31, 2019, the Company expects that its cash and cash equivalents at December 31, 2019 will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next twelve months. The future viability of the Company, until such time that the Company has commercialized any of its products, is dependent on its ability to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies. The accompanying consolidated financial statements reflect the accounts of the Company and its wholly‑owned subsidiary and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). All intercompany balances and transactions have been eliminated.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 3—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual for research and development expenses, the accrual of milestone and royalty payments, the valuation of shares of common stock prior to becoming a public company and stock options. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid instruments with original maturities of three months or less from date of purchase to be cash equivalents. All cash and cash equivalents are held in highly rated securities including a Treasury money market fund which is unrestricted as to withdrawal or use. To date, the Company has not experienced any losses on its cash and cash equivalents. The carrying amount of cash and cash equivalents approximates its fair value due to its short-term and liquid nature. We maintain cash balances in excess of insured limits. We do not anticipate any losses with respect to such cash balances. Restricted cash represents a bank account with funds to cover the Company’s corporate credit card availability. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e. an exit price). The accounting guidance includes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy are as follows: • Level 1 — Unadjusted quoted prices for identical assets or liabilities in active markets; • Level 2 — Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability; and • Level 3 — Unobservable inputs for the asset or liability, which include management's own assumption about the assumptions market participants would use in pricing the asset or liability, including assumptions about risk. Cash equivalents held in money market funds are valued using other significant observable inputs, which represent a Level 2 measurement within the fair value hierarchy. The Company has no other cash equivalents and there were no money market funds held as of December 31, 2018. The following tables present the Company’s fair value hierarchy for its cash equivalents, which are measured at fair value on a recurring basis (in thousands): Fair Value Measurements at December 31, 2019 Using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 197,879 $ — $ 197,879 $ — $ 197,879 $ — $ 197,879 During the years ended December 31, 2019 and 2018, there were no transfers between Level 1, Level 2 and Level 3. Operating Leases As described below, the Company adopted Topic 842 as of January 1, 2019. The Company determines if an arrangement includes a lease at inception. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses its estimated incremental borrowing rate based on information available at the lease commencement date. Because most of the Company’s leases do not provide an implicit rate of return, an incremental borrowing rate is used based on the information available at the commencement date in determining the present value of lease payments on an individual lease basis. The Company’s incremental borrowing rate for a lease is the estimated rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company’s leases may include options to extend or terminate the lease which are included in the lease term when it is reasonably certain that it will exercise any such options. None of the Company’s leases contain any residual value guarantees. Lease expense is recognized on a straight-line basis over the expected lease term. Related variable lease costs incurred are not material to the Company. Topic 842 also provides practical expedients and certain exemptions for an entity’s ongoing accounting post implementation. The Company currently elected the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, we will not recognize right-of-use assets or liabilities, and this includes not recognizing right-of-use assets or liabilities for existing short-term leases of those assets in transition. We also elected the practical expedient to not separate lease and non-lease components for all of our leases. The Company has made an accounting policy election to account for each separate lease component of a contract and its associated non-lease components as a single lease component. See the Lease Agreements section in Note 6 for the related disclosures. Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight‑line method over the estimated useful life of each asset as follows: Estimated Useful Life Furniture and fixtures 5 years Machinery and equipment 5 years Leasehold improvements Shorter of life of lease or 15 years Depreciation and amortization expense on property and equipment was $166,000 and $29,000 for the years ended December 31, 2019 and 2018, respectively. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are charged to expense as incurred. Impairment of Long‑Lived Assets ASC 360, Property, Plant and Equipment, addresses the financial accounting and reporting for impairment or disposal of long‑lived assets. The Company reviews the recorded values of long‑lived assets for impairment whenever events or changes in business circumstance indicate that the carrying amount of an asset or group of assets may not be fully recoverable. Income Taxes The Company accounts for income taxes under the asset and liability approach for the financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to net operating loss carry forwards and temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. These assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which the temporary differences are expected to reverse. We maintain a full valuation allowance on our deferred tax assets based on cumulative historical and expected losses. If we commercialize our products and achieve profitability, we will consider the continued need for such valuation allowance. The Company prepares and files tax returns based on its interpretation of tax laws and regulations. In the normal course of business, the Company’s tax returns are subject to examination by various taxing authorities. Such examinations may result in future tax and interest assessments by these taxing authorities. In determining the Company’s tax provision for financial reporting purposes, the Company establishes a reserve for uncertain tax positions unless such positions are determined to be more likely than not of being sustained upon examination based on their technical merits. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes. Accordingly, the Company will report a liability for unrecognized tax benefits resulting from any uncertain tax positions taken or expected to be taken on a tax return. The Company’s policy is to recognize, when applicable, interest and penalties on uncertain tax positions as part of income tax expense. In accordance with guidance issued by Financial Accounting Standards Board (“FASB”), companies should make and disclose a policy election as to whether they will recognize deferred taxes for basis differences expected to reverse as Global Intangible Low‑Taxed Income (“GILTI”) or whether they will account for GILTI as period costs if and when incurred. The Company has elected to recognize the resulting tax with respect to the GILTI provision as a period cost. No costs were incurred by the Company through December 31, 2019 as a result of GILTI. Research and Development Costs Research and development costs are charged to operations when incurred and are included in operating expenses. Research and development costs consist principally of compensation cost for our employees and consultants that perform our research activities, the fees paid to maintain our licenses, the payments to third parties for manufacturing and clinical research organizations and additional product development, and consumables and other materials used in research and development. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Actual results could differ from the Company’s estimates. The Company is obligated to make certain milestone and royalty payments in accordance with the contractual terms of its license agreement with MSK based upon the resolution of certain contingencies. The Company records the milestone and royalty payment when the achievement of the milestone or payment of the milestone or royalty is probable and the amount of the payment is reasonably estimable. Research and development costs were $63.5 million and $34.3 million for the years ended December 31, 2019 and 2018, respectively. Patent Costs The Company expenses the costs of obtaining and maintaining patents as general and administrative expenses. Stock‑Based Compensation The Company measures stock options granted to employees and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards, over the requisite service period, which is the vesting period of the respective award. Forfeitures are accounted for as they occur. The Company issues stock options with only service‑based vesting conditions and records the expense for these awards using the straight‑line method over the requisite service period. Following the Company’s adoption of ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. The fair value of each stock option grant is estimated on the date of grant using the Black‑Scholes option pricing model. Prior to September 2018, the Company historically was a private company and lacks sufficient company‑specific historical and implied volatility information for its shares. Therefore, it estimates its expected share price volatility based on the historical volatility of a group of publicly‑traded peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded share price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards as the Company has limited historical data to support the expected term assumption. The expected term of stock options granted to non‑employees is equal to the contractual term of the option award. The risk‑free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends on common shares and does not expect to pay any cash dividends in the foreseeable future. Stock-based compensation costs were $4.7 million and $2.0 million for the years ended December 31, 2019 and 2018, respectively. Segment Information The Company is engaged solely in the discovery and development of novel antibody therapeutic products to treat cancer. Accordingly, the Company has determined that it operates in one operating segment. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with shareholders. The difference between net loss and comprehensive loss for the period presented in the accompanying financial statements was due to foreign currency translation. Foreign Currency The financial statements of our Danish subsidiary with a functional currency other than the U.S. dollar are translated into U.S. dollars using period‑end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates during the period for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss), net of tax, in stockholders’ equity. Foreign currency transaction gains and losses are included in the results of operations in other income and expense, and totaled $(43,000) and $(97,000) for the years ended December 31, 2019 and 2018, respectively. Recently Issued Accounting Pronouncements - Adopted In July 2018, the FASB issued Accounting Standards Update No. 2018-09 (“ASU 2018-09”), Codification Improvements, which clarify, correct errors in, or make minor improvements to a variety of ASC topics. The changes in ASU 2018-09 are not expected to have a significant effect on current accounting practices. Some of the amendments in this update do not require transition guidance and will be effective upon this update. However, many of the updates do have transition guidance with effective dates for periods beginning after December 15, 2018. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In June 2018, the FASB issued ASU No. 2018‑07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share‑Based Payment Accounting (“ASU 2018‑07”). ASU 2018‑07 is intended to simplify aspects of share‑based compensation issued to non‑employees by making the guidance consistent with the accounting for employee share‑based compensation. ASU 2018‑07 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In February 2018, the FASB issued Accounting Standards Update No. 2018‑02, (“ASU 2018-02”), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018‑02 allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018‑07 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued Accounting Standards Update No. 2016‑02 (“ASU 2016‑02”), Leases, which is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018 with early adoption permitted. Under ASU 2016‑02, lessees will be required to recognize for most leases, at the commencement date of the lease, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease measured on a discounted basis, and a right‑to‑use asset, which is an asset that represents the lessee’s right to use or control the use of a specified asset for the lease term. Topic 842 was subsequently amended by ASU 2017-13, Revenue and Leases: Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments; ASU 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; ASU No. 2018-11, Targeted Improvements and ASU No. 2018-20, Narrow Scope Improvements for Lessors. The Company adopted the new leasing standards using the modified retrospective transition approach as of January 1, 2019, with no restatement of prior periods or cumulative adjustment to retained earnings. An entity may choose to use either (1) its effective date or (2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company used the effective date as our date of initial application. Consequently, financial information was not updated and the disclosures required under the new standard are not provided for dates and periods before January 1, 2019. The new standard also provides a number of optional practical expedients in transition. The Company elected the package of practical expedients, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. Upon adoption of the new leasing standards, the Company recognized a lease liability of $1.8 million and a related right-of-use asset of $1.5 million with the difference being due to the elimination of previously reported deferred rent. The Company subsequently entered into two new lease agreements during the three months ended March 31, 2019, and recognized an incremental lease liability and related right-of-use asset of $0.9 million. Please refer to lease footnotes at Note 6 License Agreement And Commitments. Recently Issued Accounting Pronouncements – Not Yet Adopted In August 2018, the FASB issued Accounting Standards Update No. 2018-15 (“ASU 2018-15”), Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 clarifies certain aspects of ASU 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, which was issued in April 2015. Specifically, ASU 2018-14 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal use software (and hosting arrangements that include an internal-use software license). ASU 2018-15 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years with early adoption permitted. The Company is currently evaluating the impact its adoption may have on its consolidated financial statements .

NET LOSS PER SHARE

NET LOSS PER SHARE	12 Months Ended
	Dec. 31, 2019
NET LOSS PER SHARE
NET LOSS PER SHARE	NOTE 4—NET LOSS PER SHARE Basic net loss per share (“EPS”) is calculated by dividing net loss attributable to common stockholders by the weighted average common stock outstanding. Diluted EPS is calculated by adjusting weighted average common shares outstanding for the dilutive effect of common stock options and restricted stock units. In periods in which a net loss is recorded, no effect is given to potentially dilutive securities, since the effect would be antidilutive. Securities that could potentially dilute basic EPS in the future were not included in the computation of diluted EPS because to do so would have been antidilutive. The calculations of basic and diluted net loss per share are as follows: For the year ended December 31, 2019 2018 (in thousands, except share and per share amounts) Net loss (numerator) $ (81,028) $ (43,274) Weighted-average shares (denominator) 35,183,488 28,772,384 Basic and diluted net loss per share $ (2.30) $ (1.50) Potentially dilutive securities outstanding as of December 31, 2019 and 2018 relate to stock options outstanding of 4,005,873 and 3,357,873 shares, respectively.

ACCRUED LIABILITIES

ACCRUED LIABILITIES	12 Months Ended
	Dec. 31, 2019
ACCRUED LIABILITIES
ACCRUED LIABILITIES	NOTE 5—ACCRUED LIABILITIES Accrued short‑term liabilities are as follows: December 31, December 31, 2019 2018 (in thousands) Accrued milestone and royalty payments $ 354 $ 1,475 Accrued clinical costs 1,584 63 Accrued compensation and board fees 1,475 1,144 Accrued rent — 44 Accrued manufacturing costs 760 — Other 377 525 Total $ 4,550 $ 3,251

LICENSE AGREEMENTS AND COMMITME

LICENSE AGREEMENTS AND COMMITMENTS	12 Months Ended
	Dec. 31, 2019
LICENSE AGREEMENTS AND COMMITMENTS
LICENSE AGREEMENTS AND COMMITMENTS	NOTE 6—LICENSE AGREEMENTS AND COMMITMENTS The Company has entered into two license agreements and certain other agreements with MSK. The license agreements are further described below as the MSK License and the CD33 License Agreement. Additionally, through a Settlement and Assumption and Assignment of the MSK License and Y-mAbs Sublicense Agreement ( “SAAA”) with MabVax and MSK, the Company has established a direct license with MSK relating to the GD2-GD3 Vaccine, which was originally sublicensed in 2018 from MabVax. These license agreements with MSK grant the Company certain patent rights and intellectual property rights, and in consideration thereof, the Company agreed to make certain payments and issue shares of the Company’s common stock to MSK. Certain of the payments are contingent milestone and royalty payments, the terms of which are further described below. Amounts disclosed in footnote 5 for accrued milestone and royalty payments are inclusive of obligations under the MSK License and CD33 License Agreement, collectively. MSK License Agreement On August 20, 2015, we entered into the MSK License Agreement that grants us a worldwide, sublicensable license to MSK’s rights to certain patent rights and intellectual property rights to develop, make, and commercialize licensed products and to perform services for all therapeutic and diagnostic uses in the field of cancer diagnostics and cancer treatments. The patents and patent applications covered by this agreement are directed, in part, to naxitamab, an anti-GD2 antibody, and omburtamab, which is an anti B3‑H7 antibody, as well as affinity matured versions of certain antibodies and certain single chain variable fragments (Fv) constructs, and their use for immunotherapy, targeting the treatment of oncology indications. Upon entering into the MSK License Agreement in 2015 and in exchange for the licenses, we paid MSK an upfront payment, issued 1,428,500 shares of our common stock to MSK and provided certain anti‑dilution rights to MSK. In addition, we are required to pay to MSK certain royalty and milestone payments. We expensed the upfront payment and the issuance of shares to MSK in 2015. We also recorded expense related to common stock issued related to certain anti‑dilution rights held by MSK. The MSK License Agreement requires us to pay to MSK mid to high single digit royalties based on annual net sales of licensed products or the performance of licensed services by us and our affiliates and sublicensees. We are obligated to pay annual minimum royalties of $80,000 over the royalty term, commencing on the fifth anniversary of the license agreement. These amounts are non‑refundable but are creditable against royalty payments otherwise due under the MSK License Agreement. The Company expensed the total minimum royalty payments of $1,200,000 in 2016. As of December 31, 2019, $29,000 was recorded as short-term accrued liabilities and $1,171,000 was recorded as long‑term accrued liabilities. As of December 31, 2018, the $1,200,000 was recorded as long‑term accrued liabilities. We are also obligated to pay MSK certain clinical, regulatory and sales‑based milestone payments under the MSK License Agreement. Certain of the clinical and regulatory milestone payments become due at the earlier of completion of the related milestone activity or the date indicated in the MSK License Agreement. Total clinical and regulatory milestones potentially due under the MSK License Agreement are $2,450,000 and $9,000,000, respectively. There are also sales‑based milestones, totaling $20,000,000, that become due should the Company achieve certain amounts of sales of licensed products. The Company records milestones in the period in which the contingent liability is probable and the amount is reasonably estimable. In addition, to the extent we enter into sublicense arrangements, we are obligated to pay to MSK a percentage of certain payments received from sublicensees of the rights licensed to us by MSK, which percentage will be based upon the achievement of certain clinical milestones. The Company has not entered into any sublicenses related to the MSK License Agreement. Failure by the Company to meet certain conditions under the arrangement could cause the related license to such licensed product to be canceled and could result in termination of the entire arrangement with MSK. In addition, the Company may terminate the MSK License Agreement with prior written notice to MSK. Milestones of $75,000 were expensed in the twelve months ended December 31, 2019. The Company expensed none during the twelve months ended December 31, 2018. We paid $725,000 under this arrangement in 2019. As of December 31, 2019, $225,000 of accrued milestone obligations were recorded in accrued short‑term liabilities and $300,000 was recorded within accrued long‑term liabilities. As of December 31, 2018, $875,000 of accrued milestone obligations were recorded in accrued short term liabilities and $300,000 was recorded within accrued long term liabilities. These clinical milestone-related charges were recorded as research and development expense upon determination that payment was probable after satisfying the financing requirements described herein. Research and development is inherently uncertain and as described above, should such research and development fail, the MSK License Agreement is cancelable at the Company’s option. The Company also considered the development risk and each party’s termination rights under the agreement when considering whether any regulatory‑based milestone payments, certain of which also contain time‑based payment requirements, were probable. Such regulatory‑based obligations were determined not to be probable as of December 31, 2019 and 2018, and therefore have not been accrued. CD33 License Agreement On November 13, 2017, we entered into an exclusive license agreement for MSK rights in connection with certain CD33 antibodies, which we refer to as the CD33 License Agreement. The CD33 License Agreement obligates us to pay to MSK mid to high single digit royalties based on annual net sales of licensed products or the performance of licensed services by us and our affiliates and sublicensees. We are obligated to pay annual minimum royalties of $40,000 over the royalty term, increasing to $60,000 once a patent within the licensed rights is issued, and commencing on the tenth anniversary of the CD33 License Agreement. These amounts are non‑refundable but are creditable against royalty payments otherwise due under the agreement. We were also obligated to pay MSK certain fees under a sponsored research agreement under the CD33 License Agreement during the years 2017 through 2019. In addition, milestone payments become due upon achievement of the related clinical, regulatory or sales‑based milestones defined in the CD33 License Agreement. Certain of these payments become due at the earlier of completion of the related milestone activity or the date indicated in the CD33 License Agreement. Total potential clinical and regulatory milestones potentially due under the CD33 License Agreement are $1,050,000. There are also sales‑based milestones that become due should the Company achieve certain amounts of sales of licensed products, with total sales‑based milestones potentially due of $7,500,000. The Company may terminate the CD33 License Agreement with prior written notice to MSK. The Company records milestones in the period in which the contingent liability is probable and the amount is reasonably estimable. In addition, to the extent we enter into sublicense arrangements, we are obligated to pay to MSK a percentage of certain payments received from sublicensees of the rights licensed to us by MSK, which percentage will be based upon the achievement of certain clinical milestones. The Company has not entered into any sublicenses related to the CD33 License Agreement. In 2017, the total milestone obligations expensed under the CD33 License Agreement with MSK was $550,000, all of which related to clinical milestones. Such clinical milestone obligations become due either based upon the passage of time or achievement of the related milestone activities. None of these clinical milestone obligations were paid in 2018 or 2019. A total of $450,000 was recorded as accrued long‑term liabilities and $100,000 as accrued short-term liabilities as of December 31, 2019, and the total amount $550,000 was recorded as accrued long-term liabilities as of December 31, 2018. Research and development is inherently uncertain and as described above, should such research and development fail, the CD33 License Agreement is cancelable at the Company’s option. The Company considered risks as well as each party’s termination rights under the CD33 License Agreement when considering whether any regulatory‑based milestone payments and minimum royalty payments, certain of which also contain time‑based payment requirements, were probable. Given the uncertainty associated with research and development and the Company’s ability to cancel the CD33 License Agreement, such obligations were determined not to be probable as of December 31, 2019 and December 31, 2018 and therefore have not been accrued. MabVax Sublicense Agreement On June 27, 2018, we entered into a sublicense agreement with MabVax pursuant to which MabVax has sublicensed to the Company certain of MabVax’s patent rights and know‑how for development and commercialization of products for the prevention or treatment of neuroblastoma by means of administering a GD2-GD3 Vaccine, granted to MabVax pursuant to an exclusive license agreement between MabVax and MSK. Under the sublicense agreement, the Company has paid license fee of $1,300,000 to MabVax. The initial license fee of $700,000 was expensed and paid in 2018 and the continuation fee of $600,000 was accrued in 2018, and paid in 2019. The Company has agreed to become solely responsible for future amounts payable to MSK and to handle other of MabVax’ obligations applicable to the licensed indication towards MSK. This includes the obligation to pay development milestones totaling $1,400,000 and mid single digit royalty payments to MSK. On March 21, 2019, MabVax filed a voluntary petition for relief under Chapter 11 of the Bankruptcy Code. On December 2, 2019, we entered into the SAAA to preserve the License Agreement and the rights granted to us under the Sublicense Agreement and to create a direct relationship between MSK and us with respect to the rights covered under the Sublicense Agreement. Research and development is inherently uncertain and as described above, should such research and development fail, the SAAA is cancelable at the Company’s option. The Company considered risks as well as each party’s termination rights under the SAAA when considering whether any milestone payments and minimum royalty payments were probable. Given the uncertainty associated with research and development and the Company’s ability to cancel the SAAA, such obligations were determined not to be probable as of December 31, 2019 and therefore have not been accrued. Other agreements We have also entered into various other support agreements with MSK including a sponsored research agreement to provide research services related to the intellectual property licensed under the MSK License Agreement; a master data services agreement, for services provided by approximately five full time employees at MSK, who are engaged in transferring clinical data, databases, regulatory files and other know‑how included in the MSK License Agreement to the Company; a master clinical trial agreement pursuant to which we committed to fund certain clinical trials at MSK; two separate core facility service agreements pursuant to which we committed to obtaining certain laboratory services from MSK; and a CD33 sponsored research agreement pursuant to which we agreed to pay MSK to provide research services over a period of two years related to the intellectual property licensed under the CD33 License Agreement. During 2019 and 2018, we incurred research and development expenses of $6.8 million and $5.8 million, respectively, under these agreements. Lease Agreements In February 2019, the Company entered into a lease agreement in connection with its 4,500 square feet laboratory in New Jersey. The term of the lease is three years from the date the Company occupied the premises, with an option to extend for an additional two years which the Company expects to exercise and has included in the determination of the related lease liability. Fixed rent payable under the lease is approximately $144,000 per annum and is payable in equal monthly installments of approximately $12,000. January 2018, the Company entered into a lease agreement in connection with its corporate headquarters in New York. The term of the lease is five years from the date the Company begins to occupy the premises. Fixed rent payable under the lease is approximately $384,000 per annum and is payable in equal monthly installments of approximately $32,000, which are recognized on a straight‑line basis. Additionally, the Company entered a three‑year lease agreement for the lease of certain office space in Denmark in February 2018, as amended in November 2018 and February 2019. The lease is payable in monthly installments of approximately $19,000, which are recognized on a straight‑line basis. Until the end of March 2018, the Company, has maintained a lease for certain office space in Denmark as further described in footnote 9, Related Party Transactions. As described above in Note 3, the Company adopted Topic 842 as of January 1, 2019. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under Topic 840. Total operating lease costs were $676,000 and $394,000 for the year ended December 31, 2019 and 2018, respectively. During the year ended December 31, 2019, the expenses were recorded as $493,000 in research and development expense and $183,000 in general and administrative expense. During year ended December 31, 2018, the expenses $394,000 were all recorded in general and administrative expense. Cash paid for amounts included in the measurement of lease liabilities for year ended December 31, 2019 was $606,000, and was included in net cash used in operating activities in the Company’s Consolidated Statements of Cash Flows. Maturities of operating lease liabilities at December 31, 2019 were as follows (in thousands): Operating Leases at December 31, 2019 2020 $ 749 2021 753 2022 646 2023 539 Thereafter 77 Total lease payments 2,764 Less: Imputed interest (534) Total operating lease liabilities at December 31, 2019 $ 2,230 Disclosures related to periods prior to the adoption of Topic 842: Future minimum lease payments, including imputed interest, under non-cancelable operating leases at December 31, 2018 were as follows (in thousands): Contractual Obligations at December 31, 2018 2019 $ 510 2020 616 2021 616 2022 616 2023 462 Thereafter 64 Total lease payments 2,884 Less: Imputed interest — Contractual obligations at December 31, 2018 $ 2,884 Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company uses its estimate of its incremental borrowing rate based on the information available at the lease commencement date. As of December 31, 2019, the weighted average remaining lease term is 3.83 years and the weighted average discount rate used to determine the operating lease liability was 11.0%.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2019
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	NOTE 7—STOCKHOLDERS’ EQUITY Authorized Stock As of December 31, 2019 and 2018, the Company has authorized a total of 105,500,000 shares, 100,000,000 of which are to be common stock, par value $0.0001 per stock, and 5,500,000 of which are to preferred stock, par value $0.0001 per share. Common Stock Each share of common stock is entitled to one vote. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any, subject to preferential dividend rights of the preferred stock, none of which have been issued. The Company has issued 39,728,416 shares of its common stock as of December 31, 2019 and 34,193,666 shares of its common stock as of December 31, 2018. Preferred Stock Preferred stock may be issued from time to time in one or more series with such designations, preferences and relative participating, optional or other special rights and qualifications, limitations or restrictions as approved by the Company’s Board of Directors. No preferred stock has been issued as of December 31, 2019 or December 31, 2018. Stock grant agreements with non‑employees In August 2015, we entered into certain stock grant agreements with non‑employees of the Company. We agreed to issue a total of 2,800,000 shares of common stock to two non‑employee physicians who were involved in the development of technology licensed from MSK in consideration for their prior service. These two physicians were employees of MSK on the date of grant. The shares are released according to a vesting schedule. A total of 560,000 shares were issued in 2015, and a total of 448,000 shares issued in each of 2016 and 2017. In 2018 a total of 544,000 shares were issued to the two researchers, whereby one of the two grants were fully issued. In 2019 a total of 400,000 shares were issued to one of the physicians, and the remaining 400,000 shares are to be issued in 2020, subject to certain conditions, such that the total grant will have been issued. The total award was expensed at its estimated fair value in 2015, as no future service was required to continue to vest in and receive the shares. In April 2018, the Company granted 72,373 common stock options to a non‑employee physician employed by MSK under our 2015 Equity Incentive Plan (the 2015 Plan). The options become exercisable over a four‑year period, with the first twenty‑five percent (25%) exercisable twelve months from the date of grant and the remainder becoming exercisable ratably each month over the three years thereafter. The contractual term of the option award is 10 years from the date of grant. The total award was expensed at its estimated fair value in April 2018, as no future service was required by the non‑employee to continue to vest in the option grant. The shares will become immediately exercisable upon the occurrence of a change in control, as defined in the 2015 Plan as further described in footnote 8, Stock Options. Issuance of common stock In November 2019, we completed a secondary public offering and issued 5,134,750 shares of Common Stock at a purchase price of $28.00 per share for an aggregate consideration of $134,704,000, net of issuance costs of $9,100,000. In September 2018, we completed an initial public offering and issued 6,900,000 shares of Common Stock at a purchase price of $16.00 per share for an aggregate consideration of $99,507,000, net of issuance costs of $10,900,000.

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2019
SHARE-BASED COMPENSATION
SHARE-BASED COMPENSATION	NOTE 8—SHARE-BASED COMPENSATION 2015 Equity Incentive Plan Our board of directors and stockholders have approved and adopted the 2015 Plan, which provided for the grant of incentive stock options, within the meaning of Section 422 of the Code (the Internal Revenue Code), to our employees and any parent and subsidiary corporations’ employees, and for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock and restricted stock units to our employees, directors and consultants and our parent and subsidiary corporations’ employees and consultants. A total of 4,500,000 shares of our common stock were reserved for issuance pursuant to the 2015 Plan. Options granted under the 2015 Plan vest according to the schedule specified in the grant agreements, which is generally a four year period and generally become immediately exercisable upon the occurrence of a change in control, as defined. Upon the 2018 Equity Incentive Plan (the “2018 Plan’) becoming effective in September 2018, no further grants are allowed under the 2015 Plan. 2018 Equity Incentive Plan Our board of directors and stockholders approved and adopted the 2018 Plan, which became effective upon the Company’s initial public offering in September 2018 and which provides for the grant of incentive stock options, within the meaning of Section 422 of the Code (the Internal Revenue Code), to our employees and any parent and subsidiary corporations’ employees, and for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock and restricted stock units to our employees, directors and consultants and our parent and subsidiary corporations’ employees and consultants. A total of 5,500,000 shares of our common stock, inclusive of the awards previously granted under the 2015 Equity Incentive Plan, are reserved for issuance pursuant to the 2018 Plan. In addition, the number of shares available for issuance under the 2018 Plan will also include an annual increase on the first day of each fiscal year beginning in 2019, equal to 4% of the outstanding shares of common stock as of the last day of our immediately preceding fiscal year. The exercise price of options granted under the plans must at least be equal to the fair market value of our common stock on the date of grant. The term of an incentive stock option may not exceed 10 years, except that with respect to any participant who owns more than 10% of the voting power of all classes of our outstanding stock, the term must not exceed five years and the exercise price must equal at least 110% of the fair market value on the grant date. The administrator will determine the methods of payment of the exercise price of an option, which may include cash, shares or other property acceptable to the administrator, as well as other types of consideration permitted by applicable law. Options granted under the 2018 Plan vest according to the schedule specified in the grant agreements, which is generally over a four year period and generally become immediately exercisable upon the occurrence of a change in control, as defined. Stock Option Valuation and Restricted Stock Units During the years ended December 31, 2019 and 2018, stock‑based compensation expenses for stock option grants were $4,581,000 and $1,381,000, respectively, for options granted to employees. During 2019 the expenses were recorded as $933,000 in research and development expense and $3,647,000 in general and administrative expense. During 2018 the expenses were recorded as $276,000 in research and development expense and $1,105,000 in general and administrative expense. Other than $4,581,000 stock option compensation in 2019, another $76,000 restricted stock units, $69,000 in research and development expense and $7,000 in general and administrative expense were recorded in 2019. The total stock based compensation was $4,657,000 in 2019 and $1,381,000 in 2018, respectively. The assumptions that the Company used to determine the fair value of the stock options granted to employees and directors were as follows, presented on a weighted average basis: Year Ended Year Ended December 31, 2019 December 31, 2018 Risk-free interest rate 1.78 % 2.89 % Expected term (in years) 6.3 6.3 Expected volatility 60.6 % 57.8 % Expected dividend yield — % — % The assumptions that the Company used to determine the fair value of the stock options granted to non‑employees in 2018 were as follows, presented on a weighted average basis: Year Ended December 31, 2018 Risk-free interest rate 3.00 % Expected term (in years) 10.0 Expected volatility 62.7 % Expected dividend yield — % There were no stock options granted to non-employees in 2019. The Company recognizes compensation expense for only the portion of awards that vest. The following table summarizes common stock options issued and outstanding: Weighted Weighted Aggregate average average intrinsic remaining exercise value contractual Options price (in thousands) life (years) Outstanding and expected to vest at December 31, 2018 3,357,873 $ 7.74 $ 43,224 7.90 Granted 648,000 $ 25.88 Outstanding and expected to vest at December 31, 2019 4,005,873 $ 10.67 $ 82,944 7.34 Exercisable at December 31, 2019 2,495,433 $ 5.31 $ 64,738 6.41 The weighted average grant‑date fair value of stock options granted during the years ended December 31, 2019 and 2018 was $14.92 and $9.58 per share, respectively. The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. As of December 31, 2019 and 2018, we had $15,942,000 and $10,848,000, respectively, of unrecognized compensation related to employee stock options that are expected to vest over a period of 2.72 years in 2019 and 2.82 years in 2018. Restricted Stock Unit Activity During the year ended December 31, 2019, stock-based compensation for restricted stock unit grants was $76,000. Of this expense $76,000, $69,000 were recorded in research and development expense and $7,000 in general and administrative expense. There was no stock based compensation for restricted stock units during the year ended December 31, 2018. The following table summarizes restricted stock units issued and outstanding: Restricted Stock Units Outstanding and expected to vest at December 31, 2018 — Granted 10,296 Outstanding and expected to vest at December 31, 2019 10,296 The weighted average fair value of restricted stock units granted during the year ended December 31, 2019 was $23.11. As of December 31, 2019, we had $163,000 of unrecognized compensation related to employee restricted stock units that are expected to vest over a period of 2.05 years.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2019
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	NOTE 9—RELATED PARTY TRANSACTIONS MSK is a shareholder of the Company and under the MSK License Agreement, the CD33 License Agreement, CTA, CFAs, SRA and MDSA, we have expensed costs in the total amount of $6,832,000 and $5,761,000 in the years ended December 31, 2019 and 2018, respectively, for milestones, minimum royalties, research and development costs and patent activities. Please refer to footnote 6 for additional details on our various agreements with MSK. As of December 31, 2019 and 2018, we had a total of $4,171,000 and $4,475,000, respectively, recorded as accounts payable and accrued liabilities related to amounts due to MSK. In July 2016, the Company entered into an agreement of lease with a shareholder of the Company, Weco Group, in connection with the Company’s subsidiary in Denmark. The lease payable thereunder was approximately $4,000 per month and, as the lease could be terminated with three months’ notice, any future rent commitment thereunder will amount to approximately $12,000. The lease terminated in March 2018, when the Company moved to a new third‑party lease. In addition, the Company has reimbursed Weco Group for certain administrative expenses. No expenses were reimbursed during 2019, and for 2018, the total expenses, including rent, equaled $44,000.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
INCOME TAXES	NOTE 10—INCOME TAXES Domestic and foreign loss before income taxes are as follows: For The For The Year Ended Year Ended December 31, December 31, 2019 2018 (thousands) (thousands) United States $ (80,598) $ (42,456) Foreign (430) (818) Total $ (81,028) $ (43,274) The Company provided no current and deferred income tax benefits on net losses of $(81,028,000) and $(43,274,000) for years ended December 31, 2019 and 2018, respectively, and maintains a full valuation allowance against its net deferred tax assets. The difference between income taxes expected at the U.S. federal statutory income tax rate of 21% for tax years ended December 31, 2019 and December 31, 2018, respectively, and income taxes provided are set forth below : December 31, 2019 December 31, 2018 (thousands) (thousands) Taxes on income at U.S. federal statutory rate $ (17,016) $ (9,127) State and local taxes, net of federal tax effects (11,022) (5,778) Effect of rate change (22) (9) Foreign tax rate differential (4) (8) Valuation allowance 33,984 16,376 Tax credits (5,924) (1,431) Other 4 (23) Total — — Significant components of the Company’s net deferred tax assets/(liabilities) are as follows: December 31, 2019 December 31, 2018 (thousands) (thousands) Deferred tax assets/(liabilities): Acquired intangibles $ 2,504 $ 2,682 Accrued bonus 153 — Unrealized foreign exchange loss (261) (163) Accrued royalty 415 415 Stock based compensation 2,594 981 Net operating loss carryforwards 51,649 25,285 Tax credit carryforwards 8,412 2,789 ROU asset (625) — Lease liability 711 — Other (63) 78 Total deferred tax assets/(liabilities) 65,489 32,067 Valuation allowance (65,489) (32,067) Net deferred tax assets/(liabilities) — — The Company recognizes income tax benefits for tax positions determined more likely than not to be sustained upon examination, based on the technical merits of the positions. As of December 31, 2019, and 2018, the Company has determined that there were no uncertain tax positions. The Company’s tax returns for the years 2018, 2017 and 2016 are open for tax examination by U.S. federal and state, and the Danish tax authorities. The Company maintains a full valuation allowance on its U.S. and foreign deferred tax assets. The assessment regarding whether a valuation allowance is required considers both positive and negative evidence when determining whether it is more‑likely‑than‑not that deferred tax assets are recoverable. In making this assessment, significant weight is given to evidence that can be objectively verified. In its evaluation, the Company considered its cumulative losses historically and in recent years and its forecasted losses in the near‑term as significant negative evidence. Based upon review of available positive and negative evidence, the Company determined that the negative evidence outweighed the positive evidence and a full valuation allowance on its U.S. and foreign deferred tax assets will be maintained. The Company will continue to assess the realizability of its deferred tax assets and will adjust the valuation allowance as needed. As of December 31, 2019, the Company had U.S. federal and state net operating loss (“NOL”) carryforwards of approximately $147,839,000 and $148,608,000, respectively, which are available to reduce future taxable income. The Company also had approximately $148,608,000 of unused NOL carryforwards for New York City purposes. The Company also had U.S. federal tax credits of $8,412,000 as of December 31, 2019, which may be used to offset future tax liabilities. The federal NOL carryforwards of approximately $29,909,000 will expire through 2037. The federal NOL of approximately $117,930,000 can be carried forward indefinitely but limited to offset 80% of taxable income. The New York State and New York City NOL and tax credit carryforwards will begin to expire in 2035. The NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986 (“IRC”). The Company has performed an analysis of its Section 382 ownership changes through December 31, 2018. Due to the large annual limitation, the Company believes that it is more likely than not that none of the net operating loss carryforwards will expire as a result of the limitation from the ownership change under Section 382. The Company also has Danish NOL carryforwards of $1,540,000, which have an indefinite carryforward period.

OTHER BENEFITS

OTHER BENEFITS	12 Months Ended
	Dec. 31, 2019
OTHER BENEFITS
OTHER BENEFITS	NOTE 11—OTHER BENEFITS The Company has established a retirement program for employees of our Danish subsidiary pursuant to which all such employees can contribute an amount at their election from their base compensation and may receive contributions from our Danish subsidiary. Contributions from our Danish subsidiary were immaterial during the years ended December 31, 2019 and 2018. In addition, health insurance benefits for our Danish employees are fully paid for by such employees. Our Danish subsidiary does not incur any costs for these health insurance benefits. On October 1, 2018, the Company adopted a defined contribution 401(k) savings plan (the 401(k) plan) covering all U.S. employees of the Company. Participants may elect to defer a percentage of their pretax or after-tax compensation to the 401(k) plan, subject to defined limitations. The plan allows for a discretionary match by the Company. The Company made no matching contributions to the plan during the years ended December 31, 2019 and December 31, 2018.

QUARTERLY CONSOLIDATED FINANCIA

QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited)	12 Months Ended
	Dec. 31, 2019
QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited)
QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited)	NOTE 12—QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited) (In thousands, except per share amounts) 2019 March 31 June 30 September 30 December 31 Loss from operations $ (16,253) $ (18,634) $ (24,359) $ (23,758) Net loss (15,934) (18,036) (23,922) (23,136) Net loss per share - basic and diluted $ (0.47) $ (0.53) $ (0.70) $ (0.60) 2018 March 31 June 30 September 30 December 31 Loss from operations $ (7,479) $ (10,258) $ (11,415) $ (14,078) Net loss (7,483) (10,305) (11,426) (14,060) Net loss per share - basic and diluted $ (0.28) $ (0.38) $ (0.42) $ (0.42)

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual for research and development expenses, the accrual of milestone and royalty payments, the valuation of shares of common stock prior to becoming a public company and stock options. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid instruments with original maturities of three months or less from date of purchase to be cash equivalents. All cash and cash equivalents are held in highly rated securities including a Treasury money market fund which is unrestricted as to withdrawal or use. To date, the Company has not experienced any losses on its cash and cash equivalents. The carrying amount of cash and cash equivalents approximates its fair value due to its short-term and liquid nature. We maintain cash balances in excess of insured limits. We do not anticipate any losses with respect to such cash balances. Restricted cash represents a bank account with funds to cover the Company’s corporate credit card availability.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e. an exit price). The accounting guidance includes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy are as follows: • Level 1 — Unadjusted quoted prices for identical assets or liabilities in active markets; • Level 2 — Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability; and • Level 3 — Unobservable inputs for the asset or liability, which include management's own assumption about the assumptions market participants would use in pricing the asset or liability, including assumptions about risk. Cash equivalents held in money market funds are valued using other significant observable inputs, which represent a Level 2 measurement within the fair value hierarchy. The Company has no other cash equivalents and there were no money market funds held as of December 31, 2018. The following tables present the Company’s fair value hierarchy for its cash equivalents, which are measured at fair value on a recurring basis (in thousands): Fair Value Measurements at December 31, 2019 Using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 197,879 $ — $ 197,879 $ — $ 197,879 $ — $ 197,879 During the years ended December 31, 2019 and 2018, there were no transfers between Level 1, Level 2 and Level 3.
Operating Leases	Operating Leases As described below, the Company adopted Topic 842 as of January 1, 2019. The Company determines if an arrangement includes a lease at inception. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses its estimated incremental borrowing rate based on information available at the lease commencement date. Because most of the Company’s leases do not provide an implicit rate of return, an incremental borrowing rate is used based on the information available at the commencement date in determining the present value of lease payments on an individual lease basis. The Company’s incremental borrowing rate for a lease is the estimated rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company’s leases may include options to extend or terminate the lease which are included in the lease term when it is reasonably certain that it will exercise any such options. None of the Company’s leases contain any residual value guarantees. Lease expense is recognized on a straight-line basis over the expected lease term. Related variable lease costs incurred are not material to the Company. Topic 842 also provides practical expedients and certain exemptions for an entity’s ongoing accounting post implementation. The Company currently elected the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, we will not recognize right-of-use assets or liabilities, and this includes not recognizing right-of-use assets or liabilities for existing short-term leases of those assets in transition. We also elected the practical expedient to not separate lease and non-lease components for all of our leases. The Company has made an accounting policy election to account for each separate lease component of a contract and its associated non-lease components as a single lease component. See the Lease Agreements section in Note 6 for the related disclosures.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight‑line method over the estimated useful life of each asset as follows: Estimated Useful Life Furniture and fixtures 5 years Machinery and equipment 5 years Leasehold improvements Shorter of life of lease or 15 years Depreciation and amortization expense on property and equipment was $166,000 and $29,000 for the years ended December 31, 2019 and 2018, respectively. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are charged to expense as incurred.
Impairment of Long-Lived Assets	Impairment of Long‑Lived Assets ASC 360, Property, Plant and Equipment, addresses the financial accounting and reporting for impairment or disposal of long‑lived assets. The Company reviews the recorded values of long‑lived assets for impairment whenever events or changes in business circumstance indicate that the carrying amount of an asset or group of assets may not be fully recoverable.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability approach for the financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to net operating loss carry forwards and temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. These assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which the temporary differences are expected to reverse. We maintain a full valuation allowance on our deferred tax assets based on cumulative historical and expected losses. If we commercialize our products and achieve profitability, we will consider the continued need for such valuation allowance. The Company prepares and files tax returns based on its interpretation of tax laws and regulations. In the normal course of business, the Company’s tax returns are subject to examination by various taxing authorities. Such examinations may result in future tax and interest assessments by these taxing authorities. In determining the Company’s tax provision for financial reporting purposes, the Company establishes a reserve for uncertain tax positions unless such positions are determined to be more likely than not of being sustained upon examination based on their technical merits. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes. Accordingly, the Company will report a liability for unrecognized tax benefits resulting from any uncertain tax positions taken or expected to be taken on a tax return. The Company’s policy is to recognize, when applicable, interest and penalties on uncertain tax positions as part of income tax expense. In accordance with guidance issued by Financial Accounting Standards Board (“FASB”), companies should make and disclose a policy election as to whether they will recognize deferred taxes for basis differences expected to reverse as Global Intangible Low‑Taxed Income (“GILTI”) or whether they will account for GILTI as period costs if and when incurred. The Company has elected to recognize the resulting tax with respect to the GILTI provision as a period cost. No costs were incurred by the Company through December 31, 2019 as a result of GILTI.
Research and Development Costs	Research and Development Costs Research and development costs are charged to operations when incurred and are included in operating expenses. Research and development costs consist principally of compensation cost for our employees and consultants that perform our research activities, the fees paid to maintain our licenses, the payments to third parties for manufacturing and clinical research organizations and additional product development, and consumables and other materials used in research and development. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Actual results could differ from the Company’s estimates. The Company is obligated to make certain milestone and royalty payments in accordance with the contractual terms of its license agreement with MSK based upon the resolution of certain contingencies. The Company records the milestone and royalty payment when the achievement of the milestone or payment of the milestone or royalty is probable and the amount of the payment is reasonably estimable. Research and development costs were $63.5 million and $34.3 million for the years ended December 31, 2019 and 2018, respectively.
Patent Costs	Patent Costs The Company expenses the costs of obtaining and maintaining patents as general and administrative expenses.
Stock-Based Compensation	Stock‑Based Compensation The Company measures stock options granted to employees and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards, over the requisite service period, which is the vesting period of the respective award. Forfeitures are accounted for as they occur. The Company issues stock options with only service‑based vesting conditions and records the expense for these awards using the straight‑line method over the requisite service period. Following the Company’s adoption of ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. The fair value of each stock option grant is estimated on the date of grant using the Black‑Scholes option pricing model. Prior to September 2018, the Company historically was a private company and lacks sufficient company‑specific historical and implied volatility information for its shares. Therefore, it estimates its expected share price volatility based on the historical volatility of a group of publicly‑traded peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded share price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards as the Company has limited historical data to support the expected term assumption. The expected term of stock options granted to non‑employees is equal to the contractual term of the option award. The risk‑free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends on common shares and does not expect to pay any cash dividends in the foreseeable future. Stock-based compensation costs were $4.7 million and $2.0 million for the years ended December 31, 2019 and 2018, respectively.
Segment Information	Segment Information The Company is engaged solely in the discovery and development of novel antibody therapeutic products to treat cancer. Accordingly, the Company has determined that it operates in one operating segment.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with shareholders. The difference between net loss and comprehensive loss for the period presented in the accompanying financial statements was due to foreign currency translation.
Foreign Currency	Foreign Currency The financial statements of our Danish subsidiary with a functional currency other than the U.S. dollar are translated into U.S. dollars using period‑end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates during the period for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss), net of tax, in stockholders’ equity. Foreign currency transaction gains and losses are included in the results of operations in other income and expense, and totaled $(43,000) and $(97,000) for the years ended December 31, 2019 and 2018, respectively.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements - Adopted In July 2018, the FASB issued Accounting Standards Update No. 2018-09 (“ASU 2018-09”), Codification Improvements, which clarify, correct errors in, or make minor improvements to a variety of ASC topics. The changes in ASU 2018-09 are not expected to have a significant effect on current accounting practices. Some of the amendments in this update do not require transition guidance and will be effective upon this update. However, many of the updates do have transition guidance with effective dates for periods beginning after December 15, 2018. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In June 2018, the FASB issued ASU No. 2018‑07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share‑Based Payment Accounting (“ASU 2018‑07”). ASU 2018‑07 is intended to simplify aspects of share‑based compensation issued to non‑employees by making the guidance consistent with the accounting for employee share‑based compensation. ASU 2018‑07 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In February 2018, the FASB issued Accounting Standards Update No. 2018‑02, (“ASU 2018-02”), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018‑02 allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018‑07 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The adoption of this standard on January 1, 2019 did not have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued Accounting Standards Update No. 2016‑02 (“ASU 2016‑02”), Leases, which is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018 with early adoption permitted. Under ASU 2016‑02, lessees will be required to recognize for most leases, at the commencement date of the lease, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease measured on a discounted basis, and a right‑to‑use asset, which is an asset that represents the lessee’s right to use or control the use of a specified asset for the lease term. Topic 842 was subsequently amended by ASU 2017-13, Revenue and Leases: Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments; ASU 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; ASU No. 2018-11, Targeted Improvements and ASU No. 2018-20, Narrow Scope Improvements for Lessors. The Company adopted the new leasing standards using the modified retrospective transition approach as of January 1, 2019, with no restatement of prior periods or cumulative adjustment to retained earnings. An entity may choose to use either (1) its effective date or (2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company used the effective date as our date of initial application. Consequently, financial information was not updated and the disclosures required under the new standard are not provided for dates and periods before January 1, 2019. The new standard also provides a number of optional practical expedients in transition. The Company elected the package of practical expedients, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. Upon adoption of the new leasing standards, the Company recognized a lease liability of $1.8 million and a related right-of-use asset of $1.5 million with the difference being due to the elimination of previously reported deferred rent. The Company subsequently entered into two new lease agreements during the three months ended March 31, 2019, and recognized an incremental lease liability and related right-of-use asset of $0.9 million. Please refer to lease footnotes at Note 6 License Agreement And Commitments. Recently Issued Accounting Pronouncements – Not Yet Adopted In August 2018, the FASB issued Accounting Standards Update No. 2018-15 (“ASU 2018-15”), Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 clarifies certain aspects of ASU 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, which was issued in April 2015. Specifically, ASU 2018-14 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal use software (and hosting arrangements that include an internal-use software license). ASU 2018-15 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years with early adoption permitted. The Company is currently evaluating the impact its adoption may have on its consolidated financial statements .

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of cash equivalents measured at fair value on recurring basis	The following tables present the Company’s fair value hierarchy for its cash equivalents, which are measured at fair value on a recurring basis (in thousands): Fair Value Measurements at December 31, 2019 Using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ — $ 197,879 $ — $ 197,879 $ — $ 197,879 $ — $ 197,879
Schedule of property and equipment	Estimated Useful Life Furniture and fixtures 5 years Machinery and equipment 5 years Leasehold improvements Shorter of life of lease or 15 years

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
NET LOSS PER SHARE
Schedule of basic and diluted net loss per share	For the year ended December 31, 2019 2018 (in thousands, except share and per share amounts) Net loss (numerator) $ (81,028) $ (43,274) Weighted-average shares (denominator) 35,183,488 28,772,384 Basic and diluted net loss per share $ (2.30) $ (1.50)

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2019
ACCRUED LIABILITIES
Summary of accrued short-term liabilities	December 31, December 31, 2019 2018 (in thousands) Accrued milestone and royalty payments $ 354 $ 1,475 Accrued clinical costs 1,584 63 Accrued compensation and board fees 1,475 1,144 Accrued rent — 44 Accrued manufacturing costs 760 — Other 377 525 Total $ 4,550 $ 3,251

LICENSE AGREEMENTS AND COMMIT_2

LICENSE AGREEMENTS AND COMMITMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
LICENSE AGREEMENTS AND COMMITMENTS
Maturities of operating lease liabilities	Maturities of operating lease liabilities at December 31, 2019 were as follows (in thousands): Operating Leases at December 31, 2019 2020 $ 749 2021 753 2022 646 2023 539 Thereafter 77 Total lease payments 2,764 Less: Imputed interest (534) Total operating lease liabilities at December 31, 2019 $ 2,230
Future minimum lease payments, Prior to adoption of Topic 842	Future minimum lease payments, including imputed interest, under non-cancelable operating leases at December 31, 2018 were as follows (in thousands): Contractual Obligations at December 31, 2018 2019 $ 510 2020 616 2021 616 2022 616 2023 462 Thereafter 64 Total lease payments 2,884 Less: Imputed interest — Contractual obligations at December 31, 2018 $ 2,884

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2019
Share-Based Compensation Awards
Schedule of common stock options issued and outstanding	Weighted Weighted Aggregate average average intrinsic remaining exercise value contractual Options price (in thousands) life (years) Outstanding and expected to vest at December 31, 2018 3,357,873 $ 7.74 $ 43,224 7.90 Granted 648,000 $ 25.88 Outstanding and expected to vest at December 31, 2019 4,005,873 $ 10.67 $ 82,944 7.34 Exercisable at December 31, 2019 2,495,433 $ 5.31 $ 64,738 6.41
Schedule of restricted stock units issued and outstanding	Restricted Stock Units Outstanding and expected to vest at December 31, 2018 — Granted 10,296 Outstanding and expected to vest at December 31, 2019 10,296
Employees
Share-Based Compensation Awards
Schedule of assumptions that Company used to determine the fair value of the stock options granted	Year Ended Year Ended December 31, 2019 December 31, 2018 Risk-free interest rate 1.78 % 2.89 % Expected term (in years) 6.3 6.3 Expected volatility 60.6 % 57.8 % Expected dividend yield — % — %
Nonemployees
Share-Based Compensation Awards
Schedule of assumptions that Company used to determine the fair value of the stock options granted	Year Ended December 31, 2018 Risk-free interest rate 3.00 % Expected term (in years) 10.0 Expected volatility 62.7 % Expected dividend yield — %

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
INCOME TAXES
Schedule of domestic and foreign loss before income taxes	For The For The Year Ended Year Ended December 31, December 31, 2019 2018 (thousands) (thousands) United States $ (80,598) $ (42,456) Foreign (430) (818) Total $ (81,028) $ (43,274)
Schedule of difference between incomes taxes expected at U.S. federal statutory income tax rate and income taxes	December 31, 2019 December 31, 2018 (thousands) (thousands) Taxes on income at U.S. federal statutory rate $ (17,016) $ (9,127) State and local taxes, net of federal tax effects (11,022) (5,778) Effect of rate change (22) (9) Foreign tax rate differential (4) (8) Valuation allowance 33,984 16,376 Tax credits (5,924) (1,431) Other 4 (23) Total — —
Schedule of significant components of net deferred tax assets/(liabilities)	December 31, 2019 December 31, 2018 (thousands) (thousands) Deferred tax assets/(liabilities): Acquired intangibles $ 2,504 $ 2,682 Accrued bonus 153 — Unrealized foreign exchange loss (261) (163) Accrued royalty 415 415 Stock based compensation 2,594 981 Net operating loss carryforwards 51,649 25,285 Tax credit carryforwards 8,412 2,789 ROU asset (625) — Lease liability 711 — Other (63) 78 Total deferred tax assets/(liabilities) 65,489 32,067 Valuation allowance (65,489) (32,067) Net deferred tax assets/(liabilities) — —

QUARTERLY CONSOLIDATED FINANC_2

QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited)
Schedule of quarterly consolidated financial data	(In thousands, except per share amounts) 2019 March 31 June 30 September 30 December 31 Loss from operations $ (16,253) $ (18,634) $ (24,359) $ (23,758) Net loss (15,934) (18,036) (23,922) (23,136) Net loss per share - basic and diluted $ (0.47) $ (0.53) $ (0.70) $ (0.60) 2018 March 31 June 30 September 30 December 31 Loss from operations $ (7,479) $ (10,258) $ (11,415) $ (14,078) Net loss (7,483) (10,305) (11,426) (14,060) Net loss per share - basic and diluted $ (0.28) $ (0.38) $ (0.42) $ (0.42)

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Issuance of stock
Accumulated deficit	$ 165,863	$ 84,835
Cash and cash equivalents	$ 207,136	$ 147,840

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair Value Measurement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair value measurements
Level 1 to Level 2 Transfers	$ 0	$ 0
Level 2 to Level 1 Transfers	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Recurring
Fair value measurements
Cash equivalents	197,879
Recurring | Money market funds
Fair value measurements
Cash equivalents	197,879	$ 0
Recurring | Level 2
Fair value measurements
Cash equivalents	197,879
Recurring | Level 2 | Money market funds
Fair value measurements
Cash equivalents	$ 197,879

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Operating Leases (Details)	Dec. 31, 2019USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Residual value guarantees	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment
Depreciation and amortization expense	$ 166,000	$ 29,000
Furniture and fixtures
Property and Equipment
Estimated Useful Life	5 years
Machinery and equipment
Property and Equipment
Estimated Useful Life	5 years
Leasehold improvements | Maximum
Property and Equipment
Estimated Useful Life	15 years

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other policies (Details)	12 Months Ended
	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Research and development	$ 63,492,000	$ 34,269,000
Stock-based compensation	$ 4,657,000	1,966,000
Number of operating segments | segment	1
Foreign currency transaction gains and losses	$ (43,000)	$ (97,000)

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently issued accounting pronouncements (Details) $ in Thousands	Jan. 01, 2019USD ($)	Mar. 31, 2019USD ($)lease	Dec. 31, 2019USD ($)
New accounting pronouncements
Lease liability			$ 2,230
Operating lease right-of-use assets			$ 1,989
Number of lease agreements entered into during the period | lease		2
Increase in lease liability upon entering into new lease agreements		$ 900
Increase in right-of-use assets upon entering into new lease agreements		$ 900
ASU 2016-02
New accounting pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true
New Accounting Pronouncement or Change in Accounting Principle, Prior Period Not Restated	true
Lease, Practical Expedients, Package	true
ASU 2016-02 | Adjustment
New accounting pronouncements
Lease liability	$ 1,800
Operating lease right-of-use assets	$ 1,500

NET LOSS PER SHARE - Basic and

NET LOSS PER SHARE - Basic and diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
NET LOSS PER SHARE
Net loss (numerator)	$ (23,136)	$ (23,922)	$ (18,036)	$ (15,934)	$ (14,060)	$ (11,426)	$ (10,305)	$ (7,483)	$ (81,028)	$ (43,274)
Weighted-average shares (denominator)									35,183,488	28,772,384
Basic and diluted net loss per share (in dollars per share)	$ (0.60)	$ (0.70)	$ (0.53)	$ (0.47)	$ (0.42)	$ (0.42)	$ (0.38)	$ (0.28)	$ (2.30)	$ (1.50)

NET LOSS PER SHARE - Anti-dilut

NET LOSS PER SHARE - Anti-dilutive securities (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock options
LOSS PER SHARE
Potentially dilutive securities outstanding	4,005,873	3,357,873

ACCRUED LIABILITIES (Details)

ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued short term liabilities
Accrued milestone and royalty payments	$ 354	$ 1,475
Accrued clinical costs	1,584	63
Accrued compensation and board fees	1,475	1,144
Accrued rent		44
Accrued manufacturing costs	760
Other	377	525
Total	$ 4,550	$ 3,251

LICENSE AGREEMENTS AND COMMIT_3

LICENSE AGREEMENTS AND COMMITMENTS (Details)	Dec. 31, 2019agreement
LICENSE AGREEMENTS AND COMMITMENTS
Number of license agreements	2

LICENSE AGREEMENTS AND COMMIT_4

LICENSE AGREEMENTS AND COMMITMENTS - MSK License Agreement (Details) - MSK License Agreement - USD ($) $ in Thousands	Aug. 20, 2015	Dec. 31, 2019	Dec. 31, 2016	Dec. 31, 2018
Agreements
Issuance of common stock to strategic partner (in shares)	1,428,500
Annual minimum royalties payable from fifth anniversary	$ 80
Expensed minimum royalty payments			$ 1,200
Clinical milestones potentially due	2,450
Regulatory milestones potentially due	9,000
Sales-based milestones potentially due	$ 20,000
Milestone expenses		$ 75
Milestone payment		725
Accrued short-term liabilities
Agreements
Short-term accrued minimum royalties		29
Accrued milestone payments, current		225		$ 875
Accrued long-term liabilities
Agreements
Long-term accrued minimum royalties		1,171		1,200
Accrued milestone payments, noncurrent		$ 300		$ 300

LICENSE AGREEMENTS AND COMMIT_5

LICENSE AGREEMENTS AND COMMITMENTS - CD33 License Agreement (Details) - CD33 License Agreement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 13, 2017
Agreements
Annual minimum royalties payable				$ 40
Annual minimum royalties payable from tenth anniversary				60
Clinical and regulatory milestones potentially due				1,050
Sales-based milestones potentially due				$ 7,500
Clinical milestone expense			$ 550
Clinical milestone payment	$ 0	$ 0
Accrued short-term liabilities
Agreements
Accrued milestone payments, current	100
Accrued long-term liabilities
Agreements
Accrued milestone payments, noncurrent	$ 450	$ 550

LICENSE AGREEMENTS AND COMMIT_6

LICENSE AGREEMENTS AND COMMITMENTS - MabVax Sublicense Agreement (Details) - MabVax Sublicense Agreement - USD ($) $ in Thousands	Jun. 27, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Agreements
License fee paid	$ 700	$ 600	$ 1,300
License fee accrued				$ 600
Development milestone payments due	$ 1,400

LICENSE AGREEMENTS AND COMMIT_7

LICENSE AGREEMENTS AND COMMITMENTS - Other agreements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)employeeagreement	Dec. 31, 2018USD ($)
Agreements
Research and development	$ 63,492	$ 34,269
CFAs
Agreements
Number of service agreements | agreement	2
CD33-SRA
Agreements
Research service period	2 years
Research and development	$ 6,800	$ 5,800
Researchers, Employees of MSK | MDSA
Agreements
Number of individuals | employee	5

LICENSE AGREEMENTS AND COMMIT_8

LICENSE AGREEMENTS AND COMMITMENTS - Lease agreements (Details) $ in Thousands	1 Months Ended
	Feb. 28, 2019USD ($)ft²	Feb. 28, 2018	Jan. 31, 2018USD ($)
Laboratory, New Jersey
Leases
Leased area (in square feet) | ft²	4,500
Lease term	3 years
Option to extend	true
Option to extend, period	2 years
Fixed rent payable per annum	$ 144
Lease payable per month	12
Corporate headquarters, New York
Leases
Lease term			5 years
Fixed rent payable per annum			$ 384
Lease payable per month			$ 32
Office space, Denmark
Leases
Lease term		3 years
Lease payable per month	$ 19

LICENSE AGREEMENTS AND COMMIT_9

LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases
Total operating lease costs	$ 676
Rental expense for operating leases		$ 394
Cash paid for amounts included in the measurement of lease liabilities	606
Research and development expense
Leases
Total operating lease costs	493
General and administrative expense
Leases
Total operating lease costs	$ 183
Rental expense for operating leases		$ 394

LICENSE AGREEMENTS AND COMMI_10

LICENSE AGREEMENTS AND COMMITMENTS - Lease maturities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Future minimum commitments under all non-cancelable operating leases
2020	$ 749
2021	753
2022	646
2023	539
Thereafter	77
Total lease payments	2,764
Less: Imputed interest	(534)
Total operating lease liabilities at December 31, 2019	$ 2,230

LICENSE AGREEMENTS AND COMMI_11

LICENSE AGREEMENTS AND COMMITMENTS - 2018 Lease maturities (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future minimum commitments under non-cancelable operating leases, 2018
2019	$ 510
2020	616
2021	616
2022	616
2023	462
Thereafter	64
Total lease payments	2,884
Contractual obligations at December 31, 2018	$ 2,884

LICENSE AGREEMENTS AND COMMI_12

LICENSE AGREEMENTS AND COMMITMENTS - Lease term and discount rate (Details)	Dec. 31, 2019
LICENSE AGREEMENTS AND COMMITMENTS
Weighted average remaining lease term	3 years 9 months 29 days
Weighted average discount rate	11.00%

STOCKHOLDERS' EQUITY - Authoriz

STOCKHOLDERS' EQUITY - Authorized, Common and Preferred Stock (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)Vote$ / sharesshares	Dec. 31, 2018$ / sharesshares
STOCKHOLDERS' EQUITY
Total shares authorized	105,500,000	105,500,000
Common stock, authorized shares	100,000,000	100,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, authorized shares	5,500,000	5,500,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Number of votes per common share | Vote	1
Common stock dividends issued | $	$ 0
Common stock, shares issued	39,728,416	34,193,666
Preferred stock, shares issued	0	0

STOCKHOLDERS' EQUITY - Stock gr

STOCKHOLDERS' EQUITY - Stock grant agreements with non-employees, Stock (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2015individualshares	Dec. 31, 2020individualshares	Dec. 31, 2019individualUSD ($)shares	Dec. 31, 2018shares	Dec. 31, 2017shares	Dec. 31, 2016shares	Dec. 31, 2015shares
Nonemployees | Researchers, Employees of MSK
Share-Based Compensation Awards
Shares agreed to be issued	2,800,000
Number of individuals	2		1
Number of non-employee physicians - not used | individual	2		2
Issuance of common stock to nonemployees (in shares)				544,000
Nonemployees | Researchers, Employees of MSK | Forecast
Share-Based Compensation Awards
Number of individuals | individual		2,020
Common Stock
Share-Based Compensation Awards
Issuance of common stock to nonemployees (in shares)			400,000	544,000
Common Stock | Nonemployees | Researchers, Employees of MSK
Share-Based Compensation Awards
Issuance of common stock to nonemployees (in shares)			400,000		448,000	448,000	560,000
Common Stock | Nonemployees | Researchers, Employees of MSK | Forecast
Share-Based Compensation Awards
Issuance of common stock to nonemployees (in shares)		400,000

STOCKHOLDERS' EQUITY - Stock _2

STOCKHOLDERS' EQUITY - Stock grant agreements with non employees, Stock options (Details) - shares	1 Months Ended	12 Months Ended
	Apr. 30, 2018	Dec. 31, 2019
Share-Based Compensation Awards
Granted (in shares)		648,000
Nonemployees
Share-Based Compensation Awards
Granted (in shares)		0
2015 Plan | Nonemployees
Share-Based Compensation Awards
Granted (in shares)	72,373
Vesting period	4 years
Term of award	10 years
2015 Plan | Nonemployees | Tranche one
Share-Based Compensation Awards
Vesting period	12 months
Vesting (as a percent)	25.00%
2015 Plan | Nonemployees | Tranche two
Share-Based Compensation Awards
Vesting period	3 years

STOCKHOLDERS' EQUITY - Issuance

STOCKHOLDERS' EQUITY - Issuance of common stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Issuance of stock
Proceeds from issuance of common stock, net of issuance costs			$ 134,704	$ 99,765
Common Stock
Issuance of stock
Shares issued (in shares)			5,134,750	6,900,000
Common Stock | IPO
Issuance of stock
Shares issued (in shares)		6,900,000
Share price (in dollars per share)		$ 16
Gross Proceeds From Issuance Of Shares		$ 99,507
Proceeds from issuance of common stock, net of issuance costs		$ 10,900
Common Stock | Secondary Public Offering
Issuance of stock
Shares issued (in shares)	5,134,750
Share price (in dollars per share)	$ 28
Gross Proceeds From Issuance Of Shares	$ 134,704
Proceeds from issuance of common stock, net of issuance costs	$ 9,100

SHARE-BASED COMPENSATION - 2015

SHARE-BASED COMPENSATION - 2015 Plan (Details) - 2015 Plan - shares	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2018
Share-Based Compensation Awards
Shares reserved for issuance pursuant to the plan	4,500,000
Shares available for grant		0
Stock options | Employees and nonemployees owning less than 10% of voting power
Share-Based Compensation Awards
Vesting period	4 years

SHARE-BASED COMPENSATION - 2018

SHARE-BASED COMPENSATION - 2018 Plan (Details) - shares	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2019
Share-Based Compensation Awards
Options granted (in shares)		648,000
2018 Plan
Share-Based Compensation Awards
Shares reserved for issuance pursuant to the plan	5,500,000
Annual increase on share reserve (as a percent)	4.00%
2018 Plan | Stock options | Employees and nonemployees owning less than 10% of voting power
Share-Based Compensation Awards
Term of award	10 years
Vesting period	4 years
2018 Plan | Stock options | Participants owning more than 10% of voting power
Share-Based Compensation Awards
Term of award	5 years
2018 Plan | Stock options | Employee owning more than 10% of voting power | Minimum
Share-Based Compensation Awards
Ownership (as a percent)	10.00%
Option price as percentage of fair market value of common stock on the date of grant	110.00%

SHARE-BASED COMPENSATION - Expe

SHARE-BASED COMPENSATION - Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-Based Compensation Awards
Stock-based compensation expenses	$ 4,657	$ 1,381
Stock options | Employees
Share-Based Compensation Awards
Stock-based compensation expenses	4,581	1,381
Stock options | Employees | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	933	276
Stock options | Employees | General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	3,647	1,105
RSUs
Share-Based Compensation Awards
Stock-based compensation expenses	76	$ 0
RSUs | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	69
RSUs | General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	7
RSUs | Employees
Share-Based Compensation Awards
Stock-based compensation expenses	76
RSUs | Employees | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	69
RSUs | Employees | General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 7

SHARE-BASED COMPENSATION - Stoc

SHARE-BASED COMPENSATION - Stock Option Valuation (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock Option Valuation
Granted (in shares)	648,000
Nonemployees
Stock Option Valuation
Granted (in shares)	0
Stock options | Employees
Stock Option Valuation
Risk-free interest rate	1.78%	2.89%
Expected term (in years)	6 years 3 months 18 days	6 years 3 months 18 days
Expected volatility	60.60%	57.80%
Stock options | Nonemployees
Stock Option Valuation
Risk-free interest rate		3.00%
Expected term (in years)		10 years
Expected volatility		62.70%

SHARE-BASED COMPENSATION - St_2

SHARE-BASED COMPENSATION - Stock options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Options
Outstanding at beginning of period (in shares)	3,357,873
Granted (in shares)	648,000
Outstanding at end of period (in shares)	4,005,873	3,357,873
Exercisable at end of period (in shares)	2,495,433
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)	$ 7.74
Granted (in dollars per share)	25.88
Outstanding at end of period (in dollars per share)	10.67	$ 7.74
Exercisable at end of period (in dollars per share)	$ 5.31
Aggregate intrinsic value and Weighted average remaining contractual life (years)
Outstanding (in dollars)	$ 82,944	$ 43,224
Exercisable (in dollars)	$ 64,738
Outstanding (in years)	7 years 4 months 2 days	7 years 10 months 24 days
Exercisable (in years)	6 years 4 months 28 days
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 14.92	$ 9.58

SHARE-BASED COMPENSATION - Unre

SHARE-BASED COMPENSATION - Unrecognized compensation (Details) - Stock options - Employees - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Unrecognized compensation related to employee stock options
Unrecognized compensation	$ 15,942	$ 10,848
Expected vesting period	2 years 8 months 19 days	2 years 9 months 26 days

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock Unit Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-Based Compensation Awards
Stock-based compensation expenses	$ 4,657	$ 1,381
RSUs
Share-Based Compensation Awards
Stock-based compensation expenses	$ 76	$ 0
Restricted stock units issued and outstanding
Granted (in shares)	10,296
Outstanding and expected to vest at end of period (in shares)	10,296
Weighted average fair value of units granted in period (in dollars per share)	$ 23.11
Unrecognized compensation	$ 163
Expected vesting period	2 years 18 days
RSUs | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 69
RSUs | General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 7

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2016	Dec. 31, 2019	Dec. 31, 2018
MSK | MSK License Agreement, the CD33 License Agreement, CTA, CFAs, SRA and MDSA
Related party transactions
Expenses		$ 6,832	$ 5,761
Due to related parties		4,171	4,475
Weco Group | Lease Agreement
Related party transactions
Expenses		$ 0	$ 44
Lease payable per month	$ 4
Notice period to terminate lease	3 months
Future rent commitment	$ 12

INCOME TAXES - Expense (Details

INCOME TAXES - Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Domestic and foreign loss before income taxes:
United States	$ (80,598)	$ (42,456)
Foreign	(430)	(818)
Total losses before taxes	(81,028)	(43,274)
Income tax expense
Current income taxes	0	0
Deferred income taxes	$ 0	$ 0

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
U.S. federal corporate tax rate (as a percent)	21.00%	21.00%
Difference between income taxes expected at U.S. federal statutory income tax rate and income taxes provided:
Taxes on income at U.S. federal statutory rate	$ (17,016)	$ (9,127)
State and local taxes, net of federal tax effects	(11,022)	(5,778)
Effect of rate change	(22)	(9)
Foreign tax rate differential	(4)	(8)
Valuation allowance	33,984	16,376
Tax credits	(5,924)	(1,431)
Other	$ 4	$ (23)
U.S. federal corporate tax rate (as a percent)	21.00%	21.00%

INCOME TAXES - Deferred tax ass

INCOME TAXES - Deferred tax assets/(liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets/(liabilities)::
Acquired intangibles	$ 2,504	$ 2,682
Accrued bonus	153
Unrealized foreign exchange (gain)	(261)	(163)
Accrued royalty	415	415
Stock based compensation	2,594	981
Net operating loss carryforwards	51,649	25,285
Tax credit carryforwards	8,412	2,789
ROU asset	(625)
Lease liability	711
Other		78
Other liabilities	(63)
Total deferred tax assets/(liabilities)	65,489	32,067
Valuation allowance	$ (65,489)	$ (32,067)

INCOME TAXES - Uncertain tax po

INCOME TAXES - Uncertain tax positions (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
INCOME TAXES
Uncertain tax position	$ 0	$ 0

INCOME TAXES - Net Operating Lo

INCOME TAXES - Net Operating Loss Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
U.S. federal
Operating Loss Carryforwards
Net operating loss carryforwards	$ 147,839
Operating loss carryforward, expiring through 2037	29,909
Operating loss carryforward, indefinte	117,930
State
Operating Loss Carryforwards
Net operating loss carryforwards	148,608
New York City
Operating Loss Carryforwards
Net operating loss carryforwards	148,608
Danish
Operating Loss Carryforwards
Net operating loss carryforwards	$ 1,540

INCOME TAXES - Tax Credit Carry

INCOME TAXES - Tax Credit Carryforwards (Details) $ in Thousands	Dec. 31, 2019USD ($)
U.S. federal
Tax credit carryforward
Tax credit	$ 8,412

OTHER BENEFITS (Details)

OTHER BENEFITS (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
OTHER BENEFITS
Employer matching contribution to defined contribution plan (as a percent)	0.00%	0.00%

QUARTERLY CONSOLIDATED FINANC_3

QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
QUARTERLY CONSOLIDATED FINANCIAL DATA (unaudited)
Loss from operations	$ (23,758)	$ (24,359)	$ (18,634)	$ (16,253)	$ (14,078)	$ (11,415)	$ (10,258)	$ (7,479)	$ (83,004)	$ (43,230)
Net loss	$ (23,136)	$ (23,922)	$ (18,036)	$ (15,934)	$ (14,060)	$ (11,426)	$ (10,305)	$ (7,483)	$ (81,028)	$ (43,274)
Basic and diluted net loss per share (in dollars per share)	$ (0.60)	$ (0.70)	$ (0.53)	$ (0.47)	$ (0.42)	$ (0.42)	$ (0.38)	$ (0.28)	$ (2.30)	$ (1.50)