Y-mAbs Therapeutics (YMAB) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-38650
Entity Registrant Name	Y-mAbs Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4619612
Entity Address, Address Line One	230 Park Avenue
Entity Address, Address Line Two	Suite 3350
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10169
City Area Code	646
Local Phone Number	885-8505
Title of 12(b) Security	Common Stock
Trading Symbol	YMAB
Security Exchange Name	NASDAQ
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 Common Stock, Shares Outstanding		40,513,657
Entity Central Index Key	0001722964
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
CURRENT ASSETS
Cash and cash equivalents	$ 131,267	$ 207,136
Other current assets	1,942	4,819
Total current assets	133,209	211,955
Property and equipment, net	1,888	2,052
Operating lease right-of-use assets	5,123	1,989
Other assets	2,975	370
TOTAL ASSETS	143,195	216,366
LIABILITIES
Accounts payable	10,320	8,520
Accrued liabilities	7,570	4,550
Operating lease liabilities, current portion	1,887	516
Total current liabilities	19,777	13,586
Accrued milestone and royalty payments	2,466	1,921
Operating lease liabilities, long-term portion	2,517	1,714
Other liabilities	1,923	242
TOTAL LIABILITIES	26,683	17,463
Commitments and contingencies (Note 6)
STOCKHOLDERS' EQUITY
Preferred stock, $0.0001 par value, 5,500,000 shares authorized at September 30, 2020 and December 31, 2019; none issued at September 30, 2020 and December 31, 2019
Common stock, $0.0001 par value, 100,000,000 shares authorized at September 30, 2020 and December 31, 2019; 40,472,435 and 39,728,416 shares issued at September 30, 2020 and December 31, 2019, respectively	4	4
Additional paid in capital	381,803	364,712
Accumulated other comprehensive income (loss)	(28)	50
Accumulated deficit	(265,267)	(165,863)
TOTAL STOCKHOLDERS' EQUITY	116,512	198,903
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 143,195	$ 216,366

Consolidated Balance Sheets (pa

Consolidated Balance Sheets (parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
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	40,472,435	39,728,416

Consolidated Statements of Net

Consolidated Statements of Net Loss and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
OPERATING EXPENSES
Research and development	$ 21,005	$ 19,660	$ 69,686	$ 46,665
General and administrative	11,636	4,699	30,155	12,581
Total operating expenses	32,641	24,359	99,841	59,246
Loss from operations	(32,641)	(24,359)	(99,841)	(59,246)
OTHER INCOME, NET
Interest and other income / (expenses), net	(191)	437	437	1,354
NET LOSS	(32,832)	(23,922)	(99,404)	(57,892)
Other comprehensive income
Foreign currency translation	(12)	134	(78)	124
COMPREHENSIVE LOSS	$ (32,844)	$ (23,788)	$ (99,482)	$ (57,768)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.82)	$ (0.70)	$ (2.49)	$ (1.69)
Weighted average common shares outstanding, basic and diluted	40,187,173	34,371,927	39,971,766	34,253,739

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, 2018	$ 3	$ 225,352	$ 7	$ (84,835)	$ 140,527
Balance at the beginning of period (in shares) at Dec. 31, 2018	34,193,666
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		864			864
Foreign currency translation			56		56
Net loss				(15,934)	(15,934)
Balance at the end of period at Mar. 31, 2019	$ 3	226,216	63	(100,769)	125,513
Balance at the end of period (in shares) at Mar. 31, 2019	34,193,666
Balance at the beginning of period at Dec. 31, 2018	$ 3	225,352	7	(84,835)	140,527
Balance at the beginning of period (in shares) at Dec. 31, 2018	34,193,666
Increase (Decrease) in Stockholders' Equity
Net loss					(57,892)
Balance at the end of period at Sep. 30, 2019	$ 3	228,532	131	(142,727)	85,939
Balance at the end of period (in shares) at Sep. 30, 2019	34,593,666
Balance at the beginning of period at Dec. 31, 2018	$ 3	225,352	7	(84,835)	140,527
Balance at the beginning of period (in shares) at Dec. 31, 2018	34,193,666
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
Balance at the beginning of period at Mar. 31, 2019	$ 3	226,216	63	(100,769)	125,513
Balance at the beginning of period (in shares) at Mar. 31, 2019	34,193,666
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		971			971
Foreign currency translation			(66)		(66)
Net loss				(18,036)	(18,036)
Balance at the end of period at Jun. 30, 2019	$ 3	227,187	(3)	(118,805)	108,382
Balance at the end of period (in shares) at Jun. 30, 2019	34,193,666
Increase (Decrease) in Stockholders' Equity
Issuance of common stock to non-employees (in shares)	400,000
Stock-based compensation expense		1,345			1,345
Foreign currency translation			134		134
Net loss				(23,922)	(23,922)
Balance at the end of period at Sep. 30, 2019	$ 3	228,532	131	(142,727)	85,939
Balance at the end of period (in shares) at Sep. 30, 2019	34,593,666
Balance at the beginning of period at Dec. 31, 2019	$ 4	364,712	50	(165,863)	198,903
Balance at the beginning of period (in shares) at Dec. 31, 2019	39,728,416
Increase (Decrease) in Stockholders' Equity
Exercise of stock options		370			370
Exercise of stock options (in shares)	25,778
Stock-based compensation expense		2,211			2,211
Stock-based compensation expense (in shares)	3,429
Foreign currency translation			25		25
Net loss				(26,179)	(26,179)
Balance at the end of period at Mar. 31, 2020	$ 4	367,293	75	(192,042)	175,330
Balance at the end of period (in shares) at Mar. 31, 2020	39,757,623
Balance at the beginning of period at Dec. 31, 2019	$ 4	364,712	50	(165,863)	$ 198,903
Balance at the beginning of period (in shares) at Dec. 31, 2019	39,728,416
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)					83,694
Net loss					$ (99,404)
Balance at the end of period at Sep. 30, 2020	$ 4	381,803	(28)	(265,267)	116,512
Balance at the end of period (in shares) at Sep. 30, 2020	40,472,435
Balance at the beginning of period at Mar. 31, 2020	$ 4	367,293	75	(192,042)	175,330
Balance at the beginning of period (in shares) at Mar. 31, 2020	39,757,623
Increase (Decrease) in Stockholders' Equity
Issuance of common stock to non-employees		8,707			8,707
Issuance of common stock to non-employees (in shares)	256,896
Stock-based compensation expense		2,455			2,455
Foreign currency translation			(91)		(91)
Net loss				(40,393)	(40,393)
Balance at the end of period at Jun. 30, 2020	$ 4	378,455	(16)	(232,435)	146,008
Balance at the end of period (in shares) at Jun. 30, 2020	40,014,519
Increase (Decrease) in Stockholders' Equity
Exercise of stock options		215			215
Exercise of stock options (in shares)	57,916
Issuance of common stock to non-employees (in shares)	400,000
Stock-based compensation expense		3,133			3,133
Foreign currency translation			(12)		(12)
Net loss				(32,832)	(32,832)
Balance at the end of period at Sep. 30, 2020	$ 4	$ 381,803	$ (28)	$ (265,267)	$ 116,512
Balance at the end of period (in shares) at Sep. 30, 2020	40,472,435

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (99,404)	$ (57,892)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	279	87
Stock-based compensation	7,799	3,180
Non-cash expense in connection with equity issuance to MSK/MIT	1,331
Non-cash expense in connection with equity issuance to inventors	7,376
Foreign currency transactions	(62)	123
Changes in assets and liabilities:
Other current assets	1,939	2,262
Other assets	2	(131)
Accounts payable	1,800	1,031
Accrued liabilities and other	5,404	2,422
NET CASH USED IN OPERATING ACTIVITIES	(73,536)	(48,918)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of property and equipment	(131)	(818)
Loans to inventors	(2,610)
NET CASH USED IN INVESTING ACTIVITIES	(2,741)	(818)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercised stock options	585
NET CASH PROVIDED BY FINANCING ACTIVITIES	585
Effect of exchange rates on cash and cash equivalents	(177)	57
NET DECREASE IN CASH AND CASH EQUIVALENTS	(75,869)	(49,679)
Cash and cash equivalents at the beginning of period	207,136	147,871
Cash and cash equivalents at the end of period	131,267	98,192
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Property and equipment purchases in accounts payable		752
Right-of-use assets obtained in exchange for lease obligations	$ 2,679	$ 901

ORGANIZATION AND DESCRIPTION OF

ORGANIZATION AND DESCRIPTION OF BUSINESS	9 Months Ended
	Sep. 30, 2020
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, New York and was incorporated on April 30, 2015 under the laws of the State of Delaware.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2020
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; dependence on key personnel; compliance with government regulations and the need to obtain additional financing. The Company’s drug candidates currently under development will require significant additional research and development efforts, including extensive preclinical 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 various stages of development. 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 negative cash flows from operations since inception and had an accumulated deficit of $265.3 million as of September 30, 2020 and $165.9 million as of December 31, 2019. Through September 30, 2020, the Company has funded its operations through proceeds from sales of shares of its common stock, including its initial public offering in September 2018 and its secondary public offering in November 2019. 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. As of September 30, 2020, the Company had cash and cash equivalents of $131.3 million. As of the issuance date of the quarterly financial statements as of and for the nine months ended September 30, 2020, the Company expects that its cash and cash equivalents at September 30, 2020 will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next twelve months, irrespective of whether any product approvals are obtained. The Company may raise additional capital to fund future operations through the sale of its equity securities, incurring debt, entering into licensing or collaboration agreements with partners, grants or other sources of financing. Sufficient funds may not be available to the Company on attractive terms or at all when needed from equity or debt financing. If FDA approvals for naxitamab or omburtamab do not occur or are significantly delayed, and the Company is unable to obtain additional financing from these or other sources when needed, it will likely be necessary to take other actions to enhance its liquidity position which may include significantly reducing the current rate of spending through delaying, scaling back current operations, or suspending certain research and development programs and other operational programs. The accompanying unaudited 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”) for interim financial information, Accounting Standards Codification (“ASC”) Topic 270-10 and with the instructions to Form 10-Q. Accordingly, these financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements include all adjustments (consisting only of normal recurring nature) necessary in the judgment of management for a fair statement of the results for the periods presented. All intercompany balances and transactions have been eliminated. The Company has evaluated subsequent events through the date of this filing. Operating results for the three and nine-month periods ended September 30, 2020 are not necessarily indicative of the results that may be expected for the year ended December 31, 2020, any other interim periods, or any future year or period. The December 31, 2019 consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. You should read these unaudited interim condensed consolidated financial statements in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2020
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 3—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Our critical accounting policies are detailed in our Annual Report on Form 10-K for the year ended December 31, 2019. Effective January 1, 2020, the Company adopted 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. The adoption of ASU 2018-15 did not have a material impact on the Company’s consolidated financial statements. 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. 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. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. ​ • 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. The following tables present the Company’s fair value hierarchy for its financial instruments, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at September 30, 2020 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ For the quarter ended September 30, 2020, there were no transfers Level 3 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, and the valuation of 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. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including expenses, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international markets. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates. Segment Information The Company is engaged solely in the discovery and development of novel antibody-based therapeutic products for the treatment of cancer. Accordingly, the Company has determined that it operates in one operating segment. Recently Issued Accounting Pronouncements – Adopted In August 2018, the FASB issued Accounting Standards Update No. 2018 -13 (“ASU2018-13”), Fair Value Measurement (Topic 820) Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 allows to remove the reasons for transfer between Level 1 and Level 2 assets, and adds the changes in unrealized gains and losses for recurring level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years with early adoption permitted. The adoption of this standard on January 1, 2020 did not have a material impact on our consolidated financial statements and related disclosures. 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 2018-15 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 adoption of this standard on January 1, 2020 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 all 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 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 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. Please reference Note 6—License Agreement and Commitments for details.

NET LOSS PER SHARE

NET LOSS PER SHARE	9 Months Ended
	Sep. 30, 2020
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 income or 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ Nine months ended September 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ (in thousands, except per share amounts) ​ ​ ​ ​ ​ Net loss (numerator) ​ $ (32,832) ​ $ (23,922) ​ $ (99,404) ​ $ (57,892) ​ Weighted-average shares (denominator) ​ 40,187 ​ 34,372 ​ 39,972 ​ 34,254 ​ Basic and diluted net loss per share ​ $ (0.82) ​ $ (0.70) ​ $ (2.49) ​ $ (1.69) ​ ​ Potentially dilutive securities excluded from the computation of diluted earnings per share relate to stock options outstanding and unvested restricted shares and RSUs and totaled 5,056,288 shares as of September 30, 2020 and 4,124,169 shares as of September 30, 2019, and were excluded because including them would have an anti-dilutive impact.

ACCRUED LIABILITIES

ACCRUED LIABILITIES	9 Months Ended
	Sep. 30, 2020
ACCRUED LIABILITIES
ACCRUED LIABILITIES	NOTE 5—ACCRUED LIABILITIES Accrued short-term liabilities at September 30, 2020 and December 31, 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 ​ 2019 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ Accrued licensing, milestone and royalty payments ​ $ 1,334 ​ $ 354 Accrued clinical costs ​ 729 ​ 1,584 Accrued compensation and board fees ​ 3,853 ​ 1,475 Accrued manufacturing costs ​ ​ 1,319 ​ ​ 760 Other ​ 335 ​ 377 Total ​ $ 7,570 ​ $ 4,550 ​

LICENSE AGREEMENTS AND COMMITME

LICENSE AGREEMENTS AND COMMITMENTS	9 Months Ended
	Sep. 30, 2020
LICENSE AGREEMENTS AND COMMITMENTS
LICENSE AGREEMENTS AND COMMITMENTS	NOTE 6—LICENSE AGREEMENTS AND COMMITMENTS As of September 30, 2020, the Company has entered into two license agreements and certain other agreements with Memorial Sloan Kettering Cancer Center (“MSK”). The license agreements, as previously disclosed in our annual report on Form 10-K, are the MSK License and the CD33 License Agreement. In addition, the Company has entered into the SADA License Agreement with MSK and Massachusetts Institute of Technology (“MIT”). Through a Settlement and Assumption and Assignment of the MSK License and Y-mAbs Sublicense Agreement (“SAAA”) with MabVax, Inc. (“MabVax”) and MSK, the Company has established a direct license with MSK relating to the GD2-GD3 Vaccine, which was originally sublicensed by the Company in 2018 from MabVax. These license agreements with MSK and MIT 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 and MIT. Certain of the payments are contingent milestone and royalty payments, as disclosed in the table below. Amounts disclosed in Note 5 for accrued milestone and royalty payments are inclusive of obligations under the MSK License, CD33 License Agreement and SADA License Agreement, collectively. We have the following significant license agreements and related commitments which include all obligations that have been paid or accrued as of and for the period ending September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Expense Expense Expense Expense Accrued liabilities Accrued liabilities Accrued liabilities Accrued liabilities Agreements ​ Nine months ended September 2020 ​ Nine months ended September 2020 ​ Nine months ended September 2019 ​ Three months ended September 2020 ​ Three months ended September 2019 ​ Current as of September 2020 ​ Non-current as of September 2020 ​ Current as of December 2019 ​ Non-current as of December 2019 MSK ​ ​ $ 80,000 ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ 234,000 ​ ​ $ 1,411,000 ​ ​ $ 254,000 ​ ​ $ 1,471,000 CD33 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 100,000 ​ ​ 450,000 ​ ​ 100,000 ​ ​ 450,000 MabVax ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ The below table represents the maximum clinical, regulatory or sales-based miletones as reflected within the agreements, certain of which have been paid in prior periods or are accrued as presented in the table above: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum Agreements ​ Clinical Milestones ​ Regulatory Milestones ​ Sales-based milestones ​ MSK ​ ​ $ 2,450,000 ​ ​ $ 9,000,000 ​ ​ $ 20,000,000 ​ CD33 ​ ​ 550,000 ​ ​ 500,000 ​ ​ 7,500,000 ​ MabVax ​ ​ 200,000 ​ ​ 1,200,000 ​ ​ — ​ ​ Minimum royalties and certain clinical milestones that become due based upon the passage of time under the CD33 License Agreement and the MabVax Agreement are not recorded as a liability as the Company does not consider such obligations to be probable as of September 30, 2020. ​ SADA License Agreement On April 15, 2020, we entered into a license agreement (the “SADA License Agreement”) with MSK and Massachusetts Institute of Technology (“MIT”) that grants us an exclusive worldwide, sublicensable license to MSK’s and MIT’s rights to certain patent and intellectual property 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 using the SADA BiDE Pre-targeted Radioimmunotherapy Platform (“SADA technology”). We have assessed the licensing and other rights acquired and given the lack of outputs upon acquisition and that no employees were acquired, among other factors, we have concluded that the licensing rights represented an asset acquisition. The patents and patent applications covered by this agreement are directed, in part, to the SADA technology, as well as a number of SADA constructs developed by MSK. Upon entering into the SADA License Agreement and in exchange for the licenses granted thereunder, we concluded that the technology acquired under the licensing arrangement had no alternative future use. This conclusion was based on consideration of the rights conveyed under the agreement, extent of further development necessary and presence of uncertainty prior to obtaining regulatory approval for any product. Accordingly, we expensed and paid MSK and MIT an upfront payment of $1,995,000. During the quarter ended June 30, 2020, we expensed $3,331,000 associated with stock grants available to MSK and MIT. This includes of future stock grants which will be paid on the anniversary date of the SADA License Agreement in 2021 and 2022. These awards survive the potential termination of the licensing arrangement, unless a breach by the licensors occurs, and can be settled in cash or stock at the determination of the Company. During the quarter ended June 30, 2020, we expensed The SADA License Agreement requires us to pay to MSK and MIT 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, increasing to $60,000 once a patent has been issued, over the royalty term, commencing on the tenth anniversary of the license agreement. These amounts are non-refundable but are creditable against royalty payments otherwise due under the SADA License Agreement. The Company is also obligated to pay MSK and MIT certain clinical, regulatory and sales-based milestone payments under the SADA 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 SADA License Agreement. Total clinical and regulatory milestones potentially due under the SADA License Agreement are $4,730,000 and $18,125,000, respectively. There are also sales-based milestones, totaling $23,750,000, that become due should the Company achieve certain amounts of sales of licensed products. In addition, to the extent we enter into sublicense arrangements, we are obligated to pay to MSK and MIT a percentage of certain payments received from sublicensees of the rights licensed to us by MSK and MIT, which percentage will be based upon the achievement of certain clinical milestones. The Company has not entered into any sublicenses related to the SADA License Agreement. For each of the constructs previously generated by MSK using the SADA technology and sold for the Company by a sublicensee, the Company may pay sales milestones up to Failure by the Company to meet certain conditions under the arrangement could cause the related license to such licensed products to be canceled and could result in termination of the entire arrangement with MSK and MIT. In addition, the Company may terminate the SADA License Agreement with prior written notice. Research and development is inherently uncertain and as described above, should such research and development fail, the SADA License Agreement is cancelable at the Company’s option. The Company will also consider the development risk and each party’s termination rights under the agreement when considering whether any clinical or regulatory based milestone payments, certain of which also contain time-based payment requirements, are probable. The Company records milestones in the period in which the contingent liability is probable and the amount is reasonably estimable. During the three and nine month period ended September 30, 2020, we expensed , respectively, of milestones under the SADA License Agreement. This includes all time-based milestones coming due within We have the following SADA related balances and commitments which include all obligations that have been paid or accrued as of and for the priod ending September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Expense Expense Expense Expense Accrued liabilities Accrued liabilities Accrued liabilities Accrued liabilities Agreements ​ Nine months ended September 2020 ​ Nine months ended September 2020 ​ Nine months ended September 2019 ​ Three months ended September 2020 ​ Three months ended September 2019 ​ Current as of September 2020 ​ Non-current as of September 2020 ​ Current as of September 2019 ​ Non-current as of September 2019 SADA ​ ​ $ 1,995,000 ​ ​ $ 13,307,000 ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ 1,000,000 ​ ​ $ 1,605,000 ​ ​ $ - ​ ​ $ - ​ The below table represents the maximum clinical, regulatory or sales-based miletones as reflected within the agreements, certain of which have been paid in prior periods or are accrued as presented in the table above: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum Agreements ​ Clinical Milestones ​ Regulatory Milestones ​ Sales-based milestones SADA ​ ​ $ 4,730,000 ​ ​ $ 18,125,000 ​ ​ $ 23,750,000 ​ Minimum royalties and certain clinical milestones that become due based upon the passage of time under the SADA Agreement are not recorded as a liability as the Company does not consider such obligations to be probable as of September 30, 2020. ​ ​ 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; 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; and in October 2020 we entered into a SADA sponsored research agreement pursuant to which we agreed to pay MSK to provide research services over a period of three years related to the intellectual property licensed under the SADA License Agreement. For the three months ended September 30, 2020 and 2019, we incurred research and development expenses of $1,050,000 and $1,384,000, respectively, under these agreements. For the nine months ended September 30, 2020 and 2019, we incurred research and development expenses of $3,028,000 and $5,307,000, respectively, under these agreements. Lease Agreements In July 2019, the Company entered a development, manufacturing and supply agreement with SpectronRx in South Bend, Indiana, to secure access to clinical and commercial scale radiolabeling capacity for omburtamab. Under the terms of the agreement, SpectronRx has agreed to establish a manufacturing unit designated for the Company within its existing facilities, at which both clinical and commercial supply of radiolabeled omburtamab can be produced. Since the Company possesses the right to substantially all the economic benefits and directs the use of the production area, the Company accounts for the payments related to the access to the manufacturing space under ASC 842 as an operating lease. The term of the lease is two years from the commencement date of August 31, 2020. Upon the lease commencement date, we recorded $3,617,000 as right of use asset and $2,680,000 as lease liability with the difference of $937,000 being due to prepayment of an initial fee of $500,000 to commence design and construction of the production area and access fees of $437,000 . The company will pay additional access fees of 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. In 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. Total operating lease costs were $330,000 and $174,000 for the three months ended September 30, 2020 and 2019, respectively, and $680,000 and $502,000 for the nine months ended September 30, 2020 and 2019, respectively. For the three months ended September 30, 2020, the operating lease expenses were recorded as $280,000 in research and development expense and $50,000 in general and administrative expense. For the three months ended September 30, 2019, the expenses were recorded as $129,000 in research and development expense and $45,000 in general and administrative expense. For the nine months ended September 30, 2020, the expenses were recorded as $529,000 in research and development expense and $151,000 in general and administrative expense. For the nine months ended September 30, 2019, the expenses were recorded as $367,000 in research and development expense and $135,000 in general and administrative expense. Cash paid for amounts included in the measurement of lease liabilities for the three and nine months ended September 30, 2020 was $201,000 and $594,000, respectively, 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 September 30, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at September 30, 2020 Remainder of 2020 ​ $ 541 Years ending December 31, ​ ​ ​ 2021 ​ ​ 2,168 2022 ​ ​ 1,587 2023 ​ ​ 540 2024 ​ ​ 64 Total lease payments ​ ​ 4,900 Less: Imputed interest ​ ​ (496) Total operating lease liabilities at September 30, 2020 ​ $ 4,404 ​ Maturities of operating leases at December 31, 2019 were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at December 31, 2019 2020 ​ $ 749 2021 ​ ​ 753 2022 ​ ​ 646 2023 ​ ​ 539 2024 ​ ​ 77 Total lease payments ​ ​ 2,764 Less: Imputed interest ​ ​ (534) Total operating lease liabilities at December 31, 2019 ​ $ 2,230 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 September 30, 2020, the weighted average remaining lease term is 2.42 years and the weighted average discount rate used to determine the operating lease liability was 7.6%.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2020
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	NOTE 7—STOCKHOLDERS’ EQUITY Authorized Stock As of September 30, 2020 and December 31, 2019, the Company has authorized a total of 105,500,000 shares, 100,000,000 of which are common stock, par value $0.0001 per share, and 5,500,000 of which are 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 had issued 40,472,435 shares of its common stock as of September 30, 2020 and 39,728,416 shares of its common stock as of December 31, 2019. 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 September 30, 2020 or December 31, 2019. 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 to two non-employee researchers who were involved in the development of technology licensed from MSK in consideration for their prior service. These two researchers were employees of MSK. 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 was fully issued. In 2019 a total of 400,000 shares were issued to one of the physicians, and the remaining 400,000 shares were issued in August 2020, subject to certain conditions. No future shares will be issued under this award. 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 2020, in connection with the SADA License Agreement, we entered into certain stock grant agreements pursuant to which we agreed to issue a total of 213,996 shares to two non-employee researchers who were involved in the development of the SADA technology licensed from MSK and MIT in consideration for their prior service. All 213,996 shares were issued in April 2020 into escrow with 40% of the shares immediately vesting at the time of issuance and the remaining 60% of the shares subject to vesting ratably over the next three years on the anniversary date of the agreement. The shares are subject to forfeiture to the extent the SADA License Agreement is terminated prior to the vesting of the shares. There is no cash settlement feature, and no future service is required for researchers to vest and receive the shares. While the shares vest over time, there is no performance condition for the shares. In April 2020, we recorded an expense within research and development totaling $7,376,000 related to the shares which represents the fair value of the shares on the grant date. In July 2020, pursuant to the stock grant agreements, we also loaned the two researchers a total of $2,610,000 related to their individual tax payments due in conjunction with the stock grants. Each of the loans are evidenced by a three year Secured Promissory Note. The outstanding principal amounts of the loans, together with all accrued interest thereon at the rate of 1% per annum, is due and payable on the maturity date of the loans. The loans are secured by Pledge and Security Agreements, pursuant to which the researchers have pledged the shares as security for repayment of the loans with interest rates that are at market. The loans are recorded at amortized cost, which approximates fair value due to the short-term nature and minimal changes in market interest rates. Issuance of common stock In November 2019, we completed a secondary public offering and issued 5,134,750 shares of our 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.

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2020
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 a four-year period and generally become immediately exercisable upon the occurrence of a change in control, as defined. Stock Option Valuation For the three month periods ended September 30, 2020 and 2019, stock-based compensation for stock option grants were $3,083,000 and $1,324,000, respectively, for options granted to employees and directors. For the three months ended September 30, 2020, the expenses were recorded as $686,000 in research and development expense and $2,397,000 in general and administrative expense. For the three months ended September 30, 2019, the expenses were recorded as $263,000 in research and development expense and $1,061,000 in general and administrative expense. For the nine month periods ended September 30, 2020 and 2019, stock-based compensation for stock option grants were $7,676,000 and $3,124,000, respectively, for options granted to employees and directors. For the nine months ended September 30, 2020, the expenses were recorded as $1,712,000 in research and development expense and $5,964,000 in general and administrative expense. For the nine months ended September 30, 2019, the expenses were recorded as $577,000 in research and development expense and $2,547,000 in general and administrative expense. 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, 2019 4,005,873 ​ $ 10.67 ​ $ 82,944 7.34 Granted 1,196,000 ​ ​ 35.98 ​ ​ ​ ​ ​ Exercised ​ (83,694) ​ ​ 6.99 ​ ​ ​ ​ ​ Forfeited ​ (89,667) ​ ​ 25.00 ​ ​ ​ ​ ​ Outstanding and expected to vest at September 30, 2020 5,028,512 ​ $ 16.50 ​ $ 113,742 ​ 7.26 Exercisable at September 30, 2020 2,900,840 ​ $ 6.81 ​ $ 91,617 ​ 5.97 The weighted average fair value of stock options granted for the three months ended September 30, 2020 was $23.72. There were 155,000 shares stock options granted for the three months ended September 30, 2020. There were no stock options granted during the three months ended September 30, 2019. The weighted average fair value of stock options granted for the nine months ended September 30, 2020 and 2019 was $20.72 and $12.34, 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. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option pricing model. We estimate our expected share price volatility based on the historical volatility of a group of publicly-traded peer companies and we expect to continue to do so until such time as we have adequate historical data regarding the volatility of our own traded share price. The expected term of our stock options has been determined utilizing the “simplified” method for awards as we have 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 we have never paid cash dividends on shares of our common stock and do not expect to pay any cash dividends in the foreseeable future. There were no significant changes to the inputs included in the Black-Scholes option pricing model during the period ended September 30, 2020. ​ As of September 30, 2020, we had $33.0 million of unrecognized compensation expense related to employee stock options that is expected to vest over a period of 2.85 years. As of December 31, 2019, we had $15.9 million of unrecognized compensation expense related to employee stock options that are expected to vest over a period of 2.72 years. Restricted Stock Unit Activity For the three months ended September 30, 2020 and September 30, 2019, stock-based compensation for restricted stock unit grants was $53,000 and $21,000, respectively. For the three months ended September 30, 2020, the expenses were recorded as $48,000 in research and development expense and $5,000 in general and administrative expense. For the three months ended September 30, 2019, the expenses were recorded as $19,000 in research and development expense and $2,000 in general and administrative expense. For the nine months ended September 30, 2020 and September 30, 2019, stock-based compensation for restricted stock unit grants was $123,000 and $56,000, respectively. For the nine months ended September 30, 2020, the expenses were recorded as $112,000 in research and development expense and $11,000 in general and administrative expense. For the nine months ended September 30, 2019, the expenses were recorded as $50,000 in research and development expense and $6,000 in general and administrative expense. The following table summarizes restricted stock units issued and outstanding: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Weighted ​ average ​ ​ ​ ​ ​ average ​ remaining ​ ​ ​ ​ ​ grant ​ vesting ​ ​ ​ Restricted Stock Units ​ price ​ life (years) ​ Outstanding and expected to vest at December 31, 2019 ​ 10,296 ​ $ 23.11 2.05 ​ Granted ​ 21,569 ​ ​ 22.75 ​ Vested ​ (3,429) ​ ​ 23.11 ​ ​ Forfeited ​ (660) ​ ​ 20.76 ​ ​ ​ Outstanding and expected to vest at September 30, 2020 ​ 27,776 ​ $ 23.16 2.40 ​ ​ As of September 30, 2020, we had $524,000 of unrecognized compensation related to employee restricted stock units that are expected to vest over a period of 2.40 years. As of September 30, 2019, we had $183,000 of unrecognized compensation related to employee restricted stock units that are expected to vest over a period of 2.30 years.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2020
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	NOTE 9—RELATED PARTY TRANSACTIONS MSK is a shareholder of the Company. Under the MSK License Agreement, SADA License Agreement, the CD33 License Agreement, and various other supporting agreements with MSK, we have expensed costs in the total amount of $1,050,000 and $1,384,000 in the three months ended September 30, 2020 and 2019, respectively, for milestones, minimum royalties, and research and development costs. We expensed costs in the total amounts of $7,626,000 and $5,307,000 in the nine months ended September 30, 2020 and 2019, respectively, under these agreements with MSK. Please refer to Note 6 – License Agreements and Commitments for additional details on our agreements with MSK. As of September 30, 2020, we had a total of $1,467,000 recorded as accounts payable, $4,709,000 as accrued liabilities, thereby totaling $6,176,000 due to MSK. As of December 31, 2019, we had a total of $188,000 recorded as accounts payable, $3,983,000 as accrued liabilities, thereby totaling $4,171,000 due to MSK.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2020
INCOME TAXES
INCOME TAXES	NOTE 10—INCOME TAXES The Company provided no current and deferred income taxes on net losses of $32.8 million and $23.9 million for the three month periods ended September 30, 2020 and 2019, respectively, and the net losses of $99.4 million and $57.9 million for the nine month periods ended September 30, 2020 and 2019, respectively. 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 September 30, 2020 and December 31, 2019, the Company has determined that there were no uncertain tax positions. The Company’s tax returns for years 2019, 2018, 2017, 2016, and 2015 are open for tax examination by U.S. federal and state, and the Danish tax authorities. The valuation allowance relates primarily to net U.S. deferred tax assets from operating losses, research and development tax credit carryforwards, and acquired intangibles. 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.

OTHER BENEFITS

OTHER BENEFITS	9 Months Ended
	Sep. 30, 2020
OTHER BENEFITS
OTHER BENEFITS	NOTE 11—OTHER BENEFITS The Company has 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 The Company has established a retirement program for employees of the Company’s 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. No contributions from Danish subsidiary were made for three and nine months ended September 30, 2020, and contributions from our Danish subsidiary were immaterial for the three and nine months ended September 30, 2019. 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.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2020
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
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.
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.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. ​ • 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. The following tables present the Company’s fair value hierarchy for its financial instruments, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at September 30, 2020 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ For the quarter ended September 30, 2020, there were no transfers Level 3
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, and the valuation of 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. The full extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations and financial condition, including expenses, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international markets. We have made estimates of the impact of COVID-19 within our financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates.
Segment Information	Segment Information The Company is engaged solely in the discovery and development of novel antibody-based therapeutic products for the treatment of cancer. Accordingly, the Company has determined that it operates in one operating segment.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements – Adopted In August 2018, the FASB issued Accounting Standards Update No. 2018 -13 (“ASU2018-13”), Fair Value Measurement (Topic 820) Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 allows to remove the reasons for transfer between Level 1 and Level 2 assets, and adds the changes in unrealized gains and losses for recurring level 3 fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years with early adoption permitted. The adoption of this standard on January 1, 2020 did not have a material impact on our consolidated financial statements and related disclosures. 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 2018-15 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 adoption of this standard on January 1, 2020 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 all 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 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 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. Please reference Note 6—License Agreement and Commitments for details.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2020
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of financial instruments measured at fair value on recurring basis	The following tables present the Company’s fair value hierarchy for its financial instruments, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at September 30, 2020 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ $ — ​ $ 120,297 ​ $ — ​ $ 120,297 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2020
NET LOSS PER SHARE
Schedule of basic and diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ Nine months ended September 30, ​ ​ 2020 ​ 2019 2020 ​ 2019 ​ ​ ​ (in thousands, except per share amounts) ​ ​ ​ ​ ​ Net loss (numerator) ​ $ (32,832) ​ $ (23,922) ​ $ (99,404) ​ $ (57,892) ​ Weighted-average shares (denominator) ​ 40,187 ​ 34,372 ​ 39,972 ​ 34,254 ​ Basic and diluted net loss per share ​ $ (0.82) ​ $ (0.70) ​ $ (2.49) ​ $ (1.69) ​

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2020
ACCRUED LIABILITIES
Summary of accrued short-term liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 ​ 2019 ​ ​ (in thousands) ​ ​ ​ ​ ​ ​ ​ Accrued licensing, milestone and royalty payments ​ $ 1,334 ​ $ 354 Accrued clinical costs ​ 729 ​ 1,584 Accrued compensation and board fees ​ 3,853 ​ 1,475 Accrued manufacturing costs ​ ​ 1,319 ​ ​ 760 Other ​ 335 ​ 377 Total ​ $ 7,570 ​ $ 4,550

LICENSE AGREEMENTS AND COMMIT_2

LICENSE AGREEMENTS AND COMMITMENTS (Tables)	9 Months Ended
	Sep. 30, 2020
Agreements
Maturities of operating lease liabilities	Maturities of operating lease liabilities at September 30, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at September 30, 2020 Remainder of 2020 ​ $ 541 Years ending December 31, ​ ​ ​ 2021 ​ ​ 2,168 2022 ​ ​ 1,587 2023 ​ ​ 540 2024 ​ ​ 64 Total lease payments ​ ​ 4,900 Less: Imputed interest ​ ​ (496) Total operating lease liabilities at September 30, 2020 ​ $ 4,404 ​ Maturities of operating leases at December 31, 2019 were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at December 31, 2019 2020 ​ $ 749 2021 ​ ​ 753 2022 ​ ​ 646 2023 ​ ​ 539 2024 ​ ​ 77 Total lease payments ​ ​ 2,764 Less: Imputed interest ​ ​ (534) Total operating lease liabilities at December 31, 2019 ​ $ 2,230
MSK, CD33 and MabVax License Agreements
Agreements
Summary of significant license agreements, related commitments and milestone information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Expense Expense Expense Expense Accrued liabilities Accrued liabilities Accrued liabilities Accrued liabilities Agreements ​ Nine months ended September 2020 ​ Nine months ended September 2020 ​ Nine months ended September 2019 ​ Three months ended September 2020 ​ Three months ended September 2019 ​ Current as of September 2020 ​ Non-current as of September 2020 ​ Current as of December 2019 ​ Non-current as of December 2019 MSK ​ ​ $ 80,000 ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ 234,000 ​ ​ $ 1,411,000 ​ ​ $ 254,000 ​ ​ $ 1,471,000 CD33 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 100,000 ​ ​ 450,000 ​ ​ 100,000 ​ ​ 450,000 MabVax ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum Agreements ​ Clinical Milestones ​ Regulatory Milestones ​ Sales-based milestones ​ MSK ​ ​ $ 2,450,000 ​ ​ $ 9,000,000 ​ ​ $ 20,000,000 ​ CD33 ​ ​ 550,000 ​ ​ 500,000 ​ ​ 7,500,000 ​ MabVax ​ ​ 200,000 ​ ​ 1,200,000 ​ ​ — ​
SADA License Agreement
Agreements
Summary of significant license agreements, related commitments and milestone information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Expense Expense Expense Expense Accrued liabilities Accrued liabilities Accrued liabilities Accrued liabilities Agreements ​ Nine months ended September 2020 ​ Nine months ended September 2020 ​ Nine months ended September 2019 ​ Three months ended September 2020 ​ Three months ended September 2019 ​ Current as of September 2020 ​ Non-current as of September 2020 ​ Current as of September 2019 ​ Non-current as of September 2019 SADA ​ ​ $ 1,995,000 ​ ​ $ 13,307,000 ​ ​ $ - ​ ​ $ - ​ ​ $ - ​ ​ $ 1,000,000 ​ ​ $ 1,605,000 ​ ​ $ - ​ ​ $ - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum Agreements ​ Clinical Milestones ​ Regulatory Milestones ​ Sales-based milestones SADA ​ ​ $ 4,730,000 ​ ​ $ 18,125,000 ​ ​ $ 23,750,000

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2020
SHARE-BASED COMPENSATION
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, 2019 4,005,873 ​ $ 10.67 ​ $ 82,944 7.34 Granted 1,196,000 ​ ​ 35.98 ​ ​ ​ ​ ​ Exercised ​ (83,694) ​ ​ 6.99 ​ ​ ​ ​ ​ Forfeited ​ (89,667) ​ ​ 25.00 ​ ​ ​ ​ ​ Outstanding and expected to vest at September 30, 2020 5,028,512 ​ $ 16.50 ​ $ 113,742 ​ 7.26 Exercisable at September 30, 2020 2,900,840 ​ $ 6.81 ​ $ 91,617 ​ 5.97
Schedule of restricted stock units issued and outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Weighted ​ average ​ ​ ​ ​ ​ average ​ remaining ​ ​ ​ ​ ​ grant ​ vesting ​ ​ ​ Restricted Stock Units ​ price ​ life (years) ​ Outstanding and expected to vest at December 31, 2019 ​ 10,296 ​ $ 23.11 2.05 ​ Granted ​ 21,569 ​ ​ 22.75 ​ Vested ​ (3,429) ​ ​ 23.11 ​ ​ Forfeited ​ (660) ​ ​ 20.76 ​ ​ ​ Outstanding and expected to vest at September 30, 2020 ​ 27,776 ​ $ 23.16 2.40 ​

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
BASIS OF PRESENTATION
Accumulated deficit	$ 265,267	$ 165,863
Cash and cash equivalents	$ 131,267	$ 207,136

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Operating Leases (Details) $ in Millions	Sep. 30, 2020USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Residual value guarantees	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair Value Measurement (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair value measurements
Level 1 to Level 2 Transfers	$ 0
Level 2 to Level 1 Transfers	0
Transfers into Level 3	0
Transfers out of Level 3	$ 0
Recurring
Fair value measurements
Cash equivalents		$ 197,879
Recurring | Money market funds
Fair value measurements
Cash equivalents		197,879
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_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment (Details)	9 Months Ended
	Sep. 30, 2020segment
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of operating segments	1

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently issued accounting pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
New accounting pronouncements
Lease liability		$ 4,404	$ 2,230
Operating lease right-of-use assets		$ 5,123	$ 1,989
ASU 2016-02
New accounting pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected	us-gaap:AccountingStandardsUpdate201602CumulativeEffectPeriodOfAdoptionMember
New Accounting Pronouncement or Change in Accounting Principle, Prior Period Not Restated	true
Lease, Practical Expedients, Package	true
ASU 2016-02 | Cumulative Effect, Period of Adoption, 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						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
NET LOSS PER SHARE
Net loss (numerator)	$ (32,832)	$ (40,393)	$ (26,179)	$ (23,922)	$ (18,036)	$ (15,934)	$ (99,404)	$ (57,892)
Weighted-average shares (denominator)	40,187,173			34,371,927			39,971,766	34,253,739
Basic and diluted net loss per share (in dollars per share)	$ (0.82)			$ (0.70)			$ (2.49)	$ (1.69)

NET LOSS PER SHARE - Anti-dilut

NET LOSS PER SHARE - Anti-dilutive securities (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
NET LOSS PER SHARE
Potentially dilutive securities outstanding	5,056,288	4,124,169

ACCRUED LIABILITIES (Details)

ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued short-term liabilities
Accrued licensing, milestone and royalty payments	$ 1,334	$ 354
Accrued clinical costs	729	1,584
Accrued compensation and board fees	3,853	1,475
Accrued manufacturing costs	1,319	760
Other	335	377
Total	$ 7,570	$ 4,550

LICENSE AGREEMENTS AND COMMIT_3

LICENSE AGREEMENTS AND COMMITMENTS - MSK, CD33 and MabVax License Agreement (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)agreement	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)agreement	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Financial statement information
Expense	$ 32,641,000	$ 24,359,000	$ 99,841,000	$ 59,246,000
Accrued liabilities, current	7,570,000		7,570,000		$ 4,550,000
Accrued liabilities, noncurrent	$ 2,466,000		$ 2,466,000		1,921,000
MSK
Agreements
Number of license agreements | agreement	2		2
Msk License Agreement
Financial statement information
Cash paid			$ 80,000
Accrued liabilities, current	$ 234,000		234,000		254,000
Accrued liabilities, noncurrent	1,411,000		1,411,000		1,471,000
Milestones
Maximum Clinical Milestones	2,450,000		2,450,000
Maximum Regulatory Milestones	9,000,000		9,000,000
Maximum Sales-based Milestones	20,000,000		20,000,000
CD33 License Agreement
Financial statement information
Accrued liabilities, current	100,000		100,000		100,000
Accrued liabilities, noncurrent	450,000		450,000		$ 450,000
Milestones
Maximum Clinical Milestones	550,000		550,000
Maximum Regulatory Milestones	500,000		500,000
Maximum Sales-based Milestones	7,500,000		7,500,000
MabVax Agreement
Milestones
Maximum Clinical Milestones	200,000		200,000
Maximum Regulatory Milestones	$ 1,200,000		$ 1,200,000

LICENSE AGREEMENTS AND COMMIT_4

LICENSE AGREEMENTS AND COMMITMENTS - SADA License Agreement (Details) $ in Thousands	Apr. 15, 2020USD ($)individual	Aug. 31, 2020shares	Jul. 31, 2020individual	Apr. 30, 2020USD ($)individualshares	Aug. 31, 2015individual	Sep. 30, 2020USD ($)shares	Jun. 30, 2020USD ($)individualshares	Sep. 30, 2019USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)individualshares	Dec. 31, 2018individualshares	Dec. 31, 2017shares	Dec. 31, 2016shares	Dec. 31, 2015shares
Agreements
Non-cash expense in connection with equity issuance to inventors									$ 7,376
Financial statement information
Expense						$ 32,641		$ 24,359	99,841	$ 59,246
Accrued liabilities, current						7,570			7,570		$ 4,550
Accrued liabilities, noncurrent						$ 2,466			2,466		$ 1,921
Common Stock
Agreements
Issuance of common stock to non-employees (in shares) | shares						400,000	256,896	400,000
Nonemployees | Researchers, Employees of MSK
Agreements
Number of individuals | individual					2						1	2
Nonemployees | Researchers, Employees of MSK | Common Stock
Agreements
Issuance of common stock to non-employees (in shares) | shares		400,000									400,000	544,000	448,000	448,000	560,000
SADA License Agreement
Agreements
Number of employees acquired | individual	0
Upfront payment	$ 1,995
Stock grant expense							$ 3,331
Issuance of common stock to strategic partner							$ 1,331
Issuance of common stock to strategic partner (in shares) | shares							42,900
Accrued stock issuance costs							$ 2,000
Annual minimum royalties payable (non-refundable)	40
Annual minimum royalties payable from tenth anniversary (non-refundable)	60
Maximum sales based milestone payments due for each construct previously generated	$ 60,000
Milestone expenses						$ 0			605
Milestone period	36 months
Financial statement information
Cash paid									1,995
Expense									13,307
Accrued liabilities, current						1,000			1,000
Accrued liabilities, noncurrent						1,605			1,605
Milestones
Maximum Clinical Milestones	$ 4,730					4,730			4,730
Maximum Regulatory Milestones	18,125					18,125			18,125
Maximum Sales-based Milestones	$ 23,750					$ 23,750			$ 23,750
SADA License Agreement | Researchers, Employees of MSK
Agreements
Number of individuals | individual			2
SADA License Agreement | Nonemployees | Researchers, Employees of MSK
Agreements
Non-cash expense in connection with equity issuance to inventors				$ 7,376			$ 7,376
Number of individuals | individual				2			2
SADA License Agreement | Nonemployees | Researchers, Employees of MSK | Common Stock
Agreements
Issuance of common stock to non-employees (in shares) | shares				213,996			213,996

LICENSE AGREEMENTS AND COMMIT_5

LICENSE AGREEMENTS AND COMMITMENTS - Other agreements (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2020	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)agreementindividual	Sep. 30, 2019USD ($)	Dec. 31, 2018
Agreements
Research and development		$ 21,005	$ 19,660	$ 69,686	$ 46,665
Other Agreements
Agreements
Research and development		$ 1,050	$ 1,384	$ 3,028	$ 5,307
CFAs
Agreements
Number of service agreements | agreement				2
CD33-SRA
Agreements
Research service period						2 years
SRA | Subsequent Event
Agreements
Research service period	3 years
Researchers, Employees of MSK | MDSA
Agreements
Number of individuals | individual				5

LICENSE AGREEMENTS AND COMMIT_6

LICENSE AGREEMENTS AND COMMITMENTS - Lease agreements (Details)	Aug. 31, 2020USD ($)	Feb. 28, 2019USD ($)ft²	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Jan. 31, 2018USD ($)
Leases
Operating lease right-of-use assets			$ 5,123,000	$ 1,989,000
Lease liability			$ 4,404,000	$ 2,230,000
Manufacturing facility, Indiana
Leases
Lease term	2 years
Operating lease right-of-use assets	$ 3,617,000
Lease liability	2,680,000
Difference between right of use asset and lease liability recognized	937,000
Initial fee	500,000
Access fee paid	437,000
Amount of additional access fees to be paid in monthly installments	2,796,000
Access fee monthly installment	$ 117,000
Period over which monthly access fee will be paid	2 years
Option to extend	false
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		$ 144,000
Lease payable per month		$ 12,000
Corporate headquarters, New York
Leases
Lease term					5 years
Fixed rent payable per annum					$ 384,000
Lease payable per month					$ 32,000
Office space, Denmark
Leases
Lease term		3 years
Lease payable per month		$ 19,000

LICENSE AGREEMENTS AND COMMIT_7

LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases
Total operating lease costs	$ 330	$ 174	$ 680	$ 502
Cash paid for amounts included in the measurement of lease liabilities	201		594
Research and development expense
Leases
Total operating lease costs	280	129	529	367
General and administrative expense
Leases
Total operating lease costs	$ 50	$ 45	$ 151	$ 135

LICENSE AGREEMENTS AND COMMIT_8

LICENSE AGREEMENTS AND COMMITMENTS - Lease maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Future minimum commitments under all non-cancelable operating leases
Remainder of 2020	$ 541
Next fiscal year	2,168	$ 749
Second fiscal year	1,587	753
Third fiscal year	540	646
Fourth fiscal year	64	539
Fifth fiscal year		77
Total lease payments	4,900	2,764
Less: Imputed interest	(496)	(534)
Total operating lease liabilities at December 31, 2019	$ 4,404	$ 2,230

LICENSE AGREEMENTS AND COMMIT_9

LICENSE AGREEMENTS AND COMMITMENTS - Lease term and discount rate (Details)	Sep. 30, 2020
LICENSE AGREEMENTS AND COMMITMENTS
Weighted average remaining lease term	2 years 5 months 1 day
Weighted average discount rate	7.60%

STOCKHOLDERS' EQUITY - Authoriz

STOCKHOLDERS' EQUITY - Authorized, Common and Preferred Stock (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)Vote$ / sharesshares	Dec. 31, 2019USD ($)$ / 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	$ 0
Common stock, shares issued	40,472,435	39,728,416
Preferred stock, shares issued	0	0

STOCKHOLDERS' EQUITY - Stock gr

STOCKHOLDERS' EQUITY - Stock grant agreements with non-employees, Stock (Details) $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Aug. 31, 2020shares

Jul. 31, 2020USD ($)individual

Apr. 30, 2020USD ($)individualshares

Aug. 31, 2015individualshares

Sep. 30, 2020shares

Jun. 30, 2020USD ($)individualshares

Sep. 30, 2019shares

Sep. 30, 2020USD ($)

Dec. 31, 2019individualshares

Dec. 31, 2018individualitemshares

Dec. 31, 2017shares

Dec. 31, 2016shares

Dec. 31, 2015shares

Share-Based Compensation Awards

Non-cash expense in connection with equity issuance to inventors | $

$ 7,376

Nonemployees | Researchers, Employees of MSK

Share-Based Compensation Awards

Number of individuals | individual

2

1

2

Number of stock grants fully issued | item

1

SADA License Agreement | Researchers, Employees of MSK

Share-Based Compensation Awards

Number of individuals | individual

2

Notes receivable, noncurrent | $

$ 2,610

Notes receivable term

3 years

Notes receivable interest rate (as a percent)

1.00%

SADA License Agreement | Nonemployees | Researchers, Employees of MSK

Share-Based Compensation Awards

Number of individuals | individual

2

2

Non-cash expense in connection with equity issuance to inventors | $

$ 7,376

$ 7,376

SADA License Agreement | Nonemployees | Researchers, Employees of MSK | Tranche one

Share-Based Compensation Awards

Vesting (as a percent)

40.00%

SADA License Agreement | Nonemployees | Researchers, Employees of MSK | Tranche two

Share-Based Compensation Awards

Vesting (as a percent)

60.00%

Vesting period

3 years

Common Stock

Share-Based Compensation Awards

Issuance of common stock to non-employees (in shares)

400,000

256,896

400,000

Common Stock | Nonemployees | Researchers, Employees of MSK

Share-Based Compensation Awards

Shares agreed to be issued

2,800,000

Issuance of common stock to non-employees (in shares)

400,000

400,000

544,000

448,000

448,000

560,000

Common Stock | SADA License Agreement | Nonemployees | Researchers, Employees of MSK

Share-Based Compensation Awards

Shares agreed to be issued

213,996

Issuance of common stock to non-employees (in shares)

213,996

213,996

STOCKHOLDERS' EQUITY - Issuance

STOCKHOLDERS' EQUITY - Issuance of common stock (Details) $ / shares in Units, $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Aug. 31, 2020shares

Jul. 31, 2020individual

Apr. 30, 2020individualshares

Nov. 30, 2019USD ($)$ / sharesshares

Aug. 31, 2015individual

Sep. 30, 2020shares

Jun. 30, 2020individualshares

Mar. 31, 2020shares

Sep. 30, 2019shares

Sep. 30, 2020shares

Dec. 31, 2019individualshares

Dec. 31, 2018individualshares

Dec. 31, 2017shares

Dec. 31, 2016shares

Dec. 31, 2015shares

Issuance of stock

Exercise of stock options (in shares)

83,694

SADA License Agreement

Issuance of stock

Issuance of common stock to strategic partner (in shares)

42,900

Researchers, Employees of MSK | SADA License Agreement

Issuance of stock

Number of individuals | individual

2

Researchers, Employees of MSK | Nonemployees

Issuance of stock

Number of individuals | individual

2

1

2

Researchers, Employees of MSK | Nonemployees | SADA License Agreement

Issuance of stock

Number of individuals | individual

2

2

Secondary Public Offering

Issuance of stock

Payment of offering costs | $

$ 9,100

Common Stock

Issuance of stock

Exercise of stock options (in shares)

57,916

25,778

Restricted stock awards (in shares)

3,429

Issuance of common stock to non-employees (in shares)

400,000

256,896

400,000

Common Stock | Researchers, Employees of MSK | Nonemployees

Issuance of stock

Issuance of common stock to non-employees (in shares)

400,000

400,000

544,000

448,000

448,000

560,000

Common Stock | Researchers, Employees of MSK | Nonemployees | SADA License Agreement

Issuance of stock

Issuance of common stock to non-employees (in shares)

213,996

213,996

Common Stock | Secondary Public Offering

Issuance of stock

Shares issued (in shares)

5,134,750

Share price (in dollars per share) | $ / shares

$ 28

Issuance of shares of common stock, net of issuance costs | $

$ 134,704

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
Share-Based Compensation Awards
Vesting period	4 years

SHARE-BASED COMPENSATION - 2018

SHARE-BASED COMPENSATION - 2018 Plan (Details) - 2018 Plan	9 Months Ended
	Sep. 30, 2020shares
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%
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
Stock options | Participants owning more than 10% of voting power
Share-Based Compensation Awards
Term of award	5 years
Stock options | Participants 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 - Stoc

SHARE-BASED COMPENSATION - Stock option expense (Details) - Stock options - Employees and directors - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-Based Compensation Awards
Stock-based compensation expenses	$ 3,083	$ 1,324	$ 7,676	$ 3,124
Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	686	263	1,712	577
General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 2,397	$ 1,061	$ 5,964	$ 2,547

SHARE-BASED COMPENSATION - St_2

SHARE-BASED COMPENSATION - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Options
Outstanding at beginning of period (in shares)			4,005,873
Granted (in shares)	155,000	0	1,196,000
Exercised (in shares)			(83,694)
Forfeited, shares (in shares)			(89,667)
Outstanding at end of period (in shares)	5,028,512		5,028,512		4,005,873
Exercisable at end of period (in shares)	2,900,840		2,900,840
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)			$ 10.67
Granted (in dollars per share)			35.98
Exercised (in dollars per share)			6.99
Forfeited (in dollars per share)			25
Outstanding at end of period (in dollars per share)	$ 16.50		16.50		$ 10.67
Exercisable at end of period (in dollars per share)	$ 6.81		$ 6.81
Aggregate intrinsic value and Weighted average remaining contractual life (years)
Outstanding (in dollars)	$ 113,742		$ 113,742		$ 82,944
Exercisable (in dollars)	$ 91,617		$ 91,617
Outstanding (in years)			7 years 3 months 3 days		7 years 4 months 2 days
Exercisable (in years)			5 years 11 months 19 days
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 23.72		$ 20.72	$ 12.34

SHARE-BASED COMPENSATION - St_3

SHARE-BASED COMPENSATION - Stock option unrecognized compensation (Details) - Stock options - Employees - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Unrecognized compensation related to employee stock options
Unrecognized compensation	$ 33	$ 15.9
Expected vesting period	2 years 10 months 6 days	2 years 8 months 19 days

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock Unit Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Share-Based Compensation Awards
Stock-based compensation expenses	$ 53	$ 21	$ 123	$ 56
Restricted stock units issued and outstanding
Outstanding and expected to vest at beginning of period (in shares)			10,296
Granted (in shares)			21,569
Vested (in shares)			(3,429)
Forfeited (in shares)			(660)
Outstanding and expected to vest at end of period (in shares)	27,776		27,776		10,296
Weighted average grant price
Weighted average grant price, Outstanding and expected to vest, Beginning of period (in dollars per share)			$ 23.11
Weighted average grant price, Grants (in dollars per share)			22.75
Weighted average grant price, Vested (in dollars per share)			23.11
Weighted average grant price, Forfeited (in dollars per share)			20.76
Weighted average grant price, Outstanding and expected to vest, End of period (in dollars per share)	$ 23.16		$ 23.16		$ 23.11
Weighted average remaining vesting life			2 years 4 months 24 days	2 years 3 months 18 days	2 years 18 days
Unrecognized compensation	$ 524	183	$ 524	$ 183
Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	48	19	112	50
General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 5	$ 2	$ 11	$ 6

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - MSK - MSK License Agreement, CD33 License Agreement, CTA, CFAs, SRA and MDSA - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related party transactions
Expensed costs	$ 1,050	$ 1,384	$ 7,626	$ 5,307
Due to related parties, Accounts payable	1,467		1,467		$ 188
Due to related parties, Accrued liabilities	4,709		4,709		3,983
Due to related parties	$ 6,176		$ 6,176		$ 4,171

INCOME TAXES - Expense (Details

INCOME TAXES - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Domestic and foreign loss before income taxes:
Losses before taxes	$ (32,800)	$ (23,900)	$ (99,400)	$ (57,900)
Income tax expense
Current income taxes	0	0
Deferred income taxes	$ 0	$ 0

INCOME TAXES - Uncertain tax po

INCOME TAXES - Uncertain tax positions (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
INCOME TAXES
Uncertain tax position	$ 0	$ 0

OTHER BENEFITS (Details)

OTHER BENEFITS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employer matching contribution to defined contribution plan (as a percent)	0.00%	0.00%	0.00%	0.00%
Danish Subsidiary
Employer matching contribution to defined contribution plan (as a percent)	0.00%		0.00%
Costs for employee health insurance benefits	$ 0		$ 0