Y-mAbs Therapeutics (YMAB) 10-Q 10 Aug 23 2023 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Aug. 03, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
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	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		43,620,192
Entity Central Index Key	0001722964
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
CURRENT ASSETS
Cash and cash equivalents	$ 87,909	$ 105,762
Accounts receivable, net	19,118	12,531
Inventories	5,187	6,702
Other current assets	3,570	5,452
Total current assets	115,784	130,447
Property and equipment, net	375	604
Operating lease right-of-use assets	1,178	1,739
Intangible assets, net	2,809	2,986
Other assets	12,250	5,680
TOTAL ASSETS	132,396	141,456
LIABILITIES
Accounts payable	7,252	14,175
Accrued liabilities	16,152	13,241
Operating lease liabilities, current portion	829	868
Total current liabilities	24,233	28,284
Accrued milestone and royalty payments	2,250	2,250
Operating lease liabilities, long-term portion	416	899
Other liabilities	816	802
TOTAL LIABILITIES	27,715	32,235
Commitments and contingencies (Note 9)
STOCKHOLDERS' EQUITY
Preferred stock, $0.0001 par value, 5,500,000 shares authorized and none issued at June 30, 2023 and December 31, 2022
Common stock, $0.0001 par value, 100,000,000 shares authorized at June 30, 2023 and December 31, 2022; 43,620,192 and 43,670,109 shares issued at June 30, 2023 and December 31, 2022, respectively	4	4
Additional paid-in capital	552,369	543,929
Accumulated other comprehensive income	1,043	1,331
Accumulated deficit	(448,735)	(436,043)
TOTAL STOCKHOLDERS' EQUITY	104,681	109,221
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 132,396	$ 141,456

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
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	43,620,192	43,670,109

Consolidated Statements of Net

Consolidated Statements of Net Loss and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
REVENUES
Total revenues	$ 20,751	$ 10,797	$ 41,002	$ 21,283
OPERATING COSTS AND EXPENSES
Cost of goods sold	4,649	1,140	6,732	2,972
License royalties		100		100
Research and development	12,055	26,420	25,473	49,332
Selling, general, and administrative	11,270	23,082	23,521	36,520
Total operating costs and expenses	27,974	50,742	55,726	88,924
Loss from operations	(7,223)	(39,945)	(14,724)	(67,641)
OTHER INCOME / (LOSS), NET
Interest and other income/(loss)	1,100	(1,186)	2,211	(1,558)
LOSS BEFORE INCOME TAXES	(6,123)	(41,131)	(12,513)	(69,199)
Provision for income taxes	179		179
NET LOSS	(6,302)	(41,131)	(12,692)	(69,199)
Other comprehensive income/(loss)
Foreign currency translation	18	1,422	(288)	1,733
COMPREHENSIVE LOSS	$ (6,284)	$ (39,709)	$ (12,980)	$ (67,466)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.14)	$ (0.94)	$ (0.29)	$ (1.58)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.14)	$ (0.94)	$ (0.29)	$ (1.58)
Weighted average common shares outstanding, basic (in shares)	43,663,112	43,718,748	43,667,385	43,713,967
Weighted average common shares outstanding, diluted (in shares)	43,663,112	43,718,748	43,667,385	43,713,967
Product
REVENUES
Total revenues	$ 20,751	$ 9,797	$ 41,002	$ 20,283
License
REVENUES
Total revenues		$ 1,000		$ 1,000

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, 2021	$ 4	$ 519,206	$ 1,371	$ (340,475)	$ 180,106
Balance at the beginning of period (in shares) at Dec. 31, 2021	43,694,716
Increase (Decrease) in Stockholders' Equity
Exercise of stock options		32			32
Exercise of stock options (in shares)	16,000
Stock-based compensation expense		5,091			5,091
Stock-based compensation expense (in shares)	7,449
Foreign currency translation			311		311
Net loss				(28,068)	(28,068)
Balance at the end of period at Mar. 31, 2022	$ 4	524,329	1,682	(368,543)	157,472
Balance at the end of period (in shares) at Mar. 31, 2022	43,718,165
Balance at the beginning of period at Dec. 31, 2021	$ 4	519,206	1,371	(340,475)	180,106
Balance at the beginning of period (in shares) at Dec. 31, 2021	43,694,716
Increase (Decrease) in Stockholders' Equity
Net loss					(69,199)
Balance at the end of period at Jun. 30, 2022	$ 4	537,962	3,104	(409,674)	131,396
Balance at the end of period (in shares) at Jun. 30, 2022	43,720,038
Balance at the beginning of period at Mar. 31, 2022	$ 4	524,329	1,682	(368,543)	157,472
Balance at the beginning of period (in shares) at Mar. 31, 2022	43,718,165
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		13,633			13,633
Stock-based compensation expense (in shares)	1,873
Foreign currency translation			1,422		1,422
Net loss				(41,131)	(41,131)
Balance at the end of period at Jun. 30, 2022	$ 4	537,962	3,104	(409,674)	131,396
Balance at the end of period (in shares) at Jun. 30, 2022	43,720,038
Balance at the beginning of period at Dec. 31, 2022	$ 4	543,929	1,331	(436,043)	109,221
Balance at the beginning of period (in shares) at Dec. 31, 2022	43,670,109
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		5,304			5,304
Stock-based compensation expense (in shares)	7,658
Foreign currency translation			(306)		(306)
Net loss				(6,390)	(6,390)
Balance at the end of period at Mar. 31, 2023	$ 4	549,233	1,025	(442,433)	107,829
Balance at the end of period (in shares) at Mar. 31, 2023	43,677,767
Balance at the beginning of period at Dec. 31, 2022	$ 4	543,929	1,331	(436,043)	109,221
Balance at the beginning of period (in shares) at Dec. 31, 2022	43,670,109
Increase (Decrease) in Stockholders' Equity
Net loss					(12,692)
Balance at the end of period at Jun. 30, 2023	$ 4	552,369	1,043	(448,735)	104,681
Balance at the end of period (in shares) at Jun. 30, 2023	43,620,192
Balance at the beginning of period at Mar. 31, 2023	$ 4	549,233	1,025	(442,433)	107,829
Balance at the beginning of period (in shares) at Mar. 31, 2023	43,677,767
Increase (Decrease) in Stockholders' Equity
Retirement of treasury shares - refer to Note 10		(480)			(480)
Retirement of treasury shares - refer to Note 10 (in shares)	(58,763)
Stock-based compensation expense		3,616			3,616
Stock-based compensation expense (in shares)	1,188
Foreign currency translation			18		18
Net loss				(6,302)	(6,302)
Balance at the end of period at Jun. 30, 2023	$ 4	$ 552,369	$ 1,043	$ (448,735)	$ 104,681
Balance at the end of period (in shares) at Jun. 30, 2023	43,620,192

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (12,692)	$ (69,199)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	406	383
Stock-based compensation	8,920	18,724
Foreign currency transactions	(774)	1,733
Changes in assets and liabilities:
Accounts receivable, net	(6,587)	504
Inventories	1,515	(1,282)
Other current assets	1,402	1,220
Other assets	(6,570)	(2,579)
Accounts payable	(6,149)	(2,261)
Accrued liabilities and other	2,671	4,732
NET CASH USED IN OPERATING ACTIVITIES	(17,858)	(48,025)
CASH FLOWS FROM INVESTING ACTIVITIES
NET CASH PROVIDED BY INVESTING ACTIVITIES
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercised stock options		32
NET CASH PROVIDED BY FINANCING ACTIVITIES		32
Effect of exchange rates on cash and cash equivalents	5	94
NET DECREASE IN CASH AND CASH EQUIVALENTS	(17,853)	(47,899)
Cash and cash equivalents at the beginning of period	105,762	181,564
Cash and cash equivalents at the end of period	87,909	133,665
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Acquisition of treasury shares upon repayment of secured promissory note - refer to Note 10	$ 480
Intangible assets acquisition in accrued milestones and royalty payments		$ 1,500

ORGANIZATION AND DESCRIPTION OF

ORGANIZATION AND DESCRIPTION OF BUSINESS	6 Months Ended
	Jun. 30, 2023
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 commercial stage biopharmaceutical company focused on the development and commercialization of novel, antibody-based therapeutic products for the treatment of cancer. We are leveraging our proprietary antibody platforms and deep expertise in the field of antibodies to develop a broad portfolio of innovative medicines. The Company is headquartered in New York and was incorporated on April 30, 2015 under the laws of the State of Delaware.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2023
BASIS OF PRESENTATION
BASIS OF PRESENTATION	NOTE 2—BASIS OF PRESENTATION The Company has incurred losses in almost all quarters 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 the FDA approval in the United States and regulatory approval in other jurisdictions; marketing or sales capability or experience; uncertainty in getting adequate payor 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 pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance reporting capabilities. The Company’s drug candidates are in various stages of development. DANYELZA (naxitamab-gqgk) received accelerated approval by the FDA in November 2020, but there can be no assurance that the Company’s other research and development efforts 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 and commercialization 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 consolidated 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 $448,735,000 as of June 30, 2023, and $436,043,000 as of December 31, 2022. Through June 30, 2023, the Company has funded its operations primarily through proceeds from sales of shares of its common stock, including its initial public offering in September 2018 and its subsequent public offerings in November 2019 and February 2021, as well as additional funding from the sales of DANYELZA and from the sale of the Company’s Priority Review Voucher (“PRV”) obtained upon FDA approval of DANYELZA. As of June 30, 2023, the Company had cash and cash equivalents of $87,909,000, and as of December 31, 2022, the Company had cash and cash equivalents of $105,762,000. As of the issuance date of the consolidated financial statements for the second quarter ended June 30, 2023, the Company expects that its cash and cash equivalents at June 30, 2023, will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next 12 months, irrespective of whether any additional 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. These financing sources are in addition to successful commercialization of DANYELZA and our product candidates, for which the Company may obtain regulatory approval and marketing authorization. The Company’s commercialization strategy may include working with a collaborator or distributor. Sufficient funds may not be available to the Company on attractive terms or at all when needed from equity or debt financing. If 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 the Company’s liquidity position which may include significantly reducing the current rate of spending through delaying or 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 subsidiaries 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 the instructions to Form 10-Q. Accordingly, these consolidated financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim consolidated 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 six-month periods ended June 30, 2023, are not necessarily indicative of the results that may be expected for the year ending December 31, 2023, any other interim periods, or any future year or period. The December 31, 2022, 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 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, 2022.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 3—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The Company’s significant accounting policies are detailed in its Annual Report on Form 10-K for the year ended December 31, 2022. 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 a loss 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. The Company maintains cash balances in excess of insured limits. The Company monitors the financial performance, credit ratings and liquidity of the money market fund to timely assess and respond to any changes in the asset values of the fund. The Company does not anticipate any loss with respect to such cash balances. Accounts Receivable, Net The Company’s accounts receivable, net balance consists of amounts due from sales of our approved product, DANYELZA. Receivables from product sales are recorded net of allowances which generally include chargebacks, doubtful accounts, rebates, returns, and discounts. The allowance is based primarily on assessment of specific identifiable customer accounts considered at risk or uncollectible, as well as an analysis of current receivables aging and expected future write-offs. The Company has not historically experienced any significant credit losses. All customer accounts are actively managed, and no losses are currently expected. Concentration of Credit Risk The Company’s product sales are made through arrangements primarily with three national specialty distributors in the United States of America. As of June 30, 2023, the accounts receivable balances from such distributors totaled 71% of the Company’s outstanding accounts receivable. The remainder of the Company’s accounts receivable as of June 30, 2023 represented balances from international distribution partners. The Company has contractual payment terms with each of its customers and the Company monitors their financial performance, historical payment terms and credit worthiness to timely assess and respond to any changes in their credit profile. Inventories The Company values its inventories at the lower of cost or net realizable value on a first-in, first-out basis. The Company’s inventory cost includes amounts related to materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. Raw and intermediate materials that may be utilized for both commercial and clinical programs are identical and given the alternative future use such amounts are initially classified as inventory. Amounts in inventory associated with clinical development programs are charged to research and development expense when the product enters the research and development process and can no longer be used for commercial purposes and, therefore, does not have an alternative future use. The Company capitalizes inventory costs related to products to be sold in the ordinary course of business. The Company makes a determination of capitalizing inventory costs for a product based on, among other factors, status of regulatory approval, information regarding safety, efficacy and expectations relating to commercial sales and recoverability of costs. For DANYELZA, the Company commenced capitalization of inventory at the receipt of FDA approval. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment occurs. Such impairment charges, should they occur, are recorded within cost of goods sold. The determination of whether inventory costs will be realizable requires estimates by management. The Company had inventory write-downs totaling $456,000 in the three and six months ended June 30, 2023, which were recorded in cost of goods sold on the Consolidated Statements of Net Loss and Comprehensive Loss. 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 cash equivalents, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at June 30, 2023 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 Total ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965 Total ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965 ​ During the three and six months ended June 30, 2023, there were no transfers Level 3 Operating Lease Right-of-Use Assets and Operating Lease Liabilities 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. The Company currently elects the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, the Company 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. The Company also elects 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 9—LICENSE AGREEMENTS AND COMMITMENTS 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, net product revenues, 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. Revenue Recognition Product revenue, net To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The company only applies the five-step model to arrangements that meet the definition of a contract with a customer under ASC 606, including when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Under the practical expedient permitted under Topic 606, the Company expenses incremental costs of obtaining a contract as and when incurred if the expected amortization period of the assets is one year or less. If there are multiple distinct performance obligations, we allocate the transaction price to each distinct performance obligation based on its relative standalone selling price. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, the Company combines that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The standalone selling price is generally determined based on the prices charged to customers. The Company recognizes revenue from sales of DANYELZA at a point in time when its customer is deemed to have obtained control of the product, which generally occurs upon receipt at the end-user hospital. The amount of revenue the Company recognizes from sales of DANYELZA varies due to rebates, chargebacks and discounts provided under governmental and other programs, distribution-related fees and other sales-related deductions. In order to determine those deductions, the Company estimates, utilizing the expected value method, the amount of revenue that it will ultimately be entitled to. This estimate is based upon contracts with customers and government agencies, statutorily-defined discounts applicable to government-funded programs, estimated payor mix, and other relevant factors. Calculating these amounts involves estimates and judgments, and the Company reviews these estimates quarterly. If actual results vary from its original estimates, the Company will adjust these estimates quarterly, which would affect net product revenue and earnings in the period such variances occur. ● Rebates and chargebacks The Company contracts with United States governmental agencies to ensure that DANYELZA will be eligible for coverage under the various programs administered by the agencies. The Company estimates the rebates and chargebacks to be provided and deducts these estimated amounts from its gross product revenues. These reserves are recorded in the same period the revenue is recognized, resulting in a reduction of product revenue and the establishment of accrued liabilities for the rebates and a reduction of accounts receivable for the chargebacks. The Company develops estimates for rebates and chargebacks based upon (i) the Company’s contracts with these agencies, (ii) the government-mandated discounts applicable to government-funded programs, and (iii) information obtained from hospitals and third-party consultants regarding the payor mix. The Company’s liability for these rebates and chargebacks mainly consists of claims for which invoices have not yet been received and paid. The Company does not maintain material levels of inventory in the wholesale or retail channel. ● Discounts and distribution-related fees The Company provides invoice discounts on DANYELZA sales to its distributors for prompt payment and fees for distribution services and invoice discounts reduce the original accounts receivable balances. The payment terms for sales to distributors generally include a 2% discount for prompt payment or fees for distribution services which are based on contractual rates agreed with the respective distributors. Based on historical data and experiences with the distributors, the Company expects its distributors to earn these discounts and fees and deduct the full amount of these discounts and fees from its gross product revenue at the time such revenues are recognized. ● Returns The Company offers its customers limited product return rights for damaged, defective, or expiring products. The Company estimates returns on sales of DANYELZA mainly based on information provided to the Company from the hospitals and distributors. The return reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and establishment of an accrued liability. ​ In December 2022, the Company announced a distribution agreement with WEP Clinical Ltd., or WEP, in connection with an early access program for DANYELZA in Europe. There are no regulatory-based or sales-based milestone payments or royalty arrangements under this distribution agreement. The Company recognizes revenue when the customer obtains control of the product upon delivery to WEP. The Company invoices WEP based on the terms of the distribution agreement, where a portion is billed upon shipment of product and the unbilled portion is billed at a later date based on terms of the distribution agreement. The Company has an unconditional right to the unbilled portion of the receivable and the Company estimates that the receivable will be collected within one year and therefore has recorded the balance at June 30, 2023, within accounts receivable on the Consolidated Balance Sheets. License revenue In December 2020, the Company entered into a development and commercialization arrangement with SciClone International Pharmaceuticals Ltd., or SciClone, for certain indications of DANYELZA and omburtamab for Greater China, including Mainland China, Taiwan, Hong Kong and Macau. Based on the terms of the agreement, the Company may receive regulatory-based milestone payments up to $40,000,000 and sales-based milestone payments up to $60,000,000 and is entitled to royalties based upon the net sales generated by SciClone related to the product indications in the territory. In December 2022, the Company received a regulatory-based milestone payment of $15,000,000 for the conditional approval of DANYELZA in China. The Company determined that the achievement of the remaining regulatory-based milestones within the agreement are constrained as they are contingent upon regulatory approvals which are not within its control and therefore not deemed probable. The Company expects that the sales-based milestones and royalty payments will be recognized when the milestone is achieved or the related sales occur. The Company re-evaluates the transaction price each quarter and as uncertain events are resolved or other changes in circumstances occur, it assesses whether this resolves the constraint and it is appropriate to recognize revenue. In November 2020, we entered into an exclusive license and distribution agreement for DANYELZA and omburtamab with Takeda Israel, a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited covering the State of Israel, West Bank and Gaza Strip. Based on the terms of the arrangement, the Company may receive regulatory-based milestone payments up to $750,000, of which $250,000 has already been recognized, and sales-based milestone payments up to $500,000 and is entitled to royalties based upon the net sales generated by Takeda related to the product in the territory. The Company expects that the remaining regulatory-based and sales-based milestones will be recognized when the milestone is achieved, or the related sales occur. In December 2020, the Company entered into a distribution agreement for DANYELZA and omburtamab with Swixx BioPharma AG for the Eastern European territories Bosnia & Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Russia, Serbia, Slovakia and Slovenia. There are no regulatory-based or sales-based milestone payments or royalty arrangements under this distribution agreement. In May 2021, the Company entered into an exclusive distribution agreement with Adium Pharma S.A. (“Adium”) for Adium to be the exclusive distributor in Latin America of the Company’s antibodies omburtamab, if approved, and DANYELZA. Under the terms of the agreement, the Company may receive regulatory-based milestone payments up to an aggregate of $3,000,000. The Company received the first of these milestone payments totaling $1,000,000 in April 2022 upon the submission of the updated FDA Biologics License Application (“BLA”) dossier for DANYELZA. In addition, the Company is entitled to royalties based upon DANYELZA net sales generated by Adium in Latin America. The Company determined that the achievement of the remaining regulatory-based milestones within the agreement are constrained as they are contingent upon regulatory approvals which are not within the Company’s control and therefore not deemed probable. The agreement with Adium does not contain a regulatory-based milestone related to the Brazilian Health Regulatory Agency’s approval for marketing authorization, which was granted during the three months ended June 30, 2023. The Company expects that the sales-based milestones and royalty payments will be recognized when and if the milestones are achieved or the related sales occur. The Company reevaluates the transaction price each quarter and as uncertain events are resolved or other changes in circumstances occur, the Company assesses whether this resolves the constraint and it is appropriate to recognize revenue. The Company did not recognize license revenue in the three and six months ended June 30, 2023. Segment Information The Company is engaged solely in the discovery, development, distribution and commercialization 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 From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, and are adopted by the Company as of the specific effective date. The Company adopted ASU 2022-04, ASU 2022-02, ASU 2022-01 and ASU 2021-08 effective January 1, 2023, and the adoption of these new standards did not have a material impact on the Company’s consolidated financial statements or disclosures. The Company has evaluated accounting pronouncements recently issued but not yet adopted and believes that these pronouncements do not apply to the Company’s operations and therefore will not have a material impact on the Company’s consolidated financial statements or disclosures.

PRODUCT REVENUE, NET

PRODUCT REVENUE, NET	6 Months Ended
	Jun. 30, 2023
PRODUCT REVENUE, NET
PRODUCT REVENUE, NET	NOTE 4—PRODUCT REVENUE, NET The Company’s product revenue, net was generated from sales of DANYELZA and totaled $20,751,000 and $9,797,000 for the three months ended June 30, 2023 and 2022, respectively. The geographic breakout for the product revenue, net between the United States and other countries for the three months ended June 30, 2023, were $15,851,000 and $4,900,000, respectively. The geographic breakout for the product revenue, net between in the United States and other countries for the three months ended June 30, 2022, was $9,021,000 and $776,000, respectively. The Company’s product revenue, net from other countries for the three months ended June 30, 2023, included $3,535,000 of product revenue and related royalties for the commercial launch inventory stocking order from the Company’s distribution partner, SciClone, which launched commercial sales in China during the three months ended June 30, 2023. The product revenue, net from SciClone reflected an initial inventory stocking and the Company does not anticipate recurring product revenue, net at this level each quarter. The Company’s product revenue, net was generated from sales of DANYELZA and totaled $41,002,000 and $20,283,000 for the six months ended June 30, 2023 and 2022, respectively. The geographic breakout for the product revenue, net between the United States and other countries for the six months ended June 30, 2023, were $32,685,000 and $8,317,000, respectively. The geographic breakout for the product revenue, net between the United States and other countries for the six months ended June 30, 2022 was $18,453,000 and $1,830,000, respectively. The Company’s product revenue, net from other countries for the six months ended June 30, 2023, included $3,535,000 of product revenue and related royalties for the commercial launch inventory stocking order from the Company’s distribution partner, SciClone, which launched commercial sales in China during the six months ended June 30, 2023. The Company’s revenue from other countries for the six months ended June 30, 2023, also includes $2,516,000 of product revenue from the Company’s distribution partner, WEP, in connection with the Company’s early access program for DANYELZA in Europe. Please refer to below for further discussion regarding the WEP distribution agreement. The product revenue, net from WEP and SciClone in the six months ended June 30, 2023, reflected initial inventory stockings and the Company does not anticipate recurring product revenue, net from each distribution partner at these levels each quarter. Revenue from product sales is recorded net of applicable provisions for rebates, chargebacks, discounts, distribution-related fees and other sales-related deductions. Accruals for chargebacks and discounts are recorded as a direct reduction to accounts receivable. Accruals for rebates, distribution-related fees without contractual right of offset and other sales-related deductions are recorded within accrued liabilities. As of June 30, 2023, the Company had recorded accounts receivable allowances of approximately $476,000 and accrued liabilities of approximately $4,739,000 related to product sales during the six months ended June 30, 2023. As of December 31, 2022, the Company had recorded accounts receivable allowances of approximately $508,000 and accrued liabilities of $2,474,000 related to product sales. An analysis of the change in reserves for discounts and allowances is summarized as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contractual ​ ​ ​ ​ ​ ​ ​ Allowances and ​ ​ ​ ​ ​ ​ ​ Discounts ​ Government Rebates Returns ​ Total ​ (in thousands) Balance December 31, 2022 $ 33 ​ $ 2,905 ​ $ 44 ​ $ 2,982 Current provisions relating to sales in current year ​ 120 ​ ​ 5,897 ​ ​ 242 ​ ​ 6,259 Payments/credits relating to sales in current year ​ (113) ​ ​ (3,693) ​ ​ (220) ​ ​ (4,026) Balance June 30, 2023 $ 40 ​ $ 5,109 ​ $ 66 ​ $ 5,215 ​ The vast majority of the Company’s product sales were in the United States with additional sales in China, Europe and Israel through sublicenses and distribution agreements. The Company had product sales to certain customers that accounted for more than 10% of total product revenue, net, for the three and six months ended June 30, 2023, and June 30, 2022. McKesson, SciClone, AmerisourceBergen and Cardinal Health accounted for 46%, 20%, 18% and 12% respectively, of the Company’s product revenue, net, for the three months ended June 30, 2023. McKesson, AmerisourceBergen and Cardinal Health accounted for 71%, 10% and 11%, respectively, of the Company’s product revenue, net, for the three months ended June 30, 2022. McKesson, AmerisourceBergen, Cardinal Health and SciClone accounted for 44%, 23%, 12% and 12%, respectively, of the Company’s product revenue, net, for the six months ended June 30, 2023. McKesson, AmerisourceBergen and Cardinal Health accounted for 64%, 17% and 11%, respectively, of the Company’s product revenue, net, for the six months ended June 30, 2022. The Company recognized royalty revenue from their distribution partners of $2,620,000 and $738,000 in the three months ended June 30, 2023 and 2022, respectively, and $3,387,000 and $1,354,000 in the six months ended June 30, 2023 and 2022, respectively. Under the Company’s distribution agreement with WEP, the Company is entitled to receive all payments based on the net product sales and pays WEP a service fee in exchange for its services, whereby the service fee represents a percentage of gross selling price and is included within product revenue, net on the Consolidated Statements of Net Loss and Comprehensive Loss. There was no product revenue, net from WEP in the three months ended June 30, 2023. The product revenue recognized for the six months ended June 30, 2023, was $2,516,000. There was no product revenue, net from WEP in the three and six months ended June 30, 2022. As of June 30, 2023, the Company has recorded on its Consolidated Balance Sheets accounts receivable of approximately $2,307,000, and accrued liabilities, for allowances, of $133,000 related to product sales to the distribution partner during the six months ended June 30, 2023.

NET LOSS PER SHARE

NET LOSS PER SHARE	6 Months Ended
	Jun. 30, 2023
NET LOSS PER SHARE
NET LOSS PER SHARE	NOTE 5—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 (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ 2023 ​ 2022 2023 ​ 2022 ​ ​ ​ (in thousands, except per share amounts) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss (numerator) ​ $ (6,302) ​ $ (41,131) ​ $ (12,692) ​ $ (69,199) ​ Weighted-average shares (denominator), basic and diluted ​ 43,663 ​ 43,719 ​ 43,667 ​ 43,714 ​ Basic and diluted net loss per share ​ $ (0.14) ​ $ (0.94) ​ $ (0.29) ​ $ (1.58) ​ ​ Potentially dilutive securities excluded from the computation of diluted earnings per share relate to stock options and unvested restricted stock units outstanding, which totaled 8,975,495 shares as of June 30, 2023 and 6,972,558 shares as of June 30, 2022.

INVENTORIES

INVENTORIES	6 Months Ended
	Jun. 30, 2023
INVENTORIES
INVENTORIES	NOTE 6—INVENTORIES Inventories consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2023 ​ December 31, 2022 ​ ​ ​ ​ ​ ​ Work In Progress ​ $ 13,849 ​ $ 11,317 Finished Goods ​ ​ 2,998 ​ ​ 666 Total Inventories ​ $ 16,847 ​ $ 11,983 ​ ​ ​ ​ ​ ​ ​ ​ Inventories are classified on the Consolidated Balance Sheets in each respective period (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2023 ​ December 31, 2022 CURRENT ASSETS ​ ​ ​ ​ ​ ​ Inventories ​ $ 5,187 ​ $ 6,702 Total recorded in Current Assets ​ ​ 5,187 ​ ​ 6,702 ​ ​ ​ ​ ​ ​ ​ NONCURRENT ASSETS ​ ​ ​ ​ ​ ​ Other assets ​ ​ 11,660 ​ ​ 5,281 Total recorded in Noncurrent Assets ​ ​ 11,660 ​ ​ 5,281 Total Inventories ​ $ 16,847 ​ $ 11,983 ​ As of June 30, 2023 and December 31, 2022, the Company has classified $11,660,000 and $5,281,000, respectively, of work in progress inventories as noncurrent assets based on its current demand schedule and expectation that such inventory will be utilized in excess of one year from the balance sheet date. Changes in noncurrent assets are reflected on the Consolidated Statements of Cash Flows within the caption of other assets.

INTANGIBLE ASSETS, NET

INTANGIBLE ASSETS, NET	6 Months Ended
	Jun. 30, 2023
INTANGIBLE ASSETS, NET
INTANGIBLE ASSETS, NET	NOTE 7—INTANGIBLE ASSETS, NET The Company’s intangible assets, net as of June 30, 2023 totaled $2,809,000, which were net of $491,000 of accumulated amortization, and related to capitalized milestone payments made following FDA and other regulatory approvals and commercialization of DANYELZA. The Company’s intangible assets, net as of December 31, 2022 totaled $2,986,000, which were net of $314,000 of accumulated amortization, and related to capitalized milestone payments made following FDA and other regulatory approvals and commercialization of DANYELZA. Intangible assets are amortized on a straight-line basis based on a 10-year useful life of the assets. Annual amortization expense is expected to be $355,000 each year for the five period 202 2027

ACCRUED LIABILITIES

ACCRUED LIABILITIES	6 Months Ended
	Jun. 30, 2023
ACCRUED LIABILITIES
ACCRUED LIABILITIES	NOTE 8—ACCRUED LIABILITIES Accrued liabilities as of June 30, 2023 and December 31, 2022, are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, ​ 2023 ​ 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued licensing, milestone and royalty payments ​ $ 2,777 ​ $ 4,002 Accrued clinical costs ​ 1,005 ​ 932 Accrued compensation and board fees ​ 2,510 ​ 2,445 Accrued manufacturing costs ​ ​ 4,671 ​ ​ 2,977 Accrued sales reserves ​ ​ 4,739 ​ ​ 2,474 Other ​ 450 ​ 411 Total ​ $ 16,152 ​ $ 13,241 ​

LICENSE AGREEMENTS AND COMMITME

LICENSE AGREEMENTS AND COMMITMENTS	6 Months Ended
	Jun. 30, 2023
LICENSE AGREEMENTS AND COMMITMENTS
LICENSE AGREEMENTS AND COMMITMENTS	NOTE 9—LICENSE AGREEMENTS AND COMMITMENTS The Company has entered into three license agreements and certain other agreements with Memorial Sloan Kettering Cancer Center (“MSK”). The license agreements are the MSK License Agreement, dated August 20, 2015, between the Company and MSK (the “MSK License”), the License Agreement, dated November 13, 2017, between the Company and MSK (the “CD33 License Agreement”), and the License Agreement, dated April 15, 2020, between the Company, MSK and Massachusetts Institute of Technology (“MIT”) (the “SADA License Agreement”). Through the Settlement and Assumption and Assignment of the MSK License and Y-mAbs Sublicense Agreement, dated December 2, 2019, among MabVax Therapeutics Holdings, Inc. and MabVax Therapeutics, Inc., (together “MabVax”), the Company and MSK (the “SAAA”), 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. In addition, the Company entered the SADA License Agreement with MSK and Massachusetts Institute of Technology (“MIT”) in 2020. 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 payments are contingent milestone and royalty payments, as disclosed in the table below. Amounts disclosed in NOTE 8—ACCRUED LIABILITIES In the past, the Company had defined MSK as a related-party under the Company’s related-party policy. During the three months ended June 30, 2023, the Company updated the related-party policy to remove MSK as a related-party as MSK does not participate on the Company’s Board of Directors, does not have a significant ownership in the Company and MSK is not in a position to exert decision making power. The Company has entered into several agreements with MSK, which include the MSK License Agreement, the SADA License Agreement, the CD33 License Agreement, and the MabVax Agreement, all as noted above. The Company’s material license agreements are detailed in N ote 9—License Agreements and Commitments MSK License Agreement The MSK License relates to intellectual property for DANYELZA and requires the Company to pay to MSK mid to high single-digit royalties based on annual net sales of licensed products or the performance of licensed services by the Company and the Company’s affiliates and sublicensees. The Company is required to pay annual minimum royalties of $80,000 over the royalty term, which amounts are non-refundable but are creditable against royalty payments otherwise due thereunder. The Company is also obligated to pay to MSK certain clinical, regulatory and sales-based milestone payments under the MSK License, which payments become due upon achievement of the related clinical, regulatory or sales-based milestones. As product candidates developed using technology from the MSK License progress through clinical development, and potential regulatory approval and commercialization, certain of these clinical and regulatory milestone payments become due at the earlier of completion of the related milestone activity or the date indicated in the MSK License. In addition to any milestone payments, to the extent the Company enters into sublicense arrangements, the Company is required to pay to MSK a percentage of certain payments that the Company receives from sublicensees of the rights licensed to the Company by MSK under the MSK License, which percentage will be based upon the achievement of certain clinical milestones. The Company has entered into sublicenses and distribution agreements related to DANYELZA and omburtamab under the MSK License with Takeda Israel, Swixx BioPharma AG and SciClone in 2020, with Adium in 2021, and with WEP in 2022. The MSK License will expire, on a country-by-country basis, and on a licensed-product by licensed-product or licensed-service by licensed-service basis, on the later of (i) the expiration of the last to expire of the patents and patent applications covering such licensed product or service in such country, (ii) the expiration of any market exclusivity period granted by a regulatory authority for such licensed product or service in such country, or (iii) 15 years from the first commercial sale of such licensed product or service in such country. MSK may terminate the MSK License upon prior written notice in the event of the Company’s uncured material breach, or upon prior written notice if such breach is of a payment obligation. MSK may also terminate the MSK License upon written notice in the event of the Company’s bankruptcy or insolvency or the Company’s conviction of a felony relating to the licensed products, or if the Company challenges the validity or enforceability of any licensed patent right. In addition, the Company has the right to terminate the MSK License in its entirety at will upon prior written notice to MSK, but if the Company has commenced the commercialization of licensed products and/or licensed services the Company can only terminate at will if the Company ceases all development and commercialization of such licensed products and/or licensed services. The Company’s failure to meet certain conditions under the MSK License could cause the license related to such licensed product to be canceled and could result in termination of the MSK License by MSK. SADA License Agreement Pursuant to the SADA License Agreement, the Company was granted 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”). At the time of entering into the arrangement, the Company assessed the licensing and other rights acquired and given the lack of outputs upon acquisition and that no employees were acquired, among other factors, the Company has concluded that the licensing rights represented an asset acquisition. The Company 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. The SADA License Agreement requires the Company 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 the Company and its affiliates and sublicensees. The Company is 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. As product candidates developed using technology from the SADA License Agreement progress through clinical development, and potential regulatory approval and commercialization, certain of these 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. In addition to any milestone payments, to the extent the Company enters into sublicense arrangements, it is obligated to pay to MSK and MIT a percentage of certain payments received from sublicensees of the rights licensed to it 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 $60,000,000, in total, based on the achievement of various levels of cumulative net sales made by the sublicensee. 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. Summary of Significant License Agreements and Related Commitments The Company has the following significant license agreements and related commitments which include all obligations that have been paid or accrued for the three and six months ended June 30, 2023 and 2022, and as of June 30, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Cash paid Expense Expense Expense Expense ​ Accrued Accrued Accrued Accrued ​ ​ Six ​ Six ​ Three ​ Six ​ Three ​ Six ​ liabilities liabilities liabilities liabilities ​ ​ months ​ months ​ months ​ months ​ months ​ months ​ Current ​ Non-current ​ Current ​ Non-current ​ ​ ​ ended ​ ended ​ ended ​ ended ​ ended ​ ended ​ as of ​ as of ​ as of ​ as of ​ ​ ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ December 31, ​ December 31, ​ Agreements ​ 2023 ​ 2022 ​ 2023 ​ 2023 ​ 2022 ​ 2022 ​ 2023 ​ 2023 ​ 2022 ​ 2022 ​ MSK ​ $ 3,245 ​ $ 1,263 ​ $ 1,479 ​ $ 2,702 ​ $ 1,083 ​ $ 1,760 ​ $ 2,777 ​ $ 1,950 ​ $ 3,397 ​ $ 1,950 ​ CD33 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 300 ​ ​ — ​ ​ 300 ​ MabVax ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ SADA ​ ​ 605 ​ ​ 1,000 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 605 ​ ​ — ​ ​ Minimum royalties and certain clinical and regulatory milestones that become due based upon the passage of time under the CD33 License Agreement, the SADA Agreement and the MabVax/MSK License Agreement are excluded from the above table as the Company does not consider such obligations to be probable as of June 30, 2023. The below table represents the maximum clinical, regulatory or sales-based milestones as reflected within the agreements, certain of which have been paid in prior periods or are accrued as presented in the table above (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum ​ ​ Clinical ​ Regulatory ​ Sales-based Agreements ​ Milestones ​ Milestones ​ Milestones MSK ​ $ 2,450 ​ $ 9,000 ​ $ 20,000 CD33 ​ ​ 550 ​ ​ 500 ​ ​ 7,500 MabVax ​ ​ 200 ​ ​ 1,200 ​ ​ — SADA ​ ​ 4,730 ​ ​ 18,125 ​ ​ 23,750 ​ Research and development is inherently uncertain and should such research and development fail the MSK License Agreement, the CD33 License Agreement, the SADA License Agreement and the MabVax Agreement as well as the MabVax/Y-mAbs Sublicense are cancelable at the Company’s option. The Company will also consider the development risk and each party’s termination rights under the respective 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. The Company did not recognize any expense related to milestones under the SADA License Agreement during the three and six months ended June 30, 2023 and 2022, as no additional milestones were determined to be probable. The Company had $605,000, in accrued liabilities as of December 31, 2022, which was accrued upon entry into the arrangement in 2020. The Company made a payment of $605,000 in the quarter ended June 30, 2023 related to achievement of the milestone for dosing the first patient in the Phase 1 trial of GD2-SADA in April 2023, and did not have any accrued liabilities as of June 30, 2023 related to milestones under SADA License Agreement. During the second half of 2023, the Company anticipates having the necessary data for a further assessment of clinical progress to determine whether any other milestones under the agreement are deemed probable. The Company did not consider any other milestones under the SADA License Agreement to be probable as of June 30, 2023 and December 31, 2022. 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 had established a manufacturing unit designated for the Company within its existing facilities, at which both clinical and commercial supply of radiolabeled omburtamab could be produced. Since the Company possessed the right to substantially all the economic benefits and directs the use of the production area, the Company accounted for the payments related to the access to the manufacturing space under ASC 842 as an operating lease. The original term of the lease was two years from the commencement date of August 31, 2020, which was subsequently extended to December 2022. The Company entered into an additional one-month extension that terminated in January 2023 for a de minimis cost. In February 2019, the Company entered into a lease agreement in connection with its 4,548 square feet laboratory in New Jersey. In December 2019, the Company expanded the space with an additional 235 square feet. The original term of the lease was three years from the date the Company occupied the premises, with an option to extend for an additional two years which was to expire in January 2024, which the Company exercised and had included in the determination of the related lease liability. In July 2023, the Company entered into a lease amendment to extend the term to February 2025. Fixed rent payable under the lease is approximately $177,000 per annum and is payable in equal monthly installments of approximately $15,000 per month. In January 2018, the Company entered into a lease agreement in connection with its corporate headquarters in New York. The term of the lease was six years from the date the Company began to occupy the premises and the lease was to expire in April 2024. 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. In February 2018, the Company entered into a lease agreement for certain office space in Denmark, which has been amended several times. The lease was renewed on November 1, 2021 with a four-year term that expires in November 2025. The lease is payable in monthly installments of approximately $41,000, which is recognized on a straight-line basis. In January 2023, the Company notified the landlord of its intention to reduce the leased premise as a result of the Company’s strategic restructuring, which was approved by the Company’s Board of Directors on January 4, 2023. The lease modification resulted in an immaterial charge in the six months ended June 30, 2023. Total operating lease costs were $220,000 and $701,000 for the three months ended June 30, 2023 and 2022, respectively. Total operating lease costs were $560,000 and $1,406,000 for the six months ended June 30, 2023 and 2022, respectively. The decrease in operating lease costs in three and six months ended June 30, 2023 compared to the same periods in 2022 was due to the SpectronRx lease which we terminated in January 2023 as discussed above. For the three months ended June 30, 2023, the operating lease expenses were recorded as $163,000 in research and development expense and $57,000 in selling, general and administrative expense. For the three months ended June 30, 2022, the expenses were recorded as $641,000 in research and development expense and $60,000 in selling, general and administrative expense. For the six months ended June 30, 2023, the expenses were recorded as $446,000 in research and development expense and $114,000 in selling, general and administrative expense. For the six months ended June 30, 2022, the expenses were recorded as $1,279,000 in research and development expense and $127,000 in selling, general and administrative expense. Cash paid for amounts included in the measurement of lease liabilities for the three and six months ended June 30, 2023, was $266,000 and $525,000, respectively, and cash paid for amounts included in the measurement of lease liabilities for the three and six months ended June 30, 2022, was $601,000 and $1,208,000, respectively. These payments were included in net cash used in operating activities in the Company’s Consolidated Statements of Cash Flows. Maturities of operating lease liabilities at June 30, 2023, were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at June 30, 2023 Remainder of 2023 ​ $ 531 Years ending December 31, ​ ​ ​ 2024 ​ ​ 477 2025 ​ ​ 369 Total lease payments ​ ​ 1,377 Less: Imputed interest ​ ​ (132) Total operating lease liabilities at June 30, 2023 ​ $ 1,245 ​ Maturities of operating leases liabilities as of December 31, 2022, were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases Years ending December 31, at December 31, 2022 2023 ​ $ 997 2024 ​ ​ 490 2025 ​ ​ 419 Total lease payments ​ ​ 1,906 Less: Imputed interest ​ ​ (139) Total operating lease liabilities at December 31, 2022 ​ $ 1,767 ​ 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 June 30, 2023, the weighted average remaining lease term is 1.98 years and the weighted average discount rate used to determine the operating lease liability was 8.4%. As of December 31, 2022, the weighted average remaining lease term was 2.36 years and the weighted average discount rate used to determine the operating lease liability was 8.3%. Former Chief Executive Officer Contractual Severance Related Benefits On April 27, 2022, the Company announced certain executive management changes. Effective April 22, 2022, Dr. Claus Juan Møller San Pedro stepped down from his positions as Chief Executive Officer and as a member of the Company’s Board of Directors. There were no disagreements with the Company expressed by Dr. Møller on any matters relating the Company’s operations, policies or practices. Dr. Møller’s contractual severance related benefits provided for cash compensation of $1,589,000, which included salary and certain benefits continuation. All of the cash compensation had been paid as of June 30, 2023. Also, under terms of the equity award agreement, Dr. Møller’s outstanding stock option awards will continue to vest as scheduled and become exercisable when vested. This resulted in a non-cash share-based compensation charge of $9,286,000 in the three and six months ended June 30, 2022, as there is no longer a service condition related to such awards. The total charge of $10,875,000 related to executive management change was recorded in selling, general and administrative expenses during the three and the six months ended June 30, 2022. There was no financial impact in the three and six months ended June 30, 2023. Legal Matters Donoghue vs. Y-mAbs Therapeutics, Inc., and Gad The Company has been named a nominal defendant in a lawsuit filed in the U.S. District Court, Southern District of New York, on August 25, 2021, by one of the Company’s stockholders, Deborah Donoghue (Case No. 1:21-cv-07182). The suit names the Company’s President, Interim Chief Executive Officer and Head of Business Development and Strategy, and member of the Company’s board of directors, Mr. Thomas Gad as an additional defendant, and it seeks to compel Mr. Gad to disgorge alleged short swing profits stemming from a certain transaction involving the Company’s common stock undertaken by Mr. Gad on March 10, 2021 together with appropriate interest and costs of the lawsuit. On December 17, 2021, Mr. Gad filed a Motion to Dismiss the lawsuit. On August 8, 2022, the Court denied Mr. Gad’s Motion to Dismiss the lawsuit. The parties have completed documentary discovery and depositions and the action is currently stayed through August 22, 2023. The Company is of the opinion that the claim is without merit and intends to maintain this position in the proceedings. In addition, the Company has been informed by Mr. Gad that he also believes the claim is without merit, that he has strong defenses against such claim and that he intends to vigorously defend the action. The Company has assessed the proceedings and does not believe that it is probable that a gain or a liability will be realized by the Company. As a result, the Company did not record any loss or gain contingencies for this matter. In re Y-mAbs Therapeutics, Inc. Securities Litigation On January 18, 2023, a putative class-action lawsuit was filed against the Company and certain of its current and former officers for alleged violations of the U.S. federal securities laws in the United States District Court, Southern District of New York (Case No.: 1:23-cv-00431). The amended complaint filed on May 23, 2023, asserts claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, on behalf of a proposed class consisting of those who acquired the Company’s common stock between October 6, 2020 and October 28, 2022. The amended complaint alleges that there were material misrepresentations and/or omissions regarding the FDA’s consideration of the Company’s BLA for omburtamab for the treatment of pediatric patients with CNS/leptomeningeal metastasis from neuroblastoma firstly submitted in 2020 and resubmitted in 2022. The amended complaint seeks unspecified damages, and costs and expenses, including attorneys’ fees. On April 4, 2023, the Court appointed a lead plaintiff for the putative class. On July 11, 2023, the defendants filed a motion to dismiss the amended complaint. The plaintiff has until August 29, 2023 to file his opposition to the motion to dismiss. The Company believes that these claims are without merit and intends to vigorously defend against these claims. The Company has not established a liability for this claim as of June 30, 2023 as the Company does not consider the loss on the claim to be probable. Hazelton vs. Y-mAbs Therapeutics Inc., and Gad, et al. The Company has been named a nominal defendant in a lawsuit filed in the Court of Chancery of the State of Delaware, on February 8, 2023, by a purported stockholder, Jeffrey Hazelton (Case No. 2023-0147-LWW). The amended complaint filed on May 12, 2023, purports to bring claims on behalf of the Company against current and former members of the Company’s board of directors for allegedly awarding themselves excessive compensation for fiscal years 2020 and 2021. The amended complaint seeks, among other things, recovery of alleged excessive compensation, an order directing the Company to undertake certain corporate governance reforms, and an award of costs and expenses, including attorneys’ fees. On June 22, 2023, the defendants filed a motion to dismiss the amended complaint. The plaintiff has until August 11, 2023, to file his opposition to the motion to dismiss. The Company is of the opinion that the claims are without merit and intends to maintain this position in the proceedings. The Company has not established a liability for this claim as of June 30, 2023 as the Company does not consider the loss on the claim to be probable.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	6 Months Ended
	Jun. 30, 2023
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	NOTE 10—STOCKHOLDERS’ EQUITY Authorized Stock As of June 30, 2023 and December 31, 2022, the Company had 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 43,620,192 shares of its common stock as of June 30, 2023, and 43,670,109 shares of its common stock as of December 31, 2022. 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 June 30, 2023 or December 31, 2022. Stock Grant Agreements with Non-Employees In April 2020, in connection with the SADA License Agreement, the Company entered into two stock grant agreements pursuant to which it agreed to issue a total of 213,996 shares to two non-employee researchers who were involved in the development of the SADA-BiDE (2-step Self-Assembly and DisAssembly-Bispecific DOTA-Engaging antibody system) Pre-targeted Radioimmunotherapy Platform in consideration for their respective 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 remaining 20% of the award vested in April 2023 resulting in all 213,996 shares being vested as of June 30, 2023. There is no cash settlement feature, and no future service is required for the non-employee researchers to vest and receive the shares. In April 2020, the Company recognized $7,376,000, the fair value of the issued shares on the grant date, within research and development expense. There is no future expense related to these awards. In July 2020, pursuant to the stock grant agreements, the Company 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 were evidenced by a Secured Promissory Note, which had respective maturity dates in April 2023 and June 2023. The outstanding principal amount of each loan, together with all accrued interest thereon at the rate of 1% per annum, was due and payable on the respective maturity dates of the loans. The loans were secured by Pledge and Security Agreements, pursuant to which the researchers pledged the shares as security for repayment of the loans. In July 2022, one of the researchers repaid their loan, which had a maturity date in April 2023, and accrued interest, which resulted in a de minimis loss compared to the amortized cost of the loan, in exchange for 57,887 shares that remained pledged as part of its security. Upon receipt, the Company recorded treasury shares at an acquisition cost of $963,000, based on the share price on the settlement date. The Company subsequently cancelled the acquired treasury shares resulting in a reduction of outstanding common stock and a reduction of additional paid-in-capital totaling $963,000. During the fourth quarter of 2022, the Company concluded that the other loan receivable, with a maturity date of June 2023, was impaired, which resulted in a $1,051,000 charge for the year ended December 31, 2022. In June 2023, the other researcher repaid his loan, which resulted in a de minimis gain compared to the book value of the loan, which included the impact of the previous impairment charge. The loan was repaid in exchange for 58,763 shares that remained pledged as part of its security. Upon receipt, the Company recorded treasury shares at an acquisition cost of $480,000, based on the closing price of the Company’s common stock on the settlement date. The Company subsequently cancelled the acquired treasury shares, which resulted in a reduction of outstanding common stock and a reduction of additional paid-in-capital totaling $480,000.

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2023
SHARE-BASED COMPENSATION
SHARE-BASED COMPENSATION	NOTE 11—STOCK-BASED COMPENSATION 2015 Equity Incentive Plan The Company’s board of directors and stockholders approved and adopted the Amended and Restated 2015 Equity Incentive Plan (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 the Company’s 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 the Company’s employees, directors and consultants and its parent and subsidiary corporations’ employees and consultants. A total of 4,500,000 shares of the Company’s 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. 2018 Equity Incentive Plan The Company’s board of directors and stockholders approved and adopted the 2018 Equity Incentive Plan (the “2018 Plan”) in connection with the Company’s initial public offering in September 2018. However, options outstanding under the 2015 Plan continue to be governed by the 2015 Plan. The 2018 Plan provides for the grant of incentive stock options, within the meaning of Section 422 of the Code (the Internal Revenue Code), to the Company’s 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 the Company’s employees, directors and consultants and the Company’s parent and subsidiary corporations’ employees and consultants. A total of 5,500,000 shares of the Company’s common stock, inclusive of the awards previously granted under the 2015 Equity Incentive Plan were initially 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 through 2029, equal to 4% of the outstanding shares of common stock as of the last day of the Company’s immediately preceding fiscal year or by a lesser amount determined by the board of directors. The exercise price of options granted under the plans must at least be equal to the fair market value of the Company’s 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 the Company’s 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 between one and four years and generally become immediately exercisable upon the occurrence of a change in control, as defined in the Plan Agreement. Stock Options During the three-month periods ended June 30, 2023 and 2022, stock-based compensation for stock option grants were $3,447,000 and $13,549,000, respectively, for options granted to employees and directors. The expense for the three months ended June 30, 2022, includes $9,286,000 related to the departure of the former Chief Executive Officer as described in  NOTE 9—LICENSE AGREEMENTS AND COMMITMENTS During the six-month periods ended June 30, 2023 and 2022, stock-based compensation for stock option grants were $8,564,000 and $18,566,000, respectively, for options granted to employees and directors. The expense for the six months ended June 30, 2023, was inclusive of an acceleration of stock-based compensation of $1,706,000, as described further in NOTE 14— RESTRUCTURING CHARGE NOTE 9—LICENSE AGREEMENTS AND COMMITMENTS recorded as $3,454,000 in research and development expense and $5,110,000 in selling, general, and administrative expense. For the six months ended June 30, 2022, the expenses were recorded as $3,781,000 in research and development expense and $14,785,000 in selling, 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, 2022 7,079,767 ​ $ 21.27 ​ $ 3,112 ​ 6.45 Granted 1,744,900 ​ ​ 5.00 ​ ​ ​ ​ ​ Exercised ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Forfeited ​ (214,006) ​ ​ 10.93 ​ ​ ​ ​ ​ Outstanding and expected to vest at June 30, 2023 8,610,661 ​ $ 18.23 ​ $ 9,387 ​ 6.61 Exercisable at June 30, 2023 5,556,135 ​ ​ 20.12 ​ ​ 6,384 ​ 5.35 ​ The weighted average fair value of stock options granted for the three months ended June 30, 2023 and 2022 was $5.50 and $6.28, respectively. There were 208,200 and 425,000 stock options granted for the three months ended June 30, 2023 and 2022, respectively. The weighted average fair value of stock options granted for the six months ended June 30, 2023 and 2022 was $3.65 and $6.28, respectively. There were 1,744,900 and 425,000 stock options granted for the six months ended June 30, 2023 and 2022, respectively. There were 1,105,500 options granted in the six months ended June 30, 2023 under the Company’s retention program, which were granted to the continuing employees that were not subject to the Company’s strategic restructuring plan. All of the options granted in the three months ended June 30, 2023, have a maximum contractual term of ten years. During the three months ended June 30, 2023, 83,700 options were granted to non-executive directors, which will vest on the first first 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. The Company’s public trading commenced in September 2018, and, as a result, there is only limited available historical volatility experience. Therefore, the Company estimates expected share price volatility based on a combination of the historical volatility of a group of publicly traded peer companies and the historical volatility of the Y-mAbs share price, and the Company expects to continue to do so until such time as the Company has adequate historical data regarding the volatility of its own traded share price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards as it has limited historical data to support the expected term assumption. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is based on the fact that the Company has never paid cash dividends on shares of its common stock and the Company does 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 June 30, 2023. As of June 30, 2023, the Company had $20,523,000 of unrecognized compensation expense related to employee stock options that are expected to vest over a period of 2.74 years. Restricted Stock Unit Activity For the three months ended June 30, 2023 and 2022, stock-based compensation for restricted stock unit grants was $169,000 and $84,000, respectively. During the three months ended June 30, 2023, the expenses were recorded as $98,000 in research and development expense and $71,000 in selling, general, and administrative expense. During the three months ended June 30, 2022, the expenses were recorded as $74,000 in research and development expense and $10,000 in selling, general, and administrative expense. For the six months ended June 30, 2023 and 2022, stock-based compensation for restricted stock unit grants was $356,000 and $158,000, respectively. For the six months ended June 30, 2023, the expenses were recorded as $224,000 in research and development expense and $132,000 in selling, general, and administrative expense. For the six months ended June 30, 2022, the expenses were recorded as $142,000 in research and development expense and $16,000 in selling, 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, 2022 ​ 33,355 ​ $ 17.77 1.77 ​ Granted ​ 380,635 ​ ​ 4.81 ​ Vested ​ (8,846) ​ ​ 15.89 ​ ​ Forfeited ​ (40,310) ​ ​ 9.55 ​ ​ ​ Outstanding and expected to vest at June 30, 2023 ​ 364,834 ​ $ 5.20 2.46 ​ ​ The table above includes 380,635 restricted stock units granted in the six months ended June 30, 2023, under the Company’s retention program, which were granted to the continuing employees that were not subject to the Company’s strategic restructuring plan. As of June 30, 2023, the Company had $1,596,000 of unrecognized compensation related to employee restricted stock units that are expected to vest over a period of 2.46 years.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2023
INCOME TAXES
INCOME TAXES	NOTE 12—INCOME TAXES During the three months ended June 30, 2023 and 2022, the Company experienced pre-tax net losses of $6,123,000 and $41,131,000 . The Company's current income tax provision was t have a current income tax provision during the three months ended June 30, 2022. There was During the six months ended June 30, 2023 and 2022, the Company experienced pre-tax net losses of $12,513,000 and $69,199,000 . The Company's current income tax provision was t have a current income tax provision during the six months ended June 30, 2022. There was The Company’s tax returns for the years 2021, 2020, 2019, 2018, and 2017 are open for tax examination by U.S. federal and state, and the Danish tax authorities. During 2022, the review of the Company’s transfer pricing policies by the Danish Tax Authorities for tax years 2016 through 2020 was completed resulting in the release of the corresponding reserve. The release did not have a material impact on the Company’s income tax accounts. 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	6 Months Ended
	Jun. 30, 2023
OTHER BENEFITS
OTHER BENEFITS	NOTE 13—OTHER BENEFITS The Company has adopted a defined contribution 401(k) savings plan (the “401(k) plan”) covering all U.S. employees. Participants may elect to defer a percentage of their pretax or after-tax compensation to the 401(k) plan, subject to defined limitations. The plan allows for a discretionary match by the Company. The Company made no matching contributions to the plan during the three and six months ended June 30, 2023 and 2022. The Company has established a retirement program for employees of its 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. The Danish subsidiary made no contributions during the three and six months ended June 30, 2023 and 2022. 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.

RESTRUCTURING CHARGE

RESTRUCTURING CHARGE	6 Months Ended
	Jun. 30, 2023
RESTRUCTURING CHARGE
RESTRUCTURING CHARGE	NOTE 14 —RESTRUCTURING CHARGE On January 4, 2023, following Board approval, the Company announced a strategic restructuring plan designed to extend its cash resources and prioritize resources on the commercialization and potential label extension of DANYELZA and on the development of the SADA technology platform. The Company completed the restructuring in May 2023, which resulted in an approximately 35% reduction to its workforce. Affected employees were offered separation benefits, including severance and outplacement services along with temporary healthcare coverage assistance. As a result, during the six months ended June 30, 2023, the Company recognized restructuring expenses of $4,482,000, based on the currency rate for the period. For the six months ended June 30, 2023, the Company recorded $3,346,000 and $1,136,000, respectively, within research and development and selling, general, and administrative, on the Consolidated Statements of Net Loss and Comprehensive Loss. The restructuring expenses primarily related to severance termination benefits of $2,776,000 and acceleration of stock-based compensation of $1,706,000. Regarding the severance termination benefits of $2,776,000, a total of $1,671,000 was paid in cash during the three months ended March 31, 2023, and the remaining $1,105,000 was paid in cash during the three months ended June 30, 2023. The Company recognized acceleration of stock-based compensation of $1,706,000 in the six months ended June 30, 2023 as there is no longer a service condition related to such awards.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
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 a loss 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. The Company maintains cash balances in excess of insured limits. The Company monitors the financial performance, credit ratings and liquidity of the money market fund to timely assess and respond to any changes in the asset values of the fund. The Company does not anticipate any loss with respect to such cash balances.
Accounts Receivable, Net	Accounts Receivable, Net The Company’s accounts receivable, net balance consists of amounts due from sales of our approved product, DANYELZA. Receivables from product sales are recorded net of allowances which generally include chargebacks, doubtful accounts, rebates, returns, and discounts. The allowance is based primarily on assessment of specific identifiable customer accounts considered at risk or uncollectible, as well as an analysis of current receivables aging and expected future write-offs. The Company has not historically experienced any significant credit losses. All customer accounts are actively managed, and no losses are currently expected.
Concentration of Credit Risk	Concentration of Credit Risk The Company’s product sales are made through arrangements primarily with three national specialty distributors in the United States of America. As of June 30, 2023, the accounts receivable balances from such distributors totaled 71% of the Company’s outstanding accounts receivable. The remainder of the Company’s accounts receivable as of June 30, 2023 represented balances from international distribution partners. The Company has contractual payment terms with each of its customers and the Company monitors their financial performance, historical payment terms and credit worthiness to timely assess and respond to any changes in their credit profile.
Inventories	Inventories The Company values its inventories at the lower of cost or net realizable value on a first-in, first-out basis. The Company’s inventory cost includes amounts related to materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. Raw and intermediate materials that may be utilized for both commercial and clinical programs are identical and given the alternative future use such amounts are initially classified as inventory. Amounts in inventory associated with clinical development programs are charged to research and development expense when the product enters the research and development process and can no longer be used for commercial purposes and, therefore, does not have an alternative future use. The Company capitalizes inventory costs related to products to be sold in the ordinary course of business. The Company makes a determination of capitalizing inventory costs for a product based on, among other factors, status of regulatory approval, information regarding safety, efficacy and expectations relating to commercial sales and recoverability of costs. For DANYELZA, the Company commenced capitalization of inventory at the receipt of FDA approval. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment occurs. Such impairment charges, should they occur, are recorded within cost of goods sold. The determination of whether inventory costs will be realizable requires estimates by management. The Company had inventory write-downs totaling $456,000 in the three and six months ended June 30, 2023, which were recorded in cost of goods sold on the Consolidated Statements of Net Loss and Comprehensive Loss.
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 cash equivalents, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at June 30, 2023 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 Total ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965 Total ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965 ​ During the three and six months ended June 30, 2023, there were no transfers Level 3
Operating Lease Right-of-Use Assets and Operating Lease Liabilities	Operating Lease Right-of-Use Assets and Operating Lease Liabilities 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. The Company currently elects the short-term lease recognition exemption for all leases that qualify. This means, for those leases that qualify, the Company 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. The Company also elects 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 9—LICENSE AGREEMENTS AND COMMITMENTS
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, net product revenues, 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.
Revenue Recognition	Revenue Recognition Product revenue, net To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The company only applies the five-step model to arrangements that meet the definition of a contract with a customer under ASC 606, including when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Under the practical expedient permitted under Topic 606, the Company expenses incremental costs of obtaining a contract as and when incurred if the expected amortization period of the assets is one year or less. If there are multiple distinct performance obligations, we allocate the transaction price to each distinct performance obligation based on its relative standalone selling price. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, the Company combines that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The standalone selling price is generally determined based on the prices charged to customers. The Company recognizes revenue from sales of DANYELZA at a point in time when its customer is deemed to have obtained control of the product, which generally occurs upon receipt at the end-user hospital. The amount of revenue the Company recognizes from sales of DANYELZA varies due to rebates, chargebacks and discounts provided under governmental and other programs, distribution-related fees and other sales-related deductions. In order to determine those deductions, the Company estimates, utilizing the expected value method, the amount of revenue that it will ultimately be entitled to. This estimate is based upon contracts with customers and government agencies, statutorily-defined discounts applicable to government-funded programs, estimated payor mix, and other relevant factors. Calculating these amounts involves estimates and judgments, and the Company reviews these estimates quarterly. If actual results vary from its original estimates, the Company will adjust these estimates quarterly, which would affect net product revenue and earnings in the period such variances occur. ● Rebates and chargebacks The Company contracts with United States governmental agencies to ensure that DANYELZA will be eligible for coverage under the various programs administered by the agencies. The Company estimates the rebates and chargebacks to be provided and deducts these estimated amounts from its gross product revenues. These reserves are recorded in the same period the revenue is recognized, resulting in a reduction of product revenue and the establishment of accrued liabilities for the rebates and a reduction of accounts receivable for the chargebacks. The Company develops estimates for rebates and chargebacks based upon (i) the Company’s contracts with these agencies, (ii) the government-mandated discounts applicable to government-funded programs, and (iii) information obtained from hospitals and third-party consultants regarding the payor mix. The Company’s liability for these rebates and chargebacks mainly consists of claims for which invoices have not yet been received and paid. The Company does not maintain material levels of inventory in the wholesale or retail channel. ● Discounts and distribution-related fees The Company provides invoice discounts on DANYELZA sales to its distributors for prompt payment and fees for distribution services and invoice discounts reduce the original accounts receivable balances. The payment terms for sales to distributors generally include a 2% discount for prompt payment or fees for distribution services which are based on contractual rates agreed with the respective distributors. Based on historical data and experiences with the distributors, the Company expects its distributors to earn these discounts and fees and deduct the full amount of these discounts and fees from its gross product revenue at the time such revenues are recognized. ● Returns The Company offers its customers limited product return rights for damaged, defective, or expiring products. The Company estimates returns on sales of DANYELZA mainly based on information provided to the Company from the hospitals and distributors. The return reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and establishment of an accrued liability. ​ In December 2022, the Company announced a distribution agreement with WEP Clinical Ltd., or WEP, in connection with an early access program for DANYELZA in Europe. There are no regulatory-based or sales-based milestone payments or royalty arrangements under this distribution agreement. The Company recognizes revenue when the customer obtains control of the product upon delivery to WEP. The Company invoices WEP based on the terms of the distribution agreement, where a portion is billed upon shipment of product and the unbilled portion is billed at a later date based on terms of the distribution agreement. The Company has an unconditional right to the unbilled portion of the receivable and the Company estimates that the receivable will be collected within one year and therefore has recorded the balance at June 30, 2023, within accounts receivable on the Consolidated Balance Sheets. License revenue In December 2020, the Company entered into a development and commercialization arrangement with SciClone International Pharmaceuticals Ltd., or SciClone, for certain indications of DANYELZA and omburtamab for Greater China, including Mainland China, Taiwan, Hong Kong and Macau. Based on the terms of the agreement, the Company may receive regulatory-based milestone payments up to $40,000,000 and sales-based milestone payments up to $60,000,000 and is entitled to royalties based upon the net sales generated by SciClone related to the product indications in the territory. In December 2022, the Company received a regulatory-based milestone payment of $15,000,000 for the conditional approval of DANYELZA in China. The Company determined that the achievement of the remaining regulatory-based milestones within the agreement are constrained as they are contingent upon regulatory approvals which are not within its control and therefore not deemed probable. The Company expects that the sales-based milestones and royalty payments will be recognized when the milestone is achieved or the related sales occur. The Company re-evaluates the transaction price each quarter and as uncertain events are resolved or other changes in circumstances occur, it assesses whether this resolves the constraint and it is appropriate to recognize revenue. In November 2020, we entered into an exclusive license and distribution agreement for DANYELZA and omburtamab with Takeda Israel, a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited covering the State of Israel, West Bank and Gaza Strip. Based on the terms of the arrangement, the Company may receive regulatory-based milestone payments up to $750,000, of which $250,000 has already been recognized, and sales-based milestone payments up to $500,000 and is entitled to royalties based upon the net sales generated by Takeda related to the product in the territory. The Company expects that the remaining regulatory-based and sales-based milestones will be recognized when the milestone is achieved, or the related sales occur. In December 2020, the Company entered into a distribution agreement for DANYELZA and omburtamab with Swixx BioPharma AG for the Eastern European territories Bosnia & Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Russia, Serbia, Slovakia and Slovenia. There are no regulatory-based or sales-based milestone payments or royalty arrangements under this distribution agreement. In May 2021, the Company entered into an exclusive distribution agreement with Adium Pharma S.A. (“Adium”) for Adium to be the exclusive distributor in Latin America of the Company’s antibodies omburtamab, if approved, and DANYELZA. Under the terms of the agreement, the Company may receive regulatory-based milestone payments up to an aggregate of $3,000,000. The Company received the first of these milestone payments totaling $1,000,000 in April 2022 upon the submission of the updated FDA Biologics License Application (“BLA”) dossier for DANYELZA. In addition, the Company is entitled to royalties based upon DANYELZA net sales generated by Adium in Latin America. The Company determined that the achievement of the remaining regulatory-based milestones within the agreement are constrained as they are contingent upon regulatory approvals which are not within the Company’s control and therefore not deemed probable. The agreement with Adium does not contain a regulatory-based milestone related to the Brazilian Health Regulatory Agency’s approval for marketing authorization, which was granted during the three months ended June 30, 2023. The Company expects that the sales-based milestones and royalty payments will be recognized when and if the milestones are achieved or the related sales occur. The Company reevaluates the transaction price each quarter and as uncertain events are resolved or other changes in circumstances occur, the Company assesses whether this resolves the constraint and it is appropriate to recognize revenue. The Company did not recognize license revenue in the three and six months ended June 30, 2023.
Segment Information	Segment Information The Company is engaged solely in the discovery, development, distribution and commercialization 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 From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, and are adopted by the Company as of the specific effective date. The Company adopted ASU 2022-04, ASU 2022-02, ASU 2022-01 and ASU 2021-08 effective January 1, 2023, and the adoption of these new standards did not have a material impact on the Company’s consolidated financial statements or disclosures. The Company has evaluated accounting pronouncements recently issued but not yet adopted and believes that these pronouncements do not apply to the Company’s operations and therefore will not have a material impact on the Company’s consolidated financial statements or disclosures.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	6 Months Ended
	Jun. 30, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of cash equivalents measured at fair value on recurring basis	The following tables present the Company’s fair value hierarchy for its cash equivalents, which are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at June 30, 2023 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 Total ​ $ — ​ $ 82,906 ​ $ — ​ $ 82,906 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 Using: ​ Level 1 Level 2 Level 3 Total Cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965 Total ​ $ — ​ $ 86,965 ​ $ — ​ $ 86,965

PRODUCT REVENUE, NET (Tables)

PRODUCT REVENUE, NET (Tables)	6 Months Ended
	Jun. 30, 2023
PRODUCT REVENUE, NET
Change in reserves for discounts and allowances	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contractual ​ ​ ​ ​ ​ ​ ​ Allowances and ​ ​ ​ ​ ​ ​ ​ Discounts ​ Government Rebates Returns ​ Total ​ (in thousands) Balance December 31, 2022 $ 33 ​ $ 2,905 ​ $ 44 ​ $ 2,982 Current provisions relating to sales in current year ​ 120 ​ ​ 5,897 ​ ​ 242 ​ ​ 6,259 Payments/credits relating to sales in current year ​ (113) ​ ​ (3,693) ​ ​ (220) ​ ​ (4,026) Balance June 30, 2023 $ 40 ​ $ 5,109 ​ $ 66 ​ $ 5,215

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2023
NET LOSS PER SHARE
Schedule of basic and diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ 2023 ​ 2022 2023 ​ 2022 ​ ​ ​ (in thousands, except per share amounts) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss (numerator) ​ $ (6,302) ​ $ (41,131) ​ $ (12,692) ​ $ (69,199) ​ Weighted-average shares (denominator), basic and diluted ​ 43,663 ​ 43,719 ​ 43,667 ​ 43,714 ​ Basic and diluted net loss per share ​ $ (0.14) ​ $ (0.94) ​ $ (0.29) ​ $ (1.58) ​

INVENTORIES (Tables)

INVENTORIES (Tables)	6 Months Ended
	Jun. 30, 2023
INVENTORIES
Schedule of inventories	Inventories consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2023 ​ December 31, 2022 ​ ​ ​ ​ ​ ​ Work In Progress ​ $ 13,849 ​ $ 11,317 Finished Goods ​ ​ 2,998 ​ ​ 666 Total Inventories ​ $ 16,847 ​ $ 11,983 ​ ​ ​ ​ ​ ​ ​ ​ Inventories are classified on the Consolidated Balance Sheets in each respective period (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2023 ​ December 31, 2022 CURRENT ASSETS ​ ​ ​ ​ ​ ​ Inventories ​ $ 5,187 ​ $ 6,702 Total recorded in Current Assets ​ ​ 5,187 ​ ​ 6,702 ​ ​ ​ ​ ​ ​ ​ NONCURRENT ASSETS ​ ​ ​ ​ ​ ​ Other assets ​ ​ 11,660 ​ ​ 5,281 Total recorded in Noncurrent Assets ​ ​ 11,660 ​ ​ 5,281 Total Inventories ​ $ 16,847 ​ $ 11,983

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	6 Months Ended
	Jun. 30, 2023
ACCRUED LIABILITIES
Summary of accrued short-term liabilities	Accrued liabilities as of June 30, 2023 and December 31, 2022, are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, December 31, ​ 2023 ​ 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued licensing, milestone and royalty payments ​ $ 2,777 ​ $ 4,002 Accrued clinical costs ​ 1,005 ​ 932 Accrued compensation and board fees ​ 2,510 ​ 2,445 Accrued manufacturing costs ​ ​ 4,671 ​ ​ 2,977 Accrued sales reserves ​ ​ 4,739 ​ ​ 2,474 Other ​ 450 ​ 411 Total ​ $ 16,152 ​ $ 13,241

LICENSE AGREEMENTS AND COMMIT_2

LICENSE AGREEMENTS AND COMMITMENTS (Tables)	6 Months Ended
	Jun. 30, 2023
LICENSE AGREEMENTS AND COMMITMENTS
Summary of significant license agreements, related commitments and milestone information	The Company has the following significant license agreements and related commitments which include all obligations that have been paid or accrued for the three and six months ended June 30, 2023 and 2022, and as of June 30, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid Cash paid Expense Expense Expense Expense ​ Accrued Accrued Accrued Accrued ​ ​ Six ​ Six ​ Three ​ Six ​ Three ​ Six ​ liabilities liabilities liabilities liabilities ​ ​ months ​ months ​ months ​ months ​ months ​ months ​ Current ​ Non-current ​ Current ​ Non-current ​ ​ ​ ended ​ ended ​ ended ​ ended ​ ended ​ ended ​ as of ​ as of ​ as of ​ as of ​ ​ ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ December 31, ​ December 31, ​ Agreements ​ 2023 ​ 2022 ​ 2023 ​ 2023 ​ 2022 ​ 2022 ​ 2023 ​ 2023 ​ 2022 ​ 2022 ​ MSK ​ $ 3,245 ​ $ 1,263 ​ $ 1,479 ​ $ 2,702 ​ $ 1,083 ​ $ 1,760 ​ $ 2,777 ​ $ 1,950 ​ $ 3,397 ​ $ 1,950 ​ CD33 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 300 ​ ​ — ​ ​ 300 ​ MabVax ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ SADA ​ ​ 605 ​ ​ 1,000 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 605 ​ ​ — ​ The below table represents the maximum clinical, regulatory or sales-based milestones as reflected within the agreements, certain of which have been paid in prior periods or are accrued as presented in the table above (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Maximum Maximum Maximum ​ ​ Clinical ​ Regulatory ​ Sales-based Agreements ​ Milestones ​ Milestones ​ Milestones MSK ​ $ 2,450 ​ $ 9,000 ​ $ 20,000 CD33 ​ ​ 550 ​ ​ 500 ​ ​ 7,500 MabVax ​ ​ 200 ​ ​ 1,200 ​ ​ — SADA ​ ​ 4,730 ​ ​ 18,125 ​ ​ 23,750
Maturities of operating lease liabilities	Maturities of operating lease liabilities at June 30, 2023, were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases ​ at June 30, 2023 Remainder of 2023 ​ $ 531 Years ending December 31, ​ ​ ​ 2024 ​ ​ 477 2025 ​ ​ 369 Total lease payments ​ ​ 1,377 Less: Imputed interest ​ ​ (132) Total operating lease liabilities at June 30, 2023 ​ $ 1,245 ​ Maturities of operating leases liabilities as of December 31, 2022, were as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating Leases Years ending December 31, at December 31, 2022 2023 ​ $ 997 2024 ​ ​ 490 2025 ​ ​ 419 Total lease payments ​ ​ 1,906 Less: Imputed interest ​ ​ (139) Total operating lease liabilities at December 31, 2022 ​ $ 1,767

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2023
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, 2022 7,079,767 ​ $ 21.27 ​ $ 3,112 ​ 6.45 Granted 1,744,900 ​ ​ 5.00 ​ ​ ​ ​ ​ Exercised ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Forfeited ​ (214,006) ​ ​ 10.93 ​ ​ ​ ​ ​ Outstanding and expected to vest at June 30, 2023 8,610,661 ​ $ 18.23 ​ $ 9,387 ​ 6.61 Exercisable at June 30, 2023 5,556,135 ​ ​ 20.12 ​ ​ 6,384 ​ 5.35
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, 2022 ​ 33,355 ​ $ 17.77 1.77 ​ Granted ​ 380,635 ​ ​ 4.81 ​ Vested ​ (8,846) ​ ​ 15.89 ​ ​ Forfeited ​ (40,310) ​ ​ 9.55 ​ ​ ​ Outstanding and expected to vest at June 30, 2023 ​ 364,834 ​ $ 5.20 2.46 ​

BASIS OF PRESENTATION - Accumul

BASIS OF PRESENTATION - Accumulated deficit (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
BASIS OF PRESENTATION
Accumulated deficit	$ (448,735)	$ (436,043)

BASIS OF PRESENTATION - Cash an

BASIS OF PRESENTATION - Cash and cash equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
BASIS OF PRESENTATION
Cash and cash equivalents	$ 87,909	$ 105,762

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Credit Risk (Details) - Credit Concentration Risk - Accounts Receivable - Three Customers	6 Months Ended
	Jun. 30, 2023 customer
Concentration risk
Number of customers	3
Concentration risk percentage (as a percent)	71%

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Inventory (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Inventory write-downs	$ 456

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair Value Measurement (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
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	82,906	$ 86,965
Recurring | Money market funds
Fair value measurements
Cash equivalents	82,906	86,965
Recurring | Level 2
Fair value measurements
Cash equivalents	82,906	86,965
Recurring | Level 2 | Money market funds
Fair value measurements
Cash equivalents	$ 82,906	$ 86,965

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Operating Leases (Details) $ in Thousands	Jun. 30, 2023 USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Residual value guarantees	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition - Product revenue, net (Details)	6 Months Ended
	Jun. 30, 2023
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Discount for prompt payment (as a percent)	2%

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition - License revenue (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2022	Nov. 30, 2020	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	May 31, 2021	Dec. 31, 2020
Agreements
Revenue			$ 20,751	$ 10,797	$ 41,002	$ 21,283
Development and commercialization arrangement | SciClone
Agreements
Maximum regulatory-based milestone payments receivable									$ 40,000
Maximum sales-based milestone payments receivable									$ 60,000
License
Agreements
Revenue				$ 1,000		$ 1,000
License | License and distribution agreement | Takeda Israel
Agreements
Maximum regulatory-based milestone payments receivable		$ 750
Maximum sales-based milestone payments receivable		500
License | Distribution Agreement | Adium
Agreements
Maximum regulatory-based milestone payments receivable								$ 3,000
License, Milestone | Development and commercialization arrangement | SciClone
Agreements
Revenue							$ 15,000
License, Milestone | License and distribution agreement | Takeda Israel
Agreements
Revenue		$ 250
License, Milestone | Distribution Agreement | Adium
Agreements
Revenue	$ 1,000

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment (Details)	6 Months Ended
	Jun. 30, 2023 segment
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Number of Operating Segments	1

PRODUCT REVENUE, NET - Geograph

PRODUCT REVENUE, NET - Geographic Breakout and Discounts and Allowances (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue
Revenue	$ 20,751	$ 10,797	$ 41,002	$ 21,283
Change in reserves for discounts and allowances
Discounts, Balance at beginning of period			33
Discounts, Current provisions relating to sales in current year			120
Discounts, Payments/credits relating to sales in current year			(113)
Discounts, Balance at end of period	40		40
Contractual Allowances and Government Rebates, Balance at beginning of period			2,905
Contractual Allowances and Government Rebates, Current provisions relating to sales in current year			5,897
Contractual Allowances and Government Rebates, Payments/credits relating to sales in current year			(3,693)
Contractual Allowances and Government Rebates, Balance at end of period	5,109		5,109
Returns, Balance at beginning of period			44
Returns, Current provisions relating to sales in current year			242
Returns, Payments/credits relating to sales in current year			(220)
Returns, Balance at end of period	66		66
Reserves for discounts and allowances, Balance at beginning of period			2,982
Reserves for discounts and allowances, Current provisions relating to sales in current year			6,259
Reserves for discounts and allowances, Payments/credits relating to sales in current year			(4,026)
Reserves for discounts and allowances, Balance at end of period	5,215		5,215
Accounts receivable
Change in reserves for discounts and allowances
Reserves for discounts and allowances, Balance at beginning of period			508
Reserves for discounts and allowances, Balance at end of period	476		476
Accrued liabilities
Change in reserves for discounts and allowances
Reserves for discounts and allowances, Balance at beginning of period			2,474
Reserves for discounts and allowances, Balance at end of period	4,739		4,739
Product
Revenue
Revenue	20,751	9,797	41,002	20,283
Product, DANYELZA
Revenue
Revenue	20,751	9,797	41,002	20,283
Product, DANYELZA | United States
Revenue
Revenue	15,851	9,021	32,685	18,453
Product, DANYELZA | Other countries
Revenue
Revenue	4,900	$ 776	8,317	$ 1,830
Product, DANYELZA | CHINA
Revenue
Revenue	$ 3,535		3,535
Product, DANYELZA | Europe
Revenue
Revenue			$ 2,516

PRODUCT REVENUE, NET - Concentr

PRODUCT REVENUE, NET - Concentrations (Details) - Customer Concentration Risk - Revenue - Product	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
McKesson
Concentration risk
Concentration risk percentage (as a percent)	46%	71%	44%	64%
AmerisourceBergen
Concentration risk
Concentration risk percentage (as a percent)	18%	10%	23%	17%
Cardinal Health
Concentration risk
Concentration risk percentage (as a percent)	12%	11%	12%	11%
SciClone
Concentration risk
Concentration risk percentage (as a percent)	20%		12%

PRODUCT REVENUE, NET - Addition

PRODUCT REVENUE, NET - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Revenue
Revenue	$ 20,751	$ 10,797	$ 41,002	$ 21,283
Accounts receivable	19,118		19,118		$ 12,531
Product
Revenue
Revenue	20,751	9,797	41,002	20,283
Product, DANYELZA
Revenue
Revenue	20,751	9,797	41,002	20,283
Product, DANYELZA | Distribution partner
Revenue
Revenue	2,620	738	3,387	1,354
Product, DANYELZA | WEP
Revenue
Revenue	2,516	$ 0	2,516	$ 0
Accounts receivable	$ 2,307		2,307
Allowance for doubtful accounts			$ 133

NET LOSS PER SHARE - Basic and

NET LOSS PER SHARE - Basic and diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
NET LOSS PER SHARE
Net income /(loss) (numerator), Basic (in dollars)	$ (6,302)	$ (41,131)	$ (12,692)	$ (69,199)
Net income /(loss) (numerator), Diluted (in dollars)	$ (6,302)	$ (41,131)	$ (12,692)	$ (69,199)
Weighted-average shares (denominator), basic (in shares)	43,663,112	43,718,748	43,667,385	43,713,967
Weighted-average shares (denominator), diluted (in shares)	43,663,112	43,718,748	43,667,385	43,713,967
Basic net loss per share (in dollars per share)	$ (0.14)	$ (0.94)	$ (0.29)	$ (1.58)
Diluted net loss per share (in dollars per share)	$ (0.14)	$ (0.94)	$ (0.29)	$ (1.58)

NET LOSS PER SHARE - Anti-dilut

NET LOSS PER SHARE - Anti-dilutive securities (Details) - shares	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
NET LOSS PER SHARE
Potentially dilutive securities outstanding	8,975,495	6,972,558

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Inventories
Work In Progress	$ 13,849	$ 11,317
Finished Goods	2,998	666
Total Inventories	16,847	11,983
CURRENT ASSETS
Inventories	5,187	6,702
NONCURRENT ASSETS
Inventories, Noncurrent	11,660	5,281
Inventory write-downs	456
Other long-term assets
Inventories
Work In Progress	11,660	5,281
NONCURRENT ASSETS
Inventories, Noncurrent	$ 11,660	$ 5,281

INTANGIBLE ASSETS, NET (Details

INTANGIBLE ASSETS, NET (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
INTANGIBLE ASSETS, NET
Intangible assets, net	$ 2,809	$ 2,986
Accumulated amortization	$ 491	$ 314
Amortization period	10 years
Forecasted amortization expense
2023	$ 355
2024	355
2025	355
2026	355
2027	355
Thereafter	$ 1,034

ACCRUED LIABILITIES (Details)

ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Accrued short-term liabilities
Accrued licensing milestone and royalty payments	$ 2,777	$ 4,002
Accrued clinical costs	1,005	932
Accrued compensation and board fees	2,510	2,445
Accrued manufacturing costs	4,671	2,977
Accrued sales reserves	4,739	2,474
Other	450	411
Total	$ 16,152	$ 13,241

LICENSE AGREEMENTS AND COMMIT_3

LICENSE AGREEMENTS AND COMMITMENTS - MSK License Agreement (Details) - MSK $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($) agreement
Agreements
Number of license agreements | agreement	3
License Agreement
Agreements
Annual minimum royalties payable	$ 80
Maximum Clinical Milestones	2,450
Maximum Regulatory Milestones	9,000
Maximum Sales-based Milestones	$ 20,000
Minimum term of license agreement	15 years

LICENSE AGREEMENTS AND COMMIT_4

LICENSE AGREEMENTS AND COMMITMENTS - SADA License Agreement (Details) - SADA License Agreement - MSK and MIT $ in Thousands	Jun. 30, 2023 USD ($)
Agreements
Annual minimum royalties payable from tenth anniversary	$ 40
Annual minimum royalties payable once patent has been issued	60
Maximum sales based milestone payments due for each construct previously generated	$ 60,000

LICENSE AGREEMENTS AND COMMIT_5

LICENSE AGREEMENTS AND COMMITMENTS - Summary of Significant Agreements and Commitments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financial statement information
Accrued liabilities, current	$ 16,152,000		$ 16,152,000		$ 13,241,000
Accrued liabilities, noncurrent	2,250,000		2,250,000		2,250,000
Gross intangible assets related to Danyelza	2,809,000		2,809,000		2,986,000
License Agreement | MSK
Financial statement information
Cash paid			3,245,000	$ 1,263,000
Expense	1,479,000	$ 1,083,000	2,702,000	1,760,000
Accrued liabilities, current	2,777,000		2,777,000		3,397,000
Accrued liabilities, noncurrent	1,950,000		1,950,000		1,950,000
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
License Agreement | MabVax
Milestones
Maximum Clinical Milestones	200,000		200,000
Maximum Regulatory Milestones	1,200,000		1,200,000
CD33 License Agreement | MSK
Financial statement information
Accrued liabilities, noncurrent	300,000		300,000		300,000
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
SADA License Agreement | MSK and MIT
Financial statement information
Cash paid	605,000		605,000	$ 1,000,000
Accrued liabilities, current					$ 605,000
Milestones
Maximum Clinical Milestones	4,730,000		4,730,000
Maximum Regulatory Milestones	18,125,000		18,125,000
Maximum Sales-based Milestones	$ 23,750,000		$ 23,750,000

LICENSE AGREEMENTS AND COMMIT_6

LICENSE AGREEMENTS AND COMMITMENTS - Lease agreements (Details) $ in Thousands	1 Months Ended
	Feb. 28, 2019 USD ($) ft²	Nov. 01, 2021 USD ($)	Aug. 31, 2020	Dec. 31, 2019 ft²	Jan. 31, 2018 USD ($)
Manufacturing facility, Indiana
Leases
Lease term			2 years
Laboratory, New Jersey
Leases
Leased area (in square feet) | ft²	4,548
Additional leased area (in square feet) | ft²				235
Lease term	3 years
Option to extend	true
Option to extend, period	2 years
Fixed rent payable per annum	$ 177
Lease payable per month	$ 15
Corporate headquarters, New York
Leases
Lease term					6 years
Fixed rent payable per annum					$ 384
Lease payable per month					$ 32
Office space, Denmark
Leases
Lease term		4 years
Lease payable per month		$ 41

LICENSE AGREEMENTS AND COMMIT_7

LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Leases
Total operating lease costs	$ 220	$ 701	$ 560	$ 1,406
Cash paid for amounts included in the measurement of lease liabilities	266	601	525	1,208
Research and development expense
Leases
Total operating lease costs	163	641	446	1,279
Selling, general, and administrative expense
Leases
Total operating lease costs	$ 57	$ 60	$ 114	$ 127

LICENSE AGREEMENTS AND COMMIT_8

LICENSE AGREEMENTS AND COMMITMENTS - Lease maturities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Maturities of operating lease liabilities
Remainder of 2023	$ 531
First fiscal year	477	$ 997
Second fiscal year	369	490
Third fiscal year		419
Total lease payments	1,377	1,906
Less: Imputed interest	(132)	(139)
Total operating lease liabilities at end of period	$ 1,245	$ 1,767
Operating Lease, Liability, Statement of Financial Position	Operating lease liabilities, current portion, Operating lease liabilities, long-term portion	Operating lease liabilities, current portion, Operating lease liabilities, long-term portion

LICENSE AGREEMENTS AND COMMIT_9

LICENSE AGREEMENTS AND COMMITMENTS - Lease term and discount rate (Details)	Jun. 30, 2023	Dec. 31, 2022
LICENSE AGREEMENTS AND COMMITMENTS
Weighted average remaining lease term	1 year 11 months 23 days	2 years 4 months 9 days
Weighted average discount rate	8.40%	8.30%

LICENSE AGREEMENTS AND COMMI_10

LICENSE AGREEMENTS AND COMMITMENTS - Severance Related Benefits (Details) - Former Chief Executive Officer - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Apr. 27, 2022	Jun. 30, 2022	Jun. 30, 2022
Severance Agreement
Cash compensation for salary and certain benefits continuation	$ 1,589
Total charge related to executive management change		$ 10,875	$ 10,875
Stock options
Severance Agreement
Stock-based compensation expenses		$ 9,286	$ 9,286

LICENSE AGREEMENTS AND COMMI_11

LICENSE AGREEMENTS AND COMMITMENTS - Legal matters (Details)	Aug. 25, 2021 stockholder
Lawsuit filed by shareholder in the U.S. District Court, Southern District of New York, on August 25, 2021
Legal Matters
Number of stockholders that filed lawsuit	1

STOCKHOLDERS' EQUITY - Authoriz

STOCKHOLDERS' EQUITY - Authorized, Common and Preferred Stock (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023 USD ($) Vote $ / shares shares	Dec. 31, 2022 USD ($) Vote $ / shares shares
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	1
Common stock dividends issued | $	$ 0	$ 0
Common stock, shares issued	43,620,192	43,670,109
Preferred stock, shares issued	0	0

STOCKHOLDERS' EQUITY - Stock Gr

STOCKHOLDERS' EQUITY - Stock Grant Agreements with Non Employees (Details) $ in Thousands	1 Months Ended					3 Months Ended	12 Months Ended	37 Months Ended
	Jun. 30, 2023 USD ($) shares	Apr. 30, 2023	Jul. 31, 2022 USD ($) individual shares	Jul. 31, 2020 USD ($) individual	Apr. 30, 2020 USD ($) individual agreement shares	Jun. 30, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Apr. 30, 2023 shares
Share-Based Compensation Awards
Retirement of treasury shares, Reduction in outstanding stock and reduction of APIC (in dollars)						$ 480
SADA License Agreement | MSK and MIT
Share-Based Compensation Awards
Impairment charge							$ 1,051
Retirement of treasury shares, Reduction in outstanding stock and reduction of APIC (in dollars)	$ 480		$ 963
SADA License Agreement | MSK and MIT | Researchers, Employees of MSK
Share-Based Compensation Awards
Number of individuals | individual				2
Notes receivable, noncurrent				$ 2,610
Notes receivable interest rate (as a percent)				1%
Number of individuals that repaid note | individual			1
SADA License Agreement | MSK and MIT | Nonemployees | Researchers, Employees of MSK
Share-Based Compensation Awards
Number of stock grant agreements entered into | agreement					2
Number of individuals | individual					2
Vested (in shares) | shares								213,996
Vested (as a percent)		20%			40%
Remaining vesting percentage					60%
SADA License Agreement | MSK and MIT | Nonemployees | Researchers, Employees of MSK | Research and development expense
Share-Based Compensation Awards
Non-cash expense in connection with equity issuance to non-employees					$ 7,376
Unrecognized compensation	$ 0					$ 0
SADA License Agreement | MSK and MIT | Nonemployees | Researchers, Employees of MSK | Tranche two
Share-Based Compensation Awards
Vesting period					3 years
Common Stock
Share-Based Compensation Awards
Number of shares exchanged | shares						58,763
Common Stock | SADA License Agreement | MSK and MIT
Share-Based Compensation Awards
Number of shares exchanged | shares	58,763		57,887
Common Stock | SADA License Agreement | MSK and MIT | Nonemployees | Researchers, Employees of MSK
Share-Based Compensation Awards
Issuance of common stock to non-employees (in shares) | shares					213,996

SHARE-BASED COMPENSATION - 2015

SHARE-BASED COMPENSATION - 2015 Plan (Details) - 2015 Plan - shares	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2015
Share-Based Compensation Awards
Shares reserved for issuance pursuant to the plan		4,500,000
Vesting period	4 years

SHARE-BASED COMPENSATION - 2018

SHARE-BASED COMPENSATION - 2018 Plan (Details) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2018
Stock options
Share-Based Compensation Awards
Term of award	10 years
2018 Plan
Share-Based Compensation Awards
Shares reserved for issuance pursuant to the plan			5,500,000
2018 Plan | Maximum
Share-Based Compensation Awards
Annual increase on share reserve (as a percent)		4%
2018 Plan | Stock options | Minimum
Share-Based Compensation Awards
Vesting period		1 year
2018 Plan | Stock options | Maximum
Share-Based Compensation Awards
Vesting period		4 years
2018 Plan | Stock options | Employees and nonemployees owning less than 10% of voting power
Share-Based Compensation Awards
Term of award		10 years
2018 Plan | Stock options | Participants owning more than 10% of voting power
Share-Based Compensation Awards
Term of award		5 years
2018 Plan | Stock options | Participants owning more than 10% of voting power | Minimum
Share-Based Compensation Awards
Ownership (as a percent)	10%	10%
Option price as percentage of fair market value of common stock on the date of grant		110%

SHARE-BASED COMPENSATION - Stoc

SHARE-BASED COMPENSATION - Stock-based compensation expense - Options (Details) - Stock options - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Former Chief Executive Officer
Share-Based Compensation Awards
Stock-based compensation expenses		$ 9,286		$ 9,286
Employees and directors
Share-Based Compensation Awards
Stock-based compensation expenses	$ 3,447	13,549	$ 8,564	18,566
Share based compensation acceleration cost			1,706
Employees and directors | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	1,274	2,002	3,454	3,781
Employees and directors | Selling, general, and administrative
Share-Based Compensation Awards
Stock-based compensation expenses	$ 2,173	$ 11,547	$ 5,110	$ 14,785

SHARE-BASED COMPENSATION - St_2

SHARE-BASED COMPENSATION - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Options
Outstanding at beginning of period (in shares)			7,079,767
Granted (in shares)	208,200	425,000	1,744,900	425,000
Forfeited, shares (in shares)			(214,006)
Outstanding at end of period (in shares)	8,610,661		8,610,661		7,079,767
Exercisable at end of period (in shares)	5,556,135		5,556,135
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)			$ 21.27
Granted (in dollars per share)			5
Forfeited (in dollars per share)			10.93
Outstanding at end of period (in dollars per share)	$ 18.23		18.23		$ 21.27
Exercisable at end of period (in dollars per share)	$ 20.12		$ 20.12
Aggregate intrinsic value and Weighted average remaining contractual life (years)
Outstanding (in dollars)	$ 9,387		$ 9,387		$ 3,112
Exercisable (in dollars)	$ 6,384		$ 6,384
Outstanding (in years)			6 years 7 months 9 days		6 years 5 months 12 days
Exercisable (in years)			5 years 4 months 6 days

SHARE-BASED COMPENSATION - St_3

SHARE-BASED COMPENSATION - Stock option grants (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Compensation Awards
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 5.50	$ 6.28	$ 3.65	$ 6.28
Granted (in shares)	208,200	425,000	1,744,900	425,000
Senior executives and certain other employees under retention program
Share-Based Compensation Awards
Granted (in shares)			1,105,500
Stock options
Share-Based Compensation Awards
Term of award	10 years
Stock options | Senior executives and certain other employees under retention program
Share-Based Compensation Awards
Granted (in shares)	124,500
Risk-free interest rate (as a percent)	3.90%
Expected term (in years)	6 years 3 months
Stock options | Non-executive directors
Share-Based Compensation Awards
Granted (in shares)	83,700
Vesting period	1 year
Risk-free interest rate (as a percent)	3.90%
Expected term (in years)	5 years 6 months
Stock options | Tranche one | Senior executives and certain other employees under retention program
Share-Based Compensation Awards
Vesting period	1 year
Vesting (as a percent)	25%
Stock options | Tranche two | Senior executives and certain other employees under retention program
Share-Based Compensation Awards
Vesting period	36 months

SHARE-BASED COMPENSATION - St_4

SHARE-BASED COMPENSATION - Stock option unrecognized compensation (Details) - Stock options $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($)
Unrecognized compensation related to employee stock options
Unrecognized compensation	$ 20,523
Expected vesting period	2 years 8 months 26 days

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock Unit Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Senior executives and certain other employees under retention program
Restricted stock units issued and outstanding
Granted (in shares)			380,635
RSUs
Share-Based Compensation Awards
Stock-based compensation expenses	$ 169	$ 84	$ 356	$ 158
Restricted stock units issued and outstanding
Outstanding and expected to vest at beginning of period (in shares)			33,355
Granted (in shares)			380,635
Vested (in shares)			(8,846)
Forfeited (in shares)			(40,310)
Outstanding and expected to vest at end of period (in shares)	364,834		364,834		33,355
Weighted average grant price
Weighted average grant price, Outstanding and expected to vest, Beginning of period (in dollars per share)			$ 17.77
Weighted average grant price, Granted (in dollars per share)			4.81
Weighted average grant price, Vested (in dollars per share)			15.89
Weighted average grant price, Forfeited (in dollars per share)			9.55
Weighted average grant price, Outstanding and expected to vest, End of period (in dollars per share)	$ 5.20		$ 5.20		$ 17.77
Unrecognized compensation	$ 1,596		$ 1,596
Weighted average remaining vesting life			2 years 5 months 15 days		1 year 9 months 7 days
RSUs | Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	98	74	$ 224	142
RSUs | Selling, general, and administrative
Share-Based Compensation Awards
Stock-based compensation expenses	$ 71	$ 10	$ 132	$ 16

INCOME TAXES - Loss before inco

INCOME TAXES - Loss before income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Domestic and foreign loss before income taxes:
LOSS BEFORE INCOME TAXES	$ (6,123)	$ (41,131)	$ (12,513)	$ (69,199)
Income tax expense
Current income tax provision	179	0	179	0
Deferred income tax provision	$ 0	$ 0	$ 0	$ 0

OTHER BENEFITS (Details)

OTHER BENEFITS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
United States
Benefit plan
Employer matching contribution to defined contribution plan (as a percent)	0%	0%	0%	0%
DENMARK
Benefit plan
Employer matching contribution to defined contribution plan (as a percent)	0%	0%	0%	0%
Costs for employee health insurance benefits	$ 0	$ 0	$ 0	$ 0

RESTRUCTURING CHARGE (Details)

RESTRUCTURING CHARGE (Details) - USD ($) $ in Thousands	3 Months Ended		5 Months Ended	6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	May 31, 2023	Jun. 30, 2023
RESTRUCTURING CHARGE
Reduction in workforce (as a percent)			35%
Restructuring charges				$ 4,482
Research and development expense
RESTRUCTURING CHARGE
Restructuring charges				3,346
Selling, general, and administrative
RESTRUCTURING CHARGE
Restructuring charges				1,136
Reduction in work force
RESTRUCTURING CHARGE
Severance termination benefits				2,776
Share based compensation acceleration cost				$ 1,706
Payments for restructuring	$ 1,105	$ 1,671