Verastem (VSTM) 10-K 28 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 25, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Entity File Number	001-35403
Entity Registrant Name	Verastem, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-3269467
Entity Address, Address Line One	117 Kendrick Street, Suite 500
Entity Address, City or Town	Needham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02494
City Area Code	781
Local Phone Number	292-4200
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	VSTM
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 696,704,277
Entity Common Stock, Shares Outstanding		186,329,612
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0001526119
Amendment Flag	false
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 21,252	$ 67,782
Short-term investments	79,004	73,444
Accounts receivable, net	516	239
Prepaid expenses and other current assets	4,968	3,473
Total current assets	105,740	144,938
Property and equipment, net	210	416
Right-of-use asset, net	2,302	2,726
Restricted cash	241	241
Long-term investments		5,995
Other assets	169	33
Total assets	108,662	154,349
Current liabilities:
Accounts payable	2,302	1,875
Accrued expenses	15,621	14,660
Lease liability, short-term	667	558
Total current liabilities	18,590	17,093
Non-current liabilities:
Convertible senior notes	249	19,051
Lease liability, long-term	2,264	2,931
Total liabilities	21,103	39,075
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized, no shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively
Common stock, $0.0001 par value; 300,000 shares authorized, 185,286 and 170,456 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively	19	17
Additional paid-in capital	751,217	707,715
Accumulated other comprehensive income	34	53
Accumulated deficit	(663,711)	(592,511)
Total stockholders' equity	87,559	115,274
Total liabilities and stockholders' equity	$ 108,662	$ 154,349

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2021	Dec. 31, 2020
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000	300,000
Common stock, shares issued	185,286	170,456
Common stock, shares outstanding	185,286	170,456

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue:
Total revenue	$ 2,053	$ 88,516	$ 17,456
Operating expenses:
Cost of sales - product		1,765	1,238
Cost of sales - intangible amortization		793	1,569
Cost of sales - Sale of COPIKTRA license and related assets		31,187
Research and development	39,347	41,376	45,778
Selling, general and administrative	24,115	62,755	101,212
Total operating expenses	63,462	137,876	149,797
Loss from operations	(61,409)	(49,360)	(132,341)
Other expense		(1,313)	(641)
Interest income	181	515	4,381
Interest expense	(9,972)	(15,794)	(20,608)
Loss on debt extinguishment		(1,580)
Net loss before income taxes	(71,200)	(67,532)	(149,209)
Income tax expense	0	(194)	0
Net loss	$ (71,200)	$ (67,726)	$ (149,209)
Net loss per share-basic	$ (0.41)	$ (0.44)	$ (2)
Net loss per share-diluted	$ (0.41)	$ (0.44)	$ (2)
Weighted average common shares outstanding used in computing:
Weighted average common shares outstanding used in computing net loss per share - basic	174,406	153,330	74,578
Weighted average common shares outstanding used in computing net loss per share - diluted	174,406	153,330	74,578
Net loss	$ (71,200)	$ (67,726)	$ (149,209)
Unrealized (loss) gain on available-for-sale securities	(19)	39	(113)
Comprehensive loss	(71,219)	(67,687)	(149,322)
Product revenue, net
Revenue:
Total revenue		15,232	12,339
License and collaboration revenue
Revenue:
Total revenue		2,912	$ 5,117
Copiktra license and related assets
Revenue:
Total revenue	1,447	70,000
Transition Services Revenue
Revenue:
Total revenue	$ 606	$ 372

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common stock	Additional paid-in capital	Accumulated other comprehensive (loss) income	Deficit accumulated during the development stage	Total
Balance at Dec. 31, 2018	$ 7	$ 499,741	$ 127	$ (375,576)	$ 124,299
Balance (in shares) at Dec. 31, 2018	73,806,344
Increase (Decrease) in Stockholders' Equity
Net loss				(149,209)	(149,209)
Unrealized gain (loss) on available-for-sale marketable securities			(113)		(113)
Conversion of Notes into common stock	$ 1	9,516			9,517
Conversion of Notes into common stock (in shares)	5,767,872
Change in fair value of conversion option of Notes on exchange		13,640			13,640
Issuance of common stock under Employee Stock Purchase Plan		439			439
Issuance of common stock under Employee Stock Purchase Plan (in shares)	341,701
Issuance of common stock resulting from vesting of restricted stock units		(68)			(68)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	109,707
Issuance of common stock resulting from exercise of stock options		130			130
Issuance of common stock resulting from exercise of stock options (in shares)	91,907
Stock-based compensation expense		8,539			8,539
Balance at Dec. 31, 2019	$ 8	531,937	14	(524,785)	7,174
Balance (in shares) at Dec. 31, 2019	80,117,531
Increase (Decrease) in Stockholders' Equity
Net loss				(67,726)	(67,726)
Unrealized gain (loss) on available-for-sale marketable securities			39		39
Conversion of Notes into common stock	$ 3	57,411			57,414
Conversion of Notes into common stock (in shares)	34,796,350
Change in fair value of conversion option of Notes on exchange		2,331			2,331
Issuance of common stock under Employee Stock Purchase Plan		407			407
Issuance of common stock under Employee Stock Purchase Plan (in shares)	358,193
Issuance of common stock resulting from vesting of restricted stock units		(1,120)			(1,120)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	421,695
Issuance of common stock resulting from exercise of stock options		2,578			2,578
Issuance of common stock resulting from exercise of stock options (in shares)	1,481,223
Issuance of common stock resulting from at-the-market transactions, net of issuance costs	$ 1	12,229			12,230
Issuance of common stock resulting from at-the-market transactions, net of issuance costs (in shares)	6,769,559
Issuance of common stock resulting from private investment in public equity offering, net of issuance costs	$ 5	93,824			93,829
Issuance of common stock resulting from private investment in public equity offering, net of issuance costs (in shares)	46,511,628
Stock-based compensation expense		8,118			8,118
Balance at Dec. 31, 2020	$ 17	707,715	53	(592,511)	$ 115,274
Balance (in shares) at Dec. 31, 2020	170,456,179				170,456,000
Increase (Decrease) in Stockholders' Equity
Net loss				(71,200)	$ (71,200)
Unrealized gain (loss) on available-for-sale marketable securities			(19)		(19)
Conversion of Notes into common stock	$ 1	27,999			28,000
Conversion of Notes into common stock (in shares)	8,615,384
Issuance of common stock under Employee Stock Purchase Plan		182			182
Issuance of common stock under Employee Stock Purchase Plan (in shares)	110,060
Issuance of common stock resulting from vesting of restricted stock units		(90)			(90)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	2,585,054
Issuance of common stock resulting from exercise of stock options		905			905
Issuance of common stock resulting from exercise of stock options (in shares)	589,218
Issuance of common stock resulting from at-the-market transactions, net of issuance costs	$ 1	6,795			6,796
Issuance of common stock resulting from at-the-market transactions, net of issuance costs (in shares)	2,930,585
Stock-based compensation expense		7,711			7,711
Balance at Dec. 31, 2021	$ 19	$ 751,217	$ 34	$ (663,711)	$ 87,559
Balance (in shares) at Dec. 31, 2021	185,286,480				185,286,000

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
At-the-market equity offering program
Issuance of common stock, issuance costs	$ 55
Private Investment in Public Equity (PIPE)
Issuance of common stock, issuance costs	$ 6,171

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (71,200)	$ (67,726)	$ (149,209)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	206	531	429
Amortization of acquired intangible asset		793	1,569
Amortization of right-of-use asset and lease liability	(134)	(69)	181
Stock-based compensation expense	7,711	8,118	8,539
Loss on debt extinguishment		1,580
Amortization of deferred financing costs, debt discounts and premiums and discounts on available-for-sale marketable securities	9,331	10,319	7,131
Change in fair value of interest make whole provision for 2019 Notes		1,313	641
Changes in operating assets and liabilities:
Accounts receivable, net	(277)	2,285	(2,218)
Inventory		3,096	(2,769)
Prepaid expenses, other current assets and other assets	(1,558)	634	(877)
Accounts payable	623	(7,976)	(598)
Accrued expenses and other liabilities	1,796	(4,999)	(1,707)
Other long-term liabilities		(870)	370
Intangible assets & property, plant and equipment		19,465
Net cash used in operating activities	(53,502)	(33,506)	(138,518)
Investing activities
Purchases of property and equipment	(196)	(33)	(7)
Purchases of investments	(86,442)	(79,380)	(94,123)
Maturities of investments	86,725	32,050	183,743
Net cash provided by (used in) investing activities	87	(47,363)	89,613
Financing activities
Proceeds from long-term debt, net of issuance costs			9,670
Repayment of long-term, debt		(37,366)	(12,174)
Interest make-whole payments on the 2019 Notes		(1,763)	(438)
Proceeds from the exercise of stock options and employee stock purchase program	1,087	2,985	569
Settlement of restricted stock for tax withholdings	(925)	(285)	(68)
Proceeds from the issuance of common stock, net	6,723	106,059
Net cash provided by (used in) financing activities	6,885	69,630	(2,441)
Decrease in cash, cash equivalents and restricted cash	(46,530)	(11,239)	(51,346)
Cash, cash equivalents and restricted cash at beginning of period	68,023	79,262	130,608
Cash, cash equivalents and restricted cash at end of period	21,493	68,023	79,262
Supplemental disclosure
Cash paid for interest	1,007	5,126	12,424
Supplemental disclosure of non-cash investing and financing activities
Common stock issuance costs included in accounts payable and accrued expenses		15	15
Purchases of property and equipment included in accounts payable and accrued expenses		217
Change in fair value of conversion option of Notes on exchange		2,331	13,640
Settlement of restricted stock units for tax withholdings included in accrued expenses		835
5.00% Convertible Senior Second Lien Notes due 2048
Supplemental disclosure of non-cash investing and financing activities
Conversion of notes into common stock		$ 57,414	$ 9,517
Change in fair value of conversion option of Notes on exchange	13,600
5.00% Convertible Senior Third Lien Notes due 2048
Supplemental disclosure of non-cash investing and financing activities
Conversion of notes into common stock	$ 28,000

Nature of business

Nature of business	12 Months Ended
	Dec. 31, 2021
Nature of business
Nature of business	1. Nature of business Verastem, Inc. (the Company) is a late stage development-stage biopharmaceutical company, with ongoing registration directed trials, committed to advancing new medicines for patients battling cancer. The Company’s pipeline is focused on novel anticancer agents that inhibit critical signaling pathways in cancer that promote cancer cell survival and tumor growth, particularly RAF/MEK inhibition and FAK inhibition. On September 24, 2018, the Company’s first commercial product, COPIKTRA® (duvelisib), was approved by the U.S. Food and Drug Administration (the FDA) for the treatment of adult patients with certain hematologic cancers including relapsed or refractory chronic lymphocytic leukemia/ small lymphocytic lymphoma (CLL/SLL) after at least two prior therapies and relapsed or refractory follicular lymphoma (FL) after at least two prior systemic therapies. On August 10, 2020, the Company and Secura Bio, Inc. (Secura) entered into an asset purchase agreement (Secura APA). Pursuant to the Secura APA, the Company sold to Secura its exclusive worldwide license, including certain related assets for the research, development, commercialization, and manufacture in oncology indications of products containing COPIKTRA (duvelisib). The transaction closed on September 30, 2020. Refer to Note 14. License, collaboration and commercial agreements The consolidated financial statements include the accounts of Verastem Securities Company and Verastem Europe GmbH, wholly-owned subsidiaries of the Company. All financial information presented has been consolidated and includes the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company is subject to the risks associated with other life science companies, including, but not limited to, possible failure of preclinical testing or clinical trials, competitors developing new technological innovations, inability to obtain marketing approval of the Company’s product candidates, VS-6766 and defactinib, market acceptance and commercial success of the Company’s product candidates, VS-6766 and defactinib, following receipt of regulatory approval, and, protection of proprietary technology and the continued ability to obtain adequate financing to fund the Company’s future operations. If the Company does not obtain marketing approval and successfully commercialize its product candidates, VS-6766 and defactinib, following regulatory approval, it will be unable to generate product revenue or achieve profitability and may need to raise additional capital. The Company has historical losses from operations and anticipates that it will continue to incur losses as it continues the research and development of its product candidates. As of December 31, 2021, the Company had cash, cash equivalents, and investments of The Company expects to finance the future development costs of its clinical product portfolio with its existing cash, cash equivalents and investments, through future milestones and royalties received through the Secura APA or through strategic financing opportunities that could include, but are not limited to collaboration agreements, future offerings of its equity, or the incurrence of debt. However, there is no guarantee that any of these strategic or financing opportunities will be executed or executed on favorable terms, and some could be dilutive to existing stockholders. If the Company fails to obtain additional future capital, it may be unable to complete its planned preclinical studies and clinical trials and obtain approval of certain investigational product candidates from the FDA or foreign regulatory authorities.

Significant accounting policies

Significant accounting policies	12 Months Ended
	Dec. 31, 2021
Significant accounting policies
Significant accounting policies	2. Significant accounting policies Basis of presentation The accompanying financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) under the assumption that the Company will continue as a going concern for the next twelve months. Accordingly, they do not include any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern. Use of estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including estimates related to revenue recognition, including returns, rebates, and other pricing adjustments, accrued and prepaid clinical trial expense and other general accruals and stock-based compensation expense. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable. Actual results could differ from such estimates. Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available and regularly reviewed by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing drugs for the treatment of cancer. All material long-lived assets of the Company reside in the United States. Cash, cash equivalents and restricted cash The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist of a U.S. Government money market funds and corporate bonds and commercial paper of publicly traded companies. Cash equivalents are reported at fair value. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 December 31, 2020 Cash and cash equivalents ​ $ 21,252 ​ $ 67,782 Restricted cash ​ 241 ​ 241 Total cash, cash equivalents and restricted cash ​ $ 21,493 ​ $ 68,023 ​ Fair value of financial instruments The Company determines the fair value of its financial instruments based upon the fair value hierarchy, which prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs: ​ ​ ​ ​ Level 1 inputs Quoted prices in active markets for identical assets or liabilities that the Company can access at the measurement date. Level 2 inputs ​ Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ​ Level 3 inputs ​ Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. ​ ​ Items Measured at Fair Value on a Recurring Basis The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 19,302 ​ $ 19,302 ​ $ — ​ $ — ​ Short-term investments ​ ​ 79,004 ​ ​ — ​ ​ 79,004 ​ ​ — ​ Total financial assets ​ $ 98,306 ​ $ 19,302 ​ $ 79,004 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 65,610 ​ $ 60,611 ​ $ 4,999 ​ $ — ​ Short-term investments ​ 73,444 ​ — ​ 73,444 ​ — ​ Long-term investments ​ ​ 5,995 ​ ​ — ​ ​ 5,995 ​ ​ — ​ Total financial assets ​ $ 145,049 ​ $ 60,611 ​ $ 84,438 ​ $ — ​ ​ confirming that the relevant markets are active. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of December 31, 2021 and 2020. Fair Value of Financial Instruments ​ Note 10. Convertible Senior Notes Investments Investments and cash equivalents consist of investments in a U.S. Government money market funds, overnight repurchase agreements collateralized by government agency securities or U.S. Treasury securities, corporate bonds and commercial paper of publicly traded companies that are classified as available-for-sale pursuant to Accounting Standards Codification (ASC) Topic 320, Investments—Debt and Equity Securities . The Company classifies investments available to fund current operations as current assets on its consolidated balance sheets. Investments are carried at fair value with unrealized gains and losses included as a component of accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity, until such gains and losses are realized. The fair value of these securities is based on quoted prices for identical or similar assets. If a decline in the fair value is considered other-than-temporary, based on available evidence, the unrealized loss is transferred from other comprehensive loss to the consolidated statements of operations and comprehensive loss. The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers the intent to sell, or whether it is more likely than not that the Company will be required to sell, the investment before recovery of the investment’s amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to year end. Realized gains and losses are determined using the specific identification method and are included in interest income in the consolidated statements of operations and comprehensive loss. There were no realized gains or losses on investments for the years ended December 31, 2021, 2020 or 2019. There were three debt securities and one debt security in an unrealized loss position as of December 31, 2021 and December 31, 2020, respectively. None of these investments had been in an unrealized loss position for more than 12 months as of December 31, 2021, or December 31, 2020, respectively. The fair value of these securities as of December 31, 2021, and December 31, 2020, was $15.8 million and $6.0 million, respectively, and the aggregate unrealized loss was immaterial. The Company considered the decline in the market value for these securities to be primarily attributable to current economic conditions. As it was not more likely than not that the Company would be required to sell these securities before the recovery of their amortized cost basis, which may be at maturity, the Company did not consider these investments to be other-than-temporarily impaired as of December 31, 2021, and December 31, 2020, respectively. Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Total cash, cash equivalents & restricted cash: ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total investments ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 100,463 ​ $ 48 ​ $ (14) ​ $ 100,497 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 63,024 ​ $ — ​ $ — ​ $ 63,024 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 4,998 ​ $ 1 ​ $ — ​ $ 4,999 ​ Total cash, cash equivalents & restricted cash: ​ $ 68,022 ​ $ 1 ​ $ — ​ $ 68,023 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds and commercial paper (due within 1 year ) ​ $ 73,389 ​ $ 55 ​ $ — ​ $ 73,444 ​ Corporate bonds and commercial paper (due between 1 and 5 years ) ​ ​ 5,998 ​ ​ — ​ ​ (3) ​ ​ 5,995 ​ Total investments ​ $ 79,387 ​ $ 55 ​ $ (3) ​ $ 79,439 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 147,409 ​ $ 56 ​ $ (3) ​ $ 147,462 ​ ​ Concentrations of credit risk and off-balance sheet risk Cash and cash equivalents, investments, and trade accounts receivable are financial instruments that potentially subject the Company to concentrations of credit risk. The Company mitigates this risk by maintaining its cash and cash equivalents and investments with high quality, accredited financial institutions. The management of the Company’s investments is not discretionary on the part of these financial institutions. As of December 31, 2021, the Company’s cash, cash equivalents and investments were deposited at three financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. As of December 31, 2021, and 2020, there was one customer, Secura, and two customers, respectively that cumulatively made up more than 50% of the Company’s trade accounts receivable balance. The Company assesses the creditworthiness of all its customers and sets and reassesses customer credit limits to ensure collectability of any trade accounts receivable balances are assured. For the year ended December 31, 2021 and 2020, one customer, Secura, individually accounted for greater than 10% of the Company’s total revenues. Property and equipment Property and equipment consist of laboratory equipment, office furniture, computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Depreciation and amortization are calculated using the straight-line method over the following estimated useful lives of the assets: ​ ​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​ ​ Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of assets may not be recoverable. Recoverability is measured by comparison of the asset’s book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded through December 31, 2021. Research and development costs The Company expenses research and development costs to operations as incurred. Research and development expenses consist of: ● employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; ● external research and development expenses incurred under arrangements with third parties, such as CROs, clinical trial sites, manufacturing organizations and consultants, including the scientific advisory board; ● license fees; ● facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation of equipment, and laboratory supplies; and Stock-based compensation For service-based equity awards, the Company recognizes stock-based compensation expense for stock options, and restricted stock units (RSUs) issued to employees, directors, and consultants based on the grant date fair value of the awards on a straight-line basis over the requisite service period, which typically is the vest period. The Company recognized stock-based compensation for shares issued to employees under the Company’s employee stock purchase plan (ESPP) plan. The Company has granted performance-based RSUs and stock options with terms that allow the recipients to vest in a specific number of shares based upon the achievement of performance-based milestones as specified in the grants. Stock-based compensation expense associated with these performance-based RSUs and stock options is recognized if the performance condition is considered probable of achievement using the Company’s best estimates of the time to vesting for the achievement of the performance-based milestones. based vesting requirements are expensed utilizing an accelerated attribution model if achievement of the performance criteria is determined to be probable. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model that takes into account the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company applies the simplified method described in the Securities and Exchange Commission (SEC) Staff Accounting Bulletin (SAB) Topic 14.D.2 to calculate the expected term as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted to employees. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its population. The Company has not paid and do not anticipate paying cash dividends on the Company’s shares of common stock; therefore, the expected dividend yield is assumed to be zero. The computation of expected volatility is based on the historical volatility of the Company’s common stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company accounts for forfeitures as they occur. The Company issues shares under the Company’s employee stock purchase plan (ESPP) to employees. Stock-based compensation expense for discounted purchases under the ESPP is measured using the Black-Scholes model to compute the fair value of the lookback provision plus the purchase discount and is recognized as compensation expense over the offering period Leases Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances within the arrangement. A lease is identified where an arrangement conveys the right to control the use of identified property, plant, and equipment for a period of time in exchange for consideration. Leases which are identified within the scope of ASC 842 and which have a term greater than one year are recognized on the Company’s consolidated balance sheets as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. The Company has elected not to recognize leases with terms of one year or less on its consolidated balance sheets. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. However, certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rates to calculate the present value of lease payments. Incremental borrowing rates are the rates the Company incurs to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. In accordance with ASC 842, components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). The fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available. Entities may elect the practical expedient to not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company has elected to account for the lease and non-lease components of each of its operating leases as a single lease component and allocate all of the contract consideration to the lease component only. The lease component results in an operating right-of-use asset being recorded on the consolidated balance sheets and amortized on a straight-line basis as lease expense. Revenue Recognition Revenue from Contracts with Customers Product Revenue, Net Product Revenue, Net – The Company recognized revenue on sales of COPIKTRA when a customer obtains control of the product, which occurs at a point in time (typically upon delivery). Product revenues are recorded at the wholesale acquisition costs, net of applicable reserves for variable consideration. Components of variable consideration include trade discounts and allowances, Third-Party Payer chargebacks and discounts, government rebates, other incentives, such as voluntary co-pay assistance, product returns, and other allowances that are offered within contracts between the Company and customers, payors, and other indirect customers relating to the Company’s sale of COPIKTRA. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable or a current liability. These estimates take into consideration a range of possible outcomes based upon relevant factors such as customer contract terms, information received from third parties regarding the anticipated payor mix for COPIKTRA, known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled with respect to sales made. The amount of variable consideration which is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under contracts will not occur in a future period. The Company’s analyses contemplate the application of the constraint in accordance with ASC 606. For the years ended December 31, 2020 and 2019, the Company determined a material reversal of revenue would not occur in a future period for the estimates detailed below and, therefore, the transaction price was not reduced further. There was not any product revenue, net recorded for the year ended December 31, 2021. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Trade Discounts and Allowances: The Company generally provided customers with invoice discounts on sales of COPIKTRA for prompt payment, which are explicitly stated in the Company’s contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized. In addition, the Company compensated its specialty distributor customers for sales order management, data, and distribution services. The Company has determined such services are not distinct from the Company’s sale of COPIKTRA to the specialty distributor customers and, therefore, these payments have also been recorded as a reduction of revenue within the consolidated statements of operations and comprehensive loss for the years ended December 31, 2020 and 2019. There were no amounts recorded for the year ended December 31, 2021. Third-Party Payer Chargebacks, Discounts and Fees: The Company executed contracts with Third-Party Payers which allowed for eligible purchases of COPIKTRA at prices lower than the wholesale acquisition cost charged to customers who directly purchase the product from the Company. In some cases, customers charged the Company for the difference between what they paid for COPIKTRA and the ultimate selling price to the Third-Party Payers. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable, net. Chargeback amounts are generally determined at the time of resale to the qualified Third-Party Payer by customers, and the Company generally issues credits for such amounts within a few weeks of the customer’s notification to the Company of the resale. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at the end of each reporting period that the Company expects will be sold to Third-Party Payers, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. In addition, the Company compensated certain Third-Party Payers for administrative services, such as account management and data reporting. These administrative service fees have also been recorded as a reduction of product revenue within the consolidated statements of operations and comprehensive loss for the years ended December 31, 2020 and 2019. There were no amounts recorded for the year ended December 31, 2021. Government Rebates: The Company was subject to discount obligations under state Medicaid programs and Medicare. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses on the consolidated balance sheets. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom the Company will owe an additional liability under the Medicare Part D program. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel inventories at the end of each reporting period. Other Incentives: Other incentives which the Company offered include voluntary co-pay assistance programs, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive for product that has been recognized as revenue but remains in the distribution channel inventories at the end of each reporting period. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included as a component of accrued expenses on the consolidated balance sheets. Product Returns: Consistent with industry practice, the Company generally offers customers a limited right of return for product that has been purchased from the Company. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The Company estimates product return liabilities using available industry data and its own sales information, including its visibility into the inventory remaining in the distribution channel. Subject to certain limitations, the Company’s return policy allows for eligible returns of COPIKTRA for credit under the following circumstances: ● Receipt of damaged product; ● Shipment errors that were a result of an error by the Company; ● Expired product that is returned during the period beginning three months prior to the product’s expiration and ending six months after the expiration date; ● Product subject to a recall; and ● Product that the Company, at its sole discretion, has specified can be returned for credit. If taxes should be collected from customers relating to product sales and remitted to governmental authorities, they will be excluded from product revenue. The Company expenses incremental costs of obtaining a contract when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. Licenses and Sales of Intellectual Property Licenses of Intellectual Property - The Company may enter into collaboration and licensing arrangements for research and development, manufacturing, and commercialization activities with collaboration partners for the development and commercialization of its product candidates, which have components within the scope of ASC 606. The arrangements generally contain multiple elements or deliverables, which may include (i) licenses, or options to obtain licenses, to the Company’s intellectual property or sale of the Company’s license, (ii) research and development activities performed for the collaboration partner, (iii) participation on joint steering committees, and (iv) the manufacturing of commercial, clinical or preclinical material. Payments pursuant to these arrangements typically include non-refundable, upfront payments, milestone payments upon the achievement of significant development events, research and development reimbursements, sales milestones, and royalties on product sales. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period. The contracts into which the Company enters generally do not include significant financing components. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its collaboration and license agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract within the scope of ASC 606; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: a) the number of performance obligations based on the determination under step (ii) above; b) the transaction price under step (iii) above; c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above; and d) the measure of progress in step (v) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties on license arrangements, should be included in the transaction price as described further below. If a license to the Company’s intellectual property is determined to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. In assessing whether a promise or performance obligation is distinct from the other elements, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of its associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a promise for its intended purpose without the receipt of the remaining elements, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure as of progress of each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The measure of progress, and thereby periods over which revenue should be recognized, is subject to estimates by management and may change over the course of the arrangement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Customer Options: If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services such as research and development services or manufacturing services, the goods and services underlying the customer options are not considered to be performance obligations at the inception of the arrangement; rather, such goods and services are contingent on exercise of the option, and the associated option fees are not included in the transaction price. The Company evaluates customer options for material rights or options to acquire additional goods or services for free or at a discount. If a customer option is determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the estimated probability that the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone Payments: At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluate

Property and equipment, net

Property and equipment, net	12 Months Ended
	Dec. 31, 2021
Property and equipment, net
Property and equipment, net	3. Property and equipment, net Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2021 ​ 2020 Leasehold improvements ​ $ 146 ​ $ 146 ​ Furniture and fixtures ​ 1,074 ​ 1,074 ​ Computer equipment ​ 665 ​ 665 ​ ​ ​ 1,885 ​ 1,885 ​ Less: accumulated depreciation ​ (1,675) ​ (1,469) ​ Total property and equipment, net ​ $ 210 ​ $ 416 ​ ​ The Company recorded approximately $0.2 million, $0.5 million, and $0.4 million in depreciation expense for the years ended December 31, 2021, 2020, and 2019, respectively .

Accrued expenses

Accrued expenses	12 Months Ended
	Dec. 31, 2021
Accrued expenses
Accrued expenses	4. Accrued expenses Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 December 31, 2020 Research and development expenses ​ $ 9,311 ​ $ 5,176 ​ Compensation and related benefits ​ 3,892 ​ 5,930 ​ Professional fees ​ 785 ​ 615 ​ Consulting fees ​ 544 ​ 1,091 ​ Interest ​ ​ 3 ​ ​ 236 ​ Commercialization costs ​ 187 ​ 330 ​ Other ​ 899 ​ 1,282 ​ Total accrued expenses ​ $ 15,621 ​ $ 14,660 ​ ​

Long-term debt

Long-term debt	12 Months Ended
	Dec. 31, 2021
Long-term debt
Long-term debt	5. Long-term debt On March 21, 2017, the Company entered into a term loan facility of up to $25.0 million with Hercules Capital, Inc. (Hercules). The term loan facility was governed by a loan and security agreement, dated March 21, 2017 (the Original Loan Agreement). The Original Loan Agreement was amended on January 4, 2018, March 6, 2018, October 11, 2018, April 23, 2019, and November 14, 2019 (the Amended Loan Agreement) to increase the total borrowing limit under the Original Loan Agreement from up to $25.0 million to up to $75.0 million, pursuant to certain conditions of funding. The Amended Term Loan was scheduled to mature on December 1, 2022. On November 9, 2020, the Company repaid in full all principal, accrued and unpaid interest, fees, and expenses under the Amended Loan Agreement with Hercules in an aggregate amount of $37.4 million (the Payoff Amount). The Payoff Amount included the principal balance of $35.0 million, final payment fee of $1.8 million, prepayment penalty fee of $0.5 million, and accrued and unpaid interest of $0.1 million. On November 9, 2020 the Amended Loan Agreement was terminated along with Hercules’ commitment to provide funding under any future term loans. All liens on substantially all of the Company’s assets to secure the loans under the Amended Loan Agreement have been terminated and released. The Payoff Amount, excluding accrued interest, exceeded the carrying amount of the Hercules debt on November 9, 2020 by $1.6 million. As a result, the Company recorded a loss on debt extinguishment of $1.6 million included in the statements of operations and comprehensive loss for the year ended December 31, 2020. ​

Product revenue reserves and al

Product revenue reserves and allowances	12 Months Ended
	Dec. 31, 2021
Product revenue reserves and allowances
Product revenue reserves and allowances	​ ​ 6. Product revenue reserves and allowances From September 24, 2018 (the date of the Company’s U.S. commercial launch of COPIKTRA) through September 30, 2020 (the date the Company sold COPIKTRA to Secura), the Company’s sole source of product revenue was from the gross sales of COPIKTRA in the United States less provisions for product sales allowances and accruals. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade ​ Payer ​ Government ​ ​ ​ ​ ​ ​ ​ ​ discounts ​ chargebacks, ​ rebates and ​ ​ ​ ​ ​ ​ ​ ​ and ​ discounts ​ other ​ ​ ​ ​ ​ ​ ​ allowances and fees incentives Returns Total Balance at December 31, 2019 ​ $ 111 ​ $ 255 ​ $ 372 ​ $ 76 ​ $ 814 Provision related to sales in the current year ​ ​ 640 ​ ​ 1,820 ​ ​ 609 ​ ​ 307 ​ ​ 3,376 Adjustments related to prior period sales ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — Credits and payments made ​ ​ (728) ​ ​ (2,075) ​ ​ (914) ​ ​ (352) ​ ​ (4,069) Balance at December 31, 2020 ​ $ 23 ​ $ — ​ $ 67 ​ $ 31 ​ $ 121 Provision related to sales in the current year ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Adjustments related to prior period sales ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Credits and payments made ​ (23) ​ ​ — ​ ​ (67) ​ ​ (31) ​ (121) Ending balance at December 31, 2021 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ Trade discounts and Third-Party Payer chargebacks and discounts are recorded as a reduction to accounts receivable, net on the consolidated balance sheets. Trade allowances and Third-Party Payer fees, government rebates, other incentives and returns are recorded as a component of accrued expenses on the consolidated balance sheets.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases
Leases	7. Leases On April 15, 2014, the Company entered into a lease agreement for approximately 15,197 square feet of office and laboratory space in Needham, Massachusetts. The lease term commenced on April 15, 2014 and it was scheduled to expire on September 30, 2019. Effective February 15, 2018, the Company amended its lease agreement to relocate within the facility to another location consisting of 27,810 square feet of office space (the Amended Lease Agreement). The Amended Lease Agreement extends the expiration date of the lease from September 2019 through June 2025. Pursuant to the Amended Lease Agreement, the initial annual base rent amount is approximately $660,000, which increases during the lease term to $1.1 million for the last twelve-month period. The Company has accounted for its Needham, Massachusetts office space as an operating lease. The Company’s lease contains an option to renew and extend the lease terms and an option to terminate the lease prior to the expiration date. The Company has not included the lease extension or the termination options within the right-of-use asset and lease liability on the consolidated balance sheets as neither option is reasonably certain to be exercised. The Company’s lease includes variable non-lease components (e.g., common area maintenance, maintenance, consumables, etc.) that are not included in the right-of-use asset and lease liability and are reflected as an expense in the period incurred. The Company does not have any other operating or finance leases. In calculating the present value of future lease payments, the Company has elected to utilize its incremental borrowing rate based on the remaining lease term at the date of adoption of ASC 842. The Company has elected to account for lease components and associated non-lease components as a single lease component and has allocated all of the contract consideration to the lease components only. This will potentially result in the initial and subsequent measurement of the balances of the right-of-use asset and lease liability for leases being greater than if the policy election was not applied. As of December 31, 2021, a right-of-use asset of $2.3 million and lease liability of $2.9 million are reflected on the consolidated balance sheets. The elements of lease expense were as follows (dollar amounts in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ ​ 2021 ​ 2020 Lease Expense ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ ​ $ 885 ​ $ 885 Total Lease Expense ​ ​ $ 885 ​ $ 885 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ ​ $ 1,019 ​ $ 955 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ 3.5 Weighted average discount rate ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ 2022 ​ ​ ​ ​ ​ ​ 1,039 2023 ​ ​ ​ ​ ​ ​ 1,060 2024 ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ ​ $ 3,726 Less: Present value discount ​ ​ ​ ​ ​ ​ (795) Lease Liability ​ ​ ​ ​ ​ $ 2,931 ​

Common stock

Common stock	12 Months Ended
	Dec. 31, 2021
Common stock.
Common stock	8. Common stock As of December 31, 2021 and 2020, the Company had reserved the following shares of common stock for the issuance of common stock for vested restricted stock units, the exercise of stock options, employee stock purchase plan and Notes conversions to shares of common stock (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2021 ​ 2020 Shares reserved under equity compensation plans 36,234 25,114 ​ Shares reserved for inducement grants ​ 3,991 ​ 4,058 ​ Shares reserved for 2018 Notes ​ 42 ​ 42 ​ Shares reserved for 2020 Notes ​ — ​ 8,615 ​ Employee Stock Purchase Plan ​ 1,190 ​ 1,300 ​ Total shares reserved 41,457 39,129 ​ ​ Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors. Private Investment in Public Equity (PIPE) At-the-market equity offering programs On March 30, 2017, the Company established an at-the-market equity offering program pursuant to which it was able to offer and sell up to $35.0 million of its common stock at then-current market prices from time to time through Cantor, as sales agent. On August 28, 2017, the Company amended its sales agreement with Cantor to increase the maximum aggregate offering price of shares of common stock that can be sold under the at-the-market equity offering program to $75.0 million. The Company did not make any sales under this program during the year ended December 31, 2021. During the year ended December 31, 2020, the Company sold 6,769,559 shares under this program for net proceeds of approximately $12.2 million (after deducting commissions and other offering expenses). Through December 31, 2021, the Company has sold a total of 18,287,913 shares under this program for net proceeds of approximately $59.6 million (after deducting commissions and other offering expenses). In August 2021, the Company entered into a sales agreement with Cantor pursuant to which the Company can offer and sell up to $100.0 million of its common stock at the current market prices from time to time through Cantor as sales agent (August 2021 ATM). During the year-ended December 31, 2021, the Company sold 2,930,585 shares under the August 2021 ATM for net proceeds of approximately $6.8 million (after deducting commissions and other offering expenses).

Stock-based compensation

Stock-based compensation	12 Months Ended
	Dec. 31, 2021
Stock-based compensation
Stock-based compensation	9. Stock-based compensation Stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 2020 2019 Research and development ​ $ 2,099 ​ $ 1,935 ​ $ 1,501 ​ Selling, general and administrative ​ 5,612 ​ 6,183 ​ 7,038 ​ Total stock-based compensation expense ​ $ 7,711 ​ $ 8,118 ​ $ 8,539 ​ ​ All of the $7.7 million, $8.1 million, and $8.5 million of stock-based compensation expense recorded during the years ended December 31, 2021, 2020, and 2019, respectively, was recorded to additional paid-in capital. The Company has awards outstanding under two equity compensation plans, the 2021 Equity Incentive Plan (2021 Plan), and the Amended and Restated 2012 Incentive Plan (the 2012 Plan), as well as the inducement award program. As of December 31, 2021, there are no awards outstanding under the 2010 Equity Incentive Plan (the 2010 Plan). Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the individual plans. 2021 Plan 2012 Plan The 2012 Plan became effective immediately upon the closing of the Company’s IPO in February 2012. Upon effectiveness of the 2012 Plan, the Company ceased making awards under the 2010 Plan. The 2012 Plan initially allowed the Company to grant awards for up to 3,428,571 shares of common stock, plus the number of shares of common stock available for grant under the 2010 Plan as of the effectiveness of the 2012 Plan (which was an additional 30,101 shares), plus that number of shares of common stock related to awards outstanding under the 2010 Plan which terminate by expiration, forfeiture, cancellation or otherwise. The 2012 Plan included an “evergreen provision” that allowed for an annual increase in the number of shares of common stock available for issuance under the 2012 Plan. The annual increase was added on the first day of each year from 2013 through 2018 and was equal to the lesser of 1,285,714 shares of common stock and 4.0% of the number of shares of common stock outstanding, or a lesser amount as determined by the board of directors. On each of January 1, 2018, January 1, 2017 and January 1, 2016, the number of shares available for issuance under the 2012 Plan increased by 1,285,714 under this provision. On December 18, 2018, the shareholders of the Company approved the Amended and Restated 2012 Incentive Plan which increased the maximum number of shares available for issuance under the 2012 Plan to 16,628,425 and eliminated the evergreen provision. On May 19, 2020, the shareholders of the Company approved the Amended and Restated 2012 Incentive Plan which increased the maximum number of shares available for issuance by 13,000,000 shares. Awards under the 2012 Plan may include the following award types: incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, RSUs, other stock-based or cash-based awards and any combination of the foregoing. As of December 31, 2021, under the 2012 Plan, the Company has granted stock options for 22,098,207 shares of common stock, of which 8,837,324 have been forfeited and 2,198,469 have been exercised, and granted RSUs for 6,678,621 shares of common stock, of which 1,021,941 have been forfeited and 5,028,711 have vested. The exercise price of each option has been equal to the closing price of a share of the Company’s common stock on the grant date. Upon adoption of the 2021 Plan, the Company ceased issuing awards from the 2012 Plan. Inducement Award Program In December 2014, the Company established an inducement award program (in accordance with Nasdaq Listing Rule 5635(c)(4)) under which it may grant non-statutory stock options to purchase, and RSUs in respect of up to an aggregate of ​ Stock Options ​ Most options granted by the Company vest twenty-five percent (25%) one year from vesting start date and six and a quarter percent (6.25%) for each successive three-month period, thereafter (subject to acceleration of vesting in the event of certain change of control transactions) subject to the employee’s continued employment with, or service to, the Company on such vesting date and are exercisable for a period of ten years from the date of grant. A summary of the Company’s stock option activity and related information for the year ended December 31, 2021, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average exercise price per share Weighted-average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2020 12,690,745 ​ $ 3.90 6.5 ​ $ 3,390 ​ Granted 4,990,731 ​ ​ 2.50 ​ ​ ​ ​ ​ ​ Exercised (572,086) ​ ​ 1.58 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (845,292) ​ ​ 3.71 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2021 16,264,098 ​ $ 3.56 6.7 ​ $ 2,601 ​ Vested at December 31, 2021 9,218,745 ​ $ 4.38 4.9 ​ $ 2,150 ​ ​ ​ The fair value of each stock option was estimated using a Black-Scholes option-pricing model with the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 ​ 2020 ​ 2019 Risk-free interest rate 1.15 % ​ 0.60 % ​ 1.98 % Volatility 89 % ​ 96 % ​ 87 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 6.0 ​ ​ 6.0 ​ ​ 5.9 ​ ​ The Company recorded stock-based compensation expense associated with employee and non-employee stock options of $4.1 million, $4.3 million, and $7.1 million, for the years ended December 31, 2021, 2020, and 2019, respectively. The weighted-average grant date fair value of options granted in the years ended December 31, 2021, 2020, and 2019 was $1.82, $1.62, and $1.44 per share, respectively. The fair value of options that vested during the years ended December 31, 2021, 2020, and 2019 was $3.8 million, $7.4 million, and $7.3 million, respectively. The aggregate intrinsic value of options exercised (i.e., the difference between the market price at exercise and the price paid by employees to exercise the option) during the years ended December 31, 2021 and 2020 was $0.8 million and $1.0 million, respectively. At December 31, 2021, there was $10.7 million of total unrecognized compensation cost related to unvested stock options and the Company expects to recognize this cost over a remaining weighted-average period of 3.2 years. Restricted Stock Units (RSUs) Each RSU entitles the holder to receive one share of the Company’s common stock when the RSU vests. The RSUs generally vest (i) twenty-five percent (25%) one year from vesting start date and six and a quarter percent (6.25%) for each successive three-month period, thereafter, (ii) two tranches for 50% of the award with the second and final vesting date on the one year anniversary of the vesting commencement date and (iii) 100 percent within two years of the vesting commencement date. The RSUs are subject to acceleration of vesting in the event of certain change of control transactions and subject to the employee’s continued employment with, or service to, the Company on such vesting date. Compensation expense is recognized on a straight-line basis. A summary of RSU activity during the year ended December 31, 2021, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average grant date fair value per share Outstanding at December 31, 2020 ​ 2,649,317 ​ $ 1.73 ​ Granted ​ 2,629,312 ​ $ 2.46 ​ Vested ​ (2,204,485) ​ $ 1.66 ​ Forfeited/cancelled ​ ​ (269,140) ​ $ 2.11 ​ Outstanding at December 31, 2021 ​ 2,805,004 ​ $ 2.44 ​ ​ The Company recorded stock-based compensation expense associated with employee and non-employee RSUs of $3.5 million, $3.7 million, and $1.0 million, for the years ended December 31, 2021, 2020, and 2019, respectively. The total fair value of restricted stock units vested during the years ended December 31, 2021, 2020, and 2019 was approximately $3.7 million, $3.8 million, and $0.3 million, respectively. At December 31, 2021, there was $6.0 million of total unrecognized compensation cost related to unvested RSUs and the Company expects to recognize this cost over a remaining weighted-average period of 3.7 years. On March 27, 2020, the Company amended all outstanding stock options and RSUs awards held by employees (including executive officers), other than certain performance-based awards, to provide that, in the event of a change of control, such equity awards currently held by employees that are outstanding and unvested immediately prior to a change of control of the Company will become fully vested and, if applicable, exercisable immediately prior to, and subject to the consummation of, such change of control. The amendment was implemented to provide assurance to the Company’s existing employees and not in response to any change of control offer for the Company. The modification affected 93 employees and will result in incremental stock compensation expense of $0.2 million to be recognized over the remaining requisite service period for each award. The modification resulted in incremental stock compensation expense of $0.1 million recognized in the year ended December 31, 2021, and 2020. The Company modified all unvested equity awards held by employees included in the August 2020 Restructuring discussed in Note. 15 Restructurings Employee stock purchase plan At the Special Meeting of Stockholders, held on December 18, 2018, the stockholders approved the 2018 Employee Stock Purchase Plan (2018 ESPP). On June 21, 2019, the board of directors of the Company amended and restated the 2018 ESPP, to account for certain non-material changes to the plan’s administration (the Amended and Restated 2018 ESPP). The Amended and Restated 2018 ESPP provides eligible employees with the opportunity, through regular payroll deductions, to purchase shares of the Company’s common stock at 85% of the lesser of the fair market value of the common stock (a) on the date the option is granted, which is the first day of the purchase period, and (b) on the exercise date, which is the last business day of the purchase period. The Amended and Restated 2018 ESPP generally allows for two six-month purchase periods per year beginning in January and July, or such other periods as determined by the compensation committee of the Company’s board of directors. The Company has reserved 2,000,000 shares of common stock for the administration of the Amended and Restated 2018 ESPP. The fair value of shares expected to be purchased under the Amended and Restated 2018 ESPP was calculated using the Black-Scholes model with the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ ​ 2021 ​ 2020 ​ 2019 Risk-free interest rate 0.07 % ​ 1.04 % ​ 2.26 % Volatility 68 % ​ 109 % ​ 88 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​ ​ 0.5 ​ ​

Convertible Senior Notes

Convertible Senior Notes	12 Months Ended
	Dec. 31, 2021
Convertible Senior Notes
Convertible Senior Notes	10. Convertible Senior Notes 2018 Notes On October 17, 2018, the Company closed a registered direct public offering of $150.0 million aggregate principal amount of the Company’s 5.00% Convertible Senior Notes due 2048 (the 2018 Notes), for net proceeds of approximately $145.3 million. The 2018 Notes are governed by the terms of a base indenture for senior debt securities (the Base Indenture), as supplemented by the first supplemental indenture thereto (the Supplemental Indenture and together with the 2018 Base Indenture, the 2018 Indenture), each dated October 17, 2018, by and between the Company and Wilmington Trust, National Association, (Wilmington) as trustee. The 2018 Notes are senior unsecured obligations of the Company and bear interest at a rate of 5.00% per annum, payable semi-annually in arrears on May 1 and November 1 of each year, beginning on May 1, 2019. The 2018 Notes will mature on November 1, 2048, unless earlier repurchased, redeemed or converted in accordance with their terms, The 2018 Notes are convertible into shares of the Company’s common stock, par value $0.0001 per share, together, if applicable, with cash in lieu of any fractional share, at an initial conversion rate of 139.5771 shares of common stock per $1,000 principal amount of the 2018 Notes, which corresponds to an initial conversion price of approximately $7.16 per share of common stock and represents a conversion premium of approximately 15.0% above the last reported sale price of the common stock of $6.23 per share on October 11, 2018. Upon conversion, converting noteholders will be entitled to receive accrued interest on their converted 2018 Notes. To the extent the Company has insufficient authorized but unissued shares to settle conversions in shares of common stock, the Company would be required to settle the deficiency in cash. The Company will have the right, exercisable at its option, to cause all Notes then outstanding to be converted automatically if the “Daily VWAP” (as defined in the 2018 Indenture) per share of the Company’s common stock equals or exceeds 130% of the conversion price on each of at least 20 VWAP Trading Days (as defined in the 2018 Indenture), whether or not consecutive, during any 30 consecutive VWAP Trading Day period commencing on or after the date the Company first issued the 2018 Notes. The conversion rate is subject to adjustment from time to time upon the occurrence of certain events, including, but not limited to, the issuance of stock dividends and payment of cash dividends, but will not be adjusted for any accrued and unpaid interest. Prior to November 1, 2022, the Company will not have the right to redeem the 2018 Notes. On or after November 1, 2022, the Company may elect to redeem the 2018 Notes, in whole or in part, at a cash redemption price equal to the principal amount of the 2018 Notes to be redeemed, plus accrued and unpaid interest, if any. Unless the Company has previously called all outstanding 2018 Notes for redemption, the 2018 Notes will be subject to repurchase by the Company at the holders’ option on each of November 1, 2023, November 1, 2028, November 1, 2033, November 1, 2038 and November 1, 2043 (or, if any such date is not a business day, on the next business day) at a cash repurchase price equal to the principal amount of the 2018 Notes to be repurchased, plus accrued and unpaid interest, if any. If a “Fundamental Change” (as defined in the 2018 Indenture) occurs at any time, subject to certain conditions, holders may require the Company to purchase all or any portion of their 2018 Notes at a purchase price equal to 100% of the principal amount of the 2018 Notes to be purchased, plus accrued and unpaid interest. If a “Fundamental Change” occurs on or before November 1, 2022 and a holder elects to convert its Notes in connection with such change, such holder may be entitled to an increase in the conversion rate in certain circumstances as set forth in the Indenture. The Company assessed all terms and features of the 2018 Notes in order to identify any potential embedded features that would require bifurcation. As part of this analysis, the Company assessed the economic characteristics and risks of the 2018 Notes, including the conversion, put and call features. The conversion feature was initially bifurcated as an embedded derivative but subsequently qualified for a scope exception to derivative accounting upon the Company’s stockholders approving an increase in the number of authorized shares of Common Stock in December 2018. The Company determined that all other features of the 2018 Notes were clearly and closely associated with the debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company’s consolidated financial statements. The Company reassesses the features on a quarterly basis to determine if they require separate accounting. There have been no changes to the Company’s original assessment through December 31, 2021. 2019 Notes On November 14, 2019 and December 23, 2019, the Company entered into privately negotiated agreements to exchange approximately $114.3 million and $7.4 million, respectively, aggregate principal amount of the 2018 Notes for (i) approximately $62.9 million and $4.0 million, respectively, aggregate principal amount of 2019 Notes (ii) an aggregate of approximately $11.4 million and $0.7 million in 2018 Notes principal repayment and (iii) accrued interest on the 2018 Notes through November 14, 2019 and December 23, 2019, respectively. The 2019 Notes are governed by the terms of an indenture (the 2019 Indenture). The 2019 Notes are senior secured obligations of the Company and bear interest at 5.00% per annum, payable semi-annually in arrears on May 1 and November 1 of each year. The 2019 Notes will mature on November 1, 2048, unless earlier repurchased, redeemed or converted in accordance with the terms. The Company determined 2019 Notes exchange met the definition of a troubled debt restructuring under ASC 470-60, Troubled Debt Restructurings by Debtors The 2019 Notes were convertible into shares of the Company’s common stock, par value $0.0001 per share, together, if applicable, with cash in lieu of any fractional share, at an initial conversion rate of 606.0606 shares of common stock per $1,000 principal amount of the 2019 Notes, which corresponds to an initial conversion price of approximately $1.65 per share of common stock. The Company assessed all terms and features of the 2019 Notes in order to identify any potential embedded features that would require bifurcation. As part of this analysis, the Company assessed the economic characteristics and risks of the 2019 Notes, including the conversion, put and call features. In consideration of the 2019 Notes Interest Make-Whole Provision, the Company concluded the provision required bifurcation as a derivative. The fair value of the 2019 Interest Make-Whole Provision was determined using a Monte Carlo model. It was determined that the fair value of the derivative upon the November 14, 2019 and December 23, 2019 issuance of the 2019 Notes was $0.2 million in aggregate; and recorded this amount as a derivative liability and the offsetting amount as a debt discount as a reduction to the carrying value of the 2019 Notes on the closing dates. During the period November 14, 2019 to December 31, 2019, 2019 Note holders converted $9.5 million aggregate principal of 2019 Notes in exchange for 5,767,872 shares of common stock, $0.4 million of cash for 2019 Interest Make-Whole Provision payments, and accrued interest. As of December 31, 2019, the Company determined the fair value of the 2019 Interest Make-Whole Provision was $0.5 million. The Company recorded the change in the fair value of the 2019 Interest Make-Whole Provision for the period from November 14, 2019 to December 31, 2019 of $0.6 million as other expense on the consolidated statements of operations and comprehensive loss. During the first quarter of 2020, 2019 Note holders converted $57.4 million aggregate principal of 2019 Notes in exchange for 34,796,350 shares of common stock, $1.8 million of cash for the 2019 Note Interest Make-Whole Provision, and accrued interest. The Company recorded $1.3 million for the year ended December 31, 2020, as other expense for the change in fair value of the 2019 Notes Interest Make-Whole Provision in the consolidated statements of operations and comprehensive loss. The Company determined that all other features of the 2019 Notes were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's consolidated financial statements. As of March 31, 2020, all 2019 Notes have converted into shares of common stock. 2020 Notes On November 6, 2020, the Company entered into a privately negotiated agreement with an investor who was a holder of the Company’s 2018 Notes to exchange approximately $28.0 million aggregate principal amount of 2018 Notes for approximately $28.0 million aggregate principal amount of newly issued 5.00% Convertible Senior Notes due 2048 (the 2020 Notes). The issuance of the 2020 Notes closed on November 13, 2020. The 2020 Notes were governed pursuant to the Base Indenture between the Company and Wilmington, as trustee and collateral agent, dated as of October 17, 2018 as supplemented by the second supplemental indenture thereto dated as of November 13, 2020 (the 2020 Notes Supplemental Indenture and together with the Base Indenture, the 2020 Indenture). The Company had the right, exercisable at its option, to cause all 2020 Notes then outstanding to be converted automatically if the “Daily VWAP” (as defined in the 2020 Indenture) per share of the Company’s common stock equaled or exceeded 123.08% of the conversion price on each of at least 20 “VWAP Trading Days” (as defined in the 2020 Indenture), whether or not consecutive, during any 30 consecutive VWAP Trading Day period commencing on or after the date the Company first issued the 2020 Notes (2020 Notes Mandatory Conversion Option). The initial conversion rate for the 2020 Notes was 307.6923 shares of the Company’s common stock per $1,000 principal amount of the 2020 Notes, which is equivalent to an initial conversion price of approximately $3.25 per share. The conversion rate was subject to adjustment from time to time upon the occurrence of certain events, including, but not limited to, the issuance of stock dividends and payment of cash dividends, but was not subject to adjustment for any accrued and unpaid interest. Prior to November 1, 2023, the Company did not have the right to redeem the 2020 Notes. On or after November 1, 2023, the Company had the option to redeem the 2020 Notes, in whole or in part, at a cash redemption price equal to the principal amount of the 2020 Notes to be redeemed, plus accrued and unpaid interest, if any. Unless the Company had previously called all outstanding 2020 Notes for redemption, the 2020 Notes were subject to repurchase by the Company at the holders’ option on each of November 1, 2023, November 1, 2028, November 1, 2033, November 1, 2038 and November 1, 2043 (or, if any such date is not a business day, on the next business day) at a cash repurchase price equal to the principal amount of the 2020 Notes to be repurchased, plus accrued and unpaid interest, if any. The Company determined the 2020 Notes exchange met the definition of a debt modification under ASC 470-50, Modifications and Extinguishments The Company determined that all features of the 2020 Notes were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's consolidated financial statements On July 1, 2021, the Company exercised the Company’s 2020 Notes Mandatory Conversion Option for the aggregate principal amount of $28.0 million of the Company’s 2020 Notes. On July 16, 2021, the aggregate principal of $28.0 million of 2020 Notes was converted into 8,615,384 shares of common stock. As a result, as of September 30, 2021, all 2020 Notes have converted into shares of common stock. Upon conversion of the 2020 Notes, holders received a cash payment equal to the accrued and unpaid interest on the converted 2020 Notes. Pursuant to ASC 815-15-40-1, upon conversion, the Company recorded the remaining discount on the 2020 Notes of $7.8 million as interest expense in the statements of operations and comprehensive loss during the year ended December 31, 2021. All Notes The Company determined that the expected life of the 2018 Notes, 2019 Notes, and 2020 Notes was equal to the period through November 1, 2023, as this represents the point at which the 2018 Notes, 2019 Notes, and 2020 Notes were initially subject to repurchase by the Company at the option of the holders. Accordingly, for the 2018 Notes, the total debt discount, inclusive of the fair value of the embedded conversion feature derivative at issuance is being amortized using the effective interest method through November 1, 2023. For the 2019 Notes and 2020 Notes, the total debt discount, inclusive of the fair value of the embedded conversion feature derivative at issuance and change in fair value of conversion option upon exchange, was being amortized using the effective interest method through November 1, 2023. Pursuant to ASC 815-15-40-1, tatements of operations and comprehensive loss

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2021
Net Loss per Share
Net Loss per Share	11. Net Loss per Share ASC Topic 260, Earnings Per Share, The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 2019 Outstanding stock options ​ 16,264,098 12,690,745 17,258,524 ​ Outstanding restricted stock units ​ 2,805,004 ​ 2,649,317 ​ 678,089 ​ 2018 Notes ​ 41,873 ​ 41,873 ​ 3,950,032 ​ 2019 Notes ​ — ​ — ​ 34,796,363 ​ 2020 Notes ​ — ​ 8,615,384 ​ — ​ Employee stock purchase plan ​ 57,636 ​ 53,372 ​ 227,141 ​ Total potentially dilutive securities ​ 19,168,611 24,050,691 56,910,149 ​ ​

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2021
Income taxes
Income taxes	12. Income Taxes As of December 31, 2021, the Company had federal and state NOL carryforwards of approximately $410.6 million and $219.0 million, respectively, which are available to reduce future taxable income. The Company also had federal and state tax credits of $3.5 million and $1.3 million, respectively, which may be used to offset future tax liabilities. The NOL and tax credit carryforwards will expire at various dates through 2041, except for $214.9 million of federal NOL carryforwards which may be carried forward indefinitely. During the year ended December 31, 2020, the Company recorded income tax expense of $0.2 million, which primarily related to state income tax as a result of the sale of COPIKTRA license and related assets to Secura. Refer to Note 14. License, collaboration and commercial agreements For the years ended December 31, 2021, 2020, and 2019 income tax expense consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 2020 2019 Current tax expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ — ​ $ — ​ $ — State ​ — ​ 194 ​ — Current income tax expense ​ ​ — ​ ​ 194 ​ ​ — Deferred ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ — ​ ​ — ​ ​ — State ​ — ​ — ​ ​ — Deferred income tax expense ​ ​ — ​ ​ — ​ ​ — Total income tax expense $ — ​ $ 194 ​ $ — ​ A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2021 2020 Income tax benefit using U.S. federal statutory rate 21.00 % 21.00 % State tax benefit, net of federal benefit 3.01 % (8.55) % Research and development tax credits 2.71 % 2.84 % Permanent items (0.44) % (0.60) % Change in the valuation allowance (21.23) % 35.09 % NOL and tax credit expiration under Section 382 ​ (4.34) % (52.67) % Other (0.71) % 2.60 % ​ — % (0.29) % ​ ​ The principal components of the Company’s deferred tax assets and liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2021 2020 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 98,777 ​ $ 86,665 ​ Capitalized research and development ​ 1,276 ​ 1,565 ​ Research and development credits ​ 4,516 ​ 2,043 ​ Stock-based compensation ​ 4,200 ​ 4,041 ​ Installment sale ​ ​ 8,819 ​ ​ 9,981 ​ Lease liability ​ ​ 730 ​ ​ 950 ​ Other deferred tax assets ​ 411 ​ 680 ​ Total deferred tax assets ​ 118,729 ​ 105,925 ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Right-of-use asset ​ ​ (574) ​ ​ (742) ​ Debt discount ​ ​ (11) ​ ​ (2,245) ​ Other deferred tax liability ​ ​ (91) ​ ​ — ​ Total deferred tax liabilities ​ ​ (676) ​ ​ (2,987) ​ Net deferred tax asset prior to valuation allowance ​ ​ 118,053 ​ ​ 102,938 ​ Valuation allowance ​ (118,053) ​ (102,938) ​ Net deferred tax asset ​ $ — ​ $ — ​ ​ The Company has recorded a valuation allowance against its deferred tax assets at December 31, 2021 and 2020 because the Company’s management believes that it is more likely than not that these assets will not be fully realized. The increase in the valuation allowance of approximately $15.1. million in the year ended December 31, 2021, primarily relates to the generation of net operating losses and research and development credits. Section 382 of the Internal Revenue Code and similar provisions under state law limit the utilization of U.S. NOL carryforwards, state NOL carryforwards, Research and Development (R&D) credits, and Orphan Drug (OD) credits following certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%. Based on the Company’s analysis under Section 382, the Company believes that its federal NOL carryforwards, its state NOL carryforwards, R&D credits, and OD credits are limited by Section 382 and similar provisions under state law as of December 31, 2021. The portion of federal NOL carryforwards, state NOL carryforwards, R&D credits, and OD credits that were determined to be limited have been written off as of December 31, 2021. The remaining unused carryforwards and credits remain available for future periods. Due the Company’s full valuation allowance the write off of NOL carryforwards and R&D and OD credits did not have any impact to the statements of operation and comprehensive loss. The Company’s reserves related to taxes are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. From inception and through December 31, 2021, the Company had no unrecognized tax benefits or related interest and penalties accrued. The Company has not conducted a study of R&D credit carryforwards. This study may result in an adjustment to the Company’s R&D credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s R&D credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheet or statement of operations if an adjustment were required. The Company would recognize both accrued interest and penalties related to unrecognized benefits in income tax expense. The Company’s uncertain tax positions are related to years that remain subject to examination by relevant tax authorities. Since the Company is in a loss carryforward position, the Company is generally subject to examination by the U.S. federal, state and local income tax authorities for all tax years in which a loss carryforward is available.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and contingencies
Commitments and contingencies	13. Commitments and contingencies The Company has entered into a lease agreement for approximately 27,810 square feet of office space in Needham, Massachusetts. Please refer to Note 7. Leases Pursuant to the terms of various agreements, the Company may be required to pay various development, regulatory and commercial milestones. In addition, if any products related to these agreements are approved for sale, the Company may be required to pay significant royalties on future sales. The payment of these amounts, however, is contingent upon the occurrence of various future events, which have a high degree of uncertainty of occurring.

License, collaboration and comm

License, collaboration and commercial agreements	12 Months Ended
	Dec. 31, 2021
License, collaboration and commercial agreements
License, collaboration and commercial agreements	14. License, collaboration and commercial agreements Secura Bio, Inc. (Secura) On August 10, 2020, the Company and Secura signed the Secura APA and on September 30, 2020, the transaction closed. Pursuant to the Secura APA, the Company sold to Secura its exclusive worldwide license, including related assets, for the research, development, commercialization, and manufacture in oncology indications of products containing duvelisib. The sale included certain intellectual property related to duvelisib in oncology indications, certain existing duvelisib inventory, claims and rights under certain contracts pertaining to duvelisib. Pursuant to the Secura APA, Secura assumed all operational and financial responsibility for activities that were part of the Company’s duvelisib oncology program, including all commercialization efforts related to duvelisib in the United States and Europe, as well as the Company’s ongoing duvelisib clinical trials. Further, Secura assumed all obligations with existing collaboration partners developing and commercializing duvelisib, which include Yakult Honsha Co., Ltd. (Yakult), CSPC Pharmaceutical Group Limited (CSPC), and Sanofi. Additionally, Secura assumed all royalty payment obligations due under the amended and restated license agreement with Infinity (Infinity License Agreement). Pursuant to the terms of the Secura APA, Secura has paid the Company an up-front payment of $70.0 million in September 2020 and has agreed to pay the Company (i) regulatory milestone payments up to $45.0 million, consisting of a payment of $35.0 million upon receipt of regulatory approval of COPIKTRA in the United States for the treatment of peripheral T-cell lymphoma and a payment of $10.0 million upon receipt of the first regulatory approval for the commercial sale of COPIKTRA in the European Union for the treatment of peripheral T-cell lymphoma, (ii) sales milestone payments of up to $50.0 million, consisting of $10.0 million when total worldwide net sales of COPIKTRA exceed $100.0 million, $15.0 million when total worldwide net sales of COPIKTRA exceed $200.0 million and $25.0 million when total worldwide net sales of COPIKTRA exceed $300.0 million, (iii) low double-digit royalties on the annual aggregate net sales above $100.0 million in the United States, European Union, and the United Kingdom of Great Britain and Northern Ireland and (iv) 50% of all royalty, milestone and sublicense revenue payments payable to Secura under the Company’s existing license agreements with Sanofi, Yakult, and CSPC, and 50% of all royalty and milestone payments payable to Secura under any license or sublicense agreement entered into by Secura in certain jurisdictions. In connection with the Secura APA, the Company and Secura entered into a transition services agreement (Secura TSA). Under the terms of the Secura TSA, the Company provided certain support functions at Secura’s direction for a term of less than one year from the date of execution (Secura TSA Services). Services performed were paid at a mutually agreed upon rate. The Company evaluated the Secura APA and Secura TSA in accordance with ASC 606 as the Company concluded that the counterparty, Secura, is a customer. The Company identified the following performance obligations under the Secura APA and Secura TSA: ● a bundled performance obligation consisting of delivery of the duvelisib global license and intellectual property, certain existing duvelisib inventory, certain duvelisib contracts and clinical trials, certain regulatory approvals, and certain regulatory documentation and books and records (the Bundled Secura Performance Obligation); and ● Secura TSA Services. The Company concluded that the duvelisib global license and intellectual property were not distinct within the context of the contract (i.e. separately identifiable) because the other assets including certain existing duvelisib inventory, certain duvelisib contracts and clinical trials, certain regulatory approval, and certain regulatory documentation and books and records do not have stand-alone value from other duvelisib global license and intellectual property and Secura could not benefit from them without the duvelisib global license and intellectual property. Consistent with the guidance under ASC 606-10-25-16A, the Company disregarded immaterial promised goods and services when determining performance obligations. The Company has determined that the upfront payment of $70.0 million, future potential milestone payments and royalties including from Secura’s sublicensees should be allocated to the delivery of the Bundled Secura Performance Obligation. The Company has the right to consideration for TSA services in an amount that corresponds directly with the value to Secura of the Company’s performance to date. Consideration allocated to the Secura TSA Services will be recognized as such services are provided over the performance period using an output method based on the amount to which the Company has a right to invoice. The Company determined $0.2 million of future potential royalties the Company expects to receive pursuant to the Secura APA were not constrained as of December 31, 2021. When estimating the amount of royalties to be received that were not constrained, the Company used the expected value method as there are a range of possible outcomes. When estimating royalties to be received, the Company used a combination of internal projections and forecasts and data from external sources. The Company determined that all other future potential royalties were constrained under the guidance as of December 31, 2021. As part of the Company’s evaluation of the constraint on future royalties, the Company considered a number of factors in determining whether there is significant uncertainty associated with the future events that would result in royalty payments. Those factors include: the likelihood and magnitude of revenue reversals related to future royalties, the amount of variable consideration is highly susceptible to factors outside of the Company’s influence, the amount of time to resolve the uncertainty, and lack of significant history of selling COPIKTRA outside of the United States. In addition, the Company has recognized less than $0.1 million of sale of COPIKTRA license and related assets revenue for royalties earned on sales that occurred during the year ended December 31, 2021. As the consideration for future royalties is conditional, the Company recorded a corresponding contract asset for the expected future royalties. Portions of the contract asset are reclassified to accounts receivable when the right to consideration becomes unconditional. As of December 31, 2021, the $0.2 million contract asset has been recorded within prepaid and other current assets on the consolidated balance sheet. The following table presents changes in the Company’s contract asset for the year ended December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: Balance at December 31, 2020 Additions ​ Reclassification to receivable ​ Balance at December 31, 2021 Contract asset - Secura ​ $ — ​ $ 197 ​ $ (27) ​ $ 170 Total $ — ​ $ 197 ​ $ (27) ​ $ 170 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During the year ended December 31, 2021, two regulatory milestones were achieved by Secura’s sublicensee, Sanofi, of which 50% of the milestone or $1.3 million was paid to the Company pursuant to the Secura APA. The Company determined all other future potential milestones were excluded from the transaction price, as all other milestone amounts were fully constrained under the guidance as of December 31, 2021. As part of the Company’s evaluation of the constraint, the Company considered a number of factors in determining whether there is significant uncertainty associated with the future events that would result in the milestone payments. Those factors include: the likelihood and magnitude of revenue reversals related to future milestones, the amount of variable consideration is highly susceptible to factors outside of the Company’s influence and the uncertainty about the consideration is not expected to be resolved for a long period of time. All other future potential milestone payments were fully constrained as the risk of significant revenue reversal related to these amounts has not yet been resolved. During the year ended December 31, 2021, the Company recognized $1.4 million of sale of COPIKTRA license and related assets revenue within the statements of operations and comprehensive loss. The sale of COPIKTRA license and related assets revenue for the year ended December 31, 2021 primarily related to two regulatory milestone for $1.3 million achieved by Secura’s sublicensee and $0.2 million related to royalties received and expected to be received pursuant to the Secura APA. During the year ended December 31, 2021, the Company also recognized $0.6 million in transition services revenue within the statements of operations and comprehensive loss. During the year ended December 31, 2020, the Company recognized $70.0 million as sale of COPIKTRA license and related assets revenue related to delivery of the Bundled Secura Performance Obligation and $0.4 million in transition services revenue within the statements of operations and comprehensive loss. The Company recognized approximately $31.2 million of cost of sales – sale of COPIKTRA license and related assets within the statements of operations and comprehensive loss which consisted of $19.2 million, $6.0 million, $5.8 million and $0.2 million for the intangible asset, certain duvelisib inventory, net duvelisib contract prepaid balances and manufacturing equipment, respectively, which were delivered to Secura as part of the sale. Chugai Pharmaceutical Co., Ltd (Chugai) On January 7, 2020, the Company entered into a license agreement with Chugai (the Chugai Agreement) whereby Chugai granted the Company an exclusive worldwide license for the development, commercialization and manufacture of products containing VS-6766, a dual RAF/MEK inhibitor. Under the terms of the Chugai Agreement, the Company received an exclusive right to develop and commercialize products containing VS-6766 at the Company’s own cost and expense. The Company is required to pay Chugai a non-refundable payment of $3.0 million which was paid in February 2020. The Company is further obligated to pay Chugai double-digit royalties on net sales of products containing VS-6766, subject to reduction in certain circumstances. Chugai also obtained opt back rights to develop and commercialize VS-6766 (a) in the European Union, which option may be exercised through the date the Company submits a NDA to the FDA for a product which contains VS-6766 as the sole active pharmaceutical ingredient and (b) in Japan and Taiwan, which option may be exercised through the date the Company receives marketing authorization from the FDA for a product which contains VS-6766 as the sole active pharmaceutical ingredient. As consideration for executing either option, Chugai would have to make a payment to the Company calculated on the Company’s development costs to date. Chugai and the Company have made customary representations and warranties and have agreed to certain customary covenants, including confidentiality and indemnification. Unless earlier terminated, the Chugai Agreement will expire upon the fulfillment of the Company’s royalty obligations to Chugai for the sale of any products containing the VS-6766, which royalty obligations expire on a product-by-product and country-by-country basis, upon the last to occur, in each specific country, of (a) expiration of valid patent claims covering such product or (b) 12 years from the first commercial sale of such product in such country. The Company may terminate the Chugai Agreement upon 180 days ’ written notice. Subject to certain limitations, Chugai may terminate the Chugai Agreement upon written notice if the Company challenges any patent licensed by Chugai to the Company under the Chugai Agreement. Either party may terminate the license agreement in its entirety with 120 days ’ written notice for the other party’s material breach if such party fails to cure the breach. Either party may also terminate the Chugai Agreement in its entirety upon certain insolvency events involving the other party. The Company evaluated the license agreement with Chugai under ASC Topic 805, Business Combinations ) combination and therefore was accounted for as an asset acquisition. The Company recorded the up-front payment of $3.0 million as research and development expense within the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020. Infinity Pharmaceuticals, Inc. (Infinity) In November 2016, the Company entered into the Infinity License Agreement with Infinity under which the Company acquired an exclusive worldwide license for the research, development, commercialization, and manufacture of products in oncology indications containing duvelisib. Pursuant to the terms of the Infinity License Agreement, the Company was obligated to pay Infinity royalties on worldwide net sales of any products in an oncology indication containing duvelisib ranging from the mid-single digits to the high single-digits. In addition to the foregoing, the Company was obligated to pay Infinity an additional royalty of 4% on worldwide net sales of any products in an oncology indication containing duvelisib to cover the reimbursement of research and development costs owed by Infinity to Mundipharma International Corporation Limited (MICL) and Purdue Pharmaceutical Products L.P. (Purdue). During the year ended December 31, 2021, 2020, and 2019, the Company recorded royalty expense of $0.0 million, $1.3 million, and $1.0 million, respectively related to the Infinity License Agreement, which are included in costs of sales - product within the consolidated statements of operation and comprehensive loss. As discussed above under heading Secura Bio, Inc. (Secura) Sanofi On July 25, 2019, the Company entered into a license and collaboration agreement with Sanofi (the Sanofi Agreement), under which the Company granted exclusive rights to Sanofi to develop and commercialize products containing duvelisib in Russia, the Commonwealth of Independent States (CIS), Turkey, the Middle East and Africa (collectively the “Sanofi Territory”) for the treatment, prevention, palliation or diagnosis of any oncology indication in humans or animals. Sanofi paid the Company an upfront, non-refundable payment of $5.0 million in August 2019. The Company is also entitled to receive aggregate payments of up to $42.0 million if certain regulatory and commercial milestones are successfully achieved. Sanofi is obligated to pay the Company double-digit royalties on net sales of products containing duvelisib in the Sanofi Territory, subject to reduction in certain circumstances. The Company satisfied the performance obligation upon delivery of the license and initial technology transfer and recognized the upfront payment of $5.0 million as license and collaboration revenue during the year ended December 31, 2019. For the year ended December 31, 2020, the Company recognized $2.5 million of license revenue upon achievement of two development milestones which were paid in the year ended December 31, 2020. As discussed above under heading Secura Bio, Inc. (Secura) Yakult Honsha Co., Ltd. (Yakult) On June 5, 2018, the Company entered into a license and collaboration agreement (the Yakult Agreement) with Yakult, under which the Company granted exclusive rights to Yakult to develop and commercialize products containing duvelisib in Japan for the treatment, prevention, palliation or diagnosis of all oncology indications in humans or animals. Yakult paid the Company an upfront, non-refundable payment of $10.0 million in June 2018. The Company is also entitled to receive aggregate payments of up to $90.0 million if certain development, regulatory and commercial milestones are successfully achieved. Yakult is obligated to pay the Company a double-digit royalty on net sales of products containing duvelisib in Japan, subject to reduction in certain circumstances, and to fund certain global development costs related to worldwide clinical trials conducted by the Company in which Yakult has opted to participate (Global Clinical Trials) on a pro-rata basis. As discussed above under heading Secura Bio, Inc. (Secura) Secura Bio, Inc. (Secura) CSPC Pharmaceutical Group Limited (CSPC) On September 25, 2018, the Company entered into a license and collaboration agreement with CSPC (the CSPC Agreement), under which the Company granted exclusive rights to CSPC to develop and commercialize products containing duvelisib in the People’s Republic of China (China), Hong Kong, Macau and Taiwan CSPC paid the Company an aggregate upfront, non-refundable payment of $15.0 million, less the previously paid $5.0 million Exclusivity Fee. The Company is also entitled to receive aggregate payments of up to $160.0 million if certain development, regulatory and commercial milestones are successfully achieved. CSPC is obligated to pay the Company a double-digit royalty on net sales of products containing duvelisib in the CSPC Territory Secura Bio, Inc. (Secura Secura Bio, Inc. (Secura)

Restructurings

Restructurings	12 Months Ended
	Dec. 31, 2021
Restructurings
Restructurings	15. Restructurings On October 28, 2019, the Company committed to an operational plan to reduce overall operating expenses, including the elimination of approximately 40 positions across the Company and other cost-saving measures (the October 2019 Restructuring). The October 2019 Restructuring was designed to streamline operations, speed execution, and reflect the focused, account-based approach in the field. The Company recorded $1.2 million of expense for the year ended December 31, 2019 for one-time termination benefits to the affected employees, including cash severance payments, healthcare benefits, and outplacement assistance. On February 27, 2020, following further analysis of the Company’s strategy, the Company committed to an operational plan to reduce overall operating expenses, including the elimination of approximately 31 positions across the Company and other cost-saving measures (the February 2020 Restructuring). The February 2020 Restructuring is designed to streamline operations, speed execution of the Company’s clinical development of VS-6766 and defactinib, and reflect a focused, account-based approach in the field. In August 2020, in connection with the duvelisib sale to Secura pursuant to the Secura APA, the Company committed to a strategic restructuring (the August 2020 Restructuring). The restructuring included a workforce reduction of approximately 41 positions primarily in the Company’s commercial operations department. During the year-ended December 31, 2020, the Company recorded an aggregate expense of $4.6 million for the February 2020 Restructuring and August 2020 Restructuring for one-time termination benefits for employee severance, benefits, and related costs. This expense is reflected in the consolidated statements of operation and comprehensive loss as selling general, and administrative expense for $4.1 million, and research and development expense for $0.5 million. There were no restructuring expenses for the year ended December 31, 2021. The following table summarizes the accrued liabilities activity recorded in connection with the restructurings for the year ended December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee severance, benefits and related costs Amounts accrued at December 31, 2020 Charges ​ Amount Paid ​ Adjustments ​ Amounts accrued at December 31, 2021 August 2020 Restructuring ​ ​ 1,027 ​ ​ — ​ ​ (1,027) ​ ​ — ​ ​ — Total $ 1,027 ​ $ — ​ $ (1,027) ​ $ — ​ $ — ​

Employee benefit plan

Employee benefit plan	12 Months Ended
	Dec. 31, 2021
Employee benefit plan
Employee benefit plan	16. Employee benefit plan In June 2011, the Company adopted a 401(k) retirement and savings plan (the 401(k) Plan) covering all employees. The 401(k) Plan allows employees to make pre-tax or post-tax contributions up to the maximum allowable amount set by the Internal Revenue Service. Under the 401(k) Plan, the Company may make discretionary contributions as approved by the board of directors. The Company made contributions to the 401(k) Plan of approximately $0.8 million, $0.9 million, and $1.3 million for the years ended December 31, 2021, 2020, and 2019, respectively.

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2021
Subsequent events.
Subsequent events	17. Subsequent events The Company reviews all activity subsequent to year end but prior to the issuance of the consolidated financial statements for events that could require disclosure or that could impact the carrying value of assets or liabilities as of the consolidated balance sheet date. The Company is not aware of any material subsequent events other than the following: Loan and Security Agreement Contemporaneously with executing the Loan Agreement, the Company drew down the first $25.0 million tranche (Term Loan A). The second, third and fourth tranches (Term Loan B, Term Loan C, and Term Loan D, respectively) may be drawn at the Company’s option upon the achievement of certain pre-determined milestones. The fifth tranche of $50.0 million (Term Loan E) will only be available at the sole discretion of the lender. The Company will be required to make a final payment of 5.0% of the original principal amount of the Term Loans that were drawn, payable at maturity or upon any earlier acceleration or prepayment of the Term Loans. The Company may prepay all, but not less than all, of the Term Loans, subject to a prepayment fee equal to (i) 3.0% of the principal amount of the applicable Term Loan if prepaid on or before the first anniversary date of the funding date of such Term Loan, (ii) 2.0% of the principal amount of the applicable Term Loan if prepaid after the first anniversary and on or before the second anniversary of the funding date of such Term Loan, and (iii) 1.0% of the principal amount of the applicable Term Loan if prepaid after the second anniversary of the applicable funding date of such Term Loan. All Term Loans will be subject to a facility fee of 0.5% of the principal amount. ​

Significant accounting polici_2

Significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2021
Significant accounting policies
Basis of presentation	Basis of presentation The accompanying financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) under the assumption that the Company will continue as a going concern for the next twelve months. Accordingly, they do not include any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern.
Use of estimates	Use of estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including estimates related to revenue recognition, including returns, rebates, and other pricing adjustments, accrued and prepaid clinical trial expense and other general accruals and stock-based compensation expense. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable. Actual results could differ from such estimates.
Segment and geographic information	Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available and regularly reviewed by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing drugs for the treatment of cancer. All material long-lived assets of the Company reside in the United States.
Cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist of a U.S. Government money market funds and corporate bonds and commercial paper of publicly traded companies. Cash equivalents are reported at fair value. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 December 31, 2020 Cash and cash equivalents ​ $ 21,252 ​ $ 67,782 Restricted cash ​ 241 ​ 241 Total cash, cash equivalents and restricted cash ​ $ 21,493 ​ $ 68,023 ​
Fair value of financial instruments	Fair value of financial instruments The Company determines the fair value of its financial instruments based upon the fair value hierarchy, which prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs: ​ ​ ​ ​ Level 1 inputs Quoted prices in active markets for identical assets or liabilities that the Company can access at the measurement date. Level 2 inputs ​ Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ​ Level 3 inputs ​ Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. ​ ​ Items Measured at Fair Value on a Recurring Basis The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 19,302 ​ $ 19,302 ​ $ — ​ $ — ​ Short-term investments ​ ​ 79,004 ​ ​ — ​ ​ 79,004 ​ ​ — ​ Total financial assets ​ $ 98,306 ​ $ 19,302 ​ $ 79,004 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 65,610 ​ $ 60,611 ​ $ 4,999 ​ $ — ​ Short-term investments ​ 73,444 ​ — ​ 73,444 ​ — ​ Long-term investments ​ ​ 5,995 ​ ​ — ​ ​ 5,995 ​ ​ — ​ Total financial assets ​ $ 145,049 ​ $ 60,611 ​ $ 84,438 ​ $ — ​ ​ confirming that the relevant markets are active. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of December 31, 2021 and 2020. Fair Value of Financial Instruments ​ Note 10. Convertible Senior Notes
Investments	Investments Investments and cash equivalents consist of investments in a U.S. Government money market funds, overnight repurchase agreements collateralized by government agency securities or U.S. Treasury securities, corporate bonds and commercial paper of publicly traded companies that are classified as available-for-sale pursuant to Accounting Standards Codification (ASC) Topic 320, Investments—Debt and Equity Securities . The Company classifies investments available to fund current operations as current assets on its consolidated balance sheets. Investments are carried at fair value with unrealized gains and losses included as a component of accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity, until such gains and losses are realized. The fair value of these securities is based on quoted prices for identical or similar assets. If a decline in the fair value is considered other-than-temporary, based on available evidence, the unrealized loss is transferred from other comprehensive loss to the consolidated statements of operations and comprehensive loss. The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers the intent to sell, or whether it is more likely than not that the Company will be required to sell, the investment before recovery of the investment’s amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to year end. Realized gains and losses are determined using the specific identification method and are included in interest income in the consolidated statements of operations and comprehensive loss. There were no realized gains or losses on investments for the years ended December 31, 2021, 2020 or 2019. There were three debt securities and one debt security in an unrealized loss position as of December 31, 2021 and December 31, 2020, respectively. None of these investments had been in an unrealized loss position for more than 12 months as of December 31, 2021, or December 31, 2020, respectively. The fair value of these securities as of December 31, 2021, and December 31, 2020, was $15.8 million and $6.0 million, respectively, and the aggregate unrealized loss was immaterial. The Company considered the decline in the market value for these securities to be primarily attributable to current economic conditions. As it was not more likely than not that the Company would be required to sell these securities before the recovery of their amortized cost basis, which may be at maturity, the Company did not consider these investments to be other-than-temporarily impaired as of December 31, 2021, and December 31, 2020, respectively. Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Total cash, cash equivalents & restricted cash: ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total investments ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 100,463 ​ $ 48 ​ $ (14) ​ $ 100,497 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 63,024 ​ $ — ​ $ — ​ $ 63,024 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 4,998 ​ $ 1 ​ $ — ​ $ 4,999 ​ Total cash, cash equivalents & restricted cash: ​ $ 68,022 ​ $ 1 ​ $ — ​ $ 68,023 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds and commercial paper (due within 1 year ) ​ $ 73,389 ​ $ 55 ​ $ — ​ $ 73,444 ​ Corporate bonds and commercial paper (due between 1 and 5 years ) ​ ​ 5,998 ​ ​ — ​ ​ (3) ​ ​ 5,995 ​ Total investments ​ $ 79,387 ​ $ 55 ​ $ (3) ​ $ 79,439 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 147,409 ​ $ 56 ​ $ (3) ​ $ 147,462 ​ ​
Concentrations of credit risk and off-balance sheet risk	Concentrations of credit risk and off-balance sheet risk Cash and cash equivalents, investments, and trade accounts receivable are financial instruments that potentially subject the Company to concentrations of credit risk. The Company mitigates this risk by maintaining its cash and cash equivalents and investments with high quality, accredited financial institutions. The management of the Company’s investments is not discretionary on the part of these financial institutions. As of December 31, 2021, the Company’s cash, cash equivalents and investments were deposited at three financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. As of December 31, 2021, and 2020, there was one customer, Secura, and two customers, respectively that cumulatively made up more than 50% of the Company’s trade accounts receivable balance. The Company assesses the creditworthiness of all its customers and sets and reassesses customer credit limits to ensure collectability of any trade accounts receivable balances are assured. For the year ended December 31, 2021 and 2020, one customer, Secura, individually accounted for greater than 10% of the Company’s total revenues.
Property and equipment	Property and equipment Property and equipment consist of laboratory equipment, office furniture, computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Depreciation and amortization are calculated using the straight-line method over the following estimated useful lives of the assets: ​ ​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​ ​ Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of assets may not be recoverable. Recoverability is measured by comparison of the asset’s book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded through December 31, 2021.
Research and development costs	Research and development costs The Company expenses research and development costs to operations as incurred. Research and development expenses consist of: ● employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; ● external research and development expenses incurred under arrangements with third parties, such as CROs, clinical trial sites, manufacturing organizations and consultants, including the scientific advisory board; ● license fees; ● facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation of equipment, and laboratory supplies; and
Stock-based compensation	Stock-based compensation For service-based equity awards, the Company recognizes stock-based compensation expense for stock options, and restricted stock units (RSUs) issued to employees, directors, and consultants based on the grant date fair value of the awards on a straight-line basis over the requisite service period, which typically is the vest period. The Company recognized stock-based compensation for shares issued to employees under the Company’s employee stock purchase plan (ESPP) plan. The Company has granted performance-based RSUs and stock options with terms that allow the recipients to vest in a specific number of shares based upon the achievement of performance-based milestones as specified in the grants. Stock-based compensation expense associated with these performance-based RSUs and stock options is recognized if the performance condition is considered probable of achievement using the Company’s best estimates of the time to vesting for the achievement of the performance-based milestones. based vesting requirements are expensed utilizing an accelerated attribution model if achievement of the performance criteria is determined to be probable. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model that takes into account the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company applies the simplified method described in the Securities and Exchange Commission (SEC) Staff Accounting Bulletin (SAB) Topic 14.D.2 to calculate the expected term as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted to employees. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its population. The Company has not paid and do not anticipate paying cash dividends on the Company’s shares of common stock; therefore, the expected dividend yield is assumed to be zero. The computation of expected volatility is based on the historical volatility of the Company’s common stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company accounts for forfeitures as they occur. The Company issues shares under the Company’s employee stock purchase plan (ESPP) to employees. Stock-based compensation expense for discounted purchases under the ESPP is measured using the Black-Scholes model to compute the fair value of the lookback provision plus the purchase discount and is recognized as compensation expense over the offering period
Leases	Leases Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances within the arrangement. A lease is identified where an arrangement conveys the right to control the use of identified property, plant, and equipment for a period of time in exchange for consideration. Leases which are identified within the scope of ASC 842 and which have a term greater than one year are recognized on the Company’s consolidated balance sheets as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. The Company has elected not to recognize leases with terms of one year or less on its consolidated balance sheets. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. However, certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rates to calculate the present value of lease payments. Incremental borrowing rates are the rates the Company incurs to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. In accordance with ASC 842, components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). The fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available. Entities may elect the practical expedient to not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company has elected to account for the lease and non-lease components of each of its operating leases as a single lease component and allocate all of the contract consideration to the lease component only. The lease component results in an operating right-of-use asset being recorded on the consolidated balance sheets and amortized on a straight-line basis as lease expense.
Revenue Recognition	Revenue Recognition Revenue from Contracts with Customers Product Revenue, Net Product Revenue, Net – The Company recognized revenue on sales of COPIKTRA when a customer obtains control of the product, which occurs at a point in time (typically upon delivery). Product revenues are recorded at the wholesale acquisition costs, net of applicable reserves for variable consideration. Components of variable consideration include trade discounts and allowances, Third-Party Payer chargebacks and discounts, government rebates, other incentives, such as voluntary co-pay assistance, product returns, and other allowances that are offered within contracts between the Company and customers, payors, and other indirect customers relating to the Company’s sale of COPIKTRA. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable or a current liability. These estimates take into consideration a range of possible outcomes based upon relevant factors such as customer contract terms, information received from third parties regarding the anticipated payor mix for COPIKTRA, known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled with respect to sales made. The amount of variable consideration which is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under contracts will not occur in a future period. The Company’s analyses contemplate the application of the constraint in accordance with ASC 606. For the years ended December 31, 2020 and 2019, the Company determined a material reversal of revenue would not occur in a future period for the estimates detailed below and, therefore, the transaction price was not reduced further. There was not any product revenue, net recorded for the year ended December 31, 2021. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Trade Discounts and Allowances: The Company generally provided customers with invoice discounts on sales of COPIKTRA for prompt payment, which are explicitly stated in the Company’s contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized. In addition, the Company compensated its specialty distributor customers for sales order management, data, and distribution services. The Company has determined such services are not distinct from the Company’s sale of COPIKTRA to the specialty distributor customers and, therefore, these payments have also been recorded as a reduction of revenue within the consolidated statements of operations and comprehensive loss for the years ended December 31, 2020 and 2019. There were no amounts recorded for the year ended December 31, 2021. Third-Party Payer Chargebacks, Discounts and Fees: The Company executed contracts with Third-Party Payers which allowed for eligible purchases of COPIKTRA at prices lower than the wholesale acquisition cost charged to customers who directly purchase the product from the Company. In some cases, customers charged the Company for the difference between what they paid for COPIKTRA and the ultimate selling price to the Third-Party Payers. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable, net. Chargeback amounts are generally determined at the time of resale to the qualified Third-Party Payer by customers, and the Company generally issues credits for such amounts within a few weeks of the customer’s notification to the Company of the resale. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at the end of each reporting period that the Company expects will be sold to Third-Party Payers, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. In addition, the Company compensated certain Third-Party Payers for administrative services, such as account management and data reporting. These administrative service fees have also been recorded as a reduction of product revenue within the consolidated statements of operations and comprehensive loss for the years ended December 31, 2020 and 2019. There were no amounts recorded for the year ended December 31, 2021. Government Rebates: The Company was subject to discount obligations under state Medicaid programs and Medicare. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses on the consolidated balance sheets. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom the Company will owe an additional liability under the Medicare Part D program. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel inventories at the end of each reporting period. Other Incentives: Other incentives which the Company offered include voluntary co-pay assistance programs, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive for product that has been recognized as revenue but remains in the distribution channel inventories at the end of each reporting period. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included as a component of accrued expenses on the consolidated balance sheets. Product Returns: Consistent with industry practice, the Company generally offers customers a limited right of return for product that has been purchased from the Company. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The Company estimates product return liabilities using available industry data and its own sales information, including its visibility into the inventory remaining in the distribution channel. Subject to certain limitations, the Company’s return policy allows for eligible returns of COPIKTRA for credit under the following circumstances: ● Receipt of damaged product; ● Shipment errors that were a result of an error by the Company; ● Expired product that is returned during the period beginning three months prior to the product’s expiration and ending six months after the expiration date; ● Product subject to a recall; and ● Product that the Company, at its sole discretion, has specified can be returned for credit. If taxes should be collected from customers relating to product sales and remitted to governmental authorities, they will be excluded from product revenue. The Company expenses incremental costs of obtaining a contract when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. Licenses and Sales of Intellectual Property Licenses of Intellectual Property - The Company may enter into collaboration and licensing arrangements for research and development, manufacturing, and commercialization activities with collaboration partners for the development and commercialization of its product candidates, which have components within the scope of ASC 606. The arrangements generally contain multiple elements or deliverables, which may include (i) licenses, or options to obtain licenses, to the Company’s intellectual property or sale of the Company’s license, (ii) research and development activities performed for the collaboration partner, (iii) participation on joint steering committees, and (iv) the manufacturing of commercial, clinical or preclinical material. Payments pursuant to these arrangements typically include non-refundable, upfront payments, milestone payments upon the achievement of significant development events, research and development reimbursements, sales milestones, and royalties on product sales. The amount of variable consideration is constrained until it is probable that the revenue is not at a significant risk of reversal in a future period. The contracts into which the Company enters generally do not include significant financing components. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its collaboration and license agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract within the scope of ASC 606; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: a) the number of performance obligations based on the determination under step (ii) above; b) the transaction price under step (iii) above; c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above; and d) the measure of progress in step (v) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties on license arrangements, should be included in the transaction price as described further below. If a license to the Company’s intellectual property is determined to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. In assessing whether a promise or performance obligation is distinct from the other elements, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of its associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a promise for its intended purpose without the receipt of the remaining elements, whether the value of the promise is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure as of progress of each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The measure of progress, and thereby periods over which revenue should be recognized, is subject to estimates by management and may change over the course of the arrangement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Customer Options: If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services such as research and development services or manufacturing services, the goods and services underlying the customer options are not considered to be performance obligations at the inception of the arrangement; rather, such goods and services are contingent on exercise of the option, and the associated option fees are not included in the transaction price. The Company evaluates customer options for material rights or options to acquire additional goods or services for free or at a discount. If a customer option is determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the estimated probability that the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone Payments: At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the respective milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Royalties: For license arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. For sales of license and intellectual property, that include sale-based royalties, including milestone payments based on a level of sales, the Company evaluates whether the royalties and sales-based milestones are considered probable of being achieved and estimates the amount of royalties to include over the contractual term using the expected value method and estimates the sales-based milestones using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated royalty and milestone value is included in the transaction price. Royalties and sales-based milestones for territories for which there is not regulatory approval are not considered probable until such regulatory approval is achieved. The Company evaluates factors such as whether consideration is outside of the Company’s control, timeline for when the uncertainty will be resolved and historical sales of COPIKTRA if applicable. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and amount of royalty revenue to be received and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.
Collaborative Arrangements	Collaborative Arrangements Collaborative Arrangements: Contracts are considered to be collaborative arrangements when they satisfy the following criteria defined in ASC Topic 808, Collaborative Arrangements
Accounts Receivable, Net	Accounts Receivable, Net Accounts receivable, net consists of amounts due from customers, net of applicable revenue reserves. Accounts receivable have standard payments that generally require payment within 30 to 90 days . The Company analyzes accounts that are past due for collectability and provides an allowance for receivables when collection becomes doubtful. Given the nature and credit profile of the Company’s limited number of customers, an allowance for doubtful accounts is not deemed necessary at December 31, 2021.
Income taxes	Income taxes The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. The Company recognizes the tax effects of an uncertain tax position only if it is more likely than not that it will be sustained based solely on its technical merits as of the reporting date and only in an amount more likely than not that it will be sustained upon review by the tax authorities. The Company evaluates uncertain tax positions on a quarterly basis and adjust the liability for changes in facts and circumstances, such as new regulations or interpretations by the taxing authorities, new information obtained during a tax examination, significant amendment to an existing tax law, or resolution of an examination. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will impact the income tax provision in the period in which such determination is made. The resolution of its uncertain income tax positions is dependent on uncontrollable factors such as law changes, new case law, and the willingness of the income tax authorities to settle, including the timing thereof and other factors. Although the Company does not anticipate significant changes to its uncertain income tax positions in the next twelve months, items outside of its control could cause its uncertain income tax positions to change in the future, which would be recorded in its statements of operations. Interest and/or penalties related to income tax matters are recognized as a component of income tax expense. Net operating loss (NOL) and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company experienced a greater than 50% change in ownership as defined under Section 382 and 383 of the Internal Revenue Code as well as similar state provisions during the year ended December 31, 2020. For more details please refer to Note 12. Income Taxes.
Net loss per share	Net loss per share Basic net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net loss per common share is calculated by increasing the denominator by the weighted-average number of additional shares that could have been outstanding from securities convertible into common stock, such as stock options, restricted stock units and warrants (using the “treasury stock” method) and Notes (using the “if-converted” method), unless their effect on net loss per share is antidilutive. The effect of computing diluted net loss per common share was antidilutive for any potentially issuable shares of common stock from the conversion of stock options, restricted stock units and warrants and, as such, have been excluded from the calculation. However, under the “if-converted” method, convertible instruments that are-in-the-money, are assumed to have been converted as of the beginning of the period or when issued, if later. Additionally, the effects of any interest expense and changes in fair value of bifurcated derivatives shall be added back to the numerator of the diluted net loss per share calculation. Refer to Note 11, Net Loss per share
Recently Adopted and/or Issued Accounting Standards Updates	Recently Issued Accounting Standards Updates In June 2016, the FASB issued Accounting Standard Update (ASU) No. 2016-13, Measurement of Credit Losses on Financial Instruments (ASU 2016-13). ASU 2016-13 will replace the incurred loss impairment methodology under current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives (Topic 815), and Leases (Topic 842). This ASU delayed the required adoption for SEC filers that are smaller reporting companies as of their determination on November 15, 2019, until annual and interim periods beginning after December 15, 2022, with early adoption permitted. The Company has determined that as of November 15, 2019, it is a smaller reporting company and has not elected to early adopt this standard. The Company is currently evaluating the impact the adoption of the standard will have on its consolidated financial statements and related disclosures. In August 2020, the FASB issued No. ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815 – 40) (ASU 2020-06). ASU 2020-06 simplifies the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. More specifically, the amendments focus on the guidance for convertible instruments and derivative scope exception for contracts in an entity’s own equity. The ASU also simplifies the diluted earnings per share (EPS) calculation in certain areas. For smaller reporting companies, ASU 2020-06 is effective for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years. The Company is currently evaluating the impact ASU 2020-06 will have on its consolidated financial statements and related disclosures. Recently Adopted Accounting Standards Updates In December 2019, the FASB issued Accounting Standard Update (ASU) No 2019-12, Simplifying Accounting for Income Taxes (ASU 2019-12). ASU 2019-12 removes certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocations, calculating income taxes in interim periods, and adds certain guidance to remove complexity in certain areas. ASU 2019-12 is effective for all entities for annual and interim periods beginning after December 15, 2020. In the first quarter of 2021, the Company adopted ASU 2019-12. The provisions related to intraperiod tax allocation and interim recognition of enactment of tax laws are being adopted on a prospective basis. The adoption of ASU 2019-12 did not have an effect on the Company’s consolidated financial statements or disclosures.

Significant accounting polici_3

Significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2021
Significant accounting policies
Schedule of reconciliation of cash, cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 December 31, 2020 Cash and cash equivalents ​ $ 21,252 ​ $ 67,782 Restricted cash ​ 241 ​ 241 Total cash, cash equivalents and restricted cash ​ $ 21,493 ​ $ 68,023
Schedule of financial instruments measured at fair value on a recurring basis	The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 19,302 ​ $ 19,302 ​ $ — ​ $ — ​ Short-term investments ​ ​ 79,004 ​ ​ — ​ ​ 79,004 ​ ​ — ​ Total financial assets ​ $ 98,306 ​ $ 19,302 ​ $ 79,004 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 65,610 ​ $ 60,611 ​ $ 4,999 ​ $ — ​ Short-term investments ​ 73,444 ​ — ​ 73,444 ​ — ​ Long-term investments ​ ​ 5,995 ​ ​ — ​ ​ 5,995 ​ ​ — ​ Total financial assets ​ $ 145,049 ​ $ 60,611 ​ $ 84,438 ​ $ — ​
Schedule of cash, cash equivalents and investments	Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Total cash, cash equivalents & restricted cash: ​ $ 21,493 ​ $ — ​ $ — ​ $ 21,493 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total investments ​ $ 78,970 ​ $ 48 ​ $ (14) ​ $ 79,004 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 100,463 ​ $ 48 ​ $ (14) ​ $ 100,497 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 63,024 ​ $ — ​ $ — ​ $ 63,024 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 4,998 ​ $ 1 ​ $ — ​ $ 4,999 ​ Total cash, cash equivalents & restricted cash: ​ $ 68,022 ​ $ 1 ​ $ — ​ $ 68,023 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds and commercial paper (due within 1 year ) ​ $ 73,389 ​ $ 55 ​ $ — ​ $ 73,444 ​ Corporate bonds and commercial paper (due between 1 and 5 years ) ​ ​ 5,998 ​ ​ — ​ ​ (3) ​ ​ 5,995 ​ Total investments ​ $ 79,387 ​ $ 55 ​ $ (3) ​ $ 79,439 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 147,409 ​ $ 56 ​ $ (3) ​ $ 147,462 ​
Schedule of estimated useful lives of the assets	​ ​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​

Property and equipment, net (Ta

Property and equipment, net (Tables)	12 Months Ended
	Dec. 31, 2021
Property and equipment, net
Schedule of property equipment and related accumulated depreciation	Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2021 ​ 2020 Leasehold improvements ​ $ 146 ​ $ 146 ​ Furniture and fixtures ​ 1,074 ​ 1,074 ​ Computer equipment ​ 665 ​ 665 ​ ​ ​ 1,885 ​ 1,885 ​ Less: accumulated depreciation ​ (1,675) ​ (1,469) ​ Total property and equipment, net ​ $ 210 ​ $ 416 ​

Accrued expenses (Tables)

Accrued expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Accrued expenses
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 December 31, 2020 Research and development expenses ​ $ 9,311 ​ $ 5,176 ​ Compensation and related benefits ​ 3,892 ​ 5,930 ​ Professional fees ​ 785 ​ 615 ​ Consulting fees ​ 544 ​ 1,091 ​ Interest ​ ​ 3 ​ ​ 236 ​ Commercialization costs ​ 187 ​ 330 ​ Other ​ 899 ​ 1,282 ​ Total accrued expenses ​ $ 15,621 ​ $ 14,660 ​

Product revenue reserves and _2

Product revenue reserves and allowances (Tables)	12 Months Ended
	Dec. 31, 2021
Product revenue reserves and allowances
Schedule of product revenue allowance and reserve categories	From September 24, 2018 (the date of the Company’s U.S. commercial launch of COPIKTRA) through September 30, 2020 (the date the Company sold COPIKTRA to Secura), the Company’s sole source of product revenue was from the gross sales of COPIKTRA in the United States less provisions for product sales allowances and accruals. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade ​ Payer ​ Government ​ ​ ​ ​ ​ ​ ​ ​ discounts ​ chargebacks, ​ rebates and ​ ​ ​ ​ ​ ​ ​ ​ and ​ discounts ​ other ​ ​ ​ ​ ​ ​ ​ allowances and fees incentives Returns Total Balance at December 31, 2019 ​ $ 111 ​ $ 255 ​ $ 372 ​ $ 76 ​ $ 814 Provision related to sales in the current year ​ ​ 640 ​ ​ 1,820 ​ ​ 609 ​ ​ 307 ​ ​ 3,376 Adjustments related to prior period sales ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — Credits and payments made ​ ​ (728) ​ ​ (2,075) ​ ​ (914) ​ ​ (352) ​ ​ (4,069) Balance at December 31, 2020 ​ $ 23 ​ $ — ​ $ 67 ​ $ 31 ​ $ 121 Provision related to sales in the current year ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Adjustments related to prior period sales ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Credits and payments made ​ (23) ​ ​ — ​ ​ (67) ​ ​ (31) ​ (121) Ending balance at December 31, 2021 ​ $ — ​ $ — ​ $ — ​ $ — ​ $ —

Lease (Tables)

Lease (Tables)	12 Months Ended
	Dec. 31, 2021
Leases
Summary of elements of lease expenses	The elements of lease expense were as follows (dollar amounts in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ ​ 2021 ​ 2020 Lease Expense ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ ​ $ 885 ​ $ 885 Total Lease Expense ​ ​ $ 885 ​ $ 885 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ ​ $ 1,019 ​ $ 955 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ 3.5 Weighted average discount rate ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ 2022 ​ ​ ​ ​ ​ ​ 1,039 2023 ​ ​ ​ ​ ​ ​ 1,060 2024 ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ ​ $ 3,726 Less: Present value discount ​ ​ ​ ​ ​ ​ (795) Lease Liability ​ ​ ​ ​ ​ $ 2,931

Common stock (Tables)

Common stock (Tables)	12 Months Ended
	Dec. 31, 2021
Common stock.
Schedule of shares of common stock reserved for the issuance of common stock for vested restricted stock units and the exercise of stock options	As of December 31, 2021 and 2020, the Company had reserved the following shares of common stock for the issuance of common stock for vested restricted stock units, the exercise of stock options, employee stock purchase plan and Notes conversions to shares of common stock (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2021 ​ 2020 Shares reserved under equity compensation plans 36,234 25,114 ​ Shares reserved for inducement grants ​ 3,991 ​ 4,058 ​ Shares reserved for 2018 Notes ​ 42 ​ 42 ​ Shares reserved for 2020 Notes ​ — ​ 8,615 ​ Employee Stock Purchase Plan ​ 1,190 ​ 1,300 ​ Total shares reserved 41,457 39,129 ​

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Stock-based compensation
Schedule of stock-based compensation expense as reflected in the Company's consolidated statements of operations and comprehensive loss	Stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 2020 2019 Research and development ​ $ 2,099 ​ $ 1,935 ​ $ 1,501 ​ Selling, general and administrative ​ 5,612 ​ 6,183 ​ 7,038 ​ Total stock-based compensation expense ​ $ 7,711 ​ $ 8,118 ​ $ 8,539 ​
Summary of stock option activity and related information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average exercise price per share Weighted-average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2020 12,690,745 ​ $ 3.90 6.5 ​ $ 3,390 ​ Granted 4,990,731 ​ ​ 2.50 ​ ​ ​ ​ ​ ​ Exercised (572,086) ​ ​ 1.58 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (845,292) ​ ​ 3.71 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2021 16,264,098 ​ $ 3.56 6.7 ​ $ 2,601 ​ Vested at December 31, 2021 9,218,745 ​ $ 4.38 4.9 ​ $ 2,150 ​
Schedule of assumptions used to estimate fair value of each stock option on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 ​ 2020 ​ 2019 Risk-free interest rate 1.15 % ​ 0.60 % ​ 1.98 % Volatility 89 % ​ 96 % ​ 87 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 6.0 ​ ​ 6.0 ​ ​ 5.9 ​
Schedule of restricted stock units	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average grant date fair value per share Outstanding at December 31, 2020 ​ 2,649,317 ​ $ 1.73 ​ Granted ​ 2,629,312 ​ $ 2.46 ​ Vested ​ (2,204,485) ​ $ 1.66 ​ Forfeited/cancelled ​ ​ (269,140) ​ $ 2.11 ​ Outstanding at December 31, 2021 ​ 2,805,004 ​ $ 2.44 ​
Schedule of assumptions used to estimate fair value of each employee stock purchase plan on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ ​ 2021 ​ 2020 ​ 2019 Risk-free interest rate 0.07 % ​ 1.04 % ​ 2.26 % Volatility 68 % ​ 109 % ​ 88 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​ ​ 0.5 ​

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Net Loss per Share
Schedule of potentially anti-dilutive securities excluded from calculation of diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 2019 Outstanding stock options ​ 16,264,098 12,690,745 17,258,524 ​ Outstanding restricted stock units ​ 2,805,004 ​ 2,649,317 ​ 678,089 ​ 2018 Notes ​ 41,873 ​ 41,873 ​ 3,950,032 ​ 2019 Notes ​ — ​ — ​ 34,796,363 ​ 2020 Notes ​ — ​ 8,615,384 ​ — ​ Employee stock purchase plan ​ 57,636 ​ 53,372 ​ 227,141 ​ Total potentially dilutive securities ​ 19,168,611 24,050,691 56,910,149 ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income taxes
Schedule of components of Income tax expense	For the years ended December 31, 2021, 2020, and 2019 income tax expense consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2021 2020 2019 Current tax expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ — ​ $ — ​ $ — State ​ — ​ 194 ​ — Current income tax expense ​ ​ — ​ ​ 194 ​ ​ — Deferred ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ — ​ ​ — ​ ​ — State ​ — ​ — ​ ​ — Deferred income tax expense ​ ​ — ​ ​ — ​ ​ — Total income tax expense $ — ​ $ 194 ​ $ —
Schedule of reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2021 2020 Income tax benefit using U.S. federal statutory rate 21.00 % 21.00 % State tax benefit, net of federal benefit 3.01 % (8.55) % Research and development tax credits 2.71 % 2.84 % Permanent items (0.44) % (0.60) % Change in the valuation allowance (21.23) % 35.09 % NOL and tax credit expiration under Section 382 ​ (4.34) % (52.67) % Other (0.71) % 2.60 % ​ — % (0.29) %
Schedule of principal components of deferred tax assets and liabilities	​ The principal components of the Company’s deferred tax assets and liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2021 2020 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 98,777 ​ $ 86,665 ​ Capitalized research and development ​ 1,276 ​ 1,565 ​ Research and development credits ​ 4,516 ​ 2,043 ​ Stock-based compensation ​ 4,200 ​ 4,041 ​ Installment sale ​ ​ 8,819 ​ ​ 9,981 ​ Lease liability ​ ​ 730 ​ ​ 950 ​ Other deferred tax assets ​ 411 ​ 680 ​ Total deferred tax assets ​ 118,729 ​ 105,925 ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Right-of-use asset ​ ​ (574) ​ ​ (742) ​ Debt discount ​ ​ (11) ​ ​ (2,245) ​ Other deferred tax liability ​ ​ (91) ​ ​ — ​ Total deferred tax liabilities ​ ​ (676) ​ ​ (2,987) ​ Net deferred tax asset prior to valuation allowance ​ ​ 118,053 ​ ​ 102,938 ​ Valuation allowance ​ (118,053) ​ (102,938) ​ Net deferred tax asset ​ $ — ​ $ — ​

License, collaboration and co_2

License, collaboration and commercial agreements (Tables)	12 Months Ended
	Dec. 31, 2021
License, collaboration and commercial agreements
Schedule of contract assets	The following table presents changes in the Company’s contract asset for the year ended December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: Balance at December 31, 2020 Additions ​ Reclassification to receivable ​ Balance at December 31, 2021 Contract asset - Secura ​ $ — ​ $ 197 ​ $ (27) ​ $ 170 Total $ — ​ $ 197 ​ $ (27) ​ $ 170 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Restructurings (Tables)

Restructurings (Tables)	12 Months Ended
	Dec. 31, 2021
Restructurings
Schedule of accrued restructuring liabilities	The following table summarizes the accrued liabilities activity recorded in connection with the restructurings for the year ended December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee severance, benefits and related costs Amounts accrued at December 31, 2020 Charges ​ Amount Paid ​ Adjustments ​ Amounts accrued at December 31, 2021 August 2020 Restructuring ​ ​ 1,027 ​ ​ — ​ ​ (1,027) ​ ​ — ​ ​ — Total $ 1,027 ​ $ — ​ $ (1,027) ​ $ — ​ $ —

Nature of business (Details)

Nature of business (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Nature of business
Cash, cash equivalents, restricted cash and investments	$ 100,300
Accumulated deficit	$ 663,711	$ 592,511

Significant accounting polici_4

Significant accounting policies - Segment and geographic information (Details)	12 Months Ended
	Dec. 31, 2021item
Segment and geographic information
Number of operating segments	1

Significant accounting polici_5

Significant accounting policies - Cash, cash equivalents and restricted cash - Security deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Cash and cash equivalents	$ 21,252	$ 67,782
Restricted cash	241	241
Total cash, cash equivalents and restricted cash	21,493	68,023	$ 79,262	$ 130,608
Letter of credit | Office and Laboratory Space in Needham, Massachusetts
Property, Plant and Equipment [Line Items]
Restricted cash	$ 200	$ 200

Significant accounting polici_6

Significant accounting policies - Fair Value Financial Instruments, Measured at Fair Value (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financial assets
Cash equivalents	$ 19,302	$ 65,610
Short-term investments	79,004	73,444
Long-term investments		5,995
Total financial assets	98,306	145,049
Quoted prices in active markets (Level 1)
Financial assets
Cash equivalents	19,302	60,611
Total financial assets	19,302	60,611
Significant other observable inputs (Level 2)
Financial assets
Cash equivalents		4,999
Short-term investments	79,004	73,444
Long-term investments		5,995
Total financial assets	$ 79,004	$ 84,438

Significant accounting polici_7

Significant accounting policies - Fair Value Financial Instruments, Derivative Liability (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Nov. 06, 2020	Oct. 17, 2018
5.00% Convertible Senior Notes due 2048
Derivative liability
Interest rate (as a percent)	5.00%	5.00%		5.00%
5.00% Convertible Senior Notes due 2048 | Significant unobservable inputs (Level 3)
Derivative liability
Debt, fair value	$ 0.3	$ 0.3
Debt, carrying value	$ 0.2	19.1
5.00% Convertible Senior Third Lien Notes due 2048
Derivative liability
Interest rate (as a percent)			5.00%
5.00% Convertible Senior Third Lien Notes due 2048 | Significant unobservable inputs (Level 3)
Derivative liability
Debt, carrying value		$ 30

Significant accounting polici_8

Significant accounting policies - Investments (Details)	12 Months Ended
	Dec. 31, 2021USD ($)item	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)
Investments
Cash, cash equivalents & restricted cash	$ 21,252,000	$ 67,782,000
Gross Unrealized Gains		1,000
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Gains	48,000	56,000
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Losses	(14,000)	(3,000)
Total cash, cash equivalents, restricted cash and investments, Fair Value	100,300,000
Realized gains or losses on investments	$ 0	$ 0	$ 0
Number of investments in unrealized loss position | item	3	1
Number of investments in unrealized loss position for more than 12 months	0	0
Unrealized loss on fair value	$ 15,800,000	$ 6,000,000
Amortized Cost
Investments
Total cash, cash equivalents, restricted cash and investments, Amortized Cost	100,463,000	147,409,000
Total
Investments
Total cash, cash equivalents, restricted cash and investments, Fair Value	100,497,000	147,462,000
Cash and money market accounts | Amortized Cost
Investments
Cash, cash equivalents & restricted cash	21,493,000	68,022,000
Cash and money market accounts | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value	21,493,000	68,023,000
Cash and money market accounts. | Amortized Cost
Investments
Cash, cash equivalents & restricted cash	21,493,000	63,024,000
Cash and money market accounts. | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value	21,493,000	$ 63,024,000
Corporate bonds, agency bonds and commercial paper
Investments
Original maturity period, cash and cash equivalents		90 days
Gross Unrealized Gains		$ 1,000
Corporate bonds, agency bonds and commercial paper | Amortized Cost
Investments
Cash, cash equivalents & restricted cash		4,998,000
Corporate bonds, agency bonds and commercial paper | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value		4,999,000
Investments.
Investments
Gross Unrealized Gains	48,000	55,000
Gross Unrealized Losses	(14,000)	(3,000)
Investments. | Amortized Cost
Investments
Investments, Amortize Cost	78,970,000	79,387,000
Investments. | Total
Investments
Investments, Fair Value	$ 79,004,000	$ 79,439,000
Corporate bonds, agency bonds and commercial paper (due within 1 year)
Investments
Maturity period, investments	1 year	1 year
Gross Unrealized Gains	$ 48,000	$ 55,000
Gross Unrealized Losses	(14,000)
Corporate bonds, agency bonds and commercial paper (due within 1 year) | Amortized Cost
Investments
Due within 1 year	78,970,000	73,389,000
Corporate bonds, agency bonds and commercial paper (due within 1 year) | Total
Investments
Due within 1 year, Fair Value	$ 79,004,000	73,444,000
Corporate bonds and commercial paper (due between 1 and 5 years)
Investments
Gross Unrealized Losses		(3,000)
Corporate bonds and commercial paper (due between 1 and 5 years) | Amortized Cost
Investments
Due between 1 and 5 years, Amortized Cost		5,998,000
Corporate bonds and commercial paper (due between 1 and 5 years) | Total
Investments
Due between 1 and 5 years, Fair Value		$ 5,995,000
Corporate bonds and commercial paper (due between 1 and 5 years) | Minimum
Investments
Maturity period, investments		1 year
Corporate bonds and commercial paper (due between 1 and 5 years) | Maximum
Investments
Maturity period, investments		5 years

Significant accounting polici_9

Significant accounting policies - Concentration of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2021customerInstitution	Dec. 31, 2020customer
Concentrations of credit risk and off-balance sheet risk
Off-balance sheet concentrations of credit risk description	As of December 31, 2021, the Company’s cash, cash equivalents and investments were deposited at three financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Number of financial institutions in which cash, cash equivalents and investments were deposited | Institution	3
Trade accounts receivable | Credit Concentration Risk
Concentrations of credit risk and off-balance sheet risk
Number of customer	1	2
Trade accounts receivable | Credit Concentration Risk | Minimum
Concentrations of credit risk and off-balance sheet risk
Percentage	50.00%	50.00%
Revenue | Customer Concentration Risk
Concentrations of credit risk and off-balance sheet risk
Number of customer	1	1
Revenue | Customer Concentration Risk | Minimum
Concentrations of credit risk and off-balance sheet risk
Percentage	10.00%	10.00%

Significant accounting polic_10

Significant accounting policies - Property and Equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Property and equipment, net
Impairment losses on long-lived assets	$ 0
Laboratory equipment
Property and equipment, net
Estimated useful lives	5 years
Furniture
Property and equipment, net
Estimated useful lives	5 years
Computer equipment
Property and equipment, net
Estimated useful lives	3 years

Significant accounting polic_11

Significant accounting policies - Revenue Recognition and Accounts Receivable, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue recognition
Total revenue	$ 2,053	$ 88,516	$ 17,456
Product revenue reserves and allowances		121	814
Cost Of Sale, License And Related Assets		31,187
Trade discounts and allowances
Revenue recognition
Product revenue reserves and allowances	0	23	111
Payer chargebacks,discounts and fees
Revenue recognition
Product revenue reserves and allowances			255
Government rebates and other incentives
Revenue recognition
Product revenue reserves and allowances	0	67	372
Returns
Revenue recognition
Product revenue reserves and allowances		31	$ 76
Copiktra license and related assets
Revenue recognition
Total revenue	1,447	$ 70,000
Product revenue reserves and allowances	$ 0
Minimum
Accounts Receivable
Threshold accounts receivable typically due	30 days
Maximum
Accounts Receivable
Threshold accounts receivable typically due	90 days
Prior to product's expiration
Revenue recognition
Period for eligible returns of expired product	3 months
After product's expiration date
Revenue recognition
Period for eligible returns of expired product	6 months

Property and equipment, net (De

Property and equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property and equipment
Property and equipment, gross	$ 1,885	$ 1,885
Less: accumulated depreciation	(1,675)	(1,469)
Property and equipment, net	210	416
Depreciation expenses	206	531	$ 429
Leasehold improvements
Property and equipment
Property and equipment, gross	146	146
Furniture
Property and equipment
Property and equipment, gross	1,074	1,074
Computer equipment
Property and equipment
Property and equipment, gross	$ 665	$ 665

Accrued expenses (Details)

Accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued expenses
Research and development expenses	$ 9,311	$ 5,176
Compensation and related benefits	3,892	5,930
Professional fees	785	615
Consulting fees	544	1,091
Interest	3	236
Commercialization costs	187	330
Other	899	1,282
Total accrued expenses	$ 15,621	$ 14,660

Long-term debt - Hercules term

Long-term debt - Hercules term loan facility (Details) - USD ($) $ in Thousands	Nov. 09, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Nov. 14, 2019	Mar. 21, 2017
Long-term debt
Amount drawn		$ 1,087	$ 2,985	$ 569
Loss on debt extinguishment			(1,580)
Amended Term Loan Agreement
Long-term debt
Repayment of term loan	$ 37,400
Repayment of principal	35,000
Repayment of final payment	1,800
Prepayment penalty fee	500
Accrued and unpaid interest	100
Loss on debt extinguishment			$ 1,600
Carrying amount of the debt excluding accrued interest	$ 1,600
Medium-term Notes [Member] | Original Loan Agreement
Long-term debt
Maximum borrowing capacity						$ 25,000
Medium-term Notes [Member] | Amended Term Loan Agreement
Long-term debt
Maximum borrowing capacity					$ 75,000

Product revenue reserves and _3

Product revenue reserves and allowances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	$ 121	$ 814
Provision related to sales in the current year		3,376
Credits and payments made	(121)	(4,069)
Product revenue reserves and allowances at ending		121
Trade discounts and allowances
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	23	111
Provision related to sales in the current year		640
Credits and payments made	(23)	(728)
Product revenue reserves and allowances at ending	0	23
Payer chargebacks,discounts and fees
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning		255
Provision related to sales in the current year		1,820
Credits and payments made		(2,075)
Government rebates and other incentives
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	67	372
Provision related to sales in the current year		609
Credits and payments made	(67)	(914)
Product revenue reserves and allowances at ending	0	67
Returns
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	31	76
Provision related to sales in the current year		307
Credits and payments made	$ (31)	(352)
Product revenue reserves and allowances at ending		$ 31

Leases - Leases (Details)

Leases - Leases (Details) - Office and Laboratory Space in Needham, Massachusetts	Feb. 15, 2018USD ($)ft²	Apr. 15, 2014ft²
Leases
Area of space | ft²	27,810	15,197
Minimum
Leases
Operating lease expense	$ 660,000
Maximum
Leases
Operating lease expense	$ 1,100,000

Leases - Balance sheet and othe

Leases - Balance sheet and other information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases
Right-of use asset	$ 2,302	$ 2,726
Lease liability	2,931
Lease Expense
Operating lease expense	885	885
Total Lease Expense	885	885
Other Information - Operating Leases
Operating cash flows paid for amounts included in measurement of lease liabilities	$ 1,019	$ 955
Weighted average remaining lease term (in years)	3 years 6 months
Weighted average discount rate	14.60%
Maturity Analysis
2022	$ 1,039
2023	1,060
2024	1,081
2025	546
Total	3,726
Less: Present value discount	(795)
Lease Liability	$ 2,931

Common stock (Details)

Common stock (Details) $ / shares in Units, $ in Thousands	Mar. 03, 2020USD ($)	Feb. 27, 2020$ / sharesshares	Aug. 28, 2017USD ($)	Mar. 30, 2017USD ($)	Aug. 31, 2021USD ($)	Dec. 31, 2021USD ($)Voteshares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)	Dec. 18, 2018shares
Common stock
Shares reserved for issuance						41,457,000	39,129,000
Number of votes entitled for each share of common stock | Vote						1
Common stock
Proceeds from Issuance of Common Stock | $						$ 6,723	$ 106,059
Private Investment in Public Equity (PIPE)
Common stock
Shares issued (in shares)		46,511,628
Proceeds from Issuance of Common Stock | $	$ 93,800
Share price (in dollars per share) | $ / shares		$ 2.15
Share price premium (as percentage)		12.60%
Share price, prior to premium price (in dollars per share) | $ / shares		$ 1.91
Common stock
Common stock
Shares issued (in shares)							46,511,628
Common stock | At-the-market equity offering program
Common stock
Shares issued (in shares)						0	6,769,559
Proceeds from Issuance of Common Stock | $							$ 12,200
Shares, Outstanding						18,287,913
Net proceeds from issuance of stock | $						$ 59,600
2017 ATM Program | Common stock | At-the-market equity offering program
Common stock
Maximum value of common stock allowed to be sold | $			$ 75,000	$ 35,000
Inducement Award Program
Common stock
Shares reserved for issuance						3,991,000	4,058,000
2021 ATM Program | At-the-market equity offering program
Common stock
Shares issued (in shares)						2,930,585
Net proceeds from issuance of stock | $						$ 6,800
2021 ATM Program | Common stock | At-the-market equity offering program
Common stock
Maximum value of common stock allowed to be sold | $					$ 100,000
Convertible Common Stock [Member] | 5.00% Convertible Senior Notes due 2048
Common stock
Shares reserved for issuance						42,000	42,000
Convertible Common Stock [Member] | 5.00% Convertible Senior Third Lien Notes due 2048
Common stock
Shares reserved for issuance							8,615,000
Equity compensation plans
Common stock
Shares reserved for issuance						36,234,000	25,114,000
Employee Stock purchase plan
Common stock
Shares reserved for issuance						1,190,000	1,300,000		2,000,000
Common stock
Proceeds from Issuance of Common Stock | $						$ 200	$ 400	$ 400

Stock-based compensation - Stoc

Stock-based compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Total stock-based compensation expense	$ 7,711	$ 8,118	$ 8,539
Research and development
Stock-based compensation
Total stock-based compensation expense	2,099	1,935	1,501
Selling, General And Administrative Expense [Member]
Stock-based compensation
Total stock-based compensation expense	$ 5,612	$ 6,183	$ 7,038

Stock-based compensation - Equi

Stock-based compensation - Equity Plans and Activity (Details)

Jan. 01, 2018shares

Jan. 01, 2017shares

Jan. 01, 2016shares

Feb. 29, 2020shares

Dec. 31, 2018shares

Jun. 30, 2018shares

Dec. 31, 2017shares

Dec. 31, 2016shares

Feb. 29, 2012shares

Dec. 31, 2021itemshares

Dec. 31, 2018shares

May 19, 2020shares

Dec. 18, 2018shares

Dec. 31, 2014shares

Stock-based compensation

Number of Equity Compensation Plans | item

2

Outstanding stock options

Stock-based compensation

Granted (in shares)

4,990,731

Exercised (in shares)

572,086

RSUs

Stock-based compensation

Granted (in shares)

2,629,312

Forfeited (in shares)

269,140

Vested (in shares)

2,204,485

Inducement Award Program

Stock-based compensation

Number of shares reserved

750,000

Additional number of shares authorized for issuance

1,250,000

1,700,000

2,500,000

580,000

Shares available for future grants

2,285,421

Reduction of shares available for issuance

2,033,367

Inducement Award Program | Outstanding stock options

Stock-based compensation

Granted (in shares)

7,294,634

Forfeited (in shares)

5,212,127

Exercised (in shares)

584,016

Inducement Award Program | RSUs

Stock-based compensation

Granted (in shares)

535,950

Forfeited (in shares)

232,200

Vested (in shares)

97,812

Equity Incentive Plan 2021 [Member]

Stock-based compensation

Number of shares reserved

23,900,000

Shares available for future grants

18,286,651

Equity Incentive Plan 2021 [Member] | Outstanding stock options

Stock-based compensation

Granted (in shares)

3,717,822

Forfeited (in shares)

14,584

Exercised (in shares)

0

Equity Incentive Plan 2021 [Member] | RSUs

Stock-based compensation

Granted (in shares)

1,971,097

Forfeited (in shares)

0

Vested (in shares)

0

2012 Plan

Stock-based compensation

Number of shares reserved

3,428,571

10,649,876

13,000,000

16,628,425

Additional number of shares authorized for issuance

1,285,714

1,285,714

1,285,714

30,101

Percentage of outstanding shares of common stock used to compute annual increase in number of shares reserved

4.00%

2012 Plan | Maximum

Stock-based compensation

Annual increase in number of shares reserved

1,285,714

2012 Plan | Outstanding stock options

Stock-based compensation

Granted (in shares)

22,098,207

Forfeited (in shares)

8,837,324

Exercised (in shares)

2,198,469

2012 Plan | RSUs

Stock-based compensation

Granted (in shares)

6,678,621

Forfeited (in shares)

1,021,941

Vested (in shares)

5,028,711

Incentive Plan 2021 New Shares [Member]

Stock-based compensation

Number of shares reserved

13,250,124

Stock-based compensation - St_2

Stock-based compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Additional disclosures
Stock-based compensation expense	$ 7,711	$ 8,118	$ 8,539
Outstanding stock options
Stock-based compensation
Expiration term	10 years
Shares
Outstanding at the beginning of the period (in shares)	12,690,745
Granted (in shares)	4,990,731
Exercised (in shares)	(572,086)
Forfeited/cancelled (in shares)	(845,292)
Outstanding at the end of the period (in shares)	16,264,098	12,690,745
Vested at the end of the period (in shares)	9,218,745
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 3.90
Granted (in dollars per share)	2.50
Exercised (in dollars per share)	1.58
Forfeited/cancelled (in dollars per share)	3.71
Outstanding at the end of the period (in dollars per share)	3.56	$ 3.90
Vested at the end of the period (in dollars per share)	$ 4.38
Weighted-average remaining contractual term
Outstanding at the end of the period	6 years 8 months 12 days	6 years 6 months
Vested at the end of the period	4 years 10 months 24 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 3,390
Outstanding at the end of the period (in dollars)	2,601	$ 3,390
Vested at the end of the period (in dollars)	$ 2,150
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)	1.15%	0.60%	1.98%
Volatility (as a percent)	89.00%	96.00%	87.00%
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Expected term	6 years	6 years	5 years 10 months 24 days
Additional disclosures
Stock-based compensation expense	$ 4,100	$ 4,300	$ 7,100
Weighted-average grant date fair value (in dollars per share)	$ 1.82	$ 1.62	$ 1.44
Fair value of vested stock options	$ 3,800	$ 7,400	$ 7,300
Aggregate intrinsic value of options exercised (in dollars)	800	$ 1,000
Total unrecognized stock-based compensation expense (in dollars)	$ 10,700
Weighted-average recognition period	3 years 2 months 12 days
Outstanding stock options | One Year From Vesting
Stock-based compensation
Vesting percentage	25.00%
Vesting period	1 year
Outstanding stock options | Successive Three-Month Periods After One Year From Vesting
Stock-based compensation
Vesting percentage	6.25%
Vesting period	3 months

Stock-based compensation - Rest

Stock-based compensation - Restricted Stock (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)itemtranche$ / sharesshares	Dec. 31, 2020USD ($)employee$ / sharesshares	Dec. 31, 2019USD ($)
Additional disclosures
Stock-based compensation expense	$ 7,711	$ 8,118	$ 8,539
RSUs
Stock-based compensation
Number of shares holder to receive when RSU vests | shares	1
Shares
Unvested at the beginning of the period (in shares) | shares	2,649,317
Granted (in shares) | shares	2,629,312
Vested (in shares) | shares	(2,204,485)
Forfeited (in shares) | shares	(269,140)
Unvested at the end of the period (in shares) | shares	2,805,004	2,649,317
Weighted-average grant date fair value
Unvested at the beginning of the period (in dollars per share) | $ / shares	$ 1.73
Granted (in dollars per share) | $ / shares	2.46
Vested (in dollars per share) | $ / shares	1.66
Forfeited/cancelled (in dollars per share) | $ / shares	2.11
Unvested at the end of the period (in dollars per share) | $ / shares	$ 2.44	$ 1.73
Additional disclosures
Stock-based compensation expense	$ 3,500	$ 3,700	1,000
Fair value of shares vested	3,700	$ 3,800	$ 300
Unrecognized stock-based compensation expense	$ 6,000
Weighted-average recognition period	3 years 8 months 12 days
Number of affected employees | employee		93
Incremental stock compensation expense to be recognized over the remaining requisite service period		$ 200
Incremental stock compensation expense	$ 100	100
RSUs | Selling, general and administrative expenses
Additional disclosures
Stock-based compensation expense		$ 500
RSUs | One Year From Vesting
Stock-based compensation
Number of anniversaries | item	1
Vesting percentage	25.00%
Vesting period	1 year
RSUs | Successive Three-Month Periods After One Year From Vesting
Stock-based compensation
Vesting percentage	6.25%
Vesting period	3 months
RSUs | One Year Anniversary
Stock-based compensation
Number of installments | tranche	2
Vesting percentage	50.00%
Vesting period	1 year
RSUs | Within Two Years of Vesting Commencement
Stock-based compensation
Vesting percentage	100.00%
Vesting period	2 years

Stock-based compensation - Empl

Stock-based compensation - Employee Stock Purchase Plan (Details) $ in Thousands	Dec. 18, 2018itemshares	Dec. 31, 2021USD ($)shares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)shares
Stock-based compensation
Shares reserved for issuance | shares		41,457,000	39,129,000
Assumptions used to estimate fair value of each stock-based award on the grant date
Stock-based compensation expense		$ 7,711	$ 8,118	$ 8,539
Proceeds from the issuance of common stock, net		$ 6,723	$ 106,059
Employee Stock purchase plan
Stock-based compensation
Percent of common stock at market price to be purchased	85.00%
Number of vesting periods | item	2
Vesting period	6 months
Shares reserved for issuance | shares	2,000,000	1,190,000	1,300,000
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)		0.07%	1.04%	2.26%
Volatility (as a percent)		68.00%	109.00%	88.00%
Expected term		6 months	6 months	6 months
Stock-based compensation expense		$ 100	$ 100	$ 400
Issuance of common stock under ESPP | shares		110,060	358,193	341,701
Proceeds from the issuance of common stock, net		$ 200	$ 400	$ 400

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) $ / shares in Units, $ in Thousands	Jul. 16, 2021USD ($)shares	Nov. 06, 2020USD ($)D$ / shares	Dec. 23, 2019USD ($)$ / shares	Nov. 14, 2019USD ($)$ / shares	Oct. 17, 2018USD ($)itemD$ / shares	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)shares	Mar. 31, 2020USD ($)shares	Dec. 31, 2021USD ($)$ / shares	Dec. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)	Jul. 01, 2021USD ($)	Oct. 11, 2018$ / shares
Convertible Notes
Common stock, par value (in dollars per share) | $ / shares									$ 0.0001	$ 0.0001
Change in fair value of conversion option of Notes on exchange										$ 2,331	$ 13,640
Other Nonoperating Income (Expenses)										(1,313)	(641)
Change in fair value of conversion feature										(1,313)	(641)
Interest make-whole payments on the 2019 Notes										$ 1,763	438
5.00% Convertible Senior Notes due 2048
Convertible Notes
Aggregate principal amount		$ 28,000			$ 150,000							$ 28,000
Debt Conversion, Original Debt, Amount			$ 7,400	$ 114,300
Debt Conversion, Converted Instrument, Amount	$ 28,000
Repayments of Convertible Debt			700	11,400
Interest rate (as a percent)					5.00%				5.00%	5.00%
Net proceeds					$ 145,300
Common stock, par value (in dollars per share) | $ / shares					$ 0.0001
Initial conversion rate					139.5771
Initial conversion price of Common Stock | $ / shares					$ 7.16
Conversion premium above the last reported sales price of the Common Stock (as a percent)					15.00%
Sale price of the Common Stock | $ / shares													$ 6.23
Percentage of stock price trigger for conversion					130.00%
Trading days | item					20
Consecutive trading days | D					30
Percentage price of principal amount to be purchased plus accrued and unpaid interest					100.00%
Debt Conversion, Converted Instrument, Shares Issued | shares	8,615,384
5.00% Convertible Senior Second Lien Notes due 2048
Convertible Notes
Debt Conversion, Original Debt, Amount							$ 9,500
Debt Conversion, Converted Instrument, Amount			$ 4,000	$ 62,900				$ 57,400
Interest rate (as a percent)			5.00%	5.00%
Gains (Losses) on Restructuring of Debt									$ 0
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001	$ 0.0001
Initial conversion rate			606.0606	606.0606
Initial conversion price of Common Stock | $ / shares			$ 1.65	$ 1.65
Debt discount			$ 200
Derivative liability			$ 200
Change in fair value of conversion option of Notes on exchange									13,600
Fair value of 2019 Interest Make-Whole Provision						$ 500	500				$ 500
Other Nonoperating Income (Expenses)							$ 600			$ 1,300
Interest expense									10,000
Debt conversion, Converted Instrument, Cash								$ 1,800
Debt Conversion, Converted Instrument, Shares Issued | shares							5,767,872	34,796,350
Interest make-whole payments on the 2019 Notes				$ 400		$ 400
5.00% Convertible Senior Third Lien Notes due 2048
Convertible Notes
Aggregate principal amount		$ 28,000
Interest rate (as a percent)		5.00%
Initial conversion rate		307.6923
Initial conversion price of Common Stock | $ / shares		$ 3.25
Percentage of stock price trigger for conversion		123.08%
Trading days | D		20
Consecutive trading days | D		30
Change in fair value of conversion option of Notes on exchange		$ 2,300
Interest expense									$ 7,800

Net Loss per Share - Potentiall

Net Loss per Share - Potentially Anti-Dilutive Securities Excluded From Calculation of Diluted Net (Loss) Income per Share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	19,168,611	24,050,691	56,910,149
Outstanding stock options
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	16,264,098	12,690,745	17,258,524
RSUs
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	2,805,004	2,649,317	678,089
Employee Stock purchase plan
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	57,636	53,372	227,141
5.00% Convertible Senior Notes due 2048 | Convertible Common Stock [Member]
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	41,873	41,873	3,950,032
5.00% Convertible Senior Second Lien Notes due 2048 | Convertible Common Stock [Member]
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)			34,796,363
5.00% Convertible Senior Third Lien Notes due 2048 | Convertible Common Stock [Member]
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)		8,615,384

Income Taxes - Operating Loss C

Income Taxes - Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2021USD ($)
Federal
Operating loss carryforwards
NOL carryforwards	$ 410.6
Operating loss carryforwards, indefinite period	214.9
State
Operating loss carryforwards
NOL carryforwards	$ 219

Income Taxes - Tax Credits (Det

Income Taxes - Tax Credits (Details) $ in Millions	Dec. 31, 2021USD ($)
Federal
Tax credit carryforwards
Tax credits	$ 3.5
State
Tax credit carryforwards
Tax credits	$ 1.3

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current tax expense:
Federal	$ 0	$ 0	$ 0
State	0	194	0
Current income tax expense	0	194	0
Deferred
Federal	0	0	0
State	0	0	0
Deferred income tax expense	0	0	0
Total income tax expense	$ 0	$ 194	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Taxes and Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of income taxes computed using the U.S. federal statutory rate
Income tax benefit using U.S. federal statutory rate (as a percent)	21.00%	21.00%
State tax benefit, net of federal benefit (as a percent)	3.01%	(8.55%)
Research and development tax credits (as a percent)	2.71%	2.84%
Permanent items (as a percent)	(0.44%)	(0.60%)
Change in the valuation allowance (as a percent)	(21.23%)	35.09%
NOL and tax credit expiration under Section 382 (as a percent)	(4.34%)	(52.67%)
Other (as a percent)	(0.71%)	2.60%
Effective income tax rate (as a percent)		(0.29%)
Deferred tax assets:
Net operating loss carryforwards	$ 98,777	$ 86,665
Capitalized research and development	1,276	1,565
Research and development credits	4,516	2,043
Stock-based compensation	4,200	4,041
Installment sale	8,819	9,981
Lease liability	730	950
Other deferred tax assets	411	680
Total deferred tax assets	118,729	105,925
Deferred tax liabilities:
Right-of-use asset	(574)	(742)
Debt Discount	(11)	(2,245)
Other deferred tax liability	(91)	0
Total deferred tax liabilities	(676)	(2,987)
Net deferred tax asset prior to valuation allowance	118,053	102,938
Valuation allowance	(118,053)	(102,938)
Net deferred tax asset	0	$ 0
Additional disclosures
Increase (decrease) in valuation allowance	15,100
Unrecognized tax benefits	0
Interest and penalties accrued related to unrecognized tax benefits	0
Liability for uncertain tax positions	$ 0

Commitments and contingencies (

Commitments and contingencies (Details) - Office and Laboratory Space in Needham, Massachusetts $ in Millions	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Feb. 15, 2018ft²	Apr. 15, 2014ft²
Property, Plant and Equipment [Line Items]
Area of space | ft²			27,810	15,197
Letter of credit | Restricted Cash and Cash Equivalents, Noncurrent [Member]
Property, Plant and Equipment [Line Items]
Security deposit | $	$ 0.2	$ 0.2

License, collaboration and co_3

License, collaboration and commercial agreements - Secura Bio Inc (Details) $ in Thousands	Jul. 25, 2019USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2021USD ($)item	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Term of agreement		1 year
Revenue recognized			$ 2,053	$ 88,516	$ 17,456
Cost of sales - Sale of COPIKTRA license and related assets				31,187
Copiktra license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales over which royalty payments are due			100
Revenue recognized			1,447	70,000
Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 606	372
Sanofi
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of regulatory milestone achieved | item			2
License and Collaboration Agreement | Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment		$ 70,000
Regulatory milestone payments			$ 1,300
Milestone payments receivable upon approval of COPIKTRA		35,000
Milestone payments receivable upon approval for commercial sale		10,000
Threshold sales to trigger royalty payments		$ 100,000
Percentage of all royalty, milestone and sublicense revenue payments payable		50.00%
Percentage of all royalty and milestone payments payable under certain jurisdictions		50.00%
Future potential royalties expected to be received			$ 200
Cost of sales - Sale of COPIKTRA license and related assets				31,200
Percentage of share on regulatory milestone achieved			50.00%
License and Collaboration Agreement | Secura | Copiktra license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory milestone payments			$ 1,300
Revenue recognized			$ 1,400	70,000
Number of regulatory milestone achieved | item			2
License and Collaboration Agreement | Secura | Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 600	400
License and Collaboration Agreement | Secura | Sales Exceeds $100 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable		$ 10,000
Threshold sales to trigger milestone payments		100,000
License and Collaboration Agreement | Secura | Sales Exceeds $200 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable		15,000
Threshold sales to trigger milestone payments		200,000
License and Collaboration Agreement | Secura | Sales Exceeds $300 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable		25,000
Threshold sales to trigger milestone payments		300,000
License and Collaboration Agreement | Secura | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory milestone payments		45,000
Sales milestone receivable		$ 50,000
License and Collaboration Agreement | Secura | Intangible asset
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of sales - Sale of COPIKTRA license and related assets				19,200
License and Collaboration Agreement | Secura | Duvelisib inventory
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of sales - Sale of COPIKTRA license and related assets				6,000
License and Collaboration Agreement | Secura | Manufacturing equipment
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of sales - Sale of COPIKTRA license and related assets				200
License and Collaboration Agreement | Secura | Duvelisib contract prepaid balances
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of sales - Sale of COPIKTRA license and related assets				$ 5,800
License and Collaboration Agreement | Sanofi
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 42,000

License, collaboration and co_4

License, collaboration and commercial agreements - Secura - Contract asset (Details) - License and Collaboration Agreement $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additions	$ 197
Reclassification to receivable	(27)
Balance at the end of period	170
Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additions	197
Reclassification to receivable	(27)
Balance at the end of period	170
Prepaid Expenses and Other Current Assets | Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Balance at the end of period	$ 200

License, collaboration and co_5

License, collaboration and commercial agreements - Chugai Pharmaceutical Co., Ltd (Chugai) (Details) - Chugai Pharmaceutical Co., Ltd. - License and Collaboration Agreement - USD ($) $ in Millions	Jan. 07, 2020	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
One-time cash payment	$ 3
Agreement obligations expire from first commercial sale of product (in years)	12 years
Number of days written prior notice required for other party to terminate agreement	180 days
Number of days written notice required to terminate agreement if fails to cure breach	120 days
Research and development
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
One-time cash payment		$ 3

License, collaboration and co_6

License, collaboration and commercial agreements - Infinity (Details) - Exclusive license agreement - Infinity - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
License and collaboration agreements
Percentage of additional royalty on worldwide net sales	4.00%
Royalty payments		$ 0	$ 1.3	$ 1

License, collaboration and co_7

License, collaboration and commercial agreements - Sanofi (Details) $ in Thousands	Jul. 25, 2019USD ($)	Aug. 31, 2019USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)Milestone	Dec. 31, 2019USD ($)
License and collaboration agreements
Total revenue			$ 2,053	$ 88,516	$ 17,456
License and collaboration revenue
License and collaboration agreements
Total revenue				$ 2,912	5,117
License and Collaboration Agreement | Sanofi
License and collaboration agreements
Proceeds received		$ 5,000
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 42,000
Number of additional milestones achieved | Milestone				2
License revenue				$ 2,500
Percentage of future milestone payments and royalties entitled			50.00%
License and Collaboration Agreement | Sanofi | License and collaboration revenue
License and collaboration agreements
Total revenue					$ 5,000

License, collaboration and co_8

License, collaboration and commercial agreements - Yakult (Details) - USD ($) $ in Thousands	Jun. 05, 2018	Jun. 30, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
License and collaboration agreements
Total revenue			$ 2,053	$ 88,516	$ 17,456
License and Collaboration Agreement | Yakult
License and collaboration agreements
Proceeds received		$ 10,000
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 90,000
Percentage of future milestone payments and royalties entitled			50.00%

License, collaboration and co_9

License, collaboration and commercial agreements - CSPC (Details) - USD ($) $ in Thousands	Sep. 25, 2018	Aug. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
License and collaboration agreements
Total revenue			$ 2,053	$ 88,516	$ 17,456
License and Collaboration Agreement | CSPC
License and collaboration agreements
Upfront, non-refundable payment obligation to be received prior to initial Exclusivity Fee	$ 15,000
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 160,000
Percentage of future milestone payments and royalties entitled			50.00%
Exclusivity Agreement [Member] | CSPC
License and collaboration agreements
Proceeds received		$ 5,000

Restructurings (Details)

Restructurings (Details) $ in Millions	Feb. 27, 2020position	Oct. 28, 2019position	Aug. 31, 2020position	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Restructuring Costs
Restructuring costs				$ 0	$ 4.6
Selling, general and administrative expenses
Restructuring Costs
Restructuring costs					4.1
Research and development
Restructuring Costs
Restructuring costs					$ 0.5
October 2019 Restructuring | One-time Termination Benefits
Restructuring Costs
Number of eliminated positions | position		40
Restructuring costs						$ 1.2
February 2020 Restructuring | One-time Termination Benefits
Restructuring Costs
Number of eliminated positions | position	31
August 2020 Restructuring | One-time Termination Benefits
Restructuring Costs
Number of eliminated positions | position			41

Restructurings - Restructuring

Restructurings - Restructuring Reserve Activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Restructuring Cost and Reserve [Line Items]
Amounts accrued at, December 31, 2020	$ 1,027
Charges	0
Amount Paid	(1,027)
Adjustments	0
Amounts accrued at, December 31, 2021	0
One-time Termination Benefits | August 2020 Restructuring
Restructuring Cost and Reserve [Line Items]
Amounts accrued at, December 31, 2020	1,027
Charges	0
Amount Paid	(1,027)
Adjustments	0
Amounts accrued at, December 31, 2021	$ 0

Employee benefit plan (Details)

Employee benefit plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee benefit plan
Contributions made under 401(k) plan	$ 0.8	$ 0.9	$ 1.3

Subsequent events (Details)

Subsequent events (Details) - Subsequent events $ in Millions	Mar. 25, 2022USD ($)tranche
Term Loan
Subsequent Event [Line Items]
Face amount	$ 150
Number of tranches | tranche	5
Interest rate (as a percent)	7.37%
Percentage of final prepayment fee	5.00%
Percentage of facility fee	0.50%
Term Loan | If prepaid on or before the first anniversary
Subsequent Event [Line Items]
Percentage of prepayment fee	3.00%
Term Loan | If prepaid after the first anniversary and on or before the second anniversary
Subsequent Event [Line Items]
Percentage of prepayment fee	2.00%
Term Loan | If prepaid after the second anniversary
Subsequent Event [Line Items]
Percentage of prepayment fee	1.00%
Term Loan | Secured Overnight Financing Rate
Subsequent Event [Line Items]
Basis spread	0.13%
Term Loan A
Subsequent Event [Line Items]
Amount drawn	$ 25
Term Loan E
Subsequent Event [Line Items]
Face amount	$ 50