Verastem (VSTM) 10-Q 2 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 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 per share
Trading Symbol	VSTM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		180,758,269
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001526119
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 24,972	$ 67,782
Short-term investments	83,163	73,444
Accounts receivable, net	476	239
Prepaid expenses and other current assets	6,149	3,473
Total current assets	114,760	144,938
Property and equipment, net	270	416
Right-of-use asset, net	2,524	2,726
Restricted cash	241	241
Long-term investments	5,992	5,995
Other assets	103	33
Total assets	123,890	154,349
Current liabilities:
Accounts payable	1,395	1,875
Accrued expenses	10,739	14,660
Lease liability, short-term	610	558
Total current liabilities	12,744	17,093
Non-current liabilities:
Convertible senior notes	20,326	19,051
Lease liability, long-term	2,615	2,931
Total liabilities	35,685	39,075
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized, no shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively
Common stock, $0.0001 par value; 300,000 shares authorized, 172,077 and 170,456 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	17	17
Additional paid-in capital	712,593	707,715
Accumulated other comprehensive income	39	53
Accumulated deficit	(624,444)	(592,511)
Total stockholders' equity	88,205	115,274
Total liabilities and stockholders' equity	$ 123,890	$ 154,349

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Jun. 30, 2021	Dec. 31, 2020
CONDENSED 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	172,077	170,456
Common stock, shares outstanding	172,077	170,456

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue:
Total revenue	$ 500	$ 4,307	$ 1,506	$ 9,363
Operating expenses:
Cost of sales - product		392		887
Cost of sales - intangible amortization		393		785
Research and development	9,730	9,344	18,626	20,268
Selling, general and administrative	6,714	15,442	12,932	35,046
Total operating expenses	16,444	25,571	31,558	56,986
Loss from operations	(15,944)	(21,264)	(30,052)	(47,623)
Other expense				(1,313)
Interest income	49	122	101	478
Interest expense	(1,007)	(1,868)	(1,982)	(12,542)
Net loss	$ (16,902)	$ (23,010)	$ (31,933)	$ (61,000)
Net loss per share-basic and diluted	$ (0.10)	$ (0.14)	$ (0.19)	$ (0.45)
Weighted average common shares outstanding used in computing net loss per share - basic and diluted	171,985	165,395	171,811	136,775
Net loss	$ (16,902)	$ (23,010)	$ (31,933)	$ (61,000)
Unrealized gain (loss) on available-for-sale securities	5	(9)	(14)	(14)
Comprehensive loss	(16,897)	(23,019)	(31,947)	(61,014)
Product revenue, net
Revenue:
Total revenue		4,235		9,269
License and collaboration revenue
Revenue:
Total revenue		$ 72		$ 94
Copiktra license and related assets
Revenue:
Total revenue	52		902
Transition Services Revenue
Revenue:
Total revenue	$ 448		$ 604

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common stock	Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit	Total
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				(37,990)	(37,990)
Unrealized gain (loss) on available-for-sale securities			(5)		(5)
Conversion of 2019 Notes into common stock	$ 3	57,411			57,414
Conversion of 2019 Notes into common stock (in shares)	34,796,350
Issuance of common stock under Employee Stock Purchase Plan		259			259
Issuance of common stock under Employee Stock Purchase Plan (in shares)	227,141
Issuance of common stock resulting from vesting of restricted stock units		(51)			(51)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	58,166
Issuance of common stock resulting from exercise of stock options		983			983
Issuance of common stock resulting from exercise of stock options (in shares)	645,628
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		1,370			1,370
Balance at Mar. 31, 2020	$ 16	685,733	9	(562,775)	122,983
Balance (in shares) at Mar. 31, 2020	162,356,444
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					(61,000)
Unrealized gain (loss) on available-for-sale securities					(14)
Balance at Jun. 30, 2020	$ 17	700,141		(585,785)	114,373
Balance (in shares) at Jun. 30, 2020	169,337,919
Balance at Mar. 31, 2020	$ 16	685,733	9	(562,775)	122,983
Balance (in shares) at Mar. 31, 2020	162,356,444
Increase (Decrease) in Stockholders' Equity
Net loss				(23,010)	(23,010)
Unrealized gain (loss) on available-for-sale securities			(9)		(9)
Issuance of common stock resulting from vesting of restricted stock units		(31)			(31)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	32,650
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 exercise of stock options		551			551
Issuance of common stock resulting from exercise of stock options (in shares)	179,266
Stock-based compensation expense		1,659			1,659
Balance at Jun. 30, 2020	$ 17	700,141		(585,785)	114,373
Balance (in shares) at Jun. 30, 2020	169,337,919
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				(15,031)	$ (15,031)
Unrealized gain (loss) on available-for-sale securities			(19)		(19)
Issuance of common stock under Employee Stock Purchase Plan		76			76
Issuance of common stock under Employee Stock Purchase Plan (in shares)	53,372
Issuance of common stock resulting from vesting of restricted stock units		(52)			(52)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	1,047,271
Issuance of common stock resulting from exercise of stock options		381			381
Issuance of common stock resulting from exercise of stock options (in shares)	173,890
Stock-based compensation expense		1,980			1,980
Balance at Mar. 31, 2021	$ 17	710,100	34	(607,542)	102,609
Balance (in shares) at Mar. 31, 2021	171,730,712
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					$ (31,933)
Unrealized gain (loss) on available-for-sale securities					(14)
Balance at Jun. 30, 2021	$ 17	712,593	39	(624,444)	$ 88,205
Balance (in shares) at Jun. 30, 2021	172,077,366				172,077,000
Balance at Mar. 31, 2021	$ 17	710,100	34	(607,542)	$ 102,609
Balance (in shares) at Mar. 31, 2021	171,730,712
Increase (Decrease) in Stockholders' Equity
Net loss				(16,902)	(16,902)
Unrealized gain (loss) on available-for-sale securities			5		5
Issuance of common stock resulting from vesting of restricted stock units		(38)			(38)
Issuance of common stock resulting from vesting of restricted stock units (in shares)	15,896
Issuance of common stock resulting from exercise of stock options		361			361
Issuance of common stock resulting from exercise of stock options (in shares)	330,758
Stock-based compensation expense		2,170			2,170
Balance at Jun. 30, 2021	$ 17	$ 712,593	$ 39	$ (624,444)	$ 88,205
Balance (in shares) at Jun. 30, 2021	172,077,366				172,077,000

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020
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

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (31,933)	$ (61,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	146	189
Amortization of acquired intangible asset		785
Amortization of right-of-use asset and lease liability	(62)	(8)
Stock-based compensation expense	4,150	3,029
Amortization of deferred financing costs, debt discounts and premiums and discounts on available-for-sale marketable securities	1,328	9,259
Change in fair value of interest make whole provision for 2019 Notes		1,313
Changes in operating assets and liabilities:
Accounts receivable, net	(237)	1,024
Inventory		(3,220)
Prepaid expenses, other current assets and other assets	(2,746)	(2,819)
Accounts payable	(284)	(7,414)
Accrued expenses and other liabilities	(3,104)	2,312
Net cash used in operating activities	(32,742)	(56,550)
Investing activities
Purchases of property and equipment	(196)	(27)
Purchases of investments	(53,258)
Maturities of investments	43,475	32,050
Net cash (used in) provided by investing activities	(9,979)	32,023
Financing activities
Proceeds from the exercise of stock options and employee stock purchase program	818	1,793
Interest make-whole payments on the 2019 Notes		(1,763)
Settlement of restricted stock for tax withholdings	(907)
Proceeds from the issuance of common stock, net		106,069
Net cash (used in) provided by financing activities	(89)	106,099
(Decrease) increase in cash, cash equivalents and restricted cash	(42,810)	81,572
Cash, cash equivalents and restricted cash at beginning of period	68,023	79,262
Cash, cash equivalents and restricted cash at end of period	25,213	160,834
Supplemental disclosure of non-cash investing and financing activities
Common stock issuance costs included in accounts payable and accrued expenses	15	25
Conversion of 2019 Notes into common stock		57,414
Purchases of property and equipment included in accounts payable and accrued expenses		6
Settlement of restricted stock units for tax withholdings included in accrued expenses	$ 18	$ 82

Nature of business

Nature of business	6 Months Ended
	Jun. 30, 2021
Nature of business
Nature of business	1. Nature of business Verastem, Inc. (the Company) is a biopharmaceutical company 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. The Company’s most advanced product candidates, VS-6766 and defactinib, are being investigated in both preclinical and clinical studies for treatment of various solid tumors, including low-grade serous ovarian cancer, non-small cell lung cancer, colorectal cancer, pancreatic cancer, uveal melanoma, and endometrial cancer. The Company believes that VS-6766 may be beneficial as therapeutics as a single agent or these compounds may be beneficial as therapeutics when used together in combination with other agents , 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 13. License, collaboration, and commercial agreements The condensed 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 June 30, 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.

Summary of significant accounti

Summary of significant accounting policies	6 Months Ended
	Jun. 30, 2021
Summary of significant accounting policies
Summary of significant accounting policies	2. Summary of significant accounting policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States (GAAP) for interim financial reporting and as required by Regulation S-X, Rule 10-01 under the assumption that the Company will continue as a going concern for the next twelve months. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, or any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2021 are not necessarily indicative of the results that may be expected for any other interim period or for the year ending December 31, 2021. For further information, refer to the financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the Securities and Exchange Commission (SEC) on March 18, 2021. Significant Accounting Policies No te 2 . Significant accounting policies in the Recently Adopted Accounting Standards Updates” . Recently Adopted Accounting Standards Updates Recently Issued Accounting Standards Updates In June 2016, the FASB issued 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 condensed 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 condensed consolidated financial statements and related disclosures. Concentrations of credit risk and off-balance sheet risk Cash, 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 June 30, 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 June 30, 2021 there was one customer, Secura, that made up more than 60% of the Company’s accounts receivable balance. The Company assesses the creditworthiness of all its customers and sets and reassesses customer credit limits to ensure collectability of any accounts receivable balances are assured. For the three and six months ended June 30, 2021, there was one customer, Secura, who individually accounted for all of the Company’s revenue. Refer to Note 13. License, collaboration, and commercial agreements

Cash, cash equivalents and rest

Cash, cash equivalents and restricted cash	6 Months Ended
	Jun. 30, 2021
Cash, cash equivalents and restricted cash
Cash, cash equivalents and restricted cash	3. Cash, cash equivalents and restricted cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Cash and cash equivalents ​ $ 24,972 ​ $ 67,782 Restricted cash ​ 241 ​ 241 Total cash, cash equivalents and restricted cash ​ $ 25,213 ​ $ 68,023 ​ Amounts included in restricted cash as of June 30, 2021 and December 31, 2020 represent cash held to collateralize outstanding letters of credit provided as a security deposit for the Company’s office space located in Needham, Massachusetts in the amount of approximately $0.2 million. The letters of credit are included in non-current restricted cash on the condensed consolidated balance sheets at June 30, 2021 and December 31, 2020.

Fair value of financial instrum

Fair value of financial instruments	6 Months Ended
	Jun. 30, 2021
Fair value of financial instruments
Fair value of financial instruments	4. 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): a ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 23,029 ​ $ 19,029 ​ $ 4,000 ​ $ — ​ Short-term investments ​ ​ 83,163 ​ ​ — ​ ​ 83,163 ​ ​ — ​ Long-term investments ​ ​ 5,992 ​ ​ — ​ ​ 5,992 ​ ​ — ​ Total financial assets ​ $ 112,184 ​ $ 19,029 ​ $ 93,155 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ $ — ​ ​ The Company’s cash equivalents and short-term investments consist of U.S. Government money market funds, corporate bonds, agency bonds and commercial paper of publicly traded companies. The investments and cash equivalents have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market-based approaches and observable market inputs to determine value. These observable market inputs include reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates and other industry and economic events. The Company validates the prices provided by third party pricing services by reviewing their pricing methods and matrices, obtaining market values from other pricing sources, analyzing pricing data in certain instances and 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 June 30, 2021 and December 31, 2020. Fair Value of Financial Instruments The fair value of the Company’s 2018 issued 5.00% Convertible Senior Notes due 2048 (the 2018 Notes) and 2020 issued 5.00% Convertible Senior Notes due 2048 (the 2020 Notes, together with the 2018 Notes referred to as the Notes) was approximately $0.3 million and $36.8 million, respectively, as of June 30, 2021, which differs from the aggregate carrying value of the Notes of $20.3 million as of June 30, 2021. The fair value of the 2018 Notes and 2020 Notes was approximately $0.3 million and $30.0 million, respectively, as of December 31, 2020, which differs from the aggregate carrying value of the Notes of $19.1 million as of December 31, 2020. The fair value of the Notes is influenced by the Company’s stock price, stock price volatility, and current market yields and was determined using Level 3 inputs.

Investments

Investments	6 Months Ended
	Jun. 30, 2021
Investments
Investments	5. Investments Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 21,213 ​ $ — ​ $ — ​ $ 21,213 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 3,999 ​ ​ 1 ​ ​ — ​ ​ 4,000 ​ Total cash, cash equivalents & restricted cash: ​ $ 25,212 ​ $ 1 ​ $ — ​ $ 25,213 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 83,118 ​ $ 47 ​ $ (2) ​ $ 83,163 ​ Corporate bonds, agency bonds and commercial paper (due between 1 and 5 years ) ​ ​ 5,999 ​ ​ — ​ ​ (7) ​ ​ 5,992 ​ Total investments ​ $ 89,117 ​ $ 47 ​ $ (9) ​ $ 89,155 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 114,329 ​ $ 48 ​ $ (9) ​ $ 114,368 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ ​ There were no realized gains or losses on investments for the three and six months ended June 30, 2021 or 2020. There were

Accrued expenses

Accrued expenses	6 Months Ended
	Jun. 30, 2021
Accrued expenses
Accrued expenses	6. Accrued expenses Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Research and development expenses ​ $ 5,880 ​ $ 5,176 ​ Compensation and related benefits ​ 2,274 ​ 5,930 ​ Professional fees ​ 707 ​ 615 ​ Consulting fees ​ 551 ​ 1,091 ​ Interest ​ ​ 236 ​ ​ 236 ​ Commercialization costs ​ 28 ​ 330 ​ Other ​ 1,063 ​ 1,282 ​ Total accrued expenses ​ $ 10,739 ​ $ 14,660 ​ ​

Product revenue reserves and al

Product revenue reserves and allowances	6 Months Ended
	Jun. 30, 2021
Product revenue reserves and allowances
Product revenue reserves and allowances	7. 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 ​ Government ​ ​ ​ ​ ​ ​ ​ ​ discounts ​ rebates and ​ ​ ​ ​ ​ ​ ​ ​ and ​ other ​ ​ ​ ​ ​ ​ ​ allowances incentives Returns Total 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 June 30, 2021 ​ $ — ​ $ — ​ $ — ​ $ — ​

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases
Leases	8. 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. 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 $0.7 million, 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 condensed 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. As of June 30, 2021, a right-of-use asset of $2.5 million and lease liability of $3.2 million are reflected on the condensed consolidated balance sheets. The elements of lease expense were as follows (dollar amounts in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Lease Expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ ​ $ 221 ​ $ 221 ​ $ 442 ​ $ 442 Total Lease Expense ​ ​ $ 221 ​ $ 221 ​ $ 442 ​ $ 442 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ ​ $ 252 ​ $ 247 ​ $ 504 ​ $ 451 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4.0 Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 514 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,039 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,060 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 4,240 Less: Present value discount ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,015) Lease Liability ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 3,225 ​ ​

Convertible Senior Notes

Convertible Senior Notes	6 Months Ended
	Jun. 30, 2021
Convertible Senior Notes
Convertible Senior Notes	9. Convertible Senior Notes 2018 Notes Convertible Senior Notes due 2048 (the 2018 Notes). The 2018 Notes are governed by the terms of a base indenture for senior debt securities (the 2018 Base Indenture), as supplemented by the first supplemental indenture thereto (the 2018 Notes 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, as trustee. The 2018 Notes are senior unsecured obligations of the Company and bear interest at a rate of 2019 Notes The Company had the right, exercisable at the Company’s option, to cause all 2019 Notes then outstanding to be converted automatically if the “Daily VWAP” (as defined in the 2019 Indenture) per share of the Company’s common stock equaled or exceeded 121% of the conversion price on each of at least 20 VWAP Trading Days, whether or not consecutive, during any 30 consecutive VWAP Trading Day period commencing on or after the date the Company first issued the 2019 Notes. (Company’s 2019 Notes Mandatory Conversion Option). Upon conversion, converting noteholders were entitled to receive accrued interest on their converted 2019 Notes. In addition, if the 2019 Notes were converted with a conversion date that is on or prior to November 1, 2020, other than in connection with the Company’s exercise of the Company’s 2019 Notes Mandatory Conversion Option then the consideration due upon any such conversion will also include a cash interest make-whole payment for all future scheduled interest payments on the converted 2019 Notes through November 1, 2020 (2019 Notes Interest Make-Whole Provision). 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 and $1.8 million of cash for the 2019 Note Interest Make-Whole Provision. The Company recorded $1.3 million for the six months ended June 30, 2020 as other expense for the change in fair value of the 2019 Notes Interest Make-Whole Provision in the condensed consolidated statements of operations and comprehensive loss. 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 is 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 are governed pursuant to the Base Indenture between the Company and Wilmington Trust, National Association, 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 will have 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 equals or exceeds 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 is 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, representing an approximately 153.9% premium to the sale price of $1.28 per share of the Company’s common stock on November 5, 2020, as reported on the Nasdaq Global Market. 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, 2023, the Company will not have the right to redeem the 2020 Notes. On or after November 1, 2023, the Company may elect 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 has previously called all outstanding 2020 Notes for redemption, the 2020 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 2020 Notes to be repurchased, plus accrued and unpaid interest, if any. If a Fundamental Change (as defined in the 2020 Indenture) occurs at any time, subject to certain conditions, holders may require the Company to purchase all or any portion of their 2020 Notes at a purchase price equal to 100% of the principal amount of the 2020 Notes to be purchased, plus accrued and unpaid interest, if any, to, but excluding, the “Fundamental Change Repurchase Date” (as defined in the 2020 Indenture). If a “Make-Whole Fundamental Change” (as defined in the 2020 Indenture) occurs on or before November 1, 2022 and a holder elects to convert its 2020 Notes in connection with such Make-Whole Fundamental Change, such holder may be entitled to an increase in the conversion rate in certain circumstances as set forth in the 2020 Indenture. Upon conversion of the 2020 Notes, holders will receive a cash payment equal to the accrued and unpaid interest on the converted 2020 Notes. The 2020 Notes are the Company’s senior unsecured obligations and will be senior in right of payment to the Company’s future indebtedness that is expressly subordinated in right of payment to the 2020 Notes, and equal in right of payment with the Company’s existing and future indebtedness that is not so subordinated, and effectively subordinated to the Company’s existing and future indebtedness, to the extent of the value of the collateral securing such indebtedness. The 2020 Notes are structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and (to the extent the Company is not a holder thereof) preferred equity, if any, of the Company’s subsidiaries. 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 condensed 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 June 30, 2021. Refer to Note 17. Subsequent events

Common stock

Common stock	6 Months Ended
	Jun. 30, 2021
Common stock.
Common stock	10. Common stock Private Investment in Public Equity (PIPE) On February 27, 2020, the Company entered into a Securities Purchase Agreement (Purchase Agreement) with certain institutional investors in which the Company agreed to sell 46,511,628 shares of common stock at a purchase price of $2.15 per share, which represents 12.6% premium to the last reported sale price of the Company’s common stock of $1.91 per share on February 27, 2020. On March 3, 2020, the closing occurred. The aggregate proceeds net of underwriting discounts and offering costs, were approximately $93.8 million. At-the-market equity offering programs In March 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 Fitzgerald & Co. (Cantor) as sales agent. In August 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. During the six months ended June 30, 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). The Company did not make any sales under this program during the three and six months ended June 30, 2021. Through June 30, 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).

Stock-based compensation

Stock-based compensation	6 Months Ended
	Jun. 30, 2021
Stock-based compensation
Stock-based compensation	11. Stock-based compensation Stock options A summary of the Company’s stock option activity and related information for the six months ended June 30, 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 1,098,371 ​ ​ 2.75 ​ ​ ​ ​ ​ ​ Exercised (487,516) ​ ​ 1.52 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (808,975) ​ ​ 3.75 ​ ​ ​ ​ ​ ​ Outstanding at June 30, 2021 12,492,625 ​ $ 3.90 6.2 ​ $ 18,886 ​ Vested at June 30, 2021 8,181,296 ​ $ 4.58 5.0 ​ $ 11,731 ​ ​ The fair value of each stock option granted during the six months ended June 30, 2021 and 2020 was estimated on the grant date using the Black-Scholes option-pricing model using the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ ​ 2021 ​ 2020 Risk-free interest rate 0.66 % ​ 0.40 % Volatility 95 % ​ 97 % Dividend yield — ​ ​ — ​ Expected term (years) 5.8 ​ ​ 5.6 ​ ​ Restricted stock units (RSUs) A summary of the Company’s RSU activity and related information for the six months ended June 30, 2021 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average grant date fair value per share Outstanding at December 31, 2020 ​ 2,649,317 ​ $ 1.73 ​ Granted ​ 635,090 ​ $ 2.72 ​ Vested ​ (107,390) ​ $ 2.16 ​ Forfeited/cancelled ​ ​ (243,562) ​ $ 2.10 ​ Outstanding at June 30, 2021 ​ 2,933,455 ​ $ 1.90 ​ ​ Employee stock purchase plan 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 following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ ​ 2021 ​ 2020 Risk-free interest rate 0.09 % ​ 1.57 % Volatility 65 % ​ 78 % Dividend yield — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​ ​

Net loss per share

Net loss per share	6 Months Ended
	Jun. 30, 2021
Net loss per share
Net loss per Share	12. Net loss per share Basic 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 employee stock purchase plan shares (using the “treasury stock” method), and the Notes (using the “if-converted” method), unless their effect on net loss per share is anti-dilutive. The following potentially dilutive securities were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ 2021 2020 2021 2020 Outstanding stock options 12,492,625 13,400,155 ​ 12,492,625 13,400,155 ​ Outstanding restricted stock units ​ 2,933,455 ​ 1,476,148 ​ 2,933,455 ​ 1,476,148 ​ 2018 Notes ​ 41,873 ​ 3,950,032 ​ 41,873 ​ 3,950,032 ​ 2020 Notes ​ 8,615,384 ​ — ​ 8,615,384 ​ — ​ Employee stock purchase plan ​ 56,688 ​ 131,052 ​ 56,688 ​ 131,052 ​ Total potentially dilutive securities 24,140,025 18,957,387 ​ 24,140,025 18,957,387 ​ ​

License, collaboration and comm

License, collaboration and commercial agreements	6 Months Ended
	Jun. 30, 2021
License, collaboration and commercial agreements
License, collaboration and commercial agreements	13. 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. Pursuant to the terms of the Secura APA, Secura has paid the Company an up-front payment of $70.0 million and agreed to the 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 will provide certain support functions at Secura’s direction for a term of less than one year from the date of execution, unless earlier terminated or extended according to the terms of the Secura TSA (Secura TSA Services). Secura may cancel the Secura TSA at sole discretion for any or no reason with five days ' notice. Services performed are 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 $0.1 million of future potential royalties the Company expects to receive pursuant to the Secura APA were not constrained as of June 30, 2021. When estimating the amount of royalties to be received that was 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 June 30, 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. As the consideration for future royalties is conditional, the Company recorded a corresponding contract asset for the expected royalties. Portions of the contract asset will be reclassified to accounts receivable when the right to consideration becomes unconditional. As of June 30, 2021, the $0.1 million contract asset has been recorded within prepaid and other current assets on the condensed consolidated balance sheet. The following table presents changes in the Company’s contract asset for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: Balance at Additions ​ Reclassification to receivable ​ Balance at Contract asset - Secura ​ ​ — ​ ​ 152 ​ ​ (22) ​ ​ 130 Total $ — ​ $ 152 ​ $ (22) ​ $ 130 ​ During the first quarter of 2021, one regulatory milestone was achieved by Secura’s sublicensee, Sanofi, of which 50% of the milestone or $0.8 million is due 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 June 30, 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 three and six months ended June 30, 2021, the Company recognized $0.1 million and $0.9 million, respectively of sale of COPIKTRA license and related assets revenue within the statements of operations and comprehensive loss. The sale of COPIKTRA license and related asset revenue for the three months ended June 30, 2021, primarily related $0.1 million related to future royalties expected to be received pursuant to the Secura APA. The sale of COPIKTRA license and related assets revenue for the six months ended June 30, 2021 primarily related to 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 ) 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. As discussed above as of September 30, 2020, Secura has assumed from the Company all responsibilities and obligations under the Sanofi Agreement. After September 30, 2020, the Company is entitled to 50% of future milestone payments and royalties pursuant to the Secura APA discussed under heading Secura Bio, Inc. (Secura) Yakult Honsha Co., Ltd. (Yakult) On June 5, 2018, the Company entered into a license and collaboration agreement with Yakult (the Yakult Agreement), 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 on a pro-rata basis. As discussed above as of September 30, 2020, Secura has assumed from the Company all responsibilities and obligations under the Yakult Agreement. After September 30, 2020, the Company is entitled to 50% of future milestone payments and royalties pursuant to the Secura APA discussed under heading 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 (each, a Region and collectively, the CSPC Territory) for the treatment, prevention, palliation or diagnosis of all oncology indications in humans. CSPC paid the Company an aggregate upfront, non-refundable payment of $15.0 million in 2018. 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, subject to reduction in certain circumstances, and to fund certain global development costs related to worldwide clinical trials conducted by the Company in which CSPC has opted to participate on a pro-rata basis. As discussed above as of September 30, 2020, Secura has assumed from the Company all responsibilities and obligations under the CSPC Agreement. After September 30, 2020, the Company is entitled to 50% of future milestone payments and royalties pursuant to the Secura APA discussed under heading Secura Bio, Inc. (Secura)

Income taxes

Income taxes	6 Months Ended
	Jun. 30, 2021
Income taxes
Income taxes	14. Income taxes

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and contingencies
Commitments and contingencies	15. Commitments and contingencies The Company has no other commitments other than minimum lease payments as disclosed in Note 8. Leases.

Restructurings

Restructurings	6 Months Ended
	Jun. 30, 2021
Restructurings
Restructurings	16. Restructurings On February 27, 2020, following 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 was designed to streamline operations, speed execution of the Company’s clinical development of defactinib and VS-6766, and reflect a focused, account-based approach in the field. During the three and six months ended June 30, 2020, the Company recorded an aggregate expense of $0.0 million and $1.8 million, respectively, which is reflected in the condensed consolidated statements of operations and comprehensive loss as selling general, and administrative expense for $0.0 million and $1.4 million, respectively, and research and development expense of $0.0 million and $0.4 million, respectively, for one-time termination benefits for employee severance, benefits, and related costs for the February 2020 Restructuring. 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. The following table summarizes the accrued liabilities activity recorded in connection with the restructurings for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee severance, benefits and related costs Amounts Charges ​ Amount ​ Adjustments ​ Amounts August 2020 Restructuring ​ ​ 1,027 ​ ​ — ​ ​ (1,014) ​ ​ — ​ ​ 13 Total $ 1,027 ​ $ — ​ $ (1,014) ​ $ — ​ $ 13 ​ ​ ​

Subsequent events

Subsequent events	6 Months Ended
	Jun. 30, 2021
Subsequent events
Subsequent events	17. Subsequent events The Company reviews all activity subsequent to the end of the quarter but prior to issuance of the condensed consolidated financial statements for events that could require disclosure or that could impact the carrying value of assets or liabilities as of the balance sheet date. The Company is not aware of any material subsequent events other than the following: 2020 Notes Conversion 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 has been converted into 8,615,384 shares of common stock. As a result, as of the date these condensed consolidated financial statements are issued there is $0.0 million aggregate principal amount outstanding of 2020 Notes. ​

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	6 Months Ended
	Jun. 30, 2021
Summary of significant accounting policies
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States (GAAP) for interim financial reporting and as required by Regulation S-X, Rule 10-01 under the assumption that the Company will continue as a going concern for the next twelve months. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements, or any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2021 are not necessarily indicative of the results that may be expected for any other interim period or for the year ending December 31, 2021. For further information, refer to the financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the Securities and Exchange Commission (SEC) on March 18, 2021.
Significant Accounting Policies	Significant Accounting Policies No te 2 . Significant accounting policies in the Recently Adopted Accounting Standards Updates” .
Recently Adopted and/or Issued Accounting Standards Updates	Recently Adopted Accounting Standards Updates Recently Issued Accounting Standards Updates In June 2016, the FASB issued 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 condensed 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 condensed consolidated financial statements and related disclosures.
Concentrations of credit risk and off-balance sheet risk	Concentrations of credit risk and off-balance sheet risk Cash, 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 June 30, 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 June 30, 2021 there was one customer, Secura, that made up more than 60% of the Company’s accounts receivable balance. The Company assesses the creditworthiness of all its customers and sets and reassesses customer credit limits to ensure collectability of any accounts receivable balances are assured. For the three and six months ended June 30, 2021, there was one customer, Secura, who individually accounted for all of the Company’s revenue. Refer to Note 13. License, collaboration, and commercial agreements

Cash, cash equivalents and re_2

Cash, cash equivalents and restricted cash (Tables)	6 Months Ended
	Jun. 30, 2021
Cash, cash equivalents and restricted cash
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 condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Cash and cash equivalents ​ $ 24,972 ​ $ 67,782 Restricted cash ​ 241 ​ 241 Total cash, cash equivalents and restricted cash ​ $ 25,213 ​ $ 68,023 ​

Fair value of financial instr_2

Fair value of financial instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Fair value of financial instruments
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): a ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 23,029 ​ $ 19,029 ​ $ 4,000 ​ $ — ​ Short-term investments ​ ​ 83,163 ​ ​ — ​ ​ 83,163 ​ ​ — ​ Long-term investments ​ ​ 5,992 ​ ​ — ​ ​ 5,992 ​ ​ — ​ Total financial assets ​ $ 112,184 ​ $ 19,029 ​ $ 93,155 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​ $ — ​

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2021
Investments
Schedule of cash, cash equivalents and investments	Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 21,213 ​ $ — ​ $ — ​ $ 21,213 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 3,999 ​ ​ 1 ​ ​ — ​ ​ 4,000 ​ Total cash, cash equivalents & restricted cash: ​ $ 25,212 ​ $ 1 ​ $ — ​ $ 25,213 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 83,118 ​ $ 47 ​ $ (2) ​ $ 83,163 ​ Corporate bonds, agency bonds and commercial paper (due between 1 and 5 years ) ​ ​ 5,999 ​ ​ — ​ ​ (7) ​ ​ 5,992 ​ Total investments ​ $ 89,117 ​ $ 47 ​ $ (9) ​ $ 89,155 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 114,329 ​ $ 48 ​ $ (9) ​ $ 114,368 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 ​

Accrued expenses (Tables)

Accrued expenses (Tables)	6 Months Ended
	Jun. 30, 2021
Accrued expenses
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Research and development expenses ​ $ 5,880 ​ $ 5,176 ​ Compensation and related benefits ​ 2,274 ​ 5,930 ​ Professional fees ​ 707 ​ 615 ​ Consulting fees ​ 551 ​ 1,091 ​ Interest ​ ​ 236 ​ ​ 236 ​ Commercialization costs ​ 28 ​ 330 ​ Other ​ 1,063 ​ 1,282 ​ Total accrued expenses ​ $ 10,739 ​ $ 14,660 ​

Product revenue reserves and _2

Product revenue reserves and allowances (Tables)	6 Months Ended
	Jun. 30, 2021
Product revenue reserves and allowances
Schedule of product revenue allowance and reserve categories	The following table summarizes activity in each of the product revenue allowance and reserve categories for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade ​ Government ​ ​ ​ ​ ​ ​ ​ ​ discounts ​ rebates and ​ ​ ​ ​ ​ ​ ​ ​ and ​ other ​ ​ ​ ​ ​ ​ ​ allowances incentives Returns Total 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 June 30, 2021 ​ $ — ​ $ — ​ $ — ​ $ —

Lease (Tables)

Lease (Tables)	6 Months Ended
	Jun. 30, 2021
Leases
Summary of elements of lease expenses	The elements of lease expense were as follows (dollar amounts in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 Lease Expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ ​ $ 221 ​ $ 221 ​ $ 442 ​ $ 442 Total Lease Expense ​ ​ $ 221 ​ $ 221 ​ $ 442 ​ $ 442 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ ​ $ 252 ​ $ 247 ​ $ 504 ​ $ 451 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4.0 Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 514 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,039 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,060 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 4,240 Less: Present value discount ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,015) Lease Liability ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 3,225

Stock-based compensation (Table

Stock-based compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Stock-based compensation
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 1,098,371 ​ ​ 2.75 ​ ​ ​ ​ ​ ​ Exercised (487,516) ​ ​ 1.52 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (808,975) ​ ​ 3.75 ​ ​ ​ ​ ​ ​ Outstanding at June 30, 2021 12,492,625 ​ $ 3.90 6.2 ​ $ 18,886 ​ Vested at June 30, 2021 8,181,296 ​ $ 4.58 5.0 ​ $ 11,731 ​ ​
Schedule of assumptions used to estimate fair value of each stock option on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ ​ 2021 ​ 2020 Risk-free interest rate 0.66 % ​ 0.40 % Volatility 95 % ​ 97 % Dividend yield — ​ ​ — ​ Expected term (years) 5.8 ​ ​ 5.6 ​
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 ​ 635,090 ​ $ 2.72 ​ Vested ​ (107,390) ​ $ 2.16 ​ Forfeited/cancelled ​ ​ (243,562) ​ $ 2.10 ​ Outstanding at June 30, 2021 ​ 2,933,455 ​ $ 1.90 ​
Schedule of assumptions used to estimate fair value of each employee stock purchase plan on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended June 30, ​ ​ ​ 2021 ​ 2020 Risk-free interest rate 0.09 % ​ 1.57 % Volatility 65 % ​ 78 % Dividend yield — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​

Net loss per share (Tables)

Net loss per share (Tables)	6 Months Ended
	Jun. 30, 2021
Net loss per share
Schedule of potentially anti-dilutive securities excluded from calculation of diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended June 30, ​ Six months ended June 30, ​ ​ 2021 2020 2021 2020 Outstanding stock options 12,492,625 13,400,155 ​ 12,492,625 13,400,155 ​ Outstanding restricted stock units ​ 2,933,455 ​ 1,476,148 ​ 2,933,455 ​ 1,476,148 ​ 2018 Notes ​ 41,873 ​ 3,950,032 ​ 41,873 ​ 3,950,032 ​ 2020 Notes ​ 8,615,384 ​ — ​ 8,615,384 ​ — ​ Employee stock purchase plan ​ 56,688 ​ 131,052 ​ 56,688 ​ 131,052 ​ Total potentially dilutive securities 24,140,025 18,957,387 ​ 24,140,025 18,957,387 ​

License, collaboration and co_2

License, collaboration and commercial agreements (Tables)	6 Months Ended
	Jun. 30, 2021
License, collaboration and commercial agreements
Schedule of contract assets	The following table presents changes in the Company’s contract asset for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: Balance at Additions ​ Reclassification to receivable ​ Balance at Contract asset - Secura ​ ​ — ​ ​ 152 ​ ​ (22) ​ ​ 130 Total $ — ​ $ 152 ​ $ (22) ​ $ 130

Restructurings (Tables)

Restructurings (Tables)	6 Months Ended
	Jun. 30, 2021
Restructurings
Schedule of accrued restructuring liabilities	The following table summarizes the accrued liabilities activity recorded in connection with the restructurings for the six months ended June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee severance, benefits and related costs Amounts Charges ​ Amount ​ Adjustments ​ Amounts August 2020 Restructuring ​ ​ 1,027 ​ ​ — ​ ​ (1,014) ​ ​ — ​ ​ 13 Total $ 1,027 ​ $ — ​ $ (1,014) ​ $ — ​ $ 13

Nature of business (Details)

Nature of business (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Nature of business
Cash, cash equivalents, restricted cash and investments	$ 114,100
Accumulated deficit	$ (624,444)	$ (592,511)

Significant accounting policies

Significant accounting policies - Concentration of Credit Risk (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2021customer	Jun. 30, 2021customerInstitution
Concentrations of credit risk and off-balance sheet risk
Off-balance sheet concentrations of credit risk description		As of June 30, 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 | Secura
Concentrations of credit risk and off-balance sheet risk
Number of customer		1
Trade accounts receivable | Credit Concentration Risk | Secura | Minimum
Concentrations of credit risk and off-balance sheet risk
Percentage		60.00%
Revenue | Customer Concentration Risk | Secura
Concentrations of credit risk and off-balance sheet risk
Number of customer	1	1

Cash, cash equivalents and re_3

Cash, cash equivalents and restricted cash - Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash, cash equivalents and restricted cash
Cash, cash equivalents & restricted cash, Amortized Cost	$ 24,972	$ 67,782
Restricted cash	241	241
Total cash, cash equivalents and restricted cash	$ 25,213	$ 68,023	$ 160,834	$ 79,262

Cash, cash equivalents and re_4

Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	$ 241	$ 241
Letter of credit | Office and Laboratory Space in Needham, Massachusetts
Property, Plant and Equipment [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	$ 200	$ 200

Fair value of financial instr_3

Fair value of financial instruments - Fair value (Details) - Recurring basis - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financial assets
Cash equivalents	$ 23,029	$ 65,610
Short-term investments	83,163	73,444
Long-term investments	5,992	5,995
Total financial assets	112,184	145,049
Level 1
Financial assets
Cash equivalents	19,029	60,611
Total financial assets	19,029	60,611
Level 2
Financial assets
Cash equivalents	4,000	4,999
Short-term investments	83,163	73,444
Long-term investments	5,992	5,995
Total financial assets	$ 93,155	$ 84,438

Fair value of financial instr_4

Fair value of financial instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Nov. 06, 2020	Oct. 17, 2018
5.00% Convertible Senior Notes due 2048
Financial liabilities
Interest rate (as a percent)	5.00%			5.00%
5.00% Convertible Senior Third Lien Notes due 2048
Financial liabilities
Interest rate (as a percent)			5.00%
Level 3 | 5.00% Convertible Senior Notes due 2048
Financial liabilities
Debt, fair value	$ 0.3	$ 0.3
Debt, carrying value	20.3	19.1
Level 3 | 5.00% Convertible Senior Third Lien Notes due 2048
Financial liabilities
Debt, fair value	$ 36.8	$ 30

Investments (Details)

Investments (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021USD ($)item	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)item	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)item
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Amortized Cost	$ 24,972		$ 24,972		$ 67,782
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Gains	48		48		56
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Losses	(9)		(9)		$ (3)
Total cash, cash equivalents, restricted cash and investments, Fair Value	114,100		114,100
Realized gains or losses on investments	$ 0	$ 0	$ 0	$ 0
Number of investments in unrealized loss position | item	2		2		1
Number of investments in unrealized loss position for more than 12 months | item	0		0		0
Unrealized loss on fair value	$ 11,000		$ 11,000		$ 6,000
Amortized Cost
Schedule of Investments [Line Items]
Total cash, cash equivalents, restricted cash and investments, Amortized Cost	114,329		114,329		147,409
Fair Value
Schedule of Investments [Line Items]
Total cash, cash equivalents, restricted cash and investments, Fair Value	114,368		$ 114,368		$ 147,462
Corporate bonds and commercial paper
Schedule of Investments [Line Items]
Maturity period, investments			1 year		1 year
Corporate bonds and commercial paper | Minimum
Schedule of Investments [Line Items]
Maturity period, investments			1 year		1 year
Corporate bonds and commercial paper | Maximum
Schedule of Investments [Line Items]
Maturity period, investments			5 years		5 years
Corporate bonds and commercial paper | Amortized Cost
Schedule of Investments [Line Items]
Due within 1 year, Amortized Cost	83,118		$ 83,118		$ 73,389
Due between 1 and 5 years, Amortized Cost	5,999		5,999		5,998
Corporate bonds and commercial paper | Fair Value
Schedule of Investments [Line Items]
Due within 1 year, Fair Value	83,163		83,163		73,444
Due between 1 and 5 years, Fair Value	5,992		5,992		5,995
Corporate bonds and commercial paper due within 1 year
Schedule of Investments [Line Items]
Gross Unrealized Gains	47		47		55
Gross Unrealized Losses	(2)		(2)
Corporate bonds and commercial paper due between 1 and 5 years
Schedule of Investments [Line Items]
Gross Unrealized Losses	(7)		(7)		(3)
Investments
Schedule of Investments [Line Items]
Gross Unrealized Gains	47		47		55
Gross Unrealized Losses	(9)		(9)		(3)
Investments | Amortized Cost
Schedule of Investments [Line Items]
Investments, Amortized Cost	89,117		89,117		79,387
Investments | Fair Value
Schedule of Investments [Line Items]
Investments, Fair Value	89,155		89,155		79,439
Cash and money market accounts | Amortized Cost
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Amortized Cost	21,213		21,213		63,024
Cash and money market accounts | Fair Value
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Fair Value	21,213		21,213		63,024
Corporate bonds, agency bonds and commercial paper
Schedule of Investments [Line Items]
Gross Unrealized Gains	1		$ 1		$ 1
Corporate bonds, agency bonds and commercial paper | Maximum
Schedule of Investments [Line Items]
Original maturity period, cash and cash equivalents			90 days		90 days
Corporate bonds, agency bonds and commercial paper | Amortized Cost
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Amortized Cost	3,999		$ 3,999		$ 4,998
Corporate bonds, agency bonds and commercial paper | Fair Value
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Fair Value	4,000		4,000		4,999
Cash and cash equivalents
Schedule of Investments [Line Items]
Gross Unrealized Gains	1		1		1
Cash and cash equivalents | Amortized Cost
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Amortized Cost	25,212		25,212		68,022
Cash and cash equivalents | Fair Value
Schedule of Investments [Line Items]
Cash, cash equivalents & restricted cash, Fair Value	$ 25,213		$ 25,213		$ 68,023

Accrued expenses (Details)

Accrued expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued expenses
Research and development expenses	$ 5,880	$ 5,176
Compensation and related benefits	2,274	5,930
Professional fees	707	615
Consulting fees	551	1,091
Interest	236	236
Commercialization costs	28	330
Other	1,063	1,282
Total accrued expenses	$ 10,739	$ 14,660

Product revenue reserves and _3

Product revenue reserves and allowances (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	$ 121
Credits and payments made	(121)
Trade discounts and allowances
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	23
Credits and payments made	(23)
Government rebates and other incentives
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	67
Credits and payments made	(67)
Returns
Product revenue reserves and allowances
Product revenue reserves and allowances at beginning	31
Credits and payments made	$ (31)

Leases - Leases (Details)

Leases - Leases (Details) - Office and Laboratory Space in Needham, Massachusetts $ in Millions	Feb. 15, 2018USD ($)ft²	Apr. 15, 2014ft²
Leases
Area of space | ft²	27,810	15,197
Minimum
Leases
Operating lease expense	$ 0.7
Maximum
Leases
Operating lease expense	$ 1.1

Leases - Balance sheet and othe

Leases - Balance sheet and other information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Leases
Right-of use asset	$ 2,524		$ 2,524		$ 2,726
Lease liability	3,225		3,225
Lease Expense
Operating lease expense	221	$ 221	442	$ 442
Total Lease Expense	221	221	442	442
Other Information - Operating Leases
Operating cash flows paid for amounts included in measurement of lease liabilities	$ 252	$ 247	$ 504	$ 451
Weighted average remaining lease term (in years)	4 years		4 years
Weighted average discount rate	14.60%		14.60%
Maturity Analysis
2021	$ 514		$ 514
2022	1,039		1,039
2023	1,060		1,060
2024	1,081		1,081
2025	546		546
Total	4,240		4,240
Less: Present value discount	(1,015)		(1,015)
Lease Liability	$ 3,225		$ 3,225

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) $ / shares in Units, $ in Thousands	Nov. 06, 2020USD ($)D$ / shares	Dec. 23, 2019USD ($)D$ / shares	Nov. 14, 2019USD ($)D$ / shares	Oct. 17, 2018USD ($)D$ / shares	Mar. 31, 2021USD ($)shares	Mar. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)shares	Jun. 30, 2021USD ($)$ / shares	Jun. 30, 2020USD ($)	Dec. 31, 2020$ / shares	Nov. 11, 2019$ / shares	Oct. 11, 2018$ / shares
Convertible Notes
Common stock, par value (in dollars per share) | $ / shares								$ 0.0001		$ 0.0001
Other Nonoperating Income (Expenses)									$ (1,313)
Interest make-whole payments on the 2019 Notes									1,763
5.00% Convertible Senior Notes due 2048
Convertible Notes
Aggregate principal amount				$ 150,000
Debt Conversion, Original Debt, Amount		$ 7,400	$ 114,300
Repayments of Convertible Debt		700	11,400
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
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 | D				20
Consecutive trading days | D				30
5.00% Convertible Senior Second Lien Notes due 2048
Convertible Notes
Debt Conversion, Original Debt, Amount					$ 57,400	$ 57,400	$ 57,400
Debt Conversion, Converted Instrument, Amount		$ 4,000	$ 62,900
Interest rate (as a percent)		5.00%	5.00%
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
Conversion premium above the last reported sales price of the Common Stock (as a percent)		52.80%	52.80%
Sale price of the Common Stock | $ / shares											$ 1.08
Percentage of stock price trigger for conversion		121.00%	121.00%
Trading days | D		20	20
Consecutive trading days | D		30	30
Debt discount		$ 200	$ 200
Derivative liability		$ 200	$ 200
Other Nonoperating Income (Expenses)						1,300			$ 1,300
Debt conversion, Converted Instrument, Cash					$ 1,800	$ 1,800	$ 1,800
Debt Conversion, Converted Instrument, Shares Issued | shares					34,796,350	34,796,350	34,796,350
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
Conversion premium above the last reported sales price of the Common Stock (as a percent)	153.90%
Sale price of the Common Stock | $ / shares	$ 1.28
Percentage of stock price trigger for conversion	123.08%
Trading days | D	20
Consecutive trading days | D	30
Percentage price of principal amount to be purchased plus accrued and unpaid interest	100.00%
Change in fair value of conversion option of Notes on exchange	$ 2,300

Common stock (Details)

Common stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 03, 2020	Feb. 27, 2020	Aug. 31, 2017	Mar. 31, 2017	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Subsidiary, Sale of Stock [Line Items]
Proceeds from the issuance of common stock, net							$ 106,069
Common stock
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)					46,511,628
Private Investment in Public Equity (PIPE)
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)		46,511,628
Share price (in dollars per share)		$ 2.15
Share price premium (as percentage)		12.60%
Share price, prior to premium price (in dollars per share)		$ 1.91
Proceeds from the issuance of common stock, net	$ 93,800
At-the-market equity offering program | Common stock
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)						0	6,769,559
Proceeds from the issuance of common stock, net							$ 12,200
Maximum value of common stock allowed to be sold			$ 75,000	$ 35,000
Shares, Outstanding						18,287,913
Net proceeds from issuance of stock						$ 59,600

Stock-based compensation - Stoc

Stock-based compensation - Stock Options (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Shares
Outstanding at the beginning of the period (in shares)	12,690,745
Granted (in shares)	1,098,371
Exercised (in shares)	(487,516)
Forfeited/cancelled (in shares)	(808,975)
Outstanding at the end of the period (in shares)	12,492,625		12,690,745
Vested at the end of the period (in shares)	8,181,296
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 3.90
Granted (in dollars per share)	2.75
Exercised (in dollars per share)	1.52
Forfeited/cancelled (in dollars per share)	3.75
Outstanding at the end of the period (in dollars per share)	3.90		$ 3.90
Vested at the end of the period (in dollars per share)	$ 4.58
Weighted-average remaining contractual term
Outstanding at the end of the period	6 years 2 months 12 days		6 years 6 months
Vested at the end of the period	5 years
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 3,390
Outstanding at the end of the period (in dollars)	18,886		$ 3,390
Vested at the end of the period (in dollars)	$ 11,731
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)	0.66%	0.40%
Volatility (as a percent)	95.00%	97.00%
Dividend yield (as a percent)	0.00%	0.00%
Expected term	5 years 9 months 18 days	5 years 7 months 6 days

Stock-based compensation - Rest

Stock-based compensation - Restricted Stock (Details) - Restricted stock units	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Shares
Unvested at the beginning of the period (in shares) | shares	2,649,317
Granted (in shares) | shares	635,090
Vested (in shares) | shares	(107,390)
Forfeited (in shares) | shares	(243,562)
Unvested at the end of the period (in shares) | shares	2,933,455
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	2.72
Vested (in dollars per share) | $ / shares	2.16
Forfeited/cancelled (in dollars per share) | $ / shares	2.10
Unvested at the end of the period (in dollars per share) | $ / shares	$ 1.90

Stock-based compensation - Empl

Stock-based compensation - Employee Stock Purchase Plan (Details) $ in Thousands	Dec. 18, 2018itemshares	Jun. 30, 2021USD ($)shares	Jun. 30, 2020USD ($)
Assumptions used to estimate fair value of each stock-based award on the grant date
Proceeds from the issuance of common stock, net			$ 106,069
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
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)		0.09%	1.57%
Volatility (as a percent)		65.00%	78.00%
Dividend yield (as a percent)		0.00%	0.00%
Expected term		6 months	6 months
Issuance of common stock under ESPP | shares		53,372
Proceeds from the issuance of common stock, net		$ 100
Employee Stock purchase plan | Maximum
Assumptions used to estimate fair value of each stock-based award on the grant date
Stock-based compensation expense		$ 100	$ 100

Net loss per share (Details)

Net loss per share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	24,140,025	18,957,387	24,140,025	18,957,387
Stock options
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	12,492,625	13,400,155	12,492,625	13,400,155
Restricted stock units
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	2,933,455	1,476,148	2,933,455	1,476,148
2018 Notes
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	41,873	3,950,032	41,873	3,950,032
2020 Notes
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	8,615,384		8,615,384
Employee Stock Purchase Plan
Net loss per share
Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	56,688	131,052	56,688	131,052

License, collaboration and co_3

License, collaboration and commercial agreements - Secura Bio Inc (Details) $ in Thousands	Jul. 25, 2019USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)Milestone	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)Milestone	Jun. 30, 2020USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 500		$ 4,307	$ 1,506	$ 9,363
Copiktra license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			52			902
Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			448			604
License and Collaboration Agreement | Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment		$ 70,000
Regulatory milestone payments				$ 800
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%
Term of agreement		1 year
Number of days written prior notice required for other party to terminate agreement		5 days
Future potential royalties expected to be received			100			100
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			800			800
Revenue recognized			100			$ 900
Number of regulatory milestone achieved | Milestone						1
License and Collaboration Agreement | Secura | Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 400			$ 600
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 | Sanofi
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 42,000
Number of regulatory milestone achieved | Milestone				1

License, collaboration and co_4

License, collaboration and commercial agreements - Secura - Contract asset (Details) - License and Collaboration Agreement $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additions	$ 152
Reclassification to receivable	(22)
Balance at the end of period	130
Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Additions	152
Reclassification to receivable	(22)
Balance at the end of period	130
Prepaid Expenses and Other Current Assets | Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Balance at the end of period	$ 100

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	Mar. 31, 2021
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 expense.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
One-time cash payment		$ 3

License, collaboration and co_6

License, collaboration and commercial agreements - Sanofi (Details) - License and Collaboration Agreement - Sanofi - USD ($) $ in Millions	Jul. 25, 2019	Aug. 31, 2019	Jun. 30, 2021
License and collaboration agreements
Proceeds received		$ 5
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 42
Percentage of future milestone payments and royalties entitled			50.00%

License, collaboration and co_7

License, collaboration and commercial agreements - Yakult (Details) - License and Collaboration Agreement - Yakult - USD ($) $ in Millions	Jun. 05, 2018	Jun. 30, 2018	Jun. 30, 2021
License and collaboration agreements
Proceeds received		$ 10
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 90
Percentage of future milestone payments and royalties entitled			50.00%

License, collaboration and co_8

License, collaboration and commercial agreements - CSPC (Details) - License and Collaboration Agreement - CSPC - USD ($) $ in Millions	Sep. 25, 2018	Jun. 30, 2021
License and collaboration agreements
Upfront, non-refundable payment obligation to be received prior to initial Exclusivity Fee	$ 15
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 160
Percentage of future milestone payments and royalties entitled		50.00%

Restructurings (Details)

Restructurings (Details) $ in Millions	Feb. 27, 2020position	Aug. 31, 2020position	Jun. 30, 2020USD ($)	Jun. 30, 2020USD ($)
Restructuring Costs
Restructuring costs			$ 0	$ 1.8
Selling, general and administrative expenses
Restructuring Costs
Restructuring costs			0	1.4
Research and development expense.
Restructuring Costs
Restructuring costs			$ 0	$ 0.4
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	6 Months Ended
	Jun. 30, 2021USD ($)
Restructuring Cost and Reserve [Line Items]
Amounts accrued at, December 31, 2020	$ 1,027
Charges	0
Amount Paid	(1,014)
Adjustments	0
Amounts accrued at, June 30, 2021	13
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	(1,014)
Adjustments	0
Amounts accrued at, June 30, 2021	$ 13

Subsequent events (Details)

Subsequent events (Details) - USD ($) $ in Thousands	Jul. 16, 2021	Jun. 30, 2021	Dec. 31, 2020	Nov. 06, 2020
Subsequent Event [Line Items]
Amount outstanding convertible senior notes		$ 20,326	$ 19,051
5.00% Convertible Senior Third Lien Notes due 2048
Subsequent Event [Line Items]
Aggregate principal amount				$ 28,000
Subsequent event | 5.00% Convertible Senior Third Lien Notes due 2048
Subsequent Event [Line Items]
Aggregate principal amount	$ 28,000
Debt Conversion, Converted Instrument, Amount	$ 28,000
Debt Conversion, Converted Instrument, Shares Issued	8,615,384
Amount outstanding convertible senior notes	$ 0