CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities
Net loss	$ (54,719)	$ (47,862)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	176	450
Amortization of acquired intangible asset		793
Amortization of right-of-use asset and lease liability	(98)	(38)
Stock-based compensation expense	6,137	5,185
Amortization of deferred financing costs, debt discounts and premiums and discounts on available-for-sale marketable securities	9,287	9,765
Change in fair value of interest make whole provision for 2019 Notes		1,313
Changes in operating assets and liabilities:
Accounts receivable, net	134	(3,161)
Inventory		3,096
Prepaid expenses, other current assets and other assets	(1,834)	1,084
Accounts payable	(1,038)	(4,974)
Accrued expenses and other liabilities	(1,614)	3,951
Other long-term liabilities		(870)
Intangible assets & property, plant and equipment		19,465
Net cash used in operating activities	(43,569)	(11,803)
Investing activities
Purchases of property and equipment	(196)	(33)
Purchases of investments	(53,258)
Maturities of investments	53,475	32,050
Net cash provided by investing activities	21	32,017
Financing activities
Proceeds from the exercise of stock options and employee stock purchase program	1,079	1,940
Interest make-whole payments on the 2019 Notes		(1,763)
Payment of deferred offering costs	(73)
Settlement of restricted stock for tax withholdings	(926)
Proceeds from the issuance of common stock, net		106,059
Net cash provided by financing activities	80	106,236
(Decrease) increase in cash, cash equivalents and restricted cash	(43,468)	126,450
Cash, cash equivalents and restricted cash at beginning of period	68,023	79,262
Cash, cash equivalents and restricted cash at end of period	24,555	205,712
Supplemental disclosure of non-cash investing and financing activities
Common stock issuance costs included in accounts payable and accrued expenses		15
Purchases of property and equipment included in accounts payable and accrued expenses		217
Deferred offering costs included in accounts payable and accrued expenses	46
Settlement of restricted stock units for tax withholdings included in accrued expenses		124
5.00% Convertible Senior Second Lien Notes due 2048
Supplemental disclosure of non-cash investing and financing activities
Conversion of 2019 Notes and 2020 Notes into common stock		$ 57,414
5.00% Convertible Senior Third Lien Notes due 2048
Supplemental disclosure of non-cash investing and financing activities
Conversion of 2019 Notes and 2020 Notes into common stock	$ 28,000