Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net loss	$ (41,399)	$ (57,414)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	177	235
Net amortization of premiums and discounts on investments	45	664
Amortization of debt discount and issuance costs	198	191
Stock-based compensation expense	7,336	7,359
Realized and unrealized gain on marketable equity securities	(2)	(14)
Inventory obsolescence charge	0	82
Changes in operating assets and liabilities:
Accounts receivable	(2,495)	(4,962)
Inventory	232	(552)
Prepaid expenses and other current assets	(27,303)	(89)
Operating lease right-of-use assets	397	343
Other noncurrent assets	11,703	0
Accounts payable	1,837	(1,410)
Accrued expenses and other liabilities	(9,387)	3,432
Deferred revenue	0	(297)
Operating lease liabilities	(536)	(456)
Net cash used in operating activities	(59,197)	(52,888)
Investing activities
Purchases of property and equipment	(79)	0
Proceeds from sales and maturities of investments	21,584	68,950
Purchases of investments	(35,540)	(25,764)
Net cash (used in) provided by investing activities	(14,035)	43,186
Financing activities
Proceeds from issuance of common stock, net of issuance costs	29,316	9,903
Proceeds from the exercise of stock options and shares issued under employee stock purchase plan	1,467	773
Net cash provided by financing activities	30,783	10,676
Effect of exchange rate on cash, cash equivalents and restricted cash	(90)	(91)
Net (decrease) increase in cash, cash equivalents and restricted cash	(42,539)	883
Cash, cash equivalents and restricted cash at beginning of period	197,445	89,121
Cash, cash equivalents and restricted cash at end of period	154,906	90,004
Reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets
Cash and cash equivalents	153,256	88,471
Short-term restricted cash	1,014	815
Long-term restricted cash	636	718
Total cash, cash equivalents and restricted cash	154,906	90,004
Supplemental disclosures:
Deferred financing costs in accrued expenses	22	0
Cash paid for amounts included in the measurement of operating lease liabilities	841	815
Cash paid for interest on deferred royalty obligation	$ 15,784	$ 2,457