Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Net loss	$ (114,251)	$ (117,473)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	912	842
Stock-based compensation expense	20,982	16,762
In process research and development expenses	35	45
Amortization of operating lease right-of-use assets	1,284	1,729
Amortization of long-term debt discount and issuance costs	591	3,284
Amortization of premium on marketable securities, net of accretion of discounts	145	115
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(4,023)	(1,373)
Other assets	(174)	(43)
Operating lease liabilities	(1,350)	(1,778)
Accounts payable	1,204	(6,631)
Accrued expenses	(2,531)	(342)
Accrued research and development expenses	(1,935)	2,775
Accrued compensation and benefits	(3,186)	(4,258)
Accrued interest expense	(8)	0
Net cash used in operating activities	(102,305)	(106,346)
Cash flows from investing activities
Research and development asset acquisitions, net of cash acquired	(35)	(45)
Purchase of marketable securities	(72,589)	(49,923)
Maturities of marketable securities	86,000	12,800
Purchase of property and equipment	(277)	(940)
Net cash provided by (used in) investing activities	13,099	(38,108)
Cash flows from financing activities
Proceeds from issuance of common stock pursuant to Employee Stock Purchase Plan	595	759
Proceeds from the exercise of stock options	147	286
Net cash provided by financing activities	742	1,045
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(687)	(192)
Net decrease in cash, cash equivalents and restricted cash	(89,151)	(143,601)
Cash, cash equivalents and restricted cash, at the beginning of the period	183,467	486,620
Cash, cash equivalents and restricted cash, at the end of the period	94,316	343,019
Supplemental disclosure of cash flow information:
Cash paid for interest	6,365	6,365
Supplemental disclosure of noncash investing and financing activities:
Operating lease right-of-use asset obtained in exchange for lease liability	3,029	0
Change in unrealized loss on marketable securities, net	$ (413)	$ (115)