Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net loss	$ (15,323)	$ (170,084)
Reconciliation of net loss to net cash used in operating activities:
Non-cash portion of acquired in-process research and development		164,612
Stock-based compensation expense	1,209	366
Expense for warrants inherited in acquisition of Quellis	1,542	55
Other non-cash items	(79)	4
Changes in assets and liabilities:
Prepaid expenses and other assets	163	767
Right-of-use asset-operating	(15)	(73)
Accounts payable	(627)	(1,712)
Accrued expenses	571	(2,651)
Net cash used in operating activities	(12,559)	(8,716)
Investing activities
Purchases of short-term investments	(81,702)
Sales and maturities of short-term investments	54,603	20,000
Cash acquired in acquisition of Quellis		6,466
Purchases of property and equipment		(21)
Net cash (used in) provided by investing activities	(27,099)	26,445
Financing activities
Net cash provided by financing activities		104,261
Net (decrease) increase in cash, cash equivalents and restricted cash	(39,658)	121,990
Cash, cash equivalents and restricted cash, beginning of period	86,629	25,051
Cash, cash equivalents and restricted cash, end of period	$ 46,971	$ 147,041