Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (87,887)	$ (54,923)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	7,519	7,891
Depreciation and amortization expense	885	487
Non-cash lease expense	2,183	(15)
Amortization of premium on marketable securities	1,011	1,146
Loss on sale of marketable securities	21	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(656)	(21,393)
Other assets	0	(578)
Accounts payable and other liabilities	(4,724)	2,842
Net cash used in operating activities	(81,648)	(64,543)
Cash flows from investing activities:
Purchases of property and equipment	(1,662)	(747)
Purchases of marketable securities	(89,530)	(156,562)
Maturities of marketable securities	104,740	22,500
Sales of marketable securities	2,759	0
Net cash provided by (used in) investing activities	16,307	(134,809)
Cash flows from financing activities:
Proceeds from follow-on public offering of common stock, net of issuance costs	0	157,237
Proceeds from exercise of stock options	117	38
Net cash provided by financing activities	117	157,275
Net decrease in cash and cash equivalents	(65,224)	(42,077)
Cash, cash equivalents and restricted cash, beginning of period	203,519	303,153
Cash, cash equivalents and restricted cash, end of period	138,295	261,076
Supplemental disclosures of cash flow information:
Purchase of property and equipment in accounts payable	$ 230	$ 383