Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (168,099)	$ (149,291)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	15,178	17,542
Depreciation and amortization expense	1,683	1,088
Amortization (accretion) of premium (discount) on marketable securities	1,276	2,580
Loss on sale of marketable securities	34	8
Non-cash lease expense	1,662	(746)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(4,144)	(1,506)
Right-of-use assets	0	(2,940)
Accounts payable and other liabilities	(1,235)	13,702
Net cash used in operating activities	(153,645)	(119,563)
Cash flows from investing activities:
Purchases of property and equipment	(3,067)	(3,618)
Purchases of marketable securities	(121,176)	(236,721)
Maturities of marketable securities	208,291	98,010
Sales of marketable securities	3,154	4,437
Net cash used in investing activities	87,202	(137,892)
Cash flows from financing activities:
Proceeds from follow-on public offering of common stock, net of issuance costs	36,861	157,237
Proceeds from exercise of stock options	529	584
Net cash provided by financing activities	37,390	157,821
Net increase (decrease) in cash, cash equivalents and restricted cash	(29,053)	(99,634)
Cash, cash equivalents and restricted cash, beginning of year	203,519	303,153
Cash, cash equivalents and restricted cash, end of year	174,466	203,519
Supplemental disclosure of non-cash investing and financing information:
Purchase of property and equipment in accounts payable	85	202
Right-of-use assets acquired under operating leases	$ 0	$ 34,228