Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (125,596)	$ (67,254)
Adjustment to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	14,037	7,765
Depreciation expense	205	52
Amortization of premium on investments	2,186	1,725
Noncash rent expense	2,012	548
Gain on sale of investments	(10)	(24)
Other non-cash items	(5)	0
Loss on disposal of property and equipment	3	0
Changes in current assets and liabilities:
Prepaid expenses and other current assets	(1,628)	(3,439)
Other non-current assets	90	(47)
Accounts payable	1,569	1,069
Accrued expenses and other current liabilities	8,714	8,026
Non-current operating lease liability	(1,725)	(567)
Net cash used in operating activities	(100,148)	(52,146)
Cash flows from investing activities:
Purchases of equipment	(2,710)	(142)
Proceeds from sales and maturities of investments	182,831	90,928
Purchases of investments	(49,508)	(372,477)
Net cash used in investing activities	130,613	(281,691)
Cash flows from financing activities:
Proceeds from exercise of common stock options and ESPP	729	1,100
Proceeds from initial public offering, net of issuance costs of $1,275	0	213,844
Net cash provided by financing activities	729	214,944
Net increase (decrease) in cash and cash equivalents	31,194	(118,893)
Cash, cash equivalents and restricted cash, beginning of year	35,828	154,721
Cash, cash equivalents and restricted cash, end of year	67,022	35,828
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Cash and cash equivalents	65,799	34,605
Restricted cash, end of year	1,223	1,223
Cash, cash equivalents and restricted cash, end of year	67,022	35,828
Supplemental disclosure of non-cash investing and financing activities:
Conversion of preferred stock into common stock upon closing of initial public offering	0	200,573
Right-of-use assets obtained in exchange for operating lease obligation	21,505	8,474
Right-of-use asset derecognized upon early lease termination	$ 476	$ 0