Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net loss	$ (78,608)	$ (49,458)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	260	90
Non-cash lease expense	975
Premium amortization and discount accretion on marketable securities, net	(216)	220
Stock-based compensation expense, including employee stock purchase plan expense	13,968	11,286
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	61	1,232
Other assets	(1,114)
Accounts payable	(9)	(527)
Other current liabilities	3,281	5,070
Operating lease liabilities	(952)
Net cash used in operating activities	(62,354)	(32,087)
Cash flows from investing activities:
Purchase of equipment	(190)	(876)
Maturities of marketable securities	244,500	186,449
Purchases of marketable securities	(169,167)	(467,011)
Net cash provided by (used in) investing activities	75,143	(281,438)
Cash flows from financing activities:
Proceeds from exercise of stock options	146	187
Proceeds from issuance of common stock under employee stock purchase plan	57	386
Net cash provided by financing activities	203	573
Net increase (decrease) in cash and cash equivalents	12,992	(312,952)
Cash and cash equivalents at beginning of period	13,812	338,549
Cash and cash equivalents at end of period	26,804	25,597
Supplemental disclosure of non-cash investing and financing activities:
Reclassification of prepaid expenses and other current liabilities into other assets	1,117
Vesting of early exercised stock options	$ 93	341
Purchases of property and equipment included in accounts payable		$ 114