STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (69,389)	$ (36,603)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and other	7,196	3,413
Stock-based compensation	10,288	7,911
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(4,889)	559
Accounts payable	(1,959)	2,040
Accrued liabilities	(178)	(244)
Deferred rent	1,687	348
Deferred revenue		(22,378)
Net cash used in operating activities	(57,244)	(44,954)
Cash flows from investing activities:
Maturities of marketable securities	195,438	187,784
Purchases of marketable securities	(156,477)	(137,129)
Purchase of property and equipment	(2,360)	(7,132)
Net cash provided by investing activities	36,601	43,523
Cash flows from financing activities:
Proceeds from exercise of stock options	208	112
Payments of the term loan	(3,473)	(1,527)
Net cash used in financing activities	(3,265)	(1,415)
Net decrease in cash, cash equivalents and restricted cash	(23,908)	(2,846)
Cash, cash equivalents and restricted cash - beginning of period	36,284	39,130
Cash, cash equivalents and restricted cash - end of period	12,376	36,284
Supplemental disclosures of cash flow information:
Cash paid for interest	$ 162	130
Supplemental disclosures of noncash investing and financing activities:
Purchase of property and equipment included in accrued liabilities		$ 109