Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Net loss	$ (54,424)	$ (23,995)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	8,255	6,145
Vesting of common stock warrants	44	44
Change in fair value of derivative liability	8	85
Depreciation and amortization	872	753
Amortization of right-of-use assets	741	737
Net amortization (accretion) of premium (discount) on marketable securities	1,051	0
Changes in operating assets and liabilities
Accounts receivable	47	268
Prepaid expenses and other current assets	2,660	653
Accounts payable	(1,454)	(172)
Accrued and other liabilities	(422)	(904)
Deferred revenue	(1,382)	(14,454)
Operating lease liabilities	550	(737)
Net cash used in operating activities	(43,454)	(31,577)
Cash flows from investing activities
Purchase of marketable securities	(65,879)	0
Maturities of marketable securities	77,716	0
Acquisition of property and equipment	(8,479)	(1,379)
Net cash provided by (used in) investing activities	3,358	(1,379)
Cash flows from financing activities
Payment of offering costs	(360)	(946)
Proceeds from the exercise of stock options and warrants	939	919
Net cash provided by (used in) financing activities	579	(27)
Net decrease in cash and cash equivalents	(39,517)	(32,983)
Cash and cash equivalents, beginning of period	153,001	276,726
Cash and cash equivalents, end of period	113,484	243,743
Supplemental disclosures of noncash investing and financing information
Decrease in right-of-use assets due to reduction in operating lease liabilities upon modification	0	(478)
Issuance of common stock warrant to settle liability	0	1,146
Purchases of property and equipment in accounts payable and accrued and other liabilities	$ 1,298	$ 347