Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (41,533)	$ (631)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,310	1,113
Stock-based compensation expense	3,895	1,829
Other losses	266	0
Changes in operating assets and liabilities:
Tax credit receivable	250	167
Accounts receivable	(2,227)	(7,052)
Prepaid expenses and other current assets	(2,756)	(1,458)
Other non-current assets	(70)	232
Accounts payable	922	(1,255)
Accrued liabilities	2,689	4,255
Deferred rent and other long-term liabilities	(17)	50
Net cash used in operating activities	(37,271)	(2,750)
Cash flows from investing activities:
Purchase of short-term investments	(322,605)	(51,713)
Accretion on short-term investments	0	(254)
Maturity of short-term investments	113,271	35,000
Purchase of property and equipment	(1,532)	(964)
Net cash used in investing activities	(210,866)	(17,931)
Cash flows from financing activities:
Proceeds from issuance of common stock upon initial public offering, net of issuance costs	150,751	0
Proceeds from issuance of common stock upon completion of private placement	10,000	0
Proceeds from issuance of Series C preferred stock, net of issuance costs	52,019	47,947
Proceeds from exercise of stock options	442	174
Payment of deferred offering costs	0	(2,582)
Net cash provided by financing activities	213,212	45,539
Net (decrease) increase in cash and cash equivalents	(34,925)	24,858
Cash and cash equivalents at beginning of period	85,807	60,949
Cash and cash equivalents at end of period	50,882	85,807
Supplemental disclosures of noncash investing and financing activities:
Purchase of property and equipment in accounts payable and accrued liabilities	188	159
Reclassification of restricted stock awards from liabilities to common stock upon vesting	11	30
Accretion to redemption value and dividends on redeemable convertible preferred stock	0	6,225
Deferred offering costs in accounts payable and accrued liabilities	0	230
Net unrealized loss on short-term investments	$ (31)	$ (1)