Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (23,844)	$ (6,085)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	108	83
Stock-based compensation expense	3,701	449
Amortization of premiums and discounts on marketable securities, net	40	0
Amortization of discounts and loan issuance costs	0	9
Gain on disposal of property and equipment	(16)	0
Noncash interest expense	0	38
Changes in operating assets and liabilities:
Prepaid and other assets	(491)	(406)
Accounts payable and accrued liabilities	2,390	96
Accrued compensation	(407)	(673)
Operating lease right-of-use assets and liabilities, net	150	(31)
Deferred revenue	(1,312)	(620)
Net cash used in operating activities	(19,681)	(7,140)
Cash flows from investing activities
Purchases of property and equipment	(525)	(10)
Net cash used in investing activities	(525)	(10)
Cash flows from financing activities
Proceeds from exercise of stock options, net of repurchases	17	16
Payments on long-term debt	0	(700)
Proceeds from issuance of Series C convertible preferred stock, net of issuance costs	0	2,200
Payment of deferred financing costs	0	(193)
Net cash provided by financing activities	17	1,323
Net decrease in cash, cash equivalents and restricted cash	(20,189)	(5,827)
Cash, cash equivalents and restricted cash at beginning of period	321,713	94,578
Cash, cash equivalents and restricted cash at end of period	301,524	88,751
Supplemental disclosure of cash flow information:
Cash paid for interest	0	50
Supplemental schedule of noncash investing and financing activities:
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	286	0
Costs incurred, but not paid, in connection with deferred financing costs included in accounts payable and accrued liabilities	0	1,139
Receivables from stock option exercises included in prepaid and other assets	$ 7	$ 0