Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
OPERATING ACTIVITIES
Net loss	$ (16,429)	$ (5,493)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	6,039	579
Depreciation and amortization	482	277
Net amortization of premium on available-for-sale securities	152	46
Changes in operating assets and liabilities:
Other receivables	(249)	(112)
Other receivables - related parties	(2)	0
Prepaid expenses and other current assets	(2,589)	(106)
Inventory	(990)	0
Other assets	30	(79)
Accounts payable	(234)	481
Deferred revenue	6	0
Deferred rent	(15)	166
Accrued expenses	(1,414)	(885)
Accrued research and development	424	52
Other noncurrent liabilities	(83)	0
Net cash used in operating activities	(14,872)	(5,074)
INVESTING ACTIVITIES
Purchases of property and equipment	(838)	(1,063)
Purchase of available-for-sale securities	(30,279)	(3,485)
Proceeds from maturities of available-for-sale securities	43,000	7,500
Net cash provided by investing activities	11,883	2,952
FINANCING ACTIVITIES
Proceeds from issuance of common stock upon follow-on public offering, net of issuance costs	103,595	0
Proceeds from return of profit	11,403	0
Repurchase of Class A common stock	(2)	0
Proceeds from stock option exercises including early exercised options	171	45
Net cash provided by financing activities	115,167	45
Net increase (decrease) in cash, cash equivalents and restricted cash	112,178	(2,077)
Cash, cash equivalents and restricted cash, beginning of period	333,928	17,828
Cash, cash equivalents and restricted cash, end of period	446,106	15,751
Accounts Payable
FINANCING ACTIVITIES
Property and equipment purchases included in balance sheet locations	9	2,424
Offering costs in accounts payable	158	0
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases included in balance sheet locations	9	2,424
Offering costs in accounts payable	158	0
Accrued Liabilities
FINANCING ACTIVITIES
Property and equipment purchases included in balance sheet locations	49	0
Offering costs in accounts payable	478	0
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases included in balance sheet locations	49	0
Offering costs in accounts payable	$ 478	$ 0