Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (41,502)	$ (28,278)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,993	1,151
Loss on disposal of fixed asset	(1)
Depreciation expense	238	105
Amortization of premium on marketable securities	(12)	11
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,085	(1,840)
Accounts payable	(877)	(4,193)
Accrued expenses	2,123	713
Right-of-use assets	396	247
Operating lease liabilities	(378)	(281)
Other assets	(252)	23
Net cash used in operating activities:	(34,187)	(32,342)
Cash flows from investing activities:
Purchase of property and equipment	(324)	(63)
Purchase of marketable debt securities	(8,247)
Maturities and sales of marketable debt securities	26,250
Cash, cash equivalents, and restricted cash acquired in connection with the Merger		41,934
Merger transaction costs		(1,236)
Net cash provided by investing activities	17,679	40,635
Cash flows from financing activities:
Capital contribution from related party		17,995
Proceeds from issuance of equity securities, net of issuance costs	19,885	75,350
Net cash provided by financing activities	19,885	93,345
Net increase in cash, cash equivalents and restricted cash	3,377	101,638
Cash, cash equivalents and restricted cash at beginning of period	69,487	1,009
Cash, cash equivalents and restricted cash at end of period	72,864	102,647
Supplemental disclosure of non-cash investing and financing activities:
Fair value of net assets acquired in the Merger, including $1.0 million of marketable debt securities and excluding cash acquired		(4,815)
Property and equipment included in accounts payable and accrued expenses	$ 9
Merger transaction costs included in accounts payable and accrued expenses		60
Leased assets obtained in exchange for new operating lease liabilities		$ 448