Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (44,671)	$ (38,031)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	9,830	10,700
Depreciation expense	1,415	1,303
Non-cash lease expense	1,262	421
Non-cash interest expense	443	16
Loss on disposal of assets	0	16
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,636	1,248
Accounts payable	797	(2,355)
Deferred revenue	0	(14,068)
Lease liabilities	(912)	374
Accrued expenses	(621)	(2,772)
Net cash used in operating activities	(30,821)	(43,148)
Cash flows from investing activities:
Purchases of property and equipment	(16)	(2,542)
Purchase of marketable securities	(38,108)	(43,023)
Redemption of marketable securities	31,483	2,500
Net cash used in investing activities	(6,641)	(43,065)
Cash flows from financing activities:
Proceeds from issuance of common stock, net	61	900
Proceeds from Employee Stock Purchase Plan	139	0
Net cash provided by financing activities	200	900
Net decrease in cash, cash equivalents and restricted cash	(37,262)	(85,313)
Cash, cash equivalents, and restricted cash at beginning of period	81,334	222,161
Cash, cash equivalents, and restricted cash at end of period	44,072	136,848
Non-cash items:
Purchases of property and equipment included in accrued expenses	0	12
Purchases of property and equipment and right of use assets in accounts payable	$ 0	$ 760