Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net loss	$ (70,091)	$ (99,729)
Adjustment to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	9,291	10,661
Depreciation expense	382	82
Amortization of premium on investments	456	1,814
Noncash rent expense	2,049	1,331
Other non-cash items	0	(15)
Loss on disposal of property and equipment	8	3
Changes in current assets and liabilities:
Prepaid expenses and other current assets	(880)	(2,163)
Other non-current assets	16	7
Accounts payable	1,653	2,263
Accrued expenses and other current liabilities	(3,929)	10,692
Non-current operating lease liabilities	(2,098)	(1,048)
Net cash used in operating activities	(63,143)	(76,102)
Cash flows from investing activities:
Purchases of equipment	(192)	(2,377)
Proceeds from sales and maturities of investments	87,690	134,331
Purchases of investments	(36,454)	(44,583)
Net cash provided by investing activities	51,044	87,371
Cash flows from financing activities:
Proceeds from exercise of common stock options and ESPP	205	729
Net cash provided by financing activities	205	729
Net (decrease) increase in cash and cash equivalents	(11,894)	11,998
Cash, cash equivalents and restricted cash, beginning of period	67,022	35,828
Cash, cash equivalents and restricted cash, end of period	55,128	47,826
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Cash and cash equivalents	53,960	46,603
Restricted cash	1,168	1,223
Cash, cash equivalents and restricted cash, end of period	55,128	47,826
Supplemental disclosure of non-cash investing and financing activities:
Purchases of equipment included in accounts payable and accrued expenses	0	216
Right-of-use assets obtained in exchange for operating lease obligation	(117)	21,484
Right-of-use asset derecognized upon early lease termination	$ 0	$ 476