CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating Activities:
Net loss	$ (101,093)	$ (84,019)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	2,467	2,200
Deferred revenue	(3,903)
Non-cash loss on contract termination	5,687
Loss on disposal of property and equipment	205	5
Stock-based compensation	10,101	8,204
Accretion of discount on issued term debt	405	332
Accretion of investment discount, net	(97)	114
Changes in operating assets and liabilities:
Accounts receivable	(232)
Prepaid expenses and other current assets	1,017	1,733
Operating lease right-of-use assets	2,262	1,817
Other long-term assets	610	(208)
Accounts payable	(5,859)	3,727
Accrued expenses and other liabilities	(205)	(2,694)
Operating lease liabilities	(2,418)	(1,355)
Net cash used in operating activities	(91,053)	(70,144)
Investing Activities:
Purchases of property and equipment	(1,961)	(2,056)
Purchases of short-term investments	(79,611)
Proceeds from maturities of short-term investments		187,500
Net cash provided by (used in) investing activities	(81,572)	185,444
Financing Activities:
Net proceeds from issuance of common stock under employee stock compensation plans	713	427
Payment of debt issuance costs	(1,450)
Proceeds from term debt	30,000
Net cash provided by financing activities	29,263	427
Net increase (decrease) in cash and cash equivalents	(143,362)	115,727
Cash and cash equivalents at beginning of period	206,325	83,966
Cash and cash equivalents at end of period	62,963	199,693
Non-cash operating, investing and financing activities:
Purchases of property and equipment in accounts payable and accrued liabilities	1,429	109
Supplemental disclosure of cash flow information:
Interest paid	$ 1,996	$ 1,356