CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (52,412)	$ (42,330)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	8,260	8,642
Depreciation and amortization expense	1,559	1,496
Amortization (accretion) of premium (discount) on investments	(25)	61
Non-cash interest expense	204	693
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	287	(384)
Operating lease, right-of-use-asset	1,248	1,347
Accounts payable	124	(757)
Accrued expenses and other current liabilities	(5,200)	(6,325)
Other long-term liabilities	(34)	(34)
Operating lease liabilities	(1,146)	(1,148)
Net cash used in operating activities	(47,135)	(38,739)
Cash flows from investing activities:
Purchases of property, plant and equipment	(2,402)	(748)
Purchases of investments	(78,445)
Sales and maturities of investments		42,500
Net cash provided by (used in) investing activities	(80,847)	41,752
Cash flows from financing activities:
Proceeds from underwritten public offering of common stock, net of commissions and underwriting discounts		188,000
Proceeds from issuance of common stock upon exercise of stock options	76	5,908
Net cash provided by financing activities	76	193,908
Net increase (decrease) in cash, cash equivalents and restricted cash	(127,906)	196,921
Cash, cash equivalents and restricted cash at beginning of period	227,583	92,901
Cash, cash equivalents and restricted cash at end of period	99,677	289,822
Supplemental cash flow information:
Cash paid for interest	1,425	1,054
Cash paid for leases	1,823	1,901
Supplemental disclosure of non-cash investing and financing information:
Purchases of property, plant and equipment included in accounts payable or accrued expenses	$ 1,257	408
Offering costs included in accounts payable and accrued expenses		$ 494