CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (95,764)	$ (128,694)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	8,353	7,965
Noncash lease expense	1,191	939
Stock-based compensation expense	17,245	13,248
Amortization of premium (accretion of discount) on short-term investments	894	(198)
Loss on disposal of property and equipment	133	888
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(4,996)	2,056
Accounts payable	(2,487)	2,459
Accrued expenses and other liabilities	1,500	2,432
Deferred revenue	(33,411)	6,824
Operating lease liabilities	(2,409)	(2,251)
Net cash used in operating activities	(109,751)	(94,332)
Cash flows from investing activities:
Purchases of short-term investments	(97,392)	(19,991)
Maturities of short-term investments	49,000	228,620
Purchases of property and equipment	(2,396)	(3,733)
Net cash provided by (used in) investing activities	(50,788)	204,896
Cash flows from financing activities:
Proceeds from issuance of common stock in follow-on public offering, net of discounts and issuance costs	49,744
Proceeds From Issuance Of Common Stock Pursuant To ATM Financing Net Of Discounts And Issuance Costs	1,454
Proceeds from issuance of common stock in private placement		51,979
Proceeds from issuance of common stock from option exercises	145	176
Proceeds from issuance of common stock pursuant to employee stock purchase plan	826	938
Net cash provided by financing activities	52,169	53,093
Net change in cash, cash equivalents and restricted cash	(108,370)	163,657
Cash, cash equivalents and restricted cash, beginning of period	218,705	55,048
Cash, cash equivalents and restricted cash, end of period	110,335	218,705
Supplemental disclosures of noncash investing and financing activities:
Reclassification of liability for common stock vested	13	24
Property and equipment additions included in accounts payable	241	110
Property and equipment additions included in accrued expenses and other liabilities	116
Unrealized (loss) gain on available for sale securities, net	$ (7)	$ (183)