Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash Flows from Operating Activities
Net loss	$ (40,196)	$ (52,753)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,566	2,719
Amortization of operating right-of-use asset	891	785
Stock-based compensation	6,086	9,824
Amortization of discount or premium on available-for-sale securities	(191)	118
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	4,701	(2,995)
Accounts payable	(586)	(1,298)
Accrued expenses	(3,776)	(3,692)
Other current liabilities	(206)	(59)
Operating lease liabilities	(1,717)	(1,577)
Net cash used in operating activities	(32,428)	(48,928)
Cash Flows from Investing Activities
Purchase of property and equipment	(101)	(496)
Purchase of investments	(14,699)	(51,585)
Proceeds from maturities of investments	43,985	28,951
Net cash provided (used in) by investing activities	29,185	(23,130)
Cash Flows from Financing Activities
Proceeds from the issuance of Class A common stock under the Employee Stock Purchase Plan	110	177
Proceeds from exercise of stock options		76
Proceeds from issuance of common shares in "at-the-market" equity offering, net of issuance costs		3,509
Principal payments on capital lease obligations		(4)
Net cash provided by financing activities	110	3,758
Net change in cash, cash equivalents and restricted cash	(3,133)	(68,300)
Cash, cash equivalents and restricted cash, beginning of period	31,934	96,204
Cash, cash equivalents and restricted cash, end of period	28,801	27,904
Supplemental Schedule of Non-Cash Investing and Financing Activities
Purchases of property and equipment included in accounts payable and accrued liabilities	69	$ 42
Reclassification of fixed assets held-for-sale	$ 78