Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (32,094)	$ (34,999)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,266	6,066
Depreciation and amortization expense	1,330	1,197
Amortization (accretion) of premium (discount) on marketable securities, net	(2,101)	0
Loss on sale of property and equipment	24	28
Changes in operating assets and liabilities:
Collaboration receivable	(47,500)	0
Tenant receivable	(1,419)	0
Prepaid expenses and other current assets	761	(531)
Operating lease right-of-use assets	1,263	2,260
Other noncurrent assets	1,115	(5,176)
Accounts payable	816	(684)
Accrued expenses and other current liabilities	(4,292)	(3,407)
Deferred revenue	47,500	0
Operating lease liability	654	(189)
Net cash used in operating activities	(27,677)	(35,435)
Cash flows from investing activities:
Purchases of property and equipment	(755)	(2,784)
Purchases of marketable securities	(87,861)	0
Maturities of marketable securities	83,000	0
Net cash used in investing activities	(5,616)	(2,784)
Cash flows from financing activities:
Payment of share issuance costs	(29)	(50)
Proceeds from issuance of common stock in connection with the Moderna Agreement	36,000	0
Proceeds from exercise of stock options and other types of equity, net	0	102
Tax withholding payments related to net share settlements of restricted stock units	(199)	0
Net cash provided by financing activities	35,772	52
Net increase (decrease) in cash, cash equivalents and restricted cash	2,479	(38,167)
Cash, cash equivalents and restricted cash at beginning of period	98,863	380,837
Cash, cash equivalents and restricted cash at end of period	101,342	342,670
Supplemental disclosure of noncash investing and financing information:
Purchases of property and equipment included in accounts payable and accrued expenses	438	1,928
Unrealized gains on marketable securities	117	0
Issuance costs included in accrued expenses	$ 149	$ 0