CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income (loss)	$ 2,859	$ (69,987)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation expense	2,105	1,369
Stock‑based compensation expense	9,270	7,013
Net amortization of premium (accretion of discount) on marketable securities	(3,780)	255
Changes in operating assets and liabilities:
Collaboration receivable	(5,025)	0
Prepaid expenses and other current assets	(3,894)	(12,020)
Right-of-use assets, operating leases	11,146	5,609
Other non-current assets	(11,754)	(82)
Accounts payable	(5,211)	694
Accrued expenses and other current liabilities	1,857	6,104
Operating lease liabilities	(12,703)	(5,437)
Deferred revenue	158,946	0
Net cash provided by (used in) operating activities	143,816	(66,482)
Cash flows from investing activities:
Purchases of property and equipment	(4,638)	(2,179)
Purchases of marketable securities	(318,686)	(221,977)
Maturities of marketable securities	165,886	56,714
Net cash used in investing activities	(157,438)	(167,442)
Cash flows from financing activities:
Proceeds from issuance of common stock in connection with the Vertex Agreement	19,407	0
Proceeds from exercise of stock options	754	121
Proceeds from issuance of common stock under the employee stock purchase plan	186	0
Net cash provided by financing activities	20,347	121
Net increase (decrease) in cash, cash equivalents, and restricted cash	6,725	(233,803)
Cash, cash equivalents, and restricted cash at beginning of period	49,107	291,064
Cash, cash equivalents, and restricted cash at end of period	55,832	57,261
Supplemental cash flow disclosures:
Purchases of property and equipment included in accounts payable and accrued expenses	299	32
Right-of-use assets obtained in exchange for operating lease liabilities	77,584	0
Right-of-use assets surrendered as part of lease modification	7,761	0
Recognition of right-of use asset upon adoption of ASC 842	0	32,991
Transfer of deposits for equipment from operating to investing cash flows	617	495
Vesting of options early exercised subject to repurchase	$ 72	$ 102