Condensed Consolidated and Combined Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (85,711)	$ (87,196)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Change in fair value of contingent consideration	48	369
Depreciation and amortization	3,530	3,676
Stock-based compensation expense	9,739	17,109
Other non-cash items	1,227	69
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(7,768)	2,262
Operating lease right-of-use assets	4,710	3,652
Accounts payable	6,228	4,535
Accrued expenses and other liabilities	280	(1,248)
Operating lease liabilities	(2,860)	(5,639)
Deferred revenue	0	(820)
Collaboration research advancement	(3,487)	(1,519)
Net cash used in operating activities	(74,064)	(64,750)
Cash flows from investing activities:
Purchases of property, plant and equipment	(3,585)	(6,351)
Purchases of marketable securities	(22,450)	0
Proceeds from maturities of marketable securities	70,784	0
Net cash provided by (used in) investing activities	44,749	(6,351)
Cash flows from financing activities:
Transfers from bluebird bio	0	71,101
Proceeds from issuance of common stock in private placement	170,000	0
Proceeds from exercise of stock options and ESPP contributions	99	0
Net cash provided by financing activities	170,099	71,101
Increase (decrease) in cash, cash equivalents and restricted cash	140,784	0
Cash, cash equivalents and restricted cash at beginning of period	163,266	0
Cash, cash equivalents and restricted cash at end of period	304,050	0
Reconciliation of cash, cash equivalents, and restricted cash
Cash and cash equivalents	270,893	0
Restricted cash included in restricted cash and other non-current assets	33,157	0
Total cash, cash equivalents, and restricted cash	304,050	0
Supplemental cash flow disclosures:
Purchases of property, plant and equipment included in accounts payable and accrued expenses	2,925	1,954
Private placement issuance costs included in accounts payable and accrued expenses	$ 4,343	$ 0