v3.26.1
Segment Information - Schedule of Reportable Segment Profit and Loss, Including Significant Expense Categories, Attributable to the Company's Reportable Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Revenues [Abstract]            
Total revenue $ 10,181   $ 892   $ 11,639 $ 1,757
Operating Expenses [Abstract]            
Research and development 67,152   69,894   135,726 142,378
Acquired in-process research and development 2,473   96,253   2,473 96,253
General and administrative expense 17,553   18,916   34,736 38,212
Collaboration expense, net 40,272   45,153   86,221 102,662
Stock-based compensation expense         33,640 37,819
Depreciation expense 4,300   4,600   8,600 9,300
Segment net loss         (214,085) (344,545)
Net loss (91,154) $ (122,931) (208,549) $ (135,996) (214,085) (344,545)
Sirius [Member]            
Operating Expenses [Abstract]            
Acquired in-process research and development     96,300     96,300
Collaboration Revenue [Member]            
Revenues [Abstract]            
Total revenue 10,000   0   11,000 0
Grant Revenue [Member]            
Revenues [Abstract]            
Total revenue 181   892   639 1,757
Operating Segments [Member]            
Operating Expenses [Abstract]            
Research and development [1],[2] 53,708   59,232   110,737 119,565
Acquired in-process research and development [1],[3] 2,473   96,253   2,473 96,253
General and administrative expense [1],[4] 5,957   6,840   12,553 13,357
Stock-based compensation expense [1] 17,316   17,607   33,640 37,819
Depreciation expense [1] 4,280   4,631   8,582 9,349
Other segment items [1],[5] (26,115)   (20,775)   (33,432) (33,203)
Segment net loss (91,154)   (208,549)   (214,085) (344,545)
Adjustments or reconciling items 0   0   0 0
Net loss (91,154)   (208,549)   (214,085) (344,545)
Operating Segments [Member] | Vertex [Member]            
Operating Expenses [Abstract]            
Collaboration expense, net [1],[6] 40,272   45,153   86,221 102,662
Operating Segments [Member] | Sirius [Member]            
Operating Expenses [Abstract]            
Collaboration expense, net [1],[7] 3,444   500   4,950 500
Operating Segments [Member] | Collaboration Revenue [Member]            
Revenues [Abstract]            
Total revenue 10,000   0   11,000 0
Operating Segments [Member] | Grant Revenue [Member]            
Revenues [Abstract]            
Total revenue $ 181   $ 892   $ 639 $ 1,757
[1]

(1) The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM.
[2]

(2) Research and development expense for the three and six months ended June 30, 2026 excludes $7.8 million and $15.7 million of stock-based compensation expense, respectively, and $2.2 million and $4.4 million of depreciation expense, respectively. Research and development expense for the three and six months ended June 30, 2025 excludes

$7.8 million and $17.5 million of stock-based compensation expense, respectively, and $2.4 million and $4.8 million of depreciation expense, respectively.
[3]

(3) Acquired in-process research and development expense for the three and six months ended June 30, 2026 was not material. The $96.3 million acquired in-process research and development expense for the three and six months ended June 30, 2025 is attributable to the costs incurred upon entering the Sirius Agreement, as described in Note 6 of the notes to our unaudited condensed consolidated financial statements included in this Quarterly Report on Form 10-Q.
[4]

(4) General and administrative expense for the three and six months ended June 30, 2026 excludes $9.5 million and $17.9 million of stock-based compensation expense, respectively, and $2.1 million and $4.2 million of depreciation expense, respectively. General and administrative expense for the three and six months ended June 30, 2025 excludes $9.8 million and $20.3 million of stock-based compensation expense, respectively, and $2.3 million and $4.6 million of depreciation expense, respectively.
[5]

(7) Other segment items include interest income (expense), net, the change in fair value of corporate equity securities and income tax expense.
[6]

(5) Collaboration costs specific to the Vertex Hemoglobinopathy Agreements (as defined in Note 6) accounted for under ASC 808 are presented within “collaboration expense, net” in the condensed consolidated statements of operations and comprehensive loss.
[7]

(6) In the second quarter of 2025, the Company entered into the Sirius Agreement (as defined in Note 6). Collaboration costs, net of reimbursements, related to the Sirius Collaboration Products under the Sirius Agreement are presented within “research and development expense” in the condensed consolidated statements of operations and comprehensive loss. In the first quarter of 2026, the significant expense categories reviewed by the CODM were updated to include collaboration costs, net of reimbursements, associated with the Sirius Collaboration Products. As a result, the Company recast segment amounts for the three and six months ended June 30, 2025 to reflect the updated significant expense categories.