The following table illustrates information about segment revenue, significant segment expenses and segment operating loss for the periods presented (in thousands):

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

(2) Research and development expense for the three and nine months ended September 30, 2026 excludes $8.1 million and $23.8 million of stock-based compensation expense, respectively, and $2.1 million and $6.5 million of depreciation expense, respectively. Research and development expense for the three and nine months ended September 30, 2025 excludes $7.6 million and $25.1 million of stock-based compensation expense, respectively, and $2.3 million and $7.0 million of depreciation expense, respectively. Research and development expense for the periods presented also excludes costs related to the Sirius Agreement, described further below.

(3) Acquired in-process research and development expense for the three and nine months ended September 30, 2026 was $11.7 million and $14.1 million, respectively, and primarily consisted of a development milestone under the Sirius Agreement that was recognized in the third quarter of 2026. Acquired in-process research and development expenses for the nine months ended September 30, 2025 were attributable to the costs incurred upon entering the Sirius Agreement during the second quarter of 2025, as described in Note 6.

(4) General and administrative expense for the three and nine months ended September 30, 2026 excludes $9.8 million and $27.8 million of stock-based compensation expense, respectively, and $2.1 million and $6.4 million of depreciation expense, respectively. General and administrative expense for the three and nine months ended September 30, 2025 excludes $9.0 million and $29.3 million of stock-based compensation expense, respectively, and $2.2 million and $6.7 million of depreciation expense, respectively.

(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.

(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 nine months ended September 30, 2025 to reflect the updated significant expense categories.

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