Transfusion utilization during gene therapy for sickle cell disease: A single institution experience

Gene therapy (GT) is a transformative therapy for sickle cell disease (SCD) that requires transfusion support to suppress hemoglobin S (HbS) for hematopoietic progenitor cell (HPC) mobilization and autologous hematopoietic cell transplantation (HCT). Given the prevalence of red blood cell (RBC) alloimmunization in patients with SCD and recommendations to provide prophylactic minor antigen matching, knowledge of transfusion utilization and duration during the GT process is necessary for transfusion management.

We performed a retrospective review of transfusion utilization of all patients with SCD who received GT at our center through 2024. Transfusions were recorded for three time periods: (1) ≤120 days before first HPC collection, (2) time from first collection to HPC infusion, (3) HPC infusion to transfusion independence.

Nine patients received GT, 4 (44%) with RBC alloimmunization. One patient became alloimmunized (ant-Jk^a) during pre-HPC transfusion management. Four patients had 1 mobilization cycle, 5 patients had 2 cycles, with a median of 3 collection days (1-5). Median RBC transfusion utilization was 38 units (range 27-55): 15 units (9-27) for Period 1, 20 units (10-30) for Period 2, 6 units (4-9) for Period 3. Median platelet utilization was 13 units (7-31) in Period 3.

The transfusion support of patients with SCD during GT has unique considerations due to RBC transfusion requirements for HPC mobilization cycles. This single institution report will help support transfusion planning and decision making about the feasibility of transfusion support for patients with extensive RBC alloimmunization.