Abatacept for acute graft versus host disease prophylaxis in children with sickle cell disease patients undergoing HLA identical sibling hematopoietic stem cell transplantation.

Abatacept reduces the risk of acute graft versus host disease (GVHD) in matched unrelated donor hematopoietic stem cell transplant (HSCT) for Sickle Cell Disease (SCD). We conducted a retrospective review of patients who underwent matched sibling donor (MSD) HSCT for SCD with and without adding abatacept to standard acute GVHD prophylaxis. Twenty-one patients, median age 7 years (range 2.0-14.8) received MSD HSCT with addition of 4 doses of abatacept to standard calcineurin inhibitor based acute GVHD prophylaxis while six patients, median age 9.8 years (range 1.9-14.4) underwent MSD HSCT with standard prophylaxis. One patient (4.5%) in the abatacept group developed grade II acute skin GVHD, while 3 patients (50%) in standard group developed grade II-III acute skin and gut GVHD (p = 0.022). Grade III-IV GVHD was 0% in abatacept group compared to 33% in standard group (p = 0.043). Disease-free survival was 83% in standard group at a median follow up of 11 years (IQR:9.5-13.25 years), and 100% in the abatacept group at a median follow up of 5 years (IQR:3-8 years). Our data show that addition of abatacept to calcineurin inhibitor based acute GVHD prophylaxis reduces the risk of severe acute GVHD in patients with SCD undergoing MSD HSCT without impacting disease-free survival.