Use of Post-Transplant Cyclophosphamide in Matched Related and Unrelated Donor Hematopoietic Stem Cell Transplant for...

Introduction of Post-Transplant Cyclophosphamide (PTCy) based immunosuppression in Haploidentical Hematopoietic Stem Cell Transplants (HSCT) has shown to reduce the incidence of Graft vs. Host Disease (GVHD). However, data on its use in HLA matched settings is lacking. We describe our experience using PTCY in pediatric patients undergoing matched donor HSCT. We retrospectively analysed data of 16 patients who underwent HLA-matched HSCT using PTCy from March 2022-July 2024 at our institute. Sixteen patients of median age-6 years (Range:1-17 years) were analysed. Indications of transplant were Thalassemia in 10, severe aplastic anemia in 5 and Congenital dyserythropoietic anemia in 1. Conditioning regimes used were Rabbit ATG-Thio-Flu-Cy-2 Gy TBI in 8 and Rabbit ATG-Thio-Treo-Flu-2 Gy TBI in 3 which was preceded by two cycles of pre-transplant immunosuppression (PTIS); Rabbit ATG-Flu-Cy-4 Gy TBI in 5 patients of aplastic anemia. PTCy, Mycophenolate mofetil and cyclosporine were used as GVHD prophylaxis. One patient had primary and another had CMV induced secondary graft failure. Three patients had grade I-II acute GVHD at median 32days post HSCT (Range: 28-140days). None of the patients had chronic GVHD. CMV reactivation occurred in 8 patients at a median + 21 days (Range: 14-35 days). Median follow up duration post HSCT was 473days (Range:85-808 days). 1 year- Event-free and 1 year-overall survival rates were 81.25% and 93.7% respectively. PTCy-based approach appears to be promising in matched related and unrelated donor transplants for benign hematological disorders.