Sequence matters: Total body irradiation (TBI)-based myeloablative conditioning with post-transplant cyclophosphamide may reduce the early nonrelapse mortality compared with pretransplant cyclophosphamide plus TBI

Abstract

Objectives: High-dose total body irradiation (TBI) is considered a cornerstone of myeloablative conditioning for allogeneic stem cell transplantation (allo-SCT). We retrospectively compared the main outcomes of an HLA matched or 1-allele mismatched related or unrelated allo-SCT in adult patients affected by acute leukemia (AL) or myelodysplastic syndromes (MDS). Methods: Fifty-nine patients received cyclophosphamide (Cy)-TBI (13.5 Gy) and graft-versus-host disease (GVHD) prophylaxis with a calcineurin-inhibitor plus methrotrexate (CyTBI group) and 28 patients received fludarabine-TBI (8.8–13.5 Gy) and GVHD prophylaxis with PTCy and tacrolimus (FluTBI-PTCy group). Results: Median follow-up for survivors was 82 and 22 months. The 12-month probability of overall survival and progression-free survival were similar (p =.18, p =.7). The incidence of Grades 2–4 and 3–4 acute GVHD, and the incidence of moderate-to-severe chronic GVHD were higher in the CyTBI group (p =.02, p