Graft versus host disease in unmanipulated haploidentical marrow transplantation with a modified post-transplant cyclophosphamide (PT-CY) regimen: an update on 425 patients

This is an update on acute and chronic graft-versus-host disease (GvHD) in 425 patients with hematologic malignancies, undergoing an unmanipulated haploidentical (HAPLO) graft from related donors, with a modified post-transplant cyclophosphamide (PT-CY) regimen. All patients received a myeloablative conditioning regimen, either based on thiotepa busulfan fludarabine (TBF), or on full-dose total body irradiation (TBI). The cumulative incidence of acute GvHD-grade II-IV was 29%, and the CI of GvHD-grade III-IV was 4%. We found older donors and older patients to have higher rates of grade II-IV acute GvHD; female donors, diagnosis, disease phase, year of transplant, and the conditioning regimen had no predictive effect on acute GvHD. There was no impact of grade II GvHD, but a significant impact of grade III-IV acute GvHD, on overall survival. The CI of moderate-severe chronic GvHD was 18%: the major predictor was a previous acute GvHD, followed by combined donor and recipients age. In conclusion, PT-CY given on days+3 + 5 results in a relatively low, but not insignificant risk of acute and chronic GvHD, in patients grafted from the related HAPLO donors. The use of young donors appears to reduce this risk.