Equivalent incidences of paediatric graft-versus-host disease regardless of donor-recipient matching in the era of modern prophylaxis agents.

Recipients of haploidentical and unrelated haematopoietic cell transplants (HCTs) historically had a higher risk for graft-versus-host disease (GvHD). However, with improved GvHD prophylaxis, recent data suggest adult patients undergoing transplantation from unrelated or mismatched donors now experience the rates of GvHD similar to those receiving matched related donor grafts. This finding is not yet explored in paediatric patients. The objectives of this study were to: (1) compare acute and chronic GvHD incidence, mortality and GvHD-free relapse-free survival (GRFS) among matched related donor (MRD), matched unrelated donor (MUD) and haploidentical paediatric HCT recipients in the era of enhanced GvHD prophylaxis for high-risk patients, (2) identify independent risk factors for GvHD and (3) evaluate the efficacy of various GvHD prophylactic regimens in our cohort. We conducted a retrospective, single-centre medical record abstraction among patients aged 0-25 years who underwent allogeneic HCT for any indication. The results demonstrated that 5-year cumulative incidence rates of any GvHD, all-cause mortality and GRFS are similar across the haploidentical, MRD and MUD groups. Tacrolimus-containing doublet/triplet regimens were associated with decreased GvHD, as compared to ciclosporin. Adding alemtuzumab also decreased risk for GvHD, without increasing relapse rates. Prospective studies with larger cohorts are warranted to further optimize outcomes for paediatric allogeneic HCT patients.