Low incidence of Epstein-Barr virus-associated posttransplantation lymphoproliferative disorders in 272 unrelated-donor umbilical cord blood transplant recipients

Umbilical cord blood (UCB) is being increasingly used for transplantation, but the ability of neonatal T cells to regulate Epstein-Barr virus (EBV)-associated lymphoproliferation is unknown. Because UCB transplantation (UCBT) is associated with a relatively low infused dose of donor T cells, frequent donor-recipient HLA disparity, and use of antithymocyte globulin during conditioning, we hypothesized that the risk of EBV-associated post-transplantation lymphoproliferative disorders (EVB-PTLD) after UCBT may be increased. To investigate the incidence of EBV-PTLD after UCBT, we analyzed 272 unrelated-donor UCBTs performed from August 1993 to December 1999 at Duke University Medical Center and the University of Minnesota. Five cases of EBV-PTLD were identified, with a cumulative incidence of 2% (95% confidence interval, 0.3%-3.7%) at 2 years. EBV-PTLD affected UCB recipients aged 1 to 49 years (median, 8 years), with 4 patients undergoing transplantation for leukemia and 1 for immunodeficiency. Patients received UCB grafts that were HLA matched (n = 1) or mismatched at 1 (n = 1) or 2 (n = 3) HLA loci. Diagnoses occured at 4 to 14 months (median, 6 months) after UCBT, with 4 of 5 patients having preceding grade II to IV acute graft-versus-host disease and 1 being diagnosed at autopsy. Treatment of 4 patients consisted of withdrawal of immunosuppressive treatment and administration of rituximab, with 2 of 4 patients responding. Thus, the incidence of EBV-PTLD after unrelated-donor UCBT appears similar to that observed after transplantation using unrelated bone marrow (BM) and compares favorably with unrelated-donor T-cell-depleted BM transplantation. Because adoptive immunotherapy with donor lymphocytes is not an available option for recipients of unrelated-donor UCBT, new therapeutic strategies are needed, and rituximab appears promising.