A Prospective Study on Modulation of Immunosuppression for Epstein-Barr Virus Reactivation in Pediatric Patients Who Underwent Unrelated Hematopoietic Stem-Cell Transplantation

Background. Posttransplant lymphoproliferative disease caused by Epstein-Barr virus (EBV-PTLD) is a severe complication after allogeneic hematopoietic stem-cell transplantation (HSCT). We evaluated whether the modulation of immunosuppression (IS) guided by quantitative polymerase chain reaction for EBV (EBV-PCR) was effective as a first-line therapeutic approach for EBV reactivation. Methods. Eighty-nine pediatric patients who received an HSCT from an unrelated donor were prospectively assessed by quantitative EBV-PCR. The EBV-PCR threshold to modulate IS was set to more than 300 genomic copies (gc)/10(5) peripheral blood mononuclear cells. Results. EBV-PCR positivity was observed in 56 (63%) of 89 patients at a median time of 44 days after HSCT. The variables associated with EBV-PCR positivity were bone marrow stem cells (P=0.047) and a lower total dose of nuclear cells reinfused (P=0.03). Thirty-one patients (35%) had more than or equal to 300 gc. IS was withdrawn or reduced in 18 (58%) and 13 (42%) of the 31 patients, respectively. EBV viral load (EBV-VL) less than 300 gc was achieved in 30 of these 31 patients at a median of 25 days. Only 1 (1%) of the 89 patients progressed to EBV-PTLD. The patients with EBV-VL more than 300 gc had a lower incidence of acute graft versus host disease III-IV than patients with EBV-VL less than 300 gc: 13% vs. 36%, P=0.02. No differences in terms of chronic graft versus host disease, overall survival, event-free survival and transplant-related mortality were observed between the two groups. Conclusions. We conclude that PCR-guided modulation of IS may play a role in early intervention for EBV-PTLD and a prospective, randomized study is needed.