Efficacy of Allogeneic Hematopoietic Stem Cell Transplantation with Cocktail Conditioning Regimen for the Treatment of Pediatric Patients with Chronic Active Epstein-Barr Virus: A Retrospective Observational Study.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was considered as an only therapeutic strategy for chronic active Epstein-Barr virus (CAEBV) infection with few exceptions, while efficacy of various allo-HSCT conditioning regimens for CAEBV has not been fully investigated yet. This study aimed to compare the effectiveness of cocktail conditioning regimen (CCR)-allo-HSCT with reduced-intensity conditioning regimen (RICR)-allo-HSCT for pediatric patients with CAEBV. Data of a total of 54 children with CAEBV from July 2015 to December 2020 were retrospectively analyzed. Among them, 32 patients received VP16, total body irradiation (TBI), busulfan, fludarabine, cyclophosphamide, and antithymocyte globulin (ATG) (CCR1 group), 10 patients received VP16, ara-C, TBI, busulfan, fludarabine, cyclophosphamide, and ATG (CCR2 group), and the remaining 12 patients received VP16, busulfan or melphalan, fludarabine, and ATG with or without ara-C (RICR group). The overall survival (OS), hematopoietic engraftment, the incidence of severe graft-versus-host disease, and other parameters were analyzed. After adjusting for potential confounders, CCR1 (hazard ratio [HR]: 0.023; 95% confidence interval [CI]: 0.001-0.448;  < 0.02) and CCR2 (HR: 0.028; 95% CI: 0.002-0.457;  < 0.02) were associated with a longer OS than RICR. The use of CCR could markedly improve the engraftment success rate and OS rate compared with RICR for pediatric patients with CAEBV.