Haploidentical hematopoietic stem cell transplantation for pediatric patients with chronic active Epstein-Barr virus infection: a retrospective analysis of a single center.

Background: This study aimed to evaluate the feasibility and clinical effect of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) for the treatment of pediatric patients with chronic active Epstein-Barr virus infection (CAEBV).

Methods: Children with CAEBV who did not have matched donors and underwent haplo-HSCT in Beijing Children's Hospital, Capital Medical University, from October 2016 to June 2020 were analyzed retrospectively. Data relating to the clinical manifestations, engraftment, and prognosis of the children were extracted from medical records.

Results: Twenty-five patients, including 16 males and 9 females, with an onset age of 5.0 ± 2.6 years and a transplantation age of 6.9 ± 2.9 years, were enrolled in this study. The mean time from diagnosis to transplantation was 3.8 (2.0-40.2) months. The mean observation time was 19.0 ± 12.0 months. Three patients received the reduced intensity conditioning regimen, and the remaining patients all received the modified myeloablative conditioning regimen. By the end of the follow-up, 23 patients were characterized by disease-free survival (DFS), 22 were characterized by event-free survival (EFS), and two died. One of the patients died of thrombotic microangiopathy (TMA), and another died of graft versus host disease (GVHD); this patient discontinued the treatment for economic reasons. The 3-year overall survival (OS) rate was estimated to be 92.0% ± 5.4%, and the 3-year EFS rate was estimated to be 87.4% ± 6.8%. All active patients survived after HSCT event-free. Acute GVHD degrees 1-3 were observed in ten patients (40.0%), and degree IV was observed in six (24.0%), who were all cured except for one patient. Chronic GVHD was observed in nine (36.0%), and most of these cases were mild. The incidence of TMA and veno-occlusive disease (VOD) was 28.0% and 4.0%.

Conclusions: Haploidentical hematopoietic stem cell transplantation is safe and effective in the treatment of pediatric CAEBV and can be used as an alternative therapy without matched donors or emergency transplantation. Patients with active disease before HSCT also benefited from haplo-HSCT. Haplo-HSCT requires careful monitoring for complications, such as GVHD and TMA. Early detection of TMA and timely treatment can reduce mortality and can improve the survival rate.