Clinical Outcome of UCBT for Children with CAEBV: A Retrospective Analysis of a Single Center.

Background: Chronic active Epstein-Barr virus (CAEBV) infection is a severe, life-threatening condition characterized by persistent Epstein-Barr virus (EBV) infection and the clonal expansion of infected T or NK cells, leading to systemic inflammation, organ damage, and complications such as hemophagocytic lymphohistiocytosis and lymphoma. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only effective treatment for eradicating EBV-infected cells; however, donor availability is limited. Umbilical cord blood stem cell transplantation (UCBT) is a promising alternative owing to its rapid availability and lower complication risk. However, there are fewer existing reports on UCBT in pediatric patients with CAEBV.

Objective: This study aimed to assess the feasibility and clinical efficacy of UCBT as a potential treatment for pediatric patients with CAEBV.

Study Design: We investigated children with CAEBV who did not have matched donors and underwent UCBT in the First Affiliated Hospital of Zhengzhou University and Zhengzhou People's Hospital, China, between 2016 and 2022. We retrospectively analyzed the clinical characteristics, pretreatment regimens, transplantation-related complications, and clinical outcomes of this group of cases to explore the efficacy of UCBT in CAEBV treatment in children.

Results: Eight patients, including four males and four females, with a diagnosis age of 4 (1-8) years and a transplantation age of 4 (2-8) years, were enrolled in this study. The mean time from diagnosis to transplantation was 5 (2-14) months. The mean follow-up period for surviving patients was 49.75 ± 29.66 months, with a maximum follow-up of 101.0 months. All eight patients exhibited successful engraftment. Acute GVHD was observed in six patients, while chronic GVHD was observed in only one patient, with the case being relatively mild. 2 patients developed CMV reactivation. EBV reactivation and post-transplant lymphoproliferative disease (PTLD) were not observed. Case 4 experienced relapse 10 months post-UCBT and achieved survival following a subsequent haplo-identical HSCT from her father. Case 8 succumbed to thrombotic microangiopathy(TMA) on post-transplant day 50. By the end of the follow-up, the 3-year overall survival rate(OS) was estimated to be 87.5% (95% confidence interval [CI]: 0.529-0.994). The 3-year EFS rate was estimated to be 75% (95% CI: 0.409-0.956). The estimated 3-year GRFS rate was also 75.0% (95% CI: 0.409-0.956).

Conclusions: UCBT emerges as a safe and effective treatment for CAEBV in children, serving as a viable alternative for patients without matched donors or emergency transplantation.