[A multicenter study of allogeneic hematopoietic stem cell transplantation for stage 4/M neuroblastoma].

<b>Objective:</b> To evaluate the effectiveness and safety of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with stage 4/M neuroblastoma (NB). <b>Methods:</b> This study was a prospective, single-arm, multicenter clinical trial conducted by Sun Yat-sen Memorial Hospital, Children's Hospital of Nanjing Medical University, Children's Hospital, Zhejiang University School of Medicine, the First Affiliated Hospital of Guangxi Medical University, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. From March, 2019 to August, 2023, 25 children with confirmed with stage 4/M NB and received allo-HSCT were enrolled. The patients received either unrelated cord blood transplantation (UCBT) or peripheral blood stem cell transplantation (PBSCT). Conditioning regimens for UCBT was fludarabine+busulfan+cyclophosphamide+topotecan, and for PBSCT was fludarabine+busulfan+melphalan+thiotepa+antithymocyte globulin, respectively. Until the last follow-up date of September, 2023, the overall survival (OS) rate and event free survival (EFS) rate were analyzed to evaluate efficacy. The engraftment rate and transplant-related complications were statistically assessed to evaluate safety. Survival analysis was performed using the Kaplan-Meier method. <b>Results:</b> Of the 25 patients, there were 15 males and 10 females. The age at transplantation was 5.7 (3.8, 7.3) years. The engraft rate was 100%, with recovery time of neutrophil as 15.7 (12.5, 17.0) d, and the recovery time of platelets as 33.5 (18.0, 48.0) d. Seventeen of the 25 children (68%) developed acute graft versus host disease (aGVHD), occurred at 18.0 (13.0, 22.5) d after transplantation, including 13 of grade Ⅲ-Ⅳ cases. The main sites of aGVHD were skin and intestinal tract. After treatment, 13 cases improved, 4 patients developed chronic graft-versus-host disease (cGVHD). After allo-HSCT, 14 children received maintenance therapy. Twenty of the 25 patients survived, the 2-year cumulative OS rate was (80±9)%, and 2-year EFS rate was (56±11)%. Nine cases (36%) relapsed, the time from allo-HSCT to disease relapse was 10.9 (5.5, 16.0) months. Five cases (20%) died. The hematopoietic stem cell transplantation associated mortality rate was 4% (1/25).The 2-year OS rate of patients who had partial remission prior to allo-HSCT was significant lower than those who had complete remission prior to allo-HSCT ((33±25)% <i>vs.</i> 100%, <i>P</i>=0.037). <b>Conclusion:</b> allo-HSCT is an effective treatment for patients with stage 4/M NB.