Allogeneic Hematopoietic Stem Cell Transplantation for 4/M Neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor of embryonal origin in children. According to the International Neuroblastoma Risk Group (INRG) staging criteria and the International Neuroblastoma Staging System (INSS) ，NB preoperative staging is divided into L1, L2, M and Ms stages, the postoperative staging is divided into 1 to 4 stages and 4s stage. Among them, 4/M stage is of the highest degree of malignancy and the worst prognosis. Despite the aggressive combination therapy, the 5-year survival rate (OS) is still less than 15%, and the 2-year relapse rate is 80%. Currently, no effective treatment is accessible for refractory/relapsed stage 4/M NB after completing conventional therapy. In hematopoietic stem cell transplantation (HSCT) , conditioning regimen with high-dose radiotherapy and chemotherapy is implemented to eradicate tumor cells and abnormal clonal cells in the patient, block the pathogenesis, and restore the patient's hematopoietic and immune systems by transplanting normal hematopoietic stem cells. According to the source of hematopoietic stem cells, HSCT can be divided into two types: autologous hematopoietic stem cell transplantation (auto-HSCT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). It has been confirmed that benefiting from the graft versus tumor(GVT) effect, allo-HSCT can clear residual lesions in refractory/relapsed NB patients post-auto-HSCT，and prolong the survival time of patients. Our center has explored the conditioning regimen, treatment of residual tumor lesions before transplantation, and strategies to reduce transplantation-related death (TRM) and enhance the GVT effect. However, the sample size is small, and multicenter and larger sample size research are needed. This study will further observe the clinical efficacy and safety of allo-HSCT in the treatment of 4/M stage NB, and provide a new treatment method and option for 4/M stage NB.