Prevention of Epstein-Barr Virus Reactivation With the ATG-based Haploidentical Protocol Combined With Rituximab in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

The goal of this clinical trial is to learn if adding rituximab to the ATG-based Protocol can prevent Epstein-Barr virus (EBV) from reactivating in children who have received an allogeneic haploidentical hematopoietic stem cell transplant. It will also learn about the safety of adding rituximab. The main questions it aims to answer are: Does giving rituximab twice during the conditioning regimen lower the number of children who have EBV reactivation after transplant? What medical problems or side effects do children experience when they receive rituximab in addition to the ATG-based Protocol? Researchers will compare the group that receives rituximab (two doses before transplant) with a control group that receives no rituximab, to see if the addition of rituximab effectively prevents EBV reactivation. Participants will: Receive either rituximab (two doses during the preconditioning phase) or no extra treatment (control group), depending on which group they are assigned to Have regular follow-up visits for blood tests to monitor their EBV-DNA levels Keep a record of any symptoms or health changes they notice between visits