Summary/Proposal: Reduced Intensity Hematopoietic Cell Transplantation for High-Risk Relapsed Pediatric Hematologic Malignancies and Patients Ineligible for Standard Transplantation We propose a phase II trial of reduced intensity conditioning with Bu/Flu/ATG in pediatric patients with hematologic malignancies at high risk for transplant related mortality with standard transplantation. Patients qualify based on organ system dysfunction, active but stable infection, history of previous transplant, or late stage disease. We plan to enroll 45 patients through the Pediatric Blood and Marrow transplant Consortium (PBMTC) and anticipate that the outcome of the trial will pave the way for phase II or III disease specific protocols addressing efficacy of the approach compared to standard transplant approaches in better risk patients.
Hypothesis High risk pediatric hematologic malignancy patients ineligible for standard myeloablative HCT undergoing reduced intensity conditioning (RIC) HCT can achieve a sustained engraftment rate \> 90% with a 100day TRM \< 30% using either bone marrow or PBSC from related or unrelated donors. High risk pediatric patients undergoing RIC-HCT using related or unrelated cord blood can achieve a sustained engraftment rate \>80% and a 100d TRM \<30%.
Rationale for Reduced Intensity Approaches in High Risk Patients There are a number patient-specific risk factors associated with increased transplant related mortality. They can be broadly placed into three categories: pretransplant organ system dysfunction, active infections at the time of transplant, and degree of pretransplant therapy (previous transplants, third or subsequent remission, etc.).
The primary objective of this study is to determine the likelihood of achieving sustained donor engraftment using reduced intensity conditioning (fludarabine/busulfan/ATG) followed by hematopoietic cell transplantation (HCT) with either cord blood, bone marrow or peripheral blood stem cells (PBMTC) in pediatric patients with hematopoietic malignancies who are at high risk of transplant related mortality (TRM) with myeloablative HCT. Patients qualify based on organ system dysfunction, active but stable infection, history of previous transplant or late stage disease. We plan to enroll 45 patients through the Pediatric Blood and Marrow Transplant Consortium (PBMTC) and anticipate that the outcome of the trial will pave the way for phase II or III disease specific protocols addressing efficacy of the approach compared to standard transplant approaches in better risk patients.
Study procedures Patients receive their conditioning regimen consisting of fludarabine, busulfan, and ATG and then receive their stem cell transplant. Patients receive immunosuppression consisting of cyclosporine and mycophenolate mofetil. Patients with persistent or progressive disease may receive donor lymphocyte infusion off protocol.
