Clofarabine Pre-conditioning Followed by Stem Cell Transplant for Non-remission AML

Approximately 30-40% of patients with acute myeloid leukemia (AML) experience induction failures. In these patients who do not achieve remission with two cycles of standard induction therapies, the probability of achieving remission with subsequent inductions is limited. Hematopoietic stem cell transplantation (HSCT) is the only curative option for these patients, but high relapse rate and transplant-related mortality often preclude them to proceed to transplant. Thus, AML not in remission at time of HSCT remains a huge unmet need in current HSCT practice, particularly if the patient does not have a Human Leukocyte Antigen (HLA)-matched donor identified by the time of two induction failures. Salvage chemotherapy with clofarabine appears to be another promising option in relapsed and refractory AML. Clofarabine is a second-generation purine nucleoside analog with substantial single-agent activity in adult patients with AML. It is an effective immunosuppressive agent and several trials have shown the feasibility of conditioning with clofarabine-based regimen. In the past, a conditioning regimen of clofarabine with busulfan (4 doses) has been successfully used prior to allogeneic stem cell transplantation for non-remission AML with day +30 complete remission rates were 90-100%. However, these patients were transplanted with HLA matched donors. This study will examine those patients undergoing transplantation from haploidentical related donor or matched and mismatched unrelated donors. Achieving a long-term remission is clearly the goal of AML treatment. The investigators would like to propose a protocol for non-remission AML and expand the patient population to older than 55 years of age as well as those who relapsed after initial allogeneic transplant to improve enrolling patients in the near future. The investigators have many patients achieving remission but for those without remission, clofarabine preconditioning may be a reliable protocol to bring these patients into the early complete remission.