Acute Myeloid Leukemia T Cell Depletion to Improve Transplants in Adults With Acute Myeloid Leukemia (BMT CTN 0303)

BACKGROUND: Allogeneic hematopoietic cell transplantation is an accepted therapy for AML. Transplants of unmodified HLA-matched related bone marrow or peripheral blood stem cells following conditioning with total body irradiation (TBI) and cyclophosphamide or VP-16 or busulfan and cyclophosphamide have led to sustained DFS rates of 45-60% for adults transplanted in first complete remission (CR1) and 40-53% for patients transplanted in second complete remission (CR2). In several single center and multicenter cooperative group prospective trials comparing HLA-matched allogeneic transplants to chemotherapy in the treatment of AML in CR1, DFS rates for the transplant arm were almost invariably superior; however, these advantages were statistically significant in only a minority of the cooperative group studies conducted. In each study, the risk of relapse was significantly lower for patients receiving allogeneic transplants. However, this advantage was counterbalanced by transplant-related mortality, principally reflecting infections complicating GVHD and its treatment. DESIGN NARRATIVE: Despite increased risks of infection, development of effective T cell depletion (TCD) techniques for prevention of GVHD and tolerable modifications of regimens for pre-transplant cytoreduction that secure consistent engraftment offer the potential for significant decreases in transplant-related mortality. Furthermore, the use of TCD transplants in the treatment of patients with AML is not associated with substantial increases in the incidence of relapse. Several single center trials indicate highly encouraging long-term results, particularly for patients with AML in CR1 or CR2. Although the number of cases in each single center series is limited, the consistency of the results suggests that the use of an effective technique for TCD together with an adequate cytoreductive regimen might yield transplant results superior to those achieved with unmodified grafts.