Outcome of reduced-intensity allogeneic hematopoietic stem cell transplantation (RISCT) using antilymphocyte antibodies in patients with high-risk acute myeloid leukemia (AML).

Hemopoietic stem cell transplantation (SCT) with fully ablative conditioning is associated with an age-related increase in treatment-related mortality. It is therefore particularly unsuited to older individuals, who are most at risk of developing acute myeloid leukemia (AML). Reduced-intensity SCT (RISCT) may be of value in this group. We report 17 consecutive patients with high-risk AML whose median age was 58 years and who received stem cells from HLA-matched siblings (n=5), or alternative donors (n=12). We used lymphodepleting antibodies as a part of the reduced-intensity conditioning regimen to limit the risk of graft rejection and graft-versus-host disease (GVHD). All patients engrafted. One patient developed severe fatal GVHD, and two patients died of infection. At a median follow-up of 861 days (372-1957 days), seven patients are alive in remission, which includes two patients treated in relapse and five patients who lacked an MHC identical sibling donor. Both progression-free survival and overall survival are 40% (95% CI, 17-64%). Hence, RISCT using lymphodepleting antibodies may be of value for older patients with AML, even in those with active or high-risk disease, and even if they lack an MHC-identical sibling donor.