Reduced intensity conditioning T depleted allogeneic transplants in AML: Are there any factors predicting favourable outcomes?

Reduced intensity conditioning (RIC) regimens permit the extension of a potentially curative graft-versus-leukemia effect to older patients with acute myeloid leukemia (AML) whose outlook with conventional chemotherapy would be poor. T cell depletion using alemtuzumab reduces the risk of severe graft-versus-host disease (GVHD) after RIC allografts but may compromise anti-leukemic activity. We have therefore analyzed which factors predict long term survival in 65 patients with AML transplanted using an alemtuzumab based RIC regimen. The 100 day transplant related mortality for the whole cohort of patients was 10%. 30% of patients developed Grade II-IV acute GVHD and 21% chronic GVHD. The 3 year overall survival was 47%. Survival was significantly influenced by status at transplant (p = 0.002), presentation cytogenetics (p = 0.03) and the presence of a molecular mismatch at Class 1 or II HLA alleles in patients transplanted using an unrelated donor (p = 0.001) but not by age. Alemtuzumab based RIC regimens have the capacity to deliver sustained remissions in older patients with AML with a modest risk of GVHD but patients with active disease at the time of transplant or adverse cytogenetics require novel transplant strategies. Alternative stem cell sources should be considered in patients lacking a sibling or molecularly matched unrelated donor