Radioimmunotherapy with [188Re]-labelled anti-CD66 antibody in the conditioning for allogeneic stem cell transplantation for high-risk acute myeloid leukemia.

Between July 2000 and June 2003 a total of 21 patients with high-risk acute myeloid leukemia (AML; n = 14), AML after myelodysplastic syndrome (MDS; n = 6) or advanced MDS (n = 1) were treated with an 188-Re labelled anti-CD66 antibody in the conditioning regimen for allogeneic stem cell transplantation. Radioimmunotherapy (RIT) was followed by standard full-dose conditioning with busulfan and high-dose cyclophosphamide in 11 patients and reduced intensity conditioning regimen in 10 patients. All patients received an unmanipulated allogeneic graft from alternative donors (n = 15) or a HLA-identical familiy donor (n = 6). With a median follow up of 42 months (23-60) disease free survival for all patients was 43%. Nine patients are still alive and in ongoing complete hematological remission. The treatment related mortality was 28.6% (n = 6) and an equal number of patients died of relapsing disease within 30-385 days after transplantation. Late organ toxicity, monitored for more than 1 year, was mild and not clinically relevant. The combination of RIT with chemotherapeutic conditioning seems to be a therapy with an acceptable risk of treatment related morbidity and mortality as well as occurrence of severe acute GvHD.