Intensification of the Conditioning Regimen for Patients with high-risk AML and MDS: 3 year Experience of using an188 Re — Labelled anti — CD 66 Monoclonal Antibody

We have intensified the conditioning regimen prior to stem cell transplantation in 42 patients with high-risk AML and MDS by treating patients with a 188 Re — labeled anti — CD 66 monoclonal antibody. Dosimetry was performed prior to therapy and a favourable dosimetry was observed in all cases. Radioimmunotherapy with the labeled antibody provided a mean of 15.3 Gy of additional radiation to the marrow, the kidney was the normal organ receiving the highest dose of supplemental radiation (mean 7.3 Gy): Radioimmunotherapy was followed by standard full-dose conditioning with total body irradiation (12 Gy) or busulfan and high — dose cyclophosphamide ± thiotepa. Patients subsequently received a T cell depleted allogeneic graft from a HLA — identical family donor (n = 16) or an alternative donor (n = 22). In 4 patients without an allogeneic donor an unmanipulated autologous graft was used. Infusion — related toxicity due to the labeled antibody was minimal and no increase in treatment — related mortality due to the radioimmunoconjugate was observed. Day +30 and day +100 mortalities were 2% and 5% respectively and after a median follow-up of 22 months treatment-related mortality was 24%. Late renal toxicity was observed in 14% of patients. The relapse rate of 19 patients transplanted in 1.CR or 2.CR was 16%, in 23 patients not in remission at the time of transplant we observed a 36% relapse rate.