RETROSPECTIVE COMPARISON OF CD34-SELECTED ALLOGENEIC PERIPHERAL BLOOD STEM CELL TRANSPLANTATION FOLLOWED BY CD8-DEPLETED DONOR LYMPHOCYTE INFUSIONS WITH UNMANIPULATED BONE MARROW TRANSPLANTATION Running tittle: CD34-selected PBSCT plus CD8-depleted DLI versus unmanipulated BMT

We have previously reported the feasibility of allogeneic CD34-selected PBSC transplantation followed by pre-emptive CD8-depleted DLI (study group). In this report, we retrospectively compare the clinical outcome of the 24 patients included in this study with an historical group of 35 patients receiving unmanipulated marrow (BMT group). Patients in the study group had significantly faster neutrophil and platelet recovery and were discharged earlier than BMT patients. The actuarial 150-day (after DLI) probability of developing grade IIIV acute GVHD was 28% for the study group versus 62% for the BMT group (p=0.002). The actuarial 2-yr probability of developing chronic GVHD was similar (37% versus 36% (NS)) but chronic GVHD was significantly delayed in the study group (p=0.003). The actuarial 2-yr probability of relapse was 30% in the study group versus 33% in the BMT group (NS). The actuarial 2-yr probability of survival was 45% in the study group versus 43% in the BMT group (NS). We conclude that allogeneic transplantation of CD34-selected PBSC followed by preemptive CD8-depleted DLI is feasible with rapid engraftment and minimizes the risk of severe GVHD. Large prospective trials are required to confirm these results.