Targeted immune depletion prior to reduced-intensity allogeneic stem cell transplantation results in rapid and complete donor chimerism with low treatment-related mortality

6540 Background: Significant variation in host immune status may influence outcomes after reduced-intensity (RI) allogeneic stem cell transplantation (alloSCT). We have investigated a strategy of targeted immune depletion (TID) with conventional chemotherapy to deplete host T cells and achieve a minimal disease state prior to RI alloSCT. The aim of TID is to rapidly establish complete donor chimerism after RI alloSCT in order to potentiate a graft-versus-tumor (GVT) effect. In a prospective phase II trial (NIH 03-C-0077), we evaluated the effect of TID on donor chimerism, acute graft-versus-host disease (GVHD), and clinical outcome. Methods: Thirty-one patients (pts) with relapsed and refractory hematologic malignancies (NHL = 16; HL = 4; CLL/PLL = 4; MDS/AML = 3; other = 4) were enrolled. Median age was 57 years (range: 31–71). All pts received EPOCH-F (etoposide, prednisone, vincristine, cyclophosphamide, adriamycin, fludarabine) ± rituximab (R) as TID to deplete host CD4+ cells <100/μL. All pts then re...