Allogeneic stem cell transplantation reduces disease progression compared to autologous transplantation in patients with multiple myeloma

This study compares the probability of disease progression, progression-fre e survival, and overall survival between patients undergoing an allogeneic or autologous transplant for multiple myeloma using an identical preparativ e regimen. Patients received a preparative regimen of TBI, busulfan, and cy clophosphamide followed by an allogeneic or autologous transplant. In the a llogeneic group (n = 21), six patients received bone marrow and 15 received G-CSF mobilized PBSC; all autologous patients (n = 35) received PBSC mobil ized with cyclophosphamide and G-CSF. Allogeneic donors were HLA-identical (n = 20) or one-antigen mismatched (n = 1) siblings. Graft-versus-host dise ase (GVHD) prophylaxis consisted of tacrolimus (n = 10), tacrolimus/methotr exate (n = 6), cyclosporine/methotrexate (n = 4), or cyclosporine (n = 1). The groups were evenly matched for gender, pretransplant therapy, disease s tatus at time of transplant, myeloma subtype, and time from diagnosis to tr ansplant. The median age was significantly lower in the allogeneic group (4 8 vs 55 years, P < 0.01). In the allogeneic group the probabilities of deve loping acute GVHD grade II-IV and chronic GVHD were 55% and 82%, respective ly. The Kaplan-Meier probability of disease progression was significantly l ower in the allogeneic group (11% vs 64%, P < 0.001) compared to the autolo gous group. Although progression-free (60% vs 30%, P = 0.19) and overall su rvival at 2 years (60% vs 42%, P = 0.39) favored the allogeneic group, this did not reach statistical significance. Within the allogeneic transplant g roup, patients age 50 years or under had a 3-year overall survival signific antly higher when compared to older patients (79% vs 29%, P = 0.03). Using identical preparative regimens, allogeneic transplantation reduced disease progression compared to autologous transplantation for myeloma. This sugges ts that allogeneic transplantation induces a graft-versus-myeloma (GVM) eff ect.