Tandem autologous/reduced-intensity conditioning allogeneic stem-cell transplantation versus autologous transplantation in myeloma: long-term follow-up

Purpose Results of allogeneic stem-cell transplantation (allo) in myeloma are controversial. In this trial autologous stem-cell transplantation (auto) followed by reduced-intensity conditioning matched sibling donor allo (auto-allo) was compared with auto only in previously untreated multiple myeloma. Patients and Methods In all, 357 patients with myeloma up to age 69 years were enrolled from 2001 to 2005. Patients with an HLA-identical sibling donor were allocated to the auto-allo arm (n = 108) and patients without a matched sibling donor were allocated to the auto arm (n = 249). Single (n = 145) or tandem (n = 104) auto was optional. Conditioning for the auto arm was melphalan 200 mg/m2; conditioning for the allo arm was total-body irradiation 2 Gy plus fludarabine 30 mg/m2/d for 3 days. Median follow-up time was 61 months. Primary end point was progression-free survival. Results Progression-free survival at 60 months was significantly better with auto-allo than with allo alone (35% v 18%; P = .001), as was the risk of death and of relapse in the long term (P = .047 and P = .003, respectively). Overall survival at 60 months was 65% versus 58%, and relapse incidence was 49% versus 78%. Complete remission rates were 51% and 41%, respectively (P = .020). Nonrelapse mortality at 24 months was 12% after auto-allo compared with 3% in the auto group (P < .001). The incidence of grade 2 to 4 acute graft-versus-host disease (GvHD) was 20%, and the incidence of limited and extensive chronic GvHD was 31% and 23%. Conclusion In patients with previously untreated multiple myeloma, long-term outcome with respect to progression-free survival, overall survival, and relapse rate is superior after auto-allo compared with auto only. Nonrelapse mortality is at a reasonable level in both groups.