Syngeneic transplantation in multiple myeloma - a case-matched comparison with autologous and allogeneic transplantation

Twenty-five patients with multiple myeloma received bone marrow grafts (n = 24) or peripheral blood stem cells (n = 1) from twin donors. The outcome w as compared in a case-matched analysis to 125 patients who underwent autolo gous transplantation, and 125 who underwent allogeneic transplantation. Sev enteen patients (68%) receiving twin transplants entered complete remission , which was not significantly different from that of autologous (48%) or al logeneic (58%) transplants. The median overall and progression-free surviva l for the twins was 73 and 72 months, respectively. The overall survival te nded to be better (73 vs 44 months) and the progression-free survival was s ignificantly better (72 vs 25 months) than with autologous transplantation and both were significantly better than with allogeneic transplantation. Th ree of 17 patients who entered complete remission following transplantation had relapsed at follow-up. This relapse rate was significantly lower than following autologous transplantation and similar to the relapse rate with a llogeneic transplantation. Only two twins died of transplant-related toxici ty. Six further patients died of progressive or relapsing disease. Syngenei c transplantation in multiple myeloma appears to be the treatment of choice if a twin donor is available. A lower relapse risk than in autotransplanta tion may be due to reinfusion of malignant cells in some patients treated w ith this modality or to the presence of a graft-versus-myeloma effect in so me syngeneic transplants.