Tandem autologous non-myeloablative allogeneic transplantation in patients with multiple myeloma relapsing after a first high dose therapy.

We retrospectively studied a series of 23 patients (median age 50 years, range 29-59 years) with multiple myeloma (MM), treated in first relapse by a sequential autologous-allogeneic tandem approach. Tandem transplantation (TT) consisted in high dose melphalan (HDT) and auto-SCT followed by an (allo-SCT) preceded by two gray TBI non-myeloablative conditioning. All patients received a first HDT as frontline treatment. At day 100 post allo-SCT, complete donor chimerism was detected in 22 patients (95%). Acute GVHD was observed in 19 patients (15 grade I-II (65%) and 4 grade III-IV (17%)). Ten patients (43%) developed an extensive chronic GVHD. The non-relapse mortality at 1 year was 17%. After TT, the overall response rate was 91% (17% partial response, 35% very good partial remission and 39% complete remission). At 2 years, OS was 61%. Median event-free survival and OS were 36.8 and 60 months, respectively. Based on the propensity score matching method, a significant survival advantage could be seen in patients treated with TT as compared with non-allografted patients. Thus, allo-SCT, in TT approach, provides a high response rate with low toxicity and may improve survival of patients with relapsing MM.