Allogeneic Stem Cell Transplantation for Relapsed and Refractory Multiple Myeloma –a Single Institute Analysis of 10 Cases

Novel agents and autologous stem cell transplantation (ASCT) have dramatically prolonged overall survival (OS) of patients with multiple myeloma (MM). However, almost all patients relapse within several years after ASCT and some patients are refractory to standard treatment strategy. Allogeneic stem cell transplantation (allo-SCT) is potentially curative treatment option because of its tumor free graft and possibly graft-versus-myeloma effect, but high incidence of treatment related mortality (TRM) has been reported.

We report consecutive 10 patients with relapsed and refractory MM undergoing allo-SCT in Japanese Red Cross Medical Center between 2009 and 2014. Median age at transplantation was 50.5 (31-60). Number of previous ASCT was one in 5 patients and two in the others. Conditioning regimen consisted of fludarabine (Flu; 125mg/m2), melphalan (Mel; 140mg/m2), and total body irradiation (TBI; 0Gy:1, 2Gy:1, 4Gy: 1, 8Gy:7). Tacrolimus or cyclosporine with or without short term MTX was used as GVHD prophylaxis. Three out of ten patients received matched related peripheral blood stem cells and the others received unrelated stem cells (unrelated bone marrow: 5, cord blood: 2). Two years progression free survival (PFS) and OS were 39.4% and 57.9%, respectively. Interestingly, among patients transplanted from unrelated donors, two years PFS and OS were 41.7% and 80%, respectively. In this analysis, three patients died and causes of death were TRM in one patient with infection and disease progression in two patients. In earlier reports, myeloablative regimens were associated with high early mortality rate, because of acute graft versus host disease (aGVHD) and infection. In our report, 8 patients developed grade 2-4 aGVHD (grade 2: 5, grade 3: 3, grade4: 0), but none of them died. Although number of patients is small, allo-SCT with Flu+Mel+TBI is tolerable and effective treatment option for relapsed and refractory MM even with unrelated donors.