Reduced Intensity Conditioning (RIC) Allogeneic Stem Cell Transplantation (allo-SCT) in Patients with Multiple Myeloma (MM): Long Term Follow-up in a Single Centre Series

Background: RIC allo-SCT has been proposed as a strategy for retaining the graft versus myeloma effect of allo-SCT while decreasing transplant related mortality (TRM). Here, we retrospectively studied a series of 15 patients (pts) with MM treated by RIC allo-SCT.

Patients and methods: Between April 2001 and December 2007, 15 pts with MM underwent RIC allo-SCT with an HLA-identical sibling donor. Initially, 8 pts had MM with Ig G, one IgA, 2 light chains, 3 non-secretory and one undetermined. Three pts were stage II and 12 stages III. At time of allo-SCT, 6 pts were in complete remission and 9 in refractory/progressive disease (2 received prior autologous transplants). Median age was 48 years (range, 38–60) and the sex-ratio (M/F) 1,5. Median time from diagnosis to RIC allo-SCT was 18 (range, 6–76) months. The conditioning regimen included Fludarabine 150mg/m² and Melphalan 140mg/m². GVHD prophylaxis consisted of association cyclosporine (cSA) and mycophenolate (MMF). All pts received G-CSF mobilised peripheral blood stem cells, with a median CD34+ cell count: 4,5.10⁶/kg (range, 1.92–13).

Results: Neutropenia occurred in all pts and the median duration of aplasia was 8 (range, 5–14) days. Only 3 pts (20 %) required red blood cells transfusions and 12 pts (80 %) needed platelets transfusions. Acute GVHD was observed in 6 cases (40 %) including 4 cases of grade II–IV. Eight pts (72 %) had chronic GVHD, of whom 5 with an extensive form. Three pts (20 %) had CMV reactivation at a median time 91 (range, 53–158) days after transplantation. Four pts (26 %) had late onset relapse at a median time of 826 (range, 248–1370) days. TRM was 33 % at one year after RIC allo-SCT. With a median follow-up of 50 (range 14–86) months, 5 pts (33 %) are still alive in complete remission with full donor chimerism. Ten pts (66 %) died (2 early severe infections, 3 acute GVHD, 3 after relapse, one myocardial infarction, and one public highway accident). Overall and progression-free survivals at 7 years are 37,5 % and 31,2 % respectively.

Conclusion: This study suggests that RIC allo-SCT is a potential therapy for relapsed MM. However, TRM and relapse remain a matter of concern, likely due to the inclusion of refractory and heavily pretreated pts with many comorbid conditions. Future protocols, should aim for better patient selection, focussing on those pts in first chemosensitive relapse.