Factors influencing extramedullary relapse after allogeneic transplantation for multiple myeloma

Patients undergoing allogeneic stem cell transplantation (allo-SCT) with reduced intensity conditioning (RIC) for multiple myeloma (MM) experience a high frequency of extra-medullary relapses (EMR) (20–37%). This study aims at determining factors predictive for EMR after allo-SCT, prognosis of EMR and efficacy of salvage therapies. We retrospectively analyzed a continuous cohort of 79 patients with MM who received allo-SCT in one single center (Montpellier University Hospital, France) between 2000 and 2010. The median age at transplantation was 59 years (range 35–68). The median overall survival after allo-SCT was 2.6 years (0.1–12.8). Baseline characteristics of patients, previous treatments, immunological status before allo-SCT, allo-SCT modalities and post-allo immune recovery are indicated in Table 1. Allo-SCT was performed in first line of treatment (13% including 6% tandem auto allo-SCT), second line (47% including 6% of patients with primary refractory disease and 41% of patients with chemo-sensitive post auto-SCT relapse, relapse having occurred at a median of 2.1 years post auto-SCT) or third or more lines of treatment (40%). RICs used in most cases (97%) were FBS (fludarabine, intra-venous busulfan +/− thymoglobulin) (n= 44), FluTBI (fludarabine, total body irradiation) (n= 17) or Flu Cy TBI (Fludarabine, cyclophosphamide,