Long Term Toxicity and Follow-up of Waldenstrom's Macroglobulinemia Patients after Salvage Treatment with Fludarabine Cyclophosphamide Rituximab or Bendamustine and Rituximab

Introduction Fludarabine, cyclophosphamide and rituximab (FCR) and bendmaustine rituximab (BR) combinations have both been evaluated as salvage regimens in Waldenstrom's Macroglobulinemia. FCR exerts good quality of responses but there are some concerns regarding its use mainly for tardive myelosuppression and long term toxicity. BR showed to be effective with an excellent short term toxic profile but in literature there are no data on long term follow-up and toxicity. The aim of this study was to evaluate long term outcome and long term toxicity of patients treated with FCR and BR. Patients and Methods We analyzed 87 relapsed and refractory Waldenstrom's Macroglobuklinemia patients enrolled in two retrospective Italian multicenter studies in which FCR or BR were administered as salvage regimens. Patients treated with both bendamustine and fludarabine were excluded from the study. For each treatment group we compared: clinical and disease characteristics, Progression free survival (PFS) defined as progression or death for any cause from the beginning of salvage treatment; Event free survival (EFS) defined as progression or development of major infection, solid tumor, secondary MDS/AML, DLBCL, or death due to any cause. Results Of the 87 patients, 37 had received FCR and 50 BR. The two groups of patients did not differ in sex, median age, median number of prior treatments, previous therapy with alkylating agents, disease status, median IgM level, presence of adenopathies and/or splenomegaly at CT performed before salvage treatment. The significant differences between the two groups were: higher number of patients >70 years in the BR group (P=0.01) and lower number of patients previously treated with monoclonal antibody in the FCR population (P Conclusions FCR and BR as salvage regimens led to similar outcome in terms of PFS and EFS. Considering that FCR in respect to BR exerts long lasting responses the main issue remains its long term toxicity profile. The future challenge will be to assess the long term effect of the new targeted agents. Disclosures Ferrero: Mundipharma: Other: Speakers Honoraria; Celgene: Other: Speakers Honoraria.