Two high-dose chemotherapy regimens (melphalan alone versus the combination of melphalan and bendamustine) used for conditioning treatment before autologous stem cell transplantation will be compared in a 1:1 randomization in myeloma patients. The experimental arm is the bendamustine and melphalan (BenMel) combined regimen. The melphalan alone (Mel) regimen is the control (standard) treatment. Despite remarkable progress using novel agents both for induction before ASCT as well for maintenance after ASCT, definite cure in myeloma patients remains exceptional due to residual disease escaping intensive treatment. The aim of the study is to show an improvement of the rate of complete Remission 60 days after ASCT in myeloma patients from 50% with melphalan alone to 65% with the combination of bendamustine and melphalan.