In vitro statins, inhibitors of the HMG-CoA-reductase, have been shown to overcome cell adhesion mediated drug resistance at very low concentrations. The purpose of the study is to investigate the in vivo efficacy of simvastatin as inhibitor of cell adhesion mediated drug resistance. Patients refractory to ongoing chemotherapy will receive concomitantly simvastatin and response will be monitored by paraprotein levels