As the primary goal is to prove the hypothesis that simvastatin can overcome drug resistance in vivo only patients not responding to chemotherapy will be included. Chemotherapy is defined as bortezomib and bendamustin, as both are effective and approved drugs in the therapy of relapsed myeloma. Further inclusion criteria are age over 18 years, proven MM (serum protein below 11g/dl, life expectancy > 3 months) and treatment indication with measurable paraprotein. In the case of no change (paraprotein increase less than 25% and paraprotein decline less than 50%) after two cycles of bortezomib (one cycle: 1.3 mg/m2 d1,4,8,11) or bendamustin (one cycle: 100 mg/m2 d1+2) the patients will receive two further cycles with concomitant simvastatin treatment (80 mg daily starting two days before chemotherapy and stopping two days after chemotherapy). Exclusion criteria are severe organ failure and risk factors for rhabdomyolysis (untreated hypothyroidism, active liver disease, terminal renal insufficiency, acute infectious disease, myopathy, heriditary myopathy in the family history, alcohol abuse, comedication with itraconazole, ketoconazole, erythromycin, clarithromycin, HIV protease inhibitors, nefazodone, cyclosporine, fibrates, niacin, amiodarone, verapamil).