This is a national, multicenter, phase IIa, single arm (not controlled), open label clinical trial of Simvastatin 80mg p.o. /day in a population of patients with progressive SMM. Patients will be treated with Simvastatin 40 mg and if no side effect will be seen the dose will be escalated to 80 mg for up to 18 months. All further treatment decisions after completion of the study are at the discretion of the investigator.Approximately 15 patients will be enrolled.