High Dose Simvastatin Has No Beneficial Effect on Markers of Bone Turn-Over in Multiple Myeloma.

Background: Bone degradation in multiple myeloma (MM) is a result of increased bone degradation by osteoclasts that is not compensated for by bone forming osteoblasts. Ideally new drugs used for treatment of MM should target not only the myeloma cells but also the imbalance between bone resorption and bone formation. Statins have been shown to inhibit myeloma cell proliferation and induce apoptosis in vitro. Furthermore statins have been shown to stimulate osteoblasts and inhibit osteoclasts both in vitro and in animal models. Statins are normally used at doses around 20–80 mg/day, but in order to reach serum concentrations that can match the in vitro experiments MM patients were treated with 15 mg/kg/day of Simvastatin (HD-Sim) divided in two daily doses in this study. This high dose has previously been found to be safe for MM patients (Haematologica 2006, 91,542–545)

Patients and methods: Six patients with advanced MM have been included in this pilot study, 4 males and 2 females with an average age of 68 years and an average duration of disease of 43 months. The patients were treated with 2 cycles of HD-Sim for seven days followed by a break of 21 days in a 4-weeks cycle. Two of the patients were treated with bisphosphonates during the study, and 4 had previously been treated with bisphosphonates. Endpoints are change in concentrations of markers of osteoclast activity (TRAP) or bone resorption (CTX, NTX, ICTP) or markers of bone formation (Osteocalcin and PINP). Cholesterol, OPG and DDK-1 were also measured.

Results: Two patients completed the protocol with two cycles of HD-Sim at full dose, 2 patients were reduced to 7.5 mg/kg/day simvastatin in cycle 2 due to nausea and diarrhea and 2 patients left the protocol after 3 weeks (deaths not related to high dose simvastatin). All patients experienced gastrointestinal toxicity grade 1–2. Myalgia and other muscular symptoms grade 1–2 were reported by 5 patients but were not associated with an increase in creatin kinase. TRAP and NTX activity in serum increased for all 6 patients during the seven days of treatment with HD-Sim indicating that bone resorption may have been stimulated rather than inhibited. The other markers of bone resorption and the bone formation markers showed no change. All patients responded with a significantly reduced level of cholesterol in serum. None of the patients showed any reduction in free monoclonal light chains or monoclonal proteins in serum during treatment with HD-Sim and 2 of the 4 patients completing the protocol showed progression of diseases.

Conclusion: This pilot study of HD-Sim in advanced MM has been terminated due to lack of response and evidence from two markers of osteoclast activity (TRAP) and bone resorption (NTX) that HD-Sim may be harmful rather than beneficial in MM.