A total of 40 patients will be entered in this study. Half of the patients will receive standard intravenous treatment with aminobsiphosphonates, the other half will be additionally be treated with a statin. Patients already receiving statin treatment will continue this treatment, other patients will be asked whether they are willing to be treated with a statin for a maximum of 5 weeks. Consenting patients will be randomized to receive i.v. aminobisphosponates plus or minus simvastatin 40 mg once daily. Simvastatin will be started one week prior to the first administration of aminobisphosphonates and continued for a maximum of 5 weeks. In each patient 10 ml peripheral blood will be drawn (t=0, t=24 hr, t=1 week, t=3-4 weeks (prior to the 2nd aminobisphosphonate administration). In addition, patients will be requested to measure their temperature thrice daily during the 2 days following the first aminobisphosponate administration. This, because a relation between the occurrence of a febrile response upon aminobisphosponate administration and an activation and expansion of Vy9Vd2-T cells has been suggested. Peripheral blood mononuclear cells will be isolated from the drawn peripheral blood. Using intra- and extracellular flowcytometry Vy9Vd2-T cells will be characterized phenotypically (APC markers: CD1d, CD40, CD80, CD83, CD86, HLA-DR; activation/memory markers: CD25, CD27, CD45RA, CD45RO, CCR7) and functionally (IFN-γ, TNF-α, granzyme B). In addition, the frequency of CD3+, CD4+, CD8+ T cells, NK cells, B cells, iNKT cells, CD4+CD25+ regulatory T cells, and circulating dendritic cells will be assessed.