Role of Osteocytes in Myeloma Bone Disease

Progress in the treatment of myeloma and myeloma bone disease has substantially increased overall survival, but relapse is inevitable and better treatment is needed. The bone microenvironment is tremendously complex, so that targeting single interactions between tumor and bone is unlikely to be effective. Treatments need to block centrally important, multifunctional pathways. The investigators data point to a central role of the osteocyte to induce heparanase, a multifunctional mediator of myeloma bone disease. Increased heparanase due to FGF23 may make systemic inhibitors of heparanase less effective in bone than elsewhere. FGF23 neutralizing antibodies have been developed for non-cancer conditions of FGF23 excess, such as chronic kidney disease (Shimada \& Fukamoto, 2012), and could be used in MM alone or in combination with heparanase inhibitors. Complete neutralization of FGF23 has adverse effects, but neutralization of FGF23 excess may be practical, or in the future, suppression of excess FGF23 biosynthesis by osteocytes. The investigators hope to determine serum FGF23 and heparanase, Dkk1 and plasma klotho levels in patients with newly diagnosed and relapsed myeloma compared to healthy controls with this exploratory study.