The first clinical trial evaluated the efficacy of recombinant Fc-OPG, used systemically as a drug for the treatment of osteoporosis in postmenopausal women (Bekker et al., 2001) and another study evaluated a different formulation of OPG, known as AMGN-0007, in patients with lytic bone lesions associated with multiple myeloma or breast carcinoma (Body et al., 2003). Here, TNFRSF11B is linked to breast carcinoma.