TNFSF11 and giant cell tumor: The fully human monoclonal anti-RANKL antibody denosumab, which inhibits the binding of RANKL to RANK, has been approved as a treatment for osteoporosis and the prevention of skeletal-related events in patients with bone metastasis and giant cell tumours of the bone.21 However, since the high cost of therapeutic antibody drugs has an increasing impact on the health-care burden, less expensive alternative approaches such as low-molecular weight inhibitors must be developed.