TNFSF11 and osteoporosis: However, in the recent years several novel anti-osteoporosis drugs have been developed, such as monoclonal antibodies against RANKL (Denosumab-Prolia®), or against sclerostin (a novel protein secreted by osteocytes which is a negative regulator of bone formation) (Blosozumab and Romosozumab, not allowed by FDA yet) (24).