Prevention of Symptomatic Skeletal Events With Denosumab Administered Every 4 Weeks Versus Every 12 Weeks

Denosumab, a monoclonal antibody against RANK-Ligand has been shown superior to zoledronic acid in delaying time to a first on-study skeletal related event (SRE) in patients with solid tumors, with no effects on disease progression or survival. Many SREs were silent compression fractures found only because of scheduled imaging. The approved dose of denosumab is 120 mg s.c. every 4 weeks (q4w). Although generally well tolerated, there is a time-dependent increase in osteonecrosis of the jaw in up to 8% of patients. Cases of fatal hypocalcaemia were observed during post marketing surveillance. The optimal dose and schedule for denosumab is unknown. Denosumab is associated with considerable costs and may add toxicity; thus a study of de-escalation is warranted. The aim of the trial is to test the hypothesis that the benefit of Denosumab is maintained if administered 120 mg q12w as compared to 120 mg q4w. The primary endpoint of this open-label randomized phase III non-inferiority trial is time to first on-trial symptomatic skeletal event (SSE: i.e. clinically significant pathological fracture, radiation therapy to bone, surgery to bone or spinal cord compression). With a non-inferiority margin of 1.2 for the hazard ratio, a power 80% and a type I error 5%, the total sample size is 1380. Secondary endpoints are safety, time to subsequent on-trial SSE, quality of life, health economic outcomes, and change in bone turnover markers. This study is open for international collaboration.