Similar Relationship Between the Time Course of Bone Mineral Density Improvement and Vertebral Fracture Risk Reduction With Denosumab Treatment in Postmenopausal Osteoporosis and Prostate Cancer Patients on Androgen Deprivation Therapy

Denosumab has received approval in many countries and indications include treating women with postmenopausal osteoporosis (PMO) at increased or high risk for fracture and men at high risk for fracture receiving androgen deprivation therapy (ADT) for non-metastatic prostate cancer. Increases in total hip bone mineral density (BMD) with denosumab explained a large percentage of new vertebral fracture risk reduction in women with PMO; however, this effect has not been studied in men with prostate cancer receiving ADT. We compared the relationship between the time course of BMD changes and new vertebral fracture risk reduction with denosumab in women with PMO and men with prostate cancer. After adjusting for different baseline hazards, a significant and similar relationship between time course of total hip and lumbar spine BMD changes and new vertebral fracture risk was observed in both patient populations. Time course of total hip BMD changes with denosumab was the best predictor for changes in fracture risk and explained 88% of the new vertebral fracture risk reduction in women with PMO and 91% in men with prostate cancer. Therefore, total hip BMD is a useful surrogate to measure the clinical impact of denosumab on fracture risk reduction in both patient populations.