Treatment Challenges When Stopping Denosumab.

Introduction Denosumab is commonly used to treat osteoporosis. However, discontinuation results in rebound bone loss and increased vertebral fracture risk. We report a clinical case series, illustrating the dilemma in deciding the best treatment should denosumab be stopped. Cases In eight patients aged 56-89 years, zolendronic acid after stopping denosumab resulted in BTM rises and BMD decline.  In a 68-year-old, two years of oral bisphosphonate after three years of denosumab resulted in elevated bone turnover markers (BTM) and decline in bone mineral density (BMD), necessitating a switch to zoledronic acid.  In a 79-year-old, two annual doses of zolendronic acid after three years of denosumab failed to suppress high BTM, with BMD dropping and denosumab being restarted.  In a 60-year-old, on stopping denosumab after 10 years of oral bisphosphonate, BMD remained stable despite no further therapy. Conclusion Drug holidays are not an option with denosumab, with a risk of bone loss even on transitioning to bisphosphonates. Risk is greater with longer duration of treatment6 and may be mitigated by prior bisphosphonate use. Standard dose zoledronic acid does not prevent bone loss in a significant proportion of patients. BTM may help in monitoring treatment and need for further bisphosphonates.