Sustained increases in lumbar spine and hip BMD with denosumab therapy beyond 10 years

Denosumab therapy results in a sustained increase in BMD at the lumbar spine and hip and lower fracture rates during 10 years of treatment. However, data on efficacy and safety beyond 10 years are limited. We present the case of a female who demonstrated a large and continued rise in BMD after 10 years of denosumab therapy.

An 80-year-old woman was referred to our Bone Health Clinic for advice regarding osteoporosis diagnosed 1 year earlier on routine DXA: lumbar spine T-score of -4.2 (0.585 g/cm²) and total hip T-score of -4.0 (0.503 g/cm²). Her GP had commenced her on alendronate 70 mg once weekly. Given her low T-scores, treatment was switched to denosumab, which was continued over the next decade. In her 10th year of treatment, she fell and sustained a left hip fracture. Repeat DXA revealed a T-score of -2.7 (0.754g/cm2) in the lumbar spine and -3.0 (0.572g/cm2) in the total hip. Our orthogeriatric service advised her to continue denosumab until reassessment in 3 years. Follow-up DXA 3 years later revealed an 8.0% improvement in BMD at lumbar spine (0.814 g/cm², T-score -2.1), 6.6% at the total hip (0.610 g/cm², T-score -2.7) (see Table 1). Denosumab was continued with advice that lifelong therapy may be needed.

This case illustrates that denosumab therapy beyond 10 years can be associated with significant further increases over a subsequent 3 years in BMD at both the lumbar spine and total hip. This may allow some patients to achieve a desirable treatment target, though future studies on safety and efficacy are needed.