- Adjuvant denosumab has already been shown by ABCSG-18 to reduce hip fracture in postmenopausal hormone receptor (HR)-positive women being treated with aromatase inhibitors (AIs) for early breast cancer (eBCa). The rationale for using denosumab was that AIs are known to increase risk for osteoporosis and fractures.
- In this follow-up to ABCSG-18, adjuvant denosumab improves DFS by 18%.
Why this matters
- If replicated, adjuvant denosumab may become the standard of care to prevent osteoporotic fractures and improve DFS in postmenopausal women with HR+ eBCa being treated with AIs.
- Phase 3 trial of 3425 postmenopausal Austrian and Swedish patients who were stratified by previous AI use and total lumbar spine bone mineral density score at baseline, among other characteristics, were randomly assigned to subcutaneous denosumab (60 mg) or placebo every 6 months during AI therapy.
- The primary outcome (already reported) was time to first clinical fracture after randomization.
- The secondary outcome (reported here) was DFS.
- Funding: Amgen.
- Median follow-up was 73 months.
- The denosumab group had an 18% improvement in DFS vs placebo (HR, 0.82; 95% CI, 0.69-0.98).
- No independently adjudicated cases of osteonecrosis of the jaw or confirmed atypical femoral fracture were seen.
- Both groups experienced similar numbers of adverse events.
- No exploration of mechanism of action.