66P Impact of MAF selection of patients for adjuvant bisphosphonate therapy and comparison with current clinical guidance

Bisphosphonates (BP) do not have regulatory approval for use as adjuvant therapy in early breast cancer due to the failure of pivotal trials such AZURE and NSABP B-34. However, an EBCTBG meta-analysis randomized data showed clear clinical benefit from BP postmenopausal (PM) women both ESMO ASCO guidelines recommend their this population. Retrospective analyses MAF biomarker B-34 demonstrated a significant on relapse death that was restricted 80% tumors were non-amplified (MAF(-)). We studied relative differences with without PM patients (pts) included all MAF(-)pts + trials. gene amplification determined by FISH analysis primary tumor using Test (Inbiomotion, Spain). For cohorts meta-analysis, rates untreated control pts (n=5668) 15.8% 8.7% respectively compared 13.4% 7.5% those (n=6099) treated. The reductions risk recurrence 15.2% 13.8% combined rate events 17.1% 8.9% (n= 1126) 13.0% 6.5% treated (n=1170) pts, translating into reduction 23.8% 26.3% favoring These results contrast markedly MAF(+)pts; Here 26.5% 30.4% while deaths occurred 13.7% 249) 15.9% 265) indicating are ineffective sub-group associated increase 14.6% relapses 16.1% deaths. measured identifies target population (MAF(-)) treatment BPs is independent menopausal status provides beneficial opportunity higher proportion than currently recommended guidelines.