135P Five-year survival analysis of phase II ZoNAnTax trial: Evaluation of zoledronic-acid addition to a neoadjuvant trastuzumab, anthracycline and docetaxel-containing regiment

Pathological complete response (pCR) is a surrogate biomarker of survival in Human Epidermal Growth Factor Receptor 2-positive (HER2+) breast cancer (BC) and more likely to occur hormonal receptor (HR) negative (-). In the early efficacy safety analysis ZoNAnTax trial, 4 cycles doxorubicin/cyclophosphamide with ZOL, followed by docetaxel trastuzumab ZOL prior surgery induced similar pCR rates HR positive (+) 40% HR- 44%, were well tolerated. The translational demonstrated mechanistic behind clinical results, including crosstalk between WNT, HER2 estrogen pathways mevalonate pathway modulation being relevant treatment HR+/HER2+BC. Here we present 5-years (5y) disease-free (DFS) overall (OS) for entire study sample according status stratified HR. Kaplan-Meier Survival curves estimated, Log-rank statistical test was performed evaluate hypothesis differences groups at 5% level significance. From 71 HER2+ BC patients stage IIA-IIIB, 58 eligible analysis. Overall DFS rate 79.3%, achieving 83.3% versus (vs) non-pCR 76.5% (p=0.57), HR+ 81% vs 75% (p=0.58). 71.4% 71.8% (p=0.72) 88.2% 76% (p=0.32). OS 86.2%, 95.8% 79.4% (p=0.08), 85.7% 87.5% (p=0.91). 100% 77.8% (p=0.23) 94.1% 80% (p=0.20). Taken together efficacy, long-term benefit regimen demonstrating as high reported pivotal studies that contained Pertuzumab same setting, suggests adding repositioning drug NT should be considered.