Evaluation Of The Role Of P95 Her2 Isoform In Trastuzumab Efficacy In Metastatic Breast Cancer

trastuzumab efficacy in regards to progression-free survival and overall survival. Results: HER2 was centrally negative in 54 cases. P95 expression was significantly higher in HER2-positive tumors. High p95 was associated with gain of HER2 copy number variations (CNVs), high pHER2Tyr877, Ki67 and HER2 mRNA. P95 as a continuous variable was positively correlated with mRNA expression of HER2 and negatively correlated with HER4 and IGF1. HER2-negative p95-high patients had a marginally higher risk for death (HR=2.15, p=0.055). Conclusion: p95 was associated with higher HER2 CNVs and mRNA expression, pHER2Tyr877 expression and high Ki67, indicating a more aggressive phenotype.