ERBB2 and breast cancer: High gene copy number of MET and HGF was found to significantly associate with an increased risk of trastuzumab-based therapy failure (e.g., shorter time to disease progression) in HER2-positive metastatic BC. MET and HGF FISH-positive status was highly correlated (p < 0.001) and combination of both biomarkers did not increase predictive value of either considered separately [123].