ERBB2 and breast cancer: HER3 overexpression predicts resistance to trastuzumab, though HER3 expression has not been shown as a predictive factor in combination treatment of trastuzumab and pertuzumab in HER2+ breast cancers.[95] HER2-positive cells also acquire resistance to trastuzumab through increased ADAM10-mediated HRG release.[96] HER3 overexpression also correlates with resistance to lapatinib.