Receiver operating characteristic curve analysis of the HER2DX pCR score among all patients (A), hormone receptor (HR)–negative patients (B), and HR-positive patients (C). D, Expression of the 4 HER2DX gene expression signatures (immune, proliferation, luminal, and ERBB2 [formerly HER2] amplicon) across the HER2DX pCR score high, medium, and low groups. AUC indicates area under the curve; IGG immunoglobulin G; IHC, immunohistochemistry.