The covalent immunochemotherapeutics, gemcitabine-(C4-amide)-[anti-EGFR] and epirubicin-(C3-amide)-[anti-HER2/neu] both exerted selectively “targeted” anti-neoplastic cytotoxicity against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) populations (Figures. This evidence concerns the gene ERBB2 and breast adenocarcinoma.