Reported in this research investigation is the anti-neoplastic cytotoxicity of gemcitabine-(C4-amide)-[anti-EGFR] and gemcitabine-(C4-amide)-[anti-HER2/neu] against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) applied simultaneously as a dual selectively “targeted” chemotherapeutic regimen. This evidence concerns the gene ERBB2 and breast adenocarcinoma.