The dual simultaneous combination of gemcitabine-(C4-amide)-[anti-EGFR] with gemcitabine-(C4-amide)-[anti-HER2/neu] evaluated as a gemcitabine-standardized 50/50 molar equivalent formulation in addition to gemcitabine-(C4-amide)-[anti-EGFR] and gemcitabine-(C4-amide)-[anti-HER2/neu] all produced progressive increases in anti-neoplastic cytotoxicity against chemotherapeutic resistant mammary adenocarcinoma (SKBr-3) as a function of increases in gemcitabine-equivalent concentration at and between 10−10 M and 10−6 M (Figure 8). The gene discussed is ERBB2; the disease is breast adenocarcinoma.