ERBB2 and cancer: Lastly, as previously eluded to, the anti-neoplastic cytotoxicity of the dual simultaneous combination of the covalent gemcitabine immunochemotherapeutics, gemcitabine-(C4-amide)-[anti-EGFR] and gemcitabine-(C4-amide)-[anti-HER2/neu] would likely have been greater if their efficacy had been delineated in an in-vivo model for cancer such as human neoplastic xenographs in animal hosts.