A humanized monoclonal antibody (MoAb) against human epidermal growth factor receptor (EGFR) with antineoplastic activity. Depatuxizumab targets the EGFR deletion variant, de2-7 EGFR as well as wild-type EGFR expressed in cells overexpressing the receptor, thereby preventing the activation and subsequent dimerization of the receptor; the decrease in receptor activation and dimerization result in an inhibition in signal transduction and anti-proliferative effects. This MoAb targets cells expressing aberrant EGFR, hence making it an ideal candidate for generation of radioisotope or toxin conjugates.