EGFR and cancer: Expression of EGFR does not correlate with efficacy of the EGFR antibody cetuximab11 and the use of the antibody is limited by toxicity.12 In recent clinical studies of EGFR-expressing breast13 and colorectal14 cancer patients, response rates to EGFR-targeted therapies were low and varied between cancer types, with the majority of patients eventually developing resistance to these reagents.