RESPONSE: Re: Effect of Epidermal Growth Factor Receptor Inhibitor on Development of Estrogen Receptor-Negative Mammary Tumors

Extract

In their correspondence, Campiglio et al. comment that epidermal growth factor receptor (EGFR) blockade induced by the tyrosine kinase inhibitor ZD1839 (i.e., gefitinib) may offer new opportunities to fight breast cancer. We certainly agree and appreciate their comments pertaining to our recently reported results (1). They also raised very reasonable questions about the mechanism by which this agent suppresses mammary tumor development. We would like to respond to these important questions.

First, the authors asked whether the data from our recent experiments showing that ZD1839 suppresses estrogen receptor (ER)-negative mammary tumorigenesis in transgenic mice can be extrapolated to humans, clearly a critical question. We admit that the answer to this question awaits human clinical cancer prevention trials using EGFR inhibitors. However, until the results from these human studies are available, in our opinion the results in the MMTV-erbB2 mice offer the most relevant preclinical data supporting development of signal transduction inhibitors for the prevention of ER-negative human breast cancer.