Studies have shown that the Epidermal Growth Factor Receptor (EGFr) is overexpressed in 30-50% of breast carcinomas and that overexpression correlates with poor patient prognosis. Recent studies suggest that EGFr positivity may be predictive of poor patient response to endocrine therapy. Studies have also shown that certain tumor cell lines release the extracellular domain (ECD) of EGFr into cell culture fluids and therefore the potential exists for the detection of EGFr in sera of cancer patients. To test this hypothesis, we have developed an ELISA specific for the ECD of EGFr that can be used to screen patient sera for positive reactivity. In this Phase I application we propose to use the EGFr ELISA to evaluate sera from individuals with primary or metastatic breast cancer, individuals that significantly elevated levels of EGFr above controls will be evaluated biochemically for the presence of full length or truncated versions of EGFr. Corresponding tumor tissue will be evaluated by immunohistochemistry to determine the EGFr status of the tumor. Serum reactivity and EGFr expression in the tumor will then be compared.
