EGF-R and Her2/neu overexpressing tumors: independent collectives for treatment of breast cancer by specific monoclonal antibody-therapy.

PURPOSE: In our recent studies, we demonstrated that breast cancer treatment by anti-EGF-R antibody resulted in a significant therapeutic effect in vivo. Furthermore, we were able to elucidate histopathologic parameters with an impact on therapy success. The aim of this study was the evaluation of EGF-R and Her2/neu protein expression on a large series of primary breast cancer, to elucidate if anti-EGF-R antibody therapy is a new therapeutic option for patients who are Her2/neu negative and where, therefore, anti-Her2/neu antibody treatment is not applicable. METHODS: We analyzed EGF-R and Her2/neu protein expression of 149 consecutive primary breast cancer specimens by fully quantitative enzyme-linked immunosorbent assay. For evaluation of stochastic independence, we used chi(2)-test as goodness-of-fit test. RESULTS: We found EGF-R and Her2/neu expression as stochastically independent in primary breast cancer. CONCLUSIONS: Anti-EGF-R antibody treatment is a potential therapeutic option for patients with Her2/neu negative breast cancer.

Anti-epidermal growth factor receptor-antibody therapy for treatment of breast cancer.

Recent studies demonstrated that tumors overexpressing the epidermal growth factor receptor (EGF-R, erbB-1) are associated with poor clinical outcome. This led to the development of a variety of monoclonal antibodies targeting the extracellular domain of this receptor tyrosine kinase. The aim of our study was the evaluation of anti-EGF-R antibody EMD 55900 therapy for treatment of breast cancer. On the basis of 299 tumor specimens derived from breast cancer patients, we investigated EGF-R expression and generated a collective of primary xenotransplants in athymic nude mice. The animals received therapy in 2 treatment schedules to investigate the therapeutic response in early stages of tumor formation as well as on well established tumors. Using 6 different tumors with EGF-R expression levels between 10-300 fmol/mg total protein, we found a therapeutic effect when the EGF-R expression of the tumors was at least 40 fMol/mg. On the basis of these experimental data and our EGF-R expression analysis of breast cancer specimens, we conclude that up to 15% of breast cancer patients could benefit from this monotherapy with EMD 55900.