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Human epidermal growth factor receptor-2 and hormonal therapies: clinical implications
1Department of Academic Biochemistry, Wallace Wing, Royal Marsden Hospital, London, United Kingdom.
Abstract:
Estrogen-targeted therapies such as administration of tamoxifen or aromatase inhibitors are among the most important treatment strategies in the modern management of breast cancer. Despite initial responses in the metastatic setting and prolonged disease-free intervals in the adjuvant setting, many patients subsequently become resistant to these agents. Human epidermal growth factor receptor-2 (HER2) is a transmembrane glycoprotein receptor that is overexpressed in 13%-30% of human breast cancers. There are experimental data suggesting an important role for HER2 in de novo and acquired resistance to endocrine therapies. These experimental data are discussed in this article, as are clinical data addressing the role of HER2 in resistance to endocrine therapy in the adjuvant, neoadjuvant, and metastatic settings. Responses and benefit from tamoxifen appear to be impaired in patients in whom HER2 is overexpressed. In contrast, early data from the neoadjuvant setting suggest that responses to aromatase inhibitors may be maintained in patients with HER2 overexpression.
Insights
Human epidermal growth factor receptor-2 (HER2) overexpression can lead to resistance to estrogen-targeted therapies like tamoxifen in breast cancer. However, aromatase inhibitors may maintain treatment response in patients with HER2 overexpression.
Area of Science:
- Oncology
- Molecular Biology
- Endocrinology
Background:
- Estrogen-targeted therapies (tamoxifen, aromatase inhibitors) are crucial for breast cancer management.
- Acquired resistance to these endocrine therapies is a significant clinical challenge.
- Human epidermal growth factor receptor-2 (HER2) overexpression is observed in 13%-30% of breast cancers.
Purpose of the Study:
- To review experimental and clinical data on the role of HER2 in endocrine therapy resistance in breast cancer.
- To evaluate the impact of HER2 status on treatment response to tamoxifen and aromatase inhibitors across different clinical settings.
Main Methods:
- Review of experimental studies investigating HER2's role in endocrine resistance.
- Analysis of clinical data from adjuvant, neoadjuvant, and metastatic breast cancer settings.
- Correlation of HER2 overexpression with treatment outcomes for tamoxifen and aromatase inhibitors.
Main Results:
- Experimental data suggest HER2 plays a role in both de novo and acquired resistance to endocrine therapies.
- Clinical data indicate impaired response and benefit from tamoxifen in HER2-overexpressing breast cancers.
- Preliminary neoadjuvant data suggest aromatase inhibitor efficacy may be preserved in HER2-overexpressing tumors.
Conclusions:
- HER2 overexpression is associated with tamoxifen resistance in breast cancer.
- Aromatase inhibitors might offer a viable treatment option for HER2-overexpressing breast cancer patients.
- Further research is warranted to elucidate HER2's complex role in endocrine therapy resistance.