The development and clinical use of trastuzumab (Herceptin)
1Breast Unit, The Royal Marsden Hospital and Institute of Cancer Research, Fulham Rd, London SW3 6JJ, UK. mark.harries@rmh.nthames.nhs.uk
Abstract:
HER-2 is a member of the c-erbB family of receptor tyrosine kinases and is overexpressed by 20-30% of human breast cancers. HER-2 overexpression is an independent adverse prognostic factor and may also predict for response to both chemotherapy and endocrine agents. Trastuzumab is a humanised monoclonal antibody that binds with high affinity to the extracellular domain of HER-2. In HER-2-overexpressing preclinical models trastuzumab has been shown to have a marked antiproliferative effect and demonstrates synergy with a number of cytotoxic drugs. Several phase II and phase III clinical trials have now been performed in patients with advanced breast cancer that overexpress HER-2. Trastuzumab was initially shown to be active and well tolerated as a single agent in heavily pretreated women. Subsequently, studies of first-line treatment for metastatic breast cancer have demonstrated an improvement in survival for trastuzumab when used in combination with either paclitaxel or an anthracycline-cyclophosphamide regimen compared with chemotherapy alone. Unexpectedly, the combination of trastuzumab and the anthracycline-containing regimen was associated with a significant incidence of cardiac dysfunction. The benefit of trastuzumab is generally confined to patients whose tumours have gene amplification as detected by fluorescence in situ hybridisation (FISH) and this is tightly associated with immunohistochemical (IHC) staining at the highest (3+) level. A small number of patients have IHC 2+ tumours together with FISH evidence of gene amplification and may also derive benefit from treatment. Trastuzumab has also been shown to be effective when used as first-line monotherapy for advanced breast cancer. Trials to date have employed trastuzumab in a weekly schedule, but there is emerging evidence that a three-weekly regimen may be as effective. Trastuzumab has shown encouraging activity when used with other agents including docetaxel and vinorelbine. The combination of trastuzumab, docetaxel, and platinum salts also appears to be very active. The role of trastuzumab as adjuvant therapy for early breast cancer is being tested in a number of large randomised trials.
Insights
Trastuzumab is an effective treatment for HER-2-positive breast cancer, improving survival when combined with chemotherapy. Cardiac dysfunction is a risk, and efficacy is linked to HER-2 gene amplification detected by FISH and IHC testing.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- HER-2 (Human Epidermal growth factor Receptor 2) is a key protein in the c-erbB family of receptor tyrosine kinases.
- HER-2 overexpression occurs in 20-30% of human breast cancers, serving as an adverse prognostic factor.
- HER-2 status may predict response to chemotherapy and endocrine therapies.
Purpose of the Study:
- To evaluate the efficacy and safety of trastuzumab, a monoclonal antibody targeting HER-2, in HER-2-overexpressing breast cancer.
- To assess trastuzumab's role as a single agent and in combination with chemotherapy regimens.
- To investigate the predictive value of HER-2 gene amplification (FISH) and protein expression (IHC) for treatment response.
Main Methods:
- Review of preclinical data demonstrating trastuzumab's antiproliferative effects and synergy with cytotoxic drugs.
- Analysis of data from multiple Phase II and III clinical trials involving patients with advanced HER-2-overexpressing breast cancer.
- Correlation of treatment outcomes with HER-2 detection methods: immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).
Main Results:
- Trastuzumab demonstrated activity and tolerability as a single agent in heavily pretreated patients.
- Combination therapy with trastuzumab and paclitaxel or anthracycline-cyclophosphamide improved survival compared to chemotherapy alone in first-line metastatic breast cancer.
- A significant incidence of cardiac dysfunction was observed with trastuzumab combined with anthracycline-containing regimens.
- Treatment benefit was primarily observed in patients with HER-2 gene amplification (FISH-positive) and high IHC staining (3+).
- Patients with IHC 2+ tumors and FISH-positive results may also benefit.
- Trastuzumab showed efficacy as first-line monotherapy and encouraging activity with other agents like docetaxel and vinorelbine.
Conclusions:
- Trastuzumab is an effective targeted therapy for HER-2-overexpressing breast cancer, significantly improving outcomes in advanced disease.
- HER-2 gene amplification (FISH) and high protein expression (IHC 3+) are key predictive biomarkers for trastuzumab efficacy.
- Careful monitoring for cardiac dysfunction is essential, particularly when used in combination regimens.
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