Results from two randomized studies titled “Trastuzumab Plus Adjuvant Chemotherapy for Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer: Planned Joint Analysis of Overall Survival From NSABP B-31 and NCCTG N9831” and published in the Journal of Clinical Oncology, showed that combining trastuzumab (Herceptin) with chemotherapy can significantly improve the overall and disease-free survival of women with early stage HER2-positive breast cancer.
Around 15 to 20% of all invasive breast cancers are diagnosed as HER2-positive. Before Herceptin (a monoclonal antibody targeting the HER2/neu receptor) was developed, women diagnosed with HER2-negative breast cancer had a better prognosis than those with early stage breast cancer who showed faster relapse, higher incidence of metastasis, and shorter survival.
“This long follow-up of patients shows that we have really altered the natural history of this disease. Herceptin works — and it works for a long period of time. The drug has impacted the lives of many women in the U.S. and worldwide,” lead author Dr. Edith A. Perez, M.D., deputy director at large, Mayo Clinic Cancer Center and director of the Breast Cancer Translational Genomics Program at Mayo Clinic in Florida, said in a Mayo news release.
The two long-term randomized phase III studies, N9831, led by the North Central Cancer Treatment Group (NCCTG) Alliance, and NRG B-31, led by the National Surgical Adjuvant Breast and Bowel Project, were responsible for Herceptin’s approval in the treatment of early stage HER2-positive breast cancer by the U.S. Food and Drug Administration (FDA).
In these studies, a total of 4,046 patients received doxorubicin plus cyclophosphamide (chemotherapeutic drugs), however, while one half received paclitaxel (mitotic inhibitor used in chemotherapy) with trastuzumab, the other half were treated with paclitaxel alone.
The results demonstrated that while both subgroups had an improved overall and disease-free survival (including patients with node-positive and node-negative cancers, as well as estrogen-positive and estrogen-negative cancers), adding trastuzumab as part of the treatment resulted in a 37% increased survival and 40% reduction of cancer recurrence.
Furthermore, the results confirmed the long-term safety profile of trastuzumab, since patients followed for a period of 8 years had no increase in secondary cancer incidence, and only presented a minor increase in heart complications.
While trastuzumab was first used for the treatment of metastatic HER2-positive breast cancer, it is now commonly used to treat patients suffering from early stage HER2-positive breast cancer.