Among women with advanced HER2-positive breast cancer and resistance to Herceptin® (trastuzumab), a treatment regimen that included Afinitor® (everolimus) delayed cancer progression. The results of this Phase III clinical trial were presented at the 2013 Annual Meeting of the American Society of Clinical Oncology (ASCO).
Afinitor is an oral medication that works by inhibiting a protein known as mTOR. The mTOR protein plays an important role in regulating cancer cell division and blood vessel growth. Currently, Afinitor is used for the treatment of selected patients with kidney cancer, pancreatic neuroendocrine tumors, subependymal giant cell astrocytoma (SEGA), renal angiomyolipoma, and hormone receptor-positive/HER2-negative breast cancer.
To evaluate Afinitor among women with advanced HER2-positive breast cancer, researchers conducted a Phase III clinical trial known as BOLERO-3. The study enrolled 569 women with HER2-positive, locally advanced or metastatic breast cancer. All of the study participants had received prior treatment with a taxane chemotherapy drug, and all were resistant to Herceptin.
The study assigned women to one of two treatment groups: 1) vinorelbine, Herceptin, and Afinitor, or 2) vinorelbine, Herceptin, and placebo.
- Progression-free survival (survival without a worsening of the cancer) was 7 months in the Afinitor group and 5.8 months in the placebo group.
- Common side effects included low blood cell counts, mouth sores (stomatitis), fatigue, fever, diarrhea, nausea, decreased appetite, and constipation.
- Overall survival results require longer-follow-up.
Afinitor had already been shown to benefit certain women with HER2-negative breast cancer, and the results of the current study show that it can also provide a benefit in advanced HER2-positive breast cancer.
Reference: O’Regan R, Ozguroglu M, Andre F et al. Phase III, randomized, double-blind, placebo-controlled multicenter trial of daily everolimus plus weekly trastuzumab and vinorelbine in trastuzumab-resistant, advanced breast cancer (BOLERO-3). Presented at the 49th Annual Meeting of the American Society of Clinical Oncology. May 31-June 4, 2013; Chicago, IL. Abstract 505.
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