Combination Therapy Shows Promise for Treating Advanced Breast Cancer

Adapted from the NCI Cancer Bulletin.

Adding the drug everolimus (Afinitor®) to exemestane helped postmenopausal women whose advanced breast cancer had stopped responding to hormonal therapy live about 4 months longer without the disease progressing than women who received exemestane alone. Findings from the trial, called BOLERO 2, were presented at the San Antonio Breast Cancer Symposium.

For women who received the combination therapy, the median progression-free survival was 7.4 months compared with 3.2 months for those who received exemestane alone, Gabriel Hortobagyi, M.D., of the University of Texas M. D. Anderson Cancer Center reported at the symposium. These were the latest available data, updated from preliminary results presented at the European Multidisciplinary Cancer Congress in September and results published online December 7, 2011 in the New England Journal of Medicine (NEJM).

The researchers do not yet have data on whether the combination therapy improves overall survival, but they expect to have it in late 2012. In July, the randomized phase of BOLERO 2 was stopped early after an interim analysis showed an improvement in progression-free survival. The study, which was supported by Novartis, the manufacturer of Afinitor, included many participants who had previously received multiple therapies.

Everolimus inhibits a protein called mTOR, which plays a role in a signaling pathway that promotes cell growth and proliferation. Exemestane, an aromatase inhibitor, is used to treat metastatic breast cancer.

“For postmenopausal patients with hormone receptor-positive metastatic breast cancer, the addition of everolimus to exemestane markedly improves the duration of disease control,” Dr. Hortobagyi said in a statement. This benefit should be weighed against the side effects associated with everolimus, such as fatigue and oral mucositis, the study authors noted in the NEJM article.