According to the results of a Phase II clinical trial, the addition of the investigational drug RAD001 (everolimus) to Femara® (letrozole) enhanced tumor shrinkage among postmenopausal women with hormone receptor-positive breast cancer.
Each year breast cancer is diagnosed in close to 200,000 women in the United States alone. Many of these breast cancers will be hormone receptor-positive, meaning that they are stimulated to grow by the circulating female hormones estrogen and/or progesterone.
Treatment of hormone receptor-positive breast cancer often involves hormonal therapies that suppress or block the action of estrogen. These therapies include tamoxifen [Nolvadex®] as well as agents known as aromatase inhibitors. Tamoxifen acts by blocking estrogen receptors, whereas aromatase inhibitors- such as Femara-suppress the production of estrogen.
RAD001 is an oral targeted therapy 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.
To explore whether RAD001 enhances the response to Femara in the neoadjuvant (before surgery) setting, researchers conducted a Phase II clinical trial among 270 postmenopausal women with hormone receptor-positive breast cancer. Half the women received Femara plus RAD001, and half the women received Femara alone.
- Evidence of tumor shrinkage was found in 68% of women treated with Femara plus RAD001 compared with 59% of women treated with Femara alone.
- Serious (grade 3 or grade 4) adverse effects of treatment were more common in patients treated with Femara plus RAD001 (23%) than among patients treated with Femara alone (4%). Serious adverse effects among patients treated with Femara plus RAD001 included high blood sugar, mouth sores, pneumonitis (inflammation of the lungs), and infections.
These results suggest that RAD001 may improve the efficacy of Femara in newly diagnosed, hormone receptor-positive breast cancer. Women who have been diagnosed with breast cancer may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating this or other promising therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and eCancerTrials (www.ecancertrials.com).
Reference: Baselga J, van Dam PA, Greil R et al. Improved clinical and cell cycle response with an mTOR inhibitor, daily oral RAD001 (everolimus) plus letrozole versus placebo plus letrozole in a randomized Phase II neoadjuvant trial in ER+ breast cancer. Proceedings from the 44th annual meeting of the American Society of Clinical Oncology. Chicago, IL. 2008. Abstract #530.