Afinitor Boosts Effectiveness of Hormonal Therapy

Adding Afinitor (everolimus) to tamoxifen helped women with metastatic breast cancer live four months longer without their disease getting worse, according to a study presented Thursday at the San Antonio Breast Cancer Symposium.

Researchers randomly assigned 111 women to receive tamoxifen alone or tamoxifen plus Afinitor. Patients getting the combination lived a median of 8.6 months without disease progression, compared with 4.5 months for the tamoxifen-only group. After a median follow-up of around 22 months, nine patients in the combination arm had died compared with 25 deaths in the tamoxifen arm. All patients in this phase 2 trial had estrogen receptor–positive breast cancer that had previously been treated with an aromatase inhibitor, like Femara (letrozole) or Arimidex (anastrozole).

Afinitor—already approved for advanced kidney cancer—works by targeting mTOR, a protein that helps regulate the growth of cancer cells and blood vessels. Side effects associated with Afinitor include mouth ulcers, infections, cough and fatigue.

Three phase 3 studies, nicknamed BOLERO—short for Breast cancer trials of OraL EveROlimus— are now under way testing Afinitor in patients with locally advanced or metastatic breast cancer. one study will look at Afinitor in combination with the HER2-targeted drug Herceptin (trastuzumab) and the chemotherapy drug Taxol (paclitaxel). A second study will test the mTOR inhibitor in combination with Aromasin (exemestane), an aromatase inhibitor used to treat postmenopausal women with estrogen receptor–positive breast cancer. The third study will combine Afinitor with Herceptin and vinorelbine, a chemotherapy agent.