Afinitor Impresses in Advanced Breast Cancer

Afinitor (exemestane) and an aromatase inhibitor delay cancer growth in metastatic breast cancer.

One of the most anticipated presentations at the 2011 San Antonio Breast Cancer Symposium was on a phase 3 study of Afinitor (everolimus) plus Aromasin (exemestane) for treating postmenopausal women with advanced estrogen-positive breast cancer.

The study followed 724 patients with progressing hormone-positive metastatic breast cancer. All women in the trial were receiving either anastrozole or letrozole, both aromatase inhibitors.

The trial was halted in February when it became apparent the Afinitor combination was better than Aromasin alone. Preliminary data showed that with the addition of Afinitor, progression-free survival (PFS) improved from 2.8 months to 6.9. After a year follow-up, PFS had improved from 3.2 months in the Aromasin arm to 7.4 months in the Aromasin and Afinitor arm, an improvement of about 57 percent. Response rates also doubled from 25.5 to 50.5 percent, which included complete and partial responses, as well as stable disease lasting at least six months.

“These results establish a new standard of care for this group of patients,” says Gabriel N. Hortobagyi, MD, director of the Breast Cancer Research Program at the M.D. Anderson Cancer Center in Houston.