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Hormonal Therapy and Antiangiogenic Therapy
Up to 70% of patients with estrogen receptor-positive (ER-positive) breast cancer initially benefit from hormone therapy. A sizable percentage of patients, however, will become resistant to these treatments. Excessive angiogenesis may contribute to the development of resistance to hormone therapy in breast cancer patients with ER-positive tumors.12

Two recent clinical studies evaluated the safety and effectiveness of combining hormone therapy with antiangiogenic drugs. The first of these combined bevacizumab with letrozole (Femara®), a hormone therapy approved for use in postmenopausal women with early stage, hormone receptor-positive breast cancer following surgery. The study, which looked only at the safety of the drug combination, enrolled postmenopausal women with locally advanced or metastatic ER-positive breast cancer.13 The therapy was generally well tolerated, although some patients developed excess protein in the urine. A phase 3 clinical trial combining hormone therapy (letrozole or tamoxifen) with bevacizumab is underway.

Another small study combined sorafenib with the hormone therapy anastrozole (Arimidex®) in postmenopausal women with ER- and progesterone (PR) positive tumors.14 The participants in this study were resistant to prior hormone therapy. At follow-up, 20% of patients had some clinical benefit from the sorafenib-anastrozole combination. Five patients had their tumors stop growing for more than 24 weeks, and two patients experience tumor shrinkage for more than 6 months.


Last updated May 29, 2011