Exemestane Produces Responses After Prior Aromatase Agents

Exemestane Produces Responses After Prior Aromatase Agents

According to results presented at the 2003 San Antonio Breast Cancer Symposium, the aromatase agent exemestane (Aromasin ®) produces anti-cancer responses in postmenopausal women with metastatic breast cancer that has stopped responding to other aromatase inhibitors.

Breast cancer is diagnosed in over 200,000 women annually in the United States alone. Although cure rates are high if breast cancer is diagnosed and treated prior to the spread of cancer, long-term survival remains dismal among most patients with cancer that has spread to distant sites in the body, referred to metastatic breast cancer. One common type of breast cancer is referred to as hormone-positive breast cancer. This type of breast cancer is stimulated to grow by the common female hormones estrogen and/or progesterone. Patients with hormone-positive breast cancer are treated with therapy referred to as hormone therapy that typically consists of agents that either block the production of estrogen in a body, or block the growth-stimulatory effects of estrogen on a cell. Historically, the agent tamoxifen (Nolvadex ®), which blocks estrogen from being able to bind to a cell, was the standard drug used as hormone therapy in breast cancer. More recently, a newer class of agents, referred to as aromatase agents, have entered the clinical setting for treatment of postmenopausal women with hormone-positive breast cancer. Several clinical trials are ongoing to determine the optimal sequencing and duration of treatment of the different hormone agents.

Researchers from England recently reviewed data evaluating the aromatase agent exemestane in the treatment of postmenopausal, hormone-positive breast cancer that had stopped responding to prior aromatase agents. The data included 96 patients who had been treated with either 1, 2, or 3 prior hormone agents, including at least one aromatase agent. Exemestane produced clinical benefit (anti-cancer responses or disease stabilization) in nearly 40% of patients. The average time to cancer progression while on exemestane was approximately 4 months, and the average survival time from initiation of exemestane was 55 weeks for the entire group of patients. However, patients who achieved a clinical benefit from exemestane had not yet reached the average duration of survival at the time of publication of this trial. Furthermore, the number of prior hormone therapies did not significantly affect time to cancer progression and overall survival in these patients.

The researchers concluded that exemestane appears to provide clinical benefit in postmenopausal women with metastatic, hormone-positive breast cancer that has stopped responding to previous hormone therapy, including prior aromatase agents. Postmenopausal women with hormone-positive breast cancer that has stopped responding to hormone therapy may wish to speak with their physician about the risks and benefits of exemestane or the participation in a clinical trial evaluating other hormonal agents or therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute ( cancer.gov) and www.cancerconsultants.com. Personalized clinical trial searches are also performed on behalf of patients at cancerconsultants.com.

Reference: Fernie N, Zekri J, Leonard R, et al. Exemestane in metastatic breast cancer: effective therapy after 3rd generation aromatase inhibitor failure. Proceedings from the 26th annual San Antonio Breast Cancer Symposium. December 2003. Abstract #435.

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