Exemestane in advanced breast cancer

Exemestane is an orally active steroidal aromatase inhibitor that has demonstrated efficacy in the treatment of postmenopausal patients with advanced breast cancer. This compound exhibits a good tolerability and safety profile, which may result from its highly selective mechanism of action. Exemestane binds irreversibly to the aromatase enzyme causing inactivation of the enzyme. This irreversible loss of enzyme may contribute to the sustained inhibition of estrogen synthesis noted following exemestane administration. Exemestane is a potent inhibitor of aromatization reducing estrogen synthesis in vivo by greater than 97%. The recommended dose of exemestane is 25 mg once daily. Although dosages up to 600 mg/day have been tested, the maximum tolerated dose of exemestane has not been reached in clinical study. The most frequently reported drug-related adverse events are hot flushes, nausea and fatigue, which are consistent with the estrogen-suppressive effects of the drug. Discontinuation due to adverse events is rare. Exemestane is a safe and well-tolerated alternative for the treatment of postmenopausal patients with advanced breast cancer.