Exemestane

Exemestane is a steroidal agent which causes inactivation of the aromatase enzyme by binding irreversibly to the substrate binding site. Oral exemestane 25 mg/day inactivates peripheral aromatase activity (simila r to 98% inactivation) and reduces basal plasma estrone, estradiol and estr one sulphate levels by 85 to 95% in postmenopausal women with advanced brea st cancer. Phase II trials indicate that oral exemestane 25 mg/day is an effective sec ond- or third-line agent in the treatment of postmenopausal women with adva nced breast cancer (achieving an objective response in up to 28 and 26% of patients, respectively). Results from a phase III trial indicate that exemestane achieves a similar objective response rate to megestrol as a second-line therapy; however, exe mestane achieved a significantly longer duration of overall success, time t o disease progression and survival time. Exemestane is at least as well tolerated as megestrol, but is associated wi th significantly fewer bodyweight changes, mainly bodyweight gain (greater than or equal to 10%). Other common adverse events are hot flushes, nausea and fatigue.