Antiandrogen for prostate cancer shows improvement in survival, quality of life

Chicago-Men with previously treated castration-resistant prostate cancer (CRPC) lived almost 5 months longer when they received the androgen receptor signaling inhibitor enzalutamide, data from an international study showed.

The secondary endpoints of time to first skeletal-related event and health-related quality of life were also significantly improved in enzalutmide-treated patients versus placebo.

"[Enzalutamide] is well tolerated and prolongs survival and improves quality of life across the board, making better all secondary measures of health-related outcomes and antitumor activity."

Data were presented at the American Society of Clinical Oncology annual meeting in Chicago and recently published online in the New England Journal of Medicine (Aug. 15, 2012).

Enzalutamide targets androgen receptor signaling and affects multiple steps in the signaling pathway. The agent has shown no agonistic effect on the androgen receptor in preclinical models. Development of the drug has evolved amid growing recognition that a substantial proportion of men with advanced prostate cancer benefit from second-line hormonal therapy.

Phase I-II investigation of enzalutamide demonstrated activity in patients with and without prior exposure to chemotherapy. A majority of patients had PSA responses irrespective of chemotherapy history (Lancet 2010; 375:1437-46). The promising results from early studies led to a phase III, randomized, placebo-controlled trial conducted at 156 centers in 15 countries on five continents. The study involved 1,199 patients with progressive CRPC after treatment with docetaxel (Taxotere).

The patients were randomized 2:1 to either oral enzalutamide, 160 mg/day, or matched placebo. Treatment continued until radiographic evidence of progression by bone scan.

"This is an important change for us with both the abiraterone and MDV3100 trials," said Dr. de Bono. "The overall aim was to continue therapy despite minor PSA changes. This is very important for clinical practice not to change therapy purely based on PSA changes."