The Food and Drug Administration (FDA) has approved enzalutamide (Xtandi) to treat men with advanced prostate cancer that has spread or recurred after medical or surgical therapy to minimize testosterone, which fuels tumor growth. The drug was approved for use in prostate cancer patients previously treated with docetaxel.
The safety and effectiveness of enzalutamide—previously called MDV3100—was evaluated in a study of 1,199 patients with metastatic castration-resistant prostate cancer who had received prior treatment with docetaxel. The median overall survival for patients who received enzalutamide was 18.4 months, compared with 13.6 months for those who received a placebo.
The most common side effects were fatigue, back pain, diarrhea, joint pain, hot flush, tissue swelling, musculoskeletal pain, respiratory infections, dizziness, spinal cord compression, blood in urine, tingling sensation, anxiety, and high blood pressure.
Seizures occurred in about 1 percent of those receiving enzalutamide. Study participants who had a seizure stopped enzalutamide therapy. The clinical study excluded men who had a history of seizure or several other brain conditions or who were taking medications that may cause seizures. The safety of enzalutamide in patients with these conditions is unknown.
Enzalutamide was reviewed under the FDA’s priority review program, which allows an expedited 6-month review for drugs that may offer major advances in treatment or that provide a treatment when no adequate therapy exists.