The FDA expedited the approval of the androgen inhibitor enzalutamide (Xtandi; Astellas Pharma/Medivation) for the treatment of metastatic castration-resistant prostate cancer (CRPC) that has spread or recurred in patients previously treated with docetaxel chemotherapy or with surgery. Enzalutamide is designed to interfere with the ability of testosterone to bind to prostate cancer cells.
Enzalutamide was approved 3 months ahead of its scheduled review. The approval was based on a study of 1199 patients with metastatic CRPC who had received previous treatment with docetaxel. The median overall survival was 18.4 months for patients receiving enzalutamide compared with 13.6 months with placebo.
The most common side effects were weakness or fatigue, back pain, diarrhea, joint pain, hot flush, tissue swelling, musculoskeletal pain, headache, upper respiratory infections, dizziness, spinal cord compression and cauda equina syndrome, muscular weakness, difficulty sleeping, lower respiratory infections, blood in urine, tingling sensation, anxiety, and hypertension. Approximately 1% of those receiving enzalutamide had a seizure and stopped taking it.
Enzalutamide is currently being tested in patients with early-stage prostate cancer. (August 31, 2012)
