The FDA has approved the androgen receptor signaling blocker enzalutamide (Xtandi) for the treatment of patients with destructive-resistant prostate cancer. enzalutamide is indicated for men with disease progression after docetaxel treatment and is in the FDA’s priority review process. Richard Pazdur, M.D., director of the FDA’s Division of Hematology and Oncology Drugs, said in his report, “The need for increased treatment options for patients with advanced prostate cancer remains important. Xtandi has been shown to extend patient survival, and it is the newest treatment option. Pazdur’s comments refer to vaccine (Provenge), cabazitaxel, and abiraterone, which were all approved from 2010 by the FDA for the treatment of debulking-resistant prostate cancer. As reported in a previous article this month, in a large randomized clinical trial of enzalutamide compared to placebo for patients with desmoresistant prostate cancer, the former achieved an overall survival time of more than 5 months. The results of this study validation were reported at the ASCO meeting in June. The most common side effects reported in association with enzalutamide include: weakness or fatigue, back pain, diarrhea, arthralgia, hot flashes, edema, muscle pain, headache, upper respiratory tract infection, dizziness, spinal cord compression, muscle fatigue, anxiety, hematuria, hypertension, and tingling sensation. Enzalutamide is a new generation anti-androgen drug that blocks androgen receptor signaling at multiple points in the signaling pathway. Compared to conventional androgen antagonists, enzalutamide has no competitive effect at the androgen receptor.