FDA approves new treatment for a type of late-stage prostate cancer

FDA approved enzalutamide (Xtandi, Astellas Pharma U.S. Inc. and Medivation) to treat men with late-stage (metastatic) castration-resistant prostate cancer that has spread or recurred, even with medical or surgical therapy to minimize testosterone.

Approved for prostate cancer patients previously treated with docetaxel, another cancer treatment, Xtandi was reviewed under FDA’s priority review program. Xtandi received FDA approval 3 months ahead of the product’s prescription drug user fee goal date of Nov. 22, 2012.

“The need for additional treatment options for advanced prostate cancer continues to be important for patients,” said Richard Pazdur, MD, in a press release. Pazdur is director of the Office of Hematology and Oncology Products in FDA’s Center for Drug Evaluation and Research. “Xtandi is the latest treatment for this disease to demonstrate its ability to extend a patient’s life.”

Prostate cancer forms in a gland in the male reproductive system found below the bladder and in front of the rectum. The male sex hormone testosterone stimulates the prostate tumors to grow. According to the National Cancer Institute, an estimated 241,740 men will be diagnosed with prostate cancer and 28,170 will die from the disease in 2012.

The safety and effectiveness of Xtandi was evaluated in a study of 1,199 patients with metastatic castration-resistant prostate cancer who had received previous treatment with docetaxel. The study was designed to measure overall survival in men receiving Xtandi compared with men receiving a placebo. The median overall survival for patients receiving Xtandi was 18.4 months, compared with 13.6 months for the patients who received placebo.

The most common side effects observed in study participants taking Xtandi 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 high blood pressure.

Seizures occurred in approximately 1% of those receiving Xtandi. Patients in the study who had a seizure stopped Xtandi therapy. The clinical study excluded patients with a history of seizure, an underlying brain injury with loss of consciousness, a temporary decrease in blood to the brain within the past 12 months, a stroke, brain metastases, an abnormal connection of the arteries and veins in the brain, or patients taking medications that may lower the seizure threshold. The safety of Xtandi is unknown in patients with these conditions.