The Food and Drug Administration (FDA) has approved a novel prostate cancer drug in patients whose cancer has spread despite treatment with hormone therapy and chemotherapy. Enzalutamide, a pill developed by Medivation Inc. and Astellas Pharma Inc, will be sold under the brand name Xtandi.
Xtandi is in a new class of drugs known as androgen inhibitors and is designed to interfere with the ability of testosterone to bind to prostate cancer cells. Testosterone encourages growth of prostate cancer cells. The drug was approved three months before the agency’s late-November deadline.
A pivotal study on Xtandi was stopped early when data showed that the pill improved the median overall survival of patients with metastatic prostate cancer by 4.8 months compared to placebo. The drug is also being tested in men with earlier stages of the disease, and while results of that study are pending, researchers say the drug may be beneficial as a pre-chemotherapy agent for some patients.
Last year the FDA approved Johnson & Johnson’s Zytiga which works in cancer cells to block testosterone production. Analysts say Xtandi is expected to have higher sales than Zytiga because clinical trials of Xtandi show it has better efficacy and almost no serious side effects.
Adverse reactions reported with Xtandi include weakness, fatigue and back pain. Seizures were reported in about one percent of patients. The FDA’s approval of the drug requires the drug companies to conduct a post-marketing study of the drug to determine seizure risk.
Medivation and Astellas have also filed for regulatory approval in Europe.