The FDA reviewed Xtandi under its Priority Review Program, which allows medications to be reviewed within just six months. This type of accelerated program is reserved for drugs that have the potential to offer major treatment advances, or medications for which no proper therapy exists. According to the FDA in an online communiqué "Xtandi received FDA approval three months ahead of the product's prescription drug user fee goal date of Nov. 22, 2012".
Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products, Center for Drug Evaluation and Research, FDA, said:
"The need for additional treatment options for advanced prostate cancer continues to be important for patients. Xtandi is the latest treatment for this disease to demonstrate its ability to extend a patient's life."
FDA scientists evaluated Xtandi's efficacy and safety by assessing data from a clinical trial involving 1,199 men with metastatic castration-resistant prostate cancer who had previously received docetaxel. The study's primary endpoint was to measure how long each patient survived (overall survival) - the patients had been randomly selected to receive either Xtandi or a dummy drug (placebo).
The trial showed that those in the Xtandi group survived for an average of 18.4 months, compared to 13.6 months in the placebo group.
Side effects - reported side-effects linked to Xtandi therapy included back pain, headache, upper respiratory infections, hypertension, anxiety, tingling, blood in urine, lower respiratory infections, musculoskeletal pain, tissue swelling, hot flushes, joint pain, diarrhea, fatigue, and weakness.
Approximately 1% of patients on Xtandi had at least one seizure; they were immediately taken off the drug.
The clinical trial had no patients with a history of seizure, stroke, brain metastasis, those on medications which may increase seizure risk, a temporary drop in blood supply to the brain, or any underlying brain injury with loss of consciousness. The FDA said that Xtandi's safety with these patients is unknown.
Xtandi will be manufactured and sold by two companies, Astellas Pharma US Inc., and Medivation Inc.
Charles Sawyers and Michael Jung discovered enzalutamide, which was developed by Medivation Inc. According the company, the drug reported up to an 89% decrease in prostate specific antigen serum levels within a month of treatment in 3 clinical trials. Preliminary clinical studies also indicate that enzalutamide slows down breast cancer cell growth.
The two companies say Xtandi should be available to patients in the USA in mid-September 2012. Medivation says Xtandi has also been submitted for review to EMA (the European Medicines Agency).
David Hung, M.D., co-founder, president and CEO of Medivation, Inc., said:
"Today's approval marks a significant accomplishment for Medivation. We are proud to be in a position to offer a new treatment, XTANDI, for this patient population for which there is a significant unmet medical need. I would like to extend my thanks to the patients, physicians, and their study teams who participated in the clinical trials, and to our employees, and those of our partner Astellas, who have been instrumental in helping us reach this important milestone."
Howard I. Scher, M.D., chief, Genitourinary Oncology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, Memorial Sloan-Kettering Cancer Center, and co-leader of one of the Xtandi pivotal studies, called "AFFRIM", said that "Enzalutamide provides an exciting new option for physicians that can prolong the lives of patients with metastatic prostate cancer who have received chemotherapy. It is extremely gratifying to have led the clinical trial of enzalutamide, having followed the development of this drug from its early inception in the laboratory to the clinic."
Stephen Eck, M.D., Ph.D., Vice President of Medical Oncology, Astellas Pharma Global Development, said:
"We believe Xtandi has the potential to play an important role in the treatment of advanced prostate cancer. We're eager to work with Medivation to make this much-needed new treatment available to medical professionals and patients in September."
Xtandi, an androgen receptor inhibitor, is taken orally, once a day, in four 40mg capsules (160 mg per day). It can be taken during or before meals and does not require concomitant prednisone. 48% of patients given Xtandi in the phase 3 trial were treated with glucocorticoids.
Written by Christian Nordqvist