New England Journal of Medicine Publishes Results from Phase 3 PREVAIL Trial of Enzalutamide in Men with Chemotherapy-Naive Metastatic Prostate Cancer Progressing Despite Androgen Deprivation Therapy

NORTHBROOK, Ill. and SAN FRANCISCO, JUNE 1, 2014 /PRNewswire/ -- Astellas Pharma US, Inc., a U.S. subsidiary of Tokyo-based Astellas Pharma Inc. (Tokyo: 4503) and Medivation, Inc. (Nasdaq: MDVN) today announced the online publication in the New England Journal of Medicine of the results from the Phase 3 PREVAIL trial, an international, randomized, double-blind, placebo-controlled clinical study of enzalutamide. The study evaluated the benefit and safety of enzalutamide in men with metastatic prostate cancer, who had few or no symptoms, that had progressed on luteinizing hormone-releasing hormone (LHRH) therapy or after bilateral orchiectomy. The paper, "Enzalutamide in Men with Metastatic Prostate Cancer Before Chemotherapy," appears in the June 1 online issue and the companies anticipate publication in a future print issue of the Journal.

"The PREVAIL study results demonstrate that treatment with enzalutamide in men with metastatic castration resistant prostate cancer can decrease the risk of death, delay the growth or spread of metastatic prostate cancer, and delay the time to initiation of chemotherapy," said Tomasz M. Beer, M.D., F.A.C.P., professor of medicine and deputy director of the Knight Cancer Institute at Oregon Health & Science University, and co-principal investigator of the PREVAIL study. "We are delighted that the New England Journal of Medicine has chosen to publish these important results."

A supplemental New Drug Application (sNDA) based on the PREVAIL results received a priority review designation from the U.S. Food and Drug Administration (FDA).  The Prescription Drug User Fee Act (PDUFA) goal date is September 18, 2014. A variation application to amend the European Marketing Authorization Application based on the results of PREVAIL was validated for review by the European Medicines Agency on April 24, 2014.

About the PREVAIL Trial
The Phase 3 PREVAIL trial is a randomized, double-blind, placebo-controlled, multi-national trial that enrolled more than 1,700 patients at sites in the United States, Canada, Europe, Australia, Russia, Israel and Asia including Japan. The trial enrolled patients with chemotherapy-naive metastatic prostate cancer whose disease progressed on androgen deprivation therapy (i.e., a luteinizing hormone-releasing hormone (LHRH) therapy or after bilateral orchiectomy). The co-primary endpoints of the trial were overall survival and radiographic progression-free survival. The trial was designed to evaluate enzalutamide at a dose of 160 mg taken orally once daily versus placebo.   

In the PREVAIL trial, men treated with enzalutamide demonstrated a statistically significant delay in cancer progression and reduction in the risk of death compared with placebo.

Enzalutamide reduced the risk of radiographic progression or death by 81% (HR=0.19; p < 0.0001), compared with placebo. The rate of radiographic progression-free survival at 12 months of follow up was 65% among patients treated with enzalutamide, as compared with 14% among patients receiving placebo.

Enzalutamide reduced the risk of death by 29% (HR=0.71; p < 0.0001), compared with placebo.  A total of 626 patients (72%) in the enzalutamide group, as compared with 532 patients (63%) in the placebo group, were alive at the September 16, 2013 data cutoff date.

The most common clinically relevant adverse events associated with enzalutamide treatment as compared with placebo-treated patients in the PREVAIL trial included fatigue, hot flush and hypertension; hypertension was observed in 13.4% of enzalutamide versus 4.1% of placebo-treated patients. Grade 3 or higher cardiac adverse events were reported in 2.8% of enzalutamide versus 2.1% of placebo-treated patients. One patient experienced a seizure in each treatment group.

Enzalutamide Mechanism of Action
Enzalutamide is an androgen receptor inhibitor that acts on different steps in the androgen receptor signaling pathway. Enzalutamide has been shown to competitively inhibit androgen binding to androgen receptors, and inhibit androgen receptor nuclear translocation and interaction with DNA.

About XTANDI® (enzalutamide) capsules
XTANDI was approved by the FDA on August 31, 2012 and is indicated for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) who have previously received docetaxel. In March 2014, Astellas and Medivation submitted a sNDA to the  FDA seeking approval of XTANDI for the treatment of men with metastatic prostate cancer that has progressed on LHRH therapy or after bilateral orchiectomy. In May 2014, the FDA granted the sNDA application Priority Review designation with a PDUFA date of September 18, 2014.

Important Safety Information for XTANDI (from the approved prescribing information) Contraindications: XTANDI can cause fetal harm when administered to a pregnant woman based on its mechanism of action. XTANDI is not indicated for use in women. XTANDI is contraindicated in women who are or may become pregnant.

Warnings and Precautions: In the randomized clinical trial, seizure occurred in 0.9% of patients on XTANDI. No patients on the placebo arm experienced seizure. Patients experiencing a seizure were permanently discontinued from therapy. All seizures resolved. Patients with a history of seizure, taking medications known to decrease the seizure threshold, or with other risk factors for seizure were excluded from the clinical trial. Because of the risk of seizure associated with XTANDI use, patients should be advised of the risk of engaging in any activity where sudden loss of consciousness could cause serious harm to themselves or others.

Adverse Reactions: The most common adverse drug reactions (>/= 5%) reported in patients receiving XTANDI in the randomized clinical trial were asthenia/fatigue, back pain, diarrhea, arthralgia, hot flush, peripheral edema, musculoskeletal pain, headache, upper respiratory infection, muscular weakness, dizziness, insomnia, lower respiratory infection, spinal cord compression and cauda equina syndrome, hematuria, paresthesia, anxiety, and hypertension. Grade 1-4 neutropenia occurred in 15% of XTANDI patients (1% Grade 3-4) and in 6% on placebo (no Grade 3-4). Grade 1-4 elevations in bilirubin occurred in 3% of XTANDI patients and 2% on placebo. One percent of XTANDI patients compared to 0.3% on placebo died from infections or sepsis. Falls or injuries related to falls occurred in 4.6% of XTANDI patients versus 1.3% on placebo. Falls were not associated with loss of consciousness or seizure. Fall-related injuries were more severe in XTANDI patients and included non-pathologic fractures, joint injuries, and hematomas. Grade 1 or 2 hallucinations occurred in 1.6% of XTANDI patients and 0.3% on placebo, with the majority on opioid-containing medications at the time of the event.

Drug Interactions - Effect of Other Drugs on XTANDI: Administration of strong CYP2C8 inhibitors can increase the plasma exposure to XTANDI. Co-administration of XTANDI with strong CYP2C8 inhibitors should be avoided if possible. If co-administration of XTANDI cannot be avoided, reduce the dose of XTANDI. Co-administration of XTANDI with strong or moderate CYP3A4 and CYP2C8 inducers can alter the plasma exposure of XTANDI and should be avoided if possible.

Effect of XTANDI on Other Drugs: XTANDI is a strong CYP3A4 inducer and a moderate CYP2C9 and CYP2C19 inducer in humans. Avoid CYP3A4, CYP2C9 and CYP2C19 substrates with a narrow therapeutic index, as XTANDI may decrease the plasma exposures of these drugs. If XTANDI is co-administered with warfarin (CYP2C9 substrate), conduct additional INR monitoring.

For Full Prescribing Information for XTANDI (enzalutamide) capsules, please visit www.XtandiHCP.com.

About Astellas Pharma Inc.
Astellas Pharma Inc. is a pharmaceutical company dedicated to improving the health of people around the world through provision of innovative and reliable pharmaceuticals. The organization is committed to being a global category leader in Oncology and Urology, and has several oncology compounds in development in addition to enzalutamide. For more information on Astellas Pharma Inc., please visit our website at www.astellas.com/en.

About Medivation
Medivation, Inc. is a biopharmaceutical company focused on the rapid development of novel small molecule drugs to treat serious diseases for which there are limited treatment options. Medivation aims to transform the treatment of these diseases and offer hope to critically ill patients and their families. For more information, please visit us at www.medivation.com.

About the Astellas/Medivation Collaboration
In October 2009, Medivation and Astellas entered into a global agreement to jointly develop and commercialize enzalutamide. The companies are collaborating on a comprehensive development program that includes studies to develop enzalutamide across the full spectrum of advanced prostate cancer as well as advanced breast cancer. The companies jointly commercialize XTANDI in the United States and Astellas will have responsibility for manufacturing and all additional regulatory filings globally, as well as commercializing XTANDI outside the United States.

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SOURCE Astellas Pharma US, Inc.