Tokyo, Japan– March 24, 2014 – Astellas Pharma Inc. (TSE: 4503) today announced that Astellas has obtained the marketing approval of oral androgen receptor signaling inhibitor, XTANDI® capsules 40mg (development code: MDV3100; generic name: enzalutamide) for the treatment of patients with castration-resistant prostate cancer in Japan. Astellas filed an application for approval in Japan in May 2013. 

XTANDI is a once-daily, oral androgen receptor signaling inhibitor. It inhibits multiple steps in the androgen receptor signaling pathway, which has been shown to decrease cancer cell growth and can induce cancer cell death (apoptosis).

XTANDI (product name in Europe and the US: XTANDI®), which is being jointly developed and commercialized with US-based company, Medivation Inc. (NASDAQ MDVN), obtained approval in August 2012 in the U.S. and in June 2013 in Europe for the treatment of metastatic castration-resistant prostate cancer (mCRPC) in patients who have previously received docetaxel (chemotherapy).

Upon receiving this marketing authorization in Japan, Astellas will provide Medivation with a $15 million milestone payment.

Summary of Approval

Brand name:       XTANDI® Capsules 40mg

Generic name:    Enzalutamide

Indication:          Castration-resistant prostate cancer

Precautions regarding indication:

1.  The efficacy and safety of the drug have not been established in patients with prostate cancer who have not received chemotherapy.

2. Appropriate patients shall be selected by physicians who are well aware of the details of the “clinical results” and who have sufficient understanding of the efficacy and safety of the drug.

Dosage regimen: Normally, 160mg of enzalutamide is administered orally, once daily.

Precautions regarding dosage regimen:

Efficacy and safety without surgery or medical castration have not been established.

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