TOKYO, JAPAN and SANTA CLARA, CA - January 17, 2012 - Astellas Pharma Inc. (Tokyo: 4503) and XenoPort, Inc. (NASDAQ: XNPT) announced today that Regnite® (gabapentin enacarbil) has received marketing approval in Japan for the treatment of moderate-to-severe primary restless legs syndrome (RLS).

Ronald W. Barrett, Ph.D., chief executive officer of XenoPort, stated, “We are very pleased that Regnite has been approved in Japan. We believe that Regnite can offer treatment benefits to RLS patients whose condition is severe enough to need medical treatment. We thank Astellas for all of its efforts to make Regnite available to RLS patients in Japan.”

The New Drug Application (NDA) filing for Regnite employed a bridging strategy based on data supporting safety and efficacy from the successful Phase 2 study in RLS patients and long-term safety study conducted by Astellas in Japan, as well as the RLS clinical program conducted by XenoPort in the United States and supporting pharmacokinetic studies conducted by XenoPort in Japanese subjects. Each of the efficacy studies showed that treatment with Regnite was associated with improvement in the International Restless Legs Syndrome rating scale score compared to placebo. Improvement over placebo was also observed on the investigator-rated clinical global impression of improvement scale. The most commonly reported adverse events for Regnite were somnolence and dizziness, which were generally transient and mild to moderate in severity. 

Yoshihiko Hatanaka, president & chief executive officer of Astellas, said, “Astellas expects to provide an additional option for RLS therapy by introducing Regnite, which has a different type of mechanism of action than the existing therapy for RLS in Japan.”

About Regnite
Discovered by XenoPort, Regniteonce-daily and delivers a new chemical entity that utilizes naturally-occurring, high-capacity nutrient transporters in the gastrointestinal tract to achieve efficient absorption into the body. Once absorbed, RegniteRegnite provides dose-proportional and extended exposure of gabapentin. is rapidly converted into gabapentin, a compound thought to work by binding to certain calcium channels in the central and peripheral nervous system. (gabapentin enacarbil) is dosed

About Restless Legs Syndrome
Restless legs syndrome is a neurological condition that is characterized by unpleasant and sometimes painful sensations in the legs that result in a compelling urge to move and can result in distressing symptoms that disrupt sleep and significantly impact daily activities. These restless legs syndrome-related symptoms typically begin or worsen during periods of rest or inactivity, particularly when lying down or sitting, and may be temporarily relieved by movement. It is estimated that approximately 2.1 million people in Japan suffer from RLS.

Astellas/XenoPort Collaboration Arrangement
In 2005, Astellas obtained exclusive rights to develop and commercialize Regnitenet sales of Regnitein the Astellas territory at a royalty rate in the mid-teens on a percentage basis.in Japan, Korea, the Philippines, Indonesia, Thailand and Taiwan. XenoPort has received payments of $55 million to date under the collaboration agreement. The approval of Regnitein Japan entitlesXenoPort to an additional milestone payment of $10 million. XenoPort is eligible to receive potential additional clinical and regulatory milestone payments totaling up to $20 million. Under the agreement, XenoPort is also eligible to receive royalties on