XenoPort Announces Astellas' Plans to File an NDA for XP13512 in Japan

XenoPort Announces Astellas' Plans to File an NDA for XP13512 in Japan

SANTA CLARA, Calif.--(BUSINESS WIRE)--Aug 3, 2009 - XenoPort, Inc. (Nasdaq:XNPT) announced today that Astellas Pharma Inc. plans to file a new drug application (NDA) in Japan forXP13512 (known as ASP8825 by Astellas) as a potential treatment for moderate-to-severe primary restless legs syndrome (RLS) in the second half of its 2009 fiscal year, which ends on March 31, 2010. The evidence of efficacy for the NDA filing will be based on data from Astellas' successful Phase 2 study in RLS patients conducted in Japan and XenoPort's clinical program conducted in the United States. Based on the outcome of a Pharmaceutical and Medical Devices Agency (PMDA) consultation meeting, Astellas has concluded that Phase 3 clinical studies in Japan will not be required for the NDA filing.

"With no approved drugs in Japan for the treatment of RLS, we are pleased that Astellas is pursuing what is known as a "bridging strategy" to potentially accelerate the availability of a treatment for RLS patients in Japan," said Ronald W. Barrett, Ph.D., XenoPort's chief executive officer. "We are working diligently with Astellas to permit them to move aggressively to file the NDA in Japan by the end of March 2010. We thank our Astellas colleagues for their creative development strategy on this project."

XenoPort also announced today that Astellas does not intend to continue the development of XP13512 in Japan as a potential treatment for painful diabetic neuropathy under the current circumstances. As reported previously, a planned interim analysis of a Phase 2 clinical trial of XP13512 in Japanese patients with painful diabetic neuropathy indicated that continuation of the study was not likely to demonstrate a statistically significant advantage of XP13512 over placebo on the primary endpoint of the study. There were no safety concerns identified in the interim analysis.

Astellas Collaboration

Astellas holds exclusive rights to develop and commercialize XP13512 in Japan, Korea, the Philippines, Indonesia, Thailand and Taiwan. Under the terms of the Astellas collaboration agreement, XenoPort received an initial license payment of $25 million in December 2005 and has received milestone payments of $18 million to date. XenoPort is eligible to receive potential clinical and regulatory milestone payments totaling up to an additional $42 million. In addition, assuming regulatory approval, XenoPort is entitled to receive royalties on any sales of XP13512 in the Astellas territory.

About XP13512

XP13512 is a new chemical entity that is designed to improve upon the pharmacokinetics of gabapentin by taking advantage of high-capacity transport mechanisms in the gastrointestinal tract to improve absorption.

About XenoPort

XenoPort, Inc. is a biopharmaceutical company focused on developing a portfolio of internally discovered product candidates that utilize the body's natural nutrient transport mechanisms to improve the therapeutic benefits of existing drugs. XenoPort is developing its lead product candidate, XP13512, in collaboration with Astellas and GlaxoSmithKline (GSK). The Food and Drug Administration is currently reviewing GSK's NDA for XP13512 as a potential treatment for moderate-to-severe primary RLS in the United States. XenoPort's product candidates are also being studied for the potential treatment of gastroesophageal reflux disease, migraine headaches, neuropathic pain, spasticity related to spinal cord injury, acute back spasms and Parkinson's disease.

To learn more about XenoPort, please visit the Web site at www.XenoPort.com.

Forward-Looking Statements

This press release contains "forward-looking" statements, including, without limitation, all statements related to XenoPort's and its partners' future clinical development and commercialization of XP13512 and the timing thereof; the therapeutic and commercial potential of XP13512; the suitability of XP13512 as a treatment for RLS; the regulatory process and the timing thereof; and potential royalty and milestone payments and the timing thereof. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "believe," "intend," "plans," "potential," "will" and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon XenoPort's current expectations. Forward-looking statements involve risks and uncertainties. XenoPort's actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks related to the uncertainty of the FDA approval process, the PMDA NDA filing process and other regulatory requirements; XenoPort's dependence on its current collaborative partners; and the uncertain therapeutic and commercial value of XP13512. These and other risk factors are discussed under the heading "Risk Factors" in XenoPort's prospectus supplement filed with the Securities and Exchange Commission under Rule 424(b)(5) on July 8, 2009. XenoPort expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in the company's expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.