XenoPort (XNPT)) Announces Plans for Phase 3 Development of Arbaclofen Placarbil for Spasticity

SANTA CLARA, Calif., Sep 13, 2010 (BUSINESS WIRE) — XenoPort, Inc. /quotes/comstock/15*!xnpt/quotes/nls/xnpt (XNPT 7.55, +1.35, +21.77%) announced today that it plans to move arbaclofen placarbil (AP), also known as XP19986, into Phase 3 development as a potential treatment of spasticity in multiple sclerosis (MS) patients. Following discussions with the U.S. Food and Drug Administration (FDA), XenoPort intends to conduct a single placebo-controlled Phase 3 efficacy clinical trial and an open-label, long-term, safety study of AP in patients with MS. Favorable results from these studies could lead to the filing of a new drug application (NDA) with the FDA under Section 505(b)(2) seeking approval of AP for the treatment of spasticity.

Ronald W. Barrett, chief executive officer of XenoPort, stated, “In our previous Phase 2 clinical trial in spinal cord injury patients with spasticity, AP was well tolerated and demonstrated dose-dependent improvement in muscle tone that was maintained throughout the twelve-hour dosing interval. We hope to demonstrate similar results in our Phase 3 trial of AP in MS patients with spasticity.”

Randall Schapiro, M.D., Clinical Professor of Neurology at the University of Minnesota and President of the Schapiro Multiple Sclerosis Advisory Group, stated, “Available treatments do not fully address the needs of MS patients with spasticity. Baclofen is often used in these patients, but its short duration of action and central nervous system side effects can result in sub-optimal therapy. A new oral medicine that could maintain efficacy with limited adverse events would be a welcome addition to the spasticity treatment armamentarium.”

XenoPort intends to initiate this Phase 3 clinical program in the first half of 2011. The pivotal trial would be a multi-center, randomized, double-blind, placebo-controlled study designed to assess the efficacy and safety of AP as a treatment for spasticity in MS patients. Patients who complete this study would have the option to enter a long-term study to evaluate the safety of AP in MS patients. Following successful outcomes from these studies, XenoPort would file an NDA with the FDA using the 505(b)(2) application process. The 505(b)(2) application would enable XenoPort to reference published literature and the FDA’s previous finding of safety and effectiveness for baclofen, a drug that has been approved by the FDA for the alleviation of signs and symptoms of spasticity resulting from MS.

About Arbaclofen Placarbil (AP)

AP is a patented new chemical entity that is a Transported Prodrug of R-baclofen designed to engage natural nutrient transport mechanisms found on intestinal cell membranes, thereby gaining efficient entrance into the bloodstream. AP is then rapidly converted by high-capacity enzymes to the parent compound and natural substances with favorable safety characteristics. R-baclofen is an agonist of the target known as gamma amino-butyric acid(B), or GABA(B), receptor. Baclofen, which is a mixture of the R- and S-isomers, is an approved treatment for spasticity that is administered three or four times a day.

XenoPort has completed a successful Phase 2 clinical trial of AP in patients with spasticity due to spinal cord injury. AP treatment was associated with statistically significant differences from placebo at all time points in the 20 mg and 30 mg twice-a-day AP dose cohorts. AP was well tolerated at all dose levels.

About Spasticity

Spasticity is a debilitating condition that is associated with some common neurological disorders, such as MS, stroke and cerebral palsy, as well as spinal cord injury. The underlying cause of spasticity is unknown, but it is believed to result from an imbalance of inhibitory and excitatory functioning within the central nervous system. Patients with spasticity may experience abnormal increases in muscle tone that are associated with loss of range of motion, increased muscle stretch reflexes, weakness and problems with coordination. Common complications of spasticity include joint and muscle contracture, pain and difficulty performing activities of daily living.

According to “We Move”, a non-profit organization providing patient information and continuing medical education to professionals, two out of every 1,000 people in North America suffer from MS and roughly 200,000 people in the United States suffer from spinal cord injury. It is estimated that spasticity affects between 37% and 78% of MS patients and 40% of spinal cord injury patients.

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 collaborating with Astellas Pharma Inc. and GlaxoSmithKline to develop and commercialize XP13512, its lead product candidate. XenoPort’s product candidates are being studied for the potential treatment of restless legs syndrome, gastroesophageal reflux disease, neuropathic pain, spasticity 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 the potential of AP as a treatment of spasticity in MS patients; XenoPort’s planned AP clinical development program and the timing and the results thereof; planned clinical trial designs; the potential for the filing of an NDA with the FDA under Section 505(b)(2); and the suitability of AP as a treatment for spasticity. 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,” “could,” “expects,” “hope,” “intends,” “may,” “planning,” “plans,” “potential,” “would” 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, the uncertain results and timing of clinical trials; XenoPort’s ability to successfully conduct clinical trials in the anticipated timeframes, or at all; the uncertainty of the FDA’s regulatory process, including uncertainty as to whether the FDA would approve an NDA filed under Section 505(b)(2); XenoPort’s dependence on its current and additional collaborative partners; and the therapeutic and commercial value of XenoPort’s product candidates. These and other risk factors are discussed under the heading “Risk Factors” in XenoPort’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2010, filed with the Securities and Exchange Commission on August 6, 2010. 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.

XenoPort and Transported Prodrug are trademarks of XenoPort, Inc.