XenoPort announced it has initiated a Phase 2b clinical trial of arbaclofen placarbil, also known as XP19986, in patients with gastroesophageal reflux disease (GERD) who remain symptomatic despite treatment with a proton pump inhibitor (PPI). This trial is a multi-center, randomized, double-blind, placebo-controlled study designed to assess the efficacy and safety of AP as adjunctive therapy to PPIs. XenoPort expects to enroll approximately 425 subjects in this trial, which is being conducted in the United States and Canada. Subjects with a history of incomplete response to a PPI will undergo a four-week run-in on PPI therapy followed by a six-week treatment period on PPI therapy plus either 20 mg or 40 mg of AP dosed once daily, 20 mg or 30 mg of AP dosed twice daily or placebo. The primary endpoint of the study will examine heartburn events. Regurgitation will be assessed as a key secondary endpoint.

AP (arbaclofen placarbil) is a Transported Prodrug of R-baclofen that is 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 R-baclofen and natural substances that have well-studied, favorable safety characteristics. R-baclofen is an agonist of a target known as the gamma amino-butyric acid(B), or GABA(B), receptor. Racemic baclofen (a mixture of R and S isomers) has been approved for the treatment of spasticity and has been shown in clinical studies to have efficacy in a number of other therapeutic indications, including GERD.

For more information call (408) 616-7200 or visit www.XenoPort.com.