XenoPort Announces Positive Phase 2 Study Results for XP23829 as a Potential Treatment for Patients with Psoriasis

XenoPort, Inc. (Nasdaq: XNPT) announced today positive preliminary top-line results from its Phase 2 clinical trial of XP23829 as a potential treatment for moderate-to-severe chronic plaque-type psoriasis. XP23829 met its primary endpoint in both 800 mg once daily and 400 mg twice daily doses, demonstrating statistically significant improvements in percent change from baseline to week 12 in Psoriasis Area and Severity Index (PASI) score. XP23829 is a patented prodrug of monomethyl fumarate (MMF) in a novel oral formulation that was designed to potentially offer physicians and patients an effective, better tolerated and easier to use therapeutic option to currently available fumarate products. Richard Kim, M.D., chief medical officer of XenoPort, stated, "We believe these clinical data demonstrate for the first time that a MMF prodrug other than dimethyl fumarate (DMF) can be effective in reducing lesions in psoriatic patients. The magnitude of XP23829's effect on the primary efficacy endpoint met our expectations for this relatively short duration trial and we are particularly encouraged by the results with 800 mg once-daily dosing. Based on what is known about fumarates, we believe that the efficacy of XP23829 is likely to improve with a more extended duration of treatment beyond 12 weeks. We are also pleased with the safety and tolerability profile of XP23829 emerging from this study. We believe that this demonstration of efficacy, safety and tolerability of XP23829 could lead to a differentiated product in psoriasis. We also believe that there is potential for the observations from this study to read through to other potential indications such as multiple sclerosis (MS)." Description of the Trial This randomized, double-blind, placebo-controlled Phase 2 clinical trial of XP23829 was conducted in 33 sites in the United States in subjects with moderate-to-severe chronic plaque-type psoriasis. Two hundred eligible subjects were randomized to placebo or one of three treatment arms of XP23829: 400 mg or 800 mg once daily (QD) or 400 mg twice daily (BID). The 12-week treatment period included a three-week titration period followed by nine weeks of treatment at the targeted dose. There was a washout phase of up to four weeks prior to randomization for subjects who were previously taking systemic agents for the treatment of psoriasis. Treatment assignment was stratified based on prior biologic use and approximately 35% of randomized subjects had previous experience with biological treatments for their psoriasis. The primary endpoint of the study was the percent change from baseline to week 12 in PASI score. Least squares mean percent reductions in PASI score at 12 weeks were as follows: 400 mg QD 800 mg QD 400 mg BID Placebo Least squares mean -38.1 -48.2 -50.7 -25.0 p-value 0.066 0.001