GSK1838262 did not demonstrate a statistically significant improvement on the primary endpoint when compared to placebo, based on the change from baseline to end of treatment on the pain intensity-numerical rating scale (PI-NRS).
The pregabalin active control arm also did not differentiate from placebo on this same endpoint. The failure of the study to demonstrate a statistically significant benefit on the primary endpoint may be a consequence of the unexpectedly high placebo response rate observed in the study.
This 14-week, double-blind, placebo-controlled study enrolled 421 patients who were diagnosed with either type 1 or type 2 diabetes mellitus with signs and symptoms of diabetic peripheral neuropathy (DPN).
Patients were randomized to receive either 1200mg/day, 2400mg/day or 3600mg/day of GSK1838262 administered in divided doses twice daily, 300mg/day of pregabalin as an active control, administered in divided doses three times daily, or placebo. Throughout the study, GSK1838262 was generally well tolerated.
Ronald Barrett, CEO of XenoPort, said: “The failure of pregabalin in this study makes it difficult to draw definitive conclusions about the efficacy of GSK1838262. We are encouraged by the observation that all doses of GSK1838262 were generally well tolerated, particularly since the 3600mg dose represents the highest dose tested in a study of this length.”