GlaxoSmithKline (GSK) and partner XenoPort Inc. (XNPT) suffered a pipeline setback recently when Horizant (GSK1838262/XP13512) failed to achieve its primary endpoint in a phase IIb study.
 
Results from a 30-week, double-blind, placebo-controlled study showed that Horizant did not achieve a statistically significant improvement in preventing migraine headaches compared to placebo. Glaxo and XenoPort said that the failure in achieving statistical significance could be due to the high response rate seen in the placebo arm.
 
The study, involving 526 patients, was being conducted to evaluate the efficacy, safety and tolerability of Horizant. Four doses (1200, 1800, 2400 or 3000 mg) of Horizant were used in the study.
 
In addition to failing to achieve the primary endpoint, two patients in the Horizant arm died. While one death was due to bronchopneumonia and was unrelated to Horizant, the other death was due to an accidental overdose of medications apart from Horizant. The companies said that the relationship to Horizant could not be established in the second death.
 
The study results are a major disappointment for both Glaxo and XenoPort. In fact, this is the second Horizant-related setback received by the companies in 2010. Earlier this year, in February, the US Food and Drug Administration (FDA) issued a complete response letter to Glaxo and XenoPort for their new drug application (NDA) seeking approval for the use of Horizant for the treatment of restless legs syndrome.
 
While Glaxo and XenoPort said that they are committed to bringing Horizant to the market, chances are that Glaxo could opt out of its collaboration agreement with XenoPort.
 
We note that Glaxo recently announced that it intends to stop pursuing research activity in certain areas including depression and pain. The company instead intends to focus its research activities in higher growth areas like neurodegenerative and neuro-inflammatory diseases like Alzheimer’s disease, multiple sclerosis and Parkinson’s disease. Glaxo’s withdrawal from the collaboration would be a major setback for XenoPort.
 
We currently have a Neutral recommendation on both Glaxo (Zacks Rank #3 – Hold) and XenoPort (Zacks Rank #3 – Hold).
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