FDA approved XenoPort and partner GSK’s Horizant (gabapentin enacarbil) extended release tablets for the management of postherpetic neuralgia (PHN) in adults. Clearance was based on three clinical trials involving 574 patients, including a single 12-week principal efficacy study and two supporting trials. XenoPort will receive a $10 million milestone payment once GSK has made its first commercial sale of the drug.
Originally discovered by XenoPort, Horizant was approved in the U.S. for the treatment of moderate-to-severe primary restless legs syndrome (RLS) in adults during April 2011, and is also approved (tradenamed Regnite®) for the treatment of RLS in Japan. GSK holds commercialization rights and certain development rights to Horizant in the U.S. The drug is XenoPort’s first FDA-approved product, and is being developed in partnership with Astrellas Pharma in Japan and five Asian countries.
XenoPort is developing a pipeline of drugs for neurological disorders including neuropathic pain, spasticity, and Parkinson disease. The firm’s arbaclofen placarbil candidate is in Phase III development for the treatment of spasticity, and the levodopa prodrug XP21279 has completed Phase II studies as a potential treatment for Parkinson disease. Arbaclofen placarbil is a prodrug that is converted in vivo to the R-isomer of the selective GABA-B agonist baclofen.
XenoPort submitted an IND application to FDA last month requesting approval to start clinical trials with its methyl hydrogen fumarate prodrug candidate XP23829, as a potential treatment for relapsing remitting multiple sclerosis.