Discovered by XenoPort, XP21279 is a patented new chemical entity that utilizes naturally-occurring, high-capacity nutrient transporters in the gastrointestinal tract to generate active, efficient absorption into the body. Once absorbed, XP21279 is rapidly converted into L-Dopa, a drug that acts to replace dopamine in the brain. XenoPort currently holds all rights to this product candidate.

Parkinson’s Disease

XP21279 is being developed as a potential treatment for Parkinson's disease. Parkinson’s disease is a motor system disorder that results from the loss of dopamine-producing nerve cells in the brain. Dopamine is a chemical that is naturally produced by the body. It is responsible for smooth, coordinated function of the body’s muscles and movement. When approximately 80% of dopamine-producing cells are damaged, the symptoms of Parkinson’s disease appear. The primary symptoms of Parkinson’s disease are tremor or shaking, slowness of movement, rigidity or stiffness and difficulty with balance. L-Dopa is an immediate precursor of dopamine that, unlike dopamine, readily crosses the blood brain barrier. When administered in conjunction with carbidopa (and, in some cases, with benzerazide or carbidopa and entacapone), L-Dopa is protected from rapid degradation by enzymes that are outside of the brain and is able to be converted to dopamine at its desired site of action in the brain. L-Dopa is widely viewed as one of the most effective treatments of Parkinson’s disease, and virtually all patients with Parkinson’s disease ultimately require it. However, L-Dopa has many undesirable pharmacokinetic characteristics, including its rapid breakdown by gastric and other peripheral enzymes, a short duration in blood after oral dosing that leads to the fluctuation of drug plasma concentrations upon frequent dosing and a narrow absorption window within the gastrointestinal tract. The poor colonic absorption of L-Dopa has precluded the development of a satisfactory sustained-release formulation of L-Dopa that would prolong absorption beyond the small intestine. The pharmacokinetic profile of L-Dopa in the blood after administration of XP21279 shows more constant exposure to L-Dopa and less severe peaks and troughs of drug blood levels than orally administered L-Dopa. As such, we believe the use of XP21279 for the treatment of Parkinson’s disease could provide more continuous exposure to L-Dopa and thereby potentially offer better treatment benefit. We believe that XP21279 has the potential to improve upon the limitations of L-Dopa.