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Phase 2 Trial Initiated for Tezampanel, an AMPA/Kainate Receptor Antagonist to Treat Migraine
The double-blind, placebo-controlled, parallel-group study will enroll approximately 300 patients and treat a single migraine attack, with or without aura. Equal numbers of patients will be randomized to one of four arms and receive a 40 mg, 70 mg, or 100 mg single subcutaneous dose of tezampanel or placebo. The primary efficacy endpoint is headache pain relief at two hours post-dose. Secondary efficacy endpoints include pain free at two hours, sustained pain relief and sustained pain free at 24 hours, and headache recurrence and relapse. Additional measures include assessments of functional disability and patient satisfaction, relief of migraine-associated symptoms such as nausea, vomiting, photophobia (sensitivity to light) and phonophobia (sensitivity to sound), as well as various assessments that characterize speed of onset. Safety, tolerability and pharmacokinetics will also be evaluated. The study will be conducted in approximately 25 centers in the U.S.
"The initiation of our Phase IIb trial with tezampanel is an important milestone for TorreyPines and a promising development for the millions of people who suffer with acute migraine," said Neil Kurtz, M.D., President and Chief Executive Officer of TorreyPines. "We believe that tezampanel will not only relieve the acute pain associated with migraine, but also address the underlying mechanisms that precipitate the migraine. Tezampanel has the potential to offer an important new mechanism of action to the treatment of migraine."
In previous clinical trials, tezampanel has been administered to more than 200 healthy adult volunteers or patients. In five Phase IIa, placebo-controlled trials, tezampanel demonstrated proof of concept in multiple pain models. In a placebo and active-controlled trial in patients with acute migraine, the compound, administered intravenously, achieved statistical significance in all primary and secondary endpoints traditionally required for regulatory approval. These endpoints included pain relief at two hours, pain-free at two hours and relief of nausea, photophobia and phonophobia.
TorreyPines' follow-on compound, NGX426, is an oral prodrug of tezampanel and is in Phase I testing. Both compounds may effectively relieve severe and persistent pain through a novel mechanism that may not impart the side effects and risks associated with currently available migraine and other chronic pain treatments.
About AK Receptor Antagonists
AK receptor antagonists selectively block transmission of pain signals mediated through the activation of a subtype of glutamate receptors. These receptors play a critical role in the development of central sensitization phenomena -- a key component of many pain syndromes, including migraine and persistent pain states such as chronic neuropathic pain. Because they do not block opioid receptors, constrict blood vessels or interact with systems external to the central nervous system at dosages that are therapeutically relevant, the safety profile of AK antagonists may offer important advantages over existing drugs.
Migraine is a painful neurological condition characterized by an intense and disabling episodic headache. According to the National Headache Foundation, an estimated 30 million people in the U.S. suffer from migraines. Approximately 25 percent of migraine sufferers endure at least one attack per week. In addition to headache pain, migraine attacks are frequently accompanied by sensitivity to light (photophobia) and sound (phonophobia), nausea and vomiting. Although once thought to be primarily caused by vascular changes in the brain, researchers now consider migraine a neurological disorder. In the U.S., the prescription migraine market is approximately $2 billion, with the market leader, Imitrex(R), accounting for approximately half of all sales.
Source: TorreyPines Therapeutics