Vistagen's AV-101 Drug Candidate Yields Positive Preclinical Data for Neuropathic Pain Applications.

IND to Be Submitted to FDA in 2007

BURLINGAME, Calif. -- VistaGen Therapeutics, Inc., an emerging biopharmaceutical company, focused on stem cell technologies, to discover, develop and commercialize novel small molecule drugs and protein therapeutics for neurological disorders and diabetes, announced positive results from preclinical studies of AV-101, its lead drug candidate, in acute and chronic neuropathic pain animal models.

The preclinical studies suggest that AV-101, a first-in-class prodrug, has the potential to treat pain caused by nerve damage associated with diabetes, viral infections, injuries, and cancer.

"The results of these studies open another significant therapeutic opportunity for our lead compound," said H. Ralph Snodgrass, Ph.D., VistaGen's President and Chief Executive Officer. "We believe AV-101's ability to reduce and control seizures and chronic neuropathic pain is similar to that of gabapentin (Pfizer's Neurontin[R]), the blockbuster drug for epilepsy and neuropathic pain, and due to the lack of side effects, we expect AV-101 to have a higher therapeutic index."

"In our preclinical studies, the relative analgesic dose effects and side-effect profiles of AV-101 were comparable to those of gabapentin," said Tony L. Yaksh, Ph.D, Professor of Pharmacology, School of Medicine, Department of Anesthesiology, University of California, San Diego, and a collaborator with VistaGen on this project. "It was notable that AV-101 had no sedative or motor effects even at the highest doses," added Dr. Yaksh.

The studies were supported by the National Institute of Drug Abuse, a division of the U.S. National Institutes of Health (NIH). The NIH has continued to support VistaGen with over $4 million of nondilutive grant funding for preclinical development of AV-101. VistaGen expects to submit an Investigational New Drug Application, or IND, to the FDA in 2007 and begin clinical development of AV-101 for epilepsy and neuropathic pain in 2008.

Chronic neuropathic pain is a major disorder affecting millions of people worldwide. The neuropathic market is projected to be greater than $4 billion in 2007. Opiates are commonly prescribed widely for neuropathic pain, but are only partially effective, have unwanted side effects, and are prone to substance abuse that limits their use. By contrast, AV-101 is a prodrug with a unique method of action enabling it to penetrate the blood-brain barrier where it is converted selectively at the site of injury in the brain and spinal cord into one of the most potent and specific antagonists of the glycine site of the NMDA receptor. NMDA receptor signaling is thought to be an important mechanism involved in the neurological changes that lead to epilepsy and chronic neuropathic pain. AV-101 is orally active and is expected to have fewer negative side effects than currently available therapies.

About VistaGen Therapeutics

VistaGen Therapeutics, Inc. is a platform-enabled biopharmaceutical company pioneering the use of embryonic stem cells ("ES Cells") as proprietary biological systems for drug discovery and development. VistaGen's core technology is an ES Cell-based R&D platform that could offer a renewable source of breakthrough drug therapies for a wide variety of diseases, including cardiovascular disease, diabetes and multiple neurological disorders such as Parkinson's disease. VistaGen's customized ES Cell-based biological assays and screening systems help discover, validate, and prioritize novel drug targets, as well as identify the biological function and potential therapeutic utility of new drug candidates with greater flexibility, speed and efficiency compared to traditional techniques currently used in the pharmaceutical industry.