Epilepsy is one of the most prevalent neurological disorders, affecting almost 1% of the worldwide population. According to the Epilepsy Foundation, as many as three million Americans have epilepsy, and one-third of those suffering from epilepsy are not effectively treated with currently available medications.1 In addition, standard anticonvulsants can cause significant side effects, which frequently interfere with compliance.
Glutamate is a neurotransmitter that is also critically involved in the pathophysiology of epilepsy. Through its stimulation of the NMDA receptor subtype, glutamate has been implicated in the neuropathology and clinical symptoms of the disease. In support of this, NMDA receptor antagonists are potent anticonvulsants. However, as noted, classic ion channel-blocking NMDA receptor antagonists are limited by adverse effects, such as neurotoxicity, declining mental status, and the onset of psychotic symptoms following administration of the drug. The endogenous amino acid glycine modulates glutamatergic neurotransmission by stimulating the glycine coagonist site of the NMDA receptor. Glycine site antagonists such as AV-101’s active metabolite, 7-Cl-KYNA, inhibit NMDAR function and are therefore anticonvulsant and neuroprotective. Importantly, glycine site antagonists have fewer and less severe side effects than classic ion channel-blocking NMDA receptor antagonists and other antiepileptic agents, making them a safer potential alternative to, and one expected to be associated with greater patient compliance than, currently available anticonvulsant medications.
In addition, another active metabolite of AV-101, 4-Cl-3-hydroxyanthranilic acid, inhibits the synthesis of quinolinic acid (QUIN), which is an endogenous NMDA receptor agonist that causes convulsions and excitotoxic neuronal damage.
AV-101 has been shown to protect against seizures and neuronal damage in preclinical animal models of epilepsy. We believe AV-101’s dual action as a NMDA receptor GlyB antagonist and QUIN synthesis inhibitor, and exploratory preclinical data, together with human safety data in all clinical studies to date, may provide support for AV-101’s potential as a Phase 2a clinical development candidate for treatment of epilepsy.
- Epilepsy Foundation, https://www.epilepsy.com/learn/about-epilepsy-basics/what-epilepsy