Testing the effects of a selective calpain-2 inhibitor on spontaneous recurrent seizures in mouse models of epilepsy

Abstract
Epilepsy is the most prevalent neurological diseases after migraines. Current antiepileptic drug treatments
mainly attempt to reduce excitation or enhance inhibition in order to control seizures. Unfortunately, such
therapeutics result in a number of undesirable side-effects, and demonstrate limited efficacy against drug-
resistant cases of epilepsy. So far, no treatment has been developed as an anti-epileptogenic agent, in part
because of the limited understanding of the processes involved in the development of epilepsy. It is generally
accepted that up to 50% of all epileptic patients become epileptic as a result of a triggering initial injury such as
status epilepticus, stroke or traumatic brain injury. This initial triggering injury has been postulated to activate a
cascade of events leading to further seizures, increased brain damage and self-propagation. Calpains are a
family of soluble calcium-dependent proteases, which have been implicated in epilepsy, since they are activated
by seizures and participate in neuronal damage. Recent studies have also indicated that during early
epileptogenesis, seizure occurrence, calpain activity and neuronal damage are correlated, and that treatment
with a non-selective calpain inhibitor reduces the development of spontaneous recurrent seizures (SRS) in the
pilocarpine model of epilepsy in rats. Our laboratory has demonstrated that calpain-1 and calpain-2, two of the
major calpain isoforms in the brain, have opposite functions in the brain. We have also found that calpain-2
conditional knock-out mice with calpain-2 deletion in excitatory neurons from the forebrain show normal seizure
activity following injections of repeated low doses of kainic acid (KA) but exhibit no brain inflammation,
degeneration and cognitive impairment in hippocampus-dependent learning 7 days after seizures. Similar
protective results were obtained when wild-type mice were treated daily and for seven days after seizures with
a selective calpain-2 inhibitor. These results strongly support the hypothesis that calpain-2 might represent a
potential therapeutic target to prevent various pathological consequences of seizures. This Phase I STTR is
directed at first determining whether a selective calpain-2 inhibitor, NA-184, might prevent the appearance of
SRSs or reduce their frequency in two mouse models of epilepsy, the repeated low doses of kainic acid (KA) or
of pilocarpine models (Aim #1). In Aim # 2, we will test the effects of intranasal administration of NA-184 on KA-
and pilocarpine-induced neuropathology, as intranasal delivery of a variety of anti-epileptic drugs is increasingly
used in the clinic. In Phase II of this STTR, we will further pursue the development of intranasal delivery of NA-
184 as an anti-epileptic treatment. NeurAegis is a small biotech company focusing on the development of
selective calpain-2 inhibitors for the treatment of acute neuronal injury, including traumatic brain injury and
repeated concussions. This proposal is directed at expanding the potential applications of these calpain-2
inhibitors by determining whether they could also be developed as potential therapeutic treatment for epilepsy.

Grant Number: 5R41NS130825-02
NIH Institute/Center: NIH
Principal Investigator: MICHEL BAUDRY