October 20, 2020

Cenobamate (Xcopri): Can Preclinical and Clinical Evidence Provide Insight Into Its Mechanism of Action?

Abstract, originally published in Epilepsia

Approximately one-third of people living with epilepsy are unable to obtain seizure control with the currently marketed antiseizure medications (ASMs), creating a need for novel therapeutics with new mechanisms of action. Cenobamate (CBM) is a tetrazole alkyl carbamate derivative that received US Food and Drug Administration approval in 2019 for the treatment of adult partial onset (focal) seizures. Although CBM displayed impressive seizure reduction in clinical trials across all seizure types, including focal aware motor, focal impaired awareness, and focal to bilateral tonic-clonic seizures, the precise mechanism(s) through which CBM exerts its broad-spectrum antiseizure effects is not known. Experimental evidence suggests that CBM differentiates itself from other ASMs in that it appears to possess dual modes of action (MOAs); that is, it predominately blocks persistent sodium currents and increases both phasic and tonic γ-aminobutyric acid (GABA) inhibition.

In this review, we analyze the preclinical efficacy of CBM alongside ASMs with similar MOAs to better understand the mechanism(s) through which CBM achieves such broad-spectrum seizure protection. CBM’s preclinical performance in tests, including the mouse 6-Hz model of treatment-resistant seizures, the chemoconvulsant seizure models of generalized epilepsy, and the rat hippocampal kindling model of focal epilepsy, was distinct from other voltage-gated sodium channel blockers and GABAA¬†modulators. This distinction, in light of its proposed mechanism(s) of action, provides insight into the impressive clinical efficacy of CBM in the adult patient with focal onset epilepsy. The results of this comparative reverse translational analysis suggest that CBM is a mechanistically distinct ASM that offers an important advancement in drug development for treatment of therapy-resistant epilepsy.