Efficacy of (S)-lacosamide in preclinical models of cephalic pain

Abstract

Migraine is one of the world's most common neurological disorders. Current acute migraine treatments have suboptimal efficacy, and new therapeutic options are needed. Approaches targeting calcitonin gene related peptide (CGRP) signaling are clinically effective, but small molecule antagonists have not been advanced because of toxicity. In this study, we explored the axonal growth/specification collapsin response mediator protein 2 (CRMP2) as a novel “druggable” target for inhibiting CGRP release and for potential relevance for treatment of migraine pain. Collapsin response mediator protein 2 has been demonstrated to regulate N-type voltage-gated Ca2+ channel activity and Ca2+-dependent CGRP release in sensory neurons. The coexpression of CRMP2 with N-type voltage-gated Ca2+ channel and CGRP in trigeminal ganglia (TGs) sensory neurons suggested the possibility of a novel approach to regulate CGRP release in the trigeminal system. Screening protocols surprisingly revealed that (S)-lacosamide ((S)-LCM), an inactive analog of the clinically approved small molecule antiepileptic drug (R)-lacosamide (Vimpat), inhibited CRMP2 phosphorylation by cyclin-dependent kinase 5 in rat TG slices and decreased depolarization-evoked Ca2+ influx in TG cells in culture. (S)-LCM significantly blocked capsaicin-evoked CGRP release from dural nerve terminals in the rat in ex vivo cranial cup preparation. Additionally, cephalic and extracephalic cutaneous allodynia induced in rats by activation of dural nociceptors with a cocktail of inflammatory mediators, was inhibited by oral administration of (S)-LCM. The confirmation of CRMP2 as an upstream mediator of CGRP release, together with the brain penetrance of this molecule suggests (S)-LCM as a potential therapy for acute migraine.

Phosphorylated CRMP2 Regulates Spinal Nociceptive Neurotransmission

“…Dorsal root ganglion neurons were loaded for 30 minutes at 37°C with 3 μM Fura-2AM (Cat# F1221, Thermo Fisher, stock solution prepared at 1mM in DMSO, 0.02% pluronic acid, Cat#P-3000MP, Life technologies) to follow changes in intracellular calcium([Ca 2+ ] c ) in a standard bath solution containing 139 mM NaCl, 3 mM KCl, 0.8 mM MgCl 2 , 1.8 mM CaCl 2 , 10 mM Na HEPES, pH 7.4, 5 mM glucose exactly as previously described [19,13,[47][48][49]43,45]. Fluorescence imaging was performed with an inverted microscope, NikonEclipseTi-U (Nikon Instruments Inc., Melville, NY), using objective Nikon Fluor 4X and a Photometrics cooled CCD camera Cool SNAP ES 2 (Roper Scientific, Tucson, AZ) controlled by Nis Elements software (version 4.20, Nikon Instruments).…”

Activity of T-type calcium channels is independent of CRMP2 in sensory neurons

“…In chronic pain, proteins regulating the N-type (CaV2.2) VGCCs can modulate nociception [1]. One such protein is the collapsin response mediator protein 2 (CRMP2) [3][4][5][6][7][8][9][10][11][12][13][14][15]. Our continuing studies have established CRMP2 as a bona fide binding partner and regulator of the presynaptic trafficking of CaV2.2 [4,8,13,[15][16][17][18].…”

Evaluation of edonerpic maleate as a CRMP2 inhibitor for pain relief

“…Whole-cell voltage clamp recordings were performed at room temperature (RT) using an EPC 10 Amplifier-HEKA as previously described [6]. The internal solution for voltage clamp sodium current recordings contained (in millimolar): 140 CsF, 1.1 CsEGTA, 10 NaCl, and 15 HEPES (pH 7.3, 290-310 mOsm/L) and external solution contained (in millimolar): 140 NaCl, 3 KCl, 30 tetraethylammonium chloride, 1 CaCl2, 0.5 CdCl2, 1 MgCl2, 10 D-glucose, and 10 HEPES (pH 7.3, 310-315 mosM/L).…”

“…Edonerpic maleate was found to disrupt CRMP2 tetramers [10]. Our previous body of work has established a role for phosphorylated and non-phosphorylated CRMP2 in control of voltage-gated calcium and sodium channels [1,[3][4][5][6][7][8][13][14][15][16][17][18][19][20][21][22]. Therefore, we tested the effect of edonerpic maleate on these channels.…”

“…Actions of CRMP2 are tightly regulated by post-translational modifications [1]. In chronic neuropathic pain, we found that CRMP2 phosphorylation by cyclin-dependent kinase 5 (Cdk5) on Serine 522 (S522) was sufficient for mechanical allodynia [2] through the facilitation of CaV2.2 and NaV1.7 function [4][5][6][7][8]. By contrast, CRMP2 phosphorylation by the src tyrosineprotein kinase Fyn on tyrosine 32 (Y32) inhibits NaV1.7 [4].…”