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BACKGROUND AND PURPOSE: Inhibitors of voltage-gated sodium channels (NaVs) are important anti-epileptic drugs, but the contribution of specific channel isoforms is unknown since available inhibitors are non-selective. We aimed to create novel, isoform selective inhibitors of Nav channels as a means of informing the development of improved antiseizure drugs. EXPERIMENTAL APPROACH: We created a series of compounds with diverse selectivity profiles enabling block of NaV1.6 alone or together with NaV1.2. These novel NaV inhibitors were evaluated for their ability to inhibit electrically evoked seizures in mice with a heterozygous gain-of-function mutation (N1768D/+) in Scn8a (encoding NaV1.6) and in wild-type mice. KEY RESULTS: Pharmacologic inhibition of NaV1.6 in Scn8aN1768D/+ mice prevented seizures evoked by a 6-Hz shock. Inhibitors were also effective in a direct current maximal electroshock seizure assay in wild-type mice. NaV1.6 inhibition correlated with efficacy in both models, even without inhibition of other CNS NaV isoforms. CONCLUSIONS AND IMPLICATIONS: Our data suggest NaV1.6 inhibition is a driver of efficacy for NaV inhibitor anti-seizure medicines. Sparing the NaV1.1 channels of inhibitory interneurons did not compromise efficacy. Selective NaV1.6 inhibitors may provide targeted therapies for human Scn8a developmental and epileptic encephalopathies and improved treatments for idiopathic epilepsies.
RESUMEN
NBI-921352 (formerly XEN901) is a novel sodium channel inhibitor designed to specifically target NaV1.6 channels. Such a molecule provides a precision-medicine approach to target SCN8A-related epilepsy syndromes (SCN8A-RES), where gain-of-function (GoF) mutations lead to excess NaV1.6 sodium current, or other indications where NaV1.6 mediated hyper-excitability contributes to disease (Gardella and Møller, 2019; Johannesen et al., 2019; Veeramah et al., 2012). NBI-921352 is a potent inhibitor of NaV1.6 (IC500.051 µM), with exquisite selectivity over other sodium channel isoforms (selectivity ratios of 756 X for NaV1.1, 134 X for NaV1.2, 276 X for NaV1.7, and >583 Xfor NaV1.3, NaV1.4, and NaV1.5). NBI-921352is a state-dependent inhibitor, preferentially inhibiting inactivatedchannels. The state dependence leads to potent stabilization of inactivation, inhibiting NaV1.6 currents, including resurgent and persistent NaV1.6 currents, while sparing the closed/rested channels. The isoform-selective profile of NBI-921352 led to a robust inhibition of action-potential firing in glutamatergic excitatory pyramidal neurons, while sparing fast-spiking inhibitory interneurons, where NaV1.1 predominates. Oral administration of NBI-921352 prevented electrically induced seizures in a Scn8a GoF mouse,as well as in wild-type mouse and ratseizure models. NBI-921352 was effective in preventing seizures at lower brain and plasma concentrations than commonly prescribed sodium channel inhibitor anti-seizure medicines (ASMs) carbamazepine, phenytoin, and lacosamide. NBI-921352 waswell tolerated at higher multiples of the effective plasma and brain concentrations than those ASMs. NBI-921352 is entering phase II proof-of-concept trials for the treatment of SCN8A-developmental epileptic encephalopathy (SCN8A-DEE) and adult focal-onset seizures.
Asunto(s)
Epilepsia , Canal de Sodio Activado por Voltaje NAV1.6 , Animales , Mutación con Ganancia de Función , Ratones , Mutación , Canal de Sodio Activado por Voltaje NAV1.6/genética , Neuronas/fisiología , Ratas , Sodio , Bloqueadores de los Canales de Sodio/farmacologíaRESUMEN
Nav1.7 is an extensively investigated target for pain with a strong genetic link in humans, yet in spite of this effort, it remains challenging to identify efficacious, selective, and safe inhibitors. Here, we disclose the discovery and preclinical profile of GDC-0276 (1) and GDC-0310 (2), selective Nav1.7 inhibitors that have completed Phase 1 trials. Our initial search focused on close-in analogues to early compound 3. This resulted in the discovery of GDC-0276 (1), which possessed improved metabolic stability and an acceptable overall pharmacokinetics profile. To further derisk the predicted human pharmacokinetics and enable QD dosing, additional optimization of the scaffold was conducted, resulting in the discovery of a novel series of N-benzyl piperidine Nav1.7 inhibitors. Improvement of the metabolic stability by blocking the labile benzylic position led to the discovery of GDC-0310 (2), which possesses improved Nav selectivity and pharmacokinetic profile over 1.
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Azetidinas/farmacología , Benzamidas/farmacología , Descubrimiento de Drogas , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Sulfonamidas/farmacología , Bloqueadores del Canal de Sodio Activado por Voltaje/farmacología , Animales , Azetidinas/química , Azetidinas/farmacocinética , Benzamidas/química , Benzamidas/farmacocinética , Células Cultivadas , Células HEK293 , Humanos , Piperidinas/química , Piperidinas/farmacocinética , Piperidinas/farmacología , Ratas Sprague-Dawley , Sulfonamidas/química , Sulfonamidas/farmacocinética , Bloqueadores del Canal de Sodio Activado por Voltaje/química , Bloqueadores del Canal de Sodio Activado por Voltaje/farmacocinéticaRESUMEN
Nonselective antagonists of voltage-gated sodium (NaV) channels have been long used for the treatment of epilepsies. The efficacy of these drugs is thought to be due to the block of sodium channels on excitatory neurons, primarily NaV1.6 and NaV1.2. However, these currently marketed drugs require high drug exposure and suffer from narrow therapeutic indices. Selective inhibition of NaV1.6, while sparing NaV1.1, is anticipated to provide a more effective and better tolerated treatment for epilepsies. In addition, block of NaV1.2 may complement the anticonvulsant activity of NaV1.6 inhibition. We discovered a novel series of aryl sulfonamides as CNS-penetrant, isoform-selective NaV1.6 inhibitors, which also displayed potent block of NaV1.2. Optimization focused on increasing selectivity over NaV1.1, improving metabolic stability, reducing active efflux, and addressing a pregnane X-receptor liability. We obtained compounds 30-32, which produced potent anticonvulsant activity in mouse seizure models, including a direct current maximal electroshock seizure assay.
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Amidas/química , Sistema Nervioso Central/metabolismo , Epilepsia/tratamiento farmacológico , Canal de Sodio Activado por Voltaje NAV1.6/metabolismo , Bloqueadores de los Canales de Sodio/metabolismo , Bloqueadores de los Canales de Sodio/farmacología , Animales , Perros , Células Hep G2 , Humanos , Células de Riñón Canino Madin Darby , Ratones , Modelos Moleculares , Canal de Sodio Activado por Voltaje NAV1.6/química , Dominios Proteicos , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Bloqueadores de los Canales de Sodio/química , Bloqueadores de los Canales de Sodio/uso terapéutico , Relación Estructura-ActividadRESUMEN
Herein, we report the discovery and optimization of a series of orally bioavailable acyl sulfonamide NaV1.7 inhibitors that are selective for NaV1.7 over NaV1.5 and highly efficacious in in vivo models of pain and hNaV1.7 target engagement. An analysis of the physicochemical properties of literature NaV1.7 inhibitors suggested that acyl sulfonamides with high fsp3 could overcome some of the pharmacokinetic (PK) and efficacy challenges seen with existing series. Parallel library syntheses lead to the identification of analogue 7, which exhibited moderate potency against NaV1.7 and an acceptable PK profile in rodents, but relatively poor stability in human liver microsomes. Further, design strategy then focused on the optimization of potency against hNaV1.7 and improvement of human metabolic stability, utilizing induced fit docking in our previously disclosed X-ray cocrystal of the NaV1.7 voltage sensing domain. These investigations culminated in the discovery of tool compound 33, one of the most potent and efficacious NaV1.7 inhibitors reported to date.
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Analgésicos/química , Canal de Sodio Activado por Voltaje NAV1.7/química , Sulfonamidas/química , Bloqueadores del Canal de Sodio Activado por Voltaje/química , Analgésicos/metabolismo , Analgésicos/uso terapéutico , Animales , Sitios de Unión , Diseño de Fármacos , Semivida , Humanos , Masculino , Ratones , Ratones Transgénicos , Microsomas Hepáticos/metabolismo , Simulación del Acoplamiento Molecular , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Dolor/inducido químicamente , Dolor/tratamiento farmacológico , Dolor/patología , Estructura Terciaria de Proteína , Ratas , Ratas Sprague-Dawley , Relación Estructura-Actividad , Sulfonamidas/metabolismo , Sulfonamidas/uso terapéutico , Bloqueadores del Canal de Sodio Activado por Voltaje/metabolismo , Bloqueadores del Canal de Sodio Activado por Voltaje/uso terapéuticoRESUMEN
Selective block of NaV1.7 promises to produce non-narcotic analgesic activity without motor or cognitive impairment. Several NaV1.7-selective blockers have been reported, but efficacy in animal pain models required high multiples of the IC50 for channel block. Here, we report a target engagement assay using transgenic mice that has enabled the development of a second generation of selective Nav1.7 inhibitors that show robust analgesic activity in inflammatory and neuropathic pain models at low multiples of the IC50. Like earlier arylsulfonamides, these newer acylsulfonamides target a binding site on the surface of voltage sensor domain 4 to achieve high selectivity among sodium channel isoforms and steeply state-dependent block. The improved efficacy correlates with very slow dissociation from the target channel. Chronic dosing increases compound potency about 10-fold, possibly due to reversal of sensitization arising during chronic injury, and provides efficacy that persists long after the compound has cleared from plasma.
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Analgésicos/uso terapéutico , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Neuralgia/tratamiento farmacológico , Bloqueadores de los Canales de Sodio/uso terapéutico , Sulfonamidas/uso terapéutico , Analgésicos/farmacocinética , Animales , Sitios de Unión , Células Cultivadas , Células HEK293 , Humanos , Concentración 50 Inhibidora , Ratones , Canal de Sodio Activado por Voltaje NAV1.7/química , Unión Proteica , Bloqueadores de los Canales de Sodio/farmacocinética , Sulfonamidas/farmacocinéticaRESUMEN
Voltage-gated sodium (Nav) channels propagate action potentials in excitable cells. Accordingly, Nav channels are therapeutic targets for many cardiovascular and neurological disorders. Selective inhibitors have been challenging to design because the nine mammalian Nav channel isoforms share high sequence identity and remain recalcitrant to high-resolution structural studies. Targeting the human Nav1.7 channel involved in pain perception, we present a protein-engineering strategy that has allowed us to determine crystal structures of a novel receptor site in complex with isoform-selective antagonists. GX-936 and related inhibitors bind to the activated state of voltage-sensor domain IV (VSD4), where their anionic aryl sulfonamide warhead engages the fourth arginine gating charge on the S4 helix. By opposing VSD4 deactivation, these compounds inhibit Nav1.7 through a voltage-sensor trapping mechanism, likely by stabilizing inactivated states of the channel. Residues from the S2 and S3 helices are key determinants of isoform selectivity, and bound phospholipids implicate the membrane as a modulator of channel function and pharmacology. Our results help to elucidate the molecular basis of voltage sensing and establish structural blueprints to design selective Nav channel antagonists.
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Canal de Sodio Activado por Voltaje NAV1.7/química , Bloqueadores de los Canales de Sodio/química , Bloqueadores de los Canales de Sodio/farmacología , Sulfonamidas/química , Sulfonamidas/farmacología , Tiadiazoles/química , Tiadiazoles/farmacología , Secuencia de Aminoácidos , Membrana Celular/química , Cristalización/métodos , Cristalografía por Rayos X , Análisis Mutacional de ADN , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Canal de Sodio Activado por Voltaje NAV1.7/genética , Percepción del Dolor/efectos de los fármacos , Ingeniería de Proteínas , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/química , Estructura Secundaria de Proteína , Estructura Terciaria de ProteínaRESUMEN
Activation of phenol derivatives with a hypervalent iodine reagent promotes the formation of bicyclic and tricyclic products via a cationic cyclization process. The method allows efficient one-step syntheses of scaffolds present in several natural products and occurs with total stereocontrol, governed by 1,3 allylic strain interactions and by the configuration of the side chain double bonds.
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Yodo/química , Cationes/química , Ciclización , Estructura Molecular , Oxidación-Reducción , EstereoisomerismoRESUMEN
An unprecedented oxidative Prins transformation on phenol derivatives mediated by a hypervalent iodine reagent has been developed. This method allows a rapid access to highly substituted compact systems present in several natural products via a carbon-based addition on an aromatic core. Substitution at each ring position has been demonstrated, enabling synthesis of molecules with up to two contiguous quaternary carbon centers in good yield.
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Mitomycins are a class of very potent antibacterial and anti-cancer compounds having a broad activity against a range of tumours. They have been used in clinics since the 1960's, and the challenges represented by their total synthesis have challenged generations of chemists. Despite these chemical and medicinal features, these compounds, in racemic form, have succumbed to total synthesis only four times over the last 30 years.