Young C

Xenon Pharmaceuticals (Canada)

2
EM Publications
12
h-index
(1,464 citations, 28 total works)

Research Topics

Ion channel regulation and function (13) Neuroscience and Neuropharmacology Research (7) Cholinesterase and Neurodegenerative Diseases (7) Cardiac electrophysiology and arrhythmias (4) Crystallization and Solubility Studies (3)

Erythromelalgia Publications

Selective Na1.7 Antagonists with Long Residence Time Show Improved Efficacy against Inflammatory and Neuropathic Pain.

Bankar G, Goodchild SJ, Howard S, Nelkenbrecher K, Waldbrook M , et al.
Cell reports

Selective block of Na1.7 promises to produce non-narcotic analgesic activity without motor or cognitive impairment. Several Na1.7-selective blockers have been reported, but efficacy in animal pain models required high multiples of the IC 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 IC. 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.

Treatment of Na(v)1.7-mediated pain in inherited erythromelalgia using a novel sodium channel blocker.

Goldberg YP, Price N, Namdari R, Cohen CJ, Lamers MH , et al.
Pain

Mutations in the SCN9A gene leading to deficiency of its protein product, Na(v)1.7, cause congenital indifference to pain (CIP). CIP is characterized by the absence of the ability to sense pain associated with noxious stimuli. In contrast, the opposite phenotype to CIP, inherited erythromelalgia (IEM), is a disorder of spontaneous pain caused by missense mutations resulting in gain-of-function in Na(v)1.7 that promote neuronal hyperexcitability. The primary aim of this study was to demonstrate that Na(v)1.7 antagonism could alleviate the pain of IEM, thereby demonstrating the utility of this opposite phenotype model as a tool for rapid proof-of-concept for novel analgesics. An exploratory, randomized, double-blind, 2-period crossover study was conducted in 4 SCN9A mutation-proven IEM patients. In each treatment period (2days), separated by a 2-day washout period, patients were orally administered XEN402 (400mg twice daily) or matching placebo. In 3 patients, pain was induced by heat or exercise during each treatment arm. A fourth patient, in constant severe pain, required no induction. Patient-reported outcomes of pain intensity and/or relief were recorded, and the time taken to induce pain was measured. The ability to induce pain in IEM patients was significantly attenuated by XEN402 compared with placebo. XEN402 increased the time to maximal pain induction and significantly reduced the amount of pain (42% less) after induction (P=.014). This pilot study showed that XEN402 blocks Na(v)1.7-mediated pain associated with IEM, thereby demonstrating target engagement in humans and underscoring the use of rare genetic disorders with mutant target channels as a novel approach to rapid proof-of-concept.