Discovery of a selective, state-independent inhibitor of NaV1.7 by modification of guanidinium toxins

Sci Rep. 2020 Sep 9;10(1):14791. doi: 10.1038/s41598-020-71135-2.

Abstract

The voltage-gated sodium channel isoform NaV1.7 is highly expressed in dorsal root ganglion neurons and is obligatory for nociceptive signal transmission. Genetic gain-of-function and loss-of-function NaV1.7 mutations have been identified in select individuals, and are associated with episodic extreme pain disorders and insensitivity to pain, respectively. These findings implicate NaV1.7 as a key pharmacotherapeutic target for the treatment of pain. While several small molecules targeting NaV1.7 have been advanced to clinical development, no NaV1.7-selective compound has shown convincing efficacy in clinical pain applications. Here we describe the discovery and characterization of ST-2262, a NaV1.7 inhibitor that blocks the extracellular vestibule of the channel with an IC50 of 72 nM and greater than 200-fold selectivity over off-target sodium channel isoforms, NaV1.1-1.6 and NaV1.8. In contrast to other NaV1.7 inhibitors that preferentially inhibit the inactivated state of the channel, ST-2262 is equipotent in a protocol that favors the resting state of the channel, a protocol that favors the inactivated state, and a high frequency protocol. In a non-human primate study, animals treated with ST-2262 exhibited reduced sensitivity to noxious heat. These findings establish the extracellular vestibule of the sodium channel as a viable receptor site for the design of selective ligands targeting NaV1.7.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Drug Discovery
  • Ganglia, Spinal / metabolism
  • Guanidine / chemistry*
  • Humans
  • NAV1.1 Voltage-Gated Sodium Channel / chemistry
  • NAV1.2 Voltage-Gated Sodium Channel / chemistry
  • NAV1.3 Voltage-Gated Sodium Channel / chemistry
  • NAV1.4 Voltage-Gated Sodium Channel / chemistry
  • NAV1.5 Voltage-Gated Sodium Channel / chemistry
  • NAV1.6 Voltage-Gated Sodium Channel / chemistry
  • NAV1.7 Voltage-Gated Sodium Channel / chemistry*
  • NAV1.8 Voltage-Gated Sodium Channel / chemistry
  • Protein Structure, Secondary
  • Sodium Channel Blockers / chemistry*
  • Sodium Channel Blockers / pharmacology*

Substances

  • NAV1.1 Voltage-Gated Sodium Channel
  • NAV1.2 Voltage-Gated Sodium Channel
  • NAV1.3 Voltage-Gated Sodium Channel
  • NAV1.4 Voltage-Gated Sodium Channel
  • NAV1.5 Voltage-Gated Sodium Channel
  • NAV1.6 Voltage-Gated Sodium Channel
  • NAV1.7 Voltage-Gated Sodium Channel
  • NAV1.8 Voltage-Gated Sodium Channel
  • Sodium Channel Blockers
  • Guanidine