RESUMEN
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.
Asunto(s)
Guanidina/química , Canal de Sodio Activado por Voltaje NAV1.7/química , Bloqueadores de los Canales de Sodio/química , Bloqueadores de los Canales de Sodio/farmacología , Animales , Descubrimiento de Drogas , Ganglios Espinales/metabolismo , Humanos , Canal de Sodio Activado por Voltaje NAV1.1/química , Canal de Sodio Activado por Voltaje NAV1.2/química , Canal de Sodio Activado por Voltaje NAV1.3/química , Canal de Sodio Activado por Voltaje NAV1.4/química , Canal de Sodio Activado por Voltaje NAV1.5/química , Canal de Sodio Activado por Voltaje NAV1.6/química , Canal de Sodio Activado por Voltaje NAV1.8/química , Estructura Secundaria de ProteínaRESUMEN
NaV1.7 is a particularly compelling target for the treatment of pain. Herein, we report the discovery and evaluation of a series of piperazine amides that exhibit state-dependent inhibition of NaV1.7. After demonstrating significant pharmacodynamic activity with early lead compound 14 in a NaV1.7-dependent behavioural mouse model, we systematically established SAR trends throughout each sector of the scaffold. The information gleaned from this modular analysis was then applied additively to quickly access analogues that encompass an optimal balance of properties, including NaV1.7 potency, selectivity over NaV1.5, aqueous solubility, and microsomal stability.
