Clare London

Analgesic Effects of a Substituted N-Triazole Oxindole (TROX-1), a State-Dependent, Voltage-Gated Calcium Channel 2 Blocker

Voltage-gated calcium channel (Cav)2.2 (N-type calcium channels) are key components in nociceptive transmission pathways. Ziconotide, a state-independent peptide inhibitor of Cav2.2 channels, is efficacious in treating refractory pain but exhibits a narrow therapeutic window and must be administered intrathecally. We have discovered an N-triazole oxindole, (3R)-5-(3-chloro-4-fluorophenyl)-3-methyl-3-(pyrimidin-5-ylmethyl)-1-(1H-1,2,4-triazol-3-yl)-1,3-dihydro-2H-indol-2-one (TROX-1), as a small-molecule, state-dependent blocker of Cav2 channels, and we investigated the therapeutic advantages of this compound for analgesia. TROX-1 preferentially inhibited potassium-triggered calcium influx through recombinant Cav2.2 channels under depolarized conditions (IC50 = 0.27 μM) compared with hyperpolarized conditions (IC50 > 20 μM). In rat dorsal root ganglion (DRG) neurons, TROX-1 inhibited ω-conotoxin GVIA-sensitive calcium currents (Cav2.2 channel currents), with greater potency under depolarized conditions (IC50 = 0.4 μM) than under hyperpolarized conditions (IC50 = 2.6 μM), indicating state-dependent Cav2.2 channel block of native as well as recombinant channels. TROX-1 fully blocked calcium influx mediated by a mixture of Cav2 channels in calcium imaging experiments in rat DRG neurons, indicating additional block of all Cav2 family channels. TROX-1 reversed inflammatory-induced hyperalgesia with maximal effects equivalent to nonsteroidal anti-inflammatory drugs, and it reversed nerve injury-induced allodynia to the same extent as pregabalin and duloxetine. In contrast, no significant reversal of hyperalgesia was observed in Cav2.2 gene-deleted mice. Mild impairment of motor function in the Rotarod test and cardiovascular functions were observed at 20- to 40-fold higher plasma concentrations than required for analgesic activities. TROX-1 demonstrates that an orally available state-dependent Cav2 channel blocker may achieve a therapeutic window suitable for the treatment of chronic pain.

Characterization of the Substituted N-Triazole Oxindole TROX-1, a Small-Molecule, State-Dependent Inhibitor of Cav2 Calcium Channels

Biological, genetic, and clinical evidence provide validation for N-type calcium channels (CaV2.2) as therapeutic targets for chronic pain. A state-dependent CaV2.2 inhibitor may provide an improved therapeutic window over ziconotide, the peptidyl CaV2.2 inhibitor used clinically. Supporting this notion, we recently reported that in preclinical models, the state-dependent CaV2 inhibitor (3R)-5-(3-chloro-4-fluorophenyl)-3-methyl-3-(pyrimidin-5-ylmethyl)-1-(1H-1,2,4-triazol-3-yl)-1,3-dihydro-2H-indol-2-one (TROX-1) has an improved therapeutic window compared with ziconotide. Here we characterize TROX-1 inhibition of Cav2.2 channels in more detail. When channels are biased toward open/inactivated states by depolarizing the membrane potential under voltage-clamp electrophysiology, TROX-1 inhibits CaV2.2 channels with an IC50 of 0.11 μM. The voltage dependence of CaV2.2 inhibition was examined using automated electrophysiology. TROX-1 IC50 values were 4.2, 0.90, and 0.36 μM at −110, −90, and −70 mV, respectively. TROX-1 displayed use-dependent inhibition of CaV2.2 with a 10-fold IC50 separation between first (27 μM) and last (2.7 μM) pulses in a train. In a fluorescence-based calcium influx assay, TROX-1 inhibited CaV2.2 channels with an IC50 of 9.5 μM under hyperpolarized conditions and 0.69 μM under depolarized conditions. Finally, TROX-1 potency was examined across the CaV2 subfamily. Depolarized IC50 values were 0.29, 0.19, and 0.28 μM by manual electrophysiology using matched conditions and 1.8, 0.69, and 1.1 μM by calcium influx for CaV2.1, CaV2.2, and CaV2.3, respectively. Together, these in vitro data support the idea that a state-dependent, non–subtype-selective CaV2 channel inhibitor can achieve an improved therapeutic window over the relatively state-independent CaV2.2-selective inhibitor ziconotide in preclinical models of chronic pain.

Imidazopyridines: a novel class of hNav1.7 channel blockers.

A series of imidazopyridines were evaluated as potential sodium channel blockers for the treatment of neuropathic pain. Several members were identified with good hNa(v)1.7 potency and excellent rat pharmacokinetic profiles. Compound 4 had good efficacy (52% and 41% reversal of allodynia at 2 and 4h post-dose, respectively) in the Chung rat spinal nerve ligation (SNL) model of neuropathic pain when dosed orally at 10mg/kg.

Novel N1-(benzyl)cinnamamidine derived NR2B subtype-selective NMDA receptor antagonists

Novel (E)-N(1)-(benzyl)cinnamamidines were prepared and evaluated as NR2B subtype NMDA receptor ligands. Excellent affinity was achieved by appropriate substitution of either phenyl ring. The 2-methoxybenzyl compound 1h had approximately 1,000-fold lower IC(50) in NR2B than NR2A-containing cells. Replacement of the styryl unit by 2-naphthyl was well tolerated.

Discovery of Benzimidazole CYP11B2 Inhibitors with in Vivo Activity in Rhesus Monkeys

We report the discovery of a benzimidazole series of CYP11B2 inhibitors. Hit-to-lead and lead optimization studies identified compounds such as 32, which displays potent CYP11B2 inhibition, high selectivity versus related CYP targets, and good pharmacokinetic properties in rat and rhesus. In a rhesus pharmacodynamic model, 32 produces dose-dependent aldosterone lowering efficacy, with no apparent effect on cortisol levels.

A novel benzazepinone sodium channel blocker with oral efficacy in a rat model of neuropathic pain

A series of benzazepinones were synthesized and evaluated for block of Nav1.7 sodium channels. Compound 30 from this series displayed potent channel block, good selectivity versus other targets, and dose-dependent oral efficacy in a rat model of neuropathic pain.

Imidazopyridyl compounds as aldosterone synthase inhibitors

The inhibition of aldosterone synthase (CYP11B2) may be an effective treatment of hypertension and heart failure, among other ailments. Previously reported benzimidazole CYP11B2 inhibitors led the way for bioisosteric imidazopyridines that are both potent and selective over CYP11B1.

3-Amino-1,5-benzodiazepinones: Potent, state-dependent sodium channel blockers with anti-epileptic activity

A series of 3-amino-1,5-benzodiazepinones were synthesized and evaluated as potential sodium channel blockers in a functional, membrane potential-based assay. One member of this series displayed subnanomolar, state-dependent sodium channel block, and was orally efficacious in a mouse model of epilepsy.

Design, Synthesis, and Evaluation of Novel and Selective G-protein Coupled Receptor 120 (GPR120) Spirocyclic Agonists

Type 2 diabetes mellitus (T2DM) is an ever increasing worldwide epidemic, and the identification of safe and effective insulin sensitizers, absent of weight gain, has been a long-standing goal of diabetes research. G-protein coupled receptor 120 (GPR120) has recently emerged as a potential therapeutic target for treating T2DM. Natural occurring, and more recently, synthetic agonists have been associated with insulin sensitizing, anti-inflammatory, and fat metabolism effects. Herein we describe the design, synthesis, and evaluation of a novel spirocyclic GPR120 agonist series, which culminated in the discovery of potent and selective agonist 14. Furthermore, compound 14 was evaluated in vivo and demonstrated acute glucose lowering in an oral glucose tolerance test (oGTT), as well as improvements in homeostatic measurement assessment of insulin resistance (HOMA-IR; a surrogate marker for insulin sensitization) and an increase in glucose infusion rate (GIR) during a hyperinsulinemic euglycemic clamp in diet-induced obese (DIO) mice.

Discovery and Pharmacology of a Novel Class of Diacylglycerol Acyltransferase 2 Inhibitors

DGAT2 plays a critical role in hepatic triglyceride production, and data suggests that inhibition of DGAT2 could prove to be beneficial in treating a number of disease states. This article documents the discovery and optimization of a selective small molecule inhibitor of DGAT2 as well as pharmacological proof of biology in a mouse model of triglyceride production.