Treatment with HC-070, a potent inhibitor of TRPC4 and TRPC5, leads to anxiolytic and antidepressant effects in mice

Abstract

BackgroundForty million adults in the US suffer from anxiety disorders, making these the most common forms of mental illness. Transient receptor potential channel canonical subfamily (TRPC) members 4 and 5 are non-selective cation channels highly expressed in regions of the cortex and amygdala, areas thought to be important in regulating anxiety. Previous work with null mice suggests that inhibition of TRPC4 and TRPC5 may have anxiolytic effects.HC-070 in vitroTo assess the potential of TRPC4/5 inhibitors as an avenue for treatment, we invented a highly potent, small molecule antagonist of TRPC4 and TRPC5 which we call HC-070. HC-070 inhibits recombinant TRPC4 and TRPC5 homomultimers in heterologous expression systems with nanomolar potency. It also inhibits TRPC1/5 and TRPC1/4 heteromultimers with similar potency and reduces responses evoked by cholecystokinin tetrapeptide (CCK-4) in the amygdala. The compound is >400-fold selective over a wide range of molecular targets including ion channels, receptors, and kinases.HC-070 in vivoUpon oral dosing in mice, HC-070 achieves exposure levels in the brain and plasma deemed sufficient to test behavioral activity. Treatment with HC-070 attenuates the anxiogenic effect of CCK-4 in the elevated plus maze (EPM). The compound recapitulates the phenotype observed in both null TRPC4 and TRPC5 mice in a standard EPM. Anxiolytic and anti-depressant effects of HC-070 are also observed in pharmacological in vivo tests including marble burying, tail suspension and forced swim. Furthermore, HC-070 ameliorates the increased fear memory induced by chronic social stress. A careful evaluation of the pharmacokinetic-pharmacodynamic relationship reveals that substantial efficacy is observed at unbound brain levels similar to, or even lower than, the 50% inhibitory concentration (IC50) recorded in vitro, increasing confidence that the observed effects are indeed mediated by TRPC4 and/or TRPC5 inhibition. Together, this experimental data set introduces a novel, high quality, small molecule antagonist of TRPC4 and TRPC5 containing channels and supports the targeting of TRPC4 and TRPC5 channels as a new mechanism of action for the treatment of psychiatric symptoms.

Potent, selective, and subunit‐dependent activation of TRPC5 channels by a xanthine derivative

“…Pico145 inhibits all TRPC1/4/5 channels but is more potent against heteromeric channels, and especially TRPC1/4 channels (Rubaiy, Ludlow, Henrot, et al, ). However, the range of potencies of Pico145 against different TRPC1/4/5 tetramers may depend on channel activation mode (Just et al, ; Rubaiy, Ludlow, Henrot, et al, ). The benzothiadiazine derivative BTD activates TRPC5:C5 (EC 50 ~1 μM), TRPC1:C5, and TRPC4:C5 channels, but not TRPC4:C4 or TRPC1:C4 channels (Beckmann et al, ).…”

“…Other promising TRPC1/4/5 activators include the natural product http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10287 (Rubaiy et al, ), the marketed drug http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=2326 (which has limited potency and selectivity but has been used for in vivo studies of TRPC5 channels; Richter, Schaefer, & Hill, ; Zhou et al, ; Zhu et al, ), and the synthetic benzothiadiazine derivative http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10289, which activates TRPC5:C5 (EC 50 ~1 μM), TRPC1:C5, and TRPC4:C5 channels, but not TRPC4:C4 or TRPC1:C4 channels (Beckmann et al, ). The most promising TRPC1/4/5 inhibitors are two closely related xanthines, http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10291 (also called HC‐608) and http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10286 (Figure ; Just et al, ; Rubaiy, Ludlow, Bon, & Beech, ; Rubaiy, Ludlow, Henrot, et al, ), which were originally described in a patent (Chenard & Gallaschun, ). These compounds exhibit (sub)nanomolar potency against TRPC1/4/5 channels, while at 1–2 μM, no significant effects on hundreds of other targets were found (Just et al, ).…”

“…The most promising TRPC1/4/5 inhibitors are two closely related xanthines, http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10291 (also called HC‐608) and http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=10286 (Figure ; Just et al, ; Rubaiy, Ludlow, Bon, & Beech, ; Rubaiy, Ludlow, Henrot, et al, ), which were originally described in a patent (Chenard & Gallaschun, ). These compounds exhibit (sub)nanomolar potency against TRPC1/4/5 channels, while at 1–2 μM, no significant effects on hundreds of other targets were found (Just et al, ). The compounds are orally bioavailable and suitable for in vivo studies (Cheung et al, ; Just et al, ).…”

“…These compounds exhibit (sub)nanomolar potency against TRPC1/4/5 channels, while at 1–2 μM, no significant effects on hundreds of other targets were found (Just et al, ). The compounds are orally bioavailable and suitable for in vivo studies (Cheung et al, ; Just et al, ). Pico145 also distinguishes between different TRPC1/4/5 tetramers, with the highest potency against heteromeric channels (Rubaiy, Ludlow, Henrot, et al, ).…”

“…Although observational clinical studies and changes detected in genetically or pharmacologically modified rodents and/or human tissue suggest multiple physiological roles of TRPC1/4/5 channels (Bon & Beech, 2013;Bröker-Lai et al, 2017;Lau et al, 2016;Lepannetier et al, 2018), disruption of the Trpc4/5 genes (Suresh Babu, Wojtowicz, Birnbaumer, Hecker, & Cattaruzza, 2012) and global expression of a dominant-negative mutant TRPC5 (Sukumar et al, 2012) do not cause catastrophic phenotypes. However, the involvement of TRPC1/4/5 channels in various human diseases-including CNS disorders, kidney disease, cancer, cardiovascular disease, and complications of diabetes -has led these channels to emerge as potential therapeutic targets (Bon & Beech, 2013;Gaunt, Vasudev, & Beech, 2016;Just et al, 2018;Minard et al, 2018;Zhou et al, 2017).…”