Developing a selective TRPC3 ion channel inhibitor for epilepsy treatment

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Project Summary Epilepsy is one of the most common brain disorders. Current drugs have limited efficacy. Identifying new targeted drugs that can be used as safer, more effective therapies is in urgent unmet need. Selective inhibition of the transient receptor potential canonical 3 (TRPC3) emerges as a novel strategy to impede epilepsy. However, the currently best selective TRPC3 inhibitor, Pyr3, has poor metabolic stability and has significant safety liabilities. We recently published the discovery of a patented Pyr3 analog, JW-65, which has significantly improved metabolic stability and safety profiles. It has good brain penetration and retention, directly binds to TRPC3, and shows better efficacy than an existing drug phenytoin in a head-to-head comparison in an epilepsy mouse model. SEAK is licensing this patented scaffold and proposes in this Phase I STTR to thoroughly de-risk JW-65 as a potentially viable clinical candidate for targeted epilepsy therapy. Aim 1. Determine toxicological profiles, potential off-targets against a panel of physiologically important targets, major CYP inhibitions and inductions, membrane permeability, transporter effects, plasma binding and stability, and pharmacokinetic (PK) profiles to further de-risk JW-65. We have already confirmed the direct binding to and functional inhibition of TRPC3 by JW-65 and demonstrated its excellent drug- like properties. We have also showed that JW-65 has good PK properties with i.p. injection. In this aim, we will first perform large scale synthesis of JW-65 to support subsequent biological evaluations. We will then comprehensively evaluate its safety, off-targets, ADME properties, and industry standard rat PK (i.v. and oral) profiles to comprehensively de-risk JW-65 as a clinical candidate. Milestones: (1) three grams of JW-65 synthesized and rigorously characterized; (2) demonstrate the safety profiles and drug like properties of JW-65 as a viable candidate; (3) determine PK profiles and oral bioavailability of JW-65. Aim 2. Evaluate in vivo efficacy of JW-65 for its ability to suppress acute seizures in multiple models in both mice and rats. We will first assess the efficacy of JW-65 on acute seizures in rats induced by pilocarpine, using both Pyr3 and benzodiazepines (the first-line drugs for prolonged seizures) as references. To further increase the rigor and avoid any model- or species-specific findings, the anti-seizure effects of JW-65 will be validated in the mouse kainic acid model and flurothyl model. Milestones: (4) demonstrate efficacy against acute pilocarpine seizures in rats (~50% reduction in behavioral seizure scores or EEG spikes); (5) demonstrate efficacy against flurothyl-induced seizures in mice (~50% increase in latencies to the first myoclonic jerk and generalized tonic-clonic seizure); (6) demonstrate efficacy against 6 Hz-induced seizures in mice (~50% decrease in behavioral seizure scores); (7) demonstrate efficacy against spontaneous seizures (~50% decrease in total number of SRSs per day). Future directions: In Phase 2, SEAK will perform comprehensive IND-enabling studies for JW-65.