Setanaxib

Setanaxib (GKT137831) is the first NOX-isoform-selective inhibitor to advance from preclinical evaluation to human clinical trials and remains the most clinically developed pharmacological agent targeting the NADPH oxidase family. Identified through a high-throughput screening campaign at Genkyotex SA (Archamps, France) and optimized from the lead compound GKT136901 through structure-activity relationship exploration of the pyrazolopyridine dione scaffold, setanaxib inhibits NOX1 and NOX4 with inhibition constants (Ki) of 110 nM and 140 nM, respectively, while demonstrating approximately 15-fold selectivity over NOX2 (Ki approximately 1750 nM) and approximately 3-fold selectivity over NOX5 (Ki approximately 410 nM). The compound blocks NADPH oxidase-mediated generation of reactive oxygen species (ROS), a signaling mechanism implicated as a central driver of fibrogenesis in liver, kidney, and lung; of oxidative stress in cardiovascular and metabolic disease; and of cancer-associated fibroblast differentiation in the tumor microenvironment.

Setanaxib received orphan drug designation from the United States Food and Drug Administration and the European Medicines Agency in 2010 for idiopathic pulmonary fibrosis and FDA Fast Track designation in 2021 for primary biliary cholangitis (PBC). The clinical development program encompasses six distinct indications. In PBC, the Phase 2b TRANSFORM trial (NCT05014672) in 76 patients with inadequate response to ursodeoxycholic acid demonstrated statistically significant reduction in serum alkaline phosphatase (ALP) of 19 percent (1600 mg arm) and 14 percent (1200 mg arm) over 24 weeks, meeting the primary endpoint and supporting progression toward registrational studies. An earlier Phase 2 trial (NCT03226067) in 111 PBC patients reported a 12.9 percent ALP reduction (p < 0.002 vs placebo) and a 22 percent reduction in liver stiffness among patients with stage 3 fibrosis. In diabetic nephropathy, a Phase 2 trial (NCT02010242) in 136 patients with type 2 diabetes and macroalbuminuria did not meet the primary endpoint of albuminuria reduction over 12 weeks, though anti-fibrotic biomarker signals were observed. In recurrent or metastatic squamous cell carcinoma of the head and neck (HNSCC), a Phase 2 trial of setanaxib (800 mg in the published literature) combined with pembrolizumab reported median progression-free survival of 5.0 months versus 2.9 months for pembrolizumab plus placebo (hazard ratio 0.58), with 9-month overall survival rates of 88 percent versus 58 percent (hazard ratio 0.45). In Alport syndrome, a Phase 2a trial (NCT06274489) in 20 patients demonstrated safety and a 15 percent mean reduction in urine protein-to-creatinine ratio versus placebo at 24 weeks. Phase 2 trials in idiopathic pulmonary fibrosis (NCT03865927; NIH-funded, 60 patients) and in type 1 diabetes-related kidney disease (JDRF-funded) are ongoing.

Pharmacokinetics in humans demonstrate rapid oral absorption (time to peak concentration 0.5 to 3 hours), an elimination half-life of 8 to 14 hours supporting twice-daily dosing, and metabolism principally through uridine 5'-diphospho-glucuronosyltransferase 1A9 (UGT1A9) to an N-glucuronide metabolite and through cytochrome P450 3A4 (CYP3A4) to the active demethylated metabolite GKT138184 (elimination half-life 9 to 12 hours). The compound has been well tolerated across all completed Phase 1 and Phase 2 studies, with no dose-limiting toxicity identified at doses up to 1600 mg and no clinically significant safety signals. Setanaxib is not approved for clinical use in any jurisdiction. It is available as a research-grade preparation from multiple chemical suppliers; investigators should obtain analytical confirmation of identity and purity on every lot.