Characterization of CHK-336, A First-in-Class, Liver-Targeted, Small Molecule Lactate Dehydrogenase Inhibitor for Hyperoxaluria Treatment

Background: Primary hyperoxalurias 1-3 (PH1-3) are genetic diseases defined by elevated hepatic oxalate production and increased incidence of calcium oxalate kidney stones and potentially kidney failure. There are two approved agents available for PH1, and no approved therapies for PH2 or PH3. Lactate dehydrogenase A (LDHA) catalyzes the final step in hepatic oxalate synthesis and represents a potential therapeutic target for PH and other forms of hyperoxaluria associated with increased oxalate production. Methods: Potent and selective LDH inhibitors with liver-targeted tissue distribution were identified and characterized in enzymatic, cellular, and in vivo models. Results: We identified CHK-336, a novel oral small molecule that demonstrates potent and selective inhibition of the human LDH enzyme and its activity in hepatocyte assays across multiple species, including hepatocytes isolated from PH1 mice. CHK-336 demonstrated a favourable liver-distribution profile in mice, rats, and monkeys that was dependent on hepatic uptake by OATP transporters and target-mediated drug binding. In a rat pharmacodynamic model, CHK-336 inhibited conversion of 13 C2-glycolate to 13 C2-oxalate in a dose-dependent manner. In a PH1 mouse model, once-daily oral dosing of CHK-336 produced robust and dose-dependent reductions in urinary oxalate to the normal range. Seven days of treatment with CHK-336 also resulted in a significant reduction in urinary oxalate in a PH2 mouse model. Conclusions: In conclusion, CHK-336 is a potent, liver-targeted, small molecule LDH inhibitor that suppressed urinary oxalate production in a rat pharmacodynamic model and mouse models of PH1 and PH2.