OxDc-A0: an oral gastro-tolerant oxalate decarboxylase for treating secondary hyperoxaluria

Secondary hyperoxaluria is an acquired oxalate metabolic disorder characterized by increased urinary oxalate excretion. Reducing exogenous oxalate absorption through enzyme therapy represents a promising therapeutic strategy. However, the extremely acidic pH and protease-rich environment of the upper gastrointestinal tract pose major obstacles for the oral administration of protein therapeutics. OxDc-A0, a novel gastro-tolerant recombinant oxalate decarboxylase, can degrade oxalate in the stomach, thereby limiting the oxalate pool in the gastrointestinal tract and reducing oxalate absorption and urinary excretion. This study aimed to investigate the pharmacodynamics, pharmacokinetics, and safety profile of OxDc-A0 to assess its drug likeliness. The pharmacodynamics were evaluated in vitro and in hyperoxaluria beagle dog model induced by a high-oxalate diet. OxDc-A0 exhibited excellent gastric tolerance and significant efficacy in reducing urinary oxalate excretion in the dog model with hyperoxaluria. The safety of OxDc-A0 was evaluated in Sprague-Dawley rats, beagle dogs, and golden hamsters according to the guidelines for preclinical safety studies. No adverse effects were observed on the central nervous, cardiovascular, or respiratory system in rats or dogs treated orally with OxDc-A0 up to 37,500 U/kg. Pharmacokinetic studies showed that OxDc-A0 is non-systemically absorbed and is mainly distributed in the gastrointestinal tract. Toxicological studies showed that OxDc-A0 has excellent tolerance, with a NOAEL of 37,500 U/kg/day in both rats and dogs. The maximum tolerated dose was ≥ 105,000 U/kg in rats and ≥ 87,000 U/kg in dogs. Overall, OxDc-A0 shows great potential as a new drug candidate for treating secondary hyperoxaluria.