Shanghai Pharma Biotherapeutics Usa, Inc.

SPH3127, a newly developed oral nonpeptide direct renin inhibitor with good tolerance and favorable ADME (absorption distribution metabolism excretion) properties in preclinical species, is now being evaluated in phase Ι clinical trial. In this work, the subchronic toxicity of SPH3127 in Sprague-Dawley rats and cynomolgus monkeys has been characterized. Rats and monkeys received SPH3127 orally (30, 300, 900 and 20, 100, 450 mg/kg/day, respectively) on a consecutive daily dosing schedule for 28 days followed by a 28-days recovery period for one third of the animals. The adverse effects of SPH3127 on rats and monkeys mainly included kidney and cardiovascular toxicity, which were consistent with pharmacologic perturbations of physiologic processes associated with the intended molecular targets for this class of renin signaling inhibitors. Moderate liver weight increases accompanied by CYP3A induction were seen in 300 and 900 mg/kg/day rats but not in monkeys or in vitro human hepatocytes. One 450 mg/kg/day monkey died early at day 23 with apparent myelosuppression characterized by atrophy of thymus and spleen, and the relevance to the action of SPH3127 remained unclear. Most of the treatment-induced effects were reversible upon discontinuation of treatment. The no-observed-adverse-effect level (NOAEL) of SPH3127 was determined to be 30 mg/kg/day for Sprague-Dawley rats and 20 mg/kg/day for cynomolgus monkeys based on the kidney and cardiovascular changes found at mid- and high-dose animals.