Vascular origin of vildagliptin-induced skin effects in Cynomolgus monkeys: pathomechanistic role of peripheral sympathetic system and neuropeptide Y.

The purpose of this article is to characterize skin lesions in cynomolgus monkeys following vildagliptin (dipeptidyl peptidase-4 inhibitor) treatment. Oral vildagliptin administration caused dose-dependent and reversible blister formation, peeling and flaking skin, erosions, ulcerations, scabs, and sores involving the extremities at ≥5 mg/kg/day and necrosis of the tail and the pinnae at ≥80 mg/kg/day after 3 weeks of treatment. At the affected sites, the media and the endothelium of dermal arterioles showed hypertrophy/hyperplasia. Skin lesion formation was prevented by elevating ambient temperature. Vildagliptin treatment also produced an increase in blood pressure and heart rate likely via increased sympathetic tone. Following treatment with vildagliptin at 80 mg/kg/day, the recovery time after lowering the temperature in the feet of monkeys and inducing cold stress was prolonged. Ex vivo investigations showed that small digital arteries from skin biopsies of vildagliptin-treated monkeys exhibited an increase in neuropeptide Y-induced vasoconstriction. This finding correlated with a specific increase in NPY and in NPY1 receptors observed in the skin of vildagliptin-treated monkeys. Present data provide evidence that skin effects in monkeys are of vascular origin and that the effects on the NPY system in combination with increased peripheral sympathetic tone play an important pathomechanistic role in the pathogenesis of cutaneous toxicity.

Investigative safety science as a competitive advantage for Pharma.

INTRODUCTION: Following a US National Academy of Sciences report in 2007 entitled "Toxicity Testing of the 21st Century: a Vision and a Strategy," significant advances within translational drug safety sciences promise to revolutionize drug discovery and development. The purpose of this review is to outline why investigative safety science is a competitive advantage for the pharmaceutical industry. AREAS COVERED: The article discusses the essential goals for modern investigative toxicologists including: cross-species target biology; molecular pathways of toxicity; and development of predictive tools, models and biomarkers that allow discovery researchers and clinicians to anticipate safety problems and plan ways to address them, earlier than ever before. Furthermore, the article emphasizes the importance of investigating unanticipated clinical safety signals through a combination of mechanistic preclinical studies and/or molecular characterization of clinical samples from affected organs. EXPERT OPINION: The traditional boundaries between pharma industry teams focusing on safety/efficacy and preclinical/clinical development are rapidly disappearing in favor of translational safety science-centric organizations with a vision of bringing more effective medicines forward safely and quickly. Comparative biology and mechanistic toxicology approaches facilitate: i) identifying translational safety biomarkers; ii) identifying new drug targets/indications; and iii) mitigating off-target toxicities. These value-adding safety science contributions will change traditional toxicologists from side-effect identifiers to drug development enablers.