The Endothelin

Zibotentan, an endothelin-A receptor antagonist, has been used in the treatment of various cardiovascular disorders and neoplasia. Castrated athymic nude mice receiving zibotentan for a preclinical xenograft efficacy study experienced weight loss, gastrointestinal bloat, and the presence of an audible respiratory click. Human side effects have been reported in the nasal cavity, so we hypothesized that the nasal cavity is a target for toxicity in mice receiving zibotentan. Lesions in the nasal cavity predominantly targeted olfactory epithelium in treated mice and were more pronounced in castrated animals. Minimal lesions were present in vehicle control animals, which suggested possible gavage-related reflux injury. The incidence, distribution, and morphology of lesions suggested direct exposure to the nasal mucosa and a possible systemic effect targeting the olfactory epithelium, driven by a type 2 immune response, with group 2 innate lymphoid cell involvement. Severe nasal lesions may have resulted in recurrent upper airway obstruction, leading to aerophagia and associated clinical morbidity. These data show the nasal cavity is a target of zibotentan when given by gavage in athymic nude mice, and such unanticipated and off-target effects could impact interpretation of research results and animal health in preclinical studies