New opportunities and current challenges using animal models for the discovery of novel countermeasures for acute radiation syndrome

Introduction: The availability of well-characterized small and large animal models is critical for the discovery and development of new drugs that counter the negative health effects of unwanted, acute ionizing radiation exposures. Area covered: This article discusses the opportunities and challenges of small and large animal models for the development and regulatory approval of novel drugs for acute radiation syndrome (ARS). Various animal models of ARS have been analyzed for both strengths and weaknesses relative to the development of drugs for ARS following the Food and Drug Administration (FDA) Animal Rule. This article is based on a search of literature utilizing PubMed, covering the period up to March 2025. Expert opinion: Relative to large animal models, the rhesus macaque model is currently the most used and best characterized for translational relevance. Other large animal models (e.g. minipig) are currently used as well to evaluate other specific types of acute injury, such as cutaneous injuries. Due to the limited supply of rhesus macaques for studying radiation injury and countermeasure development, it is of some urgency to further characterize and consider the use of alternative models, especially large animal models, for advanced research and subsequent regulatory approval of ARS countering drugs.