Cross-species extrapolation of biological data to guide the environmental safety assessment of pharmaceuticals - The state of the art and future priorities

Abstract

The extrapolation of biological data across species is a key aspect of biomedical research and drug development. In this context, comparative biology considerations are applied with the goal of understanding human disease and guiding the development of effective and safe medicines. However, the widespread occurrence of pharmaceuticals in the environment and the need to assess the risk posed to wildlife has prompted a renewed interest in the extrapolation of pharmacological and toxicological data across the entire tree of life. To address this challenge, a biological 'read-across' approach, based on the use of mammalian data to inform toxicity predictions in wildlife species, has been proposed as an effective way to streamline the environmental safety assessment of pharmaceuticals. Yet, how effective has this approach been, and are we any closer to being able to accurately predict environmental risk based upon known human risk? Here, we discuss the main theoretical and experimental advancements achieved in the last ten years of research in this field. We propose that a better understanding of the functional conservation of drug targets across species, and of the quantitative relationship between target modulation and adverse effects, should be considered as future research priorities. This pharmacodynamic focus should be complemented with the application of higher throughput experimental and computational approaches to accelerate the prediction of internal exposure dynamics. The translation of comparative (eco)toxicology research into real-world applications, however, relies on the (limited) availability of experts with the skill set needed to navigate the complexity of the problem; hence, here we also call for synergistic multi-stakeholder efforts to support and strengthen comparative toxicology research and education at a global level.