This week, the scientific journal Nature featured two comment articles with opposite perspectives about the role of animals in biomedical research: K. C. Kent Lloyd, from the University of California, Davis, argued that ending animal research isn’t the answer for advancing biomedical research, while Todd J. Herron, from Greenstone Biosciences, California, and co-authors, wrote an opinion article that, by omitting any reference to the limitations of new approach methodologies (NAMs), could suggest that these tools could replace all animal-based science.  

While the continued development of NAMs — including models such as cell cultures and organoids that attempt to mimic human tissues, and computational approaches — has contributed to reducing the use of animals in certain areas of research, the use of animals is necessary to answer many scientific questions. NAMs are unable to effectively predict whole-organism responses and higher functions such as complex immune reactions or cognitive processes.  

Moreover, the use of NAMs and animals in research is complementary, and animals should be used only when no alternative is available, as regulated by the European Union under the EU Directive on the protection of animals used for scientific purposes. However, Herron’s comment could suggest that research using animals is non-innovative and he directly blames experiments in animal models for the failure of around 86% of drug candidates in human clinical trials. While this figure is correct, the interpretation is simplistic. In fact, in the article cited to make this claim, many of the factors that could contribute to this high rate are discussed, including the fact that flawed experimental design in clinical trials is also one of the big culprits in translation failure. The same source also states that drug candidates found to be toxic in animals never advance to human trials and cannot be measured in human trial outcomes. 

While it is important to continue supporting the development, validation and implementation of NAMs, as K. C. Kent Lloyd stated: “All models — whether they are NAMs or inbred mice — should be updated, refined or replaced as tools and data emerge that allow researchers to better match models to the human system they are trying to investigate.” The discussion should not be framed as “one versus the other” but rather focus on selecting the most appropriate model to answer each scientific question. Moreover, the implication that animal research is outdated is also a deeply false argument, as studies using animals are now highly sophisticated and take advantage of all the latest scientific knowledge and revolutionary technologies. In fact, NAMs are only possible because they use, at their core, animal research findings. 

One thing is certain: a polarised and non-transparent discourse not only confuses and misinforms the public and decision-makers but can also fuel an anti-science sentiment that puts at risk biomedical research, public health and the development of new life-changing therapies.