Minimising animal testing of chemicals and pharmaceuticals is a longstanding challenge. Animal models can help explore how molecules interact with the complex physiology of an entire organism, which is difficult to capture using cell or tissue-based experiments. But there are obvious ethical concerns around animal research, along with significant and unpredictable differences between animal and human physiology that can mean results fail to translate to humans, contributing to expensive clinical trial failures.
Significant progress has been made in recent years in establishing New Approach Methodologies (NAMs) – alternatives that potentially give a more realistic view of how molecules interact with humans, without the need for animal experiments.
Adopting NAMs requires multi-pronged cooperation. Scientists developing the tests must produce convincing evidence to validate that the test is more reliable and useful than an animal experiment. They must also make sure that the people who need to use it know about it (beyond simply publishing a paper) and understand why they should make the effort to switch. They must not only convince toxicologists in academia and industry, but also regulators around the world.
Regulatory guidelines have been slowly shifting in support of NAMs. A recent review in Science outlines details of emerging methods, as well as the evolution in regulatory and ethical frameworks that are enabling the transition. The US Environmental Protection Agency in January committed to a goal of ending animal testing by 2035, while the UK government outlined its strategy for replacing animals in science in November 2025. The EU has a longstanding push towards reducing animal requirements.
In March, the US Food and Drug Administration issued new draft guidance on how to validate alternatives to animal testing. Also in March, the UK Medicines and Healthcare products Regulatory Agency began offering early reviews of non-animal data and clarified its assessment criteria. Meanwhile, the European Medicines Agency began consultation on using virtual control groups for toxicology testing to reduce the numbers of rats used in preclinical dose-range finding studies for new drugs.
The fact that several of the world’s most influential regulators are all moving in similar directions is important, since animal testing has a socio-technological lock-in to overcome. The infrastructure, momentum and mindset built around animal testing means that even demonstrably superior technology can struggle to displace it. If regulators in the EU, for instance, will accept a non-animal testing scheme, but the US still requires animal tests, then companies will still do the animal tests. Some large, well-resourced companies might do the non-animal method alongside, but this is additional expense, so many will revert to the familiar animal studies.
It therefore requires a concerted and sustained policy push to overcome the activation barrier imposed by the established testing and regulatory environment. That appears to be coming together, but it can easily be derailed as political priorities change.
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