Recent years have seen a growing movement away from animal testing and toward models that more closely replicate human physiology. This shift aims to protect animal welfare while concurrently addressing the poor translational value of animal models in biomedical research and drug development.
The regulatory landscape surrounding animal testing in preclinical development and chemical safety assessments has also shifted significantly in recent years. Regulatory bodies on both sides of the Atlantic, including the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA), have encouraged the phasing out of animal models in favor of in vitro models and New Approach Methodologies (NAMs).
Despite the revised regulatory guidelines and innovations in alternative methods, the reduction of animal testing across biomedical research, drug development, and chemical safety assessments has remained slow. Meanwhile, many in vitro systems still include animal-derived materials. So, what more can be done to reduce our industry’s reliance on animals?
Regulatory push to avoid animal use
Both the EMA and FDA have taken significant steps to minimize animal testing and expedite the development and implementation of in vitro methods, particularly in the development of new drugs. The EMA, through its Innovation Task Force, has been proactive in encouraging the adoption of the 3Rs (Replacement, Reduction, and Refinement).1 In 2021, the European Union issued a new directive to encourage NAMs to be incorporated in the assessment of the safety and efficacy of new medicines to replace or reduce animal use.2
In the United States, regulatory action has gone one step further—the FDA Modernization Act 2.0. Signed into law in December 2022, it abolished the requirement for animal testing in preclinical drug development.3 This marked a regulatory paradigm shift aimed at reducing the ethical and financial burdens of animal testing.
The picture is also beginning to change with regard to chemical safety assessments. The U.S. Environmental Protection Agency (EPA) has set ambitious goals to reduce animal testing by 30% by 2025 and eliminate it entirely by 2035. In Europe, the European Chemicals Agency, under the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation, mandates that animal testing should be used only as a last resort. Despite this shift in regulation, however, the reduction of animal tests across the board has been minimal.
Where and why does animal testing remain commonplace?
There are two areas where animal testing remains prevalent: drug development and
chemical safety assessment.
In pharmaceuticals, new drugs undergo a long and costly development process that includes extensive preclinical efficacy, safety, and pharmacokinetic testing, followed by clinical trials. In particular, preclinical toxicity testing has traditionally relied heavily on animal models to assess factors including chronic and acute systemic toxicity, local toxicity and irritation, and other toxic effects. Using in vivo models for these tests is not only ethically challenging, but also provides poor predictive value of human responses. For some preclinical assessments, animal testing is still mandatory for obtaining marketing authorization in the European Union, and while the updated FDA legislation no longer requires animal tests where approved NAMs can be employed, many developers still favor long-established animal models.
Chemical safety testing is another area of concern. The expanding use of chemicals in everyday products, from pesticides to food preservatives, demands ever more rigorous toxicological testing to ensure human and environmental safety. Driven by an increased awareness of the acute and chronic effects of chemical exposure, safety assessment of chemicals requires the interrogation of a host of factors like genotoxicity, carcinogenicity, and endocrine disruption. Despite the E.U. ban on animal testing for cosmetics since 2013 and the EPA setting clear targets to reduce animal testing in chemical safety assessments, animals are still required to test the long-term effects of chemicals.
Barriers to the adoption of non-animal methods
One major challenge to overcome in the replacement and reduction of animal testing is the painstaking validation of alternative methods. Although many advanced human cell and 3D culture–based methods have been developed, very few have been validated for regulatory use. Validation is crucial to ensure that these models produce consistent, reliable, and reproducible results, which is essential for their acceptance in regulatory frameworks.
Pharmaceutical companies often use advanced human cell models in drug discovery for their own purposes, but too often keep these platforms proprietary rather than submitting them for regulatory validation. This isolationist approach hinders the broader adoption of validated alternative methods, as the innovations remain within the confines of the company and are not shared with the larger scientific community. As a result, the potential benefits of these advancements are not fully realized, and progress in the field is slowed.
Additionally, academic incentives for validation are lacking. The academic system tends to prioritize novel findings and their dissemination in high-impact publications, which means that validation, which is costly and time consuming and yields few publications, is often undervalued and underfunded. Addressing these issues will require a concerted effort from both the scientific and regulatory communities to prioritize and support the validation of alternative methods.
Freeing animals from vials
Although advanced in vitro models provide effective alternatives to animal testing, many of these models still heavily rely on animal-derived materials. A great number of animals are sacrificed in the production of antibodies, cell culture media, plasticware coatings, growth factors, and importantly for many cell culture applications, the extracellular matrix in which cells are cultivated. According to estimates, the number of animals used in such products is significantly greater than the number of the animals used for in vivo tests.4
To address this substantial and sometimes invisible use of animals, the industry should encourage the development and adoption of animal-free cell culture materials and reagents. Adopting animal-free alternatives such as nanofibrillar cellulose (NFC), derived from wood, can make a significant difference. For example, when an animal-derived 3D cell culture matrix isolated from a mouse tumor is used, a typical microwell plate requires 5 mL, equating to one mouse. This mouse could be saved by instead opting for an animal-free matrix made from NFC and water. When scaled up to 1 m3 of fresh birch, the NFC approach could replace 1.5 million mice.
Advanced cell models should provide an answer to reducing animal use in the long run, when they are validated. In the meantime, animal-free materials and reagents provide a quick and significant step toward the goal we share.
An ever-changing landscape
Although significant progress has been made toward reducing animal testing, much work remains. Continued efforts in validating alternative methods and raising awareness about the hidden use of animals in reagents are essential. The future of drug development and toxicology screening lies in innovative in vitro methodologies that promise faster, safer, and more ethical drug development. By embracing these changes, the pharmaceutical industry can move closer to a sustainable future where human-relevant models replace animal testing, fostering more ethical and effective management of the drug development pipeline.
Johana Kuncova-Kallio, PhD, is the director of UPM Biomedicals, UPM-Kymmene.
References
1. EMA Press Office. EMA implements new measures to minimize animal testing during medicines development. Published: September 21, 2021. Accessed July 10, 2024. https://www.ema.europa.eu/en/news/ema-implements-new-measures-minimise-animal-testing-during-medicines-development
2. Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the Protection of Animals Used for Scientific Purposes. Off. J. Eur. Union. 2010; 276: 33–79. https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:276:0033:0079:en:PDF
3. FDA Modernization Act 2.0. 2022. https://www.congress.gov/bill/117th-congress/senate-bill/5002
4. Cassotta M, Bartnicka JJ, Pistollato F, et al. A worldwide survey on the use of animal-derived materials and reagents in scientific experimentation. Eng. Life Sci. 2022;22(9): 564–583.
