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Animal testing is crucial for measuring the efficacy and safety of new treatments. It is also a step that everyone would like to avoid as much as possible for economic, regulatory, and ethical reasons. But what are the alternatives, and can they really reduce the use of animals in drug development?
Before drug developers let a treatment anywhere near humans for testing, they need evidence that it is likely to be both safe and effective. This has historically been done by testing the drug on living animals (in vivo), and more recently in human cells or tissue in a dish (in vitro).
In general terms, in vitro testing is cheaper and quicker than in vivo, but testing in animals, most commonly mice, is thought to give a better picture of how a treatment behaves in a living organism. While the predictive value of animal models does vary depending on the disease and treatments in question, a company must always show that its treatment is safe and effective in animal models to overcome regulatory hurdles.
But with advances in biotechnology and artificial intelligence (AI), we can now better mimic human organs and physiology; if these technologies prove better than animal testing at predicting the effects of a drug on the human body, they could eventually replace some of the animal testing currently required in drug development.
While it is currently uncertain whether animal disease models can ever be fully replaced, new approach methodologies are beginning to change the face of drug development and reduce our reliance on animal models. Not only does this solve an ethical dilemma, but it could also make it cheaper, quicker, and more effective to get new disease treatments into the clinic and eventually to patients.
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The recent push to phase out animal testing in the U.S. and the EU
During President Donald Trump’s first term in office, the Environmental Protection Agency (EPA) announced a plan to reduce animal testing by 30% by 2025 and end it altogether by 2035. President Joe Biden then continued to push this aim, signing a new law in 2023 that eliminated the requirement that drugs need to be tested on animals before entering human trials. And, since Trump was returned to office earlier this year, there has been another big push from his administration to put an end to animal testing in the U.S.
In April 2025, the U.S. Food and Drug Administration (FDA) announced a plan to phase out the animal testing requirement for monoclonal antibodies and other drugs, instead promoting the use of new approach methodologies like lab-grown human tissues, organ-on-a-chip systems, and AI-based models. This shift, which began immediately for Investigational New Drug (IND) applications, aims to improve drug safety and accelerate the evaluation process, while reducing animal experimentation, lowering research and development (R&D) costs, and ultimately, drug prices.
Meanwhile, in July, the Foundation for the National Institutes of Health (FNIH) – a congressionally mandated nonprofit that supports the mission of the NIH – said that it is managing a new program to advance innovative laboratory technologies that model human biology, enabling faster and less expensive testing. The initiative, called the Validation and Qualification Network (VQN), brings together more than 40 partners from different organizations, from regulators like the FDA and European Commission, to big pharma companies like Sanofi, Novo Nordisk, and GSK. Essentially, the VQN is developing individual projects to help streamline regulatory approvals for therapies and compounds that are eventually tested using these new technologies, including activities such as the establishment of common data elements and standardized results reporting.
Dr. Laura Alvarez, Cruelty Free International’s deputy director of Science and Regulatory Affairs, told Labiotech that these agency-led initiatives in the U.S. are encouraging and meaningful steps forward. “They signal a growing recognition that modern, non-animal methods can play a more central role in ensuring the safety and effectiveness of new drugs. They provide a useful framework for change, and we’re encouraged to see the agencies addressing many of the longstanding concerns raised by Cruelty Free International, including the need for fixed deadlines to replace animal tests, improved tracking of animal use, increased funding and meaningful incentives for non-animal methods, and recognition of the scientific limitations of animal models.
“If these plans succeed in their aim to make animal tests the exception rather than the norm in the next few years, they could help build broader confidence in non-animal methods and support greater alignment across federal agencies.”
Alvarez’s Cruelty Free International is also part of a coalition of animal protection non-governmental organizations (NGOs) advising the European Commission on what it needs to do to create an impactful and effective roadmap on the phase-out of animal testing in chemical safety assessment, which is due to be published in Q1 2026.
“The roadmap, which was a direct response to our 2021 European Citizens’ Initiative, ‘Save Cruelty Free Cosmetics – Commit to a Europe Without Animal Testing’, was very welcome,” said Alvarez. “The ECI was signed by over 1.2 million European citizens, giving the European Parliament the strongest possible message that people want animal testing in Europe to end. This message was backed by MEPs who overwhelmingly supported the creation of the roadmap even before the Commission made its commitment.”
However, she added that there are concerns that the European Commission’s proposals could lack the impetus to drive concrete change and that it will fail to address the unresolved misalignment between the Cosmetic Products Regulation (CPR), which contains the bans on animal testing for cosmetics, and Europe’s main chemicals legislation, REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). Alvarez explained that, in this case, the CPR is meant to take precedence in the regulation of cosmetics, but the European Chemicals Agency (ECHA) has demanded that tests on animals be performed under REACH for cosmetic-only ingredients.
Alvarez confirmed that the REACH revision is due to be published by the end of the year, and the CPR is currently under consideration for revision. “By addressing the misalignment in these revisions and taking clear action in favour of phasing out animal testing, the Commission would demonstrate a concrete commitment to act on the spirit of the roadmap.”
Alternatives to animal testing: A look at the best new approach methodologies
Nowadays, there are several new approach methodologies that can be used as alternatives to animal testing. “Modern approaches draw on a wide range of technologies, from advanced cell and tissue models to computer simulations and other innovative tools designed to reflect human biology,” explained Alvarez. “These methods can generate more accurate, timely, and cost-effective data than the outdated animal-based system, paving the way for safer and more effective medicines.”
Here, we look at some of the most promising approaches currently available.
Tissue bioprinting
3D printing has revolutionized the tech world for its potential to produce complex machine parts from a digital file. The same is starting to be done using bioinks that carry cells to make living tissues.
Tissue bioprinting can be used to replicate the 3D structure of a human tissue, which provides a lot more information about a drug’s effect than just using human cell cultures. One particular area of interest for the field is cosmetics; companies like L’Oréal, Chanel, and Jala Group are partnering with bioprinting technology companies such as Poietis, Organovo, and CELLINK to bioprint complex human tissues like skin and hair follicles for cosmetic testing and research. These collaborations aim to advance product development by using bioprinted tissue models as a more complex and ethical alternative to traditional animal testing.
Tissue bioprinting could also be a game-changer in cancer drug discovery and development, with 3D bioprinted models offering the potential for personalized therapy, enhancing predictive accuracy of disease, and increasing the success of drug screening. Bioinks can also be produced using cancer cells obtained from patients or commercial cell banks. According to studies, the approach stands out as an ideal technique due to its affordability, flexibility, and high reproducibility.
Organoids
While cell cultures are tried and tested methods for screening drugs, how human cells behave in a dish is not necessarily how they behave in the body. One alternative could be miniature organs, called organoids. These 3D organoids are grown using stem cells, which, with the right cocktail of nutrients and treatments, can become the organ of choice.
Like with bioprinting, organoid research is still in its early stages, but there are several companies developing the technology. For example, HUB Organoids offers an approach to drug discovery and disease modeling using patient-derived organoids. These ‘mini-organs in a dish’ mimic human tissue biology, enabling predictive therapeutic insights and reducing drug attrition rates.
There is also an active academic community developing organoids. Earlier this year, Stanford Medicine researchers developed a way to create the first heart and liver organoids that generate their own blood vessels, possibly paving the way for organoid-based regenerative therapies. Meanwhile, Johns Hopkins University scientists also recently grew a novel whole-brain organoid, complete with neural tissues and rudimentary blood vessels, in an advancement that could usher in a new era of research into neuropsychiatric disorders.
However, one drawback of organoids is that they are still hard to manufacture reliably on a commercial scale. Another is that it is currently tricky to include a diverse set of cell types within the organoid, which is what one would find in real organs. There is work being done to overcome this, but there’s still a long way to go.
Organ-on-a-chip replacing animal testing
Organ-on-a-chip technology consists of growing cells inside tiny chips that mimic the structure and behavior of human organs. Because of the small size of the chips, researchers can test drugs more quickly and cheaply than in animals.
“The ultimate goal that researchers are working towards is a ‘human on a chip’; this tiny device would be able to replicate our heart, lungs, kidneys, liver, brain, and circulatory system, and could be used to predict the effects a drug would have on the body,” explained Alvarez.
By using human cells within a controlled, microfluidic environment, these “tissue chips” allow scientists to study disease, test new drugs, and understand organ-specific functions more accurately than traditional cell cultures or animal models. This approach holds promise for accelerating drug development, reducing the need for animal testing, and advancing personalized medicine
Organ-on-a-chip technology is advancing at a rapid rate. Valued at $159.48 million in 2024, the market size for the technology is predicted to hit around $3,242.34 million by 2034, according to a recent study published by Towards Healthcare.
Minimizing animal testing through silico modeling and AI technology
In silico modeling uses computer algorithms and models to simulate biological systems and predict how new drugs and chemicals will behave in the human body, providing a powerful alternative to animal testing by enabling virtual experiments and the analysis of vast datasets. These computational approaches help identify potential toxicities and effective treatments, leading to more efficient drug development and improved safety assessments.
In silico models work by integrating large datasets from various sources, including prior animal studies, in vitro experiments, and human clinical data. Complex algorithms and mathematical models are used to simulate human biology and the progression of diseases, and these simulations can subsequently predict how chemicals or drugs will interact with cells and tissues within the body, allowing scientists to assess potential effects without direct animal testing.
In fact, during the COVID-19 pandemic, researchers used in silico models to investigate how various vaccines fought the virus, and the results were remarkably consistent with those from human trials.
With the recent advancements in AI, in silico models are now becoming even more accurate and predictive. AI provides the advanced algorithms needed for complex in silico tools, enabling researchers to analyze vast datasets, generate synthetic data to create virtual cohorts, refine models, and make smarter decisions in the development process.
As well as the approaches mentioned above, there are several other exciting options being explored: Alvarez told Labiotech that virtual reality headsets are used to train surgeons, and explore a body’s potential reaction to a drug, and reconstructed human skin models, built from tissues donated following surgeries, and human corneal models made from human cells, are also being used to accurately assess the effect of a chemical on the skin or eye, respectively.
New technologies related to animal testing alternatives
- NOVASkin®: 3D Human Skin Models – NOVA University Lisbon
- A Brain Organoid Model that Better Represents the Structure of the Human Brain – University of Saskatchewan
- Lymphoid Tissue System Harnesses Ex Vivo Immune Reactions for Rapid Antibody Production and Immune Response Prediction – Georgia Institute of Technology
Could we really eradicate the need for animal testing in biotech?
Many animal tests already have alternative methods accepted by U.S. agencies that are ready to be used: The National Institutes of Health website lists a number of alternative test methods, which either replace or reduce the use of animals. Additionally, the EU Reference Laboratory for alternatives to animal testing (EURL ECVAM) also runs the Tracking System for Alternative methods towards Regulatory acceptance (TSAR) that tracks the stages methods have reached in terms of acceptance as a recognised test method for use in various sectors.
The phasing out of animal testing is not just important with regard to ethical considerations; many studies state that animal models are also resource-intensive, costly, time-consuming, and have limited predictivity for humans, with an overreliance on animal models resulting in many clinical trial failures and unsafe drugs reaching patients. A good example of this is in neurodegenerative disease research, such as Alzheimer’s, where many drugs have failed in clinical trials after showing promise in animal testing.
“One reason for this [why drugs fail despite promising preclinical results] is that animals do not naturally develop many of the diseases that affect humans, so researchers often have to artificially induce symptoms, which rarely replicates the human condition,” explained Alvarez. “Even tests on species considered ‘close’ to humans, like monkeys, have shown negligible predictive value. Our own research found that tests in dogs increase the probability of a new drug being free from harmful side effects in humans by just 2%, and in monkeys by only 0.4%. That’s not scientific rigor; it’s tradition standing in the way of science. These statistics make it clear that animals are poor models to study humans.”
So, why has it taken so long for us to begin the path toward phasing out animal testing in biotech and pharma?
“There are several reasons that tests on animals are still used despite the availability of non-animal methods, and in our view, many of the biggest barriers to replacing animal tests are not scientific – they are structural, regulatory, and rooted in outdated mindsets,” said Alvarez.
She explained that a key barrier is weak regulatory enforcement and unclear guidance. For example, in the UK and EU, it is illegal to conduct animal tests if non-animal methods exist, yet such tests may still occur due to inadequate oversight and uncertainty about how non-animal approaches can be used to meet legislative data requirements. Meanwhile, another major barrier is the lack of global harmonisation, whereby companies may be reluctant to adopt non-animal methods if the animal test is still required in other countries, making it more difficult to stop using them entirely for international markets.
There is also a significant hurdle in the way non-animal methods must often be validated separately for different products and regulatory sectors, even when the underlying science is well-established. “This kind of fragmentation slows progress and discourages innovation – especially when you consider that many traditional animal tests were never formally validated in the first place. It is a frustrating double standard that continues to hold science back,” stressed Alvarez.
The truth is that animal models are still seen by many as being crucial for scientific development. This means that, while new approach methodologies may reduce animal testing in the coming years, animals will still likely be used to validate the results before testing in humans, at least for the foreseeable future, until alternative approaches begin to form the cornerstone of biomedical testing – which, naturally, will take time.
Nevertheless, Alvarez is hopeful. “Far from hampering industry, the phase-out of animal testing can be a catalyst for innovation, in both the manufacture of products and the development of non-animal testing methods which can then be shared with other industries. The pharmaceutical industry is full of innovation, and with the right mix of transparency, leadership, and strategic collaboration, it can lead this transition. But that leadership must be active and visible if we want to see meaningful change.”
Organoids in cancer research: Paving the way for faster drug development across cancer indications
