More than 90 percent of drugs that pass animal testing go on to fail in human trials. That single statistic has haunted drug development for decades, and it’s a large part of why UK scientists are now betting on a fundamentally different approach.
Researchers at a new Medical Research Council-funded hub in Cambridge will grow miniature human organs, known as organoids, directly from NHS patient cells. The goal is to create a standardised library of these lab-grown tissues that academics and pharmaceutical companies can use to test drugs on human biology from the start, rather than relying on animal models that may not reflect how human disease actually behaves.
What organoids are, and why they matter now
Organoids are tiny clusters of human cells, often smaller than a millimetre, that can replicate key features of full-sized organs. Researchers have been growing them for more than a decade, but this programme represents a significant scaling up. Scientists plan to develop organoids covering a range of tissue types, from beating clusters of heart cells to electrically active brain tissue, as well as tumour models for cancer research.
Matthias Zilbauer, clinical professor of paediatric gastroenterology at the Cambridge Stem Cell Institute, was direct about the expected impact. “It’s going to have a major impact on the numbers of animals used and the way we develop new drugs in the future,” he said. He also acknowledged the limits: “We’re not saying there won’t be any animal use in the near or foreseeable future, because there are still certain issues that cannot be tested in these new models, but the reduction is very real.”
The clinical case for human tissue over animal models
The argument is not just ethical. It’s scientific. Many human diseases either don’t appear in animals or present differently because human and animal biology diverge in ways that matter. “A mouse cannot tell us which treatments work, and in what patients,” Zilbauer said. Organoids grown from diseased human tissue can help researchers understand whether a drug works across a broad patient population or only in specific subgroups, which is exactly the kind of insight that animal models struggle to provide.
Zilbauer’s team will begin with organoids for inflammatory bowel diseases including ulcerative colitis and Crohn’s disease. Other groups at the hub will focus on brain organoids for neurological conditions and tumour models for oncology.
Broader policy push and industry investment
The Cambridge hub sits within a wider government strategy, developed under Keir Starmer’s administration, to accelerate the reduction of animal testing in the UK. The strategy draws on what regulators call new approach methodologies, or NAMs. These include:
- Organoids grown from patient tissue
- Organ-on-a-chip systems that mimic physiological conditions
- Artificial intelligence tools for biological data modelling
There were 2.54 million animal testing procedures in Britain last year, down 3.8 percent on the previous year. US and European medicines regulators now actively encourage alternatives where available.
A separate £2m from Innovate UK has gone to nine projects targeting safety testing, including work by company VivoSphere, which grows heart cells in tiny gel spheres. Traditional cardiac safety tests can involve between 50 and 100 animals. VivoSphere’s approach is designed to catch toxic compounds earlier, before they ever reach that stage. As the company’s chief technology officer Yuan Tian put it: “If something is going to fail, there’s a lower risk for the animals and also for the patients.”
A path toward more personalised medicine
Beyond reducing animal use, the longer-term clinical promise here is personalisation. Because organoids can be grown from individual patient cells, they carry that patient’s specific disease characteristics. That opens the possibility of testing which drug, at which dose, is most likely to work for a specific person rather than for an average population. So this isn’t only a story about animal welfare or regulatory compliance. It’s about whether we can build drug development tools that are genuinely fit for the complexity of human disease.