For decades, animal testing has been the default method for validating drug safety and efficacy in biomedical research. But a convergence of technological advances and regulatory shifts is accelerating a fundamental transition away from animal models.
The shift began in earnest with innovations like the lung-on-a-chip, developed 17 years ago at Harvard University’s Wyss Institute for Biologically Inspired Engineering. The device—smaller than a USB stick—uses a polymer slab with narrow channels lined with human cells. When air is pumped through adjacent chambers, the tissue rhythmically expands and contracts, simulating breathing. When exposed to inflammatory proteins, bacteria, and nanoparticles, the artificial lung responded similarly to living lungs, demonstrating that lab-grown tissues could predict biological responses more accurately than static cultures.
These alternatives, collectively known as NAMs (new approach methodologies, novel alternative methods, or nonanimal methods), have evolved substantially. Beyond organ-on-a-chip systems, researchers now develop organoids that more closely mimic organ structure and function, multi-organ systems linking as many as 10 organs together, and computational simulations supported by artificial intelligence tools.
The regulatory landscape shifted significantly in late 2022 when the FDA Modernization Act 2.0 passed into law, explicitly authorizing NAMs in preclinical studies required before drugs enter human trials. Previous regulations had mandated animal testing. In 2025, the FDA pledged to “make animal studies the exception rather than the norm” for drug safety testing.
The change reflects both scientific and practical concerns about animal models. An estimated 92 percent of drugs entering U.S. clinical trials fail to reach market, often because they prove ineffective or unsafe in ways animal experiments did not predict. Failure rates are even higher for heart disease, cancer, and neurological conditions.
Despite technological readiness, widespread adoption faces obstacles. According to Thomas Hartung, director of the Center for Alternatives to Animal Testing at Johns Hopkins University, the primary challenge is not technical but cultural: “This transition process is much more complicated than you would think. It is more about change management than it is about the technology.” Validating NAMs requires standardizing systems, conducting head-to-head comparisons with animal experiments, and changing policy and training practices across the biomedical research community.
Key facts
- The FDA Modernization Act 2.0, passed in late 2022, explicitly authorized alternatives to animal testing in preclinical drug studies, reversing previous regulations that mandated animal testing.
- An estimated 92 percent of drugs entering U.S. clinical trials fail to reach market, often because animal models failed to predict their ineffectiveness or safety issues in humans.
- Organ-on-a-chip systems, organoids, and multi-organ platforms can link as many as 10 organs together to better recapitulate human physiology than traditional animal models.
- Adoption of alternatives to animal testing is hindered primarily by cultural and regulatory factors rather than technical limitations, according to toxicology experts.