Animal Models vs. NAMs: Understanding Modern Preclinical Research

Animal models have been the basis of preclinical drug development for decades, offering a platform to evaluate drug efficacy, pharmacokinetics and safety prior to clinical assessment. Yet, despite decades of success, animal studies often fail to accurately predict human responses because of basic biological differences between species. Consequently, researchers are increasingly relying on New Approach Methodologies (NAMs) – a broad spectrum of human-relevant technologies that complement and enhance traditional preclinical testing.

The change is mainly due to the persistent translational gap in drug development. Many drug candidates show promising results in laboratory animals, but more than 90% of them fail in human clinical trials, often due to insufficient efficacy or unexpected toxicity. These challenges have increased international interest in developing more predictive, human-centered experimental models.

NAMs are not a single technology, but a broad ecosystem of in vitro, in silico and in chemico approaches such as organoids, organ-on-chip systems, advanced computational modelling and artificial intelligence. These technologies are transforming modern preclinical research by providing insights complementary to human biology.

Table 1. Animal models vs. NAMs: a quick comparison

The Structural Comparison: Animal Models vs. NAMs

To understand this paradigm shift, we must look at how these two methodologies approach the human body.

Traditional Animal Models

Animal testing is based on the principle of whole-organism systemic biology. A live mammal gives researchers a chance to see how a drug behaves in the complicated web of connections — how the gut absorbs it, the liver metabolizes it and the kidneys excrete it.

But animal models have an unavoidable problem: genetic and physiological differences between species. Evolution is complicated. A drug that works in an inbred lab mouse often fails in a human patient because our metabolic pathways, gene expressions and cellular receptors are fundamentally different.

Why Animal Models Remain Valuable

The development of NAMs is rapidly progressing, but animal models are still an indispensable part of biomedical research. Their main advantage is that they can capture interactions between multiple organs, immune responses, metabolism, endocrine regulation and long-term physiological changes in a living organism.

Animal models have been the engine behind numerous medical advances, and continue to be a crucial part of many areas of preclinical research. They are increasingly part of a wider evidence generation strategy alongside emerging human-relevant technologies rather than being replaced.

The NAMs Framework

New Approach Methodologies (NAMs) are not one single experimental platform but a diverse ecosystem of technologies that can be used to generate human relevant biological data. These approaches can be classified in several complementary groups:

1. Human Cell-Based Models (In Vitro)

Human primary cells, induced pluripotent stem cell (iPSC)-derived cells, 3D spheroids, and organoids enable researchers to study disease mechanisms, drug efficacy, and toxicity using human-derived biological systems.

2. Microphysiological Systems (MPS)

Organ-on-chip and multi-organ-chip platforms recreate key aspects of tissue architecture, mechanical forces, fluid flow, and inter-organ communication, providing more physiologically relevant models than conventional cell culture.

3. Computational Models (In Silico)

Artificial intelligence, machine learning, physiologically based pharmacokinetic (PBPK) modeling, and quantitative structure–activity relationship (QSAR) models predict drug behavior, toxicity, and efficacy using computational approaches.

4. In Chemico Assays

These assays evaluate the intrinsic chemical reactivity of compounds, particularly for toxicity endpoints such as skin sensitization, without relying on living cells or animals.

By focusing entirely on human cells and human data, NAMs eliminate the biological guesswork.

The Core NAMs Technological Pillars

The power of NAMs lies in their ability to replicate the mechanics of human biology without using a living animal. This is achieved through three revolutionary technology pillars:

1. Microphysiological Systems (MPS) / Organs-on-Chips

In the past, cell culture meant growing cells flat in a plastic dish, which looked nothing like the human body. MPS changes this by introducing microfluidics—tiny channels etched into a silicone chip. By pumping fluids through these channels, scientists can grow human cells while mimicking the mechanical shear stress and blood flow. For example, a "lung-on-a-chip" can actually expand and contract like a real lung to simulate breathing, enabling researchers to watch exactly how human lung tissue responds to inhaled drugs or toxins.

Recent advances have also made it possible to have multi-organ chips, where interconnected liver, heart, gut or kidney tissues are connected via microfluidic circulation. These integrated platforms provide valuable insights in systemic drug responses that are difficult to capture using isolated cell cultures.

2. Three-Dimensional (3D) Organoids

Organoids are lab-grown, living mini-organs that self-organize. You take human stem cells, either embryonic or reprogrammed from adult skin cells, and you put them in some sort of nutrient broth. The cells naturally cluster and differentiate. They grow into tiny 3D structures that mimic the architecture and genetic profiles of real human organs like mini-brains, mini-livers or mini-kidneys. This allows scientists to study complex tissue interactions in ways that flat 2D cell cultures never could.

Patient-derived organoids also retain the genetic characteristics and disease heterogeneity of individual patients and are thus valuable tools for precision medicine, biomarker discovery and personalized drug screening.

3. In Silico Systems & Artificial Intelligence

The digital pillar of NAMs relies on the explosion of big data and computational power. Artificial intelligence (AI) and machine learning algorithms can be employed by computational biologists to model complicated molecular interactions. These software systems can analyse the chemical structure of a new molecule and forecast its potential toxicity or effectiveness in seconds. Researchers can remove dangerous compounds before they ever arrive in a physical lab by doing virtual clinical trials on digital human models.

FAQ

Conclusion

Animal Models and a New Paradigm Methodologies are often characterized as competing technologies, but are in fact complementary in the context of today's biomedical research. Animal models are still useful for understanding complex whole body physiology, while NAMs are increasingly providing human relevant platforms to interrogate disease mechanisms, predict drug responses and improve translational success.

Emerging technologies such as organoids, organ-on-chip and artificial intelligence are not just replacing existing methods but are broadening the scientific toolbox that researchers have at their disposal and will continue to evolve and reshape the future of preclinical research.

In our next article we'll step back from the technologies themselves and turn to the practical questions that researchers ask themselves every day: When to use animal models? When should you choose NAM? How can such approaches be incorporated into the contemporary drug development pipelines while fulfilling regulatory expectations?

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