Fifteen years of progress in transitioning from animal testing to New Approach Methodologies (NAMs)
Federal Agencies Coordinated
Human Skin Tests in Database
Years of Progress
Key Test Types Being Replaced
Fifteen years ago, a quiet revolution began in the world of toxicology. In 2010, the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) was already looking toward the future, recognizing that traditional animal testing approaches had significant scientific limitations.
While animal studies had contributed valuable insights for decades, scientists were increasingly aware that results from mice or rats didn't always translate well to humans. This realization sparked a transformative journey to reinvent how we evaluate chemical safety—a journey that would accelerate the development of methods that are not only more human-relevant but often faster, cheaper, and more ethical.
Today, we stand at a pivotal moment where technological advances are fundamentally changing toxicology. Through ICCVAM's coordination across 17 federal agencies, science is shifting from traditional animal models to what experts call New Approach Methodologies (NAMs)—sophisticated tools ranging from miniature human organs grown in labs to advanced computer simulations that can predict toxicity with remarkable accuracy.
This article explores how ICCVAM's work over the past 15 years is reshaping safety testing, highlighting the breakthroughs already making a difference and the exciting future ahead where human biology, not animal models, sits at the center of toxicological research.
To understand the significance of ICCVAM's work, we must first understand its role. Established as a permanent committee of the U.S. government, ICCVAM doesn't conduct research itself but coordinates activities across 17 federal regulatory and research agencies, including the FDA, EPA, and NIH 2 . This cross-agency coordination is crucial because it ensures that new testing methods developed by researchers can be accepted and implemented consistently across the government.
ICCVAM coordinates activities across multiple federal agencies including FDA, EPA, and NIH to ensure consistent implementation of new testing methods.
Supported by NICEATM (scientific support) and SACATM (external advisory group) with experts from academia, industry, and animal welfare organizations 2 .
Central to ICCVAM's mission is the "3Rs" framework—Replace, Reduce, and Refine animal use in testing .
ICCVAM is supported by two key partners: NICEATM (NTP Interagency Center for the Evaluation of Alternative Toxicological Methods), which provides scientific and administrative support, and SACATM (Scientific Advisory Committee for Alternative Test Methods), an external advisory group that includes experts from academia, industry, and animal welfare organizations 2 . Together, this structure ensures that new methods are rigorously evaluated and that multiple perspectives inform the development and implementation of alternatives.
Central to ICCVAM's mission is the "3Rs" framework—Replace, Reduce, and Refine animal use in testing . This means replacing animal models with non-animal systems when possible, reducing the number of animals required for testing to the minimum necessary, and refining procedures to eliminate pain or distress while enhancing animal well-being. This framework guides all of ICCVAM's activities and represents a balanced approach that acknowledges both scientific progress and ethical responsibility.
The term "New Approach Methodologies" encompasses a diverse toolkit of advanced scientific techniques that offer more human-relevant ways to study chemical effects.
Unlike traditional animal testing, these methods focus directly on human biology, potentially providing more accurate predictions of how substances will affect people. The NAMs landscape includes three broad categories of innovative approaches :
| Category | Description | Examples |
|---|---|---|
| In chemico | Experiments performed on biological molecules outside of cells | Testing interactions between chemicals and proteins or DNA |
| In silico | Experiments performed using computer simulations | Artificial intelligence, machine learning, mathematical modeling of biological processes |
| In vitro | Experiments performed on cells outside the body | Organ-on-chip devices, organoids (mini-organs), high-throughput cell screening |
Microfluidic cell culture devices that simulate the activities, mechanics, and physiological response of entire organs and organ systems.
Three-dimensional, tissue-like structures grown from stem cells that closely replicate the complexity of human organs .
Some of the most exciting NAMs include organ-on-chip devices that mimic human organ systems, organoids (three-dimensional, tissue-like structures grown from stem cells that closely replicate the complexity of human organs), and sophisticated computational models that can predict toxicity by recognizing patterns in chemical data . These systems can incorporate human cells, providing direct insight into human biology without the species extrapolation challenges inherent in animal testing.
What makes NAMs particularly powerful is their ability to model human diversity. Traditional animal testing typically uses genetically identical animals, but NAMs can incorporate cells from people with different genetic backgrounds, helping researchers understand how various human populations might respond differently to chemical exposures . This capability is particularly important for addressing environmental health disparities, as some communities experience higher levels of exposure or susceptibility to toxic chemicals.
One of the most successful implementations of NAMs has been in the area of skin sensitization testing—determining whether a chemical might cause allergic reactions on skin.
This application perfectly illustrates how understanding biological mechanisms, combined with human-relevant data, can create alternatives that may outperform traditional animal tests.
The breakthrough in skin sensitization testing came from integrating multiple approaches. Researchers recognized that the biological process of skin sensitization was well-understood, which allowed them to identify key steps in the pathway that could be measured without using animals 2 .
The National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) played a crucial role by collecting, curating, and annotating data from over 2,000 human predictive patch tests (HPPT) to create a comprehensive database 2 . This human data became the gold standard against which new methods could be evaluated.
The research team developed and validated several complementary approaches:
The SARA-ICE model is particularly noteworthy—it's a Bayesian statistical model that estimates the point of departure for skin sensitization using data from one or more test methods, whether they use human cells, mouse cells, or existing information 2 . This flexible approach allows scientists to combine the most relevant data for their specific needs while maintaining scientific rigor.
The validation of these alternative methods for skin sensitization has had tangible impacts. The Organisation for Economic Co-operation and Development (OECD), which sets international testing standards, included the SARA-ICE model in its Test Guideline 497: Defined Approaches on Skin Sensitization 2 . This international acceptance means that data generated using these methods can be used for regulatory decisions across multiple countries, reducing redundant testing and accelerating the adoption of alternatives.
This success with skin sensitization testing has created a roadmap for other areas of toxicology. Similar approaches are now being applied to cardiovascular toxicity, carcinogenesis, and developmental neurotoxicity 2 . The latter is particularly important because traditional animal tests for developmental neurotoxicity are time-consuming, expensive, and use large numbers of animals. The OECD's DNT/IATA framework represents a similar shift toward integrating multiple types of data to assess this complex endpoint.
| Test Type | Traditional Animal Use | NAM-based Alternatives | Reduction Potential |
|---|---|---|---|
| Acute Dermal Toxicity | High | Available |
|
| Acute Oral Toxicity | High | Available |
|
| Acute Inhalation Toxicity | High | Available |
|
| Skin Sensitization | High | Multiple alternatives available |
|
| Eye Irritation | High | Available |
|
| Skin Irritation | High | Available |
|
The development of alternatives isn't happening in isolation—federal agencies have created strategic roadmaps to accelerate their implementation.
Focuses on specific applications where animal models have proven particularly limited, such as the safety testing of monoclonal antibody-based drugs 2 .
In this area, animal studies often fail to predict human responses due to immunogenicity issues and human-specific toxicity mechanisms. Since the biological mechanisms are comparatively well-understood and alternative approaches perform well, this represents an ideal target for implementing NAMs.
Represents a major investment in the infrastructure needed to support NAMs 2 . This program includes:
This infrastructure is critical because one of the biggest challenges in implementing NAMs has been the lack of standardized, well-characterized methods that regulatory reviewers can trust. By addressing these validation and qualification hurdles systematically, Complement-ARIE aims to build the confidence needed for widespread adoption.
The shift toward NAMs requires new tools and resources. Fortunately, several key resources have been developed to support researchers and regulators in this transition.
| Resource | Type | Function | Access |
|---|---|---|---|
| ICE (Integrated Chemical Environment) | Data Resource | Provides data, models, and tools to develop and evaluate NAMs | Online portal |
| CAMERA | Database | Collates information on validated alternative methods and validation data | Online resource |
| HPPT Database | Specialized Database | Contains human skin sensitization data from >2,000 tests | Available through ICE |
| Tox21BodyMap | Computational Tool | Predicts which human organs may be affected by a chemical | Online tool |
| ChemMaps | Web Tool | Explores environmental chemicals and predicts risk | Public website |
These resources collectively address one of the critical needs in the field: access to high-quality, curated data. As Warren Casey (NIEHS), Helena Hoegberg (NICEATM), and other experts have emphasized, such data are essential for effective NAMs validation 2 .
Well-structured data with effective annotation also becomes increasingly important as researchers begin to apply artificial intelligence and machine learning approaches to toxicology.
The validation process itself is evolving to accommodate these new methodologies. The ICCVAM Validation Workgroup has published a report on "Validation, Qualification, and Regulatory Acceptance of New Approach Methodologies," and there are ongoing international efforts to update the OECD's Guidance Document on the Validation and International Acceptance of New or Updated Test Methods (GD34) 2 .
These updated frameworks recognize that validating a computational model or an organ-on-chip device requires different approaches than validating a simple animal test.
Fifteen years into its reinvention, ICCVAM has made remarkable progress in shifting toxicology toward more human-relevant methods.
From the successful implementation of alternatives for skin sensitization testing to the development of comprehensive roadmaps and infrastructure, the pieces are falling into place for a fundamental transformation of safety assessment. What began as a coordination effort among federal agencies has grown into a broader movement that includes researchers, regulatory agencies, industry, and animal welfare advocates—all working toward the common goal of better, more human-relevant science.
Need to evolve further to efficiently handle the diversity of NAMs
Must continue to grow as these methods prove their value 2
Between NAMs developers and regulators remains crucial
The vision for the future is clear: a toxicological testing paradigm where human biology, enabled by advanced technologies, provides the primary basis for understanding chemical safety. As this transition continues, ICCVAM's coordinating role will remain essential. The next 15 years will likely see an acceleration of this trend, with NAMs becoming increasingly sophisticated and integrated into regulatory decision-making. This represents not just a technical shift in testing methods, but a fundamental evolution in how we protect human health from chemical hazards—one grounded in the most relevant biology possible: our own.