Using NAMs Where They Add Real Regulatory Value
- Entry to Regulatory
- May 26
- 11 min read
The Shift That Is Redefining Nonclinical Regulatory Science
For decades, the nonclinical safety assessment of medicines followed a well-worn path: animal studies, conducted to prescribed protocols, submitted in dossiers shaped by guidelines written largely in the 1980s and 1990s. That path is not disappearing — but it is being fundamentally disrupted by the rise of New Approach Methodologies (NAMs): a broad family of non-animal, human-relevant tools that are now moving from scientific promise to regulatory reality.
NAMs encompass a diverse and rapidly expanding toolkit — in vitro cell-based assays, organ-on-a-chip systems (microphysiological systems), organoids, computational models (QSAR, PBPK), transcriptomics, artificial intelligence, and integrated approaches to testing and assessment (IATA). What unites them is a shared ambition: to better predict human biology and toxicology than traditional animal studies, while simultaneously reducing or replacing animal use in drug development.
The regulatory landscape around NAMs is shifting fast, and for regulatory affairs professionals, that shift creates both challenge and opportunity in equal measure. Understanding where NAMs genuinely add regulatory value — and where they do not yet deliver it — is now a core competency for anyone working in nonclinical regulatory strategy.
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What Are NAMs — And Why Are Regulators Taking Them Seriously Now?
The term "New Approach Methodologies" was coined to capture the breadth of non-animal methods being developed for toxicological and pharmacological assessment. In a regulatory context, a NAM has value when it can inform a safety or efficacy decision that would otherwise require an animal study — or when it can add mechanistic insight that an animal study simply cannot provide.
Historically, the challenge was not scientific scepticism about NAMs' potential, but a practical one: regulatory acceptance. Regulators and industry both needed validated, standardised methods with sufficient confidence to replace established animal study protocols — protocols enshrined in ICH, OECD, and national guidelines that carry legal weight.
That barrier has not vanished — but it is lower than at any point in history. Several forces are accelerating NAM integration into the regulatory mainstream:
1. Legislative Change: The FDA Modernization Act 2.0
In December 2022, the US FDA Modernization Act 2.0 was signed into law, removing the longstanding statutory requirement that all drugs must undergo animal testing before human clinical trials. This was a landmark shift. It did not mandate NAM use — but it created the legal space for companies to propose NAM-based nonclinical packages to the FDA, without animal data, where the science supports it.
The FDA swiftly responded with operational framework. In 2025, the agency declared it an "implementation year" for NAMs, releasing draft guidance titled "General Considerations for the Use of New Approach Methodologies in Drug Development" — the first comprehensive FDA roadmap for how to use NAMs in submissions. Simultaneously, the FDA's ISTAND (Innovative Science and Technology Approaches for New Drugs) program — which allows qualification of novel methodologies — was formalised into a permanent framework for industry engagement.
2. The EMA's Evolving Stance
The European Medicines Agency has been developing its position on NAMs through a series of reflection papers, qualification opinions, and scientific advice outputs. The EMA's overarching direction is toward "3Rs integration" (Replace, Reduce, Refine animal use) embedded within the regulatory review process — not as a box-ticking exercise, but as a scientifically grounded shift in how nonclinical packages are evaluated.
The EMA now actively encourages sponsors to discuss NAM-based approaches during Scientific Advice procedures, and qualification opinions for specific tools (including microphysiological systems for organ toxicity) have been issued. The European Partnership for Alternative Approaches to Animal Testing (EPAA) continues to drive collaboration between industry, regulators, and research institutions across EU member states.
3. The UK: A Post-Brexit Policy Window
Post-Brexit, the MHRA has positioned itself as an innovator-friendly regulator willing to engage with NAMs proactively. The UK government introduced dedicated funding for alternative methods in 2025 as part of its life sciences strategy, and the MHRA's Innovation Office offers early dialogue for companies wanting to deploy NAMs in novel ways. For companies navigating both EU and UK regulatory pathways, understanding how each agency's NAM stance differs — and where alignment remains — is increasingly important.
Where NAMs Already Add Proven Regulatory Value
The most important question for regulatory teams is not whether NAMs are theoretically valuable — it is where they are accepted by regulators today, in what contexts, and under what conditions. The picture is clearer than many appreciate.
Skin Irritation and Corrosion
Reconstructed human epidermis (RHE) models — most prominently EpiDerm™ and SkinEthic™ — are now fully accepted by OECD guidelines (TG 431, 439) and integrated into regulatory submissions globally. These in vitro tests have replaced rabbit skin irritation studies as the default approach across cosmetics and are increasingly accepted in pharmaceuticals and chemicals regulation. This is NAMs working exactly as intended: a validated, standardised, reproducible method with clear mechanistic relevance that has supplanted an animal study of questionable human relevance.
Eye Irritation and Ocular Toxicity
The replacement of the Draize rabbit eye test has been a long-standing goal of the 3Rs community. Multiple OECD-validated NAM approaches now exist — including the Short Time Exposure (STE) test, Reconstructed Human Cornea-like Epithelium (RhCE) models, and the Bovine Corneal Opacity and Permeability (BCOP) assay — each addressing specific parts of the ocular irritation assessment. These are not yet universal replacements for all endpoints, but within defined chemical domains and product types, they provide regulatory-grade evidence. Regulatory professionals need to understand both the scope and the limitations of each method.
Phototoxicity
The 3T3 Neutral Red Uptake (3T3 NRU) phototoxicity assay (OECD TG 432) is a well-established NAM that has functionally replaced in vivo phototoxicity studies for most pharmaceutical and cosmetic applications. This is a mature example of a NAM completing the full validation-to-guideline journey and becoming regulatory standard practice.
Genotoxicity
The genotoxicity testing battery has long included in vitro assays — but the historical challenge was high false-positive rates that triggered unnecessary in vivo follow-up. Next-generation genotoxicity NAMs, including 3D reconstructed tissue micronucleus assays and high-content imaging approaches, are now being qualified to deliver higher specificity and reduce confirmatory in vivo studies. The ICH S2(R1) guideline already permits some flexibility in in vivo follow-up — a regulatory handle that sophisticated teams use strategically.
Computational Models: QSAR and PBPK
Quantitative Structure-Activity Relationship (QSAR) models are now routinely used in regulatory submissions — particularly for impurities and degradation products assessed under ICH M7 (mutagenic impurities) and ICH Q3A/B. Regulators accept QSAR-based read-across for setting acceptable limits on impurities where experimental data is unavailable, provided models are validated and transparent.
Physiologically-Based Pharmacokinetic (PBPK) models have become a genuine regulatory tool — accepted by the FDA, EMA, and MHRA for informing dosing decisions in special populations (paediatrics, renal impairment, hepatic impairment), drug-drug interaction predictions, and bioequivalence assessments. PBPK model submission packages now appear routinely in marketing applications. This is perhaps the most commercially mature NAM category in pharmaceutical regulation today.
Where NAMs Are Developing — But Not Yet Delivering Full Regulatory Value
Honest regulatory assessment requires acknowledging where NAMs are promising but not yet ready to replace established methods in submissions.
Organ-on-a-Chip and Microphysiological Systems
Organ-on-a-chip (OoC) platforms — microfluidic devices containing human cells arranged to mimic organ physiology — are among the most exciting NAM technologies. Liver-on-a-chip, kidney-on-a-chip, lung-on-a-chip, and multi-organ "body-on-a-chip" platforms have demonstrated remarkable predictive capacity in research settings, including for drug-induced organ toxicity that animal models routinely miss.
However, regulatory qualification is still in progress. The FDA's 2025 Validation & Qualification Network (VQN) was established specifically to build the standardisation and cross-site reproducibility evidence needed for regulatory-grade confidence. The GAO's 2025 Technology Assessment validated OoC potential while also cataloguing the remaining barriers: inconsistent manufacturing, limited assay standardisation, and a thin evidence base from prospective studies that compare OoC predictions against known clinical outcomes.
For regulatory affairs professionals, the practical position is this: OoC data can be included in submissions as supporting or mechanistic information, but cannot yet replace standard repeated-dose toxicity studies. That will change — but the timeline is measured in years, not months.
Organoids and 3D Cell Culture
Patient-derived organoids — three-dimensional, self-organising tissue structures that recapitulate organ biology with striking fidelity — are generating enormous scientific excitement. For oncology drug development, patient-derived tumour organoids are already influencing clinical trial design decisions. For toxicology, intestinal, hepatic, and renal organoids are demonstrating capacity to detect toxicity signals that 2D cell culture misses.
The regulatory integration pathway for organoids is less advanced than for OoC, largely because standardisation across laboratories remains an unsolved challenge. The NIH Standardized Organoid Modeling Center, launched in 2025, is specifically designed to address this barrier. Watch this space — organoid qualification is coming.
AI and Machine Learning in Toxicity Prediction
Artificial intelligence and machine learning tools are being applied across every dimension of nonclinical safety assessment — from read-across toxicity prediction to adverse outcome pathway (AOP) mapping to image analysis of histopathology slides. The FDA and EMA have both issued statements of intent around AI use in regulatory submissions, and guidance is developing.
The current regulatory reality is nuanced: AI predictions can support regulatory decisions as part of an IATA — but rarely as standalone evidence. Transparency, explainability, and model validation are the keys to regulatory acceptance, and these remain active areas of development for most AI toxicology tools.
The IATA Framework: How to Integrate NAMs Strategically
For regulatory professionals, the most practically important concept in NAM deployment is Integrated Approaches to Testing and Assessment (IATA) — the structured combination of existing data, in silico predictions, in vitro data, and targeted in vivo studies into a coherent weight-of-evidence argument.
IATA is not a single method — it is a decision framework. It allows companies to build regulatory cases from multiple NAMs and other data sources without needing any single NAM to be a complete, validated replacement for an animal study. The OECD has published guidance on IATA for multiple endpoints, and regulators increasingly expect to see this kind of structured argumentation in submissions.
Key principles of a strong IATA regulatory argument:
- Define the assessment question clearly — what hazard endpoint are you addressing?
- Inventory existing data — literature, structural analogues, prior studies
- Select mechanistically relevant NAMs — tools that address the specific biology of the endpoint
- Articulate the weight of evidence — how do the individual lines of evidence combine?
- Acknowledge uncertainty — regulators appreciate transparency about what the data does and does not show
- Engage regulators early — via Scientific Advice (EMA), Pre-IND meetings (FDA), or Innovation Office (MHRA)
What This Means for Regulatory Affairs Professionals: Roles, Skills, and Careers
The NAM revolution is not just a scientific development — it is a career development opportunity. The integration of NAMs into regulatory submissions creates demand for a new type of regulatory professional: one who bridges deep regulatory knowledge with understanding of emerging science.
High-Demand Roles at the NAMs/Regulatory Interface
Regulatory Toxicologist - Designing nonclinical packages using NAM-based strategies
Computational Toxicology Specialist - QSAR/PBPK modelling for regulatory submissions
Regulatory Intelligence Analyst- Tracking evolving NAM guidelines and agency positions
Nonclinical Regulatory Affairs Manager- Integrating NAMs into CTD Module 4 strategy |
Scientific Adviser (IATA) - Building weight-of-evidence regulatory arguments
Regulatory CMC/Toxicology Consultant - Supporting biotech/pharma companies adopting NAMs
Skills That Employers Are Prioritising
- Understanding of ICH nonclinical guidelines (S1–S11 series)
- Familiarity with OECD test guidelines and their NAM alternatives
- QSAR and read-across principles and tools (e.g., DEREK Nexus, Toxtree, VEGA)
- PBPK model interpretation and regulatory submission conventions
- Weight-of-evidence argumentation and IATA structuring
- FDA, EMA, and MHRA NAM guidance literacy
- Cross-functional communication — translating complex science for regulatory committees
The Road Ahead: Five Trends That Will Define NAMs in Regulatory Practice
1. Mandatory reporting, voluntary adoption — but increasing regulatory expectation
Regulators are not yet mandating NAMs, but the direction of travel is unmistakable. Companies that are not developing NAM capabilities now will face competitive disadvantage as regulatory expectations evolve.
2. 3Rs becoming a submission quality marker
Both the FDA and EMA are beginning to view a well-constructed, NAM-informed nonclinical strategy as a signal of scientific sophistication — something that reflects well on a development programme. Conversely, unconsidered, default-mode animal study programmes may attract scrutiny.
3. Harmonisation through ICH
ICH is actively revising nonclinical guidelines to accommodate NAMs. The revision of ICH S1 (carcinogenicity testing) has already reduced in vivo study requirements for many pharmaceutical candidates. Further revisions are in progress across the S-series.
4. The biologics and ATMPs intersection
Advanced Therapy Medicinal Products (ATMPs) — gene therapies, cell therapies, tissue-engineered products — are often poorly served by traditional animal testing. NAMs, particularly organoids and patient-derived microphysiological systems, may offer far more relevant safety assessment for ATMPs than anything rodent models can provide. This is a frontier where NAM regulatory strategy and biologics expertise will converge.
5. Digital regulatory submissions
As structured regulatory data formats evolve, the integration of computational NAM outputs (QSAR predictions, PBPK model outputs) into electronic submission formats is becoming a practical capability that regulatory affairs teams need to master.
Conclusion: Precision Over Protocol
The most important lesson from the rise of NAMs is not that animal testing is over — it is that fit-for-purpose nonclinical strategy matters more than ever. The regulatory professional of 2026 and beyond needs to understand which tools are validated for which endpoints, what regulators will accept and under what conditions, and how to construct a scientifically coherent, transparent regulatory argument from a mixed portfolio of evidence.
That expertise does not emerge from reading guidelines alone. It comes from understanding the science, the regulatory frameworks, and how to apply both in real-world submissions — exactly the kind of practical, applied knowledge that determines who gets hired and who delivers value from day one on the job.
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The regulatory affairs field is evolving at pace. NAMs, biologics, digital submissions, global harmonisation — the professionals who will thrive are those who build robust, practical foundations in regulatory science now, not those who are trying to catch up later.
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About the Author: Rabiea is an Honorary Associate Professor at UCL, former MHRA Health Authority reviewer, and CEO of Entry to Regulatory and Advanced Regulatory Consulting. After transitioning from retail pharmacy to regulatory affairs, she has dedicated her career to helping others make the same successful career change. Connect with her on LinkedIn for the latest regulatory affairs insights and career advice.
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