What FDA's NAM Guidance Means for Pharmaceutical Development

On March 18, 2026, the FDA issued a draft guidance document outlining a validation framework for new approach methodologies used in drug development.¹ This move has direct implications for how nonclinical safety data are generated, assessed, and submitted across the industry.

The guidance describes general recommendations for validating new approach methodologies when nonclinical data is provided in support of a drug application.¹ These methodologies include complex in vitro systems, two-dimensional in vitro models, in chemico studies, and in silico approaches. For teams involved in preclinical program design, understanding this framework is increasingly important as regulatory expectations shift.

This development reflects a broader legislative and regulatory trajectory.¹ In 2022, Congress passed legislation clarifying that nonanimal alternatives can be used to support an investigational new drug application or a biosimilar biologics license application in lieu of animal studies. The guidance builds on that legislative foundation and aligns with the agency's Roadmap to Reducing Animal Testing in Preclinical Safety Studies, published in April 2025.

What Does the Validation Framework Require?

The guidance organizes its recommendations around four core features: context of use, human biological relevance, technical characterization, and fit-for-purpose assessment.¹ The context of use must clearly define the intended regulatory purpose of the methodology. Acceptable examples identified in the guidance include supporting dosage selection, addressing the mechanistic understanding of an adverse event seen in animals and/or humans, justifying not using an animal species because it does not add value to regulatory decision-making, and helping to support a weight of evidence approach and predicting risks typically not measured in humans.

Human biological relevance is another central pillar.¹ The guidance calls on sponsors to describe the physiological features being assessed, including the relevance of cell types used, species of origin, and how anatomical and physiological characteristics involved in toxicology findings may be mimicked in the platform. For a hepatotoxicity model, for instance, the guidance specifies that the model should contain the relevant cell types and biological features to recapitulate the hepatocellular physiology observed in vivo. For neurotoxicity assessments, the choice of neural cellular composition and cellular architecture may affect biological and functional baseline characteristics and should be carefully considered when selecting an appropriate model.

On technical characterization, sponsors are expected to document test method parameters including dosing frequency, substance preparation, detection instrumentation, and potential sources of assay variability.¹ Biological variability, including genetics and donor variability, must be described, and the selection of reference compounds such as positive and negative controls must be defined and justified. For platforms such as organ-on-a-chip devices, additional documentation is required around flow, shear stress, matrix properties, and evidence ruling out interactions between the test article and the platform itself.

Does a Methodology Need to Be Validated Before it can Be Used?

This is a question many development teams will have, and the guidance addresses it directly.¹ The agency states that for a new approach methodology to be considered for review in drug development, the test does not necessarily need to be validated. A fit-for-purpose methodology, even if not validated, may adequately address specific toxicological concerns.

Thw agency is clear that when a methodology is used, it is always in the context of the weight of evidence, considering the specific concerns about that product based on prior knowledge and any preclinical toxicological information provided.¹ The guidance distinguishes between validation, which establishes accuracy, reliability, and relevance for a specific context of use, and qualification, which is a separate determination under the agency's drug development tool program. Both can support regulatory review, but validation is described as critical to establishing the reliability of data for specific situations.

The fit-for-purpose standard is defined in terms of a methodology's contribution to regulatory decision-making.¹ A methodology may fulfill one of three drug development objectives: replacing or offering an alternative to traditional methods, filling a data gap where traditional models are unavailable or insufficient, or confirming and complementing findings from traditional methods. In practical terms, this gives development teams flexibility in how they position a methodology within a broader nonclinical package.

The agency has already accepted some methodologies under this framework. Certain approaches that evaluate eye irritation, skin irritation, and skin sensitization have been accepted as fit-for-purpose, including in vitro reconstructed human epidermis assays used to predict risk for human skin sensitization in place of the local lymph node assay in mice.

The agency encourages sponsors to consult with the applicable review division if there is uncertainty about the suitability of the method for regulatory use.¹ Especially when considering use of a nonanimal testing method believed to be suitable, adequate, and feasible for a proposed regulatory use. Early engagement is recommended, with interactions expected to focus on indication-, disease-, organ-, and endpoint-specific considerations.

How Does FDA's Broader Modernization Agenda Affect Drug Developers?

The agency's modernization push extends beyond methodology validation.² The FDA also launched a unified platform for analyzing adverse event reports, the FDA Adverse Event Monitoring System. The system consolidates what had previously been a patchwork of seven separate databases. The new system enables adverse event reports for drugs, biologics, vaccines, and cosmetics to be displayed in a single dashboard, with real-time publication replacing the prior quarterly release cycle. The agency estimates savings of approximately $120 million over five years. The shift toward real-time postmarket surveillance data represents another dimension of the agency's broader modernization agenda.

References

1. U.S. Food and Drug Administration, Center for Drug Evaluation and Research. General Considerations for the Use of New Approach Methodologies in Drug Development: Guidance for Industry. Draft guidance. March 2026. https://www.fda.gov/news-events/press-announcements/fda-releases-draft-guidance-alternatives-animal-testing-drug-development
2. U.S. Food and Drug Administration. FDA launches new Adverse Event Look-Up Tool [news release]. March 11, 2026. Accessed March 19, 2026. https://www.fda.gov/news-events/press-announcements/fda-launches-new-adverse-event-look-tool