FDA Issues Draft Guidance to Validate Non-Animal Testing Methods in Drug Development

The FDA has released a draft guidance outlining how drug developers can validate new approach methodologies (NAMs) as alternatives to animal testing in preclinical drug development. The guidance, issued by the Center for Drug Evaluation and Research (CDER), provides a framework for establishing the scientific reliability of these methods when submitted in support of a drug application.¹

The move represents a significant step in the agency's broader effort to reduce reliance on animal models, which FDA leaders have increasingly characterized as poor predictors of human response. The draft guidance arrives roughly a year after FDA published its Roadmap to Reducing Animal Testing in Preclinical Safety Studies, and follows December 2025 draft guidance addressing the reduction of non-human primate testing for certain monoclonal antibodies.

"Technological advances are allowing us to move beyond animal testing in drug development, which has a poor track record of predicting safety and efficacy in humans," said FDA Commissioner Marty Makary, M.D., M.P.H. "This guidance will facilitate the adoption of modern alternatives to animal testing in regulatory submissions."

NAMs encompass a broad range of methods, including complex and two-dimensional in vitro laboratory studies, three-dimensional models such as organoids and organs-on-chips, in silico computer simulations, chemical reactivity studies, and research using phylogenetically lower organisms such as zebrafish. The guidance notes that several validated NAMs have already demonstrated stronger performance than traditional animal models in predicting human drug responses.

A validation framework for regulatory submissions

For clinical trial sponsors, the practical significance of the guidance lies in how it structures the path to regulatory acceptance. Under existing regulations, sponsors must submit nonclinical pharmacology and toxicology data before an investigational drug can proceed to human trials. While CDER has routinely reviewed NAMs data, the new guidance establishes four core validation principles intended to give sponsors clearer expectations.

• Context of use: Clear definition of the NAM's intended regulatory purpose
• Human biological relevance: Demonstration of how the NAM can assess toxicity in human biology
• Technical characterization: Establishment of scientific confidence through robust, reliable, and reproducible methods
• Fit-for-purpose: Assurance that the NAM supports regulatory decision-making, including drug review and potential approval

Importantly, the guidance clarifies that full validation is not always a prerequisite for a NAM to be considered in a drug development submission. A fit-for-purpose NAM, even if not fully validated, may adequately address specific toxicological concerns when evaluated within the broader weight of evidence for a given product. CDER has already accepted several NAMs in this way, including in vitro assays for skin sensitization and eye and skin irritation that now substitute for certain animal studies.²

For sponsors navigating these requirements, FDA is encouraging early consultation with the relevant review division, particularly for indication-, disease-, organ-, and endpoint-specific applications where the regulatory path may be less established.

"It is time for the FDA to shift the drug development paradigm away from the current default of using animals to predict human responses to one where these data are obtained through human-centric models which can more reliably, efficiently and ethically predict human drug reactions prior to clinical trials," said Acting CDER Director Tracy Beth Hoeg, M.D., Ph.D.

The expanded use of NAMs was also a key recommendation in the MAHA Commission's Strategy Report, which called for reducing reliance on animal studies that often fail to replicate complex human conditions.

For clinical operations teams, the guidance is a signal that preclinical study design is evolving. As NAMs gain regulatory traction, sponsors may need to reassess their nonclinical development strategies — and engage earlier with FDA — to incorporate these methods into IND-enabling programs in a way that satisfies emerging validation standards.

The draft guidance is open for public comment.

References

1. FDA Releases Draft Guidance on Alternatives to Animal Testing in Drug Development. News release. FDA. March 18, 2026. Accessed March 18, 2026. https://www.fda.gov/news-events/press-announcements/fda-releases-draft-guidance-alternatives-animal-testing-drug-development

2. General Considerations for the Use of New Approach Methodologies in Drug Development: Guidance for Industry. FDA. Accessed March 18, 2026. https://www.fda.gov/media/191589/download