December 2, 2025 — The U.S. Food and Drug Administration (FDA) has released new draft guidance aimed at significantly reducing, and in some cases eliminating, six-month non-human primate (NHP) toxicity studies for certain monoclonal antibody (mAb) products. The move marks a major step in the agency’s ongoing efforts to modernize nonclinical drug evaluation and transition toward human-relevant, non-animal methods.
According to the FDA, the new approach incorporates knowledge-based risk assessments supported by computational toxicology tools, organoid systems, and real-world human safety data, enabling more efficient and scientifically advanced safety evaluations.
FDA Commissioner Dr. Marty Makary emphasized the broader impact of this policy shift:
“Modern science has given us far more effective and humane ways of evaluating drug safety than animal testing. This reform may reduce the time it takes to bring a drug to market and lower R&D costs – benefits that can ultimately translate to lower drug prices.”
A typical nonclinical package for monoclonal antibody products can involve over 100 non-human primates, with each animal costing approximately $50,000. Despite such extensive testing, many biologics that clear NHP studies fail at later stages due to safety or efficacy concerns in humans.
Dr. Richard Pazdur, Director of the FDA’s Center for Drug Evaluation and Research, noted that integrating modern risk assessments allows regulators to make “better-informed safety decisions without compromising the rigorous standards that patients depend on.”
The draft guidance aligns with the agency’s long-term roadmap for reducing animal testing across therapeutic areas. The FDA continues to collaborate with the National Institutes of Health, ICCVAM, and international partners to validate new approach methodologies (NAMs) and expand their regulatory application.
Once finalized, the guidance will supplement the FDA’s existing S6 Addendum (2012), which supports flexible, science-based nonclinical evaluation strategies for biotechnology-derived products.
The initiative follows a public workshop held in July 2025, where sponsors, researchers, and patient groups discussed practical strategies to reduce animal use while maintaining public safety.
Comments on the draft guidance may be submitted via the FDA’s request-for-comment portal.
