The U.S. Food and Drug Administration (FDA) has issued new draft guidance identifying specific drug product types for which six-month non-human primate (NHP) toxicity studies can be reduced or fully eliminated. The proposal marks another major milestone in the agency’s ongoing effort to modernize nonclinical drug evaluation, accelerate therapeutic development, and substantially reduce reliance on animal testing.
The guidance focuses on updating long-standing approaches to preclinical safety research, especially for monoclonal antibodies and similar biotechnology-derived products. Traditionally, these programs have required extensive NHP testing, often involving more than 100 animals and significant expense — approximately $50,000 per primate. Despite this, many drug candidates that pass animal toxicity testing ultimately fail during human evaluation due to safety or efficacy concerns, prompting regulators and scientists to reevaluate the predictive value of certain animal models.
In this latest draft recommendation, the FDA proposes replacing long-term NHP studies with a science-based risk-assessment model that integrates emerging human-relevant technologies. These include computational toxicology models, human organoid systems, and real-world clinical safety data — tools that the agency says offer greater accuracy, efficiency, and ethical alignment.
“We are delivering on our roadmap commitment to eliminate animal testing requirements in drug evaluation and our promise to accelerate cures and meaningful treatments for Americans,” said FDA Commissioner Marty Makary, M.D., M.P.H. He emphasized that modern technologies now provide far more effective and humane ways of assessing drug safety than animal testing. “This reform may reduce the amount of time it takes to bring a drug to market and lower research and development costs, which can translate into lower drug prices.”
Dr. Richard Pazdur, Director of the Center for Drug Evaluation and Research, echoed this view, noting that integrating advanced methodologies allows regulators to make better informed decisions while maintaining the agency’s high safety standards. “By incorporating a knowledge-based risk assessment, we can make better informed decisions about drug safety while maintaining the rigorous safety standards that patients depend on,” he said. “This evolution in our approach reflects both scientific progress and our responsibility to use the most effective tools for drug evaluation.”
The draft guidance aligns with the FDA’s broader roadmap for reducing or replacing animal testing in nonclinical studies. The agency plans continued collaboration with federal partners such as the National Institutes of Health and the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM), as well as with international regulators, to validate and expand the use of new approach methodologies (NAMs) across therapeutic categories.
When finalized, the new guidance will supplement the FDA’s existing 2012 S6 Addendum to the Preclinical Safety Evaluation of Biotechnology-Derived Pharmaceuticals, which emphasized scientific flexibility and product-specific risk assessment. The updates are expected to promote more efficient drug development pathways while maintaining robust public health safeguards.
The FDA’s move follows extensive stakeholder engagement, including a public workshop held in July 2025. Researchers, pharmaceutical sponsors, technologists, and patient advocates contributed insights on strategies to reduce animal testing without compromising patient safety. These discussions have helped shape the ongoing modernization of the agency’s regulatory science framework.
As the FDA continues refining its policies, this draft guidance represents a significant shift in how biotechnology-derived therapeutics may be evaluated in the years ahead — one that prioritizes human-relevant science, accelerates medical innovation, and supports the ethical reduction of animal use in research.