FDA Intends to Phase Out mAb Animal Testing Requirement

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On April 10, 2025, FDA said it would be taking steps to replace animal testing in development of monoclonal antibody (mAb) therapies and other drugs with “human-relevant” methods the agency said are more effective (1). Aside from the clear goal of reducing animal experimentation, FDA also said it expects the shift in policy to improve drug safety, accelerate the evaluation process, and lower both R&D costs and, ultimately, drug prices.

Artificial intelligence (AI)-based computational models of toxicity and cell lines, and organoid toxicity testing in a laboratory setting, also known as New Approach Methodologies (NAMs) data, are among the approaches FDA said it will be using to reduce, refine, or potentially replace the animal testing requirement (1). Implementation was to begin immediately for investigational new drug (IND) applications—for which the inclusion of NAMs data is encouraged—and pre-existing, real-world safety data from other countries outside the United States with comparable regulatory standards, where a particular drug has already been studied in humans, will be used to make determinations of efficacy.

“For too long, drug manufacturers have performed additional animal testing of drugs that have data in broad human use internationally. This initiative marks a paradigm shift in drug evaluation and holds promise to accelerate cures and meaningful treatments for Americans while reducing animal use,” FDA Commissioner Martin A. Makary, MD, said in an agency press release (1). “By leveraging AI-based computational modeling, human organ model-based lab testing, and real-world human data, we can get safer treatments to patients faster and more reliably, while also reducing R&D costs and drug prices. It is a win-win for public health and ethics.”

FDA listed five key benefits it foresees in replacing animal testing in mAb safety evaluations:

• Advanced computer simulations. Computer modeling and AI will be leveraged to predict a drug’s behavior, which FDA believes will “drastically” reduce need for animal trials
• Human-based lab models. Use of lab-grown human “organoids” and organ-on-a-chip systems that mimic organs like the heart and liver will be promoted
• Regulatory incentives. Companies may receive streamlined review if they are able to submit strong data from non-animal tests
• Faster drug development. FDA has set a goal of getting mAb therapies to reach patients more expeditiously, without compromising safety
• Global leadership in regulatory science. Human-relevant testing methods have been pushed for in recent years by Congress and the scientific community at large, according to FDA.

“For patients, it means a more efficient pipeline for novel treatments,” Makary said in the release (1). “It also means an added margin of safety, since human-based test systems may better predict real-world outcomes. For animal welfare, it represents a major step toward ending the use of laboratory animals in drug testing. Thousands of animals, including dogs and primates, could eventually be spared each year as these new methods take root.”

FDA provided a PDF roadmap of the new policy at the time the press release was disseminated.

The announcement was among the first noteworthy policy changes under the tenure of Makary, who was sworn in as FDA commissioner on April 1, 2025 following bipartisan confirmation by the US Senate (2). The previous commissioner, Robert Califf, resigned in January 2025 as the new Trump Administration came into office, and Makary’s swearing-in came just a day after Peter Marks disclosed his resignation as director of FDA’s Center for Biologics Evaluation and Research (3,4).

References

1. FDA. FDA Announces Plan to Phase Out Animal Testing Requirement for Monoclonal Antibodies and Other Drugs. Press Release. April 10, 2025.
2. FDA. Martin A. Makary, MD, MPH, Sworn in as FDA Commissioner. Press Release. April 1, 2025.
3. Herper, M. Leaving FDA, Califf is Unapologetic—and Warns of Staff Departures. STAT. Jan. 8, 2025.
4. Marks, P. Letter to Sara Brenner, MD, MPH Acting Commissioner of Food and Drugs U.S. Food and Drug Administration. March 28, 2025. Posted by The New York Times. https://static01.nyt.com/newsgraphics/documenttools/c946b864e1dc08f9/05e7e4f0-full.pdf