The U.S. Food and Drug Administration (FDA) has proposed new guidelines to reduce or eliminate the use of non-human primates in testing certain antibody therapies. This move is part of a broader effort by the agency to limit animal experiments in drug development.
According to draft guidance released on Tuesday, for monospecific antibodies—those targeting a single epitope—three-month toxicity studies in non-rodent models will be considered sufficient, replacing the previous requirement for six-month studies. Companies will still need to provide additional safety data, such as pharmacologic information, mechanism-of-action evidence, or results from other assays and toxicology research.
The FDA also indicated that if substantial animal data exists from other antibody agents targeting the same molecule, companies may not need to conduct new toxicology studies at all—not even the shortened three-month version.
Despite these changes, the FDA continues to emphasize quality standards for non-clinical safety data. Toxicology studies must be done in species relevant to the drug's action and clearly show that the antibody binds its intended molecular target and produces its expected effect.
In a statement on Tuesday, FDA Commissioner Marty Makary said: “These new guidelines are part of the agency’s ‘commitment to eliminate animal testing requirements in drug evaluation,’ an effort that he added will ‘accelerate cures and meaningful treatments for Americans.’”
Earlier this year, the FDA announced plans to phase out animal testing for monoclonal antibodies by using alternative methods such as artificial intelligence-based models and computer simulations. These tools can assess drug toxicity and simulate how monoclonal antibodies behave within human bodies. The agency also highlighted laboratory-grown human organoids and organ-on-a-chip systems as promising technologies for evaluating therapeutic effects on human tissues.
Reactions within the industry have been mixed. Organoid manufacturers and advocates for animal rights support these changes. Tomasz Kostrzewski, chief scientific officer of CN Bio—which develops organ-on-a-chip systems—told BioSpace: “There’s a place for animals in drug discovery, but animal research shouldn’t be the go-to.”
However, some experts remain cautious about relying solely on alternatives to animal testing. Joseph Wu, Stanford Medicine cardiologist and co-founder of Greenstone Biosciences—a company supporting drug discovery with stem cells and organoids—said: “There are certain aspects of living systems that we can’t model yet.”
