The U.S. Food and Drug Administration (FDA) has issued new draft guidance to reduce the use of non-human primates for certain monoclonal antibody (mAb) products. These laboratory-produced antibodies are engineered to target disease in the same way as those naturally made by the immune system.
For monospecific antibodies, which target one specific molecule, and work through well-understood human biology, the FDA indicates that long-term primate toxicity studies lasting six months may be reduced or removed altogether. The agency also points to the increasing use of modern human-relevant tools, such as computer-based methods, organoid systems and real-world human safety data, to help assess the safety of new medicines.
This reflects long-standing scientific concerns about how inaccurately primate studies predict human responses for many biological products, and represents a practical step toward more efficient, human-focused drug evaluation. The proposal is also consistent with the FDA’s 2025 roadmap to reduce reliance on animal testing.
Actions like this are important because progress depends on implementation, not just intention. Roadmaps only deliver meaningful change when high-level commitments are followed by concrete steps, and this draft guidance is a welcome indication that the FDA is beginning to put its strategy into practice.
There are further opportunities to build on this progress, including addressing animal tests highlighted in our Replace Animal Tests (RAT) List. These tests continue despite the availability of valid non-animal methods, largely because of gaps in guidance and slow removal of outdated requirements. Whilst only some are relevant to the FDA, the principle remains clear: when reliable non-animal methods are available, they should be used in place of animal tests.
The draft guidance also reflects scientific principles we consistently highlight through our role as Secretariat to the International Council on Animal Protection in Pharmaceutical Programs (ICAPPP). These include reducing the reliance on specific animal species as the default option, selecting models based on biological relevance, and using more human-relevant tools such as cell-based and computer-based methods. This is relevant because the FDA’s proposal is intended to supplement international guidance on medicines testing, including regulation ICH S6, which ICAPPP has encouraged regulators to review. It is promising to see these concepts gaining momentum in wider efforts to update regulations.
Looking ahead, additional opportunities exist to modernise international requirements. One important area is the routine use of a second species (typically dogs) in medicines testing. This requirement is embedded in ICH M3, another internationally used guideline for medicines testing. Growing evidence supports a more flexible, science-driven approach that would reduce unnecessary animal testing. We have done extensive work on this and hope that progress to reduce primate testing will help spark broader updates to outdated regulatory testing requirements.
Our Deputy Director of Science and Regulatory Affairs, Laura Alvarez, said: “Reducing tests on primates is a sensible and necessary step away from outdated methods and towards modern, human-relevant science. We are encouraged to see movement on the FDA’s roadmap and hope this progress accelerates a wider transition away from long-standing animal testing requirements where non-animal approaches exist.”