The U.S. Food and Drug Administration (FDA) has released a draft guidance indicating that non-human primates may no longer be required for many monoclonal antibody toxicity studies, an important step that could reshape preclinical drug development.
According to the FDA, pharmaceutical companies developing monoclonal antibodies (mAbs) may now reduce or eliminate six-month toxicity studies on non-human primates (NHPs), including macaque monkeys. These studies have traditionally been part of the safety package required before moving new biologic drugs into human clinical trials.
The FDA explained that scientific advancements, particularly in pharmacology, toxicology, and modeling systems allow for more precise prediction of human responses without relying heavily on primate studies.
These long-term studies can involve more than 100 monkeys per drug program and cost approximately $50,000 per animal, creating substantial financial and ethical concerns within the industry.
FDA Commissioner Marty Makary stated that the agency is fulfilling its roadmap to reduce animal use in drug evaluation. He noted that the change may shorten drug development timelines and lower research and development costs, potentially leading to more affordable medicines.
This shift comes at a time when U.S. pharmaceutical companies are under pressure to remain competitive with China’s rapidly expanding biotechnology sector, where drug development costs are often lower. The cost of monkeys used for research in China has reportedly decreased since the COVID-19 pandemic, making global competition more pronounced.
Animal testing has been a cornerstone of drug safety assessment since the thalidomide tragedy of the 1950s–60s, which caused severe birth defects in approximately 10,000 children after the drug was given to pregnant women without adequate safety testing. This event prompted stricter toxicology requirements, including testing on animals before human exposure.
Despite growing scientific alternatives, phasing out animal testing has been slow due to regulatory caution and the need to maintain safety standards.
The UK recently announced a £30 million investment to develop non-animal drug testing technologies, including artificial intelligence and next-generation testing tools. This reflects a global movement toward reducing the reliance on animals in research.
The FDA has not specified which monoclonal antibodies will qualify for reduced primate testing. However, dozens of mAb therapies have been approved in the U.S. in recent years for conditions such as:
Cancer
Autoimmune diseases
Infectious diseases (including COVID-19)
The draft guidance indicates that future mAb candidates may undergo alternative toxicity testing strategies without long-term primate studies.
Conclusion
The FDA’s draft guidance represents a significant shift in the regulatory approach to monoclonal antibody development. While the move aligns with global trends and may reduce costs and animal use, experts note that the transition must maintain strong safety standards. The proposal remains open for public and scientific feedback before final implementation.
Reference
1. U.S. Food and Drug Administration. “FDA Releases Draft Guidance Reducing Testing in Non-Human Primates for Monoclonal Antibodies.” Last modified December 13, 2025. https://www.fda.gov/news-events/press-announcements/fda-releases-draft-guidance-reducing-testing-non-human-primates-monoclonal-antibodies.
(Rh/TL/MSM)