On Dec. 2, 2025, the FDA released draft guidance that could reduce the use of nonhuman primates (NHPs) in preclinical testing of monoclonal antibodies. According to the guidance, which the FDA released for the purpose of soliciting comments, “In general, studies longer than 3 months in nonrodent species (e.g., NHPs, dogs, and mini-pigs) are not warranted to evaluate toxicities … when data from 3-month studies are supplemented with a weight-of-evidence (WoE) risk assessment.”