02278nas a2200229   4500000000100000008004100001260001500042653002600057653003100083653003100114653003400145653002400179653003300203100001600236700002000252245015300272856007200425300001100497490000800508520151800516022001402034       2026                            d  c2026-09-0110aMonoclonal antibodies10anew approach methodologies10aNon-human primate toxicity10aNonclinical safety assessment10aRegulatory toxicity10aRepeat-dose toxicity studies1 aYanning Hao1 aNakissa Sadrieh00aFDA CDER analysis of non-human primate (NHP) data in monoclonal antibody (mAb) development to support the streamlining of nonclinical safety studies  uhttps://www.sciencedirect.com/science/article/pii/S0273230026000978  a1061240 v1703 aA retrospective analysis of nonclinical study reports submitted in regulatory packages of FDA-approved mAbs, excluding antibody–drug conjugates, was conducted. This analysis was limited to the period between January 2020 and April 2025. For highly target-specific mAbs, the incremental contribution of long-term animal studies to regulatory safety assessment was evaluated. FDA review documents were examined to assess study duration, species selection, and the regulatory relevance of toxicological findings to determine whether long-term in vivo studies submitted in Biologics License Applications (BLAs) identified new safety signals beyond those seen in shorter-term studies. Among the mAbs evaluated, long-term NHP toxicity studies were included in more than half of the development programs but rarely altered regulatory conclusions regarding human risk. Additional findings were predominantly attributable to known pharmacology or species-specific immunogenicity and generally did not affect no-observed-adverse-effect-level (NOAEL) determination, clinical trial design, or labeling. No long-term study in this analysis identified unanticipated off-target toxicities that fundamentally altered the overall safety assessment. These results are consistent with principles articulated in the FDA's 2025 Roadmap for Reducing Animal Testing in Preclinical Safety Studies and provide descriptive information relevant to recent draft FDA guidance on streamlined nonclinical safety studies for monospecific mAbs.  a0273-2300