This workstream critically evaluates when non-human primates (NHPs), particularly cynomolgus macaques, are predictive models for human immunotoxicity and when their use may be scientifically uninformative. While NHPs are often selected due to target cross-reactivity, comparable immune architecture, and pharmacologic activity, translational performance varies substantially by mechanism, immune context, and endpoint. The project examines genomic homology, immune cell phenotypes, cytokine signaling kinetics, Fc receptor biology, cytotoxic function, TDAR responses, and immunogenicity patterns to identify where immune biology is conserved versus meaningfully divergent. Case studies, ranging from underprediction of immune-related adverse events with checkpoint inhibitors to successful anticipation of systemic immune activation with CD40 agonists, anchor a structured assessment of predictive success and failure.
A central deliverable is a mechanism-based Weight-of-Evidence framework to guide species selection and study design. This framework integrates comparative genomics, cross-species in vitro pharmacology, historical translational data, and contextual factors such as age, immune tone, and genetic diversity. It also incorporates emerging New Approach Methodologies (NAMs)âincluding human in vitro cytokine release assays, cytotoxicity platforms, and immune-competent microphysiological systemsâto inform when NHP studies add value and when alternative approaches may be more appropriate. The goal is to support responsible 3Rs implementation while preserving scientific rigor and regulatory confidence in immuno-safety decision-making.