Role of Immunotoxicology in IND Submissions: Cytokine Release and Immunogenicity Testing
Immunotoxicology focuses on the adverse effects of chemical substances on the immune system, encompassing immunosuppression, immunostimulation, hypersensitivity reactions, and autoimmunity. In the context of IND submissions, immunotoxicity evaluation is critical for biologics, nanoparticles, and small molecules with immunomodulatory effects or structural alerts for immune reactivity. Unanticipated immune activation or suppression can have severe clinical consequences and must be identified early in development.
Cytokine release syndrome (CRS), a potentially life-threatening immune response, is of particular concern for immunotherapies such as monoclonal antibodies, T-cell engagers, and certain nanoparticles. In vitro cytokine release assays using human peripheral blood mononuclear cells (PBMCs) are employed to assess cytokine profiles following compound exposure, typically measuring IL-6, TNF-α, IFN-γ, and other inflammatory markers. These assays can identify agents likely to provoke CRS in clinical settings.
In vivo immunotoxicity assessments evaluate lymphoid organ weights, histopathology of the thymus and spleen, and immune cell counts. Functional assays—such as T-cell-dependent antibody response (TDAR), natural killer (NK) cell activity, and delayed-type hypersensitivity (DTH)—provide data on immune competence and potential suppression. For compounds with repeated exposure, immunogenicity testing detects the formation of anti-drug antibodies (ADAs), which can reduce efficacy or enhance toxicity.
Guidelines such as ICH S8 outline expectations for immunotoxicity testing based on structural class, pharmacological targets, and prior evidence. Immunotoxicology data help define clinical eligibility criteria, identify populations at risk (e.g., immunocompromised patients), and inform immune monitoring protocols during trials. Their inclusion in IND filings ensures a more complete risk assessment, particularly for therapies designed to interact with or modulate immune pathways.