Rapid generation of a mouse model for evaluating on-target normal tissue toxicity of human CAR-T cells using replication-defective recombinant adenovirus

Abstract

IntroductionThe on-target off-tumor toxicity of chimeric antigen receptor-engineered T cells (CAR-T) might lead to fatal side effects in cancer patients, which remains as a major obstacle to the clinical application of CAR-T immunotherapy. The off-tumor on-target normal tissue toxicity of CAR-T cells needs to be evaluated in preclinical studies using rational animal models. ObjectivesWe aim to develop a rational animal model for assessing the off-tumor on-target normal tissue toxicity of various CAR-T cell designs quickly. MethodsWe used a recombinant adenovirus type 5 carrying human HER2/ERBB2 (Ad5-HER2) or CD47 gene (Ad5-CD47) to rapidly generate a mouse model with tunable human antigen expression on normal liver tissue to determine immunotoxicity of traditional CAR-T and hypoxia-response CAR-T cells in vivo. ResultsThe obvious liver damage and lymphocyte infiltration were not observed in mice with human antigen-high livers 8 days post-infection. Interestingly, the lethal liver damage, systemic cytokine release and CAR-T cells infiltration in liver were only observed in mice that received traditional CAR-T cells, but not in hypoxia-response CAR-T cells. ConclusionAdenovirus-based expression of target antigen in normal mouse tissue may be a useful method for assessing on-target CAR-T cell toxicity in normal tissues, especially various CAR-T cell designs that have the potency of conditional regulation in tumor microenvironment (TME).