Transcriptional responses of T cells activated via CD22-specific T cell receptor compared to CD22-specific chimeric antigen receptor

Chimeric antigen receptor (CAR) T cells are effective against B-cell malignancies but are associated with cytokine-driven inflammatory toxicities such as cytokine release syndrome (CRS). Historically, T cell receptor (TCR) engineered T cell therapies are rarely associated with CRS. However, it is challenging to compare diverse cell products utilized in different clinical contexts and against different antigens. In this study, TCR and CAR were made to target the same source of antigen, CD22, expressed by B-cell malignancies: the TCR recognizes CD22-derived peptide processed and presented in the context of HLA-A*02:01, and the CAR recognizes CD22 protein expressed on the cell surface. In vivo studies comparing the CD22 TCR-T cells to CD22 CAR-T cells demonstrated that the TCR-T cells could clear leukemia without inducing systemic proinflammatory cytokine elevation, whereas CD22 CAR-T cells induced high levels of circulating proinflammatory cytokine reminiscent of CRS. T cells activated through either the TCR or CAR by an identical leukemia cell line demonstrated differential transcriptional responses. T cells activated via the CAR had disproportionate and significant upregulation of inflammatory gene sets compared to T-cells activated via the TCR. Overall design: From human peripheral blood mononuclear cells (PBMCs), CD8+ and CD4+ T cells were isolated. CD8+ and CD4+ T cells were each transduced to express either the CD22 TCR or the CD22 CAR. In some groups, CD22 TCR-transduced T cells were then co-transduced to express exogenously added CD8alpha-beta heterodimers (exCD8). Each transduced T cell product was co-cultured with HLA-A*02:01 and CD22 positive leukemia cell line, BV173, at an E:T ratio of 1:1 (2e7 cells each per well) in 24-well plate. After 6 hours of co-culture, residual leukemia cells were depleted using magnetic isolation technique. The purity of T cells in the post-leukemia-depletion samples were confirmed with flow cytometry analysis. Non-stimulated control T cells (without co-culture with leukemia cells) also underwent identical magnetic isolation processes for the purpose of equalizing the condition. Bulk RNA was extracted from each sample. Experiment was set up in three biological replicates and RNA extraction was performed in a single batch.