Construction and functional characterization of a fully human anti‐CD19 chimeric antigen receptor (huCAR)‐expressing primary human T cells

Abstract

Abstract Although remarkable results have been attained by adoptively transferring T cells expressing fully murine and/or humanized anti‐CD19 chimeric antigen receptors (CARs) to treat B cell malignancies, evidence of human anti‐mouse immune responses against CARs provides a rationale for the development of less immunogenic CARs. By developing a fully human CAR (huCAR), these human anti‐mouse immune responses are likely eliminated. This, perhaps, not only increases the persistence of anti‐CD19 CAR T cells—thereby reducing the risk of tumor relapse—but also facilitates administration of multiple, temporally separated doses of CAR T cells to the same recipient. To these ends, we have designed and constructed a second‐generation fully human anti‐CD19 CAR (or huCAR19) containing a fully human single‐chain variable fragment (ScFv) fused with a CD8a hinge, a 4‐1BB transmembrane domain and intracellular T cell signaling domains of 4‐1BB and CD3z. T cells expressing this CAR specifically recognized and lysed CD19 + target cells produced cytokines and proliferated in vitro. Moreover, cell volume data revealed that our huCAR construct cannot induce antigen‐independent tonic signaling in the absence of cognate antigen. Considering our results, our anti‐CD19 huCAR may overcome issues of transgene immunogenicity that plague trials utilizing CARs containing mouse‐derived ScFvs. These results suggest that this huCAR19 be safely and effectively applied for adaptive T cell immunotherapy in clinical practice.