Preclinical development of T-cell receptor-engineered T-cell therapy targeting the 5T4 tumor antigen on renal cell carcinoma

5T4 (trophoblast glycoprotein, TPBG) is a transmembrane tumor antigen expressed on more than 90% of primary renal cell carcinomas (RCC) and a wide range of human carcinomas but not on most somatic adult tissues. The favorable expression pattern has encouraged the development and clinical testing of 5T4-targeted antibody and vaccine therapies. 5T4 also represents a compelling and unexplored target for T-cell receptor (TCR)-engineered T-cell therapy. Our group has previously isolated high-avidity CD8(+) T-cell clones specific for an HLA-A2-restricted 5T4 epitope (residues 17-25; 5T4(p17)). In this report, targeted single-cell RNA sequencing was performed on 5T4(p17)-specific T-cell clones to sequence the highly variable complementarity-determining region 3 (CDR3) of T-cell receptor alpha chain (TRA) and beta chain (TRB) genes. Full-length TRA and TRB sequences were cloned into lentiviral vectors and transduced into CD8(+) T-cells from healthy donors. Redirected effector T-cell function against 5T4(p17) was measured by cytotoxicity and cytokine release assays. Seven unique TRA-TRB pairs were identified. All seven TCRs exhibited high expression on CD8(+) T-cells with transduction efficiencies from 59 to 89%. TCR-transduced CD8(+) T-cells demonstrated redirected cytotoxicity and cytokine release in response to 5T4(p17) on target-cells and killed 5T4(+)/HLA-A2(+) kidney-, breast-, and colorectal-tumor cell lines as well as primary RCC tumor cells in vitro. TCR-transduced CD8(+) T-cells also detected presentation of 5T4(p17) in TAP1/2-deficient T2 target-cells. TCR-transduced T-cells redirected to recognize the 5T4(p17) epitope from a broadly shared tumor antigen are of interest for future testing as a cellular immunotherapy strategy for HLA-A2(+) subjects with 5T4(+) tumors.