Identification and characterization of transgenic tcrsapplication to liver cancer adoptive t-cell therapy

Resumen

Using HHD-DR1 mice immunized with an adenovirus expressing human GPC3, we have induced murine T cells specific for the HLA-A*02:01-restricted GPC3(522-530) epitope. By establishing clones from GPC3(522-530)-specific murine CD8 T cells, we have identified 20 different pairs of TCRα and TCRβ genes. Seven of these murine TCRs have been cloned and all of them enabled human T cells to recognize GPC3(522-530)-peptide pulsed HLA-A*02:01+ cells exhibiting different functional avidity. However, only three TCRs (TCR-3, -4 and -5) recognized HLA-A*02:01+GPC3+ tumor cells in vitro, with TCR-4 and -5 showing strong effector functions. Strikingly, the functional avidity of TCRs for the GPC3(522-530) epitope when pulsed as a soluble peptide did not correlate with the reactivity against GPC3+ HLA-A*02:01+ tumor cells. Thus, TCR-4, which ranked among the TCRs with the lowest functional avidity against the pulsed peptide, was able to recognize all tested GPC3+ HLA-A*02:01+ tumor cells, including those expressing very low levels of GPC3 or low levels of HLA-A*02:01. Interestingly, although in vitro TCR-4 and -5 engineered T cells exhibited comparable effector functions against GPC3+HLA*02:01 tumor cells, in vivo only TCR-4 T cells were able to eradicate GPC3+HLA-A*02:01+ HCC tumors in NSG mice. The better engraftment of TCR-4-T cells may account for their greater antitumor capacity in ACT regimens. TCR-4 is postulated as our main clinical candidate to develop a TCR-based therapy targeting GPC3 for the treatment of HCC.