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Abstract

BACKGROUND & AIMS: Cancer therapies are being developed based on our ability to direct T cells against tumor antigens. Glypican-3 (GPC3) is expressed by 75% of all hepatocellular carcinomas (HCC), but not in healthy liver tissue or other organs. We aimed to generate T cells with GPC3-specific receptors that recognize HCC and used them to eliminate GPC3-expressing xenograft tumors grown from human HCC cells in mice. METHODS: We used mass spectrometry to obtain a comprehensive peptidome from GPC3-expressing hepatoma cells after immune-affinity purification of human leukocyte antigen (HLA)-A2 and bioinformatics to identify immunodominant peptides. To circumvent GPC3 tolerance resulting from fetal expression, dendritic cells from HLA-A2-negative donors were cotrans-fected with GPC3 and HLA-A2 RNA to stimulate and expand antigen-specific T cells. RESULTS: Peptide GPC3(367) was identified as a predominant peptide on HLA-A2. We used A2-GPC3(367) multimers to detect, select for, and clone GPC3-specific T cells. These clones bound the A2-GPC3(367) multimer and secreted interferon-g when cultured with GPC3(367), but not with control peptide-loaded cells. By genomic sequencing of these T-cell clones, we identified a gene encoding a dominant T-cell receptor. The gene was cloned and the sequence was codon optimized and expressed from a retroviral vector. Primary CD8(+)T cells that expressed the transgenic T-cell receptor specifically bound GPC3(367) on HLA-A2. These T cells killed GPC3-expressing hepatoma cells in culture and slowed growth of HCC xenograft tumors in mice. CONCLUSIONS: We identified a GPC3(367)-specific T-cell receptor. Expression of this receptor by T cells allows them to recognize and kill GPC3-positive hepatoma cells. This finding could be used to advance development of adoptive T-cell therapy for HCC.