Volume 2 Supplement 2
P64. T cell re-direction against Glypican-3 for immunotherapy of hepatocellular carcinoma
© Dargel et al; licensee BioMed Central Ltd. 2014
Published: 12 March 2014
Hepatocellular carcinoma (HCC) is the third most common cause of cancer related mortality world-wide and therapeutic options are very limited. A new therapeutic approach is the adoptive T cell therapy of HCC. Glypican-3 (GPC3) as a tumour associated antigen is expressed in up to 60% of all HCC but not in healthy human liver tissue. Therefore, our goal is to generate cytotoxic T lymphocytes (CTL), which are capable of recognizing and eliminating GPC3-expressing tumor cells.
Immunodominant epitopes for GPC3 have not been described yet. In this study we used Ultra Nano HPLC coupled on-line to the Q Exactive mass spectrometer to obtain a comprehensive HLA class I peptidome from a GPC3 and HLA-A2 positive hepatoma cell line. The resulting data were analysed using the MaxQuant bioinformatics platform. Two HLA-A2 bound GPC3 peptides could be identified, later on referred to as GPC3-P1 and GPC3-P2. These results enable us to target GPC3 epitopes that are presented on GPC3 positive HCC cells.
To isolate tumour reactive high avidity T cells, an allo-restricted stimulation approach was used. For stimulation of naïve T cells, autologous dendritic cells were co-transfected with GPC3 and HLA-A2 RNA and used as antigen presenting cells. T cells from the naïve T cell repertoire of HLA-A2 negative donors were co-cultured with and expanded on these HLA-A2+ GPC3+ DCs. After two weeks, MHC streptamer-positive CD8+ T cells specific for both targeted GPC3 epitopes were detected (<1%). We were able to enrich these cell populations further to 35% GPC3-P1- and 57% GPC3-P2-MHC streptamer-positive T cell lines and grew T cell clones from them. In a co-culture with GPC3-P1/ -P2 peptide loaded T2 cells we identified T cell clones displaying specific effector function by IFNγ secretion. Functional T cell clones showed strong GPC3 MHC streptamer binding.
We have cloned the first T cell receptors (TCR) to either GPC3 peptide from these T cell clones. T cells engrafted with the GPC3 specific TCRs showed strong GPC3 MHC streptamer binding. When co-cultured with GPC3 peptide loaded target cells or a GPC3 expressing hepatoma cell line (HepG2), GPC3 TCR transduced T cells secreted IFNγ. Furthermore cytotoxicity was observed by killing of up to 60% of HepG2 cells. GPC3-directed T cell therapy shows great promise for the treatment of HCC.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.