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Resected tumours from MHC haplotype HLA-A*02:01 patients will be collected and mass
spectrometry as well as proteomics analysis performed to analyze MHC-bound peptides
to assess the entirety of expressed tumour proteins, respectively. Potential neoantigens
will be validated by whole exome sequencing. Additionally, HCC cells will be isolated
from tumours and established in culture; the HCC cells will undergo the aforementioned
methods and verify preceding results.

Results: Flow cytometric data demonstrated a massive expansion of specific CD8 T cell
immune responses against mAFP. Immunization with the optimized peptide resulted in
a frequency of up to 30% mAFP-specific CD8 T cells of total CD8 T cells compared to
<1% after immunization with the wildtype peptide. T cells were detected by intracellular
cytokine staining and flow cytometry.

Conclusions: The TAA mAFP is a promising target to establish effective
immunotherapeutic treatments. In contrast to conventional vaccination approaches,
the combination of primary dendritic cell immunization with subsequent injection of
agonistic, co-stimulatory antibodies is able to massively expand tumour-specific CD8 T
cells, capable of targeting AFP-expressing HCC.

ePOSTER ABSTRACTS
Disclosure of Interest: None Declared

246 Programme & Abstracts • HCC Summit