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IDENTIFICATION OF T-CELL RECEPTORS FROM THE ALLOGENEIC-HLA REPERTOIRE SPECIFIC FOR MELANOMA-ASSOCIATED ANTIGENS

PF444

de Rooij, M.1; van der Meent, M.1; van der Steen, D.1; Remst, D.1; Hagedoorn, R.1; Wouters, A.1; Kester, M.1; van Veelen, P.2; Falkenburg, F.1; Heemskerk, M.1

doi: 10.1097/01.HS9.0000559988.67161.32
Poster Session I: Gene therapy, cellular immunotherapy and vaccination - Biology & translational research
Free

1Hematology

2Proteomics, LUMC, Leiden, Netherlands

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Background:

Melanoma-associated antigens (MAGE) are highly expressed in multiple myelomas as well as solid tumors, but silent in normal cells except for male germ line cells. This tumor-restricted expression makes it an excellent target for adoptive T cell therapy. However, due to thymic selection high-affinity T cells against self-antigens presented in the context of self-HLA are deleted from the T-cell repertoire of a patient. To overcome this problem, we identify T-cell receptors (TCRs) from the allogeneic-HLA repertoire instead of the autologous-HLA repertoire.

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Aims:

To identify high-affinity T-cell receptors from the allogeneic-HLA repertoire specific for melanoma-associated antigens.

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Methods:

In this study we selected MAGE peptides by peptide elution experiments from HLA class I and subsequent mass spectrometric analysis of tumor cells. Only peptides binding in the most frequently occurring HLA-alleles were selected. From the identified peptides, HLA-tetramers were formed to isolate peptide specific CD8+ T cells from healthy allogeneic donors. Avidity of the selected T-cell clones was determined by stimulation assays including a broad range of MAGE expressing tumor cell lines. To examine off-target recognition, T-cell clones were stimulated with MAGE negative cell lines and EBV-transformed B lymphoblastic cells expressing all prevalent HLA molecules.

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Results:

MAGE peptides were eluted from multiple myelomas, EBV-transformed lymphoblastic cells, acute myeloid leukemia and ovarium carcinomas. For MAGE-A1, T-cell clones specific for four different epitopes presented in the context of HLA-A*01:01, HLA-A*03:01, HLA-B*07:02 and HLA-C*07:02 were selected. For MAGE-A3, T-cell clones specific for one epitope presented in the context of HLA-A*01:01 and HLA-B*35:01 were identified. The selected T-cell clones demonstrated efficient recognition of MAGE-A1 or MAGE-A3 positive multiple myeloma and solid tumor cell lines without detectable cross-reactivity.

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Summary/Conclusion:

MAGE-A1 and MAGE-A3 specific T-cell clones were isolated from the allogeneic-HLA repertoire of healthy individuals. The identified clones were activated upon exposure to MAGE-A1 or MAGE-A3 positive tumor cell lines and showed limited off-target recognition. These newly identified TCRs could potentially be used for TCR-gene therapy strategies targeting MAGE-A1 or MAGE-A3 positive tumors.

Copyright © 2019 The Authors. Published by Wolters Kluwer Health Inc., on behalf of the European Hematology Association.