Volume 2 Supplement 2

Abstracts from the 1st Immunotherapy of Cancer Conference (ITOC1)

Open Access

P29. T-cell responses to oncogenic Merkel cell polyomavirus proteins distinguish Merkel cell carcinoma patients from healthy donors

  • L Lyngaa1,
  • NW Pedersen1,
  • D Schrama2,
  • CA Thrue1,
  • D Ibrani3,
  • O Met1,
  • P thor Straten1,
  • P Nghiem3,
  • JC Becker2 and
  • SR Hadrup1
Journal for ImmunoTherapy of Cancer20142(Suppl 2):P20

https://doi.org/10.1186/2051-1426-2-S2-P20

Published: 12 March 2014

Purpose

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with strong evidence for viral carcinogenesis. The association of MCC with the Merkel cell polyomavirus (MCPyV) may explain the explicit immunogenicity of MCC. Indeed, MCPyV-encoded proteins are likely targets for cytotoxic immune responses to MCC as they are both foreign to the host and necessary to maintain the oncogenic phenotype. However, to date only a single MCPyV-derived CD8 T-cell epitope have been described, thus impeding specific monitoring of T-cell responses to MCC.

Method

To overcome this limitation, we scanned the MCPyV oncoproteins large T and small T antigen and the virus-capsid protein VP1 for potential T-cell epitopes, and tested for major histocompatibility complex (MHC) class I affinity. We confirmed the relevance of these epitopes using a high-throughput platform for T-cell enrichment and combinatorial encoding of MHC class I multimers.

Results

In peripheral blood from 38 MCC patients and 30 healthy donors we identified 53 MCPyV-directed CD8+ T-cell responses against 35 different peptide sequences. Strikingly, T-cell responses against oncoproteins were exclusively present in MCC patients, but not in healthy donors. We further demonstrate both the processing and presentation of the oncoprotein-derived epitopes, as well as the lytic activity of oncoprotein-specific T cells towards MHC-matched MCC cells. Demonstrating the presence of oncoprotein-specific T cells among tumour infiltrating lymphocytes ex vivo further substantiated the relevance of the identified epitopes.

Conclusion

These T-cell epitopes represent ideal targets for antigen specific immune therapy of MCC, and enables tracking and characterisation of MCPyV specific immune responses.

Authors’ Affiliations

(1)
Center for Cancer Immune Therapy, Herlev University Hospital
(2)
General Dermatology, Medical University of Graz
(3)
Department of Medicine/Dermatology, University of Washington

Copyright

© Lyngaa et al; licensee BioMed Central Ltd. 2014

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.

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