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OR10 Tumor antigens presented by the HLA-A02:01 of breast cancer patient-derived xenografts
Aim Breast cancer is the second leading cause of cancer death in women, yet only a few antigens are available for directing immune therapies to a patient’s breast tumor. In this study we establish a new system for identifying tumor-specific antigens presented by the class I HLA of breast tumors. Our...
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Published in: | Human immunology 2016-09, Vol.77, p.9-9 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Aim Breast cancer is the second leading cause of cancer death in women, yet only a few antigens are available for directing immune therapies to a patient’s breast tumor. In this study we establish a new system for identifying tumor-specific antigens presented by the class I HLA of breast tumors. Our approach relies on generating a breast cancer HLA peptide-ligand reference database coupled with isolation of peptides from the HLA of patient-derived breast cancer xenografts (PDX). This HLA PDX approach can rapidly identify targets for existing and emerging cancer immune therapies. Methods A tumor-specific HLA reference peptide ligand library was constructed using 3 breast epithelial tumor cell lines and 1 healthy breast epithelial line. Cells were transfected to secrete HLA-A∗02:01, secreted HLA was affinity purified, HLA-bound peptides were eluted, separated by HPLC, and HLA-A∗02:01 breast cancer peptides were analyzed by mass spectroscopy. To validate the peptides as relevant targets for human breast tumors in vivo, HLA was extracted from PDX-derived tumors and the presence of specific peptides were confirmed in these primary tumors. Results In 20 PDX tumor lines, 7 of the tumors were A∗02:01, half of which expressed detectable A∗02:01. When evaluated for candidate peptide:HLA expression, the HCI-015 triple negative PDX xenograft expressed high levels of the Macrophage Inhibitory Factor19–27 (MIF) peptide, a peptide that is expressed solely in breast cancer cell lines and primary tumors but not healthy tissues. We are currently expanding HCI-015 PDX for additional HLA extractions. Conclusions These data suggest that PDX tumors can be used as surrogates to human tumors for the direct identification of tumor-specific antigens. The use of a peptide library generated from several breast cancer cell lines allows peptides to be identified with increased sensitivity. Furthermore, expression of the candidate MIF19-27 peptide on HCI-015 provides compelling evidence that certain tumor-antigens are conserved among cell lines, tumors, and in vivo models of breast cancer. Such antigens provide a unique therapeutic window that can be exploited for targeted immunotherapies. |
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ISSN: | 0198-8859 1879-1166 |
DOI: | 10.1016/j.humimm.2016.07.022 |