Identification of a novel HLA-A24-restricted cytotoxic T lymphocyte epitope peptide derived from mesothelin in pancreatic cancer

// Mariko Tsukagoshi 1, 2 , Satoshi Wada 3, 4 , Seiko Hirono 5 , Shintaro Yoshida 4 , Erica Yada 4 , Tetsuro Sasada 4 , Ken Shirabe 1, 3 , Hiroyuki Kuwano 3 and Hiroki Yamaue 5 1 Division of Hepatobiliary and Pancreatic Surgery, Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi Gunma 371-8511, Japan 2 Department of Innovative Cancer Immunotherapy, Gunma University Graduate School of Medicine, Maebashi Gunma 371-8511, Japan 3 Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi Gunma 371-8511, Japan 4 Department of Cancer Immunotherapy, Kanagawa Cancer Center, Asahi-ku, Yokohama Kanagawa 241-8515, Japan 5 Second Department of Surgery, Wakayama Medical University, Wakayama 641-8510, Japan Correspondence to: Hiroki Yamaue, email: yamaue-h@wakayama-med.ac.jp Keywords: mesothelin; epitope peptide; cancer vaccine; immunotherapy; pancreatic cancer Received: January 16, 2018      Accepted: July 12, 2018      Published: July 31, 2018 ABSTRACT Pancreatic cancer involves highly malignant tumors, and the development of new therapeutic strategies is critical. Mesothelin is overexpressed in infiltrating pancreatic cancer cells and plays an important role in the invasion and migration processes. In this study, we focused on mesothelin as a tumor-specific antigen target for a pancreatic cancer vaccine. We first investigated the mesothelin-derived epitope peptide restricted to HLA-A * 2402. A total of 19 candidate peptides were synthesized, and we then determined their potential to induce peptide-specific cytotoxic T lymphocytes (CTLs). Peptide-specific CTLs were induced by five peptides derived from mesothelin, and these CTLs successfully exhibited peptide-specific IFN-γ production. After the expansion of each CTL, two CTL lines were established, which were induced by mesothelin-10-5 peptide (AFYPGYLCSL). These CTL lines exhibited peptide-specific cytotoxicity and IFN-γ production. Moreover, we were able to generate mesothelin-10-5 peptide-specific CTL clones. These CTL clones also had specific cytotoxic activity against HLA-A * 2402-positive pancreatic cancer cells that endogenously expressed mesothelin. These results indicate that the mesothelin-10-5 peptide is a novel HLA-A * 2402 restricted CTL epitope and that it is a promising candidate target for antigen-specific immunotherapy against pancreatic cancers.