Immune responses against tumour‐associated antigen‐derived cytotoxic T lymphocyte epitopes in cholangiocarcinoma patients

BACKGROUND & AIMS:Immunotherapy is a promising treatment option for cholangiocarcinoma. We compared cytotoxic T lymphocyte (CTL) responses against several tumour-associated antigen (TAA)-derived epitopes in cholangiocarcinoma patients to identify candidate epitopes for immunotherapy. METHODS:Twenty-six TAAs were selected, and the expression of TAAs in 6 cholangiocarcinoma cell lines and 9 specimens were measured using real-time polymerase chain reaction (PCR). CTL responses against 38 TAA-derived epitopes were measured using samples from 26 cholangiocarcinoma patients by interferon-γ enzyme linked immunospot (ELISPOT)-assay. RESULTS:Most TAAs were expressed in cholangiocarcinoma cell lines and specimens in PCR. Epitopes that stimulated a specific immuneresponse were defined as those that elicited a CTL response in more than 3 patients and little response in healthy volunteers, as measured by ELISPOT-assay. Based on these criteria, there were 18 epitopes that stimulated specific immuneresponses: squamous cell carcinoma antigen recognized by T cells (SART)1690 , P53161 , multidrug resistance-associated protein (MRP)3503 , Survivin2B80 , melanoma-associated antigen(MAGE)-A4143 , receptor tyrosine kinase ErbB-2/neu ( Her2/neu)63 , Wilms tumour (WT1)235 , WT1417 , β-catenin29 , carcinoembryonic antigen (CEA)268 , CEA652 , epithelial cell adhesion molecule(EpCAM)173 , enhancer of zestehomolog (EZH)2291 , mucin 5AC (MUC5AC)716 , glypican-3 (GPC3)298 and kinesinfamily member 20A (KIF20A)66 . Furthermore, the absolute number of lymphocytes in peripheral blood was significantly correlated with the TAA-specific response. Lastly, the overall survival was significantly prolonged in patients with 2 or more TAA-specific CTL responses compared with none to one. CONCLUSIONS:These results demonstrated several TAAs may be promising for immunotherapy for cholangiocarcinoma, and patients with high lymphocyte counts may benefit more from immunotherapy.