Abstract 2689: XAGE-1b(GAGED2a) immunity in non-small cell lung cancer

Abstract

Abstract BACKGROUND: Several cancer/testis(CT) antigens such as NY-ESO-1 antigen, etc., have been shown to elicit immune responses in cancer patients spontaneously. Because of their restricted expression in normal tissues and high immunogenicity, CT antigens have been thought to be attractive targets for cancer vaccine. We previously described XAGE-1b (GAGED2a), one of the CT-associated antigens, was predominantly expressed in lung adenocarcinoma by immunohistochemistry using XAGE-1b mAb (clone USO 9-13) and could elicit both humoral and cellular immune response in patients with non-small cell lung cancer (NSCLC). In this study, we established CD4 and CD8 T cell clones from PBMC in XAGE-1b antibody-positive patients and analyzed the antigen recognition. MATERIALS AND METHODS: Sera and PBMCs were obtained from NSCLC patients who visited Kawasaki Medical School Hospital between 2005 and 2010. Antibody response to XAGE-1b was analyzed by ELISA using synthesized XAGE-1b protein. CD4 and CD8 T cell responses against XAGE-1b were examined by IFN-γ ELISA and/or capture assay using 17 16- or 17-mer XAGE-1b-overlapping peptides (OLPs) spanning the entire XAGE-1b protein by FACS in antibody-positive patients. Cytotoxicity was analyzed by bioluminescence assay (GAPDH). RESULTS: Spontaneous CD4 and CD8 T cell responses were also detected in most of the antibody positive patients. Occurrence of antibody response, and CD4 and CD8 T cell responses in XAGE-1b (GAGED2a) antibody positive patients indicated strong immunogenicity of XAGE-1b (GAGED2a) antigen in NSCLC patients. Furthermore, We identified the minimal epitope peptide bound to HLA-DR4.1 and DP5 recognized by CD4 and those bound to HLA-A2, B61 and Cw1 recognized by CD8 T cell clones. CD4 and CD8 T cell clones recognized naturally processed XAGE-1b (GAGED2a) antigen on APC (antigen-presenting cell) and the CD8 T cell clone was stained with the peptide/MHCI tetramer and showed cytotoxicity against XAGE-1b (GAGED2a)-expressing, appropriate HLA class I expressing tumor cell line. CONCLUSION: Our findings indicate validity of XAGE-1b (GAGED2a) for cancer vaccine. Now we plan to global clinical trial of cancer vaccine against XAGE-1b in NSCLC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2689. doi:10.1158/1538-7445.AM2011-2689