Abstract LB-235: Therapeutic human papillomavirus vaccine design based on epitopes identified on the tumor cell surface by mass spectrometry

Abstract

Abstract Detailed knowledge about T cell epitopes, which are bona fide presented on the surface of human papillomavirus (HPV)-transformed cells, is essential for rational design of therapeutic HPV vaccines. HPV affects the cellular antigen processing machinery, thus not every epitope derived from viral proteins is presented on human leukocyte antigen (HLA) molecules. Even the presented epitopes are displayed in low abundance. In this study, we developed a highly sensitive nano-UPLC-ESI-MS3 multiple-reaction monitoring mass spectrometry (MS) approach for direct detection of low-abundant epitopes on the cell surface. Several web-based prediction algorithms were used to predict prospective epitopes from the HPV16 E6 and E7 proteins. These candidate epitopes were tested for actual HLA binding in cellular binding assays. The presence of binding peptides on HPV16-transformed cells was analyzed by our MS technology. Immunogenicity of candidate peptides was assessed in vitro with short-term and long-term T cell line experiments, generated from peripheral blood mononuclear cells of healthy donors, and in vivo for a selected HLA-A2-restricted epitope in HLA-A2/DR-1 transgenic mice. To ensure >95% population coverage, prospective HPV epitopes were predicted for the HLA supertypes HLA-A1, A2, A3, A11, A24, B7, and B15. Close to 500 peptides were tested in competition-based binding assays and multiple novel binders were identified. MS epitope detection was first established for HLA-A2 epitopes, and is now extended to the other supertypes. In the immunogenicity assays, several peptides induced robust IFN-γ responses. In conclusion, several new HPV16 E6 and E7 epitopes were identified and validated in this study. They represent promising candidates for inclusion into a therapeutic HPV vaccine. Validated epitopes are the basis of rational therapeutic vaccine design and are also important for immunomonitoring purposes. Citation Format: Stephanie Hoppe, Renata Blatnik, Julia P. Schessner, Lisa Dressler, Alina Steinbach, Jan Winter, Martin Wuehl, Alexandra Klevenz, Hadeel Khallouf, Angelika B. Riemer. Therapeutic human papillomavirus vaccine design based on epitopes identified on the tumor cell surface by mass spectrometry. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-235. doi:10.1158/1538-7445.AM2015-LB-235