Exploring the Immunogenicity of Noncanonical HLA-I Tumor Ligands Identified through Proteogenomics

Purpose: Tumor antigens are central to antitumor immunity. Recent evidence suggests that peptides from noncanonical (nonC) aberrantly translated proteins can be presented on HLA-I by tumor cells. Here, we investigated the immunogenicity of nonC tumor HLA-I ligands (nonC-TL) to better understand their contribution to cancer immunosurveillance and their therapeutic applicability. Experimental Design: Peptides presented on HLA-I were iden-tified in 9 patient-derived tumor cell lines from melanoma, gyneco-logic, and head and neck cancer through proteogenomics. A total of 507 candidate tumor antigens, including nonC-TL, neoantigens, cancer-germline, or melanocyte differentiation antigens, were tested for T-cell recognition of preexisting responses in patients with cancer. Donor peripheral blood lymphocytes (PBL) were in vitro sensitized against 170 selected nonC-TL to isolate antigen-specific T-cell recep-tors (TCR) and evaluate their therapeutic potential.Rudolf Virchow Center, Center for Integrative and Transla- tional Bioimaging, Julius-Maximilians-University Wueurorzburg, Wueurorzburg, Germany