Identification and analysis of tumor-associated antigens in triple-negative breast cancer (TNBC)
Heimes A.-S.1, Versantvoort C.2, Hensen S.3, Bolz S.2, Rösler T.2, Brenner W.1, Hasenburg A.1, Sahin U.2,3, Rothermel A.2,3, Schmidt M.1
1Universitätsmedizin Mainz, Klinik und Poliklinik für Geburtshilfe und Frauengesundheit, Mainz, Deutschland, 2TRON Translationale Onkologie an der Universitätsmedizin der Johannes Gutenberg-Universität Mainz, Mainz, Deutschland, 3BioNTech, Mainz, Deutschland

Background: A high level of tumor-infiltrating plasma cells in TNBC may be an indication for immunogenic potential, which could be used as a valuable potential therapeutic tool. To identify potential target structures of the humoral immune response, we analyzed the antibody signatures in plasma from TNBC patients with a high level of tumor infiltrating plasma cells compared to plasma samples of TNBC patients with low plasma cell infiltration in the primary tumor.
Methods: In a first step we classified the samples in a group with high plasma cell infiltration and low plasma cell infiltration. Plasma samples of 5 healthy donors served as negative control group. Phage display screening was performed using existing phage libraries, which contained about 1,5 million peptides followed by Next Generation sequencing (NGS). After biostatistical analysis, results of potential antigens were validated using enzyme-linked immunosorbent assay (ELISA). In a next step the expression of the identified antigens was evaluated in the corresponding tumor slides using immunohistochemistry.
Results: Eleven samples were revealed with a high plasma cell infiltration, whereas 24 samples showed a low plasma cell infiltration. After phage display screening, NGS and biostatistical analysis a total of 99 potential peptide candidates could be identified. Top peptide candidates were further validated using ELISA, in which several targets showed a good correlation to NGS. However, upon analysis of additional healthy donors, only two targets, KDM5B and CBX5, could be identified to discriminate between healthy and diseased. The results of immunohistochemistry were still pending at the time of abstract submission.