Abstract 1690: Epitope-minigenes for optimal induction of the immune response against tumor associated antigens and neoantigens

We have recently established a workflow that allows the identification of T cell epitopes within Tumor Associated Antigens (TAAs) and the construction of genetic cancer vaccine based on the use of minigenes. The T-cell epitope in silico prediction approach is based on three criteria: 1) binding to MHC Class I alleles; 2) uniqueness to the antigen of interest; 3) increased likelihood of natural processing. The combination of in silico prediction and a biochemical binding/stability assay resulted in an accurate identification of novel TAA-derived epitopes. Predicted T cell epitopes were connected by furin sensitive linkers and linked to human tissue plasminogen activator (TPA) signal and E. Coli enterotoxin B subunit, to construct an optimal minigene scaffold used as vaccine candidate. The present study was aimed at evaluating HER2/neu and hTERT (telomerase) minigenes with the same technology platform. First of all, minigenes delivered via Electro Gene Transfer (DNA-EGT) were more immunogenic than genetic vectors encoding the full-length protein or peptides injected subcutaneously and they were able to break immune tolerance in wild type and HLA-A0201 transgenic mice. Moreover, this technology applied to epitopes selected within Mutated Tumor Antigens results in strong immunogenicity and significant antitumor effects in mouse models. In conclusion, we show that minigenes delivered via DNA-EGT and based on predicted and/or experimentally identified epitopes are powerful tools to induce immune responses and combat cancer. Combination studies of minigenes with peptide vaccination, chemotherapy and immune checkpoint blockade may define new therapeutic opportunities for cancer patients. Citation Format: Silvio Bandini, Laura Luberto, Fabio Palombo, Giuseppe Roscilli, Emanuele Marra, Gennaro Ciliberto, Luigi Aurisicchio. Epitope-minigenes for optimal induction of the immune response against tumor associated antigens and neoantigens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1690. doi:10.1158/1538-7445.AM2017-1690