Design, preparation, and antitumor activity of fusion protein vaccine based on tumor antigen PBK

PBK is a cancer/testis antigen that exhibits absent expression in various normal human tissues, but undergoes aberrant overexpression upon cellular transformation, thereby promoting the initiation, metastasis and even drug resistance of cancer. Consequently, it represents a novel target for tumor immunotherapy. In this study, PBK-Nitrath, a protein vaccine specifically designed to target PBK by fusing nitrated T epitope with the PBK protein was developed, using the IFN-γ ELISpot method to evaluate the activation level of PBK antigen-specific T cells in the spleen of immunized mice, and conducting in vitro cytotoxicity T cell killing efficacy test to evaluate the killing ability against H22 hepatic carcinoma cells; the anti-tumor activity was evaluated using a H22 hepatic carcinoma subcutaneous transplantation tumor model, and the differentiation of peripheral blood and spleen T lymphocytes and tumor immune infiltration were analyzed by flow cytometry. Results showed that PBK-Nitrath could efficiently induce the activation of antigen-specific T cells against PBK while enhancing cytotoxic T lymphocyte-mediated killing capacity, significantly impede hepatic carcinoma progression in mice and increase the ratio of CD8⁺CD107a⁺ T cells within peripheral blood and spleen, and facilitate tumor lymphocyte infiltration. Our findings reveal the potential utility of PBK-Nitrath as an effective candidate for tumor vaccine.