Toll-Like receptor 3 (TLR3) agonists in a multi-peptide vaccine for TFDP3 expressing cancers
Authors: Neta Genilda Castro de Omena , Junior Jose Wilson Batista da Silva , Rocha Rodger Marcel Lima , Duarte Ana Kelly da Silva Fernandes , Gomes Emisael Stenio Batista , Zanchi Fernando Berton , Marques Carolinne de Sales , Fraga Carlos Alberto de Carvalho 
Published: October 2024

The increase in cancer incidence and mortality worldwide has demonstrated the need for investment in more effective anti-tumor therapies. Given the complexity of the mechanisms that lead to resistance to anti-tumor treatments, target therapies are promising approaches. Cancer testicular antigens (CTAs) are therapeutic targets with the potential to be explored, as they are not expressed in normal cells and are expressed in tumor cells, as is the case with TFDP3, expressed in triple-negative breast cancer, prostate cancer, childhood T-cell lymphoblastic leukemia and hepatocellular carcinoma. The objective proposed in this work is the in silicoprediction of a multi-epitope tumor antigen vaccine candidate from TFDP3. The epitopes were screened using immunoinformatics tools that identified the antigenic epitopes that interacted with B lymphocytes, CD4+, T lymphocytes, and CD8+ T lymphocytes. The population coverage of the epitopes on CD4+ T lymphocytes and CD8+ T lymphocytes was then assessed. From the epitopes of B lymphocytes, CD4+ T lymphocytes, and CD8+ T lymphocytes, 3 epitopes from each were selected to make up the multi-epitope vaccine determined by antigenicity, allergenicity, toxicity, IFN-γ induction, and population coverage. In addition to the epitopes, the vaccine was made up of an adjuvant and ligands that ensured certain properties of the epitopes, their processing in MHC class I biosynthesis, and post-translational modifications. The vaccine's homology with other proteins was assessed using the NCBI BLASTp server. The physicochemical parameters, antigenicity, allergenicity, and toxicity were then evaluated. The secondary structure and tertiary structure were determined using servers that use neural networks, as well as the quality parameters associated with the structure. In the tertiary structure, the linear and discontinuous epitopes of B lymphocytes were determined using the IEDB server. From there, the interaction by molecular docking with Toll-like receptors and molecular dynamics was evaluated to assess the stability of the multi-epitope vaccine in a biological system. Finally, the in silico assessment of the possibility of cloning the multi-epitope vaccine and its immune response after 1 and 3 successive administrations was also evaluated. Epitopes that interact with antigenic, non-allergenic, and non-toxic B lymphocytes, CD4+ T lymphocytes, and CD8+ T lymphocytes were identified. About CD4+ T lymphocytes, 4 epitopes, as well as being antigenic, non-allergenic, and non-toxic, are inducers of IFN-γ. In the population coverage, the MHC class I and MHC class II epitopes had 93.55% coverage worldwide. The multi-epitope vaccine has biologically favorable physicochemical parameters, low homology with human proteins, secondary and tertiary conformation compatible with native protein structures. It also has interactions with TLR-2 and TLR-3, with TLR-3 being the interaction that in a biological system guarantees the greatest stability of the multi-epitope vaccine. In addition, in silico analyses have shown that the multi-epitope vaccine can be cloned and develop a more robust and prolonged immune response when submitted to 3 administrations. Therefore, the multi-epitope vaccine designed from the testicular cancer antigen TFDP3 showed in silico several promising biological properties and responses so that in vitro and in vivo studies can be invested and the future application of this vaccine in the treatment of cancer types that express this CTA.