Development and assessment of a peptide vaccine against ovarian cancer utilizing nanoliposomes loaded with P53, WT1, and CA125 epitopes

This study aimed to design, synthesize, and evaluate a peptide vaccine based on nanoliposomes loading multi-epitopes (PVNLME) of P53, WT1, and CA125. We selected the best epitope for each targeted protein and then, PVNLME was synthesized and characterized. Subsequently, BALB/c mice were randomly divided into two groups receiving 10 mg/ml or 100 mg/ml of PVNLME. Then, 100 µl of the vaccine were injected into each mouse every seven days for three consecutive weeks. In the fourth week, blood samples were taken, and both antibody titer and the serum level of different cytokines were measured. To further investigate, each mouse's serum sample was exposed to the OVCAR3 cell line. Subsequently, BAX to BCL2 gene expression ratio, cell viability, and apoptosis were evaluated. Finally, the efficacy of the peptide vaccine was analyzed in humanized PDX model mice. Based on Bioinformatics analysis, a merged peptide EENLRKKGEPHHELPPKKKKCKTCQRKFSRSDHLKTKKKDTTPSMTTSHGAESSS was selected as a multi-epitope peptide. We found that the size distribution of PVNLME was 72-198 nm with a mean size of 112 nm, zeta potential of + 30 mV, and 96% peptide loading. The level of cytokines and the titer of antibodies increased with increasing doses of PVNLME. Furthermore, we showed that this vaccine can increase the ratio expression of BAX /BCL2, which promotes apoptosis. Also, there was a decrease in cell viability and an increase in apoptosis rate in both doses and exposure times. Following the administration of this multi-epitope vaccine in PDX humanized mice, a notable reduction in the tumor volume was observed.