GPC3 _127–136 -HSP70 mRNA Nanovaccine in Combination with Anti-PD-L1 Therapy Elicits Robust T-Cell-Mediated Immunity against Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) remains a clinically challenging malignancy, and it is imperative to develop novel therapeutic strategies for HCC treatment. In this study, we developed a novel mRNA-based nanovaccine (SK-mRNA) targeting the tumor-associated antigen glypican-3 (GPC3). The SK-mRNA vaccine consists of <i>in vitro</i>-transcribed mRNA encoding 3 × GPC3_127-136 CTL epitopes fused with HSP70, which self-assembles with the cationic peptide SP94-GGG-K18 to form a uniform spherical nanostructure. This nanovaccine facilitates the targeted delivery of mRNA to tumors via SP94 binding with its cognate receptor on tumor cells, enabling the expression and secretion of the 3 × GPC3_127-136-HSP70 fusion protein. Subsequently, dendritic cells internalize this protein through its receptors on dendritic cells, leading to the presentation of CTL epitope GPC3_127-136 to T cells. Experimental vaccination elicited robust antigen-specific T-cell responses, as evidenced by the significant increase in CD8⁺ T cells observed in both spleens and tumors, along with enhanced IFN-γ secretion in response to the GPC3_127-136 peptide. The combination of SK-mRNA nanovaccine with anti-PD-L1 immunotherapy exhibited potent synergistic antitumor effects. These findings collectively suggest that SK-mRNA nanovaccines can effectively stimulate immune responses and synergize with immune checkpoint blockade therapies to mediate powerful antitumor effects, offering a promising strategy for the effective treatment of HCC.