A novel mRNA-based therapeutic vaccine elicits robust anti-tumor immunity against HPV-associated malignancies

Background: Human papillomavirus (HPV) infection is strongly associated with multiple malignancies, primarily driven by the viral oncoproteins E6 and E7, which play a central role in HPV-induced malignant transformation. Although current prophylactic HPV vaccines have shown remarkable efficacy in preventing initial infections, there remains an urgent need for therapeutic vaccines targeting pre-existing HPV infections and HPV-associated malignancies. Methods: T cell activation and proliferation assays were conducted to investigate the mechanistic underpinnings of the vaccine. Additionally, safety was assessed in a PBMC-reconstituted mouse model. Results: compared to control mRNAs lacking co-stimulatory elements. Furthermore, combination therapy with anti-PD-L1 antibody synergistically enhanced the anti-tumor efficacy of TriStim-E6/E7 mRNA. To evaluate clinical translatability, we developed a humanized version (hTriStim-E6/E7) encoding human CD80, 4-1BBL, and CD70 co-stimulatory molecules together with HPV E6/E7 fusion proteins. This humanized construct effectively induced antigen-specific cellular immune responses and suppressed tumor growth in CD28/4-1BB/CD27 triple-humanized mice. Additionally, a "cytokine release storm" experiment using PBMC-reconstituted mice confirmed a favorable safety profile of TriStim-E6/E7 mRNA. Conclusions: These findings collectively demonstrate the promising therapeutic potential of TriStim-E6/E7 mRNA for clinical translation against HPV-associated malignancies.