Self-amplifying mRNA nanovaccine encoding GM-CSF-fused HPV16 E7 enhances immunogenicity and therapeutic efficacy against cervical cancer.

Cervical cancer, driven by the malignant transformation of keratinocytes via the human papillomavirus (HPV) E7 oncoprotein, remains a significant global health challenge. In this study, we developed an alphavirus-based self-amplifying mRNA (saRNA) vaccine encoding either a genetically engineered HPV16 E7 gene or a fusion of granulocyte-macrophage colony-stimulating factor (GM-CSF) with HPV16 E7, both encapsulated in self-assembling liposome-protamine-RNA (LPR) nanoparticles. SaRNA represents a promising vaccine platform due to its intrinsic ability to amplify and prolong antigen expression, offering a substantial advantage over conventional mRNA approaches. Intramuscular administration of LPR-saRNA-GM-CSF-E7 in mice triggered robust innate immune responses and activated antigen-presenting cells in the draining lymph nodes, leading to enhanced T-cell effector functions. The LPR-saRNA-GM-CSF-E7 nanovaccine more effectively reprogrammed the tumor microenvironment by reducing immunosuppressive cell populations and increasing Th1 cytokine expression compared to LPR-saRNA-E7. Importantly, in vivo cytotoxic T lymphocyte (CTL) assays demonstrated that LPR-saRNA-GM-CSF-E7 vaccination elicited potent E7-specific CD8+ T cell cytolytic activity. Furthermore, this nanovaccine significantly delayed tumor progression and prolonged survival in TC-1 tumor-bearing mice, underscoring its superior efficacy over the LPR-saRNA nanovaccine encoding only E7. These findings highlight the potential of the LPR-saRNA-GM-CSF-E7 nanovaccine as a novel and promising therapeutic strategy for cervical cancer immunotherapy.