Persistent infection with high-risk human papillomavirus (HPV) drives the development of cervical and other anogenital cancers, with limited therapeutic options for early-stage disease and precancerous lesions. There is a critical unmet need for effective therapeutic vaccines capable of inducing durable immune responses to eliminate early tumor cells and prevent disease progression. In this study, we developed lipid nanoparticle (LNP)-formulated mRNA vaccines encoding HPV16 E6 and E7 oncoproteins and evaluated their efficacy in a murine model using a low tumor inoculum (5,000-10,000 TC-1 cells) to represent a low tumor burden, early-intervention setting. E7 mRNA/LNP induced stronger antigen-specific T cell responses than E6 when administered intramuscularly at a low dose (1 µg). In therapeutic settings, initiated 3 d after tumor implantation, either as a single 10 µg dose or a two-dose regimen (10 µg followed by 5 µg, 6 d apart), E7 vaccination elicited robust T cell responses, significant tumor regression, and undetectable HPV16 E6/E7 DNA, outperforming E6 across regimens. In the preventive setting, administration of two 5 µg doses of HPV16 E7 prevented tumor establishment following TC-1 cell inoculation. Importantly, E7 vaccination induced durable immune memory, as demonstrated by sustained tumor protection and undetectable HPV E6/E7 DNA upon rechallenge at 5 months. These findings highlight the potential of HPV16 E7 mRNA/LNP as a therapeutic vaccine targeting low tumor burden HPV-associated disease and support further clinical development. A multivalent mRNA vaccine targeting multiple high-risk HPV genotypes is currently under development.
