Base editing-mediated induction of stop codons in HPV18 E6/E7 for cervical cancer therapy

Persistent infection with high-risk human papillomaviruses (hrHPVs) is a primary driver of cervical carcinogenesis, with the viral oncogenes E6 and E7 playing pivotal roles. Conventional nuclease-based gene-editing strategies are limited by genome-wide off-target effects and genomic perturbations associated with double-strand breaks (DSBs). To address these challenges, we developed BE-PLUS-iSTOP, a DSB-free cytosine base-editing strategy designed to inactivate HPV18 E6/E7 through the precise installation of premature termination codons (PTCs). This strategy achieved high on-target editing efficiencies (51.00 ± 2.94% for E6 and 26.33 ± 2.62% for E7) with minimal indel formation (undetectable for E6 and < 0.1% for E7). Functional analyses demonstrated that BE-PLUS-iSTOP effectively reduced E6/E7 protein expression, resulting in robust suppression of malignant phenotypes in HPV18-positive cervical cancer cells. In a subcutaneous xenograft mouse model, intratumoral delivery of BE-PLUS-iSTOP induced extensive tumor necrosis and significantly suppressed tumor growth, with no overt systemic toxicity under the tested conditions. Collectively, these findings establish BE-PLUS-iSTOP as a precise and efficient etiology-directed therapeutic strategy for HPV18-positive cervical cancer, supporting its potential for further translational development and broadening the scope of antiviral gene therapy.