Targeted degradation of the HPV oncoprotein E6 reduces tumor burden in cervical cancer.

Human papillomavirus (HPV) remains a global health burden, yet there are no targeted therapies for HPV-related cancers. The HPV E6 protein is essential for tumorigenesis and immune evasion, making it an attractive target for antiviral drug development. In this study, we developed an E6-targeting proteolysis targeting chimera (PROTAC) that inhibits the growth of HPV tumors. To develop E6 antagonists, we generated a panel of nanobodies targeting HPV16 E6 protein. Nanobody A5 was fused to Von Hippel-Lindau protein to generate a PROTAC that degrades E6 (PROTAC). Mutational rescue experiments validated E6 degradation via the CRL2 E3 ligase. To deliver PROTAC, we used a clinically viable DNA vaccine, which offers the advantages of localized PROTAC expression and low production costs compared to protein- or viral-based therapies. Intralesional administration of the PROTAC reduced tumor burden in an immunocompetent mouse model of HPV cancer. The PROTAC inhibitory effect was abrogated by CD4 and CD8 T cell depletion, indicating that the antitumor function of the PROTAC relies in part on host immune responses. These results demonstrate that E6 degradation inhibits its oncogenic function and stimulates an immune response in HPV tumors, opening new opportunities for virus-specific therapies in the treatment of HPV-related cancers.