HPV and Therapeutic Vaccines: Where are We in 2010?

The discovery of human papillomavirus (HPV) as a necessary etiological factor for cervical cancer has spurred the development of preventive and therapeutic HPV vaccines for the control of HPV-associated malignancies including cervical, vulvar, vaginal, and a subset of head and neck cancers. The commercial preventive HPV vaccines, Gardasil and Cervarix, use HPV virus-like particles to generate neutralizing antibodies against HPV major capsid protein L1. However, they do not exert therapeutic effects on existing lesions and are unlikely to have an immediate impact on the prevalence of cervical cancer due to their cost and limited availability in developing countries, which account for more than 80% of cervical cancers. Thus, there is an urgent need for therapeutic HPV vaccines. Therapeutic HPV vaccines can eliminate preexisting lesions and infections by generating cellular immunity against HPV-infected cells. HPV E6 and E7 oncoproteins represent ideal targets for therapeutic intervention because of their constitutive expression in HPV-associated tumors and their crucial role in the induction and maintenance of HPV-associated disease. This review discusses the current progress of various therapeutic HPV vaccine approaches, including live vector-based, peptide/protein-based, nucleic acid-based and cell-based vaccines targeting E6 and/or E7 antigens, and their future prospects for the control of HPV-associated malignancies.