A recent phase I/II clinical trial in patients with high-grade squamous intraepithelial lesion associated with HPV16 provided DNA plasmid expressing a mutated nonfunctional E7 incapable of binding retinoblastoma protein, with no transforming activity, linked to HSP70. A signal sequence was also attached to the hybrid antigen which results in secretion of the linked E7 antigen [67] . E7 HPV antigen as well as E6 antigen are essential for transformation and are coexpressed in HPV-associated lesions hence they represent ideal targets for the development of HPV therapeutic vaccines.