A vaccine for women already harboring human papillomavirus (HPV) appeared to fight cervical cancer in a small study.

Most cervical cancers are caused by HPV infection. Unlike prophylactic vaccines that prevent the acquisition of HPV, VGX-3100 is a therapeutic vaccine designed to combat existing cervical cancer and control precancerous lesions, specifically those caused by HPV serotypes 16 and 18.

In a recent phase 1 study, 18 women previously treated for cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3), a precursor to cervical cancer, received an intramuscular three-dose regimen of VGX-3100. The vaccine consists of highly engineered plasmid DNA encoding HPV 16 and HPV 18 E6/E7 antigens, working in a manner similar to that of gene therapy in that it inserts a piece of DNA that codes for a specific protein in the patient’s cells. This produces another protein that directs the immune system to attack HPV-infected cells.

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VGX-3100 delivery was accompanied by electroporation, a small electric pulse. As reported in Science Translational Medicine (2012;4[155]:155ra138), delivering the vaccine with electroporation induced a robust HPV-specific immune response in  previously infected individuals. Only minor side effects were seen at the range of doses tested.

These early results suggest that VGX-3100 could potentially spur cancer regression in individuals already infected with HPV, according to a news release from Science Translational Medicine.