A experimental human papilloma virus (HPV) vaccine may be capable of killing cervical cancer cells, according to an early clinical study of the vaccine published in the 10 October issue of the journal Science Translational Medicine.
The VGX-3100 vaccine differs from preventive HPV vaccines, such as Gardasil and Cervarix, which protect against HPV infection. VGX-3100 is a therapeutic vaccine designed to combat existing cervical cancer and control pre-cancerous lesions. It works by stimulating the body’s immune system to target HPV-infected cells that are known to cause cervical cancer.
The vaccine works specifically against cancers caused by HPV types 16 and 18. Researchers at Inovio Pharmaceuticals now show that cancer-destroying immune cells called CD8+ T cells are induced after vaccination with VGX-3100. Their study suggests that VGX-3100 could potentially spur cancer regression in individuals already infected with HPV.
“We show for the first time that we can induce killer T-cell responses…which are believed to be critical for a therapeutic vaccine and clearance of HPV infected cells,” said Niranjan Sardesai, senior author of the study and chief operating officer at Inovio Pharmaceuticals.
In the clinical trial, 18 women previously treated for cervical neoplasia—a precursor to cervical cancer—were given VGX-3100 by electroporation, a small electric pulse that accompanies injection. The authors observed that delivering the vaccine with electroporation induces a strong HPV-specific immune response in previously infected individuals. Women who received the vaccine reported only minor side effects at the range of doses tested.
The vaccine works in a manner similar to gene therapy, by inserting a piece of DNA which codes for a specific protein into a patient’s cells. This produces another protein that commands the immune system to attack HPV-infected cells.
Cervical cancer is the second most common cancer among women worldwide, and is the only cancer known to be caused by a viral infection. Nearly 75% of cervical cancer cases are caused by the HPV 16 and 18 types targeted by the therapeutic vaccine.
“In addition to continuing to do the efficacy studies with the vaccine for the treatment of cervical dysplasia, we will be expanding our research into targeting HPV associated cancers such as cervical, head and neck, and anogenital cancers” Sardesai said. “The broader goal for the program is to target HPV-associated disease.”
Read the abstract, “Immunotherapy Against HPV16/18 Generates Potent TH1 and Cytotoxic Cellular Immune Responses,” by M.L. Bagarazzi and colleagues.