A new type of cervical cancer vaccine has shown early promise as a potential treatment for pre-cancerous changes in the cervix, researchers for the vaccine maker said. Instead of preventing infections caused by certain strains of the human papillomavirus or HPV, as is the aim of Merck's Gardasil and GlaxoSmithKline's Cervarix vaccine, the Inovio vaccine developed by Inovio Pharmaceuticals is designed to train the immune system to kill cells that spur cancer growth in women who are already infected. Cervical cancer is the second most common cancer among women globally, causing 493,000 new cases and 274,000 deaths each year. About 10 to 25 per cent of women who develop moderate to severe pre-cancerous lesions in their cervix, known as cervical intraepithelial neoplasia, are able to clear them on their own. "It was not clear why that happens," said Joseph Kim, chief executive of Inovio Pharmaceuticals, which funded the study. But many of these women tend to have higher levels of immune system cells known as T cells against two HPV-specific, cancer-causing genes known as E6 and E7 oncogenes. The company set out to develop a vaccine to train a patient's immune system to make large quantities of these cells which could specifically target and kill these oncogenes. "That is what this study has shown," Kim said of research published in the journal Science Translational Medicine . The team studied the effects of three injections of the vaccine, dubbed VGX-3100, in 18 women whose cancers had already been treated surgically. The vaccine produced potent T cells in 14 of the 18 women, which lasted for two years. "These T cells were not only abundant in number; they were able to do what they were designed to do. They were able to seek out and kill the target cells," Kim said. The study found no major side effects in any of the three doses tested. Lab tests showed more than 90 per cent of the women who responded developed T cells which were able to kill the target cells, suggesting it might work as a cancer treatment.