A new experimental immune-based vaccine has cleared human papillomavirus (HPV) in a third of women with cervical cancer precursors, according to clinical trial results.

The therapeutic vaccine, called Tipapkinogen Sovacivec (TS), injects a specific protein that triggers an immune system response to attack high-risk HPV types that cause nearly all cervical cancer precursors, known as cervical intraepithelial neoplasia (CIN). HPV is a common sexually transmitted infection and causes warts in the body.

The vaccine eliminated both precancerous skin growth in the cervix, and underlying HPV infection in a third of women enrolled in the clinical trial, according to the report in the journal Gynecologic Oncology. "There are few products trying to cure women with an HPV infection," said Diane Harper, professor at the University of Michigan. "It's exciting. This is the first time we've seen something with this success rate and that is relatively easy to implement," Harper said.

The study enrolled 192 women, diagnosed with precancerous skin growths, randomising 129 to receive the vaccine and 63, placebo. Women were given three shots in thighs, one per week. Six months later, the women were treated with standard surgical procedures and the removed tissue was examined. As many as 15-36 per cent of those who were vaccinated saw their more severe precancerous skin growths eliminated, but none in the placebo group.

While "the surgical procedure removes all the tissue that is headed towards cancer, it does not remove all the HPV. You still have HPV", Harper said, adding the new vaccine "actually treats the cause of the disease, which is HPV". Harper also noted TS is different from Gardasil9, the vaccine given to prevent HPV infection. While Gardasil9 prevents HPV infection from occurring, TS clears tissue infected with it. The researchers envision testing TS for several other types of cancer, including head, neck and anal cancer, that are linked to HPV.