A genetically engineered vaccine eradicated high-grade precancerous cervical lesions in almost half of women participating in a clinical trial at Johns Hopkins University in the US.

Not to be confused with preventative vaccines such as Gardasil, the new treatment could provide a nonsurgical solution for existing precancerous lesions caused by the human papillomavirus (HPV) that's typically spread through sexual contact.

"Every standard therapeutic option for women with these lesions destroys part of the cervix," says first author Cornelia Trimble, M.D. of Johns Hopkins, "Which is particularly relevant for women of childbearing age, who may then be at risk for preterm birth due to a weakened cervix."

Women aged 40 or younger are the most likely to develop high-grade cervical lesions, and existing solutions are invasive and include surgery, freezing or laser treatment, says Dr. Trimble.

Less threatening lesions -- referred to as low-grade dysplasia -- do not require immediate removal, but doctors monitor them in the hopes they will regress, because until they do, they still pose some degree of risk.

The brainchild of University of Pennsylvania scientist David Weiner, PhD, the vaccine is designed to instill recognition of precancerous and cancerous cells in the immune system.

The research team spent two years recruiting 167 women between the ages of 18 and 55, all of whom were newly diagnosed with high-grade precancerous cervical lesions.

When recruiting was complete in 2013, the women received either three doses of the vaccine or placebo injections over the course of 12 weeks across 36 hospitals and private gynecology practices in the US and six additional countries.

Following each injection, the women were given a small electric pulse at the injection site, causing cells in the vicinity to open their pores and thereby increasing the chances of the vaccine being picked up by the immune system.

Fifty-five, or 48.2 percent of the 114 women who received at least one dose saw their lesions regress or convert to low-grade dysplasia, according to the paper.

For the 107 women who received all three injections, HPV was subsequently undetectable in 56 of them, say the researchers.

"In many of these women, the vaccine not only made their lesions disappear, but it also cleared the virus from their cervix," says Dr. Trimble. "In most unvaccinated patients whose lesions went away, the virus was still present, and many still had low-grade lesions."

Meanwhile, 12, or 30 percent of the 40 women given at least one placebo injection experienced regression or conversion of their lesions.

Thirty-six of these women received all three placebo doses and 11 of them, or 30.6 percent saw their lesions regress.

The vaccine is made by Inovio Pharmaceuticals, Inc., who funded the trial and whose employees co-authored Dr. Trimble's paper, published in the Lancet.