The shot, a therapeutic vaccine, 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, or CIN. “There are very few products trying to cure women who already have an HPV infection;” says Diane Harper, M.D., M.P.H., M.S., professor of family medicine and obstetrics and gynecology at Michigan Medicine. “It’s very exciting. This is the first time we’ve seen something with this success rate that is relatively easy to implement.”
Cervical precancerous lesions are divided into three grades of severity: CIN 1 lesions generally clear up on their own. CIN 2 lesions often clear up on their own; but can also progress to CIN 3 lesions. CIN 3 is the most severe. It’s a very slow-growing disease; though: fewer than half of CIN 3 lesions will have become cancer within 30 years.
“But we have no way to determine which women with CIN 3 will progress to cancer and which women will not. So we treat all women with CIN 2 or 3 as if they are likely to develop cancer;” Harper says. The study enrolled 192 women diagnosed with CIN2 or CIN3; randomizing 129 to receive the vaccine and 63 to receive a placebo. Women were given three shots in their thigh, one per week for three weeks. Six months later; the women were treated with standard surgical procedures for CIN 2/3 and the removed tissue was examined.
Women who receive the vaccine were more than twice as likely as those who receive placebo to see their CIN eliminate regardless of the type of HPV infection. The results are most striking in the more-severe CIN3: at least 15: and as much as 36: of those who got the vaccine see their CIN3 eliminate; while none of the women in the placebo group did.
Researchers follow the participants for another two and a half years after surgery; the longest any study has follow women in these trials. They shows that long-term follow-up was better for those who receive vaccine over placebo, with more women in the vaccine group remaining completely clear of HPV. The study is publish in Gynecologic Oncology.
Harper notes that the therapeutic vaccine; call Tipapkinogen Sovacivec, or TS, is completely different from Gardasil9, the vaccine given to prevent HPV infection. While Gardasil9 prevents HPV infection from occurring; TS clears tissue already infect with HPV. CIN2 and CIN3 are always caused by high-risk HPV infections.
Developing cervical cancer
The typical treatment procedure for CIN2 or CIN3 involves removing a cone-shaped piece of the cervix, called a LEEP or a cone. This results in scarring and a shortened cervix, which can cause problems during childbirth and lead to increased risk of caesarean section. In addition; women who have this procedure have a very high risk of developing cervical cancer over the next 20 years if they do not continue to be screened.
“The surgical procedure removes all the tissue that is head towards cancer, but it doesn’t remove all the HPV. You’re not home-free. You still have HPV,” says Harper, an internationally recognized HPV researcher and member of the University of Michigan Rogel Cancer Center and senior associate director of the Michigan Institute of Clinical and Health Research (MICHR).