Experimental shot totally clears HPV in one-third of cervical cancer precursors

4 Apr 2019

Image: © Louise /Stock.adobe.com

Scientists are excited by a new experimental HPV vaccine that has totally eliminated cervical cancer precursors in one-third of cases.

While still early days, researchers from the University of Michigan have revealed a major breakthrough that could one day change the lives of women diagnosed with human papillomavirus (HPV). The virus is a group of more than 150 related viruses that could lead to the development of cervical, vaginal and vulvar cancers.

In a paper published to Gynecologic Oncology, the researchers described a new immune-based therapy designed to treat precancers in the cervix. They said they were able to completely eliminate both the lesion and underlying HPV in one-third of women who took part in a medical trial.

Future Human

The vaccine shot injects a specific protein that triggers the immune system to attack high-risk HPV types responsible for nearly all cervical cancer precursors, known as cervical intraepithelial neoplasia (CIN).

“There are very few products trying to cure women who already have an HPV infection,” said Diane Harper, a professor of family medicine, and obstetrics and gynaecology 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, ranging from CIN 1, which tends to clear up on its own, to CIN 2, which can clear itself but could progress to CIN 3. CIN 3 is the most severe grade, resulting in a slow-growing disease that could become cancerous over a period of 30 years.

However, because there is currently no way to know which women will progress to CIN 3, all women diagnosed with CIN 2 are treated as if they have the most severe grade.

Black and white close-up of a spherical HPV.

Electron micrograph of a negatively stained HPV, which occurs in human warts. Image: Public domain

Long-term success

This latest study enrolled 192 women diagnosed with CIN 2 or CIN 3, with a random selection of 129 women receiving the new vaccine and 63 given a placebo. A course of three shots was injected into each patient’s thigh, once a week for a period of three weeks.

Six months later, the women underwent surgery that removed the lesions. An examination of the tissue found that those who received the vaccine were twice as likely to see their CIN eliminated – regardless of the HPV infection – compared with those who just had a placebo.

In the most severe cases of CIN 3, at least 15pc and as much as 36pc of those who got the vaccine had their CIN 3 eliminated, compared with zero in the placebo group. The participants were tracked over the next two-and-a-half years and it was shown that those with the vaccine were still clear of HPV.

The researchers stressed that the vaccine, called Tipapkinogen Sovacivec (TS), is completely different from Gardasil 9, the vaccine given to prevent HPV infection. While Gardasil 9 prevents HPV infection from occurring, TS clears tissue already infected with HPV. CIN 2 and CIN 3 are always caused by high-risk HPV infections.

The researchers noted that those who received the vaccine reported sometimes-severe reactions at the injection site. This was expected, they said, as it is designed to trigger the immune system and can result in inflamed skin.

Now, they hope to undergo further trials before seeking approval to release it to the public.

Colm Gorey was a senior journalist with Silicon Republic