A genetically engineered cervical cancer vaccine performed well in a clinical trial, offering hope that many women can one day avoid surgery that short-circuits the disease but threatens their ability to have a baby.
The vaccine eradicated high-grade precancerous cervical lesions in nearly half of women who received it, scientists report.
The goal of the trial was to find nonsurgical ways to treat precancerous lesions caused by human papillomavirus (HPV), which is the most common form of sexually transmitted infection and can lead to cervical cancer, according to the US Centers for Disease Control and Infection.
Cornelia Trimble, professor of gynecology and obstetrics, oncology, and pathology at Johns Hopkins University School of Medicine, says :
“Every standard therapeutic option for women with these lesions destroys part of the cervix, which is particularly relevant for women of childbearing age, who may then be at risk for preterm birth due to a weakened cervix.
A vaccine able to cure precancerous lesions could eventually be one way women can avoid surgery that is invasive and can also harm their fertility.”
The cervix is the lower part of a woman’s uterus. Despite dramatic progress in recent decades, about 12,000 women still develop cervical cancer in the United States each year, and about 4,000 die.
High-grade cervical lesions occur most often in women 40 or younger. Because the lesions can progress to cancer, they are today usually removed by surgery, freezing, or laser treatment. The procedures remove the precancerous areas in about 80 percent of women.
Less troublesome low-grade lesions usually are just monitored. They pose less of a cancer risk and usually regress on their own.
Clears Out The Virus
If a vaccine is eventually approved for use, the slow development of cervical cancer would leave an opening for patients to try it.
“It typically takes about 10 or more years for precancerous cells to become cancer, so there is a window of opportunity to intervene with nonsurgical approaches,” Trimble says.
The new study involved a vaccine developed by University of Pennsylvania scientist David Weiner that is engineered to teach immune system cells to recognize precancerous and cancerous cells.
Between 2011 and 2013, the scientists recruited 167 women, 18 to 55, with newly diagnosed, high-grade precancerous cervical lesions. The women were randomly assigned to receive either three doses of the vaccine over a 12-week period or saline injections.
48.2% Regression Rate
Of 114 who received at least one vaccine dose, 55 (48.2 percent) had regression of their precancerous lesions, meaning they disappeared or converted to low-grade lesions, compared with 12 of 40 (30 percent) who received saline. The regression rate was closer to 50 percent in 107 women who received all three vaccine doses.
“In many of these women, the vaccine not only made their lesions disappear, but it also cleared the virus from their cervix,” Trimble says. “In most unvaccinated patients whose lesions went away, the virus was still present, and many still had low-grade lesions.”
Clearance of the virus is a “significant bonus,” she says, because lingering HPV is a major risk factor for recurrence of cervical lesions.
In biopsy samples, patients whose lesions completely regressed after vaccination had more immune T cells in the tissue.
“It’s important that T cells capable of recognizing HPV stay in the cervix and fight off any recurrence of the infection,” Trimble says.
She is also studying other types of vaccines to prevent high-grade cervical lesions from developing into cancer.
Trimble, Cornelia L et al. Safety, efficacy, and immunogenicity of VGX-3100, a therapeutic synthetic DNA vaccine targeting human papillomavirus 16 and 18 E6 and E7 proteins for cervical intraepithelial neoplasia 2/3: a randomised, double-blind, placebo-controlled phase 2b trial The Lancet DOI: http://dx.doi.org/10.1016/S0140-6736(15)00239-1
Image: Wellcome Images