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HPV vaccine offers multisite protection, even among previously exposed women
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PHILADELPHIA — HPV vaccination of women aged 18 to 25 years provides strong combined protection against HPV 16/18 infection at three anatomical sites among those with and without prior HPV exposure, according to study findings presented at the American Association for Cancer Research Annual Meeting.
Previous data from the Costa Rica Vaccine Trial demonstrated strong efficacy against HPV 16/18 at the cervical, anal and oral regions separately, according to study background. However, the combined efficacy of infections at all three anatomic sites had not previously been measured in women with or without prior HPV 16/18 exposure.
Daniel C. Beachler
Daniel C. Beachler, PhD, postdoctoral fellow in the division of cancer epidemiology and genetics at the NCI, and colleagues evaluated data from the Costa Rica Vaccine Trial, a randomized controlled trial of 4,186 women who received the HPV 16/18 vaccine (Cervarix, GlaxoSmithKline) or a control Hepatitis A vaccine.
Researchers collected cervical samples from the women annually, whereas oral and anal samples were collected at a 4-year follow-up visit.
The overall multisite vaccine efficacy — including data from women who had an active cervical HPV 16/18 infection at the time of vaccination (25%) — was 64.8% (95% CI, 54.8-72.8). The multisite efficacy at all three anatomical locations was 83.1% (95% CI, 72.6-89.6) for women without prior HPV exposure and 49.6% (95% CI, 2.7-73.9) among women with prior exposure to HPV.
“We did not test for anal and oral HPV DNA at the time of vaccination, only at the 4-year visit,” Beachler said during a press conference. “We could not get a completely naive population of those individuals with cervical, anal and oral HPV infection, so we don’t have complete information on this study … If we had complete information we would expect that efficacy to be much closer to 100%.”
Vaccine efficacy against HPV 16/18 at more than one anatomic site was 91.4% (95% CI, 81.4-96.6).
Further, HPV 16/18-infected women were significantly less likely to be HPV 16/18 infected at two or more anatomic sites when they received the HPV 16/18 vaccine vs. the control vaccine (7% vs. 30%; P ˂ .01).
“HPV is a local infection that can separately infect the cervical, anal or oral sites where it can occasionally lead to cancer,” Beachler said in a press release. “This study demonstrates that the HPV 16/18 vaccine provides protection at all three sites, particularly among women without evidence of HPV exposure prior to vaccination.
“While the HPV vaccine is not therapeutic and cannot help clear current infections, we did observe that it may help protect some women previously exposed to HPV against subsequent infection at their non-infected sites,” he said.
These results support current U.S. guidelines that recommend routine vaccination for children at age 11 or 12 years and vaccination through age 26 years for those not vaccinated previously, Beachler said. He also added there are three HPV vaccines on the market that protect against HPV at different anatomic sites; however, only half of women in the United States aged younger than 18 years have received a CDC-recommended vaccine.
“There are ongoing follow-ups to see the duration of the protection and they’ve been going on for 10 years now and we are still seeing strong protection,” Beachler said at the press conference. “These studies are still going to be followed … but at this point there is no need for a ‘booster.’” – by Anthony SanFilippo
Reference:
Beachler DC, et al. Abstract 1088. Presented at: American Association for Cancer Research Annual Meeting; April 18-22, 2015; Philadelphia.
Disclosure: GlaxoSmithKline PLC provided the vaccines. Beachler reported no relevant financial disclosures. HemOnc Today was unable to obtain a list of relevant disclosures for the other researchers.
Perspective
Back to TopBarbara A. Burtness, MD
The Costa Rica Vaccine Trial looked at giving HPV 16 and 18 vaccine to about 4,000 women in Costa Rica. There were two really interesting findings from this abstract. First, in addition to collecting cervical samples, the researchers also looked for evidence of oral and anal infection. They were able to show that this vaccine gave about 83% protection from infection that carried across all three sites in individuals who were HPV 16/18 naive. So, given that in the United States we are in a period in which the incidence of HPV-associated tonsil cancer is rising 3% yearly and actually projected to overtake cervical cancer as a public health problem, it is very reassuring and helpful to see that this vaccine is protective at all three sites.The other thing that was very interesting in this abstract was that they had a cohort of women who had evidence of prior HPV 16/18 infection and, nonetheless, being exposed to the vaccine protected them, with about a 53% reduction from oral or anal HPV infections. This only highlights the importance of using this vaccine, the need for catch-up strategies so that unvaccinated people will still be offered vaccine even if there is evidence that they may have been previously exposed, and realizing what an important tool this is in bringing a halt to the tonsil cancer epidemic.
Perspective
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Miriam Lango, MD
The study by Beachler and colleagues examines the efficacy of a vaccine against HPV in preventing infection with the HPV numbers 16 and 18, which are known to cause cancer of the cervix, oropharynx and anus.
In this randomized study, women aged 18 to 25 years were randomly assigned to receive a vaccine either against HPV or alternatively against hepatitis A, a virus that causes food- and water-borne illness. Women were then followed for 4 years and samples were collected and tested for evidence of HPV infection. Samples from the cervix were collected annually, while samples from oral and anal sites were collected only once, 4 years after vaccination.
The authors found that vaccinations protected against HPV infection. Surprisingly, vaccination against HPV not only protected women without prior exposure to HPV, but also women who had evidence of HPV infection prior to vaccination. Currently, it is believed that HPV vaccination does not protect those already exposed to the virus. Vaccinating previously infected individuals may, however, enhance the immune response against HPV, helping to ward off further infections. Nevertheless, vaccinating individuals without prior HPV infection is still far more efficacious.
The authors found that vaccination against HPV was over 90% efficacious in preventing not only cervical but also oral and anal HPV infection, 4 years after vaccination. This is important because HPV is known to cause cancer at different parts of the body. In fact, the incidence of oropharyngeal cancer due to HPV infection is increasing at an unprecedented rate. These data suggest that vaccination will protect individuals from developing cancers at multiple sites, and appears to provide some protection to individuals with exposure to HPV prior to vaccination.
Some questions remain. For example, we still do not know how long the vaccine protects against HPV infection. We also don’t know the level of benefit to males undergoing vaccination. However, it seems likely that vaccination would help prevent oral and anal infection and diminish the risk for cancer in men.
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