Abstract
In a phase III study, Merck's V503 human papillomavirus (HPV) vaccine prevented 97% of high-grade, precancerous vaginal, vulvar, and cervical disease caused by HPV types 31, 33, 45, 52, and 58. The new vaccine also generated immune responses to HPV types 6, 11, 16, and 18 that were as good as or better than those generated by the company's Gardasil vaccine.
In a phase III study, Merck's new V503 human papillomavirus (HPV) vaccine prevented 97% of high-grade, precancerous vaginal, vulvar, and cervical disease caused by HPV types 31, 33, 45, 52, and 58. The new vaccine also generated immune responses to HPV types 6, 11, 16, and 18 that were as good as or better than those generated by the company's Gardasil vaccine.
“This is great news,” says Patti Gravitt, PhD, professor of pathology at the University of New Mexico in Albuquerque. “If this vaccine can be made affordable to the countries with the highest burden of cervical cancer, such as India, and can be effectively delivered to girls prior to sexual debut, it offers an unprecedented opportunity for reducing the global burden of cervical cancer.”
“The efficacy results are outstanding,” says Jane Kim, PhD, associate professor for health decision science at the Harvard School of Public Health in Boston, MA. “This product has the potential to be a game changer not only in poorer countries, but also in the United States, where it could be an opportunity to diminish the need for repeated Pap screenings.”
The study involved more than 14,000 women ages 16 to 26. Approximately half were vaccinated with V503 and half with Gardasil.
HPV types 6, 11, 16, and 18 cause about 70% of cervical cancers worldwide. The five additional HPV types covered in V503 cause an additional 20%. As a result, V503 has the potential to prevent approximately 90% of cervical cancers.
Because cervical cancers take a long time to develop, the study did not use cancer as an endpoint for the five additional HPV types. It instead looked at high-grade vaginal, vulvar, and cervical disease. “There's enough evidence to support that high-grade disease is an established cancer precursor,” says Kim. “That's what we screen for using the Pap smear.”
Separately in November, another study that may affect HPV vaccination worldwide was published in Cancer Prevention Research. This study found that one dose of GlaxoSmithKline's Cervarix (which guards against HPV types 16 and 18) creates an immune response that remains stable for 4 years, suggesting that one dose of that vaccine might provide long-term protection against cervical cancer. The current standard for Cervarix and Gardasil requires three doses of vaccine.
A one-dose regimen could make vaccination more routine in the developing world, where 85% of cases of cervical cancer occur, because the three-dose regimen is logistically challenging and costly, even with recent price reductions. “To cut that vaccine cost to a third would be amazing,” says Kim, who cautions that more work is required to understand the possible need for and potential timing of booster doses.