The U.S. Food and Drug Administration has acknowledged that GlaxoSmithKline's Cervarix successfully blocks the two most cancerous strains of the HPV virus.
The main study of the vaccine enrolled more than 18,000 women who either received Cervarix or a sham treatment. The FDA said the vaccine appears to fight HPV for more than six years, based on company data. Side-effects were minor, such as pain and swelling at the injection site.
Earlier studies of Cervarix showed a higher number of muscular and neurological problems among patients who used the vaccine compared with the alternate treatment.
The FDA said Friday it asked outside experts to examine more recent data from the company to see if Cervarix could have caused those problems.
"The conclusion in the case of each of these efforts was that the data are not sufficient to establish a link," the agency said in its review.
The agency will ask a panel of vaccine experts next week whether Cervarix should be approved for girls and women ages 10 to 25. The FDA is not required to follow the group's advice, though it usually does.
GSK's Cervarix® is a prophylactic vaccine against human papilloma virus (HPV) types 16 and 18. It is being developed for the prevention of precancerous cervical lesions (high-grade cervical intraepithelial neoplasia: CIN grades 2 and 3) and cervical cancer associated with HPV types 16 and 18.
Already licensed in Europe for use in females aged 10-25 years, Cervarix is formulated with the proprietary adjuvant system AS04, which both enhances the immune response and increases the duration of protection against cancer-causing virus types.
In studies, the ASO4 formulation of Cervarix induced higher antibody levels and a more sustained immunological response when compared with a conventionally formulated vaccine with aluminium hydroxide adjuvant alone.
Cervarix already is approved in nearly 100 other countries, but has been delayed in the U.S. since 2007 when the FDA said it needed additional data. It is not approved in Canada.
A positive review from the FDA will clear the British drug company's vaccine to compete in the U.S., though it could face an uphill battle against Merck's vaccine Gardasil, which has been on the market in the U.S. and Canada since 2006.
HPV is a common sexually transmitted disease that has been implicated in the development of precancerous cervical lesions and cervical cancer.
Around 100 types of HPV have been identified to date, of which types 16 and 18 are believed to be responsible for more than 70% of cervical cancers that occur in Europe. Most of the remaining 30% of cases of cervical cancer are thought to be associated with other high-risk types of HPV.
Vaccines developed against HPV types 16 and 18 are designed to prevent the acquisition of HPV infection in at-risk females, therefore providing protection against the development of precancerous cervical lesions that may arise from persistent HPV infection and subsequently lead to cervical cancer.
Since many sexually active women contract HPV infection during their lifetime, prophylactic vaccination needs to be given before females become sexually active.
Current immunisation schemes are targeted at children and adolescents who have not yet been exposed to the HPV virus through sexual activity.
However, Gardasil remains to be the only cervical cancer vaccine that protects against four types of HPV, whereas Cervarix protects against two types.
After breast cancer, cervical cancer is the second leading cause of death in women in the US, in the 20-39 years age group. Estimates indicate that over 280,000 women worldwide die from cervical cancer each year.