A vaccine that blocks infection by four types of viruses could cut global deaths from cervical cancer by more than two thirds, its manufacturer says.
Merck & Co wants America’s Food and Drug Administration to approve its Gardasil vaccine against the two of those four types of human papillomavirus, or HPV, believed to be responsible for about 70% of cervical cancer cases.
HPV is the most common sexually-transmitted disease, affecting more than 50% of sexually active adults. The cervical cancer it can cause kills about 290,000 women worldwide each year. The other two types the vaccine protects against cause 90% of genital wart cases.
Today a panel of FDA advisers will begin discussing whether to recommend FDA approval for the vaccine against HPV. The FDA is not required to follow the advice of its expert panels, but usually does. An agency decision is expected by June 8.
FDA reviewers said Gardasil appeared safe and effective, but warned that it may lead to an increased number of cases of a cancer precursor among patients already infected by any of the four virus types at the time they received the vaccine, and whose immune systems had not cleared the virus from their bodies.
Furthermore, any advantage the vaccine provides in protecting against the four virus types could be offset by infection by any of the multiple other types of HPV that the vaccine does not cover, according to FDA briefing documents released before the meeting.
FDA staff also asked that the committee examine five cases where children with birth defects were born to women who had received the vaccine around the time of conception.
According to the documents, the FDA’s Vaccines and Related Biological Products advisory committee should discuss those items only if its members first agree that studies show the vaccine is safe and effective. That suggests the FDA favours its approval.
New Jersey-based Merck developed the vaccine and tested it in both women and men, but today’s discussion is expected to focus on its use in preventing HPV-related disease in women.
Pending FDA action, the national Advisory Committee on Immunisation Practices will decide later in June whether to endorse routine vaccination with Gardasil. The committee’s HPV vaccine workgroup is recommending the vaccine be given to girls of 11 and 12 and the committee will consider recommendations for females aged 13 to 26.
Widespread vaccination with the vaccine could help bounce cervical cancer from its dubious distinction as the second most common cancer in women worldwide. However, the anticipated cost of the vaccine, administered in three shots over six months, is £165 to £275 and could pose a barrier to that goal.
Early opposition to Gardasil, based on concerns it could encourage sexual activity in the young, largely dissipated, in part because of the vaccine’s cancer-reduction implications.