The final analysis of the largest efficacy trial of a cervical cancer vaccine was published July 25, 2009, in The Lancet. The study, involving 18,644 women, confirmed GlaxoSmithKline’s Cervarix is highly effective at protecting against the two most common cervical cancer–causing human papillomavirus (HPV) types, 16 and 18. The study also showed that the vaccine provides cross-protection against HPV types 31, 33, and 45, the three most common cancer-causing virus types beyond 16 and 18.
Thomas Breuer, head of global clinical R&D and chief medical officer of GSK Biologicals commented, “These excellent study results confirm the efficacy offered by Cervarix against HPV 16 and 18. For the first time, the results show that this vaccine was effective against cervical precancers associated with the five most common cancer-causing virus types. This is really good news for primary prevention of cervical cancer as it indicates the vaccine could offer women additional protection against cervical cancer beyond what had at first been anticipated.”
The study showed that in women who complied with the trial protocol procedures (87% of the total sample), the vaccine provided 92.9% protection against cervical precancers (cervical intraepithelial neoplasia [CIN] 2+) associated with HPV 16 or 18. A further analysis of the same cohort that excluded lesions not likely to be caused by HPV 16 and 18 revealed that the vaccine was 98.1% effective against cervical precancers (CIN 2+) caused by these two types.
The study showed—for the first time for any cervical cancer vaccine—that Cervarix provided significant cross-protection against precancerous lesions not containing HPV types 16 and/or 18. This additional efficacy could translate into approximately 11% to 16% extra protection against cervical cancer over and above the protection afforded by efficacy against HPV 16 and 18 alone. This effect was mainly driven by protection against HPV types 31, 33 and 45.
Prof. Jorma Paavonen, from the University of Helsinki, Finland, principal investigator on the study and lead author of the publication, commented, “The results show Cervarix is highly effective against the most common cervical cancer-causing virus types and has the potential to substantially reduce the incidence of cervical precancers, cervical cancer, and the associated diagnostic and surgical procedures. The results reaffirm confidence in vaccination as a primary preventative measure against cervical cancer when used alongside screening.”