Updated results from a large clinical trial of the HPV vaccine Cervarix® (human papillomavirus bivalent [types 16 and 18] recombinant vaccine) confirm its protection against cervical precancer and cancer and also provide evidence of cross-protection against other high-risk types of HPV. These results were published in Lancet Oncology.
Human papillomaviruses (HPV) consist of more than 100 different viruses. Some types of HPV cause warts on the hands or feet; others cause genital warts; and some have been linked with cancer, most notably cervical cancer.
There are currently two FDA-approved vaccines that protect against the types of HPV associated with cervical cancer. These are: Gardasil® (quadrivalent human papillomavirus [types 6, 11, 16, 18] recombinant vaccine), which prevents infection with four types of HPV—types 6, 11, 16, and 18; and Cervarix® (human papillomavirus bivalent [types 16 and 18] recombinant vaccine), which targets HPV types 16 and 18. HPV types 16 and 18 cause roughly 70% of all cases of cervical cancer, and HPV types 6 and 11 account for roughly 90% of genital warts.
PATRICIA (Papilloma Trial against Cancer in Young Adults) is a large study that assessed the safety and efficacy of Cervarix. The study—conducted in 14 countries—enrolled more than 18,000 young women between the ages of 15 and 25. Study participants were given either three doses of Cervarix or three doses of a hepatitis A vaccine. The group that received the hepatitis A vaccine served as the comparison group.
Initial results from the study, published in 2009, indicated that Cervarix substantially reduced the risk of cervical precancer and cancer. The new analysis provides updated results based on four years of follow-up.
- Among women with no evidence of HPV exposure at the start of the study, Cervarix provided complete protection against HPV16- or HPV18-related cervical intraepithelial neoplasia (CIN) 3 or worse.
- Cervarix provided less protection to women who may have had prior exposure to HPV. This highlights the importance of vaccinating girls before they become sexually active.
- In addition to protecting against HPV types 16 and 18, there was also evidence that Cervarix provides cross-protection against four other cancer-related types of HPV: HPV types 33, 31, 45, and 51.
These results confirm the efficacy of Cervarix and also provide evidence of cross-protection against certain other high-risk types of HPV.
HPV vaccines are likely to substantially reduce the burden of HPV-related diseases such as cervical cancer. Because HPV infection is extremely common and generally occurs soon after the onset of sexual activity, vaccination is most effective when given before a young person becomes sexually active.
Wheeler CM, Castellsague X, Garland SM et al. Cross-protective efficacy of HPV-16/18 AS04-adjuvanted vaccine against cervical infection and precancer caused by non-vaccine oncogenic HPV types: end-of-study analysis of the randomised, double-blind PATRICIA trial. Lancet Oncology. Early online publication November 9, 2011.
Lehtinen M, Paavonen J, Wheeler CM et al. Overall efficacy of HPV-16/18 AS04-adjuvanted vaccine against grade 3 or greater cervical intraepithelial neoplasia: 4-year end-of-study analysis of the randomised, double-blind PATRICIA trial. Lancet Oncology. Early online publication November 9, 2011.
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