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Cross-protective efficacy of HPV-16/18 AS04-adjuvanted vaccine against cervical infection and precancer caused by non-vaccine oncogenic HPV types: 4-year end-of-study analysis of the randomised, double-blind PATRICIA trial.
Persistent infection with high-risk (HR) human papillomavirus (HPV) is the underlying cause of cervical cancer.1 HR HPV types 16/18 have the highest type-specific risk of cervical cancer development2 and predominate in 70% of cervical cancer cases worldwide.3
There are two licensed prophylactic HPV vaccines: Cervarix™ targeting 16/18 and Gardasil® targeting 16/18 and HPV types 6/11 that cause genital warts. Clinical trials of both vaccines demonstrate high vaccine efficacy for prevention of cervical intraepithelial neoplasia grade 2 or greater (CIN2+).4 5 The clinical evidence supported the UK-wide implementation of Cervarix, for cervical cancer prevention, from September 2008. The vaccination programme began in schools targeting girls aged 12–13 years, with a catch-up campaign for girls aged 14–17 years.
In January 2012, the 4-year end-of-study analysis from the HPV PApilloma TRIal against Cancer In young Adults (PATRICIA) Phase III randomised, double-blind study of Cervarix was published in Lancet Oncology. In women who had not been exposed to the virus, the vaccine had 100% efficacy against HPV16/18-associated CIN3+ and adenocarcinoma, supporting the benefit of vaccination early in adolescence.6 The total vaccinated cohort included women who were sexually active and overall vaccine efficacy against HPV16/18-associated CIN3+ was 45.6%, highlighting how the catch-up vaccination campaign would be beneficial to the UK population.
Wheeler et al.7 reported data on the cross-protective vaccine efficacy of Cervarix against persistent infection and CIN2+/CIN3+ associated with non-vaccine-targeted types. In HPV-naïve women, vaccine efficacy against 12 non-vaccine types associated with CIN3+ excluding HPV16/18 co-infection was 81.9% as a result of cross-protection. This suggests Cervarix may confer additional protection against cervical cancer development.
The overall findings from the PATRICIA study group highlight how the success of the HPV vaccination programme is dependent upon vaccine uptake before exposure to the virus, in conjunction with good programme coverage.8
The most effective method for global cervical cancer prevention would be introduction of the vaccine in low-resource settings, where cervical cancer incidence remains high, due to limited resources for screening, prevention and treatment.
Competing interests None.
Provenance and peer review Commissioned; internally peer reviewed.
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