Proof-of-Principle Evaluation of the Efficacy of Fewer Than Three Doses of a Bivalent HPV16/18 Vaccine

Infections and Immunoepidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Blvd, EPS/7084, Rockville, MD 20852, USA.
CancerSpectrum Knowledge Environment (Impact Factor: 15.16). 09/2011; 103(19):1444-51. DOI: 10.1093/jnci/djr319
Source: PubMed

ABSTRACT Three-dose regimens for human papillomavirus (HPV) vaccines are expensive and difficult to complete, especially in settings where the need for cervical cancer prevention is greatest.
We evaluated the vaccine efficacy of fewer than three doses of the HPV16/18 vaccine Cervarix in our Costa Rica Vaccine Trial. Women were randomly assigned to receive three doses of the HPV16/18 vaccine or to a control vaccine and were followed for incident HPV16 or HPV18 infection that persisted in visits that were 10 or more months apart (median follow-up 4.2 years). After excluding women who had no follow-up or who were HPV16 and HPV18 DNA positive at enrollment, 5967 women received three vaccine doses (2957 HPV vaccine vs 3010 control vaccine), 802 received two doses (422 HPV vs. 380 control), and 384 received one dose (196 HPV vs. 188 control). Reasons for receiving fewer doses and other pre- and post-randomization characteristics were balanced within each dosage group between women receiving the HPV and control vaccines.
Incident HPV16 or HPV18 infections that persisted for 1 year were unrelated to dosage of the control vaccine. Vaccine efficacy was 80.9% for three doses of the HPV vaccine (95% confidence interval [CI] = 71.1% to 87.7%; 25 and 133 events in the HPV and control arms, respectively), 84.1% for two doses (95% CI = 50.2% to 96.3%; 3 and 17 events), and 100% for one dose (95% CI = 66.5% to 100%; 0 and 10 events).
Four years after vaccination of women who appeared to be uninfected, this nonrandomized analysis suggests that two doses of the HPV16/18 vaccine, and maybe even one dose, are as protective as three doses.

  • [Show abstract] [Hide abstract]
    ABSTRACT: It has been more than 7 years since the commercial introduction of highly successful vaccines protecting against high-risk human papillomavirus (HPV) subtypes and the development of cervical cancer. From an immune standpoint, the dependence of cervical cancer on viral infection has meant that HPV proteins can be targeted as strong tumour antigens leading to clearance of the infection and the subsequent protection from cancer. Commercially available vaccines consisting of the L1 capsid protein assembled as virus-like particles (VLPs) induce neutralising antibodies that deny access of the virus to cervical epithelial cells. While greater than 90% efficacy has been demonstrated at the completion of large phase III trials in young women, vaccine developers are now addressing broader issues such as efficacy in boys, longevity of the protection and inducing cross-reactive antibody for oncogenic, non-vaccine HPV strains. For women with existing HPV infection, the prophylactic vaccines provide little protection, and consequently, the need for therapeutic vaccines will continue into the future. Therapeutic vaccines targeting HPVE6 and E7 proteins are actively being pursued with new adjuvants and delivery vectors, combined with an improved knowledge of the tumour microenvironment, showing great promise. This review will focus on recent progress in prophylactic and therapeutic vaccine development and implementation since the publication of end of study data from phase III clinical trials between 2010 and 2012. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
    Reviews in Medical Virology 03/2015; 25:54-71. DOI:10.1002/rmv.1824 · 5.76 Impact Factor
  • JNCI Journal of the National Cancer Institute 03/2015; 107(3). DOI:10.1093/jnci/dju436 · 15.16 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we review the published evidence about the long-term efficacy of the available human papillomavirus (HPV) vaccines and their safety profile. Two prophylactic HPV vaccines - bivalent (bHPV) and quadrivalent (qHPV) - are now available, and vaccination programs are being widely implemented, primarily targeting adolescent girls. Efficacy has been widely demonstrated for both vaccines. Since the risk of HPV exposure potentially persists throughout a woman's sexual life, vaccine duration of protection is critical to overall effectiveness. Interpreting the results of long-term efficacy studies for the two HPV vaccines can be puzzling, due to the heterogeneity of studies, different methods used in the assessment of immunogenicity, histopathological and virological end points, and statistical power issues. Moreover, an immunologic correlate of protection has not yet been established, and it is unknown whether higher antibody levels will really result in a longer duration of protection. Disease prevention remains the most important measure of long-term duration of vaccine efficacy. To date, the longest follow-up of an HPV vaccine has been 9.4 years for the bHPV vaccine. Long-term follow-up for qHPV vaccine goes up to 8 years. The vaccine continues to be immunogenic and well tolerated up to 9 years following vaccination. All randomized controlled clinical trials of the bHPV and the qHPV vaccines provide evidence of an excellent safety profile. The most common complaint reported is pain in the injection site, which is self-limiting and spontaneously resolved. The incidence of systemic adverse events (AEs), serious AEs, and discontinuations due to a serious AE reported in clinical studies are similar between the two vaccines and their control groups. In particular, no increased risk of autoimmune disease has been shown among HPV-vaccinated subjects in long-term observation studies. As these are crucial topics in HPV vaccination, it is important to establish systems for continued monitoring of vaccine immunogenicity, efficacy, and safety over time.
    International Journal of Women's Health 01/2014; 6:999-1010. DOI:10.2147/IJWH.S50365

Full-text (2 Sources)

Available from
May 23, 2014