Vaccines are now available for the prevention of HPV-16/18-related cervical infections and pre-cancers, primarily targeting adolescent girls. Since the risk of HPV exposure potentially persists throughout a woman's sexual life, vaccine-derived immunity should be long-term. The current study, HPV-024 (NCT00546078, http://clinicaltrials.gov), assessed the immune memory in North American women who received three doses of HPV-16/18 AS04-adjuvanted vaccine 7 years earlier in HPV-001 (NCT00689741).
Women vaccinated in HPV-001 received a 4th-dose of the HPV-16/18 vaccine (024-4DV group, N=65). Post 4th-dose immune responses were compared with post 1st-dose immune responses in cross-vaccination controls (024-3DV group, N=50). Reactogenicity was compared between the 4th-dose and the 1st-dose administration.
Pre 4th-dose, 100% of subjects in the 024-4DV group remained seropositive for anti-HPV-16/18 antibodies (ELISA). Compared to pre 4th-dose, GMTs for anti-HPV-16 and anti-HPV-18 antibodies were respectively 9.3-fold and 8.7-fold higher at day 7, and 22.7-fold and 17.2-fold higher at month 1. Compared to post 1st-dose, GMTs for anti-HPV-16 and anti-HPV-18 were respectively 80.5-fold and 205.4-fold higher at day 7, and 11.8-fold and 20.5-fold higher at month 1. Furthermore, 68.2% and 77.3% of women had HPV-16/18 specific memory B-cells, respectively, pre 4th-dose, rising to 100% one month post 4th-dose vaccination. The 4th-dose was generally well tolerated.
A 4th-dose of HPV-16/18 AS04-adjuvanted vaccine triggered a rapid and strong anamnestic response in previously vaccinated women, demonstrating vaccine-induced immune memory.
[Show abstract][Hide abstract] ABSTRACT: Protection against oncogenic non-vaccine types (cross-protection) offered by human papillomavirus (HPV) vaccines may provide a significant medical benefit. Available clinical efficacy data suggest the two licensed vaccines (HPV-16/18 vaccine, GlaxoSmithKline Biologicals (GSK), and HPV-6/11/16/18 vaccine, Merck & Co., Inc.) differ in terms of protection against oncogenic non-vaccine HPV types -31/45. The immune responses induced by the two vaccines against these two non-vaccine HPV types (cross-reactivity) was compared in an observer-blind study up to Month 24 (18 mo post-vaccination), in women HPV DNA-negative and seronegative prior to vaccination for the HPV type analyzed (HPV-010 [NCT00423046]). Geometric mean antibody titers (GMTs) measured by pseudovirion-based neutralization assay (PBNA) and enzyme-linked immunosorbent assay (ELISA) were similar between vaccines for HPV-31/45. Seropositivity rates for HPV-31 were also similar between vaccines; however, there was a trend for higher seropositivity with the HPV-16/18 vaccine (13.0-16.7%) versus the HPV-6/11/16/18 vaccine (0.0-5.0%) for HPV-45 with PBNA, but not ELISA. HPV-31/45 cross-reactive memory B-cell responses were comparable between vaccines. Circulating antigen-specific CD4+ T-cell frequencies were higher for the HPV-16/18 vaccine than the HPV-6/11/16/18 vaccine (HPV-31 [geometric mean ratio [GMR] =2.0; p=0.0002] and HPV-45 [GMR=2.6; p=0.0092]), as were the proportion of T-cell responders (HPV-31, p=0.0009; HPV-45, p=0.0793). In conclusion, immune response to oncogenic non-vaccine HPV types -31/45 was generally similar for both vaccines with the exception of T-cell response which was higher with the HPV-16/18 vaccine. Considering the differences in cross-protective efficacy between the two vaccines, the results might provide insights into the underlying mechanism(s) of protection.
Human vaccines 12/2011; 7(12):1359-73. DOI:10.4161/hv.7.12.18282 · 3.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Human papillomavirus (HPV) vaccination offers potential for primary, prevention of HPV-related pre-cancers and cancers as demonstrated in clinical trials. Mathematical, models have estimated the potential real-life impact of vaccination on the burden of cervical cancer, (CC). However, these are restricted to evaluations in a limited number of countries.
Potential decline in CC cases and deaths with the AS04-adjuvanted HPV-16/18 vaccine of, young girls, naïve to HPV, was estimated at steady-state (vaccine coverage: 0-100%) based on clinical, trial and country-specific incidence data. Data on vaccine efficacy were taken from the end of study, PATRICIA trial of the AS04-adjuvanted HPV-16/18 vaccine. The numbers of cases and deaths due to, HPV-16/18 were estimated and compared with those due to any HPV type to estimate the additional, cases prevented. This difference estimates CC cases and deaths avoided due to protection against non-vaccine, HPV types. Cost-offsets due to reductions in CC treatment were estimated for five countries, (Brazil, Canada, Italy, Malaysia and South African Republic) using country-specific unit cost data. Additionally, cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3)-related burden (cases, treatment and costs) prevented by vaccination were estimated for two countries (Italy and Malaysia).
HPV vaccination could prevent a substantial number of CC cases and deaths in countries, worldwide, with associated cost-offsets due to reduced CC treatment. Cross-protection increased the estimated potential number of CC cases and deaths prevented by 34 and 18% in Africa and Oceania, respectively. Moreover, vaccination could result in a substantial reduction in the number of CIN2/3, lesions and associated costs.
HPV vaccination could reduce the burden of CC and precancerous lesions in countries, worldwide, part of disease burden reduction being related to protection against non HPV-16/18, related types.
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