No abstract

Women remain at risk of human papillomavirus (HPV) infection for most of their lives. The duration of protection against HPV‐16/18 from prophylactic vaccination remains unknown. We investigated the 10‐year immune response and long‐term safety profile of the HPV‐16/18 AS04‐adjuvanted vaccine (AS04‐HPV‐16/18 vaccine) in females aged between 15 and 55 years at first vaccination. Females who received primary vaccination with three doses of AS04‐HPV‐16/18 vaccine in the primary phase‐III study (NCT00196937) were invited to attend annual evaluations for long‐term immunogenicity and safety. Anti‐HPV‐16/18 antibodies in serum and cervico‐vaginal secretions (CVS) were measured using enzyme‐linked immunosorbent assay (ELISA). Serious adverse events (SAEs) were recorded throughout the follow‐up period. Seropositivity rates for anti‐HPV‐16 remained high (≥96.3%) in all age groups 10 years after first vaccination. It was found that 99.2% of 15–25‐year olds remained seropositive for anti‐HPV‐18 compared to 93.7% and 83.8% of 26–45‐year olds and 45–55‐year olds, respectively. Geometric mean titers (GMT) remained above natural infection levels in all age groups. Anti‐HPV‐16 and anti‐HPV‐18 titers were at least 5.3‐fold and 3.1‐fold higher than titers observed after natural infection, respectively, and were predicted to persist above natural infection levels for ≥30 years in all age groups. At Year 10, anti‐HPV‐16/18 antibody titers in subjects aged 15–25 years remained above plateau levels observed in previous studies. Correlation coefficients for antibody titers in serum and CVS were 0.64 (anti‐HPV‐16) and 0.38 (anti‐HPV‐18). This study concluded that vaccinated females aged 15–55 years elicited sustained immunogenicity with an acceptable safety profile up to 10 years after primary vaccination, suggesting long‐term protection against HPV.

The HPV-16/18 AS04-adjuvanted vaccine (Cervarix®, GlaxoSmithKline Biologicals) has been shown to induce a robust immune response in women aged 15-55 years (103514/NCT00196937). This follow-up study is the first report of persistence of immune response and safety profile through 48 months after vaccination in women aged 15-55 years. In this open-label, age-stratified Phase III study in Germany and Poland (105882/NCT00196937), healthy women aged 15-55 years received 3 doses of HPV-16/18 AS04-adjuvanted vaccine at 0, 1, and 6 months. Anti-HPV-16/18 seropositivity rates and geometric mean antibody titers (GMTs) were assessed by enzyme-linked immunosorbent assay (ELISA) in women aged 15-25 (n=168), 26-45 (n=186) and 46-55 years (n=177) from the time of first vaccination through 48 months. At Month 48, all subjects were seropositive for anti-HPV-16 antibodies and 99.4% were seropositive for anti-HPV-18. Antibody kinetics were as previously reported, with peak response at Month 7 followed by a gradual decline tending towards a plateau in all age groups. Anti-HPV-16/18 GMTs were sustained at Month 48 in all age groups, including women aged 46-55 years in whom GMTs were respectively 11-fold and 5-fold higher than natural infection levels. The vaccine exhibited a clinically acceptable safety profile in all age groups. In summary, the HPV-16/18 AS04-adjuvanted vaccine induces high and sustained immune responses in women aged 15-55 years, with antibody levels remaining several-fold higher than natural infection levels for at least 4 years after the first vaccine dose.

GlaxoSmithKline Biologicals SA.

ObjectiveEvaluation of the long-term HPV-16/18 AS04-adjuvanted vaccine immunogenicity persistence in women.DesignMulticentre, open-label, long-term follow-up (NCT00947115) of a primary phase–III study (NCT00196937).SettingSix centres in Germany and Poland.Population488 healthy women (aged 15–55 years, age-stratified into groups: 15–25, 26–45, and 46–55 years) who received three vaccine doses in the primary study.MethodsImmune responses were evaluated in serum and cervicovaginal secretion (CVS) samples 6 years after dose 1. Anti-HPV-16/18 geometric mean titres (GMTs) were measured by enzyme-linked immunosorbent assay (ELISA), and were used to fit the modified power-law and piecewise models, predicting long-term immunogenicity. Serious adverse events (SAEs) were recorded.Main outcome measuresAnti-HPV-16/18 seropositivity rates and GMTs 6 years after dose 1.ResultsAt 6 years after dose 1, all women were seropositive for anti-HPV–16 and ≥97% were seropositive for anti-HPV–18 antibodies. GMTs ranged from 277.7 to 1344.6 EU/ml, and from 97.6 to 438.2 EU/ml, for anti-HPV–16 and anti-HPV–18, respectively. In all age groups, GMTs were higher (anti-HPV–16, 9.3–45.1-fold; anti-HPV–18, 4.3–19.4-fold) than levels associated with natural infection (29.8 EU/ml). A strong correlation between serum and CVS anti-HPV-16/18 levels was observed, with correlation coefficients of 0.81–0.96 (anti-HPV–16) and 0.69–0.84 (anti-HPV–18). Exploratory modelling based on the 6–year data predicted vaccine-induced anti-HPV-16/18 levels above natural infection levels for at least 20 years, except for anti-HPV–18 in the older age group (piecewise model). One vaccine-related and two fatal SAEs were reported.ConclusionsAt 6 years after vaccination, immune responses induced by the HPV-16/18 AS04-adjuvanted vaccine were sustained in all age groups.