| Pharmaco-therapeutic group: Papillomavirus vaccines, ATC code: J07BM02 Mechanism of action Cervarix is a non-infectious recombinant vaccine prepared from the highly purified virus-like particles (VLPs) of the major capsid L1 protein of oncogenic HPV types 16 and 18. Since the VLPs contain no viral DNA, they cannot infect cells, reproduce or cause disease. Animal studies have shown that the efficacy of L1 VLP vaccines is largely mediated by the development of a humoral immune response.HPV-16 and HPV-18 are responsible for approximately 70% of cervical cancers across all regions worldwide.Clinical studies The efficacy of Cervarix was assessed in two controlled, double-blind, randomised Phase II and III clinical trials that included a total of 19,778 women aged 15 to 25 years.The phase II trial (study 001/007) enrolled only women who:- Were tested negative for oncogenic HPV DNA of types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68- Were seronegative for HPV-16 and HPV-18 and - Had normal cytologyThe primary efficacy endpoint was incident infection with HPV-16 and/or HPV-18. Twelve-month persistent infection was evaluated as additional efficacy endpoint.The phase III trial (study 008) enrolled women without pre-screening for the presence of HPV infection, i.e. regardless of baseline cytology and HPV serological and DNA status.The primary efficacy endpoint was CIN2+ associated with HPV-16 and/or HPV-18. The secondary endpoints included 12-month persistent infection.Cervical Intraepithelial Neoplasia (CIN) grade 2 and 3 was used in the clinical trials as a surrogate marker for cervical cancer.The term premalignant cervical lesions in section 4.1 corresponds to high-grade Cervical Intraepithelial Neoplasia (CIN 2/3).Prophylactic efficacy against HPV-16/18 infection in a population naïve to oncogenic HPV types Women (N=1,113) were vaccinated in study 001 and evaluated for efficacy up to month 27. A subset of women (N=776) vaccinated in study 001 was followed in study 007 up to 6.4 years (approximately 77 months) after the first dose (mean follow-up of 5.9 years). There were five cases of 12-month persistent HPV-16/18 infection (4 HPV-16; 1 HPV-18) in the control group and one HPV-16 case in the vaccine group in study 001. In study 007 the efficacy of Cervarix against 12-month persistent HPV-16/18 infection was 100% (95% CI: 80.5; 100). There were sixteen cases of persistent HPV-16 infection, and five cases of persistent HPV-18 infection, all in the control group.Prophylactic efficacy in women naïve to HPV-16 and/or HPV-18 In study 008 the primary analyses of efficacy were conducted in the total vaccinated cohort (TVC-1). This cohort included only women who were HPV DNA negative and seronegative to the relevant HPV type (HPV-16 or HPV-18) at study entry and had received at least one dose of Cervarix or the control. Women with high-grade or missing cytology (0.5%) were excluded from the efficacy analysis.Overall, 74.0% of women enrolled were naïve to both HPV-16 and HPV-18 at study entry.The efficacy of Cervarix in the prevention of CIN2+ associated with HPV-16 and/or HPV-18 as assessed up to 15 months after the last dose of vaccine or control and the rates of 12-month persistent infection in the TVC-1 cohort are presented in the table below:Study 008 | Cervarix | Control | Efficacy (97.9% CI) | N | n | N | n | CIN2+ (primary endpoint) | HPV-16 and/or 18* | 7788 | 2 | 7838 | 21 | 90.4 (53.4; 99.3) | HPV-16 | 6701 | 1 | 6717 | 15 | 93.3 (47.0; 99.9) | HPV-18 | 7221 | 1 | 7258 | 6 | 83.3 (<0.0; 99.9) | 12-month persistent infection (secondary endpoint) | HPV-16 and/or 18* | 3386 | 11 | 3437 | 46 | 75.9 (47.7; 90.2) | HPV-16 | 2945 | 7 | 2972 | 35 | 79.9 (48.3; 93.8) | HPV-18 | 3143 | 4 | 3190 | 12 | 66.2 (<0.0; 94.0) | N = number of subjects included in each group of TVC-1 cohort n = number of cases *protocol-specified endpoints | All endpoints reached statistical significance for HPV-16. For HPV-18, the difference between the vaccine and control groups was not statistically significant for CIN2+ and 12 month persistent infection (TVC-1 cohort). However, in a pre-specified analysis (TVC-2) that was identical to the TVC-1 analysis except that it excluded women with abnormal cytology at study entry, the 12 month persistent infection endpoint for HPV-18 reached statistical significance with vaccine efficacy of 89.9% (97.9% CI: 11.3; 99.9). One case was observed in the vaccine group versus 10 cases in the control group.Several of the CIN2+ lesions contained multiple oncogenic types (including non-vaccine HPV types). An additional analysis was conducted to determine vaccine efficacy against lesions likely to be causally associated with HPV-16 and/or HPV-18. This post-hoc analysis (clinical case assignment) assigned causal association of an HPV type with the lesion based on the presence of the HPV type in cytology samples prior to detection of the lesion. Based on this case assignment, the analysis excluded 3 CIN2+ cases (2 in the vaccine group and 1 in the control group) which were not considered to be causally associated with HPV-16 or HPV-18 infections acquired during the trial. Based on this analysis there were no cases in the vaccine group and 20 cases in the control group (Efficacy 100%; 97.9% CI: 74.2; 100).Prophylactic efficacy in women with current or prior infection There was no evidence of protection from disease caused by the HPV types for which subjects were HPV DNA positive at study entry. However, individuals already infected with one of the vaccine-related HPV types prior to vaccination were protected from clinical disease caused by the remaining HPV type.In study 008, approximately 26% of women had evidence of current and/or prior infection. Twenty percent of women had evidence of prior infection (i.e. HPV-16 and/or HPV-18 seropositive). Seven percent of women were infected at time of vaccination (i.e. HPV-16 and/or HPV-18 DNA positive) of which only 0.5% were DNA positive for both types.Immunogenicity No minimal antibody level associated with protection against CIN of grade 2 or 3 or against persistent infection associated with vaccine HPV types has been identified for HPV vaccines.The antibody response to HPV-16 and HPV-18 was measured using a type-specific ELISA which was shown to correlate with the pseudovirion-based neutralisation assay. The immunogenicity induced by three doses of Cervarix has been evaluated in 5,303 female subjects from 10 to 55 years of age.In clinical trials, 99.9% of initially seronegative subjects had seroconverted to both HPV types 16 and 18 one month after the third dose. Vaccine-induced IgG Geometric Mean Titres (GMT) were well above titres observed in women previously infected but who cleared HPV infection (natural infection). Initially seropositive and seronegative subjects reached similar titres after vaccination.Study 001/007, which included women from 15 to 25 years of age at the time of vaccination, evaluated the immune response against HPV-16 and HPV-18 up to 76 months post dose 1.Vaccine-induced IgG Geometric Mean Titres (GMT) for both HPV-16 and HPV-18 peaked at month 7 and then declined to reach a plateau from month 18 up to the end of the follow-up (month 76). At the end of the follow-up period, GMTs for both HPV-16 and HPV-18 were still at least 11-fold higher than titres observed in women previously infected but who cleared HPV infection and >98% of the women were still seropositive for both antigens. In study 008, immunogenicity at month 7 was similar to the response observed in study 001.In another clinical trial (study 014) performed in women aged 15 to 55 years, all subjects seroconverted to both HPV types 16 and 18 after the third dose (at month 7). The GMTs were, however, lower in women above 25 years. Nevertheless, all subjects remained seropositive for both types throughout the follow-up phase (up to month 18) maintaining antibody levels at an order of magnitude above those encountered after natural infection.Bridging the efficacy of Cervarix from young adult women to adolescents In two clinical trials performed in girls and adolescents aged 10 to 14 years, all subjects seroconverted to both HPV types 16 and 18 after the third dose (at month 7) with GMTs at least 2-fold higher as compared to women aged 15 to 25 years. On the basis of these immunogenicity data, the efficacy of Cervarix is inferred from 10 to 14 years of age. | |