Sustained Immunogenicity of 2-dose Human Papillomavirus 16/18 AS04-adjuvanted Vaccine Schedules in Girls Aged 9-14 Years: A Randomized Trial

Different dose series of human papillomavirus vaccine in young females: a pair-wise meta-analysis and network meta-analysis from randomized controlled trials

Objective

To investigate the application value of different dose of HPV vaccine in young females.

Data sources

The following databases were searched: Cochrane Library, PubMed, Embase, Web of Science, SINOMED, and Wanfang Data, from the establishment of the database to August 1st, 2022.

Study eligibility criteria

The inclusion criterias were: healthy young women younger than 25 years old as the research object, randomized controlled study as the research type, and the efficacy and safety of single-dose, two-dose or three-dose HPV vaccines as the intervention measures and research endpoints.

Study appraisal and synthesis methods

Meta-analysis was performed to analyze the protective effects of single-dose, 2-dose and 3-dose HPV vaccine series on young females.

Results

A total of eight eligible studies involving 16 publications were included. There is no difference in the immunogenicity between the 2-dose and 3-dose series within 12 months after the last dose of HPV vaccine. However, 3-dose series was better than the 2-dose series, which performed better than the single-dose vaccine, after 12 months. With respect to the prevention of HPV16/18 infection or HPV31/33/45 infection, the single-dose vaccine worked better than 2-dose or 3-dose series.

Conclusions

The present study showed that the immunogenicity of low-dose HPV vaccine was significantly less, but it reduced the risk of high-risk HPV infection. The low-dose HPV vaccine series may not offer a preventive effect on cervical lesions, though it needs to be further confirmed by additional studies.

Efficacy, immunogenicity and safety of HPV vaccination in Chinese population: A meta-analysis

Objective

To evaluate the efficacy, immunogenicity and safety of HPV vaccination in Chinese population.

Methods

PubMed, Embase, Web of Science and Cochrane Library from inception to November 2022 were searched to collect information on clinical trials of HPV vaccines. Database search strategy used a combination of subject terms and free terms. Studies were first identified by two authors through reading the title, abstract and full texts and, subsequently, based on the inclusion criteria: Chinese population, with at least one of the following outcomes (efficacy, immunogenicity, and safety), and HPV vaccine RCT, those eligible were included in this paper. Efficacy, immunogenicity and safety data, pooled by random effects models, are presented as risk ratios [95% confidence intervals (CI)].

Results

Eleven RCTs and four follow-up studies were included. Meta-analysis showed that HPV vaccine had good profile of efficacy and immunogenicity. The seroconversion rates were significantly higher among the vaccinated, uninfected (initial negative serum antibody) population than the placebo population for both HPV-16 (RR 29.10; 95% CI: 8.40-100.82) and HPV-18 (RR 24.15; 95% CI: 3.82-152.84), respectively. A significant reduction of the incidence of cervical intraepithelial neoplasia grade 1 (CIN1+) (RR 0.05; 95% CI: 0.01-0.23) and CIN2+ (RR 0.09; 95% CI: 0.02-0.40) was also measured. Risk for serious adverse events after HPV vaccination indicated comparable outcomes between vaccination and placebo.

Conclusions

For Chinese populations, HPV vaccines enhance the level of HPV16- and HPV18-specific antibodies and reduce the incidence of CIN1+ and CIN2+ in uninfected population. Also, the risk of serious adverse events in both groups are almost equivalent. More data are needed to establish vaccine efficacy with cervical cancer.

A community intervention effectiveness study of single dose or two doses of bivalent HPV vaccine (CERVARIX®) in female school students in Thailand

Human papillomavirus (HPV) is a common infection principally spread through sexual activity. Most HPV infections are asymptomatic and resolve spontaneously. However, persistent infection may progress to cervical cancer. Highly efficacious HPV vaccines have been available since 2006, yet uptake into national programs has been slow in part due to cost. WHO guidelines call for a two-dose (0,6 month) schedule for girls 9–14 years of age. Post-hoc analyses of randomized trials have found high vaccine effectiveness following a single dose of vaccine. In order to provide additional data on the potential impact of single dose HPV vaccination in a real-world setting, we are conducting an effectiveness study among Thai schoolgirls. This is an observational study of a single dose (SD) or two doses (2D) of the bivalent HPV vaccine CERVARIX® (GlaxoSmithKline plc.) administered in a school-based program to 8–9,000 Grade 8 female students in two provinces of Thailand beginning in 2018; one province is assigned the SD, and the other the standard 2D regimen. The reduction in HPV vaccine-type prevalence will be assessed in each province two and four years after vaccination by comparing HPV prevalence in urine samples obtained through cross-sectional surveys of the immunized grade cohort as they age and compared to a historical “baseline” HPV prevalence of same age students.

A Combined Adjuvant TF-Al Consisting of TFPR1 and Aluminum Hydroxide Augments Strong Humoral and Cellular Immune Responses in Both C57BL/6 and BALB/c Mice

TFPR1 is a novel adjuvant for protein and peptide antigens, which has been demonstrated in BALB/c mice in our previous studies; however, its adjuvanticity in mice with different genetic backgrounds remains unknown, and its adjuvanticity needs to be improved to fit the requirements for various vaccines. In this study, we first compared the adjuvanticity of TFPR1 in two commonly used inbred mouse strains, BALB/c and C57BL/6 mice, in vitro and in vivo, and demonstrated that TFPR1 activated TLR2 to exert its immune activity in vivo. Next, to prove the feasibility of TFPR1 acting as a major component of combined adjuvants, we prepared a combined adjuvant, TF-Al, by formulating TFPR1 and alum at a certain ratio and compared its adjuvanticity with that of TFPR1 and alum alone using OVA and recombinant HBsAg as model antigens in both BALB/c and C57BL/6 mice. Results showed that TFPR1 acts as an effective vaccine adjuvant in both BALB/c mice and C57BL/6 mice, and further demonstrated the role of TLR2 in the adjuvanticity of TFPR1 in vivo. In addition, we obtained a novel combined adjuvant, TF-Al, based on TFPR1, which can augment antibody and cellular immune responses in mice with different genetic backgrounds, suggesting its promise for vaccine development in the future.

Three-Year Follow-up of 2-Dose Versus 3-Dose HPV Vaccine

BACKGROUND AND OBJECTIVES

Human papillomavirus (HPV) antibody responses to the 9-valent human papillomavirus (9vHPV) vaccine among girls and boys (aged 9-14 years) receiving 2-dose regimens (months 0, 6 or 0, 12) were noninferior to a 3-dose regimen (months 0, 2, 6) in young women (aged 16-26 years) 4 weeks after last vaccination in an international, randomized, open-label trial (NCT01984697). We assessed response durability through month 36.

METHODS

Girls received 2 (months 0 and 6 [0, 6]: n = 301; months 0 and 12 [0, 12]: n = 151) or 3 doses (months 0,2, and 6 [0, 2, 6]: n = 301); boys received 2 doses ([0, 6]: n = 301; [0, 12]: n = 150); and young women received 3 doses ([0, 2, 6]: n = 314) of 9vHPV vaccine. Anti-HPV geometric mean titers (GMTs) were assessed by competitive Luminex immunoassay (cLIA) and immunoglobulin G-Luminex immunoassay (IgG-LIA) through month 36.

RESULTS

Anti-HPV GMTs were highest 1 month after the last 9vHPV vaccine regimen dose, decreased sharply during the subsequent 12 months, and then decreased more slowly. GMTs 2 to 2.5 years after the last regimen dose in girls and boys given 2 doses were generally similar to or greater than GMTs in young women given 3 doses. Across HPV types, most boys and girls who received 2 doses (cLIA: 81%-100%; IgG-LIA: 91%-100%) and young women who received 3 doses (cLIA: 78%-98%; IgG-LIA: 91%-100%) remained seropositive 2 to 2.5 years after the last regimen dose.

CONCLUSIONS

Antibody responses persisted through 2 to 2.5 years after the last dose of a 2-dose 9vHPV vaccine regimen in girls and boys. In girls and boys, antibody responses generated by 2 doses administered 6 to 12 months apart may be sufficient to induce high-level protective efficacy through at least 2 years after the second dose.

Long‐term persistence of immune response to the AS04‐adjuvanted HPV‐16/18 vaccine in Chinese girls aged 9‐17 years: Results from an 8‐9‐year follow‐up phase III open‐label study

Aim

In 9‐17‐year‐old Chinese girls, the AS04‐adjuvanted HPV‐16/18 vaccine (AS04‐HPV‐16/18) given as three‐dose schedule induced high antibody levels, which were noninferior 1 month after the third dose to those observed in 18‐25‐year‐old Chinese women in a large efficacy study. We assessed the persistence of antibodies 8‐9 years after vaccination in the same subjects.

Methods

This follow‐up phase III, open‐label study (NCT03355820) included subjects who had received three doses of AS04‐HPV‐16/18 in the initial trial (NCT00996125). Serum antibody concentrations were assessed by ELISA and compared to antibody persistence observed in 18‐25‐year‐old Chinese women 6 years after first vaccination in the efficacy study (NCT00779766).

Results

Out of the 227 enrolled subjects, 223 were included in the per‐protocol immunogenicity analysis. Mean interval from first AS04‐HPV‐16/18 dose to blood sampling was 101.4 months (8.5 years). For antibodies against HPV‐16 and ‐18, 8.5 years after first vaccine dose all subjects remained seropositive and antibody. Geometric mean concentrations (GMCs) were 1236.3 (95% confidence interval [CI]: 1121.8; 1362.4) and 535.6 (95% CI: 478.6; 599.4) ELISA Units/mL, respectively. These seropositivity rates and antibody GMCs were higher than those observed 6 years after first vaccination of 18‐25‐year‐old women.

Conclusion

Sustained anti‐HPV‐16 and ‐18 immune responses were observed 8‐9 years after AS04‐HPV‐16/18 vaccination of 9‐17 year‐old Chinese girls that were higher than the ones observed 6 years after first vaccination in Chinese adult women in whom AS04‐HPV‐16/18 efficacy against cervical intraepithelial neoplasia of grade ≥2 was demonstrated.

Immunogenicity of Alternative Dosing Schedules for HPV Vaccines among Adolescent Girls and Young Women: A Systematic Review and Meta-Analysis

Alternative dosing schedules for licensed human papilloma virus (HPV) vaccines, particularly single dose and extended intervals between doses (>12 months), are being considered to address vaccine shortages and improve operational flexibility. We searched PUBMED/MEDLINE for publications reporting immunogenicity data following administration of one of the licensed HPV vaccines (2vHPV, 4vHPV, and 9vHPV) to females aged 9–26 years. We conducted non-inferiority analyses comparing alternative to standard schedules using mixed effects meta-regression controlling for baseline HPV status and disaggregated by vaccine, subtype, time point, and age group (9–14 and 15–26 years). Non-inferiority was defined as the lower bound of the 95% confidence interval (CI) for the geometric mean titer (GMT) ratio being greater than 0.5. Our search returned 2464 studies, of which 23 were included in data analyses. When evaluated against standard schedules, although robust immunogenicity was demonstrated across all multi-dose groups, non-inferiority of extended interval dosing was mixed across vaccines, subtypes, and time points. Single dose did not meet the criteria for non-inferiority in any comparisons. Sparse data limited the number of possible comparisons, and further research is warranted.

Long-term Cross-reactivity Against Nonvaccine Human Papillomavirus Types 31 and 45 After 2- or 3-Dose Schedules of the AS04-Adjuvanted Human HPV-16/18 Vaccine

This analysis focused on long-term cross-reactive immunogenicity against nonvaccine human papillomavirus (HPV) types 31 and 45 following 2 doses of AS04-adjuvanted HPV-16/18 vaccine in girls aged 9-14 years or following 3 doses in women aged 15-25 years, for up to 3 years (HPV-070 study) and up to 5 years (HPV-048 study) after the first vaccination. Both schedules elicited antibodies against HPV-31 and HPV-45 up to 5 years after first dose. The antibody concentration was similar in young girls as compared to women. Specific CD4+ T-cell and B-cell responses to HPV-31 and HPV-45 at month 36 were similar across groups. Clinical trials registration: NCT01381575 and NCT00541970.

Comparison of different human papillomavirus (HPV) vaccine types and dose schedules for prevention of HPV-related disease in females and males

BACKGROUND

Uptake of human papillomavirus (HPV) vaccine remains low in many countries, although the bivalent and quadrivalent HPV vaccines given as a three-dose schedule are effective in the prevention of precancerous lesions of the cervix in women. Simpler immunisation schedules, such as those with fewer doses, might reduce barriers to vaccination, as may programmes that include males.

OBJECTIVES

To evaluate the efficacy, immunogenicity, and harms of different dose schedules and different types of HPV vaccines in females and males.

SEARCH METHODS

We conducted electronic searches on 27 September 2018 in Ovid MEDLINE, the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library), and Ovid Embase. We also searched the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov (both 27 September 2018), vaccine manufacturer websites, and checked reference lists from an index of HPV studies and other relevant systematic reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with no language restriction. We considered studies if they enrolled HIV-negative males or females aged 9 to 26 years, or HIV-positive males or females of any age.

DATA COLLECTION AND ANALYSIS

We used methods recommended by Cochrane. We use the term 'control' to refer to comparator products containing an adjuvant or active vaccine and 'placebo' to refer to products that contain no adjuvant or active vaccine. Most primary outcomes in this review were clinical outcomes. However, for comparisons comparing dose schedules, the included RCTs were designed to measure antibody responses (i.e. immunogenicity) as the primary outcome, rather than clinical outcomes, since it is unethical to collect cervical samples from girls under 16 years of age. We analysed immunogenicity outcomes (i.e. geometric mean titres) with ratios of means, clinical outcomes (e.g. cancer and intraepithelial neoplasia) with risk ratios or rate ratios and, for serious adverse events and deaths, we calculated odds ratios. We rated the certainty of evidence with GRADE.

MAIN RESULTS

We included 20 RCTs with 31,940 participants. The length of follow-up in the included studies ranged from seven months to five years. Two doses versus three doses of HPV vaccine in 9- to 15-year-old females Antibody responses after two-dose and three-dose HPV vaccine schedules were similar after up to five years of follow-up (4 RCTs, moderate- to high-certainty evidence). No RCTs collected clinical outcome data. Evidence about serious adverse events in studies comparing dose schedules was of very low-certainty owing to imprecision and indirectness (three doses 35/1159; two doses 36/1158; 4 RCTs). One death was reported in the three-dose group (1/898) and none in the two-dose group (0/899) (low-certainty evidence). Interval between doses of HPV vaccine in 9- to 14-year-old females and males Antibody responses were stronger with a longer interval (6 or 12 months) between the first two doses of HPV vaccine than a shorter interval (2 or 6 months) at up to three years of follow-up (4 RCTs, moderate- to high-certainty evidence). No RCTs collected data about clinical outcomes. Evidence about serious adverse events in studies comparing intervals was of very low-certainty, owing to imprecision and indirectness. No deaths were reported in any of the studies (0/1898, 3 RCTs, low-certainty evidence). HPV vaccination of 10- to 26-year-old males In one RCT there was moderate-certainty evidence that quadrivalent HPV vaccine, compared with control, reduced the incidence of external genital lesions (control 36 per 3081 person-years; quadrivalent 6 per 3173 person-years; rate ratio 0.16, 95% CI 0.07 to 0.38; 6254 person-years) and anogenital warts (control 28 per 2814 person-years; quadrivalent 3 per 2831 person-years; rate ratio 0.11, 95% CI 0.03 to 0.38; 5645 person-years). The quadrivalent vaccine resulted in more injection-site adverse events, such as pain or redness, than control (537 versus 601 per 1000; risk ratio (RR) 1.12, 95% CI 1.06 to 1.18, 3895 participants, high-certainty evidence). There was very low-certainty evidence from two RCTs about serious adverse events with quadrivalent vaccine (control 12/2588; quadrivalent 8/2574), and about deaths (control 11/2591; quadrivalent 3/2582), owing to imprecision and indirectness. Nonavalent versus quadrivalent vaccine in 9- to 26-year-old females and males Three RCTs were included; one in females aged 9- to 15-years (n = 600), one in females aged 16- to 26-years (n = 14,215), and one in males aged 16- to 26-years (n = 500). The RCT in 16- to 26-year-old females reported clinical outcomes. There was little to no difference in the incidence of the combined outcome of high-grade cervical epithelial neoplasia, adenocarcinoma in situ, or cervical cancer between the HPV vaccines (quadrivalent 325/6882, nonavalent 326/6871; OR 1.00, 95% CI 0.85 to 1.16; 13,753 participants; high-certainty evidence). The other two RCTs did not collect data about clinical outcomes. There were slightly more local adverse events with the nonavalent vaccine (905 per 1000) than the quadrivalent vaccine (846 per 1000) (RR 1.07, 95% CI 1.05 to 1.08; 3 RCTs, 15,863 participants; high-certainty evidence). Comparative evidence about serious adverse events in the three RCTs (nonavalent 243/8234, quadrivalent 192/7629; OR 0.60, 95% CI 0.14 to 2.61) was of low certainty, owing to imprecision and indirectness. HPV vaccination for people living with HIV Seven RCTs reported on HPV vaccines in people with HIV, with two small trials that collected data about clinical outcomes. Antibody responses were higher following vaccination with either bivalent or quadrivalent HPV vaccine than with control, and these responses could be demonstrated to have been maintained for up to 24 months in children living with HIV (low-certainty evidence). The evidence about clinical outcomes and harms for HPV vaccines in people with HIV is very uncertain (low- to very low-certainty evidence), owing to imprecision and indirectness.

AUTHORS' CONCLUSIONS

The immunogenicity of two-dose and three-dose HPV vaccine schedules, measured using antibody responses in young females, is comparable. The quadrivalent vaccine probably reduces external genital lesions and anogenital warts in males compared with control. The nonavalent and quadrivalent vaccines offer similar protection against a combined outcome of cervical, vaginal, and vulval precancer lesions or cancer. In people living with HIV, both the bivalent and quadrivalent HPV vaccines result in high antibody responses. For all comparisons of alternative HPV vaccine schedules, the certainty of the body of evidence about serious adverse events reported during the study periods was low or very low, either because the number of events was low, or the evidence was indirect, or both. Post-marketing surveillance is needed to continue monitoring harms that might be associated with HPV vaccines in the population, and this evidence will be incorporated in future updates of this review. Long-term observational studies are needed to determine the effectiveness of reduced-dose schedules against HPV-related cancer endpoints, and whether adopting these schedules improves vaccine coverage rates.

The Path to Perfect Pediatric Posology - Drug Development in Pediatrics

Reluctance to enroll pediatric subjects in clinical trials has left gaps in information about dosing, safety, and efficacy of medications. Pharmacotherapeutic information for pediatric patients may be available for only a small range of ages and may be deficient, as children respond differently as they grow and mature from prematurity to adolescence. Current regulations, however, require early planning for the participation of children in drug development, as pediatric plans must be submitted at the end of phase 1 (European Union) or the end of phase 2 (United States). These plans are extensive, outlining planned studies, subjects to be enrolled, dose and dosage form justification, planned observations, and statistical analysis as well as planned modeling, simulation, and extrapolation analyses. The extent to which efficacy information in adults can be extrapolated to children depends on how similar the disease is in adults and each of the 5 pediatric age groups. Extrapolation may not be possible for conditions that do not occur in adults, requiring a complete development plan in adults, or extrapolation may be complete because of similar pathology and response to treatment. Pharmacokinetic and safety information cannot be extrapolated and must be collected in children of all ages, unless a waiver is granted. Physiologically based pharmacokinetic modeling, optimal design, population pharmacokinetics, and scavenged samples are all examples of new methodologies being used to study pediatric therapeutics. Clinicaltrials.gov and EU Clinical Trials registry are good sources of results of pediatric trials, although sponsors are also working toward prompt publication of study results in peer-reviewed journals.

Long-term Immunogenicity and Safety of the AS04-adjuvanted Human Papillomavirus-16/18 Vaccine in Four- to Six-year-old Girls: Three-year Follow-up of a Randomized Phase III Trial

BACKGROUND

The burden of human papillomavirus (HPV) diseases is high in Latin America. HPV vaccines licensed from 2006 onwards offer protection against most HPV-related cancers, especially when introduced into national immunization programs. Barriers to optimal vaccine uptake are, however, lowering the impact of adolescent HPV vaccination programs. Immunization of children might overcome these barriers and be a strategy of choice for some countries.

METHODS

This multicenter phase III randomized, controlled, single-blind study (NCT01627561) was conducted in Colombia, Mexico and Panama to assess safety and immunogenicity of 2-dose vaccination with AS04-adjuvanted HPV-16/18 vaccine in girls 4-6 years of age. We report safety outcomes and anti-HPV-16/18 antibody titers measured by enzyme-linked immunosorbent assay in HPV-vaccinated girls that were followed over a 36-month period.

RESULTS

Over 36 months (ie, 30 months after the second vaccine dose), among 74 girls included in the HPV group, 1 serious adverse event unrelated to vaccination has been reported. No withdrawal because of (serious) adverse events has been reported. At month 36, all girls in the per-protocol-cohort were still seropositive for anti-HPV-16 and anti-HPV-18 with geometric mean concentrations of 1680.6 and 536.4 enzyme-linked immunosorbent assay units/mL, respectively.

CONCLUSIONS

The AS04-adjuvanted HPV-16/18 vaccine administered according to a 2-dose schedule to girls 4-6 years of age induced a high and sustained immunologic response with an acceptable safety profile during the 30 months following vaccination.

A ten-year study of immunogenicity and safety of the AS04-HPV-16/18 vaccine in adolescent girls aged 10-14 years

This study assessed long-term immunogenicity and safety following 3 doses of AS04-adjuvanted human papillomavirus (HPV)-16/18 L1 virus-like particle (VLP) vaccine in females 10–14 years old. Girls included in the immunogenicity subset in the primary controlled, observer-blinded, randomized study (NCT00196924) who received 3 doses were invited for a 10-year follow-up (NCT00316706 and NCT00877877). Serum antibody responses against HPV-16/18 (vaccine types) and HPV-31/45 (non-vaccine types) were measured by enzyme-linked immunosorbent assay (ELISA) using type-specific VLP as coating antigens. Serious adverse events (SAEs) and pregnancy information were recorded. At Month (M) 120, all subjects (N = 418, according-to-protocol immunogenicity cohort) were seropositive for anti-HPV-16/18 antibodies. Geometric mean titers (GMTs) were 1589.9 ELISA Units [EU]/mL (95% confidence interval [CI]: 1459.8–1731.6) for anti-HPV-16 and 597.2 EU/mL (95% CI: 541.7–658.5) for anti-HPV-18 in subjects seronegative at baseline for the type analyzed. Post hoc mathematical modeling predicted a durability ≥50 years for anti-HPV-16 and anti-HPV-18. For the non-vaccine humoral type response, all initially seronegative subjects had seroconverted at M7, with anti-HPV-31 GMT of 2030.5 EU/mL (95% CI: 1766.2–2334.4) and anti-HPV-45 GMT of 2300.8 EU/mL (95% CI: 2036.8–2599.0). At M120, 87.7% and 85.1% remained seropositive for anti-HPV-31 with GMT of 242.9 EU/mL (95% CI: 201.4–293.0) and anti-HPV-45 with GMT of 204.7 EU/mL (95% CI: 170.0–246.6). During the 10-year follow-up, no SAEs or abnormal pregnancy outcomes were causally related to vaccination. Three doses of the AS04-HPV-16/18 vaccine induced high and sustained antibody response against HPV-16,18,31 and 45 in girls aged 10–14 years during the 10-year follow-up, with an acceptable long-term safety profile.

Persistence of Immunity When Using Different Human Papillomavirus Vaccination Schedules and Booster-Dose Effects 5 Years After Primary Vaccination

Background

There are limited data regarding the duration of immunity induced by different human papillomavirus (HPV) vaccination schedules and the immunogenicity of a booster dose of both bivalent HPV vaccine (bHPV) or quadrivalent HPV vaccine (qHPV).

Methods

Follow-up of a nonrandomized clinical trial to evaluate the 5-year antibody persistence of the bHPV in girls (age, 9-10 years) and women (age, 18-24 years). Noninferiority of the 2-dose versus 3-dose schedule among girls was evaluated at months 54 (n = 639) and 64 (n = 990). Girls vaccinated with a 2-dose schedule of bHPV or qHPV received a booster dose of either vaccine at month 61. Immunogenicity was measured using a virus-like particle-based enzyme-linked immunosorbent assay. Geometric mean titers (GMTs) for HPV16/18 were estimated after stratification by vaccination schedule and age group.

Results

At months 54 and 64, the 2-dose schedule remained noninferior to the 3-dose schedule. GMTs remained above natural infection levels across all age groups up to 64 months. After the booster, anti-HPV16/18 GMTs increased exponentially with the same pattern, regardless of vaccine administered. No safety concerns were identified with the booster dose.

Conclusions

A 2-dose schedule is highly immunogenic in girls, suggesting a high immune memory. Thus, a booster dose is likely to be unprofitable, considering the low global immunization coverage.

Clinical Trials Registration

NCT01717118.

Persistence of immune response following bivalent HPV vaccination: A follow-up study among girls routinely vaccinated with a two-dose schedule

BACKGROUND

In this cohort study, we examined antibody levels and avidity after a two-dose schedule (0, 6 months) of the bivalent HPV-vaccine in girls routinely vaccinated in the Dutch HPV-vaccination program, up to 2 years following vaccination.

METHODS

A blood sample at 7, 12 and 24 months after the first dose and questionnaire data were collected (n = 56). HPV type-specific antibody concentrations (lU/ml) against seven types (HPV16/18/31/33/45/52/58) were assessed using a validated virus-like particles (VLP) multiplex immunoassay. Avidity was tested using a modification of this assay.

RESULTS

Seropositivity for vaccine types HPV 16 and 18 was 100% up to month 24, but declined for HPV-types 31/33/45/52/58, although not statistically significant for HPV45. All Geometric Mean Concentrations (GMCs) declined by months 12 and 24, but remained high for HPV16/18. Between month 7 and 12, GMCs declined more for other types. High avidity antibodies were induced up to 24 months for vaccine types (75%, 76-78% and 81-82% at months 7, 12 and 24, respectively), but for other types antibody avidity was 16-29% at month 7, 20-32% at month 12 and 19-32% at month 24.

CONCLUSIONS

GMCs declined over time for HPV-types 16/18/31/33/45/52/58, but remained high for vaccine-types HPV16/18 up to 24 months of follow-up. Antibody avidity was >75% for vaccine types but <35% for other HPV-types. Further follow-up of this cohort will provide insight into antibody and avidity kinetics over time.

[Alternative HPV vaccination schedules in Latin America]

In 2008, the first HPV vaccination program in Latin America started in Panama, targeting girls aged 10-11 years with a 3-dose vaccine schedule, an initiative that was to be followed by other Latin American countries after local feasibility and population acceptability evaluations were completed. A 3-dose vaccine regimen over six months was originally chosen for HPV vaccines, copying the Hepatitis B vaccine schedule (0, 1-2, 6 months). Alternative vaccine schedules have been proposed afterwards based on: i) noninferior immunogenicity or immune response levels compared to those at which clinical efficacy has been proven (i.e., those observed in a 3-dose HPV vaccine schedule in women aged 15-26), and, ii) proven efficacy in clinical trials and/or effectiveness among women who were provided less than three doses due to a lack of adherence to a 3-dose vaccine schedule. In 2014, based on the available evidence and the potential increase in coverage by expansion of vaccination target groups, particularly in low and middle income countries (LMIC), the World Health Organization recommended a 2-dose schedule with at least a 6-month interval between doses for females up to 15 years of age and a 3-dose schedule for older women. More recently, it has been suggested that 1-dose HPV vaccination schemes may provide enough protection against HPV infection and may speed up the introduction of HPV vaccination in LMIC, where most needed.

Immune Response to Human Papillomavirus One Year after Prophylactic Vaccination with AS04-Adjuvanted HPV-16/18 Vaccine: HPV-Specific IgG and IgA Antibodies in the Circulation and the Cervix

Objective:

This study was designed to describe the course of IgG/IgA responses in cervical secretions and in serum one year after the first dose of intramuscular administration of the HPV16/18 AS04-adjuvant vaccine.

Methods:

Blood and cervical mucus samples were collected for immunologic assays, 7 months after the first doses and 1 year following the last boost vaccination (month 7) by enzyme linked immunosorbent assay (ELISA). The detection of IgG and IgA anti-HPV/VLP was developed for this purpose.

Result:

A total of 100% of serum samples were IgG antibody positive at a titer of 1:100 at both time periods and decreased according to the serum dilution. For serum IgA antibody, 95% were positive one month after vaccination and 79% were positive 1 year later. Similar results were observed with the cervical samples positive for both IgG and IgA antibodies at one month and decreasing after 1 year to 33% and 29%. The median absorbance in serum and the cervix for IgG and IgA anti-HPV-VLP antibodies was significantly higher at one month after vaccination when compared to 1 year post-vaccination (P<0.0001).

Conclusion:

Immune responses were significant one year after immunization, however it decreased in cervical and serum samples when compared to levels observed one month after the last dose. This suggests that a vaccine booster may be necessary to increase antibody titers.

Opportunities and challenges for human papillomavirus vaccination in cancer

The discovery of genotype 16 as the prototype oncogenic human papillomavirus (HPV) initiated a quarter century of laboratory and epidemiological studies that demonstrated their necessary, but not sufficient, aetiological role in cervical and several other anogenital and oropharyngeal cancers. Early virus-induced immune deviation can lead to persistent subclinical infection that brings the risk of progression to cancer. Effective secondary prevention of cervical cancer through cytological and/or HPV screening depends on regular and widespread use in the general population, but coverage is inadequate in low-resource settings. The discovery that the major capsid antigen L1 could self-assemble into empty virus-like particles (VLPs) that are both highly immunogenic and protective led to the licensure of several prophylactic VLP-based HPV vaccines for the prevention of cervical cancer. The implementation of vaccination programmes in adolescent females is underway in many countries, but their impact critically depends on the population coverage and is improved by herd immunity. This Review considers how our expanding knowledge of the virology and immunology of HPV infection can be exploited to improve vaccine technologies and delivery of such preventive strategies to maximize reductions in HPV-associated disease, including incorporation of an HPV vaccine covering oncogenic types within a standard multitarget paediatric vaccine.

Safety and Immunogenicity of the HPV-16/18 AS04-adjuvanted Vaccine in 4-6-year-old Girls: Results to Month 12 From a Randomized Trial

BACKGROUND

The burden of cervical cancer caused by human papillomavirus (HPV) is high in Latin America. The suboptimal HPV vaccination coverage in adolescents could be improved by pediatric immunization. HPV vaccination has not yet been reported in girls <9 years of age.

METHODS

This ongoing phase III, controlled, randomized, single-blind, multicenter study conducted in Colombia, Mexico and Panama (NCT01627561) evaluated the safety and immunogenicity of AS04-HPV-16/18 vaccine in 4-6-year-old girls. Healthy girls (randomized 1:1) received either 2 doses of AS04-HPV-16/18 vaccine (HPV group, N=74) or 1 dose of each measles-mumps-rubella and diphtheria-tetanus-acellular-pertussis vaccines (control group, N=74) 6 months apart. We report the safety and serum anti-HPV-16 and anti-HPV-18 antibodies (measured by enzyme-linked immunosorbent assay) up to 6 months postvaccination, that is, month (M) 12.

RESULTS

Injection site pain was the most frequently reported solicited local symptom in HPV vaccinees. The incidence of other solicited and unsolicited symptoms after each vaccination was similar between the HPV and control group. Until M12, 1 girl in the HPV group and 2 in the control group reported serious adverse events; all serious adverse events were assessed as unrelated to study vaccines. No potential immune-mediated diseases were identified. All girls seroconverted for both antigens after 2 doses of AS04-HPV-16/18. In initially seronegative girls, anti-HPV-16 geometric mean concentrations were 20080.0 enzyme-linked immunosorbent assay units (EU)/mL at M7 and 3246.5 EU/mL at M12; anti-HPV-18 geometric mean concentrations were 10621.8 EU/mL at M7 and 1216.6 EU/mL at M12.

CONCLUSIONS

Two-dose vaccination with AS04-HPV-16/18 was well tolerated and induced adequate antibody responses in 4-6-year-old girls.

Antibody responses among adolescent females receiving two or three quadrivalent human papillomavirus vaccine doses at standard and prolonged intervals

BACKGROUND

The originally recommended dosing schedule, 0, 2, 6 months, for the 3-dose quadrivalent human papillomavirus vaccine (4vHPV) was often not followed, resulting in longer than recommended intervals between doses and interest in the effect of prolonged intervals. Recent two-dose recommendations require investigations into the effect of delaying dose 2.

METHODS

This multi-site, prospective study enrolled healthy 9-17 year old girls (n = 1321) on the day of or within 28 days following a third dose of 4vHPV vaccination. Antibody titers to 4vHPV types were measured at one and six months post-dose 3 from all participants and post-dose 2 from participants who were on time for dose 3. To compare antibody responses, participants were categorized into groups: second and third doses on time (control group); on-time dose 2, substantially late dose 3 (group 2); substantially late dose 2, on-time dose 3 (group 3); both doses substantially late (group 4). Analyses compared age-adjusted geometric mean titers (GMTs) at one-month and six-months post-dose 3, effect of delaying the second dose, and two versus three doses as well as post-dose 2 GMTs, stratified by age.

RESULTS

Compared to on-time dosing, one-month post-dose 3 GMTs were non-inferior in groups 2, 3, and 4 and were superior in group 2. Six month post-dose 3 GMTs were superior in groups 2, 3, and 4 for each genotype, except HPV 18 in group 3. Age-adjusted post does 2 titers were significantly lower than post-dose 3 titers when dose 2 was on time but were significantly higher when dose 2 was substantially late. Participants ≥15 years old had no difference in post-dose 2 titers compared to <15 year olds when dose 2 was substantially delayed.

CONCLUSIONS

Prolonged intervals between doses do not appear to diminish and may enhance antibody response to 4vHPV. ClinicalTrials.gov (NCT00524745).