Evaluation of immune response following one dose of an AS03A-adjuvanted H1N1 2009 pandemic influenza vaccine in Japanese adults 65 years of age or older

Adjuvanted influenza vaccines

In spite of current influenza vaccines being immunogenic, evolution of the influenza virus can reduce efficacy and so influenza remains a major threat to public health. One approach to improve influenza vaccines is to include adjuvants; substances that boost the immune response. Adjuvants are particularly beneficial for influenza vaccines administered during a pandemic when a rapid response is required or for use in patients with impaired immune responses, such as infants and the elderly. This review outlines the current use of adjuvants in human influenza vaccines, including what they are, why they are used and what is known of their mechanism of action. To date, six adjuvants have been used in licensed human vaccines: Alum, MF59, AS03, AF03, virosomes and heat labile enterotoxin (LT). In general these adjuvants are safe and well tolerated, but there have been some rare adverse events when adjuvanted vaccines are used at a population level that may discourage the inclusion of adjuvants in influenza vaccines, for example the association of LT with Bell's Palsy. Improved understanding about the mechanisms of the immune response to vaccination and infection has led to advances in adjuvant technology and we describe the experimental adjuvants that have been tested in clinical trials for influenza but have not yet progressed to licensure. Adjuvants alone are not sufficient to improve influenza vaccine efficacy because they do not address the underlying problem of mismatches between circulating virus and the vaccine. However, they may contribute to improved efficacy of next-generation influenza vaccines and will most likely play a role in the development of effective universal influenza vaccines, though what that role will be remains to be seen.

Low hemagglutinin antigen dose influenza vaccines adjuvanted with AS03 alter the long-term immune responses in BALB/c mice

We investigated the long-term immune profiles of dose-sparing, AS03-adjuvanted vaccines compared to a traditional high-dose, unadjuvated influenza vaccine formulation. BALB/c mice received 2 IM injections of influenza A/Uruguay/716/2007 (H3N2) split vaccine antigen: high-dose (HD) (3 µg hemagglutinin (HA)/dose) or low-dose (LD) formulations (0.03 µg or 0.003 µg HA) with AS03 and were followed to 34 weeks post-boost (pb). We examined serologic responses, spleen and bone marrow (BM) HA-specific antibody-secreting cells (ASCs) by ELISpot, influenza-specific cytokine/chemokine production in re-stimulated splenocytes by multiplex ELISA, and antigen-specific CD4+ T cells that express cytokines (IL-2, IFNγ, TNFα and IL-5) by flow cytometry. All formulations elicited robust serum antibody titers that persisted for at least 34 weeks. The number of antigen-specific ASCs in the spleen and BM were higher in the 2 LD +AS03 groups, but despite having fewer ASCs, the average spot size in the HD-unadjuvanted group was larger at later time-points, suggesting greater antibody production per cell. Striking differences in the long-term profiles induced by the different vaccine formulations may contribute to these different ASC profiles. The HD-unadjuvanted vaccine elicited strong Th2 cytokines during the first 6 weeks pb but LD+AS03 groups generated broader, more durable responses at later timepoints. Finally, the 0.03 µg HA+AS03 group generated the greatest number of antigen-specific CD4+ T cells and the highest percentage of poly-functional cells that expressed 2 or more cytokines. Although all of the tested vaccines induced durable antibody responses, we show that different vaccine formulations (dose-sparing, adjuvant) generate distinct long-term immune profiles. Furthermore, our data suggest that the different profiles may be generated through unique mechanisms.

Single dose vaccination of the ASO3-adjuvanted A(H1N1)pdm09 monovalent vaccine in health care workers elicits homologous and cross-reactive cellular and humoral responses to H1N1 strains

Healthcare workers (HCW) were prioritized for vaccination during the 2009 influenza A(H1N1)pdm09 pandemic. We conducted a clinical trial in October 2009 where 237 HCWs were immunized with a AS03-adjuvanted A(H1N1)pdm09 monovalent vaccine. In the current study, we analyzed the homologous and cross-reactive H1N1 humoral responses using prototype vaccine strains dating back to 1977 by the haemagglutinin inhibition (HI), single radial hemolysis SRH), antibody secreting cell (ASC) and memory B cell (MBC) assays. The cellular responses were assessed by interferon-γ (IFN-γ) ELISPOT and by intracellular staining (ICS) for the Th1 cytokines IFN-γ, interleukin-2 (IL-2) and tumor necrosis factor-α (TNF-α). All assays were performed using blood samples obtained prior to (day 0) and 7, 14 and 21 d post-pandemic vaccination, except for ASC (day 7) and ICS (days 0 and 21). Vaccination elicited rapid HI, SRH and ASC responses against A(H1N1)pdm09 which cross reacted with seasonal H1N1 strains. MBC responses were detected against the homologous and seasonal H1N1 strains before vaccination and were boosted 2 weeks post-vaccination. An increase in cellular responses as determined by IFN-γ ELISPOT and ICS were observed 1–3 weeks after vaccination. Collectively, our data show that the AS03-adjuvanted A(H1N1)pdm09 vaccine induced rapid cellular and humoral responses against the vaccine strain and the response cross-reacted against prototype H1N1 strains dating back to 1977.

Antibody Persistence in Adults Two Years after Vaccination with an H1N1 2009 Pandemic Influenza Virus-Like Particle Vaccine

The influenza virus is a human pathogen that causes epidemics every year, as well as potential pandemic outbreaks, as occurred in 2009. Vaccination has proven to be sufficient in the prevention and containment of viral spreading. In addition to the current egg-based vaccines, new and promising vaccine platforms, such as cell culture-derived vaccines that include virus-like particles (VLPs), have been developed. VLPs have been shown to be both safe and immunogenic against influenza infections. Although antibody persistence has been studied in traditional egg-based influenza vaccines, studies on antibody response durations induced by VLP influenza vaccines in humans are scarce. Here, we show that subjects vaccinated with an insect cell-derived VLP vaccine, in the midst of the 2009 H1N1 influenza pandemic outbreak in Mexico City, showed antibody persistence up to 24 months post-vaccination. Additionally, we found that subjects that reported being revaccinated with a subsequent inactivated influenza virus vaccine showed higher antibody titres to the pandemic influenza virus than those who were not revaccinated. These findings provide insights into the duration of the antibody responses elicited by an insect cell-derived pandemic influenza VLP vaccine and the possible effects of subsequent influenza vaccination on antibody persistence induced by this VLP vaccine in humans.

A dose-ranging study of MF59(®)-adjuvanted and non-adjuvanted A/H1N1 pandemic influenza vaccine in young to middle-aged and older adult populations to assess safety, immunogenicity, and antibody persistence one year after vaccination

BACKGROUND

During development of an A/H1N1 pandemic influenza vaccine, this study was performed to identify the antigen and adjuvant content which would provide optimal antibody response and persistence in adults and the elderly. Dose-sparing strategies, such as inclusion of adjuvants, are critical in ensuring the widest possible population coverage in the event of an influenza pandemic, despite a limited global capacity for vaccine manufacture.

METHODS

Healthy subjects aged 18-64 years (n = 1240) and ≥65 years (n = 1352) were vaccinated with 1 of 8 investigational vaccine formulations varying in antigen quantity (3.75 µg to 30 µg of hemagglutinin) and MF59(®) adjuvant (none, half dose, or full dose). All subjects received 2 vaccine doses administered 3 weeks apart. Antibody response was assessed by hemagglutination inhibition assay 1 and 3 weeks after administration of first and second doses. Antibody persistence was assessed after 6 and 12 mo. Vaccine safety was monitored over 12 mo.

RESULTS

All 8 investigational A/H1N1 vaccine formulations were well tolerated, and rapidly induced high antibody titers which met all of the Center for Biologics Evaluation and Research (CBER) and Committee for Medicinal Products for Human Use (CHMP) licensure criteria 3 weeks after one dose. The highest antibody titers were observed in participants vaccinated with higher quantities of antigen and adjuvant.

CONCLUSION

A single vaccine dose containing 3.75 µg of A/California/7/2009 (H1N1) antigen with MF59 adjuvant was identified as optimal for young to middle-aged (18-64 years) and older (≥65 years) adult populations.

Impact of anti-rheumatic treatment on immunogenicity of pandemic H1N1 influenza vaccine in patients with arthritis

Introduction

An adjuvanted pandemic H1N1 influenza (pH1N1) vaccine (Pandemrix®) was reported as highly immunogenic resulting in seroconversion in 77 to 94% of adults after administration of a single dose. The aim of the study was to investigate the impact of different anti-rheumatic treatments on antibody response to pH1N1 vaccination in patients with rheumatoid arthritis (RA) and spondylarthropathy (SpA).

Methods

Patients with arthritis (n = 291; mean age 57 years, 64% women) participated. Hemagglutination inhibition (HI) assay was performed on blood samples drawn before and after a mean (SD) of 8.3 (4) months following vaccination. A positive immune response i.e. seroconversion was defined as negative prevaccination serum and postvaccination HI titer ≥40 or a ≥4-fold increase in HI titer. All patients were divided into predefined groups based on diagnosis (RA or SpA) and ongoing treatment: methotrexate (MTX), anti-tumor necrosis factor (anti-TNF) as monotherapy, MTX combined with anti-TNF, other biologics (abatacept, rituximab, tocilizumab) and non-steroidal anti-inflammatory drugs (NSAIDs)/analgesics. Predictors of positive immune response were studied using logistic regression analysis.

Results

The percentage of patients with positive immune response in the different treatment groups was: 1. RA on MTX 42%; 2. RA on anti-TNF monotherapy 53%; 3. RA on anti-TNF + MTX 43%; 4. RA on other biologics (abatacept 20%, rituximab 10% and tocilizumab 50%); 5. SpA on anti-TNF monotherapy 76%; 6. SpA on anti-TNF + MTX 47%; and 7. SpA on NSAIDs/analgesics 59%. RA patients on rituximab had significantly lower (P < 0.001) and SpA on anti-TNF monotherapy significantly better response rates compared to other treatment groups (P 0.001 to 0.033). Higher age (P < 0.001) predicted impaired immune response. Antibody titers 3 to 6 months after vaccination was generally lower compared to those within the first 3 months but no further decrease in titers were observed 6 to 22 months after vaccination.

Conclusions

Rituximab treatment severely reduced antibody response to pH1N1 influenza vaccine. The other treatment groups showed acceptable antibody responses. Protective antibody titers could be detected up to 22 months after vaccination in the current patient population, with the exception of rituximab treated patients.

Extended antigen sparing potential of AS03-adjuvanted pandemic H1N1 vaccines in children, and immunological equivalence of two formulations of AS03-adjuvanted H1N1 vaccines: results from two randomised trials

Background

Pandemic influenza vaccine manufacturing capacity and distribution agility is enhanced through the availability of equivalent antigen-sparing vaccines. We evaluated equivalence in terms of immunogenicity between GlaxoSmithKline Vaccines’ A/California/7/2009 (H1N1)v-like-AS03 vaccines manufactured in Dresden (D-Pan), and Quebec (Q-Pan).

Methods

In two studies, 334 adults 18-60 years of age received 2 doses of D-Pan or Q-Pan containing 3.75 μg haemagglutinin antigen (HA) adjuvanted with AS03_A administered 21 days apart, and 209 children 3-9 years of age received 1 reduced dose of D-Panor Q-Pan (0.9 μg HA) or Q-Pan (1.9 μg HA) with AS03_B. Haemagglutination inhibition (HI) titres were assessed before and 21 days post-vaccination. HI persistence was assessed after 12 months in adults and 6 months in children.

Results

Pre-defined criteria for immunological equivalence of Q-Pan versus D-Pan were achieved in both populations. After one vaccine dose, ≥97.6% of adults and children had HI titres ≥1:40, with increases in titre ≥25.7-fold. CHMP and CBER regulatory acceptance criteria for influenza vaccines were exceeded by all groups in both studies at Day 21. In adults,the percentage with HI titres ≥1:40 at Month 12 was 82.9% (Q-Pan) and 84.0% (D-Pan). In children, the percentages at Month 6 were 75.3.3% (Q-Pan0.9), 85.1% (D-Pan0.9) and 79.3% (Q-Pan1.9). Safety profile of the study vaccines was consistent with previously published data.

Conclusion

Two studies indicate that A/California/7/2009 (H1N1)v-like HA manufactured at two sites and combined with AS03 are equivalent in terms of immunogenicity in adults and children and highly immunogenic. Different HA doses elicited an adequate immune response through 180 days post-vaccination in children 3-9 years of age.

Trial registration

ClinicalTrials.gov: NCT00979407 and NCT01161160.

Long-term immunogenicity of an AS03-adjuvanted influenza A(H1N1)pdm09 vaccine in young and elderly adults: an observer-blind, randomized trial

BACKGROUND

This study (NCT00979602) evaluated the immunogenicity and relative protective efficacy of one dose of influenza A(H1N1)pdm09 vaccine with or without AS03 (an α-tocopherol oil-in-water emulsion based Adjuvant System).

METHODS

Four thousands and forty-eight healthy adults aged ≥ 18 years were randomized (1:1) to receive one dose of either the adjuvanted split virion (3.75 μg hemagglutinin antigen [HA]/AS03) or non-adjuvanted (15 μg HA) vaccine. Hemagglutination inhibition [HI] antibody response was evaluated before vaccination and at Days 21, 42 and 182 (Month 6). Safety of the study vaccines was evaluated during the entire study duration.

RESULTS

At Day 21, both study vaccines induced HI immune responses meeting the US regulatory criteria in subjects 18-64 years (seroprotection rate [SPR]: 98.0% [97.1-98.6]; seroconversion rate [SCR]: 89.7% [88.0-91.2] in the AS03-adjuvanted group; SPR: 91.4% [89.9-92.8]; SCR: 74.6% [72.3-76.9] in the non-adjuvanted group) and >64 years of age (SPR: 86.0% [82.5-89.0]; SCR: 75.3% [71.1-79.2] in the AS03-adjuvanted group; SPR: 69.1% [64.6-73.3]; SCR: 56.7% [52.0-61.3] in the non-adjuvanted group). The AS03-adjuvanted vaccine induced higher HI geometric mean titers than the non-adjuvanted vaccine at all time points. At Month 6, only subjects 18-64 years of age from both vaccine groups still met the US regulatory criteria (SPR: 82.1% [80.0-84.1]; SCR: 62.3% [59.6-64.8] in the AS03-adjuvanted group; SPR: 75.3% [72.9-77.5]; SCR: 53.7% [51.0-56.4] in the non-adjuvanted group). Protective efficacy was not evaluated due to low number of RT-qPCR-confirmed A(H1N1)pdm09 influenza cases. Through Month 12, 216 serious adverse events (in 157 subjects: 84 in the AS03-adjuvanted and 73 in the non-adjuvanted group) and 12 potentially immune mediated diseases (5 in the AS03-adjuvanted and 7 in the non-adjuvanted group) were reported.

CONCLUSION

A single dose of either adjuvanted or non-adjuvanted influenza A(H1N1)pdm09 vaccine induced protective HI antibody levels against the A/California/7/2009 strain that persisted through Month 6 in the 18-64 years population.

Long-term persistence of humoral and cellular immune responses induced by an AS03A-adjuvanted H1N1 2009 influenza vaccine: an open-label, randomized study in adults aged 18-60 years and older

This manuscript presents data on the persistence of Hemagglutination Inhibition (HI) immune response against the A/California/7/2009 strain, six and 12 mo after adults received one dose (n = 138) or two doses (n = 102; 21 d apart) of a 3.75 µg Hemagglutinin antigen AS03-adjuvanted H1N1 2009 vaccine (NCT00968526). Two hundred forty subjects (18-60 y: 120;>60 y: 120) were vaccinated. Immunogenicity end points were based on the European licensure criteria for pandemic influenza vaccines. Exploratory analyses assessed the cell-mediated immune response (CMI) up to Month 12 and the influence of previous influenza vaccination on persistence of immune response. At Month 6, the CHMP criteria were met in subjects aged 18-60 y who received one or two vaccine doses and in subjects aged>60 y who received two vaccine doses. At Month 12, the CHMP criteria were met only in subjects aged 18-60 y who received two vaccine doses. Persistence of HI immune response against the vaccine strain was higher in subjects without prior influenza vaccination. Exploratory analyses showed that two doses of the H1N1 2009 vaccine induced persistence of H1N1-specific CD4+ T cells up to Month 6 and memory B cells up to Month 12. In conclusion, HI immune responses persisted up to 12 mo after vaccination with one-dose and two-dose regimens of the AS03-adjuvanted 3.75 µg HA H1N1 2009 pandemic influenza vaccine, although not all three CHMP guidance criteria for both groups were met at Month 6 and Month 12. The CD4+ T cell and B cell responses also persisted up to Month 12.