Maria Lattanzi

MF59 Adjuvant Enhances Diversity and Affinity of Antibody-Mediated Immune Response to Pandemic Influenza Vaccines

Adjuvant use improves the quality and quantity of the immune response to pandemic influenza vaccines. A Shot in the Arm for the Flu Vaccine Because flu vaccine production begins months before the flu season, vaccine producers and world health officials have to guess which strains will predominate in a coming year. Although they’re frequently right, sometimes a dark horse arises that wasn’t predicted, and vaccine makers have to play catch-up. Speed is of the essence when attempting to prevent a pandemic, and limited supplies could hinder a worldwide vaccination campaign, preventing the broad coverage that protects even unvaccinated people. Khurana et al. report that the use of an oil-in-water adjuvant, MF59, improves the magnitude, robustness, and strength of the immune response to pandemic flu vaccines and may decrease the amount of antigen required for each dose. The authors looked at the quantitative and qualitative effects of MF59 on the antibody response in patients from various age groups who were vaccinated with the swine-origin H1N1 flu vaccine. They found that in adults and children who had been either previously vaccinated or exposed to the flu, MF59 increased the diversity and volume of neutralizing antibody responses to the flu vaccine. Antibody responses were slightly different in toddlers, suggesting that there may be distinct requirements for activating primary and recall antibody responses. MF59 also increased the strength with which these antibodies bound to the flu virus. These results support the use of adjuvants with flu vaccinations. Such a strategy could help expand coverage and decrease morbidity in the event of pandemic influenza and give vaccine makers the edge in a game of catch-up with dark horses. Oil-in-water adjuvants have been shown to improve immune responses against pandemic influenza vaccines as well as reduce the effective vaccine dose, increasing the number of doses available to meet global vaccine demand. Here, we use genome fragment phage display libraries and surface plasmon resonance to elucidate the effects of MF59 on the quantity, diversity, specificity, and affinity maturation of human antibody responses to the swine-origin H1N1 vaccine in different age groups. In adults and children, MF59 selectively enhanced antibody responses to the hemagglutinin 1 (HA1) globular head relative to the more conserved HA2 domain in terms of increased antibody titers as well as a more diverse antibody epitope repertoire. Antibody affinity, as inferred by greatly diminished (≥10-fold) off-rate constants, was significantly increased in toddlers and children who received the MF59-adjuvanted vaccine. Moreover, MF59 also improved antibody affinity maturation after each sequential vaccination against avian H5N1 in adults. For both pandemic influenza vaccines, there was a close correlation between serum antibody affinity and virus-neutralizing capacity. Thus, MF59 quantitatively and qualitatively enhances functional antibody responses to HA-based vaccines by improving both epitope breadth and binding affinity, demonstrating the added value of such adjuvants for influenza vaccines.

mTOR inhibition improves immune function in the elderly

mTOR inhibition by RAD001 improves immune responses in elderly volunteers receiving an influenza vaccination. mTOR and Human Aging Inhibition of mTOR signaling extends life span and delays the onset of aging-related diseases in all species studied to date. These findings suggest that the mTOR pathway regulates aging. However, it is unknown if mTOR inhibition has beneficial effects on aging in humans. To begin to address this question, Mannick et al. evaluated the effects of the mTOR inhibitor RAD001 on the decline in immune function that occurs during aging in humans. Their findings suggest that RAD001 improved immune function in elderly volunteers as assessed by response to influenza vaccination. It remains to be determined whether mTOR inhibition improves additional aging-related conditions in humans. Inhibition of the mammalian target of rapamycin (mTOR) pathway extends life span in all species studied to date, and in mice delays the onset of age-related diseases and comorbidities. However, it is unknown if mTOR inhibition affects aging or its consequences in humans. To begin to assess the effects of mTOR inhibition on human aging-related conditions, we evaluated whether the mTOR inhibitor RAD001 ameliorated immunosenescence (the decline in immune function during aging) in elderly volunteers, as assessed by their response to influenza vaccination. RAD001 enhanced the response to the influenza vaccine by about 20% at doses that were relatively well tolerated. RAD001 also reduced the percentage of CD4 and CD8 T lymphocytes expressing the programmed death-1 (PD-1) receptor, which inhibits T cell signaling and is more highly expressed with age. These results raise the possibility that mTOR inhibition may have beneficial effects on immunosenescence in the elderly.

Clinical Efficacy of Cell Culture—Derived and Egg-Derived Inactivated Subunit Influenza Vaccines in Healthy Adults

BACKGROUND More efficient methods are needed to manufacture influenza vaccines. This trial compared the efficacy of cell culture-derived influenza vaccine (CCIV) and egg-derived trivalent inactivated vaccine (TIV) with placebo against laboratory-confirmed influenza illness in healthy adults in the United States, Finland, and Poland during the 2007-2008 influenza season. METHODS A total of 11,404 study participants aged 18-49 years were randomized equally to receive CCIV (Optaflu; n = 3828), TIV (Agrippal; n = 3676), or placebo (n = 3900). Each participant was observed during a 6-month study surveillance period. Nasal and throat swabs for virus isolation and characterization were collected from all patients with influenza-like illness. Vaccine immunogenicity was evaluated in a subset of 1045 participants. RESULTS Efficacy of CCIV and TIV against vaccine-like (83.8% [1-sided 97.5% confidence interval [CI] lower limit, 61.0%] and 78.4% [1-sided 97.5% CI lower limit, 52.1%], respectively) and all circulating influenza virus strains (69.5% [1-sided 97.5% CI lower limit, 55.0%] and 63.0% [1-sided 97.5% lower limit, 46.7%], respectively) exceeded the Center for Biologics Evaluation and Research efficacy criteria. Immunogenicity of both vaccines exceeded the Center for Biologics Evaluation and Research licensing criteria. Both vaccines were well tolerated, with similar safety profiles. Most solicited reactions were mild to moderate in severity and transient. No vaccination-related serious adverse events were reported; no withdrawals resulted from vaccine-related adverse events. CONCLUSIONS Both CCIV and TIV were effective in preventing influenza caused by vaccine-like and by all circulating influenza virus strains, were well tolerated, and had good safety profiles. Both vaccines can be considered for annual influenza vaccination campaigns. CLINICAL TRIALS REGISTRATION NCT00630331.

Dose ranging of adjuvant and antigen in a cell culture H5N1 influenza vaccine: Safety and immunogenicity of a phase 1/2 clinical trial

BACKGROUND Dose-sparing strategies and new production technologies will be necessary to produce adequate supplies of vaccines for pandemic influenza. One approach is to include adjuvant, which can reduce the amount of antigen required for immunization and stimulate cross-reactive responses to drifted variants of novel viruses. Dose-sparing studies of adjuvant, itself a finite resource, have not previously been reported for H5N1 vaccine development. METHODOLOGY/PRINCIPAL FINDINGS A total of 753 healthy 18-40-year-old adults were randomized to one of 12 groups (N approximately 60/group) to receive two intramuscular doses, 21 days apart, of 3.75, 7.5 or 15 microg of cell culture grown influenza A/H5N1 hemagglutinin (A/Indonesia/5/2005 (H5N1)/PR-8-IBCDC-RG2), each dose level formulated with 0%, 25%, 50% or 100% of the MF59 dose contained in licensed influenza vaccine. 752 subjects actually received one dose, and 695 a second dose. Serum hemagglutination inhibition and neutralizing antibody levels, were determined before and 21 days after each dose. Safety and reactogenicity were assessed by self-completed diary cards. Nonadjuvanted H5N1 formulations were poorly immunogenic, but antibody responses were significantly enhanced by all doses of MF59 for each antigen level. The 3.75 microg H5N1 containing 50% MF59 satisfied the European criteria for pandemic vaccine licensure. All formulations were well tolerated, although MF59 dose-dependent increases in the frequency of injection site pain were observed. The frequencies of injection site and systemic reactions were lower after receipt of the second dose of vaccine. No vaccine-related SAE was reported. CONCLUSIONS Dose-sparing of both antigen and adjuvant is possible without compromising immunogenicity, while improving reactogenicity and is a promising strategy that will expand the availability of vaccines for global control of pandemic influenza.

Safety and Immunogenicity of a Novel Influenza Subunit Vaccine Produced in Mammalian Cell Culture

BACKGROUND Immunization remains the best prevention strategy for influenza, but production constraints for egg-based influenza vaccines have prompted the development of innovative cell culture manufacturing processes. Here, we describe a novel cell culture-derived influenza vaccine (CCIV) produced in Madin-Darby canine kidney cells. METHODS This phase 3, observer-blind, randomized, multicenter study in Poland compared the immunogenicity of a CCIV and a conventional egg-based vaccine. Participants, stratified by age (adults 18-60 years, n = 1300; elderly persons > or = 61 years, n = 1354), received a single intramuscular vaccination. Immunogenicity was assessed 21 days later by hemagglutination inhibition assay. Reactogenicity was assessed using self-completed diary cards. RESULTS The immunogenicity of CCIV was noninferior to that of the conventional vaccine for all 3 vaccine strains in both age groups, regardless of underlying health status. Both vaccines fulfilled European Union registration criteria and were well tolerated, with similar incidences of solicited local and systemic reactions in both age groups; the only significant difference was an increased frequency of mild or moderate pain with CCIV than the conventional vaccine among adult (22% vs 17%; P < .05) and elderly (9% vs 5%; P < .001) vaccinees. CONCLUSIONS CCIV was well tolerated and highly immunogenic in adults 18 years of age or older. Cell culture may offer greater flexibility of supply during periods of high demand for both seasonal and pandemic vaccines.

Immunogenicity, safety and reactogenicity of a mammalian cell-culture-derived influenza vaccine in healthy children and adolescents three to seventeen years of age.

Background: The safety and immunogenicity of the cell-culture–derived seasonal trivalent influenza vaccine ([CCIV]; Optaflu) has been reported previously in adults and the elderly. In this study, we compared the safety, reactogenicity and immunogenicity of CCIV with a conventional egg-derived trivalent influenza vaccine (TIV) in a healthy pediatric population. Methods: A total of 3604 subjects were randomized to receive 2 doses of CCIV or TIV (3–8 years, n = 2630) at a 28-day interval or a single vaccination (9–17 years, n = 974). Antibody levels on days 1, 29 and 50 were measured by hemaglutination inhibition assay using egg-derived and cell-derived test antigens. Adverse reactions were solicited via memory aids for 7 days after each injection, and unsolicited adverse events/serious adverse events were collected for 6 months postvaccination. Results: Noninferiority of CCIV versus TIV was demonstrated for most immunogenicity measures, particularly by using cell-derived antigen in the hemaglutination inhibition assay. In 3- to 8-year-olds (the primary objective), both CCIV and TIV met all 3 Committee for Medicinal Products for Human Use immunogenicity criteria for A/H1N1 and A/H3N2 strains. Lower immune responses were observed against the B strain, fulfilling Committee for Medicinal Products for Human Use criteria only for geometric mean ratio (TIV, CCIV) and seroconversion rate (TIV, CCIV [cell-derived antigen]). Both CCIV and TIV were safe and well tolerated, with no differences in local and systemic solicited reactions or in unsolicited adverse events/serious adverse events. Conclusion: CCIV produced in mammalian cell culture is a safe, well-tolerated and immunogenic alternative to conventional egg-derived influenza vaccines for children and adolescents.

One dose of an MF59-adjuvanted pandemic A/H1N1 vaccine recruits pre-existing immune memory and induces the rapid rise of neutralizing antibodies.

Protective antibody responses to a single dose of 2009 pandemic vaccines have been observed in the majority of healthy subjects aged more than 3 years. These findings suggest that immune memory lymphocytes primed by previous exposure to seasonal influenza antigens are recruited in the response to A/H1N1 pandemic vaccines and allow rapid seroconversion. However, a clear dissection of the immune memory components favoring a fast response to pandemic vaccination is still lacking. Here we report the results from a clinical study where antibody, CD4+ T cell, plasmablast and memory B cell responses to one dose of an MF59-adjuvanted A/H1N1 pandemic vaccine were analyzed in healthy adults. While confirming the rapid appearance of antibodies neutralizing the A/H1N1 pandemic virus, we show here that the response is dominated by IgG-switched antibodies already in the first week after vaccination. In addition, we found that vaccination induces the rapid expansion of pre-existing CD4+ T cells and IgG-memory B lymphocytes cross-reactive to seasonal and pandemic A/H1N1 antigens. These data shed light on the different components of the immune response to the 2009 H1N1 pandemic influenza vaccination and may have implications in the design of vaccination strategies against future influenza pandemics.

Comparison of half and full doses of an MF59-adjuvanted cell culture-derived A/H1N1v vaccine in Japanese children.

IntroductionThe substantial pandemic (A/H1N1v) influenza disease burden in children highlights the need for effective vaccination. We report the results of modern cell culture technology, lower doses of antigen, and different doses of MF59® adjuvant (Novartis Vaccines, Marburg, Germany), on the immunogenicity and safety profile in a healthy Japanese pediatric population.MethodsA total of 123 children from 6 months to 19 years of age were randomly assigned in a 1:1 ratio to receive, at 21-day intervals, two doses of either 3.75 μg antigen with 50% of the standard MF59 dose (group A) or 7.5 μg antigen and 100% standard MF59 dose (group B). Antibody levels were measured by hemagglutinin inhibition (HI) and microneutralization assays on day 1 and on days 22 and 43 (3 weeks after the first and second vaccinations, respectively). Solicited adverse events were reported for 7 days after each injection and spontaneous events were reported throughout the study period.ResultsAt 3 weeks after the first vaccination, seroprotective HI antibodies (titers ≥40) were observed in 56% and 78% of subjects from groups A and B, respectively; 100% in both groups exhibited HI titers ≥40 after the second dose. The reactogenicity profile was acceptable, with local and systemic reactions described as mainly mild to moderate in severity. Five serious adverse events were reported, but none related to the study vaccine.ConclusionOne dose of cell culture-derived A/H1N1v vaccine containing 7.5 μ g antigen with the full MF59 adjuvant dose was immunogenic and well tolerated in healthy Japanese children, meeting all three European Union Committee for Medicinal Products for Human Use (EU CHMP) licensure criteria. Two doses of 3.75 μg antigen with 50% of the standard MF59 dose fulfilled these licensure criteria.

A novel mammalian cell-culture technique for consistent production of a well-tolerated and immunogenic trivalent subunit influenza vaccine.

Conventional influenza vaccine production methods have limitations due to their reliance on chicken eggs. We evaluated whether a mammalian cell-culture system could reliably produce an influenza vaccine with favourable tolerability and immunogenicity profiles. Adult subjects (n=1200; 18-60 years of age) were randomized (2:2:2:1) to receive either one of three lots of a cell-culture-derived influenza vaccine (CCIV) or an egg-based trivalent inactivated influenza vaccine (TIV). Safety and reactogenicity were assessed using solicited indicators for 7 days post-vaccination, all other adverse events (AEs) were recorded for 21 days post-vaccination, and all serious AEs and AEs necessitating a physicians visit, and/or resulting in subjects withdrawal from the study, were collected for up to 6 months post-vaccination. Antibody titres were measured by haemagglutination inhibition (HI) assay using egg-based viral antigens. All three lots of CCIV had similar safety and tolerability profiles, analogous to those of the TIV. Lot-to-lot consistency was statistically demonstrated through bioequivalence for immunogenicity. Antibody titres assessed at 6 months demonstrated good persistence. This Phase III trial is the first to demonstrate lot-to-lot bioequivalence of a CCIV and persistence of immunogenicity in comparison with a TIV.

Assessment of the immunogenicity and safety of varying doses of an MF59®-adjuvanted cell culture-derived A/H1N1 pandemic influenza vaccine in Japanese paediatric, adult and elderly subjects

INTRODUCTION Effective vaccination strategies are required to combat future influenza pandemics. Here we report the results of three independent clinical trials performed in Japan to assess the immunogenicity, tolerability and safety of varying doses of a cell culture-derived MF59(®)-adjuvanted A/H1N1 pandemic vaccine in healthy Japanese paediatric, adult and elderly subjects. METHODS One hundred and twenty-three children (6 months-18 years), and 200 adults (19-60 years) were randomly assigned in a 1:1 ratio to receive two doses of vaccine containing either 7.5 μg antigen with a full (9.75 mg) adjuvant dose, or 3.75 μg antigen with a half (4.875 mg) adjuvant dose. One hundred elderly (≥ 61 years) subjects received only the low antigen/adjuvant vaccine formulation. Immunogenicity was assessed by haemagglutination inhibition assay at baseline and three weeks after the first and second vaccine doses on Days 22 and 43, respectively. Solicited and unsolicited adverse reactions were recorded for seven and 21 days post-immunization, respectively. RESULTS In adult and elderly subjects, a single low antigen/adjuvant dose vaccination was sufficient to meet all of the three European licensure criteria established for influenza vaccines. One high, or two low antigen/adjuvant dose vaccinations were required to meet the licensure criteria in paediatric subjects. Both vaccine formulations were well tolerated, with the majority of adverse reactions mild to moderate in severity. None of the five serious adverse events reported throughout the three trials were considered to be vaccine-related by the investigators. CONCLUSION The use of MF59 adjuvant allows for much reduced vaccine antigen content, and a single dose administration schedule in adults and the elderly. The production of pandemic vaccine using modern cell culture techniques is highly advantageous in terms of the quantity, quality, and rapidity of antigen production; these benefits, in combination with the use of MF59, maximize manufacturing capacity and global vaccine supply. These data support the suitability of the investigational vaccine for use in the Japanese paediatric, adult, and elderly populations.