A randomized trial to assess safety and immunogenicity of alternative formulations of a quadrivalent meningococcal (A, C, Y, and W-135) tetanus protein conjugate vaccine in toddlers

Quadrivalent meningococcal tetanus toxoid-conjugate booster vaccination in adolescents and adults: phase III randomized study

BACKGROUND

The immunogenicity and safety of a booster dose of tetanus toxoid-conjugate quadrivalent meningococcal vaccine (MenACYW-TT), alone or co-administered with MenB vaccine, were assessed in healthy 13-25-year olds who received MenACYW-TT or a CRM-conjugate vaccine (MCV4-CRM) 3-6 years earlier.

METHODS

This phase IIIb open-label trial (NCT04084769) evaluated MenACYW-TT-primed participants, randomized to receive MenACYW-TT alone or with a MenB vaccine, and MCV4-CRM-primed participants who received MenACYW-TT alone. Functional antibodies against serogroups A, C, W and Y were measured using human complement serum bactericidal antibody assay (hSBA). The primary endpoint was vaccine seroresponse (post-vaccination titers ≥1:16 if pre-vaccination titers <1:8; or a ≥4-fold increase if pre-vaccination titers ≥1:8) 30 days post booster. Safety was evaluated throughout the study.

RESULTS

The persistence of the immune response following primary vaccination with MenACYW-TT was demonstrated. Seroresponse after MenACYW-TT booster was high regardless of priming vaccine (serogroup A: 94.8% vs 93.2%; C: 97.1% vs 98.9%; W: 97.7% vs 98.9%; and Y; 98.9% vs 100% for MenACWY-TT-primed and MCV4-CRM-primed groups, respectively). Co-administration with MenB vaccines did not affect MenACWY-TT immunogenicity. No vaccine-related serious adverse events were reported.

CONCLUSIONS

MenACYW-TT booster induced robust immunogenicity against all serogroups, regardless of the primary vaccine received, and had an acceptable safety profile.

IMPACT

A booster dose of MenACYW-TT induces robust immune responses in children and adolescents primed with MenACYW-TT or another MCV4 (MCV4-DT or MCV4-CRM), respectively. Here, we demonstrate that MenACYW-TT booster 3-6 years after primary vaccination induced robust immunogenicity against all serogroups, regardless of the priming vaccine (MenACWY-TT or MCV4-CRM), and was well tolerated. Persistence of the immune response following previous primary vaccination with MenACYW-TT was demonstrated. MenACYW-TT booster with MenB vaccine co-administration did not affect MenACWY-TT immunogenicity and was well tolerated. These findings will facilitate the provision of broader protection against IMD particularly in higher-risk groups such as adolescents.

Different Long-Term Duration of Seroprotection against Neisseria meningitidis in Adolescents and Middle-Aged Adults after a Single Meningococcal ACWY Conjugate Vaccination in The Netherlands

Neisseria meningitidis is often asymptomatically carried in the nasopharynx but may cause invasive meningococcal disease, leading to morbidity and mortality. Meningococcal conjugate vaccinations induce functional protective antibodies against capsular antigens, but seroprotection wanes over time. We measured functional antibody titers five years after administration of a single dose of the meningococcal ACWY-polysaccharide-specific tetanus toxoid-conjugated (MenACWY-TT) vaccine in adolescents and middle-aged adults in the Netherlands, using the serum bactericidal antibody with baby rabbit complement (rSBA) assay. Protection was defined as rSBA titer ≥8. The meningococcal ACWY-specific serum IgG concentrations were measured with a multiplex immunoassay. Duration of protection was estimated by a bi-exponential decay model. Sufficient protection for MenC, MenW, and MenY was achieved in 94–96% of the adolescents five years postvaccination, but, in middle-aged adults, only in 32% for MenC, 65% for MenW and 71% for MenY. Median duration of protection for MenCWY was 4, 14, and 21 years, respectively, in middle-aged adults, while, in adolescents, it was 32, 98, and 33 years. Our findings suggest that adolescents, primed in early childhood with MenC conjugate vaccination, remain sufficiently protected after a single dose of MenACWY-TT vaccine. Middle-aged adults without priming vaccination show fast waning of antibodies, particularly MenC, for which protection is lost after four years.

Immunogenicity and safety of meningococcal group A, C, W and Y tetanus toxoid conjugate vaccine: review of clinical and real-world evidence

Protection by meningococcal group A, C, W and Y (MenACWY) vaccines against four meningococcal disease-causing serogroups is increasingly important because of changing epidemiologic patterns of meningococcal disease, including recent meningococcal serogroup W outbreaks/disease clusters. The MenACWY vaccine conjugated to tetanus toxoid (MenACWY-TT) has been extensively evaluated across the age spectrum (age ≥6 weeks) in randomized Phase II and III and in postmarketing studies. Results support the robust immunogenicity of MenACWY-TT across ages and coadministration with other vaccines. The safety profile is similar regardless of age, primary versus booster vaccination, or concomitant administration; local (swelling, pain, redness) and systemic (fever, fatigue, headache, drowsiness, loss of appetite, irritability) reactogenicity events are most common. These data support use of MenACWY-TT to protect against MenACWY disease.

Potential targets for next generation antimicrobial glycoconjugate vaccines

Cell surface carbohydrates have been proven optimal targets for vaccine development. Conjugation of polysaccharides to a carrier protein triggers a T-cell-dependent immune response to the glycan moiety. Licensed glycoconjugate vaccines are produced by chemical conjugation of capsular polysaccharides to prevent meningitis caused by meningococcus, pneumococcus and Haemophilus influenzae type b. However, other classes of carbohydrates (O-antigens, exopolysaccharides, wall/teichoic acids) represent attractive targets for developing vaccines. Recent analysis from WHO/CHO underpins alarming concern toward antibiotic-resistant bacteria, such as the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) and additional pathogens such as Clostridium difficile and Group A Streptococcus. Fungal infections are also becoming increasingly invasive for immunocompromised patients or hospitalized individuals. Other emergencies could derive from bacteria which spread during environmental calamities (Vibrio cholerae) or with potential as bioterrorism weapons (Burkholderia pseudomallei and mallei, Francisella tularensis). Vaccination could aid reducing the use of broad-spectrum antibiotics and provide protection by herd immunity also to individuals who are not vaccinated.

This review analyzes structural and functional differences of the polysaccharides exposed on the surface of emerging pathogenic bacteria, combined with medical need and technological feasibility of corresponding glycoconjugate vaccines.

Factors contributing to the immunogenicity of meningococcal conjugate vaccines

Various glycoprotein conjugate vaccines have been developed for the prevention of invasive meningococcal disease, having significant advantages over pure polysaccharide vaccines. One of the most important features of the conjugate vaccines is the induction of a T-cell dependent immune response, which enables both the induction of immune memory and a booster response after repeated immunization. The nature of the carrier protein to which the polysaccharides are chemically linked, is often regarded as the main component of the vaccine in determining its immunogenicity. However, other factors can have a significant impact on the vaccine's profile. In this review, we explore the physico-chemical properties of meningococcal conjugate vaccines, which can significantly contribute to the vaccine's immunogenicity. We demonstrate that the carrier is not the sole determining factor of the vaccine's profile, but, moreover, that the conjugate vaccine's immunogenicity is the result of multiple physico-chemical structures and characteristics.

A multi-criteria decision making approach to identify a vaccine formulation

This article illustrates the use of a multi-criteria decision making approach, based on desirability functions, to identify an appropriate adjuvant composition for an influenza vaccine to be used in elderly. The proposed adjuvant system contained two main elements: monophosphoryl lipid and α-tocopherol with squalene in an oil/water emulsion. The objective was to elicit a stronger immune response while maintaining an acceptable reactogenicity and safety profile. The study design, the statistical models, the choice of the desirability functions, the computation of the overall desirability index, and the assessment of the robustness of the ranking are all detailed in this manuscript.

Meningococcal serogroups A, C, W-135, and Y tetanus toxoid conjugate vaccine: a new conjugate vaccine against invasive meningococcal disease

Invasive meningococcal disease is a serious infection that occurs worldwide. It is caused by Neisseria meningitidis, of which six serogroups (A, B, C, W-135, X, and Y) are responsible for most infections. The case fatality rate of meningococcal disease remains high and can lead to significant sequelae. Vaccination remains the best strategy to prevent meningococcal disease. Polysaccharide vaccines were initially introduced in the late 1960s but their limitations (poor immunogenicity in infants and toddlers and hyporesponsiveness after repeated doses) have led to the development and use of meningococcal conjugate vaccines, which overcome these limitations. Two quadrivalent conjugated meningococcal vaccines – MenACWY-DT (Menactra^®) and MenACWY-CRM₁₉₇ (Menveo^®) – using diphtheria toxoid or a mutant protein, respectively, as carrier proteins have already been licensed in the US. Recently, a quadrivalent meningococcal vaccine conjugated to tetanus toxoid (MenACWY-TT; Nimenrix^®) was approved for use in Europe in 2012. The immunogenicity of MenACWY-TT, its reactogenicity and safety profile, as well as its coadministration with other vaccines are discussed in this review. Clinical trials showed that MenACWY-TT was immunogenic in children above the age of 12 months, adolescents, and adults, and has an acceptable reactogenicity and safety profile. Its coadministration with several other vaccines that are commonly used in children, adolescents, and adults did not affect the immunogenicity of MenACWY-TT or the coadministered vaccine, nor did it affect its reactogenicity and safety. Other studies are now ongoing in order to determine the immunogenicity, reactogenicity, and safety of MenACWY-TT in infants from the age of 6 weeks.

Protein carriers of conjugate vaccines: characteristics, development, and clinical trials

The immunogenicity of polysaccharides as human vaccines was enhanced by coupling to protein carriers. Conjugation transformed the T cell-independent polysaccharide vaccines of the past to T cell-dependent antigenic vaccines that were much more immunogenic and launched a renaissance in vaccinology. This review discusses the conjugate vaccines for prevention of infections caused by Hemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis. Specifically, the characteristics of the proteins used in the construction of the vaccines including CRM, tetanus toxoid, diphtheria toxoid, Neisseria meningitidis outer membrane complex, and Hemophilus influenzae protein D are discussed. The studies that established differences among and key features of conjugate vaccines including immunologic memory induction, reduction of nasopharyngeal colonization and herd immunity, and antibody avidity and avidity maturation are presented. Studies of dose, schedule, response to boosters, of single protein carriers with single and multiple polysaccharides, of multiple protein carriers with multiple polysaccharides and conjugate vaccines administered concurrently with other vaccines are discussed along with undesirable consequences of conjugate vaccines. The clear benefits of conjugate vaccines in improving the protective responses of the immature immune systems of young infants and the senescent immune systems of the elderly have been made clear and opened the way to development of additional vaccines using this technology for future vaccine products.

Prevention of meningococcal infections in the first 2 years of life

The spectrum of disease caused by Neisseria meningitidis includes bacteremia, fulminant sepsis (meningococcemia), meningitis, and pneumonia. The incidence of meningococcal infection has long been higher in infancy than adolescents or adults older than 65 years (a third group with an increased risk based on age). Five meningococcal serogroups (A, B, C, Y, and W135) cause the great majority of human disease. Serogroup B strains cause about two-thirds of disease in children younger than 6 years. For this reason, new meningococcal vaccine formulations have been developed and evaluated in children younger than 2 years. Of four meningococcal vaccines currently licensed in the United States, two conjugate products, (MenACWY-D [Menactra], Sanofi Pasteur; HibMenCY-TT [MenHibrix], GlaxoSmithKline), are recommended for infants and toddlers younger than 2 years who have an increased risk for invasive meningococcal disease. High-risk conditions are complement deficiencies, community outbreaks, functional or anatomic asplenia, and travel to high-risk areas in which serogroup A infection is prevalent. Recommendations vary by age, dosing, and indication between these two products. Both licensed products are immunogenic and have side-effect profiles that are considered safe for use. In most cases, concomitant use with other recommended childhood vaccines does not interfere with responses to these vaccines. As of yet, there has not been universal adoption of this immunization in the infant population by parents or providers. Factors that weigh against the implementation of a national routine infant program include the prevention of only 40 to 50 meningococcal cases, two to four deaths per year, and a relatively low case fatality among infants. Some argue that costs should not be considered a barrier because infant deaths and morbidity would be prevented. The availability of a serogroup B vaccine would improve impact and cost-effectiveness of a routine infant meningococcal vaccine program. Debate over the implementation of routine infant meningococcal vaccination in the United States is ongoing. This review focuses on vaccines for the prevention of N. meningitidis infection in infants and young toddlers in the first 2 years of life.

Meningococcal quadrivalent (serogroups A, C, W135 and Y) tetanus toxoid conjugate vaccine (Nimenrix™)

Nimenrix™ (MenACWY-TT) is a quadrivalent meningococcal conjugate vaccine, comprising the polysaccharide serogroups A, C, W135 and Y, and tetanus toxoid (TT) as carrier protein. It is the first quadrivalent vaccine (administered as a single dose) to be approved in Europe for active immunization of individuals aged ≥ 12 months against invasive meningococcal disease caused by Neisseria meningitidis serogroups A, C, W135 and Y. Administration of a single dose of Nimenrix™ elicited a strong immune response against all four vaccine serogroups in healthy toddlers aged 12-23 months, children and adolescents aged 2-17 years and adults aged 18-55 years in randomized, multicentre, phase III trials. In toddlers, Nimenrix™ was noninferior to Meningitec® in terms of seroresponse rates against meningococcal serogroup C 42 days post-vaccination. In children, adolescents and adults, Nimenrix™ was noninferior to Mencevax™ in terms of vaccination response rates against all four serogroups 1 month post-vaccination. Furthermore, several phase II studies and a phase III trial showed that the immune response elicited by Nimenrix™ in all age groups persisted for 7-42 months after the primary vaccination (when evaluated by rabbit serum bactericidal activity), with the vaccine also inducing immune memory in toddlers. In addition, several randomized, multicentre, phase III, noninferiority trials showed that when coadministered with other childhood vaccines or a seasonal flu vaccine, the immunogenicity of Nimenrix™ or that of the coadministered vaccine was generally not altered. Nimenrix® was generally well tolerated in all age groups whether administered as a single vaccine or coadministered with other routine vaccines. The incidence of grade 3 local or systemic solicited adverse events during the first 4 days following vaccination and of serious adverse events over an extended follow-up period of up to 6 months was low (<4.5%). Although protective effectiveness and longer-term persistence studies are required, current evidence suggests that Nimenrix™, administered as a single dose, provides a valuable vaccination option for the prevention of meningococcal disease across a broad age group, including children as young as 12 months.

Neisseria lactamica antigens complexed with a novel cationic adjuvant

Colonization of the nasopharynx by non-pathogenic Neisseria species, including N. lactamica, has been suggested to lead to the acquisition of natural immunity against Neisseria meningitidis in young children. The aim of this study was to identify a model complex of antigens and adjuvant for immunological preparation against N. meningitidis B, based on cross reactivity with N. lactamica outer membrane vesicles (OMV) antigens and the (DDA-BF) adjuvant. Complexes of 25 µg of OMV in 0.1 mM of DDA-BF were colloidally stable, exhibiting a mean diameter and charge optimal for antigen presentation. Immunogenicity tests for these complexes were performed in mice. A single dose of OMV/DDA-BF was sufficient to induce a (DTH) response, while the same result was achieved only after two doses of OMV/alum. In addition, to achieve total IgG levels that are similar to a single immunization with OMV/DDA-BF, it was necessary to give the mice a second dose of OMV/alum. Moreover, the antibodies induced from a single immunization with OMV/DDA-BF had an intermediate avidity, but antibodies with a similar avidity were only induced by OMV/alum after two immunizations. The use of this novel cationic adjuvant for the first time with a N. lactamica OMV preparation revealed good potential for future vaccine design.