Control Strategy Approach for a Well-Characterized Vaccine Drug Product.

Trumenba (MenB-FHbp; bivalent rLP2086), the first meningococcal serogroup B vaccine approved in the United States and subsequently approved in Europe, Canada, and Australia, is well-characterized. Pfizer devised a control strategy approach by using a simplified control strategy wheel for Trumenba based on International Council for Harmonisation (ICH) Q8 (R2), Q9, Q10, and Q11 guidelines, which provide complementary guidance on pharmaceutical development, quality risk management, quality systems, and development and manufacture of drug substances, respectively. These guidelines ensure product quality using a scientific and risk-based approach. Trumenba contains two factor H binding proteins (FHbps), one from each of the two FHbp subfamilies (A and B), adsorbed onto aluminum phosphate. Trumenba manufacturing processes are complicated by the recombinant protein expression of Subfamily A and B proteins and the nature of the drug product (suspension in syringes); the latter also introduces challenges in controlling product critical quality attributes during the development process. In such complex systems, the control strategy is critical to ensuring consistent desired product quality; it also supports the regulatory requirement of continued improvement through continuous process verification and aids regulatory filing. This article describes Pfizer's approach toward robust control strategy development, built on product and process understanding, and links control strategy to regulatory document sections and flow of controls. Specifically, an approach is presented on product quality attribute criticality determination based on safety and efficacy and on an understanding of process parameter criticality. This was achieved by studying the impact of the approach on product quality attributes to define process parameter and in-process controls. This approach is further explained through Trumenba case studies, highlighting specific quality attributes and the associated controls implemented, and provides a holistic view of controls employed for both drug substance and drug product.

Synthesis and immunological study of α-2,9-oligosialic acid conjugates as anti-group C meningitis vaccines.

α-2,9-Di-, tri-, tetra-, and pentasialic acids were prepared and conjugated with a carrier protein. The resultant glycoconjugates elicited robust T cell-mediated immunity in mice. α-2,9-Trisialic acid was identified as a promising antigen for developing glycoconjugate vaccines against group C Neisseria meningitidis.

Determination of hydrazine in a meningococcal C conjugate vaccine intermediary product.

In Brazil, polysaccharide-protein conjugate vaccine against Neisseria meningitidis group C (MenCPS-TT) using hydrazine-activated-tetanus toxoid (TT) as a carrier protein has been developed. Because of the toxicity of hydrazine in humans, it is necessary to monitor this substance's process control step during the vaccine production. The electroanalytical methodology was developed and validated for the determination of hydrazine during the process control of MenCPS-TT vaccine production by differential pulse polarography. The reduction potential was -0.95 V in acetone and sulphuric acid solution. The method presented linear range between 30 and 150 microgL(-1)and recovery of 93.5+/-0.8%.

Investigating the candidacy of LPS-based glycoconjugates to prevent invasive meningococcal disease: chemical strategies to prepare glycoconjugates with good carbohydrate loading.

In previous studies protective antibodies that could facilitate bactericidal killing of Neisseria meningitidis (Nm) serogroup B strains were derived from immunisation with glycoconjugates prepared from O-deacylated lipopolysaccharide (LPS-OH) via direct reductive amination between the reducing end of the oligosaccharide molecule, created by treatment with alkaline phosphatase, and amino functionalities on the CRM(197) carrier protein. These glycoconjugates proved difficult to prepare because the presence of amide linked fatty-acyl groups results in glycolipids that are relatively insoluble and aggregate. Therefore, we have examined several strategies to prepare glycoconjugates in order to identify a robust, consistently reproducible strategy that produces glycoconjugates with a high loading of LPS derived oligosaccharides. Initially we used completely deacylated LPS molecules, but lacking phosphoethanolamine (PEtn) from the core OS as the strong basic conditions required to completely deacylate the LPS would modify the PEtn residue. We utilised a squarate linker and conjugated via the reducing end of the carbohydrate antigen following removal of the glycosidic phosphate to amino groups on CRM(197), however carbohydrate loading on the carrier protein was low. Glycoconjugates were then produced utilising amidases produced by Dictyostelium discoideum (Dd), which partially remove N-linked fatty acids from the lipid A region of the Nm LPS molecule, which enabled the retention of the PEtn residue. LPS-OH was treated with Dd amidase, the reducing glycosidic phosphate removed, and using a cystamine linker strategy, conjugated to the carrier protein. Carbohydrate loading was somewhat improved but still not high. Finally, we have developed a novel conjugation strategy that targets the amino functionality created by the amidase activity as the attachment point. The amino functionality on the PEtn residue of the inner core was protected via a novel blocking and unblocking strategy with t-butyl oxycarbonyl. A maleimide-thiol linker strategy, targeting lysine residues on the carrier protein did not result in high loading of the carbohydrate molecules, however when we targeted the carboxyl residues we have consistently obtained a high loading of carbohydrate antigens per CRM(197), which can be controlled by variation in the amount of activated carbohydrate utilised in the conjugation reaction.

The implications of vaccines for prevention of bacterial meningitis.

PURPOSE OF REVIEW: Conjugate vaccines now exist that can protect against some types of bacterial meningitis (Haemophilus influenzae type b, Neisseria meningitidis group C and seven serotypes of Streptococcus pneumoniae). To broaden the protection against meningitis, new vaccines are needed. This article reviews new uses of the established vaccines and the new meningitis vaccines in development. RECENT FINDINGS: A conjugate group A meningococcal vaccine to prevent epidemics of meningitis in Africa is about to be used widely in the 'meningitis belt'. A 'quadrivalent' conjugate vaccine against meningococcal serogroups A C Y and W135 is in use in the United States. A 'tailor-made' group B meningococcal vaccine was successfully used to control an epidemic of meningococcal disease in New Zealand. Other group B meningococcal vaccines are in development. Despite routine vaccination against pneumococcus in the United States, this organism is still the commonest cause of meningitis. Pneumococcal vaccines need to include more serotypes to offer broader protection. SUMMARY: Great progress has been made in developing vaccines that prevent meningitis. The remaining challenges are to introduce vaccines with broad protection against meningococci and pneumococcus, develop an effective vaccine against group B meningococcus and to get these highly effective vaccines to those areas of the world that most need them.

Vaccines containing de-N-acetyl sialic acid elicit antibodies protective against neisseria meningitidis groups B and C.

Murine mAbs that were produced by immunization with a vaccine containing the N-propionyl derivative of Neisseria meningitidis group B (MenB) capsular polysaccharide (NPr MBPS) mediate protective responses against MenB but were not reactive with unmodified MBPS or chemically identical human polysialic acid (PSA). Recently, we showed that some of the mAbs were reactive with MBPS derivatives that contain de-N-acetyl sialic acid residues. In this study we evaluated the immunogenicity of de-N-acetyl sialic acid-containing derivatives of PSA (de-N-acetyl PSA) in mice. Four de-N-acetyl PSA Ags were prepared and conjugated to tetanus toxoid, including completely de-N-acetylated PSA. All of the vaccines elicited anti-de-N-acetyl PSA responses (titers >/=1/10,000), but only vaccines enriched for nonreducing end de-N-acetyl residues by treatment with exoneuraminidase or complete de-N-acetylation elicited high titers against the homologous Ag. Also, nonreducing end de-N-acetyl residue-enriched vaccines elicited IgM and IgG Abs of all subclasses that could bind to MenB. The results suggest that the zwitterionic characteristic of neuraminic acid, particularly at the nonreducing end, may be important for processing and presentation mechanisms that stimulate T cells. Abs elicited by all four vaccines were able to activate deposition of human complement proteins and passively protect against challenge by MenB in the infant rat model of meningococcal bacteremia. Some vaccine antisera mediated bactericidal activity against a N. meningitidis group C strain with human complement. Thus, de-N-acetyl PSA Ags are immunogenic and elicit Abs that can be protective against MenB and N. meningitidis group C strains.

[Synthesis and biological properties of polysaccharide-peptide conjugates as potential antigens for a vaccine against meningococci of serogroups A and B].

A new approach to the development of a vaccine against meningococci of serogroups A and B was proposed. It involves the synthesis of conjugates of high-molecular capsule polysaccharides of the serogroup A meningococcus (PsA) with earlier synthesized protective fragments of membrane proteins from serogroup B meningococci. The conjugates were synthesized using a method that consists of the generation of aldehyde groups by oxidizing free vicinal hydroxyl groups of PsA and subsequent reaction of these groups with amino groups of the peptide. The reaction proceeds with the intermediate formation of the Schiff base, which is reduced to the stable secondary amine. The main parameters of the reaction were optimized in the synthesis of a PsA conjugate with a model peptide and methods of their characterization were developed. The reproducibility and efficiency of the synthetic procedure were demonstrated by the example of synthesis of PsA conjugates with fragments of protein PorA from the outer membrane of the serogroup B meningococcus. It was shown that, when administered without adjuvant, a conjugate of PsA with a protective peptide, which represents an exposed conserved fragment 306-332 of protein PorA, stimulates the formation of antibodies to the peptide and polysaccharide moieties of the molecule and is also capable of decreasing the degree of bacteremia in animals infected with serogroup A and serogroup B meningococci. The approach can be applied to the development of a complex vaccine for serogroup A and serogroup B meningococci.

Conjugates of group A and W135 capsular polysaccharides of neisseria meningitidis bound to recombinant Staphylococcus aureus enterotoxin C1: preparation, physicochemical characterization, and immunological properties in mice.

Neisseria meningitidis groups A (GAM) and W135 capsular polysaccharides (CPs) were bound to recombinant Staphylococcus aureus enterotoxin C1 (rSEC). The CPs were activated with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate and then bound to adipic acid dihydrazide derivatives of rSEC. Syntheses were conducted with native GAM CP (GAMP), W135 CP (W135P), and ultrasonicated or hydrazine-treated W135P at various concentrations of reactants, pHs, and ionic strengths. The conjugates were characterized by compositional and serologic analyses, high-performance size-exclusion chromatography with multi-angle laser light scattering detection, and immunogenicity in 5- to 6-week-old mice. Conjugates injected subcutaneously in phosphate-buffered saline elicited immunoglobulin G (IgG) responses against their respective CPs and rSEC, whereas GAMP and W135P alone did not induce detectable CP antibodies. The O-acetyl content of W135P was low, and its removal had no adverse effect upon the conjugate's immunogenicity. Reduction of the molecular size of W135P by treatment with hydrazine improved the immunogenicity of W135P-rSEC. IgG anti-CP elicited by the conjugates showed complement-dependent bactericidal activity against their respective organisms, and IgG anti-rSEC neutralized the T-cell proliferative activity of native SEC. A bivalent formulation of GAMP-rSEC and W135P-rSEC elicited IgG anti-CP at comparable levels to those induced by the conjugates administered separately.

Recent developments in Neisseria meningitidis group A conjugate vaccines.

Meningococcal disease, both endemic and epidemic, remains a major cause of meningitis in many countries. Protective immunity is mediated primarily by bacteriocidal antibodies against the capsular polysaccharides for serogroups other than B, and against non-capsular surface components for group B. This article focuses on the development of conjugate vaccines for serogroup A, with special emphasis on the needs of Africa. The first licensed (1999) meningococcal conjugate was against group C in the UK and was > 90% effective in infants, children and young adults. The problem now is to develop a highly immunogenic group A meningococcal conjugate vaccine for use in developing countries as an alternative to the presently licensed group AC polysaccharide vaccine. Immunogenicity studies on the group A polysaccharide show the polysaccharide itself to be uniquely immunogenic in young children compared with other polysaccharides, making comparative studies with a highly immunogenic conjugate of considerable importance.

Phase I study of detoxified Escherichia coli J5 lipopolysaccharide (J5dLPS)/group B meningococcal outer membrane protein (OMP) complex vaccine in human subjects.

We previously observed that a detoxified Escherichia coli O111, Rc chemotype J5 lipopolysaccharide (J5dLPS)/group B meningococcal outer membrane protein (OMP) vaccine protected animals from experimental lethal sepsis when immune antibodies were given passively as treatment at the onset of fever or when vaccine was given actively as prophylaxis. To test the safety and immunogenicity of this vaccine, we administered doses of 5, 10 and 25 microg (based on dLPS) of vaccine at days 0, 28 and 56 to 24 human subjects (8 per group). Temperatures of 100.3, 99.5 and 99.4 degrees F occurred in three subjects. At 24h, pain at the injection site was moderate in 38%, mild in 44% and not present in 18%, while at 48 h, it was 1, 25 and 73%, respectively. No alterations in baseline renal, hepatic or hematologic functions occurred. There were two to three times mean-fold increases in anti-J5dLPS IgG (range: 1.9-5.1) and IgM (range: 1.2-9.2) levels in subjects receiving the 10 and 25 microg doses. At 12-month follow-up, three of the original responders had continued elevation of antibody levels. A 25 microg booster dose of vaccine did not increase antibody levels among those responders and did not elicit antibodies among three subjects with no previous antibody response. The plasma from the six volunteers inhibited LPS-induced cytokine generation in human whole blood ex vivo. We conclude that this J5dLPS/OMP vaccine was safe and well-tolerated with transient, local pain at the injection site. Vaccine formulations with different adjuvants are currently under investigation.