Intranasal M2SR (M2-Deficient Single Replication) H3N2 Influenza Vaccine Provides Enhanced Mucosal and Serum Antibodies in Adults.

BACKGROUND: We previously demonstrated that an intranasal dose of 108 50% tissue culture infectious dose (TCID50) M2-deficient single replication (M2SR) influenza vaccine protected against highly drifted H3N2 influenza challenge in a subset of subjects who demonstrated ≥2-fold increase in microneutralization (MN) antibodies to Belgium2015 (the challenge strain) after vaccination. Here, we describe a phase 1b, observer-blinded, dose-escalation study demonstrating an increased proportion of responders with this signal of immune protection. METHODS: Serosusceptible subjects aged 18-49 years were randomized to receive 2 doses (108-109 TCID50) of M2SR or placebo administered 28 days apart. Clinical specimens were collected before and after each dose. The primary objective was to demonstrate safety of M2SR vaccines. RESULTS: The vaccine was well tolerated at all dose levels. Against Belgium2015, ≥ 2-fold increases in MN antibodies were noted among 40% (95% confidence interval [CI], 24.9%-56.7%) of subjects following a single 108 TCID50 M2SR dose and among 80.6% (95% CI, 61.4%-92.3%) after 109 dose (P < .001). A single 109 TCID50 dose of M2SR generated ≥4-fold hemagglutination inhibition antibody seroconversion against the vaccine strain in 71% (95% CI, 52.0%-85.8%) of recipients. Mucosal and cellular immune responses were also induced. CONCLUSIONS: These results indicate that M2SR may provide substantial protection against infection with highly drifted strains of H3N2 influenza. CLINICAL TRIALS REGISTRATION: NCT03999554.

In recent years, influenza A H3N2 viruses have evolved into multiple cocirculating clades, resulting in low vaccine efficacy and highlighting the need for more effective influenza vaccines. In a previous challenge study, a single intranasal dose of the investigational vaccine M2SR demonstrated protection against a highly drifted H3N2 influenza challenge virus in a subset of vaccine recipients with a signature immune response. Increasing the dose of the M2SR vaccine in this phase1b study demonstrated a statistically significant increase in the proportion of subjects with the signature immune responses seen previously. The vaccine-induced antibodies were cross-reactive with a panel of drifted H3N2 viruses from 2007 to 2019. Additionally, M2SR generated a rise in serum hemagglutination inhibition antibody titer in 71% of subjects. In contrast, the H3N2 seroresponse rate for the licensed intranasal vaccine FluMist is 10% in seronegative adults. Moreover, M2SR elicited mucosal and cell-mediated immune responses. This study demonstrates that the intranasal M2SR generates a multifaceted immune response and has the potential to provide better efficacy against vaccine-matched strains and influenza drift variants reducing the need to update the vaccine on an annual basis. This is a noteworthy step in the development of a broadly protective influenza vaccine.

Safety data from the MenB-FHbp clinical development program in healthy individuals aged 10 years and older.

BACKGROUND: The MenB-FHbp vaccine (Trumenba®) is licensed in various countries for the prevention of meningococcal serogroup B disease in individuals ≥ 10 years of age. The clinical development program included 11 completed trials where, in each trial, MenB-FHbp had an acceptable safety profile after a primary vaccination series was administered to individuals 10-65 years of age. However, the detection of potential rare events was limited because of individual clinical trial size. The current safety analysis evaluates pooled reactogenicity and other adverse events (AEs) reported in these trials to identify new safety signals not detectable in individual trials. METHODS: Eleven trials contributed safety data, of which 10 recorded local and systemic reactogenicity events; 8 of the trials were controlled, and reactogenicity data were pooled for 7 of these 8 trials. Additional AE evaluations included immediate AEs (IAEs), medically attended AEs (MAEs), serious AEs (SAEs), newly diagnosed chronic medical conditions (NDCMCs), and autoimmune or neuroinflammatory conditions. RESULTS: Local and systemic reactions were more frequent in the MenB-FHbp group (n = 15,294) compared with controls (n = 5509), although most reactions were transient and mild to moderate in severity. Frequencies of IAEs, SAEs, MAEs, NDCMCs, and autoimmune or neuroinflammatory conditions were similar between the MenB-FHbp and control groups. CONCLUSIONS: MenB-FHbp demonstrated a favorable safety and tolerability profile in the clinical development program of > 15,000 vaccine recipients ≥ 10 years of age. No new safety signals were identified in the pooled analysis compared with data from the individual trials. Continued postmarketing safety surveillance is important for the identification of rare events. Clinicaltrials.gov: NCT01299480; NCT000808028; NCT00879814; NCT00780806; NCT01352845; NCT01352793; NCT01461993; NCT01323270; NCT01830855; NCT01461980; NCT01768117.

M2-Deficient Single-Replication Influenza Vaccine-Induced Immune Responses Associated With Protection Against Human Challenge With Highly Drifted H3N2 Influenza Strain.

BACKGROUND: Current influenza vaccines are strain specific and demonstrate low vaccine efficacy against H3N2 influenza disease, especially when vaccine is mismatched to circulating virus. The novel influenza vaccine candidate, M2-deficient single replication (M2SR), induces a broad, multi-effector immune response. METHODS: A phase 2 challenge study was conducted to assess the efficacy of an M2SR vaccine expressing hemagglutinin and neuraminidase from A/Brisbane/10/2007 (Bris2007 M2SR H3N2; clade 1). Four weeks after vaccination, recipients were challenged with antigenically distinct H3N2 virus (A/Belgium/4217/2015, clade 3C.3b) and assessed for infection and clinical symptoms. RESULTS: Adverse events after vaccination were mild and similar in frequency for placebo and M2SR recipients. A single dose of Bris2007 M2SR induced neutralizing antibody to the vaccine (48% of recipients) and challenge strain (27% of recipients). Overall, 54% of M2SR recipients were infected after challenge, compared with 71% of placebo recipients. The subset of M2SR recipients with a vaccine-induced microneutralization response against the challenge virus had reduced rates of infection after challenge (38% vs 71% of placebo recipients; P = .050) and reduced illness. CONCLUSIONS: Study participants with vaccine-induced neutralizing antibodies were protected against infection and illness after challenge with an antigenically distinct virus. This is the first demonstration of vaccine-induced protection against a highly drifted H3N2 challenge virus.

Safety and Immunogenicity of M2-Deficient, Single Replication, Live Influenza Vaccine (M2SR) in Adults.

M2SR (M2-deficient single replication) is an investigational live intranasal vaccine that protects against multiple influenza A subtypes in influenza-naïve and previously infected ferrets. We conducted a phase 1, first-in-human, randomized, dose-escalation, placebo-controlled study of M2SR safety and immunogenicity. Adult subjects received a single intranasal administration with either placebo or one of three M2SR dose levels (106, 107 or 108 tissue culture infectious dose (TCID50)) expressing hemagglutinin and neuraminidase from A/Brisbane/10/2007 (H3N2) (24 subjects per group). Subjects were evaluated for virus replication, local and systemic reactions, adverse events (AE), and immune responses post-vaccination. Infectious virus was not detected in nasal swabs from vaccinated subjects. At least one AE (most commonly mild nasal rhinorrhea/congestion) was reported among 29%, 58%, and 83% of M2SR subjects administered a low, medium or high dose, respectively, and among 46% of placebo subjects. No subject had fever or a severe reaction to the vaccine. Influenza-specific serum and mucosal antibody responses and B- and T-cell responses were significantly more frequent among vaccinated subjects vs. placebo recipients. The M2SR vaccine was safe and well tolerated and generated dose-dependent durable serum antibody responses against diverse H3N2 influenza strains. M2SR demonstrated a multi-faceted immune response in seronegative and seropositive subjects.

MenB-FHbp Vaccine Protects Against Diverse Meningococcal Strains in Adolescents and Young Adults: Post Hoc Analysis of Two Phase 3 Studies.

INTRODUCTION: Two phase 3 studies in adolescents and young adults demonstrated that MenB-FHbp, a meningococcal serogroup B (MenB) vaccine, elicits protective immune responses after 2 or 3 doses based on serum bactericidal antibody assays using human complement (hSBA) against 4 primary and 10 additional diverse, vaccine-heterologous MenB test strains. Lower limits of quantitation (LLOQs; titers 1:8 or 1:16; titers ≥ 1:4 correlate with protection) were used to evaluate responses to individual strains and all 4 primary strains combined (composite response). A post hoc analysis evaluated percentages of subjects with protective responses to as many as 8 strains combined (4 primary plus additional strains). METHODS: Immune responses were measured using hSBAs against 4 primary strains in adolescents (n = 1509, MenB-FHbp; n = 898, hepatitis A virus vaccine/saline) and young adults (n = 2480, MenB-FHbp; n = 824, saline) receiving MenB-FHbp or control at 0, 2, and 6 months. Ten additional strains were evaluated in subsets of subjects from approximately 1800 MenB-FHbp recipients across both studies. Percentages of subjects with hSBA titers ≥ LLOQ for different numbers of primary strains or primary plus additional strains combined (7 or 8 strains total per subset) were determined before vaccination, 1 month post-dose 2, and 1 month post-dose 3. RESULTS: Across the panel of primary plus additional strains, at 1 month post-dose 3, titers ≥ LLOQ were elicited in 93.7-95.7% of adolescents and 91.7-95.0% of young adults for ≥ 5 test strains combined and in 70.5-85.8% of adolescents and 67.5-81.4% of young adults for ≥ 7 strains combined. Among adolescents, 99.8%, 99.0%, 92.8%, and 82.7% had titers ≥ LLOQ against at least 1, 2, 3, and all 4 primary strains, respectively; corresponding percentages for young adults were 99.7%, 97.7%, 94.0%, and 84.5%. CONCLUSIONS: Results support the ability of MenB-FHbp to provide broad coverage against MenB strains expressing diverse FHbp variants. TRIAL REGISTRATION: ClinicalTrials.gov identifiers NCT01830855, NCT01352845.

Sex, Age, and Race Effects on Immunogenicity of MenB-FHbp, A Bivalent Meningococcal B Vaccine: Pooled Evaluation of Clinical Trial Data.

INTRODUCTION: An extensive clinical development program showed that the meningococcal serogroup B-factor H binding protein (MenB-FHbp) vaccine affords protection against MenB disease for adolescents and adults. Data were pooled from multiple studies within the program to examine whether MenB-FHbp immunogenicity was influenced by sex, age, or race. METHODS: Immunogenicity was assessed in subjects from seven studies who received 120 µg MenB-FHbp (at 0, 2, 6 months) and had evaluated immune responses against four representative test strains via serum bactericidal assays using human complement (hSBAs). Immune responses were presented by sex (male, female), age group (10-14, 15-18, 19-25, 10-25 years), and race (white, black, Asian, other). RESULTS: Among 8026 subjects aged 10-25 years included in this analysis, MenB-FHbp elicited robust immune responses in a high percentage of subjects regardless of demographic characteristics. Across all test strains and demographic subsets, a ≥ 4-fold rise in titer from baseline was achieved in 76.7-95.0% of subjects, with no major differences by sex, age groups assessed, or races evaluated. Corresponding percentages achieving titers ≥ the lower limit of quantification (LLOQ) against all four strains combined were 79.7-87.3% (sex), 81.6-85.5% (age), and 80.0-88.1% (race). Minor differences were observed for geometric mean titers and percentages of subjects achieving titers ≥ LLOQ against each strain based on demographics. CONCLUSION: These data suggested no clinically meaningful differences in MenB-FHbp immunogenicity when administered as a three-dose schedule based on sex, ages assessed, or races evaluated. This analysis supports the continued recommended use of MenB-FHbp to prevent MenB disease in adolescents and young adults. TRIAL REGISTRATION: ClinicalTrials.gov identifiers, NCT00808028, NCT01830855, NCT01323270, NCT01461993, NCT01461980, NCT01352845, and NCT01299480.

Persistence of Immune Responses Through 36 Months in Healthy Adults After Vaccination With a Novel Staphylococcus aureus 4-Antigen Vaccine (SA4Ag).

BACKGROUND: Staphylococcus aureus causes serious health care- and community-associated disease, requiring improved preventive measures such as vaccines. The investigational S. aureus 4-antigen vaccine (SA4Ag), comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM197, recombinant mutant clumping factor A (rmClfA), and recombinant manganese transporter protein C (rP305A or rMntC), was well tolerated, inducing robust functional immune responses to all 4 antigens through 12 months postvaccination. This is a serological extension study through 36 months postvaccination. METHODS: In 2 previous studies, healthy adults received SA4Ag, SA3Ag (without rMntC), or placebo; serology was also assessed at ~24 and ~36 months postvaccination. Functional immune responses (antibody responses that facilitate killing of S. aureus or neutralize S. aureus virulence mechanisms) were assessed with opsonophagocytic activity killing assays (CP5 or CP8) and a fibrinogen-binding inhibition assay (ClfA). A competitive Luminex immunoassay assessed ClfA and rMntC responses. Adverse events within 48 hours of blood draw were recorded. RESULTS: Four hundred forty subjects (18-64 years old, 255; 65-85 years old, 185) were enrolled. At 24 and 36 months postvaccination, subjects receiving SA4Ag had substantially higher geometric mean titers (GMTs) for CP5, CP8, and ClfA vs baseline; geometric mean fold rises (GMFRs) from baseline to month 36 were 2.7-8.1. For rMntC, 36-month GMTs declined from peak levels but remained above baseline for all SA4Ag groups; GMFRs from baseline to month 36 were 1.8 and 1.5 in the younger and older cohorts, respectively. CONCLUSIONS: Persistent functional immune responses to S. aureus antigens were observed through 36 months in healthy adults. CLINICALTRIALSGOV: NCT01643941 and NCT01364571.

S. aureus colonization in healthy Australian adults receiving an investigational S. aureus 3-antigen vaccine.

OBJECTIVES: Assess Staphylococcus aureus (S. aureus) colonization in healthy Australian adults receiving an investigational S. aureus 3-antigen vaccine (SA3Ag). METHODS: In this phase 1, double-blind, sponsor-unblinded study, participants were randomized to receive a single dose (1 of 3 dose levels) of SA3Ag or placebo and a booster dose or placebo at 6 months. S. aureus isolates from nasal, perineal, and oropharyngeal swabs before and through 12 months post-vaccination were identified. RESULTS: Baseline S. aureus colonization prevalence was 30.6% (any site), with nasal carriage (27.0%) more common than oropharyngeal/perineal (3.2% each). Following initial vaccination (low-dose: 102; mid-dose: 101; high-dose: 101; placebo: 102) and booster (low-dose: 45; mid-dose: 44; high-dose: 27; placebo: 181), placebo and SA3Ag groups showed similar S. aureus carriage through 12 months. Most colonized participants (74.0%) were colonized by single spa types. Placebo and SA3Ag groups had similar persistence of colonization, with 19.6-30.7% due to single spa types. Acquisition was observed in mid- and high-dose recipients (∼20%) and low-dose and placebo recipients (∼12%). Vaccination resulted in substantial increases in antibodies to all 3 antigens, irrespective of carriage status. CONCLUSIONS: Based on descriptive analyses of this small study, SA3Ag vaccination did not impact S. aureus acquisition or carriage. Carriage status did not impact antibody responses to SA3Ag.

Persistence and 4-year boosting of the bactericidal response elicited by two- and three-dose schedules of MenB-FHbp: A phase 3 extension study in adolescents.

BACKGROUND: The period of heightened risk of invasive meningococcal disease in adolescence extends for >10 years. This study aimed to evaluate persistence of the immune response to the serogroup B meningococcal (MenB) vaccine MenB-FHbp (Trumenba®, Bivalent rLP2086) under two- and three-dose primary vaccination schedules, both of which are approved in the United States and the European Union, and to assess safety and immunogenicity of a booster dose. METHODS: This was an open-label extension study of a phase 2 randomized MenB-FHbp study (primary study). This interim analysis includes data through 1 month after booster vaccination. In the primary study, adolescents 11-18 years of age were randomized using an interactive voice or web-based response system to receive 120 µg MenB-FHbp under 0-, 1-, 6-month; 0-, 2-, 6-month; 0-, 6-month; 0-, 2-month; or 0-, 4-month schedules (termed study groups for the current analysis). For the primary study, participants were blinded to their vaccine study group allocation, but investigators and the study sponsor were unblinded. Immune responses in subjects from the primary study were evaluated through 48 months after primary vaccination (persistence stage; 17 sites in Czech Republic, Denmark, Germany, and Sweden). Safety and immunogenicity of a booster dose given at 48 months after primary vaccination (booster stage; 14 sites in Czech Republic, Denmark, and Sweden) were also assessed. Immune responses were evaluated in serum bactericidal assays with human complement (hSBAs) using four MenB test strains representative of disease-causing MenB strains in the United States and Europe and expressing factor H binding proteins (FHbps) heterologous to the vaccine antigens. The primary immunogenicity endpoints were the proportions of subjects with hSBA titers greater than or equal to the assays' lower limit of quantitation (LLOQ; 1:8 or 1:16 depending on strain) at 12, 18, 24, 36, and 48 months after primary vaccination (persistence stage) and 1 and 48 months after the primary vaccination series and 1 month after receipt of the booster dose (booster stage). Safety evaluations during the booster stage included local reactions and systemic events by severity, antipyretic use, adverse events (AEs), immediate AEs, serious AEs (SAEs), medically attended AEs (MAEs), newly diagnosed chronic medical conditions (NDCMCs), and missed days of school and work because of AEs. The modified intent-to-treat (mITT) population was used for immunogenicity evaluations in the persistence stage. The booster stage immunogenicity evaluations used the evaluable immunogenicity population; analyses were also performed in the mITT population. For the persistence stage, safety evaluations included subjects with at least one blood draw, whereas for the booster stage, they included subjects who received the booster dose and had available safety data. This trial is registered at ClinicalTrials.gov number NCT01543087. FINDINGS: A total of 465 subjects were enrolled in the persistence stage, and 271 subjects were enrolled in the booster stage. Sera for the extension phase of this interim analysis were collected from September 7, 2012 to December 7, 2015. One month after primary vaccination, 73.8-100.0% of subjects depending on study group responded with hSBA titers ≥LLOQ. Response rates declined during the 12 months after last primary vaccination and then remained stable through 48 months, with 18.0-61.3% of subjects depending on study group having hSBA titers ≥LLOQ at this time point. One month after receipt of the booster dose, 91.9-100.0% of subjects depending on study group had hSBA titers ≥LLOQ against the four primary strains individually and 91.8-98.2% had hSBA titers ≥LLOQ against all four strains combined (composite response). Geometric mean titers were higher after booster vaccination than at 1 month after primary vaccination. Immune responses were generally similar across study groups, regardless of whether a two- or three-dose primary series was received. None of the AEs (2.2-6.9% of subjects depending on study group) or NDCMCs (1.8-5.0%) that were reported during the persistence stage were considered related to the investigational product. Local reactions and systemic events were reported by 84.4-93.8% and 68.8-76.6% of subjects depending on study group, respectively, in the booster stage; these were generally similar across study groups, transient, and less frequent than after any primary vaccination. Additionally, there was no general progressive worsening in severity of reactogenicity events (ie, potentiation; ≤3 subjects per group), and reactogenicity events did not lead to any study withdrawals. No NDCMCs or immediate AEs were reported during the booster stage. AEs were reported by 3.7-12.5% of subjects depending on study group during the booster stage. The two possibly related AEs included a mild worsening of psoriasis and a severe influenza-like illness that resolved in 10 days. INTERPRETATION: Immune responses declined after the primary vaccination series; however, a substantially greater number of subjects retained protective responses at 48 months after primary vaccination compared with subjects having protective responses before vaccination. Persistence trends were similar across all 5 study groups regardless of whether a two- or three-dose primary schedule was received. Furthermore, a booster dose given 48 months after primary vaccination was safe, well-tolerated, and elicited robust immune responses indicative of immunologic memory; these responses were similar between two- and three-dose primary schedule study groups. Use of a booster dose may help further extend protection against MenB disease in adolescents. FUNDING: Pfizer Inc.

A Longitudinal Epidemiology Study of Meningococcal Carriage in Students 13 to 25 Years Old in Quebec.

Neisseria meningitidis carriage data are necessary to inform serogroup B (NmB) immunization program implementation. This longitudinal study compared detection methods to measure N. meningitidis throat carriage prevalence in Quebec from November 2010 to December 2013 using cultured swab isolates and direct swab PCR from students in ninth grade (aged 13 to 15 years; n = 534) and eleventh grade/college entry (16 to 18 years; n = 363) and in university students in dormitories (18 to 25 years; n = 360) at 3 time points per group. Meningococcal and NmB carriage rates were lower in ninth- and eleventh-grade/college entry students than university students, regardless of methodology. Genotyping cultured isolates by PCR detected NmB and non-NmB in 2.1% and 7.3% of ninth-grade students, in 1.7% and 7.2% of eleventh-grade/college entry students, and in 7.5% and 21.9% of university students, respectively. NmB acquisition rates were 1.9, 0.7, and 3.3 per 1,000 person-months across respective age groups. Most NmB isolates (94.7%, 76.9%, and 86.8%, respectively) expressed subfamily A factor H binding-protein (fHBP) variants. The most common non-NmB serogroups were NmY (1.7%/1.1%) from ninth grade and eleventh grade/college entry and NmW (2.8%) from university students. Genomic analyses detected disease-associated sequence types in carriage isolates, and carriage could persist for months. This is the largest longitudinal carriage study in Canada and the first to report fHBP variants in NmB carriage isolates in healthy Canadians. These data contribute to identification of the optimal window for NmB vaccination in precollege adolescents and provide a baseline for investigating NmB vaccination effects on carriage in this population.IMPORTANCE Disease caused by Neisseria meningitidis is associated with serious complications and a high fatality rate. Asymptomatic individuals can harbor the bacterium in the throat, a state known as "carriage," which can lead to person-to-person spread of the pathogen. This study examined N. meningitidis carriage from 2010 to 2013 among 2 groups in the Quebec City region: ninth-grade students (aged 13 to 15 years), who were also followed in their last year of high school (eleventh grade/college entry; 16 to 18 years), and university students (18 to 25 years); both groups have been shown in some other geographic regions to have high rates of carriage. This study demonstrated that N. meningitidis carriage rates were higher among university students in dormitories than ninth-grade and eleventh-grade/college entry students. Understanding carriage rates in these age groups leads to better strategies to control N. meningitidis by targeting vaccination to those responsible for transmission within the population.

Safety, tolerability, and immunogenicity of a novel 4-antigen Staphylococcus aureus vaccine (SA4Ag) in healthy Japanese adults.

A novel Staphylococcus aureus 4-antigen vaccine (SA4Ag) is under development, comprising capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to CRM197, recombinant protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (MntC). We evaluated SA4Ag safety, tolerability, and immunogenicity in Japanese adults aged 20 to 64 and 65 to 85 years. A total of 136 healthy Japanese adults (68 per age group) were randomized 1:1 to receive single-dose SA4Ag or placebo intramuscularly (Day 1). Safety assessments included reactogenicity and adverse events. The ability of the vaccine to induce immune responses that are considered functional due to their ability to facilitate the killing of S. aureus or neutralize S. aureus virulence mechanisms was assessed using 5 different antigen-specific assays. SA4Ag was well tolerated in both age groups, with no safety concerns. At Day 29, > 85% of SA4Ag recipients in each age group achieved predefined thresholds for each antigen. Antibody geometric mean-fold rises from baseline to Day 29 in SA4Ag groups were: > 80 and > 30 for CP5 and CP8 (opsonophagocytic activity assay), > 10 for ClfA (fibrinogen-binding inhibition assay), and > 15 and > 7 for ClfA and MntC (competitive Luminex® immunoassay), respectively. Antibody titers decreased through Month 12 but remained well above baseline and placebo levels. SA4Ag had an acceptable safety profile and induced rapid and robust functional immune responses in both age groups. These results support ongoing development of SA4Ag for the prevention of invasive S. aureus disease in elective-surgery patients in Japan, North America, and Europe.

From research to licensure and beyond: clinical development of MenB-FHbp, a broadly protective meningococcal B vaccine.

INTRODUCTION: Given the characteristics of meningococcal carriage and transmission and the sudden, often severe onset and long-term consequences of disease, vaccination can most effectively provide large-scale control of invasive disease. Six serogroups (A, B, C, W, X, and Y) cause nearly all meningococcal disease globally. Capsular polysaccharide conjugate vaccines can prevent serogroups A, C, W, and Y disease. More recently, recombinant protein vaccines for preventing serogroup B meningococcal (MenB) disease have become available, with a major target of vaccine-induced immune response for both vaccines being bacterial factor H binding protein (FHbp). Importantly, FHbp segregates into only two distinct subfamilies (A [also classified as variants 2 and 3] and B [variant 1]). This review summarizes the complete clinical development program supporting licensure of MenB-FHbp (Trumenba®, Bivalent rLP2086), the only MenB vaccine containing antigens from both FHbp subfamilies. Areas covered: Eleven published clinical studies assessing MenB-FHbp efficacy and safety among 20,803 adolescents and adults are examined. Particular focus is on the methodology of immunogenicity assessments used as a surrogate for clinical efficacy. Expert commentary: Clinical studies in adolescents and adults consistently demonstrated MenB-FHbp safety and induction of immunologic responses against antigenically and epidemiologically diverse MenB isolates, supporting licensure and immunization recommendations.

A Bivalent Meningococcal B Vaccine in Adolescents and Young Adults.

BACKGROUND: MenB-FHbp is a licensed meningococcal B vaccine targeting factor H-binding protein. Two phase 3 studies assessed the safety of the vaccine and its immunogenicity against diverse strains of group B meningococcus. METHODS: We randomly assigned 3596 adolescents (10 to 18 years of age) to receive MenB-FHbp or hepatitis A virus vaccine and saline and assigned 3304 young adults (18 to 25 years of age) to receive MenB-FHbp or saline at baseline, 2 months, and 6 months. Immunogenicity was assessed in serum bactericidal assays that included human complement (hSBAs). We used 14 meningococcal B test strains that expressed vaccine-heterologous factor H-binding proteins representative of meningococcal B epidemiologic diversity; an hSBA titer of at least 1:4 is the accepted correlate of protection. The five primary end points were the proportion of participants who had an increase in their hSBA titer for each of 4 primary strains by a factor of 4 or more and the proportion of those who had an hSBA titer at least as high as the lower limit of quantitation (1:8 or 1:16) for all 4 strains combined after dose 3. We also assessed the hSBA responses to the primary strains after dose 2; hSBA responses to the 10 additional strains after doses 2 and 3 were assessed in a subgroup of participants only. Safety was assessed in participants who received at least one dose. RESULTS: In the modified intention-to-treat population, the percentage of adolescents who had an increase in the hSBA titer by a factor of 4 or more against each primary strain ranged from 56.0 to 85.3% after dose 2 and from 78.8 to 90.2% after dose 3; the percentages of young adults ranged from 54.6 to 85.6% and 78.9 to 89.7%, after doses 2 and 3, respectively. Composite responses after doses 2 and 3 in adolescents were 53.7% and 82.7%, respectively, and those in young adults were 63.3% and 84.5%, respectively. Responses to the 4 primary strains were predictive of responses to the 10 additional strains. Most of those who received MenB-FHbp reported mild or moderate pain at the vaccination site. CONCLUSIONS: MenB-FHbp elicited bactericidal responses against diverse meningococcal B strains after doses 2 and 3 and was associated with more reactions at the injection site than the hepatitis A virus vaccine and saline. (Funded by Pfizer; ClinicalTrials.gov numbers, NCT01830855 and NCT01352845 ).

SA4Ag, a 4-antigen Staphylococcus aureus vaccine, rapidly induces high levels of bacteria-killing antibodies.

BACKGROUND: Staphylococcus aureus is a leading cause of healthcare-associated infections. No preventive vaccine is currently licensed. SA4Ag is an investigational 4-antigen S. aureus vaccine, composed of capsular polysaccharide conjugates of serotypes 5 and 8 (CP5 and CP8), recombinant surface protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (rMntC). This Phase 1 study aimed to confirm the safety and immunogenicity of SA4Ag produced by the final manufacturing process before efficacy study initiation in a surgical population. METHODS: Healthy adults (18-<65years) received one intramuscular SA4Ag injection. Serum functional antibodies were measured at baseline and Day 29 post-vaccination. An opsonophagocytic activity (OPA) assay measured the ability of vaccine-induced antibodies to CP5 and CP8 to kill S. aureus clinical isolates. For MntC and ClfA, antigen-specific immunogenicity was assessed via competitive Luminex® immunoassay (cLIA) and via fibrinogen-binding inhibition (FBI) assay for ClfA only. Reactogenicity and adverse event data were collected. RESULTS: One hundred participants were vaccinated. SA4Ag was well tolerated, with a satisfactory safety profile. On Day 29, OPA geometric mean titers (GMTs) were 45,738 (CP5, 95% CI: 38,078-54,940) and 42,652 (CP8, 95% CI: 32,792-55,477), consistent with 69.2- and 28.9-fold rises in bacteria-killing antibodies, respectively; cLIA GMTs were 2064.4 (MntC, 95% CI: 1518.2-2807.0) and 3081.4 (ClfA, 95% CI: 2422.2-3920.0), consistent with 19.6- and 12.3-fold rises, respectively. Similar to cLIA results, ClfA FBI titers rose 11.0-fold (GMT: 672.2, 95% CI: 499.8-904.2). The vast majority of participants achieved the pre-defined biologically relevant thresholds: CP5: 100%; CP8: 97.9%, ClfA: 87.8%; and MntC 96.9%. CONCLUSIONS: SA4Ag was safe, well tolerated, and rapidly induced high levels of bacteria-killing antibodies in healthy adults. A Phase 2B efficacy trial in adults (18-85years) undergoing elective spinal fusion is ongoing to assess SA4Ag's ability to prevent postoperative invasive surgical site and bloodstream infections caused by S. aureus. Clinicaltrials.gov Identifier: NCT02364596.

Meningococcal serogroup B vaccines: Estimating breadth of coverage.

Neisseria meningitidis serogroup B (MenB) is an important cause of invasive meningococcal disease. The development of safe and effective vaccines with activity across the diversity of MenB strains has been challenging. While capsular polysaccharide conjugate vaccines have been highly successful in the prevention of disease due to meningococcal serogroups A, C, W, and Y, this approach has not been possible for MenB owing to the poor immunogenicity of the MenB capsular polysaccharide. Vaccines based on outer membrane vesicles have been successful in the prevention of invasive MenB disease caused by the single epidemic strain from which they were derived, but they do not confer broad protection against diverse MenB strains. Thus, alternative approaches to vaccine development have been pursued to identify vaccine antigens that can provide broad protection against the epidemiologic and antigenic diversity of invasive MenB strains. Human factor H binding protein (fHBP) was found to be such an antigen, as it is expressed on nearly all invasive disease strains of MenB and can induce bactericidal responses against diverse MenB strains. A bivalent vaccine (Trumenba®, MenB-FHbp, bivalent rLP2086) composed of equal amounts of 2 fHBP variants from each of the 2 immunologically diverse subfamilies of fHBP (subfamilies A and B) was the first MenB vaccine licensed in the United States under an accelerated approval pathway for prevention of invasive MenB disease. Due to the relatively low incidence of meningococcal disease, demonstration of vaccine efficacy for the purposes of licensure of bivalent rLP2086 was based on vaccine-elicited bactericidal activity as a surrogate marker of efficacy, as measured in vitro by the serum bactericidal assay using human complement. Because bacterial surface proteins such as fHBP are antigenically variable, an important component for evaluation and licensure of bivalent rLP2086 included stringent criteria for assessment of breadth of coverage across antigenically diverse and epidemiologically important MenB strains. This review describes the rigorous approach used to assess broad coverage of bivalent rLP2086. Alternative nonfunctional assays proposed for assessing vaccine coverage are also discussed.

Safety, tolerability, and immunogenicity of a 4-antigen Staphylococcus aureus vaccine (SA4Ag): Results from a first-in-human randomised, placebo-controlled phase 1/2 study.

BACKGROUND: A prophylactic Staphylococcus aureus four-antigen vaccine (SA4Ag) is under development for prevention of invasive S. aureus disease. A preliminary S. aureus three-antigen vaccine (SA3Ag) was reformulated to include a novel manganese transporter protein (MntC or rP305A). This study describes the first-in-human dose-finding, safety, and immunogenicity results for SA4Ag. METHODS: In this double-blind, sponsor-unblind, placebo-controlled, phase 1/2 study, 454 healthy adults aged 18-64years were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; antigen-specific immunogenicity was assessed using a four-plex competitive Luminex® immunoassay (cLIA). RESULTS: A high proportion of SA4Ag recipients met the pre-defined antibody thresholds for each antigen at Day 29. A substantial and dose-level dependent immune response was observed for rP305A, with up to 18-fold rises in cLIA titres at Day 29. Robust functional responses were demonstrated, with >80-fold and >20-fold rises in OPA assay titres at Day 29 using S. aureus strains expressing capsular polysaccharide serotypes 5 and 8, respectively. Durable antibody responses were observed through month 12, gradually waning from peak levels achieved by days 11-15. SA4Ag was well tolerated, and no vaccine-related serious adverse events were reported. CONCLUSIONS: Single-dose vaccination of SA4Ag in healthy adults aged 18-64years safely induced rapid and robust functional immune responses that were durable through month 12, supporting further development of this vaccine. TRIAL REGISTRATION NUMBER: NCT01364571.

Meningococcal serogroup B-specific responses after vaccination with bivalent rLP2086: 4 year follow-up of a randomised, single-blind, placebo-controlled, phase 2 trial.

BACKGROUND: Bivalent rLP2086 is a recombinant factor H binding protein-based vaccine approved in the USA for prevention of meningococcal serogroup B disease in 10-25-year-olds. We aimed to assess the persistence of bactericidal antibodies up to 4 years after a three-dose schedule of bivalent rLP2086. METHODS: We did this randomised, single-blind, placebo-controlled, phase 2 trial at 25 sites in Australia, Poland, and Spain. In stage 1 of the study (February, 2009-May, 2010), healthy adolescents (aged 11-18 years) were randomly assigned, via an interactive voice and web-response system with computer-generated sequential random numbers, to receive either ascending doses of vaccine (60 µg, 120 µg, and 200 µg) or placebo at months 0, 2, and 6. Dispensing staff were not masked to group allocation, but allocation was concealed from principal investigators, participants and their guardians, and laboratory personnel. In stage 2 of the study (reported here), we enrolled healthy adolescents who had received three doses of 120 µg bivalent rLP2086 (the optimum dose level identified in stage 1) or saline. Immunogenicity was determined in serum bactericidal antibody assay using human complement (hSBA) by use of four meningococcal serogroup B test strains expressing vaccine-heterologous factor H binding protein variants: PMB80 (A22), PMB2001 (A56), PMB2948 (B24), and PMB2707 (B44). Immunogenicity in stage 2 was assessed at months 6, 12, 24, and 48 post-vaccination. We did analysis by intention to treat. This trial is registered as ClinicalTrials.gov number NCT00808028. FINDINGS: Between March 17, 2010, and Feb 8, 2011, 170 participants who received 120 µg of bivalent rLP2086 and 80 participants who received placebo in stage 1 of the study were entered into stage 2; 210 participants completed stage 2 up to 48 months. 1 month after the third vaccination, 93% (n=139/149) to 100% (n=48/48) of vaccine recipients achieved protective hSBA titres equal to or greater than the lower limit of quantification to each test strain, compared with 0% (n=0/25) to 35% (n=8/23) of control recipients. Despite initial declines in seroprotective hSBA titres for all four test strains, for three test strains (A22, A56, and B24), more than 50% of bivalent rLP2086 recipients continued to achieve titres equal to or greater than the lower limit of quantification at months 6 (57% [n=93/163] to 89% [n=42/47]), 12 (54% [n=84/155] to 69% [n=33/48]), 24 (53% [n=26/49] to 54% [n=82/152]), and 48 (51% [n=24/47] to 59% [n=79/134]); corresponding values in the control group were 14% (n=11/80) to 22% (n=5/23) at month 6, 13% (n=10/78) to 29% (n=22/76) at month 12, 16% (n=12/74) to 36% (n=8/22) at month 24, and 24% (n=16/68) to 35% (n=8/23) at month 48. For test strain B44, hSBA titres equal to or greater than the lower limit of quantification were shown in 37% (n=18/49) of vaccine recipients at 6 months, in 29% (n=14/48) at 12 months, in 22% (n=11/49) at 24 months, and in 20% (n=10/49) at 48 months, compared with 0% (n=0/25) of control recipients at month 6, 4% (n=1/25) at months 12 and 24, and 12% (n=3/25) at month 48. Adverse events were reported in seven (4%) of 170 participants in the bivalent rLP2086 group and two (3%) of 80 participants in the control group; no event was deemed related to vaccine. INTERPRETATION: After three doses of bivalent rLP2086, protective hSBA titres above the correlate of protection (≥1/4) were elicited up to 4 years in more than 50% of participants for three of four meningococcal serogroup B test strains representative of disease-causing meningococci expressing vaccine-heterologous antigens. Further studies will be needed to assess possible herd immunity effects with meningococcal serogroup B vaccines and the need for a booster dose to sustain individual protection against invasive meningococcal disease. FUNDING: Pfizer.

Safety, tolerability, and immunogenicity of a single dose 4-antigen or 3-antigen Staphylococcus aureus vaccine in healthy older adults: Results of a randomised trial.

BACKGROUND: The decline in immune function with age is a challenge to vaccine development. Following an initial study in adults aged 18-64years, this study evaluated the safety and immunogenicity of Staphylococcus aureus (S. aureus) 4-antigen (SA4Ag) and 3-antigen (SA3Ag) vaccine in older adults. SA3Ag included capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to the nontoxic mutant form of diphtheria toxin (CRM197) and a recombinant version of clumping factor A (ClfA). SA4Ag included these antigens, with the addition of a recombinant manganese transporter C (rP305A or MntC). Both vaccines were unadjuvanted. METHODS: In this double-blind, sponsor-unblinded, placebo-controlled, phase 1/2 study, 284 healthy adults (aged 65-85years) were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A, SA3Ag, or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; immunogenicity was also assessed using a competitive Luminex® immunoassay (cLIA). T-cell responses were measured in a small subgroup of subjects using intracellular cytokine staining (ICS) assays. RESULTS: The results demonstrated rapid and robust functional immune responses to all antigens in healthy older adults. A high proportion of active vaccine recipients met the pre-defined antibody thresholds for each antigen at Day 29. SA4Ag elicited a dose-level response to rP305A with up to a 13-fold rise in cLIA titres at Day 29. Opsonophagocytic activity (OPA) assays showed >50- and >20-fold rises in functional titres using S. aureus strains expressing CP5 and CP8, respectively, at Day 29. T-cell cytokine responses were not substantially above background levels. There were no safety concerns in this study population and no increases in adverse events with higher rP305A dose levels. CONCLUSIONS: Single-dose vaccination of SA4Ag and SA3Ag in healthy adults aged 65-85years safely induced rapid and robust functional immune responses, supporting further development of SA4Ag for the prevention of S. aureus disease in adults up to age 85years. TRIAL REGISTRATION NUMBER: NCT01643941.

Safety and immunogenicity of a booster dose of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults: A randomized phase 1 study.

OBJECTIVE: A 2-stage, phase 1, randomized, placebo-controlled study in healthy adults to assess immunogenicity and safety of a booster dose at three dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) containing recombinant clumping factor A (ClfA) and capsular polysaccharides 5 and 8 (CP5 and CP8) conjugated to a diphtheria toxoid. METHODS: Six months after initial single vaccination, in Stage 2, SA3Ag recipients were randomized (1:1) to booster vaccination or placebo, while Stage 1 placebo recipients received placebo again. Pre- and post-vaccination blood samples were analyzed. RESULTS: In Stage 2 (n = 345), pre-booster CP5 and CP8 titers remained high with no increase post-booster. ClfA titers remained high after initial vaccination and increased post-booster, approaching the peak response to the initial dose. Post-booster local reactions were more frequent and of greater severity than reported after the initial vaccination, particularly for the high-dose level recipients. Post hoc analysis showed no dose-response pattern and no obvious association between diphtheria toxoid titers and local reactions after initial or booster vaccination. CONCLUSION: Immune responses after the initial vaccination persisted for the 12 months studied, with little additional response after the booster dose at 6 months. Post-booster injection site reactions were more frequent and more severe but self-limiting. CLINICALTRIALS. GOV IDENTIFIER: NCT01018641.

Approach to the Discovery, Development, and Evaluation of a Novel Neisseria meningitidis Serogroup B Vaccine.

In this chapter, we describe a research and development pathway to identify and demonstrate the efficacy of a Neisseria meningitidis non-capsular vaccine, the recently licensed N. meningitidis serogroup B (MnB) vaccine, Trumenba(®). While other approaches have been followed in the identification of a MnB vaccine (Pizza et al. Science 287:1816-1820, 2000), the methods described here reflect the distinctive approach and experiences in discovering and developing Trumenba(®). In contrast to the development and licensure of polysaccharide-conjugate vaccines against meningococcal serotypes A, C, W, and Y, the development of a vaccine to produce broadly protective antibodies against meningococcal serogroup B has proved difficult, due to the antigenic mimicry of the serogroup B polysaccharide capsule, which is composed of polysialic acid structures similar to those expressed on human neuronal cells. Early development efforts for these vaccines failed because the MnB polysaccharide structures resemble autoantigens and thus were poorly immunogenic. The development of an MnB vaccine has therefore focused on non-polysaccharide approaches. It was critical to identify MnB cell surface-exposed antigens capable of inducing a protective response against diverse, circulating strains of invasive MnB to ensure global coverage. Once candidate antigens were identified, it was important to characterize antigenic variation and expression levels, and subsequently to assure that antigens were expressed broadly among diverse clinical isolates. Prior to the initiation of clinical trials in humans, candidate vaccine antigens were tested in functional immunogenicity assays and yielded responses that were correlated with protection from meningococcal disease. These functional immunogenicity assays (serum bactericidal assays using human complement, hSBAs) measure the titer of complement-dependent bactericidal antibodies in serum from immunized test animals using diverse clinical MnB isolates as targets. Following optimization of vaccine antigenic components based on hSBA responses in preclinical models, animal toxicology tests were performed. Initial clinical studies (Phase 1 and 2) subsequently provided data to support (1) safety and immunogenicity of the vaccine formulation, and (2) the dose and schedule. Phase 3 clinical trials were carried out in the target populations to provide the clinical confirmation of safety and efficacy required for vaccine licensure.