Amplitude-determined seizure-threshold, electric field modeling, and electroconvulsive therapy antidepressant and cognitive outcomes.

Electroconvulsive therapy (ECT) pulse amplitude, which dictates the induced electric field (E-field) magnitude in the brain, is presently fixed at 800 or 900 milliamperes (mA) without clinical or scientific rationale. We have previously demonstrated that increased E-field strength improves ECT's antidepressant effect but worsens cognitive outcomes. Amplitude-determined seizure titration may reduce the E-field variability relative to fixed amplitude ECT. In this investigation, we assessed the relationships among amplitude-determined seizure-threshold (STa), E-field magnitude, and clinical outcomes in older adults (age range 50 to 80 years) with depression. Subjects received brain imaging, depression assessment, and neuropsychological assessment pre-, mid-, and post-ECT. STa was determined during the first treatment with a Soterix Medical 4×1 High Definition ECT Multi-channel Stimulation Interface (Investigation Device Exemption: G200123). Subsequent treatments were completed with right unilateral electrode placement (RUL) and 800 mA. We calculated Ebrain defined as the 90th percentile of E-field magnitude in the whole brain for RUL electrode placement. Twenty-nine subjects were included in the final analyses. Ebrain per unit electrode current, Ebrain/I, was associated with STa. STa was associated with antidepressant outcomes at the mid-ECT assessment and bitemporal electrode placement switch. Ebrain/I was associated with changes in category fluency with a large effect size. The relationship between STa and Ebrain/I extends work from preclinical models and provides a validation step for ECT E-field modeling. ECT with individualized amplitude based on E-field modeling or STa has the potential to enhance neuroscience-based ECT parameter selection and improve clinical outcomes.

Electric field distribution predicts efficacy of accelerated intermittent theta burst stimulation for late-life depression.

Introduction: Repetitive transcranial magnetic stimulation (rTMS) is a promising intervention for late-life depression (LLD) but may have lower rates of response and remission owing to age-related brain changes. In particular, rTMS induced electric field strength may be attenuated by cortical atrophy in the prefrontal cortex. To identify clinical characteristics and treatment parameters associated with response, we undertook a pilot study of accelerated fMRI-guided intermittent theta burst stimulation (iTBS) to the right dorsolateral prefrontal cortex in 25 adults aged 50 or greater diagnosed with LLD and qualifying to receive clinical rTMS. Methods: Participants underwent baseline behavioral assessment, cognitive testing, and structural and functional MRI to generate individualized targets and perform electric field modeling. Forty-five sessions of iTBS were delivered over 9 days (1800 pulses per session, 50-min inter-session interval). Assessments and testing were repeated after 15 sessions (Visit 2) and 45 sessions (Visit 3). Primary outcome measure was the change in depressive symptoms on the Inventory of Depressive Symptomatology-30-Clinician (IDS-C-30) from Visit 1 to Visit 3. Results: Overall there was a significant improvement in IDS score with the treatment (Visit 1: 38.6; Visit 2: 31.0; Visit 3: 21.3; mean improvement 45.5%) with 13/25 (52%) achieving response and 5/25 (20%) achieving remission (IDS-C-30 < 12). Electric field strength and antidepressant effect were positively correlated in a subregion of the ventrolateral prefrontal cortex (VLPFC) (Brodmann area 47) and negatively correlated in the posterior dorsolateral prefrontal cortex (DLPFC). Conclusion: Response and remission rates were lower than in recently published trials of accelerated fMRI-guided iTBS to the left DLPFC. These results suggest that sufficient electric field strength in VLPFC may be a contributor to effective rTMS, and that modeling to optimize electric field strength in this area may improve response and remission rates. Further studies are needed to clarify the relationship of induced electric field strength with antidepressant effects of rTMS for LLD.

Transcranial direct current stimulation modulates working memory and prefrontal-insula connectivity after mild-moderate traumatic brain injury.

Background: Persistent posttraumatic symptoms (PPS) may manifest after a mild-moderate traumatic brain injury (mmTBI) even when standard brain imaging appears normal. Transcranial direct current stimulation (tDCS) represents a promising treatment that may ameliorate pathophysiological processes contributing to PPS. Objective/Hypothesis: We hypothesized that in a mmTBI population, active tDCS combined with training would result in greater improvement in executive functions and post-TBI cognitive symptoms and increased resting state connectivity of the stimulated region, i.e., left dorsolateral prefrontal cortex (DLPFC) compared to control tDCS. Methods: Thirty-four subjects with mmTBI underwent baseline assessments of demographics, symptoms, and cognitive function as well as resting state functional magnetic resonance imaging (rsfMRI) in a subset of patients (n = 24). Primary outcome measures included NIH EXAMINER composite scores, and the Neurobehavioral Symptom Inventory (NSI). All participants received 10 daily sessions of 30 min of executive function training coupled with active or control tDCS (2 mA, anode F3, cathode right deltoid). Imaging and assessments were re-obtained after the final training session, and assessments were repeated after 1 month. Mixed-models linear regression and repeated measures analyses of variance were calculated for main effects and interactions. Results: Both active and control groups demonstrated improvements in executive function (EXAMINER composite: p < 0.001) and posttraumatic symptoms (NSI cognitive: p = 0.01) from baseline to 1 month. Active anodal tDCS was associated with greater improvements in working memory reaction time compared to control (p = 0.007). Reaction time improvement correlated significantly with the degree of connectivity change between the right DLPFC and the left anterior insula (p = 0.02). Conclusion: Anodal tDCS improved reaction time on an online working memory task in a mmTBI population, and decreased connectivity between executive network and salience network nodes. These findings generate important hypotheses for the mechanism of recovery from PPS after mild-moderate TBI.

Neurodegenerative Disease Treatment Drug PBT2 Breaks Intrinsic Polymyxin Resistance in Gram-Positive Bacteria.

Gram-positive bacteria do not produce lipopolysaccharide as a cell wall component. As such, the polymyxin class of antibiotics, which exert bactericidal activity against Gram-negative pathogens, are ineffective against Gram-positive bacteria. The safe-for-human-use hydroxyquinoline analog ionophore PBT2 has been previously shown to break polymyxin resistance in Gram-negative bacteria, independent of the lipopolysaccharide modification pathways that confer polymyxin resistance. Here, in combination with zinc, PBT2 was shown to break intrinsic polymyxin resistance in Streptococcus pyogenes (Group A Streptococcus; GAS), Staphylococcus aureus (including methicillin-resistant S. aureus), and vancomycin-resistant Enterococcus faecium. Using the globally disseminated M1T1 GAS strain 5448 as a proof of principle model, colistin in the presence of PBT2 + zinc was shown to be bactericidal in activity. Any resistance that did arise imposed a substantial fitness cost. PBT2 + zinc dysregulated GAS metal ion homeostasis, notably decreasing the cellular manganese content. Using a murine model of wound infection, PBT2 in combination with zinc and colistin proved an efficacious treatment against streptococcal skin infection. These findings provide a foundation from which to investigate the utility of PBT2 and next-generation polymyxin antibiotics for the treatment of Gram-positive bacterial infections.

Electroconvulsive therapy, electric field, neuroplasticity, and clinical outcomes.

Electroconvulsive therapy (ECT) remains the gold-standard treatment for patients with depressive episodes, but the underlying mechanisms for antidepressant response and procedure-induced cognitive side effects have yet to be elucidated. Such mechanisms may be complex and involve certain ECT parameters and brain regions. Regarding parameters, the electrode placement (right unilateral or bitemporal) determines the geometric shape of the electric field (E-field), and amplitude determines the E-field magnitude in select brain regions (e.g., hippocampus). Here, we aim to determine the relationships between hippocampal E-field strength, hippocampal neuroplasticity, and antidepressant and cognitive outcomes. We used hippocampal E-fields and volumes generated from a randomized clinical trial that compared right unilateral electrode placement with different pulse amplitudes (600, 700, and 800 mA). Hippocampal E-field strength was variable but increased with each amplitude arm. We demonstrated a linear relationship between right hippocampal E-field and right hippocampal neuroplasticity. Right hippocampal neuroplasticity mediated right hippocampal E-field and antidepressant outcomes. In contrast, right hippocampal E-field was directly related to cognitive outcomes as measured by phonemic fluency. We used receiver operating characteristic curves to determine that the maximal right hippocampal E-field associated with cognitive safety was 112.5 V/m. Right hippocampal E-field strength was related to the whole-brain ratio of E-field strength per unit of stimulation current, but this whole-brain ratio was unrelated to antidepressant or cognitive outcomes. We discuss the implications of optimal hippocampal E-field dosing to maximize antidepressant outcomes and cognitive safety with individualized amplitudes.

Electroconvulsive Therapy Pulse Amplitude and Clinical Outcomes.

INTRODUCTION: Electroconvulsive therapy (ECT) pulse amplitude, which determines the induced electric field magnitude in the brain, is currently set at 800-900 milliamperes (mA) on modern ECT devices without any clinical or scientific rationale. The present study assessed differences in depression and cognitive outcomes for three different pulse amplitudes during an acute ECT series. We hypothesized that the lower amplitudes would maintain the antidepressant efficacy of the standard treatment and reduce the risk of neurocognitive impairment. METHODS: This double-blind investigation randomized subjects to three treatment arms: 600, 700, and 800 mA (active comparator). Clinical, cognitive, and imaging assessments were conducted pre-, mid- and post-ECT. Subjects had a diagnosis of major depressive disorder, age range between 50 and 80 years, and met clinical indication for ECT. RESULTS: The 700 and 800 mA arms had improvement in depression outcomes relative to the 600 mA arm. The amplitude groups showed no differences in the primary cognitive outcome variable, the Hopkins Verbal Learning Test-Revised (HVLT-R) retention raw score. However, secondary cognitive outcomes such as the Delis Kaplan Executive Function System Letter and Category Fluency measures demonstrated cognitive impairment in the 800 mA arm. DISCUSSION: The results demonstrated a dissociation of depression (higher amplitudes better) and cognitive (lower amplitudes better) related outcomes. Future work is warranted to elucidate the relationship between amplitude, electric field, neuroplasticity, and clinical outcomes.

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.

Microfabrication of monolithic wafer-level miniaturized millimeter-wave air-filled half-mode waveguide filter based on the inward curving split ring resonator array.

In this paper, we propose a miniaturized monolithic bandpass filter utilizing an air-filled half-mode waveguide and an inward curving split ring resonator array in the millimeter-wave band. The waveguide blocks the wave below cutoff frequency and the uniplanar array forms a rejection band above the transmission band. The microfabrication process of the filter adopts photoimageable technology and the combination of films with different thicknesses to build a 3D structure. The measured prototype has a center frequency at 65.5 GHz with a 3 dB fractional bandwidth of 30.7%. The minimum insertion loss is 2.1 dB. The proposed component offers excellent performance including a wide transmission band, a low pass-band insertion loss, an excellent isolation in the stop-band, and a steep roll-off at the upper cutoff frequency. Besides, due to the scalability of the waveguide and periodic array, this filter can be adapted for other frequency ranges.

Selection of diverse strains to assess broad coverage of the bivalent FHbp meningococcal B vaccine.

MenB-FHbp is a recombinant meningococcal serogroup B (MenB) vaccine composed of 2 factor H binding proteins (FHbps). Meningococcal vaccines targeting polysaccharide serogroup A, C, Y, and W capsules were licensed upon confirmation of bactericidal antibody induction after initial efficacy studies with serogroup A and C vaccines. Unlike meningococcal polysaccharide vaccines, wherein single strains demonstrated bactericidal antibodies per serogroup for each vaccine, MenB-FHbp required a more robust approach to demonstrate that bactericidal antibody induction could kill strains with diverse FHbp sequences. Serum bactericidal assays using human complement were developed for 14 MenB strains, representing breadth of meningococcal FHbp diversity of ~80% of circulating MenB strains. This work represents an innovative approach to license a non-toxin protein vaccine with 2 antigens representing a single virulence factor by an immune correlate, and uniquely demonstrates that such a vaccine provides coverage across bacterial strains by inducing broadly protective antibodies.

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.

Persistence of antibodies 1 year after sequential administration of the 13-valent pneumococcal conjugate vaccine and the 23-valent pneumococcal polysaccharide vaccine in adults.

Vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) followed ≥ 1 year by the 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for immunocompetent adults ≥ 65 years of age in the United States. This study assessed antipneumococcal opsonophagocytic activity (OPA) geometric mean titers (GMTs) to PCV13 in PPSV23-naive and PPSV23-preimmunized adults 1 year after a second vaccine dose. Two parent studies were conducted previously: (1) PPSV23 vaccine-naive subjects (60-64 years of age at enrollment) received PCV13 followed by PCV13 or PPSV23 1 year later or PPSV23 followed by PCV13 1 year later; and (2) subjects (≥ 70 years of age at enrollment) vaccinated with PPSV23 ≥ 5 years before study entry received PCV13 or PPSV23 followed by PCV13 1 year later. Overall, 962 subjects (PPSV23-naive, n = 519; PPSV23-preimmunized, n = 443) who received both vaccinations in the parent studies were enrolled. Numerically higher OPA GMTs persisted for at least 1 year after administration of PCV13 as the initial vaccine (PCV13/PPSV23 or PCV13/PCV13) compared with those who received PPSV23 either 1 or 5 years prior (PPSV23/PCV13). This impairment in antibody responses to subsequent PCV13 vaccination produced by initial PPSV23 vaccination persisted for at least 1 year. OPA GMTs were numerically higher for most serotypes 1 year after 2 doses of PCV13 compared with 1 year after the first PCV13 dose. These data suggest PCV13 should be given first if both vaccines are to be administered, higher immune responses were achieved when PCV13 was given first and persisted at least 1 year (ClinicalTrials.gov Identifier: NCT01025336).

The bivalent factor H binding protein meningococcal serogroup B vaccine elicits bactericidal antibodies against representative non-serogroup B meningococci.

MenB-FHbp (Trumenba®; bivalent rLP2086) is a meningococcal serogroup B vaccine containing 2 variants of the recombinant lipidated factor H binding protein (FHbp) antigen. The expression of FHbp, an outer membrane protein, is not restricted to serogroup B strains of Neisseria meningitidis (MenB). This study investigated whether antibodies elicited by MenB-FHbp vaccination also protect against non-MenB strains. Immunological responses were assessed in serum bactericidal assays using human complement (hSBAs) with non-MenB disease-causing test strains from Europe, Africa, and the United States. Importantly, FHbp variant distribution varies among meningococcal serogroups; therefore, strains that code for serogroup-specific prevalent variants (ie, representative of the 2 antigenically distinct FHbp subfamilies, designated subfamily A and subfamily B) and with moderate levels of FHbp surface expression were selected for testing by hSBA. After 2 or 3 doses of MenB-FHbp, 53% to 100% of individuals had bactericidal responses (hSBA titers ≥ 1:8) against meningococcal serogroup C, W, Y, and X strains, and 20% to 28% had bactericidal responses against serogroup A strains; in fact, these bactericidal responses elicited by MenB-FHbp antibodies against non-MenB strains, including strains associated with emerging disease, were greater than the serological correlate of protection for meningococcal disease (ie, hSBA titers ≥ 1:4). This is in comparison to a quadrivalent polysaccharide conjugate vaccine, MCV4 (Menactra®, targeting meningococcal serogroups A, C, W, and Y), which elicited bactericidal responses of 90% to 97% against the serogroup A, C, W, and Y strains and had no activity against serogroup X. Together, these results provide clinical evidence that MenB-FHbp may protect against meningococcal disease regardless of serogroup.

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.

Predicting the Susceptibility of Meningococcal Serogroup B Isolates to Bactericidal Antibodies Elicited by Bivalent rLP2086, a Novel Prophylactic Vaccine.

Bivalent rLP2086 (Trumenba), a vaccine for prevention of Neisseria meningitidis serogroup B (NmB) disease, was licensed for use in adolescents and young adults after it was demonstrated that it elicits antibodies that initiate complement-mediated killing of invasive NmB isolates in a serum bactericidal assay with human complement (hSBA). The vaccine consists of two factor H binding proteins (fHBPs) representing divergent subfamilies to ensure broad coverage. Although it is the surrogate of efficacy, an hSBA is not suitable for testing large numbers of strains in local laboratories. Previously, an association between the in vitro fHBP surface expression level and the susceptibility of NmB isolates to killing was observed. Therefore, a flow cytometric meningococcal antigen surface expression (MEASURE) assay was developed and validated by using an antibody that binds to all fHBP variants from both fHBP subfamilies and accurately quantitates the level of fHBP expressed on the cell surface of NmB isolates with mean fluorescence intensity as the readout. Two collections of invasive NmB isolates (n = 1,814, n = 109) were evaluated in the assay, with the smaller set also tested in hSBAs using individual and pooled human serum samples from young adults vaccinated with bivalent rLP2086. From these data, an analysis based on fHBP variant prevalence in the larger 1,814-isolate set showed that >91% of all meningococcal serogroup B isolates expressed sufficient levels of fHBP to be susceptible to bactericidal killing by vaccine-induced antibodies.IMPORTANCE Bivalent rLP2086 (Trumenba) vaccine, composed of two factor H binding proteins (fHBPs), was recently licensed for the prevention of N. meningitidis serogroup B (NmB) disease in individuals 10 to 25 years old in the United States. This study evaluated a large collection of NmB isolates from the United States and Europe by using a flow cytometric MEASURE assay to quantitate the surface expression of the vaccine antigen fHBP. We find that expression levels and the proportion of strains above the level associated with susceptibility in an hSBA are generally consistent across these geographic regions. Thus, the assay can be used to predict which NmB isolates are susceptible to killing in the hSBA and therefore is able to demonstrate an fHBP vaccine-induced bactericidal response. This work significantly advances our understanding of the potential for bivalent rLP2086 to provide broad coverage against diverse invasive-disease-causing NmB isolates.

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 ).

Bactericidal activity of sera from adolescents vaccinated with bivalent rLP2086 against meningococcal serogroup B outbreak strains from France.

OBJECTIVES: Bivalent rLP2086 (Trumenba®; MenB-FHbp), composed of two factor H binding proteins (FHbps), is a vaccine approved in the United States for prevention of Neisseria meningitidis serogroup B (MnB) invasive meningococcal disease (IMD). Bactericidal activity of sera from subjects vaccinated with bivalent rLP2086 was assessed against MnB isolates from recent disease outbreaks in France. METHODS: MnB isolates from IMD cases were characterized by whole genome sequencing and FHbp expression was assessed using a flow cytometry-based assay. Sera from subjects (11-<19years old) vaccinated with bivalent rLP2086 at 0, 2, and 6months were evaluated. Bactericidal activity was measured in serum bactericidal assays using human complement (hSBAs). The response rate (RR) represents the percentage of subjects with an hSBA titer ⩾1:4. RESULTS: The six MnB outbreak isolates expressed diverse FHbp variants: A22, B03, B24 (two isolates), B44, and B228. FHbp expression levels ranged from 1309 to 8305 (mean fluorescence intensity units). The RR of preimmune sera from subjects was 7% to 27%. RRs increased for all isolates after each vaccine dose. After two doses, RRs ranged from 40% to 93%. After dose 3, RRs were ⩾73% for all isolates (range, 73%-100%). CONCLUSIONS: Each of the representative French outbreak isolates was killed by sera from subjects vaccinated with bivalent rLP2086. Vaccination elicited an immune response with bactericidal activity against these diverse isolates in a large proportion of subjects at risk. These results provide additional support for the licensure strategy of testing MnB strains expressing vaccine-heterologous FHbp variants in hSBAs and further illustrate the breadth of efficacy of this protein-based MnB vaccine.

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.

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.

Neisseria meningitidis Serogroup B Vaccine, Bivalent rLP2086, Induces Broad Serum Bactericidal Activity Against Diverse Invasive Disease Strains Including Outbreak Strains.

BACKGROUND: Bivalent rLP2086 (Trumenba), 1 of 2 meningococcal serogroup B (MnB) vaccines recently approved in the United States for the prevention of MnB disease in individuals 10-25 years of age, is composed of 2 lipidated factor H binding proteins from subfamilies A and B. This study evaluated the breadth of MnB strain coverage elicited by bivalent rLP2086 measured with serum bactericidal assays using human complement (hSBAs). METHODS: hSBA responses to diverse MnB clinical strains circulating in the United States and Europe (n = 23), as well as recent US university outbreak strains (n = 4), were evaluated. Individual prevaccination and postvaccination sera from adolescents and young adults previously enrolled in phase 2 clinical studies of bivalent rLP2086 were assessed. Responders were defined by an hSBA titer ≥1:8, which is more stringent than the accepted correlate of protection (hSBA titer ≥1:4). RESULTS: Baseline hSBA response rates were generally low; robust increases were observed after 2 and 3 doses of bivalent rLP2086, with hSBA responses to all test strains ranging from 31.8% to 100% and 55.6% to 100%, respectively. hSBA responses to strains expressing prevalent subfamily A and B factor H binding protein variants in the United States and Europe, A22 and B24, ranged from 88.0% to 95.0% and 81.0% to 100.0%, respectively, after dose 3. Substantial responses were also observed for recent US outbreak strains. CONCLUSIONS: Bivalent rLP2086 elicits robust hSBA responses to MnB strains expressing 14 factor H binding protein variants representing approximately 80% of MnB invasive isolates and different from vaccine antigens, suggesting that bivalent rLP2086 confers broad protection against diverse MnB disease-causing strains.