The persistence of seroprotective levels of antibodies after vaccination with PreHevbrio, a 3-antigen hepatitis B vaccine

Prevention of hepatitis B virus (HBV) infection by vaccination can potentially eliminate HBV-related diseases. PreHevbrio™/PreHevbri® is a 3-antigen (S, preS1, preS2) HBV vaccine (3A-HBV) recently licensed for adults in the US, EU and Canada. This study evaluated antibody persistence in a subset of fully vaccinated and seroprotected (anti-HBs ≥ 10 mIU/mL) Finnish participants from the phase 3 trial (PROTECT) of 3A-HBV versus single-antigen HBV vaccine (1A-HBV). 465/528 eligible subjects were enrolled (3A-HBV: 244; 1A-HBV: 221). Baseline characteristics were balanced. After 2.5 years, more 3A-HBV subjects remained seroprotected (88.1 % [95 %CI: 84.1,92.2]) versus 1A-HBV (72.4 % [95 %CI: 66.6,78.3)], p < 0.0001) and had higher mean anti-HBs [1382.9 mIU/mL (95 %CI: 1013.8,1751.9) versus 252.6 mIU/mL (95 %CI: 127.5,377.6), p < 0.0001]. In multiple variable logistic regression analysis including age, vaccine, initial vaccine response, sex and BMI, only higher post dose 3 (Day 196) antibody titers significantly reduced the odds of losing seroprotection.

Cost-effectiveness of a 3-antigen versus single-antigen vaccine for the prevention of hepatitis B in adults in the United States

OBJECTIVES

The first 3-antigen hepatitis B vaccine was approved by the United States (US) Food and Drug Administration in November 2021 and was recommended by the Centers for Disease Control and Prevention in 2022. We estimated the cost-effectiveness of this 3-antigen vaccine (PreHevbrio™) relative to the single-antigen vaccine, Engerix-B^TM, to prevent hepatitis B virus (HBV) infection among US adults.

METHODS

A cost-effectiveness model was developed using a combined decision-tree and Markov structure to follow 100,000 adults over their remaining lifetimes after vaccination with either the 3-antigen or single-antigen vaccine. Outcomes from societal and healthcare sector perspectives were calculated for adults aged 18-44, 45-64, and ≥65 years; adults with diabetes; and adults with obesity. Seroprotection rates were obtained from the phase3, head-to-head PROTECT trial (NCT03393754). Incidence, vaccine costs, vaccine adherence rates, direct and indirect costs, utilities, transition probabilities, and mortality were obtained from published sources. Health outcomes and costs (2020USD) were discounted 3% annually and reported by vaccine and population. One-way sensitivity and scenario analyses were conducted.

RESULTS

In the model, the 3-antigen vaccine led to fewer HBV infections, complications, and deaths compared with the single-antigen vaccine in all modeled populations due to higher rates and faster onset of seroprotection. Compared with the single-antigen vaccine, the 3-antigen vaccine had better health outcomes, more quality-adjusted life-years (QALYs), and lower costs in adults aged 18-64 years, adults with diabetes, and adults with obesity (dominant strategy). For adults aged ≥65 years, the 3-antigen vaccine was cost-effective compared with the single-antigen vaccine ($26,237/QALY gained) below common willingness-to-pay thresholds ($50,000-$100,000/QALY gained). In sensitivity analyses, results were sensitive to vaccine cost per dose, incidence, and age at vaccination.

CONCLUSION

The recently approved 3-antigen vaccine is a cost-saving or cost-effective intervention for preventing HBV infection and addressing the long-standing burden of hepatitis B among US adults.

PreHevbrio: the first approved 3-antigen hepatitis B vaccine

INTRODUCTION

Hepatitis B remains a major cause of death and morbidity worldwide. Universal childhood immunization programs have been very successful, but many adults remain unprotected or are not optimally protected. PreHevbrio [Hepatitis B Vaccine (recombinant)] is a highly immunogenic 3-antigen (S/pre-S1/pre-S2) hepatitis B vaccine (3A-HBV) that recently received marketing authorization in the United States (2021), the European Union, United Kingdom (2022 - brand name PreHevbri), and Canada (2022- brand name PreHevbrio) for the prevention of infection caused by all known subtypes of the hepatitis B virus and the delta virus in adults 18 years and older.

AREAS COVERED

This review details the development of 3A-HBV and summarizes the results of the phase 3 clinical trials that support its immunogenicity and safety in adults.

EXPERT OPINION

3A-HBV is highly immunogenic in adults of all ages, including older adults and subgroups that respond sub-optimally to conventional single S-antigen hepatitis B vaccines (1A-HBV), such as those with obesity, type 2 diabetes, and smokers. 3A-HBV provides higher seroprotection rates after each vaccination compared to conventional 1A-HBV vaccines, allowing for more rapid protection. The higher overall immunogenicity is also reflected in more durable seroprotection years after vaccination, as supported by a follow-up study to one of the phase 3 studies.

Exploiting the DNA Damaging Activity of Liposomal Low Dose Cytarabine for Cancer Immunotherapy

Perhaps the greatest limitation for the continually advancing developments in cancer immunotherapy remains the immunosuppressive tumor microenvironment (TME). The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) axis is an emerging immunotherapy target, with the resulting type I interferons and transcription factors acting at several levels in both tumor and immune cells for the generation of adaptive T cell responses. The cGAS-STING axis activation by therapeutic agents that induce DNA damage, such as certain chemotherapies, continues to be reported, highlighting the importance of the interplay of this signaling pathway and the DNA damage response in cancer immunity/immunotherapy. We have developed a multi-targeted mannosylated cationic liposomal immunomodulatory system (DS) which contains low doses of the chemotherapeutic cytarabine (Ara-C). In this work, we show that entrapment of non-cytotoxic doses of Ara-C within the DS improves its ability to induce DNA double strand breaks in human ovarian and colorectal cancer cell lines, as well as in various immune cells. Importantly, for the first time we demonstrate that the DNA damage induced by Ara-C/DS translates into cGAS-STING axis activation. We further demonstrate that Ara-C/DS-mediated DNA damage leads to upregulation of surface expression of immune ligands on cancer cells, coinciding with priming of cytotoxic lymphocytes as assessed using an ex vivo model of peripheral blood mononuclear cells from colorectal cancer patients, as well as an in vitro NK cell model. Overall, the results highlight a broad immunotherapeutic potential for Ara-C/DS by enhancing tumor-directed inflammatory responses.

Evaluation of tumor responses and overall survival in patients with recurrent glioblastoma (GBM) from a phase IIa trial of a CMV vaccine immunotherapeutic candidate (VBI-1901)

2014

Background: Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, which are immunogenic targets in a CMV-based GBM immunotherapeutic. Methods: A total of 20 first-recurrent GBM patients were enrolled, with Karnofsky Performance Status of at least 70, across 2 arms of the Phase IIa extension phase to receive VBI-1901 (a gB/pp65 enveloped virus-like particle [eVLP]) adjuvanted with either GM-CSF (given intradermally) or AS01B (given intramuscularly) (NCT03382977). Patients were vaccinated with VBI-1901 every 4 weeks, with serologic immune-monitoring 2 weeks after each vaccination and surveillance brain MRI scans every 6 weeks. Results: 10 patients (6 women, 4 men) with a median age of 58 (33-67 yrs) were enrolled into the GM-CSF arm and 10 patients (3 women, 7 men) with a median age of 65 (40-67) enrolled into the AS01B arm. The 12-month OS rates for the GM-CSF and AS01B arms were 60% and 70%, respectively; the 18-month OS rate for the GM-CSF arm was 30%, and for the AS01B arm is expected to be 30%-40% (data has not yet matured). Two durable partial responses (locally determined by RANO) have been observed in the GM-CSF arm, with one patient progression-free and on protocol after 2 years with a tumor size reduction of 93% relative to start of treatment. Immunological analyses demonstrate that prolonged, monthly dosing with VBI-1901 does not lead to immunological tolerance. Dynamic boosting and loss in the peripheral blood of CMV-specific CD4 Tem cells after treatment with VBI-1901 formulated with GM-CSF may correlate with tumor responses. Conclusions: The U.S. FDA granted Fast Track Designation to VBI-1901 adjuvanted with GM-CSF in first-recurrent GBM patients, and an expansion of the ongoing trial with this formulation in this patient population, with the addition of randomization with a contemporaneous control arm, is anticipated to begin in H1 2022. Acknowledgement: GlaxoSmithKline Biologicals SA provided the AS01B adjuvant used in this study. Clinical trial information: NCT03382977.

Immunogenicity and Safety of a 3-Antigen Hepatitis B Vaccine vs a Single-Antigen Hepatitis B Vaccine: A Phase 3 Randomized Clinical Trial

IMPORTANCE

There is a need for improved immunogenicity of hepatitis B virus (HBV) vaccines among young adults with risk of infection.

OBJECTIVES

To demonstrate manufacturing equivalence of a 3-antigen (3A) HBV vaccine, evaluate noninferiority of seroprotection rate (SPR) of 3A-HBV vs single-antigen (1A) HBV after 2 and 3 vaccine doses, and compare safety and reactogenicity between 3A-HBV and 1A-HBV vaccines.

DESIGN, SETTING, AND PARTICIPANTS

This phase 3, double-blinded, randomized clinical trial included healthy adults aged 18 to 45 years randomized to 1 of three 3A-HBV groups or 1 control group receiving 1A-HBV. The trial was conducted at 37 community clinics and academic hospitals in Canada, Europe, the United Kingdom, and the United States between December 2017 and October 2019. Participants were followed up for 48 weeks after the first vaccination.

INTERVENTIONS

Intramuscular administration of 3A-HBV (10 μg) or 1A-HBV (20 μg) on days 0, 28, and 168.

MAIN OUTCOMES AND MEASURES

Geometric mean concentration (GMC) of serum hepatitis B surface antibodies (anti-HBs) and proportion of participants achieving seroprotection.

RESULTS

Of 2838 participants, 1638 (57.8%) were women, 2595 (91.5%) were White, and 161 (5.7%) were Black or African American. A total of 712 participants (25.1%) were randomized to the 1A-HBV group and 2126 (74.9%) to 3A-HBV. The mean (SD) age at informed consent was 33.5 (8.0) years. The study demonstrated 3A-HBV lot-to-lot consistency, as the 2-sided 95% CIs for each pairwise comparison for the anti-HBs GMC ratios were within 0.67 and 1.50 (eg, adjusted GMC ratio, lot A vs lot B: 0.82; 95% CI, 0.67-1.00; lot A vs lot C: 0.95; 95% CI, 0.78-1.15; lot B vs lot C: 1.16; 95% CI, 0.95-1.41). The SPR of the pooled 3A-HBV was noninferior to 1A-HBV and higher than 1A-HBV after 2 vaccinations at day 168 (90.4% [95% CI, 89.0%-91.8%] vs 51.6% [95% CI, 47.5%-55.6%]) and 3 vaccinations at day 196 (99.3% [95% CI, 98.7%-99.6%] vs 94.8% [95% CI, 92.7%-96.4%]). The mean GMC of anti-HBs with 3A-HBV was 7.9 times higher after 2 vaccinations at day 168 and 3.5 times higher after 3 vaccinations at day 196 compared with 1A-HBV (after 2 vaccinations, 3A-HBV: GMC, 118.7 mIU/mL; 95% CI, 108.0-129.0 mIU/mL; SE, 1.0 mIU/mL; 1A-HBV: GMC, 15.0 mIU/mL; 95% CI, 12.9-17.5 mIU/mL; SE, 1.0 mIU/mL; after 3 vaccinations, 3A-HBV: GMC, 5442.4 mIU/mL; 95% CI, 4967.0-5963.0 mIU/mL; SE, 1.0 mIU/mL; 1A-HBV: 1567.2 mIU/mL; 95% CI, 1338.0-1834.0 mIU/mL; SE, 1.0 mIU/mL). Rates of local and systemic reactogenicities were higher with 3A-HBV compared with 1A-HBV (local: 1805 of 2124 [85.0%] vs 469 of 712 [65.9%]; systemic: 1445 [68.0%] vs 428 [60.1%]). Vaccine discontinuation due to adverse events (AE) was uncommon, and serious AEs were infrequent, reported in 42 participants (2.0%) and 3 participants (0.4%) in the 3A-HBV and 1A-HBV groups, respectively.

CONCLUSIONS AND RELEVANCE

In this study, consistently higher antibody concentrations and SPRs were found with 3A-HBV after 2 and 3 doses vs 1A-HBV in adults aged 18 to 45 years old. The safety and efficacy of 3A-HBV shows its usefulness for the prevention of hepatitis B in young healthy adults.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT03408730; EU Clinical Trials Number: 2017-001820-22.

Assessment of immunogenicity and safety across two manufacturing lots of a 3-antigen hepatitis B vaccine, Sci-B-Vac®, compared with Engerix-B® in healthy Asian adults: A phase 3 randomized clinical trial

BACKGROUND

Sci-B-Vac®, a 3-antigen hepatitis B vaccine (3A-HBV), contains all three recombinant hepatitis B virus (HBV) envelope proteins (S, pre-S1, and pre-S2). In 2005, 3A-HBV manufacturing transferred facilities (A to B), where it continues to be manufactured.

METHODS

This phase 3, single-blind, randomized study, conducted at one site in Vietnam, compared efficacy and safety among two 3A-HBV lots, lot A and lot B, and a single-antigen hepatitis B vaccine (1A-HBV), Engerix-B®. Primary objective was to demonstrate equivalence at day 210 of two 3A-HBV lots in seroprotection rate (SPR; defined as percentage of participants achieving hepatitis B surface antigen antibody [anti-HBs] titers ≥ 10 mIU/mL). Secondary objectives were assessing immunogenicity at days 180, 210, and 360, and safety of 3A-HBV.

RESULTS

3A-HBV SPR equivalence was demonstrated at day 210 (lot A: 97.3% [95% CI: 92.4%, 99.4%] vs. lot B: 100.0% [97.0%, 100.0%]). Compared to 1A-HBV, lot B SPR was higher at day 180 (98.3% vs. 81.2%; difference: 17.1% [9.7%, 24.6%]) and non-inferior at day 210 (100% vs. 98.3%; difference: 1.7% [-0.6%, 4.1%]). 3A-HBV lot B showed the same SPR after 2 doses (98.3%) as 1A-HBV after 3 doses (98.3%). Adverse events (AEs) were comparable with both 3A-HBV lots (lot A: 68.7% vs. lot B: 54.2%), but higher than 1A-HBV (35.3%). Vaccination-related AEs included transient injection site pain (38.9%), myalgia (9.3%), and fatigue (7.5%). Eight serious AEs were reported (lot A: 3/134 [2.2%]; lot B: 1/134 [0.8%]; 1A-HBV: 4/133 [2.3%]). One serious AE, syncope, was noted as probably related to study vaccine, lot B.

CONCLUSIONS

The two 3A-HBV lots had equivalent immunogenicity, but lot B elicited faster onset of seroprotection and higher anti-HBs titers than both lot A and 1A-HBV in an Asian population. This supports 3A-HBV lot B as an effective choice for HBV vaccination, with a favorable safety profile. ClinicalTrials.gov: NCT04531098.

Evaluation of GM-CSF and AS01B adjuvants in a phase I/IIa trial of a therapeutic CMV vaccine (VBI-1901) against recurrent glioblastoma (GBM)

2047

Background: Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, and are immunogenic targets in a CMV-based GBM vaccine. Methods: We enrolled a total of 20 patients with KPS at least 70 and first recurrence of GBM into 2 arms of the Phase IIa extension of gB/pp65 enveloped virus-like particles (eVLPs) adjuvanted with either GM-CSF given intradermally or with AS01B given intramuscularly (NCT03382977). Patients were vaccinated with VBI-1901 every 4 weeks, with serologic immune-monitoring 2 weeks after each vaccination and surveillance brain MRI scans every 6 weeks. Results: 10 patients (6 women, 4 men) with a median age of 58 (33-67 yrs) were enrolled into the GM-CSF arm and 10 patients (3 women, 7 men) with a median age of 65 (40-67) enrolled into the AS01B arm. Disease control rates of 40% and 50% were observed in the GM-CSF and AS01B arms, respectively, with 2 sustained PRs in the GM-CSF arm. The 6-month OS rate for the GM-CSF arm is 80% and is estimated to be comparable for the AS01B arm. CMV-specific CD4+ effector memory T cells may correlate with tumor responses in both arms of the study, with AS01B boosting higher frequencies of these cells regardless of baseline CD4/CD8 ratio. Conclusions: These encouraging results from both arms of the trial justify further clinical evaluation in a randomized, controlled trial expected to begin later in 2021. Clinical trial information: NCT03382977.

Immunogenicity and safety of a tri-antigenic versus a mono-antigenic hepatitis B vaccine in adults (PROTECT): a randomised, double-blind, phase 3 trial

BACKGROUND

The seroprotection rate (SPR) of hepatitis B vaccination in adults is suboptimal. The aim of this study was to compare the SPR of a tri-antigenic hepatitis B vaccine (TAV), with a mono-antigenic vaccine (MAV) in adults of all ages.

METHODS

This was a multicentre, double-blind, phase 3, randomised controlled trial (PROTECT) comparing the immunogenicity and safety of TAV with MAV in 28 community and hospital sites in the USA, Finland, Canada, and Belgium. Adults (aged ≥18 years) seronegative for hepatitis B virus (HBV), including those with well-controlled common chronic conditions, were randomly assigned (1:1) and stratified by study centre and age according to a web-based permuted blocked randomisation. Participants received either TAV or MAV which were administered as an intramuscular dose (1 mL) of TAV (10 μg; Sci-B-Vac, VBI Vaccines [SciVac, Rehovot, Israel]) or MAV (20 μg; Engerix-B [GlaxoSmithKline Biologicals, Rixensart, Belgium]) on days 0, 28, and 168 with six study visits and 24 weeks of follow-up after the third vaccination. Participants, investigators, and those assessing outcomes were masked to group assignment. The co-primary outcomes were to show non-inferiority of the SPRs 4 weeks after the third vaccination with TAV versus MAV in adults aged 18 years and older, as well as superiority in adults aged 45 years and older. SPR was defined as the percentage of participants attaining anti-HBs titres of 10 mIU/mL or higher. Non-inferiority of TAV to MAV was concluded if the lower limit of the 95% CI for the between-group difference was greater than -5%. Non-inferiority was assessed in the per-protocol set of participants (aged ≥18 years) and superiority was assessed in all participants (aged ≥45 years) who received at least one vaccination and had at least one evaluable immunogenicity sample after baseline (full analysis set). Safety analyses were a secondary outcome and included all participants who received at least one injection. This trial is registered at Clinicaltrials.gov (NCT03393754) and EudraCT (2017-001819-36) and is closed to new participants.

FINDINGS

Between Dec 13, 2017, and April 8, 2019, 1607 participants (796 allocated to TAV and 811 allocated to MAV) were randomly assigned and distributed across age cohorts of 18-44 years (299 of 1607; 18·6%), 45-64 years (716 of 1607; 44·6%), and 65 years and older (592 of 1607; 36·8%). In participants aged 18 years and older, SPR was 91·4% (656 of 718) in the TAV group versus 76·5% (553 of 723) in the MAV group (difference 14·9%, 95% CI 11·2-18·6), showing non-inferiority in the per-protocol set. In participants aged 45 years and older, SPR was 89·4% (559 of 625) in the TAV group versus 73·1% (458 of 627) in the MAV group (difference 16·4%, 95% CI 12·2-20·7), showing superiority in the full analysis set. TAV was associated with higher rates of mild or moderate injection site pain (63·2% [503 of 796] in TAV vs 36·3% [294 of 811] in MAV), tenderness (60·8% [484 of 796] in TAV vs 34·8% [282 of 811] in MAV), and myalgia (34·7% [276 of 796] vs 24·3% [197 of 811] in MAV). Otherwise, the safety profile of TAV was similar to that of MAV.

INTERPRETATION

The safety and efficacy of TAV shows its usefulness for the prevention of HBV infection in adults, including those with stable and controlled chronic conditions.

FUNDING

VBI Vaccines.

8. Higher hepatitis B antibody titres induced in all adults vaccinated with a tri-antigenic hepatitis B (HBV) vaccine, compared to a mono-antigenic HBV vaccine: results from two pivotal phase 3 double-blind, randomized studies (PROTECT and CONSTANT)

Background

More than 2 billion individuals worldwide have evidence of past or current hepatitis B virus (HBV) infection, emphasizing the importance of awareness and need for elimination of HBV infection. Effective vaccination, defined as the induction of protective anti-HBs titres, is a key component of those elimination plans. Magnitude of the immune response to HBV vaccines can be measured by serum levels of anti-HBs, whose persistence and durability is believed to be dependent upon the peak antibody levels reached after completion of vaccinations.

CONSTANT and PROTECT: High Hepatitis B antibody titres after vaccination

Methods

In two phase 3, head-to-head studies of immunogenicity and safety of a tri-antigenic HBV vaccine (TAV) containing 10 µg of full-length HBs (pre-S1 + pre-S2 + S antigens) and a mono-antigenic HBV vaccine (MAV) containing 20 µg of small HBs antigen, subjects were vaccinated at months 0, 1 and 6 with safety follow-up for at least 6 months after the 3^rd vaccination. PROTECT, which enrolled 1607 adults age ≥18, demonstrated non-inferiority of seroprotection rates (SPR, defined as the % of participants achieving anti-HBs titres ≥10 mIU/mL) of TAV vs. MAV in adults age ≥ 18 and superiority of SPR in adults age ≥ 45. CONSTANT, which enrolled 2838 adults age 18–45 demonstrated manufacturing equivalence of 3 lots of TAV. In both studies, anti-HBs titres were measured across timepoints and safety was assessed.

Results

In CONSTANT, at day 168 after two doses, mean anti-HBs titers (mIU/mL) induced across the 3 lots of TAV were > 7.5x those induced with MAV [113–124 vs. 15]. At day 196, after the 3^rd dose, mean anti-HBs titers induced with TAV remained substantially higher than those induced with MAV [4855–5979 vs. 1526] (Fig A). In PROTECT, anti-HBs titers were 6x higher in all subjects ≥ 18 year at day 196 [1148 vs. 193] with TAV and 5-8x higher in key subgroups compared to MAV, regardless of age, BMI, or diabetic status (Fig B). Adverse events were well-balanced and consistent with known vaccine safety profiles.

Conclusion

In the two pivotal phase 3 studies, TAV demonstrated its ability to rapidly elicit higher anti-HBs titres compared to MAV, in all study subject populations, reflecting the very strong immune response to TAV, which may be an important predictor of the persistence and durability of seroprotection.

Disclosures

Joanne M. Langley, MD, GSK group of companies (Research Grant or Support)Immunivaccines Inc (Scientific Research Study Investigator, Research Grant or Support)Janssen (Research Grant or Support)Pfizer (Research Grant or Support)Symvivo (Scientific Research Study Investigator, Research Grant or Support)VBI Vaccines (Research Grant or Support) Nathalie Machluf, PhD, VBI Vaccines Inc. (Employee) Johanna Spaans, BSc, MSc, VBI Vaccines Inc (Employee) Dave Anderson, PhD, VBI Vaccines (Employee, Shareholder) Vlad Popovic, MD, VBI Vaccines, Inc. (Employee, Shareholder) Francisco Diaz-Mitoma, MD, VBI Vaccines, Inc. (Shareholder, Independent Contractor)

CTIM-07. IDENTIFICATION OF A BASELINE BIOMARKER ASSOCIATED WITH TUMOR RESPONSES IN A PHASE I/IIa TRIAL OF A THERAPEUTIC CMV VACCINE AGAINST RECURRENT GLIOBLASTOMA (GBM)

Cytomegalovirus (CMV) antigens have been reported in over 90% of GBM tumors. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, and are immunogenic targets in a CMV-based GBM vaccine. We enrolled 10 patients (6 women, 4 men) with KPS at least 70 and first recurrence of GBM to a trial (Phase IIa extension) of gB/pp65 enveloped virus-like particles (eVLPs) with GM-CSF. Intradermal vaccination was administered every 4 weeks, with serologic immune-monitoring 2 weeks after each vaccination and surveillance brain MRI scans every 6 weeks. Median age was 59 years (range 33–67). Among 8 response-evaluable patients, we observed 1 SD and 1 PR. Among all patients treated on phase I and II (n=26), a normal baseline ratio of CD4/CD8 T cells in peripheral blood predicted response (n=6). Other baseline peripheral blood markers did not correlate with efficacy, including total white blood cell, lymphocyte percentage, and absolute lymphocyte count. During treatment, the peripheral blood of responders demonstrated dynamic losses followed by subsequent reappearance and expansion of CMV-specific CD4+ effector memory T cells. Based on these encouraging results, a new arm is enrolling subjects combining gB/pp65 eVLPs (at the same dose) formulated with adjuvant intramuscular AS01B and results will be presented.

Efficacy and Safety of a 3-Antigen (Pre-S1/Pre-S2/S) Hepatitis B Vaccine: Results of a Phase 3 randomized clinical trial in the Russian Federation

Background

This study compares the immunogenicity and safety of a 3-antigen (S/pre-S1/pre-S2) hepatitis B (HepB) vaccine (3AV), to a single antigen vaccine (1AV) in adults to support the registration of 3AV in Russia.

Methods

We conducted a randomized, double-blind, comparative study of 3-dose regimens of 3AV (10 μg) and 1AV (20 µg) in adults aged 18–45 years. We evaluated immunogenicity based on hepatitis B surface (HBs) antibody titers at days 1, 28, 90, 180, and 210, adverse and serious adverse events (SAEs) to study day 210. The primary outcome was based on the difference in rates of seroconversion at day 210 (lower bound 95% confidence interval [CI]: > − 4%). Secondary outcomes were seroprotection rates (SPR), defined as anti-HBs ≥10 mIU/mL and anti-HBs geometric mean concentration (GMC).

Results

Rate of seroconversion in 3AV (100%) was noninferior to 1AV (97.9%) at study day 210 (difference: 2.1%, 95% CI: −2.0, 6.3%]) but significantly higher at study day 28. SPR at study day 210 was >97% in both arms. Anti-HBs titers were significantly higher at study days 90 (P = .001) and 180 (P = .0001) with 3AV. Sex, age, and body mass index (BMI) had no impact on anti-HBs titers. The rates of local reactions related to vaccination were similar between vaccine arms (3AV vs 1AV) after the first (30% vs 18.8%, P = .15), second (20.0% vs 14.6%, P = .33), and third vaccination (14.9% vs 23.4%, P = .22). No SAEs were reported.

Conclusions

3AV was noninferior to 1AV. 3AV induced high SPR, and there were no safety concerns.

Clinical Trials Registration. NCT04209400.

Abstract 6538: CMV-specific immuno-dysregulation in recurrent glioblastoma patients can be overcome with therapeutic vaccination which is associated with tumor response and overall survival benefits in a Phase I/IIA study

Numerous independent laboratories using several techniques have demonstrated cytomegalovirus (CMV) antigens in over 90% of glioblastoma (GBM) tumors. We initiated a phase I/IIA multicenter study designed to demonstrate safety and determine the most immunogenic dose of an enveloped virus-like particle (eVLP) vaccine expressing the CMV gB and pp65 antigens for treatment of recurrent GBM patients. In Part A of the trial, 6 patients in each of 3 different antigen dose cohorts were vaccinated monthly and followed until tumor progression, with PBMCs collected 2 weeks after each vaccination. Surprisingly, only 7/18 patients enrolled in Part A of the trial had baseline CMV-specific antibody (Ab) titers. This was unexpected given the documented high prevalence of CMV antigens in GBM tumor samples as well as epidemiological data demonstrating much higher CMV Ab seropositive rates in otherwise healthy individuals of a comparable age. In the low dose cohort, 4/6 patients had baseline CMV Ab titers. Of these 4 patients,vaccination boosted strong T cell responses in 2 patients (based on IFN-γ ELISPOT against CMV gB and pp65 antigens). Vaccination did not boost T-cell responses in the CMV Ab-negative patients. In the intermediate dose cohort, among 4 evaluable patients, T cell responses were robustly boosted in the only patient with a baseline CMV Ab titer. In marked contrast, the T-cell responses in the high dose cohort were boosted in 3/5 evaluable patients, all of which were CMV Ab seronegative at baseline. Moreover, the T-cell responses correlated with tumor responses (stable disease based on 2 or more stable MRI scans) as well as improved PFS and 6 month OS relative to vaccine non-responders. To further understand the apparent disconnect between baseline CMV Ab titers and vaccine-mediated impact on tumor and clinical responses, we developed a more sensitive flow cytometry-based assay which evaluated proliferating (Ki-67-positive) gB- and pp65-specific T cells within naïve, central memory (CD45RA-CCR7+) or effector memory (CD45RA-CCR7-) subsets. Among 2/3 tested vaccine responders evaluated thus far in the high dose cohort that were CMV Ab negative at baseline, high frequencies of effector memory cells (~2% total CD3+CD4+ T cells) against both the CMV pp65 and gB antigens were detected at baseline. Collectively, these data suggest that CMV-specific immune dysregulation exists in a substantial number of rGBM patients, which can be overcome with the appropriate dose of a CMV vaccine immunotherapeutic. Importantly, vaccine-mediated boosting of CMV immunity correlates with improved tumor response and clinical outcomes and warrants further confirmation.

Citation Format: Tamara Berthoud, Felicia Deonarine, Spenser Ng Cheong Chung, Catalina Soare, Francisco Diaz-Mitoma, David E. Anderson. CMV-specific immuno-dysregulation in recurrent glioblastoma patients can be overcome with therapeutic vaccination which is associated with tumor response and overall survival benefits in a Phase I/IIA study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6538.

ATIM-26. INTERIM RESULTS OF THE EXTENSION PHASE OF A PHASE I/IIA TRIAL OF A THERAPEUTIC CMV VACCINE AGAINST RECURRENT GLIOBLASTOMA (GBM)

Cytomegalovirus (CMV) antigens have been reported in over 90% of GBM tumors. CD4+and CD8+T cells are most frequently directed against the gB and pp65 antigens, respectively, and are immunogenic targets in a CMV-based GBM vaccine. We have initiated a phase I/IIa clinical trial for patients with recurrent GBM using gB/pp65 enveloped virus-like particles (eVLPs) formulated with GM-CSF and administered intradermally. In phase I, eligible patients were age 18–70 with Karnofsky Performance Status at least 70, normal end-organ function, on stable or decreasing corticosteroids of at most 4mg dexamethasone (or equivalent), with recurrent GBM following any standard initial therapy and any number of recurrences of any size. Patients were vaccinated monthly until tumor progression, with immune-monitoring performed 2 weeks after each vaccination and MRI exams every 6 weeks. The primary endpoint was safety/tolerability and secondarily to assess immunogenicity. Three vaccine doses (0.4µg, 2µg, and 10µg pp65) were evaluated with 6 patients in each cohort, and the DSMB identified no DLTs or safety concerns with any of the doses. The highest 10µg dose was chosen for the Phase IIa extension phase of the trial based on stable disease (3 months or longer) observed in 3/6 patients, which correlated with vaccine-induced IFN-γ-secreting T cell responses against CMV. Enrollment in phase IIa of the trial, which is designed to explore initial potential efficacy signals in an additional 10 patients that receive the optimal 10µg dose of vaccine, is expected in June 2019 and includes the additional requirements of unifocal, measurable enhancing tumor 1–3 cm across at first recurrence and no prior immunotherapy. Patients will be vaccinated monthly until clinical progression. Tumor responses and associated immunological biomarkers will be presented, and are expected to include initial data for all 10 patients.

LB13. Trivalent Hepatitis B (HepB) Vaccine Yields Superior Seroprotection Rates in Adults: Results from the Phase 3 Double-Blind, Randomized Study Comparing Immunogenicity and Safety of a 3-Dose Regimen of Sci-B-Vac™ and Engerix B® (PROTECT)

Background

Many adults fail to achieve seroprotection after receiving 3 doses of monovalent HepB vaccines such as Engerix-B® and the response decreases with age and with common co-morbidities. Sci-B-Vac™ is a trivalent HepB vaccine produced in mammalian cells, adjuvanted with aluminum hydroxide, which in addition to small S antigen, contains preS1 and preS2 antigens expressing highly immunogenic T- and B-cell epitopes that may enhance seroprotection rates (SPR) in adults.

Methods

In a multicentre study, the immunogenicity of 10 µg dose of Sci-B-Vac™ was compared with a 20-µg dose of Engerix-B® given at days 0, 28, and 168 (NCT03393754). Randomization was stratified by study center and age (18–44, 45–64, ≥65 years). Immunogenicity, including SPR (% subjects with anti-HBs levels ≥10 mIU/mL), and safety outcomes were followed to Day 336. The co-primary objectives were (1) non-inferiority in adults ≥18 years and (2) superiority in adults ≥45 years of SPR, 4 weeks after the third dose.

Results

Of 1,607 randomized subjects, 42.3% were from United States, 41.6% EU, and 16.1% Canada. Males (38.5%) and females (61.5%) were enrolled to 18–44 (18.6%), 45–64 (44.6%), and ≥ 65 year (36.8%) age groups. Both co-primary endpoints were met. In the non-inferiority analysis, SPR in Sci-B-Vac™ recipients aged ≥18 years was 91.4% vs. 76.5% for Engerix-B®; SPR difference: 14.9%; 95% confidence interval (CI) [11.2%, 18.6%]. Superiority analysis showed that SPR in Sci-B-Vac™ recipients aged ≥45 years was 89.4% vs. 73.1% for Engerix-B®—SPR difference: 16.4%; 95% CI [12.2%, 20.7%] (figure). Significantly higher SPR for Sci-B-Vac™ vs. Engerix-B® was noted in subgroups (gender, BMI, diabetes, smoking and particularly age—SPR difference for 45–64 (14.7% [9.8–19.8%]) and ≥ 65 (18.9% [11.6–26.1%]) years. No major safety signals were observed; solicited and unsolicited adverse events were consistent with the known vaccine safety profiles.

Conclusion

Sci-B-Vac™ met immunogenicity endpoints for non-inferiority in adults aged ≥ 8 years and was superior in adults aged ≥45 years, compared with the monovalent vaccine, Engerix-B®. Sci-B-Vac™ SPR was higher compared with Engerix-B® in key subgroups. No safety signals were observed and safety and tolerability were consistent with the known profile of Sci-B-Vac™.

Disclosures

Timo Vesikari, MD, VBI (Grant/Research Support, I have received funding from VBI to carry out the reported clinical trial in Finland), Joanne M. Langley, MD, VBI Vaccines (Grant/Research Support), Johanna Spaans, BSc, MSc, VBI Vaccines (Employee), Nathalie Machluf, PhD, SciVac Ltd. (Employee), Dave Anderson, PhD, VBI Vaccines, Inc. (Employee, Shareholder), Vlad Popovic, MD, VBI Vaccines (Employee), Francisco Diaz-Mitoma, MD, VBI Vaccines, Inc. (Consultant, Shareholder, Independent Contractor). Other Authors: No reported disclosures.

Interim results of a phase I/IIa trial of a therapeutic CMV vaccine against recurrent glioblastoma (GBM)

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Background: Cytomegalovirus (CMV) antigens have been reported in over 90% of GBM tumors. CD4+and CD8+T cells are most frequently directed against the gB and pp65 antigens, respectively, and are immunogenic targets in a CMV-based GBM vaccine. Methods: We have initiated a phase I/IIa clinical trial for patients with recurrent GBM using gB/pp65 enveloped virus-like particles (eVLPs) formulated with GM-CSF and administered intradermally. Subjects are vaccinated monthly until tumor progression, with immunomonitoring performed 2 weeks after each vaccination and MRI exams every 6 weeks. In phase I, eligible patients were age 18-70 with Karnofsky Performance Status at least 70, normal end-organ function, on stable or decreasing corticosteroids of at most 4mg dexamethasone (or equivalent), with recurrent GBM following any standard initial therapy and any number of recurrences. The primary endpoint was safety/tolerability and secondarily to assess immunogenicity. Three vaccine doses (0.4µg, 2µg, and 10µg pp65) were evaluated with 6 subjects in each cohort and DSMB safety review of the first 3 subjects in each cohort prior to enrolling additional subjects. Results: The DSMB identified no DLTs or safety concerns with any of the doses. Grade 2, 3 or 4 AEs occurred in 66%, 22% and 11% of participants, respectively, but were not related to vaccine administration. Twelve men and 6 women were enrolled with a median age 54 (range 39-66). Prior therapies included radiotherapy, temozolomide, and nivolumab. Immunological analyses demonstrate robust boosting of CMV-specific antibody titers and T cell responses against both gB and pp65 antigens in some but not all subjects, across all dose cohorts. Boosting of IFN-gsecreting T cells (measured by ELISPOT) exceeded the assay threshold for several subjects. Stable disease by MRI of 3 months or greater has been observed in 2 subjects in the high dose cohort and 1 subject in the low dose cohort and may correlate with vaccine response. Conclusions: The phase IIa extension phase of the trial planned to begin in Q2 2019 is designed to explore efficacy in an additional 10 subjects that will receive the optimal vaccine dose and includes the additional requirements of unifocal, measurable enhancing tumor 1-3 cm across at first recurrence and no prior immunotherapy. Clinical trial information: NCT03382977.

LB18. An Enveloped Virus-like Particle (eVLP) Cytomegalovirus (CMV) Vaccine Is Immunogenic and Safe: Results of a First-in-Humans Study

Background

CMV is the most common cause of congenital infection and may result in permanent neurodevelopmental injury including vision and hearing loss. A vaccine to prevent transmission of CMV during pregnancy or to immunocompromised persons is a public health priority. Neutralizing antibodies (nAb) to the CMV envelope glycoprotein B (gB) in natural infection are thought to confer protection, but some vaccine candidates based on this protein alone have been insufficiently immunogenic. In this FiH dose-ranging, controlled, observer-blinded study the safety and immunogenicity of an eVLP expressing the ectodomain of gB fused to transmembrane and cytoplasmic domains of the vesicular stomatitis virus G protein (gB-G) was evaluated.

Method

Healthy CMV-seronegative 18–40 year olds at three sites in Canada (Vancouver, Montreal, Halifax) were randomized to one of four dose formulations (0.5 µg, 1 µg, or 2 µg gB content with Alum) or 1 µg gB without Alum, or placebo given on days 0, 56, and 168. Outcome measures were solicited and unsolicited adverse events (AE), severe AE, gB binding antibody titers and avidity assessment, and nAb to CMV infection of fibroblast and epithelial cells. A Data Safety Monitoring Board was in place.

Result

Among 128 participants, the most common solicited local and general AEs were pain and headache, respectively. No SAEs or withdrawals occurred. A dose-dependent boosting of nAb titers was observed after doses 2 and 3, with the highest titers in the Alum-adjuvanted 2.0 µg dose recipients. Fibroblast cell nAb were seen in 100% of 2.0 µg dose recipients, and epithelial cell nAb in 31%. Epithelial cell nAb was correlated with higher geometric mean gB binding titers, and there was a correlation between fibroblast and epithelial cell nAb titers.

Conclusion

An eVLP CMV vaccine was immunogenic at very low doses in healthy seronegative adults and no safety signals were seen. Alum adjuvantation increased immunogenicity as did higher antigen content and multiple doses. This phase 1 trial supports further development of this eVLP CMV vaccine candidate.

ClinicalTrials.gov NCT02826798

Disclosures

S. Gantt, VBI Vaccines: Investigator, No direct financial benefit—company provided institutional support for clinical trial. C. Quach, VBI Vaccines: Investigator, No direct financial benefit—company provided institutional support for clinical trial. D. E. Anderson, VBI Vaccines: Employee and Shareholder, Salary. F. Diaz-Mitoma, VBI Vaccines: Consultant and Shareholder, Salary. J. Langley, VBI Vaccines: Investigator, No direct financial benefit—company provided institutional support for clinical trial.

Use of CMV gB/pp65 eVLPs to harness the immunogenicity of foreign viral antigens to target solid tumors

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Background: Human cytomegalovirus (CMV) is a ubiquitous, generally asymptomatic virus that is present in over 90% of GBM and breast cancer tumors which have comparatively low mutational burdens and predicted neoantigens relative to melanoma or lung cancer. Memory CD4+ and CD8+T cells are most frequently directed against the gB and pp65 antigens, respectively. Thus, CMV gB and pp65 represent highly immunogenic “foreign” antigen components of a vaccine against GBM and breast cancer. Methods: Enveloped virus-like particles (eVLPs) are produced after transfection of HEK 293 cells with a plasmid encoding murine leukemia virus Gag plasmid fused in-frame with CMV pp65 antigen, which gives rise to particles. Co-transfected CMV gB plasmid enables particles budding from the cell surface to incorporate the gB protein into the lipid bilayer. Surface expression of gB and internal expression of pp65 have been confirmed by CryoEM and immunogold labelling. Production and purification of multiple batches at a GMP-compliant manufacturer has demonstrated consistent purity and yields that meet regulatory requirements. Results: eVLPs restimulate IFN-g secreting CD4+ and CD8+ T cells in ex vivo PBMCs from healthy subjects (n=8) at mean frequencies of 0.27% and 1.28%, respectively. eVLP formulation with GM-CSF augments IFN-g and CCL3 secretion in stimulated PBMCs from healthy subjects (n=5), GBM patients (n=5), and breast cancer (n=1) patients to comparable levels. This vaccine candidate also induces de novo CD4+ and CD8+responses in mice. The vaccine induces high titer antibody responses against CMV gB, and the potential for ADCC activity against gB-expressing GBM tumor cells is currently being investigated. Conclusions: CMV gB/pp65 eVLPs address several shortcomings of past theraeputic vaccines, including: 1) the poor immunogenicity of "self" tumor-associated antigens, 2) failure to induce robust CD4+ responses that support CD8+ tumor-specific responses, 3) inclusion of only one or a few epitopes that rapidly encourage tumor cell immunoselection of variants that no longer express the target(s). An IND submission to FDA for a phase I/IIa trial in GBM patients is planned for H1 2017.

Oral Famciclovir for the Suppression of Recurrent Genital Herpes: The Combined Data from Two Randomized Controlled Trials

Background:

Genital herpes is a very common sexually transmitted disease. Safe and effective therapies are needed for patients with frequent recurrences.

Objective:

The aim of our study was to determine the efficacy and safety of famciclovir for suppression of herpes simplex virus (HSV) infection in patients with a history of clinically diagnosed recurrent genital HSV infection.

Method:

An analysis was conducted of the combined data from two randomized, double-blind, placebo-controlled studies of 52 weeks' duration involving a total of 469 patients (201 men, 268 women) from 47 university, hospital, or private referral centers in Europe and North America. The patients were 18 years or older with a history of six or more episodes of genital herpes during 12 of the 24 months prior to study entry and were not receiving suppressive therapy. They were randomized to receive oral famciclovir 250 mg twice daily or placebo for 52 weeks. The primary outcome measures were (1) the proportion of patients who remained free from clinical HSV recurrences, confirmed by viral culture, for at least 6 months after the start of study medication; (2) the time to first clinically confirmed lesional episode; and (3) the frequency of adverse events.

Results:

A significantly greater proportion of famciclovir-treated patients (151/191, 79%) were free from HSV recurrences at 6 months compared with placebo recipients (48/184, 26%) ( p < 0.001); efficacy was maintained at 12 months. The median time to the first clinically confirmed lesional episode was significantly prolonged for famciclovir recipients (more than one year) compared with placebo recipients (59 days; p < 0.0001). Famciclovir was well tolerated, with an adverse-experience profile comparable with placebo.

Conclusions:

Oral famciclovir 250 mg twice daily is an effective, well-tolerated treatment for the suppression of genital HSV infection in patients with frequent recurrences.

Antécédents et objectifs:

L'herpès génital est une maladie sexuellement transmissible très fréquente. Les patients qui présentent un niveau élevé de récurrence doivent recevoir des traitements efficaces et sécuritaires. La présente analyse vise l'établissement de l'efficacité et de l'innocuité du famciclovir, un antiviral destiné à supprimer l'infection au virus de l'herpès simplex (HSV) chez les patients ayant des antécédents cliniques d'infections génitales récidivantes au HSV.

Méthodes:

Analyse des données combinées de deux études randomisées, a double insu, contrôlées centre placebo. Les études étaient d'une durée de 52 semaines, et portaient sur 469 patients (201 hommes et 268 femmes) provenant de 47 universités, hôpitaux et centres privés en Europe et en Amérique du Nord. Les patients avaient au moins 18 ans et ont présenté des antécédents d'au moins six épisodes d'herpès génital au cours des 12 à 24 mois précédant l'étude. Ils ne suivaient aucun traitement suppressif. Durant 52 semaines, ils ont reçu soit 250 mg de famciclovir deux fois par jour, soft un placebo. Les principales mesures des résultats étaient: 1) la proportion de patients qui ne présentent pas une récidive clinique de HSV confirmée par culture virale, pendant au moins 6 mois après le début du traitement; 2) l'intervalle de temps avant le premier épisode cliniquement confirmé; et 3) la fréquence des événements indésirables.

Résultats:

Une proportion marquée de patients recevant le famciclovir (151/191, 79%) n'ont pas eu une récidive d'herpès au 6e mois du traitement, comparativement aux patients recevant le placebo (48/184, 26%) ( p < 0.001); l'efficacité s'est maintenue au 12e mois. Le temps moyen avant le premier épisode cliniquement confirmé a été considérablement plus long pour les patients traités au famciclovir (plus d'un an) que pour les patients au placebo (59 jours; p < 0.0001). Le famciclovir était bien toiéré et le profil des événements indésirables était comparable à celui du placebo.

Conclusions:

Une dose de 250 mg de famciclovir oral, prise deux fois par jour, représente un traitement efficace et bien toléré pour la suppression de l'infection au virus HSV de l'herpès génital, lorsque les patients ont des récidives fréquentes.

Evaluating the immunogenicity of an intranasal vaccine against nicotine in mice using the Adjuvant Finlay Proteoliposome (AFPL1)

Tobacco smoking is recognized as a global pandemic resulting in 6 million deaths per year. Despite a variety of anti-smoking products available to aid with tobacco cessation, the majority of people who attempt to quit smoking relapse within 6 months due to the addictive nature of nicotine. An immunotherapy approach could offer a promising treatment option by inducing a potent selective antibody response against nicotine in order to block its distribution to the brain and its addictive effects in the central nervous system. Our nicotine vaccine candidate was administered intranasally using the Neisseria meningitidis serogroup B Adjuvant Finlay Proteoliposome 1 (AFPL1) as a part of the delivery system. This system was designed to generate a robust immune response by stimulating IL-1β production through Toll-like receptor 4 (TLR4), a potent mechanism for mucosal immunity. The vaccine induced high antibody titers in mice sera in addition to inducing mucosal antibodies. The efficacy of our vaccine was demonstrated using in vivo challenge experiments with radioactive [³H]-nicotine, followed by an analysis of nicotine distribution in the lung, liver, blood and brain. Our results were encouraging as the nicotine concentration in the brain tissue of mice vaccinated with our candidate vaccine was four times lower than in non-vaccinated controls; suggesting that the anti-nicotine antibodies were able to block nicotine from crossing the blood brain barrier. In summary, we have developed a novel nicotine vaccine for the treatment of tobacco addiction by intranasal administration and also demonstrated that the AFPL1 can be used as a potential adjuvant for this vaccine design.

False Negative Results in Clostridium difficile Testing

Background

Accurate diagnosis of Clostridium difficile infection (CDI) is paramount for patient management. The wrong diagnosis places patients at risk, delays treatment, and/ or contributes to transmission of infection in the healthcare setting. Although amplification of the toxin B gene by polymerase chain reaction (PCR) is a sensitive method for detecting toxigenic C. difficile, false negative results still occur and could impact the diagnosis and treatment of this infection.

Methods

This study investigated 48 patients that tested negative for toxigenic C. difficile via GeneXpert C. difficile epi test, while simultaneously testing positive for toxigenic C. difficile via stool culture. Fifty discrepant samples were collected over a 15-month period and all C. difficile isolates were characterized by ribotype. Patient charts were reviewed to assess whether discrepant results impacted the treatment course or clinical outcome of affected patients.

Results

Fifty samples of a total of 2308 samples tested in an acute healthcare facility over a 15-month period had negative PCR and positive stool culture for toxigenic C. difficile. C. difficile isolated from the discrepant samples resulted in diverse ribotyping patterns suggesting they were derived from different strains. The samples belonged to patients who were distributed evenly between age groups and wards in the hospital. In the majority of cases, the false negative C. difficile test results did not seem to impact the clinical outcome in these patients.

Conclusions

The PCR limit of detection may impact the results of molecular methods for C. difficile detection. Both clinical and analytical sensitivity of C. difficile tests should be considered when deciding which diagnostic assay to use, and clinical correlates should be examined carefully before excluding CDI as a cause of disease.

Expedient synthesis of functional single-component glycoliposomes using thiol-yne chemistry

The preparation of a set of eight unprecedented amphiphilic neoglycolipids forming liposome nanoparticles is reported. The small library was readily obtained from various peracetylated propargyl glycopyranosides via efficient radical-initiated thiol-yne (TYC) coupling reactions using alkanethiols of different chain lengths. In addition, using sequential thiol-yne, both the nature and positioning of the lipophilic alkanethiols could be varied at will, thus providing unparalleled variability within the glycolipid structures. Two different classes of self-assemblies were prepared from the new neoglycolipids. First, liposomes of 150-300 nm were obtained by solvent injection of their ethanol or tetrahydrofuran (THF) solution in water. The resulting structures were analyzed by dynamic light scattering (DLS) and atomic force microscopy (AFM). The mannosylated lipid nanoparticle (compound 14) showed good stability in water. Alternatively, giant soft unilamellar vesicles were also obtained by film hydration and visualized by differential interference contrast microscopy (DIC). Incorporation of a hydrophobic dye to the solution prior to evaporation allowed visualization by confocal microscopy. Finally, the biological functions of the newly formed glycolipid vesicles were evaluated by multivalent carbohydrate-protein binding interactions using concanavalin A (ConA). Agglutination assays and the binding of glycolipid by dendritic cells (DCs) resulted in an increase in DCs immunostimulatory potential. Importantly, we did not see changes in cells viability at tested doses. This study provides a new, simple and highly efficient methodology to produce novel glyconanoparticle candidate as model in development of vaccine adjuvant and drug delivery system.

Next Steps in Primary Prevention of Coronary Heart Disease: Rationale for and Design of the ECAD Trial

Atherosclerotic cardiovascular disease (ASCVD) events, including coronary heart disease and stroke, are the most frequent cause of death and major disability in the world. Current American College of Cardiology/American Heart Association primary prevention guidelines are mainly on the basis of randomized controlled trials of statin-based low-density lipoprotein cholesterol (LDL-C)-lowering therapy for primary prevention of ASCVD events. Despite the clear demonstration of statin-based LDL-C lowering, substantial 10-year and lifetime risks of incident ASCVD continue. Although the 10-year risk is low in young and middle-aged adults who would not be treated according to current guidelines, they ultimately account for most incident ASCVD. If statin-based LDL-C lowering were initiated in them at an age before complex coronary plaques are common in the population, a substantial reduction in lifetime risk of incident coronary heart disease might be achieved. We examine this hypothesis and introduce the design of a currently recruiting trial to address it. (Eliminate Coronary Artery Disease [ECAD]; NCT02245087).

Further Evidence that Human Endogenous Retrovirus K102 is a Replication Competent Foamy Virus that may Antagonize HIV-1 Replication

Objective:

The goals of the research were to determine if a foamy effect on macrophages was due to human endogenous retrovirus K102 (HERV-K102) replication, and to further address its potential significance in HIV-1 infection.

Methods:

An RT-PCR HERV-K HML-2 pol method was used to screen the unknown HERV, and isolated bands were sent for sequencing. Confirmation of RNA expression was performed by a real time quantitative PCR (qPCR) pol ddCt method. Rabbit antibodies to Env peptides were used to assess expression by immunohistology and processing of Env by western blots. A qPCR pol ddCt method to ascertain genomic copy number was performed on genomic DNA isolated from plasma comparing HIV-1 exposed seronegative (HESN) commercial sex workers (CSW) to normal controls and contrasted with HIV-1 patients.

Results:

HERV-K102 expression, particle production and replication were associated with foamy macrophage generation in the cultures of cord blood mononuclear cells under permissive conditions. A five-fold increased HERV-K102 pol genomic copy number was found in the HESN cohort over normal which was not found in HIV-1 positive patients (p=0.0005).

Conclusions:

This work extends the evidence that HERV-K102 has foamy virus attributes, is replication competent, and is capable of high replication rate in vivo and in vitro. This may be the first characterization of a replication-competent, foamy-like virus of humans. High particle production inferred by increased integration in the HESN cohort over HIV-1 patients raises the issue of the clinical importance of HERV-K102 particle production as an early protective innate immune response against HIV-1 replication.

Efficacy of fewer than three doses of an HPV-16/18 AS04-adjuvanted vaccine: combined analysis of data from the Costa Rica Vaccine and PATRICIA Trials

BACKGROUND

There is some evidence to suggest that one or two doses of the HPV vaccine provides similar protection to the three-dose regimen. The main aim of the study was to ascertain HPV-16/18 vaccine efficacy in both full and naive cohorts and to explore protection conferred against non-vaccine HPV types, by number of doses received.

METHODS

Summary data from the Costa Rica Vaccine Trial (CVT; NCT00128661) and ~the PATRICIA trial (NCT001226810), two phase 3, double-blind, randomised controlled clinical trials of the HPV-16/18 AS04-adjuvanted vaccine in young women, were combined in a post-hoc analysis (GlaxoSmithKline [GSK] e-track number 202142) to investigate the efficacy of fewer than three doses of the HPV-16/18 vaccine after 4 years of follow-up. Women were randomly assigned to receive three doses of the HPV-16/18 vaccine or to a control vaccine; yet, some received fewer doses. After exclusion of women with less than 12 months of follow-up or those who were HPV-16/18 DNA-positive at enrolment (for the HPV-16/18 endpoint), we calculated vaccine efficacy against one-time detection of incident HPV infections after three, two, and one dose(s). The primary study endpoint was one-time detection of first incident HPV-16/18 infections accumulated during the follow-up phase.

FINDINGS

We assessed vaccine efficacy against incident HPV-16/18 infection in the modified total vaccinated cohort (22 327 received three doses, 1185 two doses, 543 one dose). Vaccine efficacy against incident HPV-16/18 infections for three doses was 77·0% (95% CI 74·7-79·1), two doses was 76·0% (62·0-85·3), and one dose was 85·7% (70·7-93·7). Vaccine efficacy against incident HPV-31/33/45 infections for three doses was 59·7% (56·0-63·0), two doses was 37·7% (12·4-55·9), and one dose was 36·6% (-5·4 to 62·2). Vaccine efficacy against incident HPV-16/18 infection for two-dose women who received their second dose at 1 month was 75·3% (54·2-87·5) and 82·6% (42·3-96·1) for those who received the second dose at 6 months (CVT data only). Vaccine efficacy against HPV-31/33/45 for two-dose women who received their second dose at 6 months (68·1%, 27·0-87·0; CVT data only), but not those receiving it at one month (10·1%, -42·0 to 43·3), was similar to the three-dose group.

INTERPRETATION

4 years after vaccination of women aged 15-25 years, one and two doses of the HPV-16/18 vaccine seem to protect against cervical HPV-16/18 infections, similar to the protection provided by the three-dose schedule. Two doses separated by 6 months additionally provided some cross-protection. These data argue for a direct assessment of one-dose efficacy of the HPV-16/18 vaccine.

FUNDING

US National Cancer Institute, National Institutes of Health Office of Research on Women's Health, and Ministry of Health of Costa Rica (CVT); GlaxoSmithKline Biologicals SA (PATRICIA).

Impact of polymerase chain reaction testing on Clostridium difficile infection rates in an acute health care facility

Two rapid methods of Clostridium difficile infection (CDI) diagnosis were compared between June 2012 and March 2013: a GeneXpert (Cepheid, Sunnyvale, Calif) polymerase chain reaction (PCR) test and an enzyme immunoassay (EIA). The influence of these methods on the detection of hospital-acquired CDI and identification of CDI outbreaks was evaluated. We tested 1,592 stool samples for C difficile. The GeneXpert PCR test identified 211 positive samples (68 determined to be hospital-acquired infection), whereas EIA identified 105 positive samples (36 determined to be hospital-acquired infection). The GeneXpert PCR method in contrast to the EIA method increased the detection rates of nosocomial CDI cases and contributed to the declaration of CDI outbreaks.

Potency of Cell-Mediated Immune Responses to Different Combined HIV-1 Immunogens in a Humanized Murine Model

In this study, cell-mediated immune responses were evaluated in HLA-A2.1 mice that received polycistronic vector expressing HIV-1 gp120, gag and pol or single vectors expressing gp120 + gag/pol as well as recombinant structural proteins and adjuvants. Mice primed with the polycistronic DNA/CpG and boosted with the same regimen plus proteins induced a higher T-cell proliferative response to gp120. However, a very high frequency of IFN-gamma was detected in mice receiving the mixture of gp120 + gag/pol DNA constructs, recombinant proteins and CpG. We also measured specific CD8+T cells in PBMCs by intracellular cytokine and HLA-A2.1-peptide dimer staining in response to HLA-A2.1-restricted HIV-1 epitopes (gp120, gag and pol). The group that received single gp120 + gag/pol DNA constructs, recombinant proteins and CpG had a higher CD8+T cell response to the combination of peptides compared to the other groups that received the polycistronic construct. The present study reveals an optimal combination of immunogens to enhance immune responses against HIV-1.

Interim estimates of 2013/14 influenza clinical severity and vaccine effectiveness in the prevention of laboratory-confirmed influenza-related hospitalisation, Canada, February 2014

Binary file ES_Abstracts_Final_ECDC.txt matches

The potential of 1018 ISS adjuvant in hepatitis B vaccines: HEPLISAV™ review

Hepatitis B (HBV) virus infects the liver, and upon chronic infection, can cause liver cirrhosis and hepatocellular carcinoma. Despite universal vaccination programs against the virus, HBV still affects over 2 billion people worldwide, with over 240 million developing a chronic infection. While current alum-adjuvanted vaccines have shown efficacy in promoting seroprotection in healthy adults, 5-10% of immune-competent populations fail to achieve long-lasting seroprotection from these formulations. Furthermore, a large proportion of immunocompromised patients fail to achieve seroprotective antibody titers after receiving these vaccines. A novel vaccine candidate, HEPLISAV™, uses immunostimulatory sequences (ISS), in its formulation that helps induce a robust humoral and cell mediated immunity against HBV. In Phase III clinical trials, HEPLISAV™ has been shown to elicit seroprotective antibody titers with fewer immunizations. Similar safety profiles are demonstrated when compared with current HBV vaccines. For these reasons, HEPLISAV™ is an attractive vaccine to combat this global disease.

Characterization of a branched lipopeptide candidate vaccine against influenza A/Puerto Rico 8/34 which is recognized by human B and T-cell immune responses

The use of synthetic peptides as immunogens represents an exciting alternative to traditional vaccines. However, to date most of these synthetic peptides are not highly immunogenic. The lack of immunogenicity might be addressed by conjugation between T or B cell epitopes with universal or immunodominant T-helper epitopes. The construction of lipidated peptides, branched peptides, or designs combining both of these elements might enhance the immunogenicity, as they might target Toll-Like Receptors and/or mimic the 3-dimensional structure of epitopes within the native protein. Herein, a recognized peptide immunogen based on the hemagglutinin protein of A/Puerto Rico/8/34 was chosen as a backbone and modified to evaluate if the construction of branched peptides, lipidation, the addition of cysteine residues, or mutations could indeed alter epitope reactivity. Screening the different designs with various antibody binding and cellular assays revealed that combining a branched design with the addition of lipid moieties greatly enhanced the immunoreactivity.

Synthetic antigens representing the antigenic variation of human hepatitis C virus

Immune responses against hepatitis C virus (HCV) have been studied by numerous groups. However, details concerning the production of antibodies to antigenically variable epitopes remain to be elucidated. Since the sequences of the variable regions of several HCV proteins are different among the virus strains infecting patients, we decided to design peptide combinations that represent the theoretical maximum antigenic variation of each epitope to be used as capture antigens. We prepared six peptide mixtures (hypervariable epitope constructs; HECs) representing six different epitopes from structural and non-structural proteins of HCV from genotypes 1-6. Plasma from 300 HCV patients was tested to determine if their antibodies recognize the synthetic constructs. All the patients were chronically infected with diverse HCV genotypes and did not receive antiviral treatment. Antibodies to one or more of the HECs were detected in all of the HCV-infected individuals. Immunogenicity of the HCV HECs was also evaluated in outbred and inbred mice. Strong HEC-specific antibodies were produced, and cellular responses were also induced that were Th-1 rather than Th-2. Our results show that HCV HECs are both antigens that can be used to detect the broad cross-reactivity of antibodies from HCV-infected patients, and strong immunogens that can induce antigen-specific humoral and cellular immune responses in mice.

Enhancing oral vaccine potency by targeting intestinal M cells

The immune system in the gastrointestinal tract plays a crucial role in the control of infection, as it constitutes the first line of defense against mucosal pathogens. The attractive features of oral immunization have led to the exploration of a variety of oral delivery systems. However, none of these oral delivery systems have been applied to existing commercial vaccines. To overcome this, a new generation of oral vaccine delivery systems that target antigens to gut-associated lymphoid tissue is required. One promising approach is to exploit the potential of microfold (M) cells by mimicking the entry of pathogens into these cells. Targeting specific receptors on the apical surface of M cells might enhance the entry of antigens, initiating the immune response and consequently leading to protection against mucosal pathogens. In this article, we briefly review the challenges associated with current oral vaccine delivery systems and discuss strategies that might potentially target mouse and human intestinal M cells.

Adoptive transfer of splenocytes to study cell-mediated immune responses in hepatitis C infection using HCV transgenic mice

Background

Hepatitis C virus (HCV) is a major cause of chronic hepatitis and a health problem affecting over 170 million people around the world. We previously studied transgenic mice that express HCV Core, Envelope 1 and Envelope 2 proteins predominantly in the liver, resulting in steatosis, liver and lymphoid tumors, and hepatocellular carcinoma. Herein, the immune-mediated cell response to hepatitis C antigens was evaluated by adoptive transfers of carboxyfluorescein succinimidyl ester (CFSE) labelled splenocytes from HCV immunized mice into HCV transgenic mice.

Results

In comparison to non-transgenic mice, there was a significant decrease in the percentage of CFSE-labeled CD4⁺ and CD8⁺ T cells in transgenic mouse peripheral blood receiving adoptive transfers from immunized donors. Moreover, the percentage of CFSE-labeled CD4⁺ and CD8⁺ T cells were significantly higher in the spleen of transgenic and non-transgenic mice when they received splenocytes from non-immunized than from immunized mice. On the other hand, the percentages of CD4⁺ and CD8⁺ T cells in the non-transgenic recipient mouse lymph nodes were significantly higher than the transgenic mice when they received the adoptive transfer from immunized donors. Interestingly, livers of transgenic mice that received transfers from immunized mice had a significantly higher percentage of CFSE labeled T cells than livers of non-transgenic mice receiving non-immunized transfers.

Conclusions

These results suggest that the T cells from HCV immunized mice recognize the HCV proteins in the liver of the transgenic mouse model and homed to the HCV antigen expression sites. We propose using this model system to study active T cell responses in HCV infection.

Safety and immunogenicity of an investigational quadrivalent meningococcal conjugate vaccine after one or two doses given to infants and toddlers

With the emergence of multiple meningococcal serogroups in different geographic areas, broad vaccine protection from infancy is desirable. One hundred and seventy-five infants received either two doses of a meningococcal quadrivalent (A, C, W-135, Y) conjugate vaccine (MenACWY-CRM) at 6 and 12 months, one dose of MenACWY-CRM at 12 months, or MenC at 12 months and MenACWY-CRM at 18 months. Bactericidal antibody titers using human complement were measured before and 1 month after each dose. Injection-site reactions were reported by 22-45% of participants following MenACWY-CRM given at 6 or 12 months. Similar proportions of subjects had injection-site reactions following two doses of MenACWY-CRM (32-41%) or one dose of MenC (26-44%). The incidence of systemic adverse events was comparable between groups. After two doses of MenACWY-CRM, the percentages of participants reporting hSBA titers >or=8 were 100% for C, W-135, and Y, and 84% for A. Serogroup C titers were more than 10-fold higher after two doses of MenACWY-CRM than after one dose of MenC or MenACWY-CRM at 12 months. Serogroup C titers were comparable following a single dose of MenACWY-CRM or MenC at 12 months. MenACWY-CRM is well tolerated and immunogenic given at 12 months, or two doses at 6 and 12 months of age.

Detection of influenza A and B neutralizing antibodies in vaccinated ferrets and macaques using specific biotin-streptavidin conjugated antibodies

Several critical factors of an influenza microneutralization assay, utilizing a rapid biotin-streptavidin conjugated system for detecting influenza virus subtypes A and B, are addressed within this manuscript. Factors such as incubation times, amount of virus, cell seeding, sonication, and TPCK trypsin were evaluated for their ability to affect influenza virus neutralization in a microplate-based neutralization assay using Madin-Darby canine kidney (MDCK) cells. It is apparent that the amount of virus used in the assay is the most critical factor to be optimized in an influenza microneutralization assay. Results indicate that 100xTCID(50) of influenza A/Solomon Islands/03/2006 (H1N1) virus overloads the assay and results in no, to low, neutralization, in both ferret and macaque sera, respectively, whereas using 6xTCID(50) resulted in significantly improved neutralization. Conversely, strong neutralization was observed against 100xTCID(50) of B/Malaysia/2506/04 virus. In this manuscript the critical factors described above were optimized and the results indicate that the described biotin-streptavidin conjugated influenza microneutralization assay is a rapid and robust method for detecting the presence of functional, influenza virus-neutralizing antibodies.

Long-term antibody persistence induced by a combined hepatitis A and B vaccine in children and adolescents

Two cohorts, comprising of subjects aged 1-6 years and 6-15 years were vaccinated with Twinrix according to a 0-, 1- and 6-month schedule. The 1-6 years cohort was followed up for 7.5 years and the 6-15 years cohort for 10 years. At the latest follow-up time point, all subjects were seropositive for anti-HAV antibodies, while 86.5% (32/37) and 95.5% (21/22) had anti-HBs >or= 10 mIU/ml in the 1-6 years and in the 6-15 years cohort. The geometric mean concentrations (GMCs; mIU/ml) were 233 and 680 for anti-HAV antibodies, and 147 and 165 for anti-HBs antibodies, in the 1-6 years and 6-15 years cohorts, respectively. The high persistence of circulating anti-HAV and anti-HBs antibodies in children and adolescents demonstrates the long-term protection offered by Twinrix in these age groups.