Simplified dosing of oral azithromycin for children 1-11 months old in child survival programmes: age-based and height-based dosing protocols.

BACKGROUND: To facilitate mass distribution of azithromycin, trachoma control programmes use height instead of weight to determine dose for children 6 months to 15 years old. WHO has recommended azithromycin distribution to children 1-11 months old to reduce mortality in high mortality settings under carefully monitored conditions. Weight was used to determine dose in children 1-5 months old in studies of azithromycin distribution for child survival, but a simplified approach using age or height for all aged 1-11 months old could increase programme efficiency in real-world settings. METHODS: This secondary analysis used data from two cluster randomised trials of azithromycin distribution for child mortality in Niger and Burkina Faso. An exhaustive search algorithm was developed to determine the optimal dose for different age groups, using tolerance limits of 10-20 mg/kg for children 1-2 months old and 15-30 mg/kg for children 3-11 months old. Height-based dosing was evaluated against the existing trachoma dosing pole and with a similar exhaustive search. RESULTS: The optimal two-tiered age-based approach suggested a dose of 80 mg (2 mL) for children 1-2 months old and 160 mg (4 mL) for children 3-11 months old. Under this schedule, 89%-93% of children would have received doses within tolerance limits in both study populations. Accuracy was 93%-94% with a three-tiered approach, which resulted in doses of 80 mg (2 mL), 120 mg (3 mL) and 160 mg (4 mL) for children 1-2, 3-4 and 5-11 months old, respectively. For children 1-5 months old, the existing height pole would result in 70% of doses within tolerance limits. The optimisation identified height-based dosing options with 95% accuracy, although this would require changes to the existing dosing pole as well as additional training to measure infants lying flat. CONCLUSIONS: Overall, an age-based approach with two age tiers resulted in high accuracy while considering both concerns about overdosing in this young population and simplicity of field operations.

Safety and immunogenicity of different Clostridioides (Clostridium) difficile vaccine formulations in two early phase randomized studies of healthy adults aged 50-85 years.

BACKGROUND: Two phase 1/phase 2 studies assessed 2 formulations of investigational bivalent Clostridioides (Clostridium) difficile vaccine (QS-21 adjuvanted toxoid and toxoid-alone) in healthy adults 50-85 years of age. METHODS: The QS-21 adjuvanted toxoid vaccine study randomized subjects 3:1 to 100 µg QS-21-containing C difficile vaccine or placebo administered in a shortened-month (Months 0, 1, 3) or day (Days 1, 8, 30) regimen. The toxoid-alone vaccine study randomized subjects 3:3:1 to receive 100 or 200 µg unadjuvanted C difficile vaccine formulation or placebo in Stages 1 and 2 (sentinel cohorts of different age groups), and 3:1 to receive the selected dose of unadjuvanted C difficile vaccine formulation or placebo in Stage 3 (Days 1, 8, 30). Safety was the primary outcome for both studies. Immunogenicity was determined by measuring serum toxin A- and B-specific neutralizing antibodies. RESULTS: In the day regimen, 10 reports across both studies of grade 3 injection site redness postdose 2 triggered predefined stopping rules. Local reactions in both studies were more common among vaccine versus placebo recipients. Injection site pain predominated and was generally mild in severity. Systemic events were infrequent and generally mild-to-moderate in severity. Adverse events were reported by 50.0%-75.0% and 16.7%-50.0% of subjects in the QS-21 and toxoid-alone studies, respectively. Immune responses peaked around Day 37 (shortened-month regimen) or between Day 15 and Month 2 (day regimen) and remained above baseline throughout follow-up. CONCLUSIONS: Both formulations demonstrated robust immunogenicity. Both studies stopped early due to grade 3 injection site redness postdose 2 of the day regimen; neither formulation progressed to later stage development. Instead, an aluminum hydroxide-containing formulation of the vaccine candidate administered at 0, 1, and 6 months, which was safe and immunogenic in phase 1 and 2 studies, advanced to phase 3 studies.

The Weight of Evidence From Electrophysiology, Observational, and Cardiovascular End Point Studies Demonstrates the Safety of Azithromycin.

Increased use of azithromycin (AZ) in treating infections associated with coronavirus disease 2019 (COVID-19) and reports of increased incidence of prolonged corrected QT (QTc) interval associated with AZ used with hydroxychloroquine prompted us to review the latest evidence in the literature, present additional analyses of human cardiovascular (CV) electrophysiology studies, and to describe sequential steps in research and development that were undertaken to characterize the benefit-risk profile of AZ. Combined QTc findings from electrocardiograms taken during oral and i.v. pharmacokinetic-pharmacodynamic studies of AZ suggest that clinically meaningful QTc prolongation is unlikely. Findings from several observational studies were heterogeneous and not as consistent as results from at least two large randomized controlled trials (RCTs). The QTc findings presented and observational data from studies with large numbers of events are not consistent with either a proarrhythmic action of AZ or an increase in frequency of CV deaths. Well-powered RCTs do not suggest a presence of increased risk of CV or sudden cardiac death after short-term or protracted periods of AZ usage, even in patients at higher risk from pre-existing coronary disease.

A Phase 2 Study Evaluating the Safety, Tolerability, and Immunogenicity of Two 3-Dose Regimens of a Clostridium difficile Vaccine in Healthy US Adults Aged 65 to 85 Years.

BACKGROUND: Clostridium difficile causes toxin-mediated nosocomial diarrhea and community-acquired infections; no preventive vaccine is licensed. In this phase 2 study, we explored safety, tolerability, and immunogenicity in older US adults of an investigational bivalent C. difficile vaccine that contains equal dosages of genetically and chemically detoxified toxins A and B. METHODS: Conducted from July 2015 through March 2017, 855 healthy adults aged 65-85 years from 15 US centers were randomized 3:3:1 to receive vaccine (100 or 200 µg) or placebo at 0, 1, and 6 months (month regimen) or 1, 8, and 30 days (day regimen). Serum toxin A- and B-specific neutralizing antibodies were measured. Participant-reported local reactions (LRs) and systemic events (SEs), adverse events (AEs), serious AEs, newly diagnosed chronic medical conditions, and immediate AEs were recorded. RESULTS: The 200-µg dose level elicited higher immune responses than the 100-µg dose level across regimens. Compared with the day regimen, the month regimen induced stronger and more persistent immune responses that remained elevated 12 months after dose 3. Responses peaked at month 7 (month regimen) and day 37 (day regimen). LRs (primarily injection site pain) were more frequent in vaccine recipients than controls; SE frequency was similar across groups. More related AEs were reported in the day regimen group than the month regimen group. CONCLUSIONS: The C. difficile vaccine was safe, well tolerated, and immunogenic in healthy US adults aged 65-85 years. Immune responses were particularly robust in the 200-µg month regimen group. These results support continued vaccine development. CLINICAL TRIALS REGISTRATION: NCT02561195.

A phase 1 randomized study assessing safety and immunogenicity of two 3-dose regimens of a Clostridium difficile vaccine in healthy older Japanese adults.

BACKGROUND: Clostridium difficile infection (CDI) is a major global cause of nosocomial and community-acquired infections. Despite potentially severe or fatal complications and frequent recurrence, no preventive vaccine is currently available. This randomized, observer-blinded, placebo-controlled phase 1 study in older Japanese adults evaluated safety and immunogenicity of an investigational C difficile vaccine containing a mixture of genetically detoxified and chemically inactivated toxoids, A and B. METHODS: Healthy Japanese adults aged 65 to 85 years were randomized in a 3:3:2 ratio to receive 100 or 200 µg of C difficile vaccine or placebo, respectively, at 0, 1, and 6 months (month regimen) or 1, 8, and 30 days (day regimen). The primary objective was safety evaluation. Vaccine immunogenicity, the secondary objective, was determined by assessing toxin A- and toxin B-specific neutralizing antibody levels in human sera. RESULTS: Local reactions were reported by up to 33.3% of subjects per dose in the month regimen; percentages were generally higher in the 200-µg group. Such reactions were all mild or moderate in severity and generally transient. No adverse events in the month regimen led to subject withdrawal, and no serious adverse events were considered vaccine related. Further enrollment and dosing in the day regimen were discontinued after 3 subjects in the 100-µg group reported severe redness after dose 2. In the month regimen study arm, immune responses as measured by toxin-neutralizing antibody geometric mean concentrations, geometric mean fold rises, and proportions of subjects achieving prespecified fold rises were generally higher in the 200-µg group, peaked at month 7, and remained elevated at month 12. CONCLUSIONS: The C difficile vaccine candidate was safe, well tolerated, and immunogenic when administered to healthy older Japanese adults at 0, 1, and 6 months. Results support continued development of the vaccine for the prevention of CDI. ClinicalTrials.gov identifier: NCT02725437.

The role of vaccines in preventing bacterial antimicrobial resistance.

Antimicrobial resistance (AMR) and the associated morbidity and mortality due to bacterial pathogens have been increasing globally to alarming levels. The World Health Organization (WHO) has called for global action on AMR, supported worldwide by governments, health ministries and health agencies. Many potential solutions to stem AMR are being discussed and implemented. These include increases in antimicrobial stewardship, investment in research and development to design new classes of antibiotics, and reduction of antibiotic use in rearing of livestock. However, vaccines as tools to reduce AMR have historically been under-recognized in these discussions, even though their effectiveness in reducing disease and AMR is well documented. This review article seeks to highlight the value of vaccines as an additional modality to combat AMR globally, using select examples. It also will provide perspectives on how vaccines could be more effectively used in this effort.

Streamlining Safety Data Collection in Hospital-Acquired Bacterial Pneumonia and Ventilator-Associated Bacterial Pneumonia Trials: Recommendations of the Clinical Trials Transformation Initiative Antibacterial Drug Development Project Team.

BACKGROUND: Resistant bacteria are one of the leading causes of hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP). HABP/VABP trials are complex and difficult to conduct due to the large number of medical procedures, adverse events, and concomitant medications involved. Differences in the legislative frameworks between different regions of the world may also lead to excessive data collection. The Clinical Trials Transformation Initiative (CTTI) seeks to advance antibacterial drug development (ABDD) by streamlining clinical trials to improve efficiency and feasibility while maintaining ethical rigor, patient safety, information value, and scientific validity. METHODS: In 2013, CTTI engaged a multidisciplinary group of experts to discuss challenges impeding the conduct of HABP/VABP trials. Separate workstreams identified challenges associated with current data collection processes. Experts defined "data collection" as the act of capturing and reporting certain data on the case report form as opposed to recording of data as part of routine clinical care. The ABDD Project Team developed strategies for streamlining safety data collection in HABP/VABP trials using a Quality by Design approach. RESULTS: Current safety data collection processes in HABP/VABP trials often include extraneous information. More targeted strategies for safety data collection in HABP/VABP trials will rely on optimal protocol design and prespecification of which safety data are essential to satisfy regulatory reporting requirements. CONCLUSIONS: A consensus and a cultural change in clinical trial design and conduct, which involve recognition of the need for more efficient data collection, are urgently needed to advance ABDD and to improve HABP/VABP trials in particular.

Improving Conduct and Feasibility of Clinical Trials to Evaluate Antibacterial Drugs to Treat Hospital-Acquired Bacterial Pneumonia and Ventilator-Associated Bacterial Pneumonia: Recommendations of the Clinical Trials Transformation Initiative Antibacterial Drug Development Project Team.

BACKGROUND: The etiology of hospital-acquired or ventilator-associated bacterial pneumonia (HABP/VABP) is often multidrug-resistant infections. The evaluation of new antibacterial drugs for efficacy in this population is important, as many antibacterial drugs have demonstrated limitations when studied in this population. HABP/VABP trials are expensive and challenging to conduct due to protocol complexity and low patient enrollment, among other factors. The Clinical Trials Transformation Initiative (CTTI) seeks to advance antibacterial drug development by streamlining HABP/VABP clinical trials to improve efficiency and feasibility while maintaining ethical rigor, patient safety, information value, and scientific validity. METHODS: In 2013, CTTI engaged a multidisciplinary group of experts to discuss challenges impeding the conduct of HABP/VABP trials. Separate workstreams identified challenges associated with HABP/VABP protocol complexity. The Project Team developed potential solutions to streamline HABP/VABP trials using a Quality by Design approach. RESULTS: CTTI recommendations focus on 4 key areas to improve HABP/VABP trials: informed consent processes/practices, protocol design, choice of an institutional review board (IRB), and trial outcomes. Informed consent processes should include legally authorized representatives. Protocol design decisions should focus on eligibility criteria, prestudy antibacterial therapy considerations, use of new diagnostics, and sample size. CTTI recommends that sponsors use a central IRB and discuss trial endpoints with regulators, including defining a clinical failure and evaluating the impact of concomitant antibacterial drugs. CONCLUSIONS: Streamlining HABP/VABP trials by addressing key protocol elements can improve trial startup and patient recruitment/retention, reduce trial complexity and costs, and ensure patient safety while advancing antibacterial drug development.

Responsibilities of Data Monitoring Committees: Consensus Recommendations.

BACKGROUND: A data monitoring committee (DMC) has special responsibilities for protecting the safety of clinical trial participants. Few guidance documents are available that address the operations and mechanics of establishing, serving on, or reporting to a DMC. This article provides a practical guide to sponsors, institutions, and individuals responsible for, or serving on, a DMC. METHODS: A workgroup of professionals from academia and not-for-profit and commercial organizations that included investigators, statisticians, patient advocates, and ethicists met to define the essential elements of planning, coordinating, and populating a DMC. All members of the group have formed, served on, advised, or worked with DMCs. RESULTS: The group outlined the objectives and mechanics of running a DMC, including operational and practical considerations, membership characteristics, roles, members' liability, and indemnification. Further, it delineated the roles and responsibilities of each DMC member. CONCLUSIONS: The group recommended practices for each phase of the DMC process from inception through execution of a clinical trial, with appropriate considerations for confidentiality. The group's practical guidance should assist in comprehensive oversight of appropriate clinical trials and should help DMC members execute their obligations with greater assurance.

Development of maraviroc, a CCR5 antagonist for treatment of HIV, using a novel tropism assay.

Assays to identify infectious organisms are critical for diagnosis and enabling the development of therapeutic agents. The demonstration that individuals with a 32-bp deletion within the CCR5 locus were resistant to human immunodeficiency virus (HIV) infection, while those heterozygous for the mutation progressed more slowly, led to the discovery of maraviroc (MVC), a CCR5 antagonist. As MVC is only active against CCR5-tropic strains of HIV, it was critical to develop a diagnostic assay to identify appropriate patients. Trofile™, a novel phenotypic tropism assay, was used to identify patients with CCR5-tropic virus for the MVC development program. Results of these clinical studies demonstrated that the assay correctly identified patients likely to respond to MVC. Over time, the performance characteristics of the phenotypic assay were enhanced, necessitating retesting of study samples. Genotypic tropism tests that have the potential to allow for local use and more rapid turnaround times are also being developed.

Vaccines: A review of immune-based interventions to prevent and treat disease.

The enormous gains made in public health during the 20th century, through the prevention and treatment of infectious disease, have contributed to dramatic improvements in the quality and length of the human lifespan. Continued advances in medicine are dependent on addressing several challenges including the increase in existing and new resistance to antibiotics, the decrease in productivity of the research and development (R&D) ecosystem, uncertain regulatory pathways, and an economic environment that rewards innovation for developing therapeutics that involve long cycle times from idea to a product. In this article, we consider important issues pertaining to the development of vaccines with particular emphasis on preclinical requirements, optimal dose selection, design, execution, and reporting of clinical trials for regulatory submission, planning and implementation of post-approval life-cycle programs, and emerging themes in therapeutic vaccines.

A comprehensive regulatory framework to address the unmet need for new antibacterial treatments.

To bring new antibacterial drugs to the market is challenging because discovery of new agents is difficult, two large trials per indication are needed in accordance with traditional regulatory requirements, and the economic reward is limited if the use of new antibiotics is constrained. These challenges have resulted in an alarmingly thin antibiotic pipeline, despite the rapid and continued growth in the need for new drugs. Approaches that balance the quantity of data needed for registration with the unmet medical need would encourage work in this area. Therefore, a tiered regulatory framework that allows either disease-based or pathogen-based label indications is proposed, with label wording that promotes the most appropriate use of new agents. Such a framework is within the bounds of present regulatory approaches, is amenable to international harmonisation, and would be a welcome step towards the facilitation of a robust and sustainable discovery and development infrastructure.

A paradigm shift in drug development for treatment of rare multidrug-resistant gram-negative pathogens.

Multidrug-resistant (MDR) gram-negative pathogens pose a major threat to patients worldwide. Although the organisms remain relatively uncommon overall, their incidence is steadily increasing with associated increases in mortality and pharmacoeconomic impact. As evidenced by the dearth of new products in the pipeline or in clinical use, the conventional paradigm for the development of drugs against such pathogens is generally ineffectual. We advocate the need for a shift in the current paradigm and propose innovative development programs that involve implementation of a graduated approval process. The initial phase of the proposed regulatory paradigm includes early approval of a new drug based on a robust nonrandomized study, buttressed by data from concurrent controls and a pharmacokinetic-pharmacodynamic package generated from nonclinical studies. The postapproval commitment phase will include a randomized controlled trial, when disease prevalence permits, as well as continued assessment of risks and benefits under "real world" settings.

Bias associated with mining electronic health records.

Large-scale electronic health record research introduces biases compared to traditional manually curated retrospective research. We used data from a community-acquired pneumonia study for which we had a gold standard to illustrate such biases. The challenges include data inaccuracy, incompleteness, and complexity, and they can produce in distorted results. We found that a naïve approach approximated the gold standard, but errors on a minority of cases shifted mortality substantially. Manual review revealed errors in both selecting and characterizing the cohort, and narrowing the cohort improved the result. Nevertheless, a significantly narrowed cohort might contain its own biases that would be difficult to estimate.

Complicated skin and skin-structure infections and catheter-related bloodstream infections: noninferiority of linezolid in a phase 3 study.

BACKGROUND: Catheter-related bloodstream infection (CRBSI) causes substantial morbidity and mortality, but few randomized, controlled studies have been conducted to guide therapeutic interventions. METHODS: To determine whether linezolid would be noninferior to vancomycin in patients with CRBSI, we conducted an open-label, multicenter, comparative study. Patients with suspected CRBSI were randomized to receive linezolid or vancomycin (control group). The primary end point was microbiologic outcome at test of cure 1-2 weeks after treatment, as assessed by step-down procedure. The first analysis population was complicated skin and skin structure infection (cSSSI) in patients with suspected CRBSI; patients with CRBSI were analyzed if noninferiority criteria (lower bound of the 95% confidence interval [CI] not outside -15%) were met. RESULTS: Noninferiority criteria were met for cSSSI (microbiologic success rate for linezolid recipients, 89.6% [146 for 163 patients]; for the control group, 89.9% [134 of 149]; 95% CI, -7.1 to 6.4) and CRBSI (for linezolid recipients, 86.3% [82 of 95]; for the control group, 90.5% [67 of 74]; 95% CI, -13.8 to 5.4). The frequency and severity of adverse events were similar between groups. Mortality rates were 10.4% for linezolid recipients (28 of 269 patients) and 10.1% for control subjects (26 of 257) in the modified intent-to-treat population (i.e., all patients with gram-positive baseline culture) through test of cure, and they were 21.5% for linezolid recipients (78 of 363) and 16.0% for the control group (58 of 363; 95% CI, -0.2 to 11.2) for all treated patients through poststudy treatment day 84. CONCLUSIONS: Linezolid demonstrated microbiologic success rates noninferior to those for vancomycin in patients with cSSSIs and CRBSIs caused by gram-positive organisms. Patients with catheter-related infections must be carefully investigated for the heterogeneous underlying causes of high morbidity and mortality, particularly for infections with gram-negative organisms.

The effect of azithromycin on ivermectin pharmacokinetics--a population pharmacokinetic model analysis.

BACKGROUND: A recent drug interaction study reported that when azithromycin was administered with the combination of ivermectin and albendazole, there were modest increases in ivermectin pharmacokinetic parameters. Data from this study were reanalyzed to further explore this observation. A compartmental model was developed and 1,000 interaction studies were simulated to explore extreme high ivermectin values that might occur. METHODS AND FINDINGS: A two-compartment pharmacokinetic model with first-order elimination and absorption was developed. The chosen final model had 7 fixed-effect parameters and 8 random-effect parameters. Because some of the modeling parameters and their variances were not distributed normally, a second mixture model was developed to further explore these data. The mixture model had two additional fixed parameters and identified two populations, A (55% of subjects), where there was no change in bioavailability, and B (45% of subjects), where ivermectin bioavailability was increased 37%. Simulations of the data using both models were similar, and showed that the highest ivermectin concentrations fell in the range of 115-201 ng/mL. CONCLUSIONS: This is the first pharmacokinetic model of ivermectin. It demonstrates the utility of two modeling approaches to explore drug interactions, especially where there may be population heterogeneity. The mechanism for the interaction was identified (an increase in bioavailability in one subpopulation). Simulations show that the maximum ivermectin exposures that might be observed during co-administration with azithromycin are below those previously shown to be safe and well tolerated. These analyses support further study of co-administration of azithromycin with the widely used agents ivermectin and albendazole, under field conditions in disease control programs.

Pharmacokinetics of azithromycin and the combination of ivermectin and albendazole when administered alone and concurrently in healthy volunteers.

Azithromycin is a critical component of an integrated disease elimination program against trachoma. This study was conducted to evaluate whether azithromycin has a pharmacokinetic interaction with the combination of ivermectin and albendazole. Eighteen healthy volunteers were administered single doses of azithromycin, ivermectin/albendazole, and the combination of the three agents in random, crossover fashion. To assess the presence of interactions, test (combination) and reference (single dose) data were compared using an estimation approach. Compared with reference phases, the geometric mean values for the combination arm's azithromycin AUC(0-t) and C(max) were increased approximately 13% and 20%, respectively, albendazole AUC(0-t) decreased by approximately 3% and C(max) increased approximately 3%, and ivermectin AUC(0-t) and C(max) were increased 31% and 27%, respectively. Albendazole sulfoxide AUC(0-t) and C(max) were decreased approximately 16% and 14%, respectively. All treatments were well tolerated. The interactions for azithromycin and albendazole were minimal although the increase in ivermectin exposure requires further study.