Design of clinical trials of antibacterial agents for community-acquired bacterial pneumonia

Developing Consensus on Clinical Outcomes for Children with Mild Pneumonia: A Delphi Study

BACKGROUND

The absence of consensus for outcomes in pediatric antibiotic trials is a major barrier to research harmonization and clinical translation. We sought to develop expert consensus on study outcomes for clinical trials of children with mild community-acquired pneumonia (CAP).

METHODS

Applying the Delphi method, a multispecialty expert panel ranked the importance of various components of clinical response and treatment failure outcomes in children with mild CAP for use in research. During Round 1, panelists suggested additional outcomes in open-ended responses that were added to subsequent rounds of consensus building. For Rounds 2 and 3, panelists were provided their own prior responses and summary statistics for each item in the previous round. The consensus was defined by >70% agreement.

RESULTS

The expert panel determined that response to and failure of treatment should be addressed at a median of 3 days after initiation. Complete or substantial improvement in fever, work of breathing, dyspnea, tachypnea when afebrile, oral intake, and activity should be included as components of adequate clinical response outcomes. Clinical signs and symptoms including persistent or worsening fever, work of breathing, and reduced oral intake should be included in treatment failure outcomes. Interventions including receipt of parenteral fluids, supplemental oxygen, need for high-flow nasal cannula oxygen therapy, and change in prescription of antibiotics should also be considered in treatment failure outcomes.

CONCLUSIONS

Clinical response and treatment failure outcomes determined by the consensus of this multidisciplinary expert panel can be used for pediatric CAP studies to provide objective data translatable to clinical practice.

Observational versus randomized controlled trials to inform antibiotic treatment durations: a narrative review

BACKGROUND

Studies comparing shorter and longer antibiotic treatment durations are increasingly common. Randomized controlled trials (RCTs) are an ideal methodological approach to study antibiotic treatment durations; however, these trials can be logistically and financially challenging to conduct.

OBJECTIVES

In this narrative review, we sought to compare the strengths and limitations of observational study data with those of RCT data in evaluating antibiotic treatment durations. We used uncomplicated Gram-negative bacteraemia as an illustrative case example because several published RCTs and observational studies have been conducted in similar patient populations.

SOURCES

We searched MEDLINE for articles comparing treatment durations for gram-negative bacteremia from inception to June 9th, 2022. We included studies reporting on all-cause mortality and/or relapse at day 28-30. Data comparing short- versus long-course therapy were pooled by Bayesian random effects meta-analyses to assess the odds ratios (OR) of all-cause mortality and relapse at 30 days, stratified by study design. Parameters were summarized with median and 95% highest-density credible intervals (CrI). Posterior probabilities of OR > 1.0 were estimated. Observational studies were further examined to determine if and how they addressed potential sources of bias.

CONTENT

We identified 1671 unique records and included 10 studies (seven observational and three RCTs). With respect to 30-day mortality, the Bayesian posterior probability that a longer course of therapy was better (i.e. OR >1.0) was 42% in RCTs (OR, 0.94; 95% CrI, 0.51-1.68) and 91% in observational studies (OR, 1.25; 95% CrI, 0.88-1.73). No observational study fully addressed all potential sources of bias.

IMPLICATIONS

On the basis of our findings, we discuss future directions for antibiotic treatment duration trials, including approaches to limit sources of bias in observation data and novel trial designs.

Discordance Among Antibiotic Prescription Guidelines Reflects a Lack of Clear Best Practices

Background

Antibiotics are among the most frequently administered drugs globally, yet they are often prescribed inappropriately. Guidelines for prescribing are developed by expert committees at international and national levels to form regional standards and by local experts to form hospital guidance documents. Our aim was to assess variability in antibiotic prescription guidelines for both regional standards and individual hospitals.

Methods

A search through 3 publicly accessible databases from February to June 2018 led to a corpus of English language guidance documents from 70 hospitals in 12 countries and regional standards from 7 academic societies.

Results

Guidelines varied markedly in content and structure, reflecting a paucity of rules governing their format. We compared recommendations for 3 common bacterial infections: community-acquired pneumonia, urinary tract infection, and cellulitis. Hospital guidance documents and regional standards frequently disagreed on preferable antibiotic classes for common infections. Where agreement was observed, guidance documents appeared to inherit recommendations from their respective regional standards. Several regional prescribing patterns were identified, including a greater reliance on penicillins over cephalosporins in the United Kingdom and fluoroquinolones in the United States. Regional prescribing patterns could not be explained by antibiotic resistance or costs. Additionally, literature that cited underlying recommendations did not support the magnitude of recommendation differences observed.

Conclusions

The observed discordance among prescription recommendations highlights a lack of evidence for superior treatments, likely resulting from a preponderance of noninferiority trials comparing antibiotics. In response, we make several suggestions for developing guidelines that support best practices of antibiotic stewardship.

Concordance of early and late endpoints for community-acquired bacterial pneumonia trials

BACKGROUND

While there are ongoing regulatory convergence efforts, differences remain in primary endpoints recommended for community-acquired bacterial pneumonia (CABP) trials. The US Food and Drug Administration recommends assessing CABP symptom resolution at an early time point (3-5 days after randomization). Other regulatory agencies recommend assessing overall clinical response at a later time point (5-10 days after therapy ends).

METHODS

We analyzed participant-level data from six recent CABP trials submitted to the FDA (n=4,645 participants) to evaluate concordance between early and late endpoint outcomes. We used multivariate logistic regression to identify factors associated with discordance.

RESULTS

Early and late endpoint outcomes were concordant for 85.6% of participants. The proportions of early endpoint responders that ultimately failed and early endpoint non-responders that ultimately succeeded were similar (6.0% vs 8.4%, respectively). Early endpoint response was highly predictive of late endpoint success (positive predictive value 92.9%). Multivariate logistic regression identified early endpoint responders/late endpoint failures as less likely to be obese and more likely to be infected with Chlamydophila pneumoniae or Staphylococcus aureus, have received antibacterial drug therapy prior to randomization, and have severe chest pain at baseline. The most common investigator-provided reasons for failure among early endpoint responders/late endpoint failures were receipt of non-study antibacterial drug therapy and loss to follow-up.

CONCLUSION

Early and late endpoint outcomes were highly concordant. These data may be useful in the continuing efforts to reach international regulatory convergence on CABP clinical trial design recommendations.

A look at clinical trial design for new antimicrobials for the adult population

Introduction: Antimicrobial resistance poses a substantial threat to global public health since it decreases the probability of effectively treating an infection and increases the risk of morbidity and mortality.Areas covered: In this review, the authors discuss the advantages and disadvantages of classical and novel trial designs for evaluating novel antibiotics for infections due to multidrug-resistant organisms (MDRO). An inductive literature search was performed using different keywords pertinent to the reviewed topics.Expert opinion: The need for active, effective compounds has strengthened regulatory, academic, and industry cooperation, leading to the recent approval of some novel anti-MDRO agents, with other promising compounds being also in the late phase of clinical development. Nonetheless, some important issues regarding the design of clinical trials have gained importance that are peculiar for novel anti-MDRO agents and should be addressed for continuing to guarantee the availability of effective treatments in the future. Very importantly, concerted cooperation with regulatory agencies will always be needed for continuously discussing and refining the acceptable level of evidence to be pursued through non-conventional and/or innovative trial designs or development strategies. Failure to do so would seriously pose the risk of perpetuating the unmet need for effective anti-MDRO agents.

A Retrospective Analysis of Probability of Target Attainment in Community-Acquired Pneumonia: Ceftaroline Fosamil Versus Comparators

Introduction

This retrospective analysis compares the probability of target attainment (PTA) for ceftriaxone, levofloxacin and ceftaroline fosamil against Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae in a representative patient population with moderate-to-severe community-acquired pneumonia (CAP).

Methods

Published pharmacokinetic (PK) models for levofloxacin and ceftriaxone, and an existing model for ceftaroline, were used with standard dosage regimens for simulating individual PK data with covariates representative of patients with CAP (5000 patients/drug regimen). PTA for clinically relevant pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated from steady state PK profiles for a range of minimum inhibitory concentrations (MICs). Cumulative fractions of response (CFRs) were also calculated using MIC distributions from 2012 to 2017 global surveillance data.

Results

Ceftaroline fosamil (600 mg q12 h) achieved > 90% PTA at all exposure targets for each pathogen at European Committee on Antimicrobial Susceptibility Testing (EUCAST)/Clinical and Laboratory Standards Institute (CLSI) susceptibility breakpoints, and CFRs were > 99%. Ceftriaxone, but not levofloxacin, achieved 100% PTA and > 90% CFR against S. pneumoniae. Both levofloxacin and ceftriaxone achieved high PTA and CFR against H. influenzae. Levofloxacin achieved PTAs < 90% at EUCAST/CLSI breakpoints and ceftriaxone achieved PTAs < 90% at MICs up to 2 mg/L against S. aureus; both agents produced generally low CFRs against S. aureus (except levofloxacin against methicillin-sensitive S. aureus), reflecting the lack of activity of these agents against methicillin-resistant S. aureus.

Conclusion

Ceftaroline fosamil demonstrated higher overall PTA rates than levofloxacin and ceftriaxone, in particular against S. aureus. These results provide insight regarding the potential comparative efficacy of the described antibiotics for moderate-to-severe CAP.

Funding

Pfizer.

Novel approaches are needed to develop tomorrow's antibacterial therapies

Society faces a crisis of rising antibiotic resistance even as the pipeline of new antibiotics has been drying up. Antibiotics are a public trust; every individual's use of antibiotics affects their efficacy for everyone else. As such, responses to the antibiotic crisis must take a societal perspective. The market failure of antibiotics is due to a combination of scientific challenges to discovering and developing new antibiotics, unfavorable economics, and a hostile regulatory environment. Scientific solutions include changing the way we screen for new antibiotics. More transformationally, developing new treatments that seek to disarm pathogens without killing them, or that modulate the host inflammatory response to infection, will reduce selective pressure and hence minimize resistance emergence. Economic transformation will require new business models to support antibiotic development. Finally, regulatory reform is needed so that clinical development programs are feasible, rigorous, and clinically relevant. Pulmonary and critical care specialists can have tremendous impact on the continued availability of effective antibiotics. Encouraging use of molecular diagnostic tests to allow pathogen-targeted, narrow-spectrum antibiotic therapy, using short rather than unnecessarily long course therapy, reducing inappropriate antibiotic use for probable viral infections, and reducing infection rates will help preserve the antibiotics we have for future generations.

The future of antibiotics

Antibiotic resistance continues to spread even as society is experiencing a market failure of new antibiotic research and development (R&D). Scientific, economic, and regulatory barriers all contribute to the antibiotic market failure. Scientific solutions to rekindle R&D include finding new screening strategies to identify novel antibiotic scaffolds and transforming the way we think about treating infections, such that the goal is to disarm the pathogen without killing it or modulate the host response to the organism without targeting the organism for destruction. Future economic strategies are likely to focus on ‘push’ incentives offered by public-private partnerships as well as increasing pricing by focusing development on areas of high unmet need. Such strategies can also help protect new antibiotics from overuse after marketing. Regulatory reform is needed to re-establish feasible and meaningful traditional antibiotic pathways, to create novel limited-use pathways that focus on highly resistant infections, and to harmonize regulatory standards across nations. We need new antibiotics with which to treat our patients. But we also need to protect those new antibiotics from misuse when they become available. If we want to break the cycle of resistance and change the current landscape, disruptive approaches that challenge long-standing dogma will be needed.

White paper: recommendations on the conduct of superiority and organism-specific clinical trials of antibacterial agents for the treatment of infections caused by drug-resistant bacterial pathogens

There is a critical need for new pathways to develop antibacterial agents to treat life-threatening infections caused by highly resistant bacteria. Traditionally, antibacterial agents have been studied in noninferiority clinical trials that focus on one site of infection (eg, pneumonia, intra-abdominal infection). Conduct of superiority trials for infections caused by highly antibiotic-resistant bacteria represents a new, and as yet, untested paradigm for antibacterial drug development. We sought to define feasible trial designs of antibacterial agents that could enable conduct of superiority and organism-specific clinical trials. These recommendations are the results of several years of active dialogue among the white paper's drafters as well as external collaborators and regulatory officials. Our goal is to facilitate conduct of new types of antibacterial clinical trials to enable development and ultimately approval of critically needed new antibacterial agents.