Evidence-Based Study Design for Hospital-Acquired Bacterial Pneumonia and Ventilator-Associated Bacterial Pneumonia.

BACKGROUND: The US Food and Drug Administration solicited evidence-based recommendations to improve guidance for studies of hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP). METHODS: We analyzed 7 HABP/VABP datasets to explore novel noninferiority study endpoints and designs, focusing on alternatives to all-cause mortality (ACM). RESULTS: ACM at day 28 differed for ventilated HABP (27.8%), VABP (18.0%), and nonventilated HABP (14.5%). A "mortality-plus" (ACM+) composite endpoint was constructed by combining ACM with patient-relevant, infection-related adverse events from the Medical Dictionary for Regulatory Activities toxic/septic shock standardized query. The ACM+ rate was 3-10 percentage points above that of ACM across the studies and treatment groups. Predictors of higher ACM/ACM+ rates included older age and elevated acute physiology and chronic health evaluation (APACHE) II score. Only patients in the nonventilated HABP group were able to report pneumonia symptom changes. CONCLUSIONS: If disease groups and patient characteristics in future studies produce an ACM rate so low (<10%-15%) that a fixed noninferiority margin of 10% cannot be justified (requiring an odds ratio analysis), an ACM+ endpoint could lower sample size. Enrichment of studies with patients with a higher severity of illness would increase ACM. Data on symptom resolution in nonventilated HABP support development of a patient-reported outcome instrument.

The Infectious Diseases Society of America's 10 × '20 Initiative (10 New Systemic Antibacterial Agents US Food and Drug Administration Approved by 2020): Is 20 × '20 a Possibility?

BACKGROUND: Infections caused by antibiotic-resistant bacteria, including carbapenem-resistant Enterobacteriaceae, have increased in frequency, resulting in significant patient morbidity and mortality. The Infectious Diseases Society of America continues to propose legislative, regulatory, and funding solutions to address this escalating crisis. This report updates the status of development and approval of systemic antibiotics in the United States as of late 2018. METHODS: We performed a review of the published literature and on-line clinical trials registry at www.clinicaltrials.gov to identify new systemically acting orally and/or intravenously administered antibiotic drug candidates in the development pipeline, as well as agents approved by the US Food and Drug Administration since 2012. RESULTS: Since our 2013 pipeline status report, the number of new antibiotics annually approved for marketing in the United States has reversed its previous decline, likely influenced by new financial incentives and increased regulatory flexibility. Although our survey demonstrates progress in development of new antibacterial drugs that target infections caused by resistant bacterial pathogens, the majority of recently approved agents have been modifications of existing chemical classes of antibiotics, rather than new chemical classes. Furthermore, larger pharmaceutical companies continue to abandon the field, and smaller companies face financial difficulties as a consequence. CONCLUSIONS: Unfortunately, if 20 × '20 is achieved due to efforts embarked upon in decades past, it could mark the apex of antibiotic drug development for years to come. Without increased regulatory, governmental, industry, and scientific support and collaboration, durable solutions to the clinical, regulatory, and economic problems posed by bacterial multidrug resistance will not be found.

Efficacy and Safety of Intravenous-to-oral Lefamulin, a Pleuromutilin Antibiotic, for the Treatment of Community-acquired Bacterial Pneumonia: The Phase III Lefamulin Evaluation Against Pneumonia (LEAP 1) Trial.

BACKGROUND: Lefamulin, a pleuromutilin antibiotic, is active against pathogens commonly causing community-acquired bacterial pneumonia (CABP). The Lefamulin Evaluation Against Pneumonia (LEAP 1) study was a global noninferiority trial to evaluate the efficacy and safety of lefamulin for the treatment of CABP. METHODS: In this double-blind study, adults with CABP of Pneumonia Outcomes Research Team risk class ≥III were randomized 1:1 to receive lefamulin at 150 mg intravenously (IV) every 12 hours or moxifloxacin at 400 mg IV every 24 hours. After 6 doses, patients could be switched to an oral study drug if prespecified improvement criteria were met. If methicillin-resistant Staphylococcus aureus was suspected, either linezolid or placebo was added to moxifloxacin or lefamulin, respectively. The US Food and Drug Administration primary endpoint was an early clinical response (ECR) 96 ± 24 hours after the first dose of the study drug in the intent-to-treat (ITT) population (noninferiority margin, 12.5%). The European Medicines Agency co-primary endpoints were an investigator assessment of clinical response (IACR) 5-10 days after the last dose of the study drug in the modified ITT (mITT) and clinically evaluable (CE) populations (noninferiority margin, 10%). RESULTS: There were 551 patients randomized (n = 276 lefamulin; n = 275 moxifloxacin). Lefamulin was noninferior to moxifloxacin for ECR (87.3% vs 90.2%, respectively; difference -2.9%, 95% confidence interval [CI] g -8.5 to 2.8) and IACR (mITT, 81.7% vs 84.2%, respectively; difference -2.6%, 95% CI -8.9 to 3.9; CE, 86.9% vs 89.4%, respectively; difference -2.5%, 95% CI -8.4 to 3.4). Rates of study drug discontinuation due to treatment-emergent adverse events were 2.9% for lefamulin and 4.4% for moxifloxacin. CONCLUSIONS: Lefamulin was noninferior to moxifloxacin for the primary efficacy endpoints and was generally safe and well tolerated. CLINICAL TRIALS REGISTRATION: NCT02559310.

Elaboration of Consensus Clinical Endpoints to Evaluate Antimicrobial Treatment Efficacy in Future Hospital-acquired/Ventilator-associated Bacterial Pneumonia Clinical Trials.

BACKGROUND: Randomized clinical trials (RCTs) in hospital-acquired and ventilator-associated bacterial pneumonia (HABP and VABP, respectively) are important for the evaluation of new antimicrobials. However, the heterogeneity in endpoints used in RCTs evaluating treatment of HABP/VABP may puzzle clinicians. The aim of this work was to reach a consensus on clinical endpoints to consider in future clinical trials evaluating antimicrobial treatment efficacy for HABP/VABP. METHODS: Twenty-six international experts from intensive care, infectious diseases, and the pharmaceutical industry were polled using the Delphi method. RESULTS: The panel recommended a hierarchical composite endpoint including, by priority order, (1) survival at day 28, (2) mechanical ventilation-free days through day 28, and (3) clinical cure between study days 7 and 10 for VABP; and (1) survival (day 28) and (2) clinical cure (days 7-10) for HABP. Clinical cure was defined as the combination of resolution of signs and symptoms present at enrollment and improvement or lack of progression of radiological signs. More than 70% of the experts agreed to assess survival and mechanical ventilation-free days though day 28, and clinical cure between day 7 and day 10 after treatment initiation. Finally, the hierarchical order of endpoint components was reached after 3 Delphi rounds (72% agreement). CONCLUSIONS: We provide a multinational expert consensus on separate hierarchical composite endpoints for VABP and HABP, and on a definition of clinical cure that could be considered for use in future HABP/VABP clinical trials.

Clostridium difficile Infection-Daily Symptoms (CDI-DaySyms™) questionnaire: psychometric characteristics and responder thresholds.

BACKGROUND: The purpose of the current study was to determine the final content validation, psychometric characteristics, clinically meaningful improvement, and responder thresholds of the Clostridium difficile infection (CDI)-Daily Symptoms (CDI-DaySyms™) patient-reported outcome (PRO) questionnaire. METHODS: This validation study was part of two phase III studies (NCT01987895 and NCT01983683) conducted in patients with mild-to-moderate or severe CDI who completed the CDI-DaySyms™ daily throughout the treatment period. The questionnaire was evaluated in three stages: final PRO item content validation (Stage I); psychometric evaluation of reliability and construct validity (Stage II); and determination of clinically meaningful improvement and responder thresholds using distribution-based methods (Stage III). RESULTS: The analysis included 168 patients. Most patients were female and Caucasian with mild-to-moderate CDI. The mean age was 57.1 years. Initial item analysis supported by confirmatory factor analysis demonstrated the relevance of 10 items grouped into three distinct domains (Diarrhea Symptoms, Abdominal Symptoms, and Systemic/Other Symptoms). Domain scores demonstrated acceptable internal consistency and test-retest reliability, were sensitive to change, and correlated in expected directions with other relevant symptom and disease-severity measures. Responder thresholds were defined as score changes of - 1.00, - 0.80, and - 0.70 in the Diarrhea Symptoms, Abdominal Symptoms, and Systemic/Other Symptoms domains, respectively. CONCLUSIONS: The CDI-DaySyms™ is a valid measure of patient-reported CDI symptoms, with good measurement properties, which supports its utility as an endpoint in clinical studies. Further studies confirming responder thresholds based on anchor-based methods are required. TRIAL REGISTRATION: NCT01987895 , registered November 20, 2013; NCT01983683 , registered November 14, 2013.

Evolution and current status of United States Food and Drug Administration and European Medicines Agency regulatory guidance for studies of nosocomial pneumonia.

PURPOSE OF REVIEW: Regulatory guidance for design, conduct and analysis of studies of nosocomial pneumonia, including ventilator-associated pneumonia, has undergone substantial evolution over the past three decades. This review summarizes this evolutionary process and the current status of guidance. RECENT FINDINGS: The US Food and Drug Administration and the European Medicines Agency have taken different approaches to defining endpoints for studies of nosocomial pneumonia, especially with regard to the primary endpoint. Both agencies accept a noninferiority design. Independent efforts to develop new endpoints and bridge existing discordances have been fruitful. SUMMARY: Transatlantic differences in the approach to study of nosocomial pneumonia complicate study design and analysis, but they will hopefully be resolved in future iterations of regulatory agency guidance.

The CDI-DaySyms: Content Development of a New Patient-Reported Outcome Questionnaire for Symptoms of Clostridium difficile Infection.

OBJECTIVES: To develop a patient-reported outcome (PRO) questionnaire for symptoms of Clostridium difficile infection (CDI) following the US Food and Drug Administration PRO guidelines. METHODS: Patients' experiences of CDI symptoms were elicited in open-ended discussions with patients and nurses at five US sites (stage 1). A draft PRO measure was developed after demonstration of concept saturation. Two rounds of cognitive interviews were conducted with patients at three US sites (stage 2), with revision of the draft measure after each round. All patients were 18 years or older, with confirmed CDI. The study was conducted with input from a panel of five CDI experts in Europe and North America. RESULTS: Stage 1 included interviews with 18 patients and supplementary interviews with 6 nurses; 16 additional patients were interviewed in stage 2. Patients were representative of the general CDI population and were diverse in age, sex, and disease severity. Concept saturation was reached in stage 1. Items were organized in a draft conceptual framework with five hypothesized domains: diarrhea, abdominal discomfort, tiredness, lightheadedness, and other symptoms. Stage 2 demonstrated initial content validity of the 13-item draft daily diary (CDI-DaySyms). Participants reported that the questions were clear, relevant, and comprehensive. They were able to use the instructions to complete the diary correctly and considered the 24-hour recall period appropriate. CONCLUSIONS: The CDI-DaySyms captures symptoms relevant to patients undergoing CDI, demonstrating initial content validity. Final content and psychometric validity are being evaluated in a substudy comprising patients from two ongoing international clinical trials (ClinicalTrials.gov identifiers NCT01987895 and NCT01983683).

Progress in the Fight Against Multidrug-Resistant Bacteria 2005-2016: Modern Noninferiority Trial Designs Enable Antibiotic Development in Advance of Epidemic Bacterial Resistance.

From a public health perspective, new antibacterial agents should be evaluated and approved for use before widespread resistance to existing agents emerges. However, for multidrug-resistant pathogens, demonstration of superior efficacy of a new agent over a current standard-of-care agent is routinely feasible only when epidemic spread of these dangerous organisms has already occurred. One solution to enable proactive drug development is to evaluate new antibiotics with improved in vitro activity against MDR pathogens using recently updated guidelines for active control, noninferiority trials of selected severe infections caused by more susceptible pathogens. Such trials are feasible because they enroll patients with infections due to pathogens with a "usual drug resistance" phenotype that will be responsive to widely registered standard-of-care comparator antibiotics. Such anticipatory drug development has constructively reshaped the antibiotic pipeline and offers the best chance of making safe and efficacious antibiotics available to the public ahead of epidemic resistance.

Once-weekly dalbavancin versus daily conventional therapy for skin infection.

BACKGROUND: Dalbavancin, a lipoglycopeptide antibiotic agent that is active against gram-positive pathogens, has a long plasma half-life, allowing for once-weekly dosing. DISCOVER 1 and DISCOVER 2 were identically designed noninferiority trials of dalbavancin for the treatment of acute bacterial skin and skin-structure infection. METHODS: We randomly assigned patients to receive dalbavancin intravenously on days 1 and 8 or vancomycin intravenously for at least 3 days with the option to switch to oral linezolid to complete 10 to 14 days of therapy. The primary end point, early clinical response, required the cessation of spread of infection-related erythema and the absence of fever at 48 to 72 hours. Secondary end points at the end of therapy included clinical status and investigator's assessment of outcome. RESULTS: Analysis of the primary end point showed noninferiority of dalbavancin in both DISCOVER 1 and DISCOVER 2. In the pooled analysis, 525 of 659 patients (79.7%) in the dalbavancin group and 521 of 653 (79.8%) in the vancomycin-linezolid group had an early clinical response indicating treatment success (weighted difference, -0.1 percentage point; 95% confidence interval, -4.5 to 4.2). The outcomes were similar in the analyses by study and the pooled analyses of clinical status at the end of therapy and the investigator's assessment of outcome. For patients infected with Staphylococcus aureus, including methicillin-resistant S. aureus, clinical success was seen in 90.6% of the patients treated with dalbavancin and 93.8% of those treated with vancomycin-linezolid. Adverse events and study days with an adverse event were less frequent in the dalbavancin group than in the vancomycin-linezolid group. The most common treatment-related adverse events in either group were nausea, diarrhea, and pruritus. CONCLUSIONS: Once-weekly intravenous dalbavancin was not inferior to twice-daily intravenous vancomycin followed by oral linezolid for the treatment of acute bacterial skin and skin-structure infection. (Funded by Durata Therapeutics; DISCOVER 1 and DISCOVER 2 ClinicalTrials.gov numbers, NCT01339091 and NCT01431339.).

Developing Outcomes Assessments as Endpoints for Registrational Clinical Trials of Antibacterial Drugs: 2015 Update From the Biomarkers Consortium of the Foundation for the National Institutes of Health.

One important component in determining the benefits and harms of medical interventions is the use of well-defined and reliable outcome assessments as endpoints in clinical trials. Improving endpoints can better define patient benefits, allowing more accurate assessment of drug efficacy and more informed benefit-vs-risk decisions; another potential plus is facilitating efficient trial design. Since our first report in 2012, 2 Foundation for the National Institutes of Health Biomarkers Consortium Project Teams have continued to develop outcome assessments for potential uses as endpoints in registrational clinical trials of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. In addition, the teams have initiated similar work in the indications of hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia. This report provides an update on progress to date in these 4 diseases.

In Vitro Activity of Lefamulin Tested against Streptococcus pneumoniae with Defined Serotypes, Including Multidrug-Resistant Isolates Causing Lower Respiratory Tract Infections in the United States.

Lefamulin was evaluated against various Streptococcus pneumoniae serotypes that were collected from adults with lower respiratory tract infections. Lefamulin exhibited MIC50 and MIC90 values of 0.12 and 0.25 µg/ml, respectively, against the entire collection (n = 822). Similar results were obtained for lefamulin against each of the most common serotypes as well as against multidrug-resistant isolates and strains that are nonsusceptible to ceftriaxone or erythromycin. These data support the clinical development of lefamulin for the treatment of community-acquired respiratory tract infections.

Multicenter, Double-Blind, Randomized, Phase 2 Study Evaluating the Novel Antibiotic Cadazolid in Patients with Clostridium difficile Infection.

Cadazolid, a novel fluoroquinolone-oxazolidinone antibiotic, exhibits potent in vitro activity against Clostridium difficile, including the epidemic BI/NAP1/027 strain. This multicenter, randomized, double-blind, active reference group, phase 2 study evaluated the efficacy and safety of oral cadazolid in treatment of adult patients with C. difficile infection (CDI). Eligible patients with first occurrence/first recurrence of CDI were randomized 1:1:1:1 to 250, 500, or 1,000 mg cadazolid twice daily (BID) or oral 125 mg vancomycin four times daily (QID) for 10 days. The primary endpoint was clinical cure at test of cure (48 ± 24 h after the end of treatment; modified intent-to-treat population), defined as resolution of diarrhea with no further CDI treatment required. Secondary endpoints included recurrence rate, sustained clinical response (clinical cure without recurrence), and time to diarrhea resolution. Of 84 patients enrolled, 20, 22, 20, and 22 received 250, 500, or 1,000 mg cadazolid BID or 125 mg vancomycin QID, respectively. The primary endpoint was achieved in 76.5% (80% confidence interval [CI], 58.4, 89.3), 80.0% (63.9, 91.0), 68.4% (51.1, 82.5), and 68.2% (52.3, 81.3) of patients, respectively. There was no evidence of a cadazolid dosage-dependent response. Each dosage of cadazolid resulted in a lower recurrence rate than with vancomycin (18.2 to 25.0% versus 50%). Consequently, higher sustained clinical response rates were observed with cadazolid (46.7 to 60.0%) than with vancomycin (33.3%). The times to diarrhea resolution were similar for cadazolid and vancomycin. Cadazolid was well tolerated, with no safety signal observed. The results of this phase 2 study support further clinical development of cadazolid. (This study has been registered in the United States at ClinicalTrials.gov under registration no. NCT01222702 and in Europe with the European Medicines Agency under registration no. EUDRA-CT 2010-020941-29.).

10 x '20 Progress--development of new drugs active against gram-negative bacilli: an update from the Infectious Diseases Society of America.

Infections caused by antibiotic-resistant bacteria, especially the "ESKAPE" pathogens, continue to increase in frequency and cause significant morbidity and mortality. New antimicrobial agents are greatly needed to treat infections caused by gram-negative bacilli (GNB) resistant to currently available agents. The Infectious Diseases Society of America (IDSA) continues to propose legislative, regulatory, and funding solutions to this continuing crisis. The current report updates the status of development and approval of systemic antibiotics in the United States as of early 2013. Only 2 new antibiotics have been approved since IDSA's 2009 pipeline status report, and the number of new antibiotics annually approved for marketing in the United States continues to decline. We identified 7 drugs in clinical development for treatment of infections caused by resistant GNB. None of these agents was included in our 2009 list of antibacterial compounds in phase 2 or later development, but unfortunately none addresses the entire spectrum of clinically relevant GNB resistance. Our survey demonstrates some progress in development of new antibacterial drugs that target infections caused by resistant GNB, but progress remains alarmingly elusive. IDSA stresses our conviction that the antibiotic pipeline problem can be solved by the collaboration of global leaders to develop creative incentives that will stimulate new antibacterial research and development. Our aim is the creation of a sustainable global antibacterial drug research and development enterprise with the power in the short term to develop 10 new, safe, and efficacious systemically administered antibiotics by 2020 as called for in IDSA's "10 × '20 Initiative."

Prospective study of the Wilson severity-of-illness scoring system for complicated skin and skin structure infections.

Wilson et al. (Am. J. Surg. 185:369-375, 2003) developed a disease severity classification system for use in complicated skin and skin structure infections (cSSSI). Two phase 3 trials of ceftaroline fosamil in cSSSI provided the opportunity to evaluate the association between Wilson Severity Risk Class and clinical cure rates. Our analyses did not confirm that an association exists between Wilson Severity Risk Class and clinical cure rate and, thus, did not validate its predictive utility.