Donald R. VanDevanter

Decade-long bacterial community dynamics in cystic fibrosis airways

The structure and dynamics of bacterial communities in the airways of persons with cystic fibrosis (CF) remain largely unknown. We characterized the bacterial communities in 126 sputum samples representing serial collections spanning 8–9 y from six age-matched male CF patients. Sputum DNA was analyzed by bar-coded pyrosequencing of the V3–V5 hypervariable region of the 16S rRNA gene, defining 662 operational taxonomic units (OTUs) from >633,000 sequences. Bacterial community diversity decreased significantly over time in patients with typically progressive lung disease but remained relatively stable in patients with a mild lung disease phenotype. Antibiotic use, rather than patient age or lung function, was the primary driver of decreasing diversity. Interpatient variability in community structure exceeded intrapatient variability in serial samples. Antibiotic treatment was associated with pronounced shifts in community structure, but communities showed both short- and long-term resilience after antibiotic perturbation. There was a positive correlation between OTU occurrence and relative abundance, with a small number of persistent OTUs accounting for the greatest abundance. Significant changes in community structure, diversity, or total bacterial density at the time of pulmonary exacerbation were not observed. Despite decreasing community diversity in patients with progressive disease, total bacterial density remained relatively stable over time. These findings show the critical relationship between airway bacterial community structure, disease stage, and clinical state at the time of sample collection. These features are the key parameters with which to assess the complex ecology of the CF airway.

Risk factors for rate of decline in FEV1 in adults with cystic fibrosis.

BACKGROUND Previously we assessed risk factors for FEV(1) decline in children and adolescents using the Epidemiologic Study of Cystic Fibrosis (J Pediatr 2007;151:134-139); the current study assessed risk factors in adults. METHODS Risk factors for FEV(1) decline over 3-5.5 years for ages 18-24 and ≥25 years were assessed using mixed-model regression. RESULTS Mean rates of FEV(1) decline (% predicted/year) were -1.92 for ages 18-24y (n=2793) and -1.45 for ages ≥25y (n=1368). For the 18-24y group, B. cepacia, pancreatic enzyme use, multidrug-resistant P. aeruginosa, cough, mucoid P. aeruginosa, and female sex predicted greater decline; low baseline FEV(1) and sinusitis predicted less decline. For the ≥25y group, only pancreatic enzyme use predicted greater decline; low baseline FEV(1) and sinusitis predicted less decline. CONCLUSIONS Risk factors for FEV(1) decline in adults <25 years are similar to those previously identified in children and adolescents; older adults had few statistically significant risk factors.

Anti-PcrV antibody in cystic fibrosis: A novel approach targeting Pseudomonas aeruginosa airway infection

Pseudomonas aeruginosa (Pa) airway infection is associated with increased morbidity and mortality in cystic fibrosis (CF). The type III secretion system is one of the factors responsible for the increased virulence and pro‐inflammatory effects of Pa. KB001 is a PEGylated, recombinant, anti‐Pseudomonas‐PcrV antibody Fab′ fragment that blocks the function of Pa TTSS. We studied the safety, pharmacokinetic (PK), and pharmacodynamic properties of KB001 in CF subjects with chronic Pa infection. Twenty‐seven eligible CF subjects (≥12 years of age, FEV1 ≥40% of predicted, and sputum Pa density >105 CFU/g) received a single intravenous dose of KB001 (3 mg/kg or 10 mg/kg) or placebo. Safety, PK, Pa density, clinical outcomes, and inflammatory markers were assessed. KB001 had an acceptable safety profile and a mean serum half‐life of 11.9 days. All subjects had Pa TTSS expression in sputum. There were no significant differences between KB001 and placebo for changes in Pa density, symptoms, or spirometry after a single dose. However, compared to baseline, at Day 28 there was a trend towards a dose‐dependent reduction in sputum myeloperoxidase, IL‐1, and IL‐8, and there were significant overall differences in change in sputum neutrophil elastase and neutrophil counts favoring the KB001 10 mg/kg group versus placebo (−0.61 log10 and −0.63 log10, respectively; P < 0.05). These results support targeting Pa TTSS with KB001 as a nonantibiotic strategy to reduce airway inflammation and damage in CF patients with chronic Pa infection. Repeat‐dosing studies are necessary to evaluate the durability of the anti‐inflammatory effects and how that may translate into clinical benefit. (NCT00638365) Pediatr Pulmonol. 2014; 49:650–658.

Oral, inhaled, and intravenous antibiotic choice for treating pulmonary exacerbations in cystic fibrosis.

Patients with cystic fibrosis (CF) experience frequent pulmonary exacerbations (PExs). Clinicians manage these episodes of worsening signs and symptoms in a variety of ways.

Trends in the use of routine therapies in cystic fibrosis: 1995–2005

Many therapies are used to treat manifestations of cystic fibrosis (CF). Trends in routine therapy use in Epidemiologic Study of Cystic Fibrosis patients were studied from 1995 to 2005. Patients (15,087) were assessed in 1995; 12,778 in 2005. Observed differences in therapy use of ≥2% were statistically significant at P < 0.001. Comparing the 1995 and 2005 populations, mean age was 13.9 versus 15.5 years; weight‐for‐age percentile was 30.3 versus 36.9; and mean forced expiratory volume in 1 sec (FEV1) was 73.7% (n = 7065) versus 78.7% (n = 7867) predicted. Use of several therapies increased, including airway clearance (69.9–89.6%), inhaled bronchodilators (72.0–84.0%), dornase alfa (44.8–67.2%), inhaled corticosteroids (16.0–49.3%), inhaled antibiotics (6.5–43.1%), oral nutritional supplements (18.3–24.5%), and insulin/oral hypoglycemic agents (4.9–10.2%). Use of mast cell stabilizers (from 22.0% to 5.3%) and oral bronchodilators (from 10.4% to 1.5%) decreased. Less dramatic changes occurred for pancreatic enzymes (92.6–91.0%), oral nonquinolone antibiotics (44.7–39.8%), oral corticosteroids (7.8–5.2%), mucolytics (4.4–2.5%), NSAIDs/high‐dose ibuprofen (3.6–3.3%), enteral nutrition (5.2% vs. 8.2%), and oxygen (4.7–4.5%). Therapies not tracked in 1995 were evident in 2005, including oral macrolide antibiotics (33.8%), leukotriene inhibitors/antagonists (10.8%), and inhaled hypertonic saline (2.6%). Routine therapies were generally used more often by older patients and those with lower FEV1. Notable increases in use of therapies, particularly of inhaled therapies, suggest that overall patient treatment burden must have risen correspondingly. Pediatr Pulmonol. 2010;45:1167–1172.

Assessing time to pulmonary function benefit following antibiotic treatment of acute cystic fibrosis exacerbations

BackgroundCystic Fibrosis (CF) is a life-shortening genetic disease in which ~80% of deaths result from loss of lung function linked to inflammation due to chronic bacterial infection (principally Pseudomonas aeruginosa). Pulmonary exacerbations (intermittent episodes during which symptoms of lung infection increase and lung function decreases) can cause substantial resource utilization, morbidity, and irreversible loss of lung function. Intravenous antibiotic treatment to reduce exacerbation symptoms is standard management practice. However, no prospective studies have identified an optimal antibiotic treatment duration and this lack of objective data has been identified as an area of concern and interest.MethodsWe have retrospectively analyzed pulmonary function response data (as forced expiratory volume in one second; FEV1) from a previous blinded controlled CF exacerbation management study of intravenous ceftazidime/tobramycin and meropenem/tobramycin in which spirometry was conducted daily to assess the time course of pulmonary function response.ResultsNinety-five patients in the study received antibiotics for at least 4 days and were included in our analyses. Patients received antibiotics for an average of 12.6 days (median = 13, SD = 3.2 days), with a range of 4 to 27 days. No significant differences were observed in mean or median treatment durations as functions of either treatment group or baseline lung disease stage. Average time from initiation of antibiotic treatment to highest observed FEV1 was 8.7 days (median = 10, SD = 4.0 days), with a range of zero to 19 days. Patients were treated an average of 3.9 days beyond the day of peak FEV1 (median = 3, SD = 3.8 days), with 89 patients (93.7%) experiencing their peak FEV1 improvement within 13 days. There were no differences in mean or median times to peak FEV1 as a function of treatment group, although the magnitude of FEV1 improvement differed between groups.ConclusionsOur results suggest that antibiotic response to exacerbation as assessed by pulmonary function is essentially complete within 2 weeks of treatment initiation and relatively independent of the magnitude of pulmonary function response observed.

Tobramycin administered by the TOBI(®) Podhaler(®) for persons with cystic fibrosis: a review.

From its introduction, the antibiotic tobramycin has been an important tool in the management of persons with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa lung infections. Initially an intravenous rescue treatment for pulmonary exacerbations, tobramycin delivered by inhalation has become a mainstay of chronic suppressive CF infection management. Platforms for tobramycin aerosol delivery have steadily improved, with increased lung deposition complimented by decreased device complexities, loaded tobramycin doses, delivery times, and treatment burdens. Most recently, a unique tobramycin inhalation powder (TIP) formulation with a portable delivery system, the TOBI® Podhaler® (Novartis AG, Basel, Switzerland) has been developed and approved in Europe, Canada, and Chile. Four capsules, each containing 28 mg of TIP are successively pierced and inhaled via the T-326 Dry Powder Inhaler Device (Novartis AG, Basel, Switzerland). No external power source is required to deliver an efficacious tobramycin dose in minutes. By comparison, tobramycin inhalation solution (TIS) (TOBI®; Novartis), is delivered by LC® Plus (PARI Respiratory Equipment Inc, Midlothian, VA) jet nebulizer powered by an air compressor over 15–20 minutes. Comparative pharmacokinetics, safety, and efficacy studies of TIS and TIP in CF subjects with P. aeruginosa ≥ 6 years old demonstrate that: tobramycin lung deposition with 112 mg TIP is comparable to that attained with 300 mg TIS, TIP is more effective than placebo and not inferior to TIS with respect to pulmonary function benefit, and TIP has significantly faster treatment times and achieves higher patient satisfaction than TIS. TIP is associated with an increased frequency of mild to moderate local adverse events (cough, dysphonia, and dysgeusia) compared with TIS, however, these become less frequent as subjects gain TIP experience. These results suggest that the TOBI Podhaler may better meet the needs of many CF patients and families by reducing treatment time and complexity and improving patient satisfaction compared with TIS.

A phase 3, open-label, randomized trial to evaluate the safety and efficacy of levofloxacin inhalation solution (APT-1026) versus tobramycin inhalation solution in stable cystic fibrosis patients

BACKGROUND Inhaled antibiotics are standard of care for persons with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa airway infection. APT-1026 (levofloxacin inhalation solution, LIS) is fluoroquinolone in development. We compared the safety and efficacy of LIS to tobramycin inhalation solution (TIS) in persons ≥12 years old with CF and chronic P. aeruginosa infection. METHODS This multinational, randomized (2:1), non-inferiority study compared LIS and TIS over three 28-day on/off cycles. Day 28 FEV(1) % predicted relative change was the primary endpoint. Time to exacerbation and patient-reported quality of life were among secondary endpoints. RESULTS Baseline demographics for 282 subjects were comparable. Non-inferiority was demonstrated (1.86% predicted mean FEV(1) difference [95% CI -0.66 to 4.39%]). LIS was well-tolerated, with dysgeusia (taste distortion) as the most frequent adverse event. CONCLUSIONS LIS is a safe and effective therapy for the management of CF patients with chronic P. aeruginosa infection.

Characterizing aggressiveness and predicting future progression of CF lung disease

Cystic fibrosis (CF) is a life-shortening genetic disease characterized by variability in age of death that is largely due to variability in rate of progression of lung disease, the primary cause of mortality. Recognizing which individuals have more aggressive disease phenotypes and predicting their risk of immediate lung disease progression is a critical step in managing CF lung disease and extending the life expectancy of CF patients. Studies using observational CF patient registries have yielded useful methods for predicting future rate of disease progression and can be used to determine the impact that chronic pulmonary therapies have on slowing rate of lung function decline.

Pulmonary outcome prediction (POP) tools for cystic fibrosis patients

Loss of lung function in patients with cystic fibrosis (CF) is associated with increased mortality and varies between individuals and over time. Predicting this decline could improve patient management.