Michael W. Konstan

A CFTR Potentiator in Patients with Cystic Fibrosis and the G551D Mutation

BACKGROUND Increasing the activity of defective cystic fibrosis transmembrane conductance regulator (CFTR) protein is a potential treatment for cystic fibrosis. METHODS We conducted a randomized, double-blind, placebo-controlled trial to evaluate ivacaftor (VX-770), a CFTR potentiator, in subjects 12 years of age or older with cystic fibrosis and at least one G551D-CFTR mutation. Subjects were randomly assigned to receive 150 mg of ivacaftor every 12 hours (84 subjects, of whom 83 received at least one dose) or placebo (83, of whom 78 received at least one dose) for 48 weeks. The primary end point was the estimated mean change from baseline through week 24 in the percent of predicted forced expiratory volume in 1 second (FEV(1)). RESULTS The change from baseline through week 24 in the percent of predicted FEV(1) was greater by 10.6 percentage points in the ivacaftor group than in the placebo group (P<0.001). Effects on pulmonary function were noted by 2 weeks, and a significant treatment effect was maintained through week 48. Subjects receiving ivacaftor were 55% less likely to have a pulmonary exacerbation than were patients receiving placebo, through week 48 (P<0.001). In addition, through week 48, subjects in the ivacaftor group scored 8.6 points higher than did subjects in the placebo group on the respiratory-symptoms domain of the Cystic Fibrosis Questionnaire-revised instrument (a 100-point scale, with higher numbers indicating a lower effect of symptoms on the patients quality of life) (P<0.001). By 48 weeks, patients treated with ivacaftor had gained, on average, 2.7 kg more weight than had patients receiving placebo (P<0.001). The change from baseline through week 48 in the concentration of sweat chloride, a measure of CFTR activity, with ivacaftor as compared with placebo was -48.1 mmol per liter (P<0.001). The incidence of adverse events was similar with ivacaftor and placebo, with a lower proportion of serious adverse events with ivacaftor than with placebo (24% vs. 42%). CONCLUSIONS Ivacaftor was associated with improvements in lung function at 2 weeks that were sustained through 48 weeks. Substantial improvements were also observed in the risk of pulmonary exacerbations, patient-reported respiratory symptoms, weight, and concentration of sweat chloride. (Funded by Vertex Pharmaceuticals and others; VX08-770-102 ClinicalTrials.gov number, NCT00909532.).

Effect of High-Dose Ibuprofen in Patients with Cystic Fibrosis

BACKGROUND Since the inflammatory response to chronic infection contributes to lung destruction in patients with cystic fibrosis, we hypothesized that anti-inflammatory therapy might slow the progression of lung disease. METHODS In a double-blind trial, 85 patients, 5 to 39 years of age, with mild lung disease (forced expiratory volume in one second [FEV1], > or = 60 percent of the predicted value) were randomly assigned to receive ibuprofen or placebo orally twice daily for four years. Doses were adjusted individually to achieve peak plasma concentrations of 50 to 100 micrograms per milliliter. Changes in pulmonary function, the percentage of ideal body weight, the chest-radiograph score, and the frequency of hospitalization were assessed. RESULTS Patients randomly assigned to ibuprofen had a slower annual rate of change in FEV1 than the patients assigned to placebo (mean [+/- SE] slope, -2.17 +/- 0.57 percent vs. -3.60 +/- 0.55 percent in the placebo group; P = 0.02), and weight (as a percentage of ideal body weight) was better maintained in the former group (P = 0.02). Among the patients who took ibuprofen for four years and had at least a 70 percent rate of compliance, the annual rate of change in FEV1 was even slower (-1.48 +/- 0.69 percent vs. -3.57 +/- 0.65 percent in the placebo group, P = 0.03), and this group of patients also had a significantly slower rate of decline in forced vital capacity, the percentage of ideal body weight, and the chest-radiograph score. There was no significant difference between the ibuprofen and placebo groups in the frequency of hospitalization. One patient was withdrawn from the study because of conjunctivitis, and one because of epistaxis related to ibuprofen. CONCLUSIONS In patients with cystic fibrosis and mild lung disease, high-dose ibuprofen, taken consistently for four years, significantly slows the progression of the lung disease without serious adverse effects.

Effect of VX-770 in persons with cystic fibrosis and the G551D-CFTR mutation

BACKGROUND A new approach in the treatment of cystic fibrosis involves improving the function of mutant cystic fibrosis transmembrane conductance regulator (CFTR). VX-770, a CFTR potentiator, has been shown to increase the activity of wild-type and defective cell-surface CFTR in vitro. METHODS We randomly assigned 39 adults with cystic fibrosis and at least one G551D-CFTR allele to receive oral VX-770 every 12 hours at a dose of 25, 75, or 150 mg or placebo for 14 days (in part 1 of the study) or VX-770 every 12 hours at a dose of 150 or 250 mg or placebo for 28 days (in part 2 of the study). RESULTS At day 28, in the group of subjects who received 150 mg of VX-770, the median change in the nasal potential difference (in response to the administration of a chloride-free isoproterenol solution) from baseline was -3.5 mV (range, -8.3 to 0.5; P=0.02 for the within-subject comparison, P=0.13 vs. placebo), and the median change in the level of sweat chloride was -59.5 mmol per liter (range, -66.0 to -19.0; P=0.008 within-subject, P=0.02 vs. placebo). The median change from baseline in the percent of predicted forced expiratory volume in 1 second was 8.7% (range, 2.3 to 31.3; P=0.008 for the within-subject comparison, P=0.56 vs. placebo). None of the subjects withdrew from the study. Six severe adverse events occurred in two subjects (diffuse macular rash in one subject and five incidents of elevated blood and urine glucose levels in one subject with diabetes). All severe adverse events resolved without the discontinuation of VX-770. CONCLUSIONS This study to evaluate the safety and adverse-event profile of VX-770 showed that VX-770 was associated with within-subject improvements in CFTR and lung function. These findings provide support for further studies of pharmacologic potentiation of CFTR as a means to treat cystic fibrosis. (Funded by Vertex Pharmaceuticals and others; ClinicalTrials.gov number, NCT00457821.).

Lumacaftor–Ivacaftor in Patients with Cystic Fibrosis Homozygous for Phe508del CFTR

BACKGROUND Cystic fibrosis is a life-limiting disease that is caused by defective or deficient cystic fibrosis transmembrane conductance regulator (CFTR) protein activity. Phe508del is the most common CFTR mutation. METHODS We conducted two phase 3, randomized, double-blind, placebo-controlled studies that were designed to assess the effects of lumacaftor (VX-809), a CFTR corrector, in combination with ivacaftor (VX-770), a CFTR potentiator, in patients 12 years of age or older who had cystic fibrosis and were homozygous for the Phe508del CFTR mutation. In both studies, patients were randomly assigned to receive either lumacaftor (600 mg once daily or 400 mg every 12 hours) in combination with ivacaftor (250 mg every 12 hours) or matched placebo for 24 weeks. The primary end point was the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV1) at week 24. RESULTS A total of 1108 patients underwent randomization and received study drug. The mean baseline FEV1 was 61% of the predicted value. In both studies, there were significant improvements in the primary end point in both lumacaftor-ivacaftor dose groups; the difference between active treatment and placebo with respect to the mean absolute improvement in the percentage of predicted FEV1 ranged from 2.6 to 4.0 percentage points (P<0.001), which corresponded to a mean relative treatment difference of 4.3 to 6.7% (P<0.001). Pooled analyses showed that the rate of pulmonary exacerbations was 30 to 39% lower in the lumacaftor-ivacaftor groups than in the placebo group; the rate of events leading to hospitalization or the use of intravenous antibiotics was lower in the lumacaftor-ivacaftor groups as well. The incidence of adverse events was generally similar in the lumacaftor-ivacaftor and placebo groups. The rate of discontinuation due to an adverse event was 4.2% among patients who received lumacaftor-ivacaftor versus 1.6% among those who received placebo. CONCLUSIONS These data show that lumacaftor in combination with ivacaftor provided a benefit for patients with cystic fibrosis homozygous for the Phe508del CFTR mutation. (Funded by Vertex Pharmaceuticals and others; TRAFFIC and TRANSPORT ClinicalTrials.gov numbers, NCT01807923 and NCT01807949.).

Results of a phase IIa study of VX-809, an investigational CFTR corrector compound, in subjects with cystic fibrosis homozygous for the F508del-CFTR mutation

Background VX-809, a cystic fibrosis transmembrane conductance regulator (CFTR) modulator, has been shown to increase the cell surface density of functional F508del-CFTR in vitro. Methods A randomised, double-blind, placebo-controlled study evaluated the safety, tolerability and pharmacodynamics of VX-809 in adult patients with cystic fibrosis (n=89) who were homozygous for the F508del-CFTR mutation. Subjects were randomised to one of four VX-809 28 day dose groups (25, 50, 100 and 200 mg) or matching placebo. Results The type and incidence of adverse events were similar among VX-809- and placebo-treated subjects. Respiratory events were the most commonly reported and led to discontinuation by one subject in each active treatment arm. Pharmacokinetic data supported a once-daily oral dosing regimen. Pharmacodynamic data suggested that VX-809 improved CFTR function in at least one organ (sweat gland). VX-809 reduced elevated sweat chloride values in a dose-dependent manner (p=0.0013) that was statistically significant in the 100 and 200 mg dose groups. There was no statistically significant improvement in CFTR function in the nasal epithelium as measured by nasal potential difference, nor were there statistically significant changes in lung function or patient-reported outcomes. No maturation of immature F508del-CFTR was detected in the subgroup that provided rectal biopsy specimens. Conclusions In this study, VX-809 had a similar adverse event profile to placebo for 28 days in F508del-CFTR homozygous patients, and demonstrated biological activity with positive impact on CFTR function in the sweat gland. Additional data are needed to determine how improvements detected in CFTR function secondary to VX-809 in the sweat gland relate to those measurable in the respiratory tract and to long-term measures of clinical benefit. Clinical trial number NCT00865904

Current Understanding of the Inflammatory Process in Cystic Fibrosis: Onset and Etiology

Although airway obstruction and chronic endobronchial infection have long been recognized as major factors in the pathogenesis of lung disease in cystic fibrosis (CF), only recently has it been recognized that the inflammatory process itself may be responsible in a major way for destroying the lungs. The most characteristic feature of inflammation in the CF lung is the persistent infiltration of massive numbers of neutrophils into the airways. Although neutrophils help to control infection, when present in great excess, they cause more harm than good. Major advances in our understanding of the inflammatory process in the CF lung have come from the use of bronchoscopy and bronchoalveolar lavage (BAL) to analyze the inflammatory process in patients who are relatively symptom free and/or do not regularly produce sputum. Recent BAL studies suggest that neutrophil‐rich inflammation begins very early, even in infants without clinically apparent lung disease. A number of chemoattractants from epithelial cells, macrophages, neutrophils themselves, and bacterial products contribute to the neutrophil influx. Surprisingly, some infants have inflammation even in the apparent absence of infection, leading to the speculation that inflammation may precede infection. Links between the basic defect in CF and inflammation have been postulated, with dysregulation of cytokine production and abnormal epithelial host defenses being implicated as causal factors of sustained inflammation. Regardless of the details of how this process is initiated and/or perpetuated, it has become clear that inflammation begins at a very early stage and progresses throughout life, gradually worsening and destroying the lungs. For these reasons, anti‐inflammatory therapy should be initiated in early life. Additional studies are necessary to define the optimal anti‐inflammatory drugs and regimens, and to confirm their long‐term safety and efficacy. Pediatr. Pulmonol. 1997;24:137–142.

Excessive inflammatory response of cystic fibrosis mice to bronchopulmonary infection with Pseudomonas aeruginosa.

In cystic fibrosis (CF), defective function of the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells and submucosal glands results in chronic pulmonary infection with Pseudomonas aeruginosa. The pulmonary infection incites an intense host inflammatory response, causing progressive suppurative pulmonary disease. Mouse models of CF, however, fail to develop pulmonary disease spontaneously. We examined the effects of bronchopulmonary infection on mice homozygous for the S489X mutation of the CFTR gene using an animal model of chronic Pseudomonas endobronchial infection. Slurries of sterile agarose beads or beads containing a clinical isolate of mucoid P. aeruginosa were instilled in the right lung of normal or CF mice. The mortality of CF mice inoculated with Pseudomonas-laden beads was significantly higher than that of normal animals: 82% of infected CF mice, but only 23% of normal mice, died within 10 d of infection (P = 0.023). The concentration of inflammatory mediators, including TNF-alpha, murine macrophage inflammatory protein-2, and KC/N51, in bronchoalveolar lavage fluid in CF mice 3 d after infection and before any mortality, was markedly elevated compared with normal mice. This inflammatory response also correlated with weight loss observed in both CF and normal littermates after inoculation. Thus, this model may permit examination of the relationship of bacterial infections, inflammation, and the cellular and genetic defects in CF.

Altered respiratory epithelial cell cytokine production in cystic fibrosis

BACKGROUND Reports that lung inflammation in patients with cystic fibrosis (CF) might precede infection raise the possibility that the excessive inflammatory response in lungs of patients with CF might be directly related to defects in epithelial cell cystic fibrosis transmembrane regulator. OBJECTIVE We sought to determine the relationship of epithelial cell cytokine production to CF lung disease. METHODS Immunofluorescence and cultures of freshly obtained bronchial epithelial cells and ELISA for IL-10, IL-8, and IL-6 were used to study alterations in epithelial cell cytokine production. RESULTS Fresh bronchial epithelial cells from healthy control subjects (HCs) secreted 98 +/- 20 pg/mL of the anti-inflammatory cytokine IL-10 when placed in primary culture in vitro but little or no IL-8 or IL-6. In contrast, fresh epithelial cells from patients with CF did not secrete detectable IL-10 but produced 38 +/- 17 pg/mL IL-8 and 40 +/- 17 pg/mL IL-6. These data correlated very well with the immunofluorescence data. The correlation between the immunofluorescent staining of fresh bronchial epithelial cells from both the HCs and patients with CF and the concentrations of cytokines in epithelial lining fluid suggests a reciprocal relationship between anti-inflammatory (IL-10) and proinflammatory (IL-6 and IL-8) cytokine production by the epithelial cells in HCs versus patients with CF. CONCLUSIONS Alterations in epithelial cell cytokine production in the lungs of patients with CF may contribute to the excessive local inflammation.

Association between respiratory tract methicillin-resistant Staphylococcus aureus and survival in cystic fibrosis

CONTEXT The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the respiratory tract of individuals with cystic fibrosis (CF) has increased dramatically; however, its impact on outcomes in CF is unclear. Because the time between infection with bacteria in CF and death can be decades, observational studies with long periods of follow-up are well suited to address the current gap in knowledge. OBJECTIVE To determine whether isolation of MRSA from the respiratory tract of CF patients is associated with worse survival compared with patients who never have a culture positive for MRSA. DESIGN, SETTING, AND PARTICIPANTS Cohort study of 19,833 CF patients aged 6 to 45 years seen at centers accredited by the Cystic Fibrosis Foundation in the United States. Patients entered between January 1996 and December 2006 and were followed up through December 2008. Cox regression models with time-varying covariates were used to compare survival between CF patients with and without respiratory tract MRSA. MAIN OUTCOME MEASURE Time from age at entry until age at death from any cause. RESULTS In 137,819 patient-years of observation (median, 7.3 years/patient), 2537 CF patients died and 5759 patients had MRSA detected. The mortality rate was 18.3 deaths (95% confidence interval [CI], 17.5-19.1) per 1000 patient-years in patients without MRSA and 27.7 deaths (95% CI, 25.3-30.4) per 1000 patient-years in those with MRSA. Among those with MRSA, the attributable risk percentage of death associated with MRSA was 34.0% (95% CI, 26.7%-40.4%). The unadjusted hazard ratio associated with MRSA was 1.47 (95% CI, 1.32-1.62). After adjustment for time-varying covariates associated with severity of illness, MRSA remained associated with a higher risk of death (1.27; 95% CI, 1.11-1.45). CONCLUSION Detection of MRSA in the respiratory tract of CF patients was associated with worse survival.

Safety, efficacy and convenience of tobramycin inhalation powder in cystic fibrosis patients: The EAGER trial

BACKGROUND A light-porous-particle, dry-powder formulation of tobramycin was developed, using PulmoSphere® technology, to improve airway delivery efficiency, substantially reduce delivery time, and improve patient convenience and satisfaction. We evaluated the safety, efficacy and convenience of tobramycin inhalation powder (TIP™) versus tobramycin inhalation solution (TIS, TOBI®) for treating Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients aged ≥6 years. METHODS In this open-label study, 553 patients were randomized 3:2 to TIP (total 112mg tobramycin) via the Novartis T-326 Inhaler or TIS 300mg/5mL via PARI LC® PLUS nebulizer twice daily for three treatment cycles (28 days on-drug, 28 days off-drug). Safety, efficacy, and treatment satisfaction outcomes were evaluated. RESULTS TIP was generally well-tolerated; adverse events were similar in both groups. The rate of cough suspected to be study drug related was higher in TIP-treated patients (TIP: 25.3%; TIS: 4.3%), as was the overall discontinuation rate (TIP: 26.9%; TIS: 18.2%). Increases in FEV(1)% predicted from baseline to Day 28 of Cycle 3 were similar between groups; the mean reduction in sputum P. aeruginosa density (log(10) CFU/g) on Day 28 of Cycle 3 was also comparable between groups. Administration time was significantly less for TIP (mean: 5.6 versus 19.7min, p<0.0001). Treatment satisfaction was significantly higher for TIP for effectiveness, convenience, and global satisfaction. CONCLUSIONS TIP has a safety and efficacy profile comparable with TIS, and offers a far more convenient treatment option for pseudomonas lung infection in CF.