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 (FEV1). RESULTS The change from baseline through week 24 in the percent of predicted FEV1 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 patient’s 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.

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.

Background We examined data from a Phase 2 trial {NCT00457821 } of ivacaftor, a CFTR potentiator, in cystic fibrosis (CF) patients with a G551D mutation to evaluate standardized approaches to sweat chloride measurement and to explore the use of sweat chloride and nasal potential difference (NPD) to estimate CFTR activity. Methods Sweat chloride and NPD were secondary endpoints in this placebo-controlled, multicenter trial. Standardization of sweat collection, processing, and analysis was employed for the first time.. Sweat chloride and chloride ion transport (NPD) were integrated into a model of CFTR activity. Results Within-patient sweat chloride determinations showed sufficient precision to detect differences between dose-groups and assess ivacaftor treatment effects. Analysis of changes in sweat chloride and NPD demonstrated that patients treated with ivacaftor achieved CFTR activity equivalent to approximately 35%–40% of normal. Conclusions Sweat chloride is useful in multicenter trials as a biomarker of CFTR activity and to test the effect of CFTR potentiators.

Background:Confirmed Expanded Disability Status Scale (EDSS) progression occurring after a fixed-study entry baseline is a common measure of disability increase in relapsing-remitting multiple sclerosis (RRMS) studies but may not detect all disability progression events, especially those unrelated to overt relapses.Objective:To evaluate possible measures of disability progression unrelated to relapse using EDSS data over ≈5.5 years from the Tysabri® Observational Program (TOP).Methods:TOP is an ongoing, prospective, open-label study in RRMS patients receiving intravenous 300 mg natalizumab every 4 weeks. Measures of increasing disability were assessed using as a reference either study baseline score or a “roving” system that resets the reference score after ⩾24- or ⩾48-week confirmation of a new score.Results:This analysis included 5562 patients. Approximately 70% more EDSS progression events unrelated to relapse and 50% more EDSS worsening events overall were detected with a roving reference score (cumulative probability: 17.6% and 29.7%, respectively) than with a fixed reference baseline score (cumulative probability: 10.1% and 20.3%, respectively).Conclusion:In this long-term observational RRMS dataset, a roving EDSS reference value was more efficient than a study baseline EDSS reference in detecting progression/worsening events unrelated to relapses and thus the transition to secondary progressive disease.

Extended-release naltrexone (XR-NTX) is a once-a-month injectable formulation that is Food and Drug Administration-approved for the treatment of alcohol dependence in patients able to abstain from alcohol before treatment initiation. This paper presents the results of an analysis of efficacy data from a subgroup of patients with 4 days or more of voluntary abstinence before treatment initiation (n = 82) on a wide range of drinking-related outcomes. In these patients, all of whom received counseling, the rate of abstinence was severalfold higher for XR-NTX 380 mg compared with placebo: median time to first drink was 41 days versus 12 days, respectively; rate of continuous abstinence at end of the study was 32% versus 11% (P = 0.02). Extended-release naltrexone 380 mg, compared with placebo, substantially increased time to first heavy drinking event (>180 days vs 20 days; P = 0.04) and decreased the median number of any drinking days per month by 90% (0.7 vs 7.2; P = 0.005) and heavy drinking days per month by 93% (0.2 days vs 2.9 days; P = 0.007). The XR-NTX 380 mg group also had more than twice as many responders compared with placebo (70% vs 30%; P = 0.006; responder defined as having no more than 2 heavy drinking days in any consecutive 28-day period) and experienced greater improvement in gamma-glutamyl transpeptidase levels (P = 0.03). Outcomes for XR-NTX 190 mg (n = 26) were generally intermediate, demonstrating a dose-response effect. In conclusion, XR-NTX 380 mg prolonged abstinence and reduced the number of heavy drinking days and drinking days in patients who were abstinent for as few as 4 days before treatment initiation.