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Am J Respir Crit Care Med. 2018 Jun 1;197(11):1433-1442. doi: 10.1164/rccm.201710-1983OC.

Effects of Lumacaftor-Ivacaftor Therapy on Cystic Fibrosis Transmembrane Conductance Regulator Function in Phe508del Homozygous Patients with Cystic Fibrosis.

Author information

1
1 Department of Translational Pulmonology.
2
2 Division of Pediatric Pulmonology and Allergy and Cystic Fibrosis Center, Department of Pediatrics, and.
3
3 Translational Lung Research Center Heidelberg, German Center for Lung Research, University of Heidelberg, Heidelberg, Germany.
4
4 Department of Pediatric Pulmonology and Immunology and Cystic Fibrosis Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.
5
5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.
6
6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany.
7
7 Department of Pediatrics, Justus-Liebig-University Giessen, Giessen, Germany.
8
8 Universities of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany.
9
9 Department of Pneumology and Respiratory Critical Care Medicine, Thoraxklinik, University Hospital Heidelberg, Heidelberg, Germany; and.
10
10 Medical Clinic VII, Sports Medicine, Heidelberg University Hospital, Heidelberg, Germany.

Abstract

RATIONALE:

The combination of the CFTR (cystic fibrosis transmembrane conductance regulator) corrector lumacaftor with the potentiator ivacaftor has been approved for the treatment of patients with cystic fibrosis homozygous for the Phe508del CFTR mutation. The phase 3 trials examined clinical outcomes but did not evaluate CFTR function in patients.

OBJECTIVES:

To examine the effect of lumacaftor-ivacaftor on biomarkers of CFTR function in Phe508del homozygous patients with cystic fibrosis aged 12 years and older.

METHODS:

This prospective observational study assessed clinical outcomes including FEV1% predicted and body mass index, and CFTR biomarkers including sweat chloride concentration, nasal potential difference, and intestinal current measurement before and 8-16 weeks after initiation of lumacaftor-ivacaftor.

MEASUREMENTS AND MAIN RESULTS:

A total of 53 patients were enrolled in the study, and 52 patients had baseline and follow-up measurements. After initiation of lumacaftor-ivacaftor sweat chloride concentrations were reduced by 17.8 mmol/L (interquartile range [IQR], -25.9 to -6.1; P < 0.001), nasal potential difference showed partial rescue of CFTR function in nasal epithelia to a level of 10.2% (IQR, 0.0-26.1; P < 0.011), and intestinal current measurement showed functional improvement in rectal epithelia to a level of 17.7% of normal (IQR, 10.8-29.0; P < 0.001). All patients improved in at least one CFTR biomarker, but no correlations were found between CFTR biomarker responses and clinical outcomes.

CONCLUSIONS:

Lumacaftor-ivacaftor results in partial rescue of Phe508del CFTR function to levels comparable to the lower range of CFTR activity found in patients with residual function mutations. Functional improvement was detected even in the absence of short-term improvement of FEV1% predicted and body mass index. Clinical trial registered with www.clinicaltrials.gov (NCT02807415).

KEYWORDS:

cystic fibrosis; cystic fibrosis transmembrane conductance regulator biomarker; intestinal current measurement; nasal potential difference; sweat test

PMID:
29327948
DOI:
10.1164/rccm.201710-1983OC
[Indexed for MEDLINE]

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