MUSC Health Cystic Fibrosis Center, Medical University of South Carolina, Charleston, SC, USA. Electronic address: flumepa@musc.edu. Quartier Bleu, Lindenhof Hospital, Bern, Switzerland. Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK. Department of Pulmonary and Critical Care Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. Pneumologische Praxis München-Pasing, Munich, Germany. Pediatric Pulmonology, University Hospital of Leuven, Leuven, Belgium. Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA. Vertex Pharmaceuticals Incorporated, Boston, MA, USA. ICON Clinical Research Inc, North Wales, PA, USA. Vertex Pharmaceuticals Incorporated, Boston, MA, USA; US Food and Drug Administration, Silver Spring, MD, USA. Child Health Research Centre, University of Queensland, Brisbane, QLD, Australia.