Background: Lumacaftor/Ivacaftor (LUM-IVA), a cystic fibrosis transmembrane conductance regulator (CFTR) protein corrector-potentiator combination, improves lung function and reduces pulmonary exacerbations (PEx) in F508del homozygous CF patients. However, the systemic effects of LUM-IVA outside the respiratory system have not yet been thoroughly investigated. Methods: A prospective, real-world, yearlong study was performed on F508del homozygous adult CF patients who commenced treatment with LUM-IVA. Pancreatic function, bone metabolism, fertility status, nutritional and pulmonary factors were evaluated. Results: Twelve patients, mean age 28.3 years (18.6–43.9) were recruited. Following 12 months of treatment, no changes were detected in glucose, insulin, c-peptide or BMI values. A significant relative decrease in mean alkaline-phosphatase levels (122.8 U/L vs 89.4, p = 0.002) and a trend toward an increase in calcium levels (9.5 vs 9.9 mg/dL, p = 0.074) were observed. A non-significant improvement in mean DEXA spine t-score after a year of treatment (-2.1 vs -1.6, n = 4, p = 0.11) was detected. Sweat chloride concentrations decreased significantly (-21.4 mEq/L; p = 0.003). Pulmonary outcome revealed improvement in spirometry values during the first three months (FEV₁ by 5.7% p = 0.009, FEF_25-75 by 4.3% p = 0.001) with no change in chest CT Bhalla score and CFQR after one year. There was also a significant decrease in parenteral antibiotic events (17 vs 8, p = 0.039) with shift from IV to oral antibiotics for PEx treatment. Conclusions: After one year of treatment, stabilization was observed in the pancreatic indices, nutritional status, structure and function of the lungs, with a beneficial effect on bone mineral metabolism and CFTR function. Additional studies should investigate the effect of CFTR modulators on extra-pulmonary manifestations.

Cystic Fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR), a chloride/bicarbonate channel. Many studies utilize human airway cell models (cell lines and primary cells) to study different aspects of CFTR biology. Media selection can alter the growth and differentiation of primary cells, yet the impact on stable airway cell lines is unclear. To determine the impact of media and growth conditions on CFBE41o- cells stably transduced with wild-type or F508del CFTR, we examined four commonly used growth media, measuring epithelial and mesenchymal markers, as well as CFTR expression, maturation, and function. The selection of growth media altered the expression of epithelial and mesenchymal markers in the cell lines, and significantly impacted CFTR expression and subsequent function. These results highlight the importance of media selection to CFTR and cell line behavior and should be considered in both studies of primary human airway cells and stable cell lines.