Therapeutics development for cystic fibrosis: a successful model for a multisystem genetic disease.
ABSTRACT Cystic fibrosis (CF) is a progressive genetic disease primarily involving the respiratory and gastrointestinal tracts. Multiple therapies directed at CF symptoms and clinical management strategies have emerged from iterative cycles of therapeutics development, helping to change the face of CF from a fatal childhood affliction to a disease in which nearly 50% of U.S. patients are adults. However, as a consequence of therapeutic advances, the burden of CF care is high, and despite progress, most patients succumb to respiratory failure. Addressing the basic defect in CF with systemic small molecules is evolving as a promising approach. A successful collaboration between a voluntary health organization and a pharmaceutical company, complemented by academic investigators and patients, has led to the clinical development of investigational drugs that restore function to defective CFTR protein in various tissues in CF patients. Important activities, leverage points, and challenges in this exemplary collaboration are reviewed with hope that the CF and other genetic disease communities can benefit from the lessons learned in generating new therapeutic approaches in CF.
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ABSTRACT: Mucolipidosis type IV (MLIV) is an autosomal recessive lysosomal storage disorder often characterized by severe neurodevelopmental abnormalities and neuro-retinal degeneration. Mutations in the TRPML1 gene are causative for MLIV. We used lead optimization strategies to identify-and MLIV patient fibroblasts to test-small-molecule activators for their potential to restore TRPML1 mutant channel function. Using the whole-lysosome planar patch-clamp technique, we found that activation of MLIV mutant isoforms by the endogenous ligand PI(3,5)P2 is strongly reduced, while activity can be increased using synthetic ligands. We also found that the F465L mutation renders TRPML1 pH insensitive, while F408Δ impacts synthetic ligand binding. Trafficking defects and accumulation of zinc in lysosomes of MLIV mutant fibroblasts can be rescued by the small molecule treatment. Collectively, our data demonstrate that small molecules can be used to restore channel function and rescue disease associated abnormalities in patient cells expressing specific MLIV point mutations.Nature Communications 08/2014; 5:4681. DOI:10.1038/ncomms5681 · 10.74 Impact Factor
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ABSTRACT: The most prevalent CFTR mutation causing cystic fibrosis, ΔF508, impairs folding of nucleotide binding domain 1 (NBD1) and stability of the interface between NBD1 and the membrane spanning domains (MSDs). The interfacial stability defect can be partially corrected by the investigational drug VX-809 or the R1070W mutation. 'Second-generation' ΔF508-CFTR correctors are needed to improve on the modest efficacy of existing CF correctors. We postulated that a second corrector targeting a distinct folding/interfacial defect might act in synergy with VX-809 or the R1070W suppressor mutation. A biochemical screen for ΔF508-CFTR cell surface expression was developed in a human lung epithelium- derived cell line (CFBE41o-) by expressing chimeric CFTRs with a horseradish peroxidase (HRP) in the fourth exofacial loop either in the presence or absence of R1070W. Using a luminescence read-out of HRP activity, screening of ~110,000 small molecules produced 9 novel corrector scaffolds that increased cell surface ΔF508-CFTR expression by up to 200 % in the presence vs. absence of maximal VX-809. Further screening of 1006 analogs of compounds identified from the primary screen produced 15 correctors with EC50 <5 μM. 8 chemical scaffolds showed synergy with VX-809 in restoring chloride permeability in ΔF508-expressing A549 cells. An aminothiazole increased chloride conductance in human bronchial epithelial cells from a ΔF508 homozygous subject beyond that of maximal VX-809. Mechanistic studies suggested that NBD2 is required for the aminothiazole rescue. Our results provide proof-of-concept for synergy screening to identify second-generation correctors, which, when used in combination, may overcome the 'therapeutic ceiling' of first-generation correctors.Molecular pharmacology 04/2014; DOI:10.1124/mol.114.092478 · 4.12 Impact Factor
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ABSTRACT: Chest physical therapy techniques are essential in order to reduce the frequency of recurrent pulmonary infections that progressively affect lung function in cystic fibrosis patients. Recently, ELTGOL (L'Expiration Lente Totale Glotte Ouverte en décubitus Latéral) emerged as an inexpensive and easy to perform therapeutic option. The aim of this study was to compare the acute effects of ELTGOL and the Flutter valve in stable adult patients with cystic fibrosis. [Subjects and Methods] This was a randomized, crossover study with a sample of cystic fibrosis outpatients. The subjects underwent two protocols (Flutter Valve and ELTGOL interventions, referred to as ELTGOL and FLUTTER) in a randomized order with a one-week washout interval between them. The main outcomes were pulmonary function variables and expectorated sputum dry weight. [Results] ELTGOL cleared 0.34 g more of secretions than FLUTTER (95% CI 0.11 to 0.57). When comparing the physiological effects of ELTGOL and FLUTTER, the first was superior in improving airway resistance (-0.51 cmH2O/L/s; 95% CI -0.88 to -0.14) and airway conductance (0.016 L/s/cmH2O; 95% CI 0.008 to 0.023). [Conclusion] ELTGOL promoted higher secretion removal and improvement in airway resistance and conductance than the Flutter valve. These techniques were equivalent in reducing the pulmonary hyperinflation and air trapping in cystic fibrosis patients.Journal of Physical Therapy Science 06/2014; 26(6):813-6. DOI:10.1589/jpts.26.813 · 0.20 Impact Factor