Ataluren: a 'no-nonsense' approach for pulmonary diseases

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

Aminoglycoside antibiotics, such as gentamicin, may induce premature termination codon (PTC) readthrough and elude the nonsense-mediated mRNA decay mechanism. Because PTCs are frequently involved in lysosomal diseases, readthrough compounds may be useful as potential therapeutic agents. The aim of our study was to identify patients responsive to gentamicin treatment in order to be used as positive controls to further screen for other PTC readthrough compounds. With this aim, fibroblasts from 11 patients affected by 6 different lysosomal diseases carrying PTCs were treated with gentamicin. Treatment response was evaluated by measuring enzymatic activity, abnormal metabolite accumulation, mRNA expression, protein localization, and cell viability. The potential effect of readthrough was also analyzed by in silico predictions. Results showed that fibroblasts from 5/11 patients exhibited an up to 3-fold increase of enzymatic activity after gentamicin treatment. Accordingly, cell lines tested showed enhanced well-localized protein and/or increased mRNA expression levels and/or reduced metabolite accumulation. Interestingly, these cell lines also showed increased enzymatic activity after PTC124 treatment, which is a PTC readthrough-promoting compound. In conclusion, our results provide a proof-of-concept that PTCs can be effectively suppressed by readthrough drugs, with different efficiencies depending on the genetic context. The screening of new compounds with readthrough activity is a strategy that can be used to develop efficient therapies for diseases caused by PTC mutations.

Ivacaftor: a novel mutation modulating drug

Cystic fibrosis (CF) is multisystemic disorder presenting in newborn period to adulthood, predominantly affecting respiratory system. It is caused by mutation in CF transmembrane conductance regulator gene. ΔF508 is the most common mutation seen worldwide. Supportive management with bronchodilators, anti-inflammatory, mucolytics, antibiotics are the corner stone of therapy. Mutation specific drug, Ivacaftor, was recently approved USFDA in January 2012 for patients carrying G551D mutation. It is approved in patients who are six years and older in 150 mg twice daily dosing schedule with fat containing meals. It improves the lung function and other aspects of disease including weight gain. The side effects like upper respiratory infection, headache, rash, diarrhoea, stomach ache and dizziness are mild and self-limiting. This is excellent example of promise of personalised medicine - targeted drug that treat patients with specific genetic makeup.