A Drug for Cystic Fibrosis!

Good news indeed this week in the New England Journal of Medicine.  Finally, a medication that helps some of the people with cystic fibrosis, and hopefully provides a model of effective intervention for the remainder.

As Rick and I talk about in this week's podcast, cystic fibrosis is the most common lethal genetic disease in Caucasians, affecting about 70,000 people worldwide.  The disease is caused by a defect in transport of salt and water in the lungs, pancreas, sweat glands and gastrointestinal tract, but seems to cause the most trouble, and eventual death, due to manifestations in the lungs.  That's because the mucus secretions normally found in the interior spaces of these organs become really thick.  Most of the coping strategies for cystic fibrosis, or CF, involve attempting to move that glop out of the lungs so people can breath.  Over time, however, bacteria and other bugs, including fungal infections, move in.  Most people with CF die in their thirties or so if they receive very good medical care; they may die much sooner if care is not optimal.

We've known for some time the primary cause of CF- it's the cystic fibrosis transmembrane conductance regulator protein, thank goodness, abbreviated CFTR.  Because of mutations in the genes that regulate this protein, there may not be enough of it in the cell membranes or what is there may not work properly.  The result is aberrant transport of water and salt into and out of the cell, with the result the abnormally thick secretions and mucus.

This study describes ivacaftor, a drug that allows the CFTR to remain open longer than it would ordinarily to allow increased chloride transport activity.  161 subjects were recruited to this phase 3 trial and randomized to either daily ivacaftor or placebo for up to 48 weeks.  Evaluation of lung function as well as a sweat test and other clinical assessments were used to determine efficacy of the drug.  All subjects had to have the precise mutation targeted by this medication, seen in about 4-5% of those with CF.  Good news for these folks then that the drug appeared to be safe and well-tolerated, and improved lung function.

The hope, of course, is that gains from this study and medication will help others with CF who have different gene defects.  It's worth noting, of course, that this drug is just one more of the many targeted therapies being developed in all kinds of diseases and conditions, and the more of those, the better.  Such therapies allow those who will benefit to be treated while avoiding more medication use is those who won't, and that's a win-win.

Other topics this week include low-level alcohol consumption and breast cancer risk in women, safety of handheld scanners in those with implanted heart assist devices in Annal of Internal Medicine, and safety of ADHD medications with respect to heart problems, also in NEJM .  Until next week, y'all live well.

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