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VX770 - Kalydeco

Question
The child in question has G551 and F508 Delta mutations.
For us VX770 provides great hope and just pray soon such a drug will be available to all other CF patients. I have read as much as possible on this drug but do not see information that I would wish to know.

As a person with one faulty gene does not have CF then if VX770 considerably helps the G551 does this mean the quality of life will be so vastly improved that it makes the second gene, in this case F508 Delta irrelevant? Also does VX770 only improve lung function or also help pacreas insufficiency? If the drug works as well as expected would you presume daily 'physio would lessen? I look forward to your answer as I submitted a similar question awhile back but did not receive a reply so unsure if it actually reached. Thank you.
Answer
Thank you for your excellent question. The drug developed for the G551D mutation is called ivacaftor and it was previously called VX770. Full details are now available in a paper recently published in the New England Journal of Medicine. You are correct that the drug ivacaftor has now gone forward for approval. Ivacaftor has indeed shown benefit to patients with the G551D mutation, in outcome measures such as lung function and weight gain, however long-term effects of the drug are still to be established.

You ask in particular about the effect of ivacaftor on patients with the “common gene” (presumably delF508) and G551D. Indeed many patients in the ivacaftor trials have had this combination of mutations and have shown benefit. Ivacaftor has been shown to work only in G551D mutations with another disease causing mutation on the other chromosome. Additionally, there is no clinical benefit shown for people with other mutations and should not be used unless one mutation is G551D.

You also ask about the combination therapy that is currently being investigated (ivacaftor in combination with VX-809). Some results from a Phase II study (short term study assessing safety and efficacy) are now available which show some effect on sweat chloride. Further long term studies are required to ascertain if there is also an effect on symptoms and course of disease. We are optimistic that the further studies on this combination therapy will be undertaken in a timely manner.

NEJM 2011: 365; 18

Best wishes
Lisa Kent, Belfast
Stuart Elborn, Belfast
24.01.2012
The answer is edited by: PhD Lisa Kent