Inspire Pharmaceuticals’ Denufosol for cystic fibrosis
Posted by lifetech on August 26th, 2010There is ongoing discussion as to how the cystic fibrosis mutation causes lung disease. The “low airway volume” is a widely accepted hypothesis. It proposes that depletion of “airway surface liquid” impairs ciliary beat and causes the retention of thickened mucus, which predisposes to lung infections. Thus there is considerable interest in developing therapeutic interventions that restore airway surface volume. That is what Inspire is trying to accomplish with denufosol, an agent that may restore airway hydration by activating an alternative ion channel (the P2Y2 receptor). The first denufosol phase III trial (TIGER-1) was technically positive, as it met the study’s primary endpoint. However, clinical results as a whole were not that impressive over 24 weeks, and pulmonary exacerbation results were of particular concern. Favorably, the trial’s open label extension suggests that denufosol may work slowly and steadily – but this observation needs confirmation in a controlled trial. This may be achieved with the second ongoing phase III trial (TIGER-2), which treats a larger number of patients for a longer period of time. Besides considerations of denufosol’s clinical worthiness, TIGER-2 needs to do better than TIGER-1 to avoid regulatory and commercial challenges from other approved and late-stage development airway hydrating agents as well as agents from other classes such as CFTR repair therapies (discussed in our Vertex report). The latter target the basic defect that causes CF, and could dramatically change the CF treatment paradigm in the medium future. Thus, a lot is at stake for TIGER-2. We refer you to our denufosol report for an in-depth discussion of clinical, regulatory and commercial challenges.


