FDA expands cystic fibrosis treatment

FDA expanded the use of ivacaftor (Kalydeco, Vertex Pharmaceuticals) to treat cystic fibrosis.

“Many rare cystic fibrosis mutations have such small patient populations that clinical trial studies are not feasible,” said Janet Woodcock, MD, director of FDA’s Center for Drug Evaluation and Research, in a FDA statement.  “This challenge led us to using an alternative approach based on precision medicine, which made it possible to identify certain gene mutations that are likely to respond to Kalydeco.

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The approval triples the number of rare gene mutations that Kalydeco can now treat, expanding the indication from the treatment of 10 mutations, to 33.

Kalydeco is indicated for patients aged 2 years and older who have one mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that is responsive to drug treatment based on clinical and/or in vitro (laboratory) data. The expanded indication will an addition 3% of the cystic fibrosis population-around 900 patients out of 30,000 total patients in the United States.

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Kalydeco, available as tablets or oral granules taken 2 times a day with fat-containing food, helps the protein made by the CFTR gene function better and as a result, improves lung function and other aspects of cystic fibrosis, including weight gain.

FDA based its decision, in part, on the results of laboratory testing, which it used in conjunction with evidence from earlier human clinical trials. “The approach provides a pathway for adding additional, rare mutations of the disease, based on laboratory data,” FDA said.

Results from an in vitro cell-based model system have been shown to reasonably predict clinical response to Kalydeco. When additional mutations responded to Kalydeco in the laboratory test, researchers were thus able to extrapolate clinical benefit demonstrated in earlier clinical trials of other mutations.

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