The U.S. FDA expanded the approved use of Kalydeco (ivacaftor) for treating cystic fibrosis. The approval triples the number of rare gene mutations that the drug can now treat, expanding the indication from the treatment of 10 mutations to 33. The agency said it 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.
“Many rare cystic fibrosis mutations have such small patient populations that clinical trial studies are not feasible,” said Janet Woodcock, M.D., director of the FDA’s Center for Drug Evaluation and Research. “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.
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. This resulted in the addition of gene mutations for which the drug is now indicated.
Kalydeco is manufactured for Boston-based Vertex Pharmaceuticals Inc.