Novel approach allows expansion of indication for cystic fibrosis drug

Typically, when the US Food and Drug Administration approves an expansion of the indication for a drug, it means that additional clinical data have shown the drug can safely and effectively treat patient populations other than those for which it was originally intended.

But collecting additional clinical data is sometimes very difficult, especially with rare diseases. Patient populations are small and are often scattered throughout the country or the world, and therefore hard to access, noted a posting by the FDA’s Division of Drug Information in relation to this week’s extension of indications for Vertex Pharmaceuticals’ (Nasdaq: VRTX) cystic fibrosis (CF) drug Kalydeco (ivacaftor).

In the case of the drug Kalydeco - a drug that works in patients with specific mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene that cause cystic fibrosis (CF) - expansion of the indication was possible, thereby offering a disease-modifying treatment option to hundreds of patients living with CF, despite not having additional clinical data. To approve the indication expansion, a novel approach was used that relied on evidence from laboratory-based in vitro assay data. These data gave the agency sufficient information to determine whether certain populations with CF would likely respond to the drug.