Additional Relevant Details
The sNDA is based on preclinical data for ivacaftor in residual function mutations, the established clinical profile of KALYDECO and on previously reported data from an exploratory Phase 2a study. In 19 of the 24 patients enrolled in this study, eight of the 23 mutations proposed in the sNDA were represented.CF is caused by defective or missing cystic fibrosis transmembrane conductance regulator (CFTR) proteins resulting from mutations in the CFTR gene. The defective or missing proteins result in poor flow of salt (chloride) and water into and out of the cell in a number of organs, including the lungs. Chloride transport is a marker of the function of the CFTR protein at the cell surface. KALYDECO, which received the FDA's Breakthrough Therapy Designation in 2013, is currently approved in the U.S. to treat people with CF ages 2 and older who have one of 10 mutations in the CFTR gene (G551D, G1244E, G1349D, G178R,G551S, S1251N, S1255P, S549N, S549R or R117H). As with the mutations for which KALYDECO is approved, this group of 23 residual function mutations is known to have some functional CFTR protein at the cell surface. This submission was also based on observed in vitro increases in chloride transport in response to ivacaftor in cells expressing CFTR. The presence of CFTR protein at the cell surface and increases in chloride transport are characteristics associated with clinical response to KALYDECO.