CFTR and cystic fibrosis: Results from randomized, placebo-controlled clinical trials support the efficacy of CFTR modulator therapies in the treatment of people with CF: IVA in patients with at least one G551D or R117H mutation, non-G551D gating mutation, or residual function mutation [14,15,16,17,18]; LUM/IVA in patients who are F508del homozygous [19,20]; TEZ/IVA in patients who are F508del homozygous or heterozygous with a residual function mutation [18,21]; and ELX/TEZ/IVA in patients who are F508del homozygous or heterozygous with a minimal function mutation [22,23].