CFTR and cystic fibrosis: The corrector/potentiator combinations Orkambi (VX-770 plus lumacaftor/VX-809) and Symdeko (VX-770 plus tezacaftor/VX-661) have been approved for CF subjects that are homozygous for the most common CF-causing CFTR mutation, F508del, or who have one F508del allele and a residual function CFTR mutation2.