CFTR and cystic fibrosis: On-going combinatorial studies with VX-770, novel potentiators, VX-561—which is an altered form of VX-770, ABBV-3067, and PTI-808; novel correctors, VX-661, VX-445, VX-659, VX-121, ABBV-2222, and PTI-801; and amplifier, PTI-428, which increases the amount of CFTR produced, suggest that a single drug therapy will not be sufficient for optimal management of CF disease (NCT03912233, NCT03969888, NCT03500263)25–30.