This study is a Phase 2, double-blind, randomized, placebo-controlled study to evaluate the safety and efficacy of CTX-4430 administered once-daily for 48 weeks for treatment of CF. A total of 195 pulmonary CF patients that meet all the inclusion and no exclusion criteria and provide written informed consent will be randomized to receive 50 mg CTX-4430, 100 mg CTX-4430, or placebo in a 1:1:1 ratio. Follow-up visits will be conducted approximately every 4 weeks from Week 4 to Week 52 (4 weeks after completion of treatment).
