A Phase 2a, Randomized, Placebo-Controlled, Double Blind Multiple Ascending Dose Study in Patients with Cystic Fibrosis Carrying the 3849 +10 Kb C->T Mutation to Evaluate the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of SPL84
The goal of this clinical trial is to learn if drug SPL84 is safe for adult patients with cystic fibrosis (CF). It will also learn if the drug works to treat works to treat CF with a specific mutation. The purpose of this research study is to: * test the safety and effectiveness of multiple doses of the study drug, SPL84 * test how multiple doses of the drug are processed by the body Researchers will compare drug SPL84 to a placebo (a look-alike substance that contains no drug) to see if drug SPL84 is safe and if it works to treat CF. Participants will: Take drug SPL84 or a placebo by inhalation every week for 9 weeks months Visit the clinic approximately 14 times over 17.5 weeks for checkups and tests
• Diagnosis of CF and two CF causing mutations; 3849+10 Kb C-\>T mutation on one allele in the CF transmembrane conductance regulator (CFTR) gene (homozygote or compound heterozygote). Source documentation from a certified genetic laboratory is required.
• Body mass index (BMI) of ≥ 17 kg/m2.
• FEV1 40-90% predicted at screening.
• Non-smokers or vapers for at least 180 days (6 months) prior to screening, per participant report.