Proof-of-concept Study to Evaluate the Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of SION-719 When Added to Trikafta

Who May Qualify: - Diagnosis of CF with F508del homozygous genotype based on documented CFTR genotype laboratory report. - Adherent to physician-prescribed Trikafta, as assessed by the Investigator, for at least 3 months prior to the Screening visit, taken at the recommended dose without modifications and on the regimen described in the current prescribing information. - Stable CF disease without pulmonary exacerbation within 28 days before Baseline or acute non-CF-related illness within 14 days before Baseline. Who Should NOT Join This Trial: - Participant has clinically significant current or recurrent illness, other than CF - Participant has a history of malignancy, except for basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of recurrence for at least 1 year. Always talk to your doctor about whether this trial is right for you.