This trial will consist of two parts: Part 1 and Part 2. Part 1 will enroll adult healthy volunteers (HV) into four treatment groups. The first group will enroll HV into a single ascending dose (SAD) treatment group consisting of three cohorts. The second group will enroll HV into a multiple ascending dose (MAD) treatment group consisting of three cohorts. The third group will enroll HV into a food effect (FE) treatment group consisting of one cohort. The fourth group will enroll HV into a drug-drug interactions (DDI) treatment group consisting of one cohort. Part 2 will enroll adult subjects with cystic fibrosis (CF) currently on stable ivacaftor/lumacaftor background therapy for a minimum of three months into a MAD treatment group consisting of three cohorts. Approximately 120 subjects will be enrolled.