OPTION: A Trial to Assess the Safety & Efficacy of MS1819 in Patients With Exocrine Pancreatic Insufficiency Due to Cystic Fibrosis

Inclusion Criteria: 1. Cystic fibrosis, based on 2 clinical features consistent with CF, plus initial diagnostic sweat chloride ≥ 60 mmol/L 2. Under stable dose of porcine PERT 3. A fair or better nutritional status 4. Fecal elastase \<100 µg/g 5. Standard-of-care medications including Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulators are allowed Exclusion Criteria: 1. History or diagnosis of fibrosing colonopathy 2. Any chronic diarrheal illness unrelated to pancreatic insufficiency 3. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) level ≥5 ×upper limit of normal (ULN), or total bilirubin level ≥1.5 ×ULN at the Screening visit 4. Feeding via an enteral tube during 6 months before screening 5. Forced expiratory volume ≤30% at the Screening visit