Safety of Stopping Pancreatic Enzyme Replacement Therapy in Children With Improved Pancreatic Function After Highly Effective Modulator Therapy

The goal of this clinical trial is to evaluate the safety of stopping pancreatic enzyme replacement therapy (PERT) in children with cystic fibrosis (CF) receiving CFTR modulator therapy (CFTRm) who have regained pancreatic sufficiency. The main questions it aims to answer are: 1. Does discontinuation of PERT affect gastrointestinal symptoms, nutritional status, pancreatic function, or body composition over 6 months? 2. Does stopping PERT increase gastrointestinal symptoms or affect nutritional status, pancreatic function, or body composition compared with continuing PERT? Researchers will evaluate changes in growth, gastrointestinal symptoms, vitamin levels, pancreatic function, and body composition following PERT discontinuation. Participants will: * Complete study visits and assessments over 6 months * Continue or discontinue PERT based on study assignment * Undergo anthropometric measurements * Complete questionnaires about gastrointestinal symptoms * Provide blood samples to assess vitamin levels and coagulation markers * Provide stool samples to measure fecal elastase-1 (FE-1) and evaluate pancreatic function

Inclusion Criteria: * Diagnosis of cystic fibrosis. * History of pancreatic insufficiency, documented by a prior fecal elastase-1 (FE-1) concentration \ 60 days or bowel length less than 25% * Moderate to severe malnutrition, defined as a BMI-for-age z score ≤ -2 for participants aged ≥2 years or a weight-for-length z score ≤ -2 for participants aged \