Target number of inclusion not reached

The main objective of the study is to evaluate the effectiveness of polyethylene glycol treatment on intestinal inflammation in children with cystic fibrosis. In this test, a method adapted from the Fleming one-step scheme will be used. The success rate is measured by the proportion of patients with fecal calprotectin levels < 250 µg/g at 3 months after treatment initiation.

Cystic fibrosis is one of the most frequent serious genetic diseases in France (7000 patients). It is the consequence of mutations in the CFTR gene, encoding a protein involved in the hydro-electrolytic balance of secretions. Beyond the well-known lung damage in these patients, intestinal inflammation is present in the majority of patients.

While advances in the management of cystic fibrosis are increasing patient life expectancy, other issues are emerging, including the impact of this chronic intestinal inflammation on the nutritional status and high risk of digestive cancers.

Currently, no management is proposed to treat this intestinal inflammation. The use of laxatives to fluidize digestive secretions and restore a digestive ecosystem close to the healthy subject could constitute a new therapeutic approach to this intestinal inflammation, as previously shown in the mouse model of cystic fibrosis. However, to date, to the investigator's knowledge, no studies have evaluated the effect of laxative treatment on intestinal inflammation of cystic fibrosis in humans.

This study is a bi-centric, non-comparative, prospective study for a phase II trial according to a Fleming scheme.

Study participants will take a 3-month laxative treatment with polyethylene glycol for 3 months. In addition to the inclusion visit, a follow-up visit will take place at 3 months and 3 intermediate telephone calls will be made to ensure efficacy, tolerance and compliance.

Inclusion Criteria:

• Age ≥ 4 years old and <18 years old ;
• Patient with cystic fibrosis (sweat test > 60 mmol/l and/or molecular biology identifying mutations in the CFTR gene) with associated pancreatic insufficiency (fecal elastase <100 µg/g);
• With a rapid calprotectin assay result via the IBDoc test (Bühlmann®) superior or equal to 250 µg/g;
• Person affiliated or benefiting from a social security scheme;
• Free, informed and written consent signed by the holders of parental authority and the investigator before any examination required by the research and oral and/or written consent by the participant (depending on his/her age).

Exclusion Criteria:

• Ongoing processing that can modulate the functionality of the CFTR (such as lumacaftor-ivacaftor protein therapy);
• Patient already on polyethylene glycol or other laxative within 3 months before the inclusion visit;
• Patient with diarrhea at inclusion (diarrhea will be defined as the presence of 3 or more stools / day in the 7 days prior to the inclusion visit);
• Acute viral or bacterial diarrhea in the month prior to the inclusion visit (associated with fever);
• Cure of oral or intravenous antibiotics or antifungals in the month preceding the collection of samples;
• Change in background treatment in the month prior to the inclusion visit (oral or inhaled corticosteroid therapy, azithromycin, inhaled antibiotic therapy, inhaled antifungal agent, proton pump inhibitors);
• Taking probiotics in the month before the inclusion visit;
• Transplanted patient (on immunosuppressants);
• Patient with IBD or celiac disease;
• Patient with digestive perforation or risk of digestive perforation;
• Patient with ileus or suspicion of intestinal obstruction, symptomatic stenosis;
• History of hypersensitivity to macrogol or any of the excipients
• Holders of parental authority enjoying judicial protection.