STUDY OF THE ADDED VALUE OF A TRANSMURAL EVALUATION IN PATIENTS WITH CROHN'S DISEASE UNDER BIOTHERAPY WITH CLOSE FECAL CALPROTECTIN FOLLOW-UP

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) that can dramatically affect the quality of life of patients. Due to its transmural nature (involvement of the entire thickness of the intestinal wall), it naturally progresses to intestinal destruction (stenosis, fistula) which requires intestinal resection in approximately half of patients during their follow-up. The long-term goal for patients is to maintain a normal life, that is, without symptoms and without intestinal destruction. For this, the short and medium term therapeutic objectives have evolved in recent years. Clinical remission is not a sufficient goal since it has failed to alter the natural history of the disease. The current objective to be achieved is the combination of clinical remission and endoscopic mucosal healing since it is associated with a reduced risk of progression (reappearance of symptoms, hospitalization, intestinal resection). Fecal calprotectin, better accepted than colonoscopy, is a non-invasive biomarker of endoscopic inflammatory activity in CD. The CALM study recently showed that close follow-up with clinical and biological evaluation (assays of CRP and fecal calprotectin), called "tight control", associated with therapeutic intensification in the absence of clinical or biological remission, was associated with a better rate of endoscopic mucosal healing at 1 year than follow-up based solely on symptoms. Thus, the "CALM" strategy is considered to be the current benchmark.

Transmural healing evaluated by MRI is also a promising objective associated with a reduced risk of progression (reappearance of symptoms, hospitalization, bowel resection). In addition, it could prevent intestinal destruction. A recent study by our team suggested that calprotectin (mucosal assessment) and MRI (transmural assessment) may be complementary and be a better therapeutic goal. We hypothesize that a "CALM + MRI" strategy concomitantly targeting transmural healing would be superior to the "CALM" strategy alone in maintaining clinical remission without corticosteroids in patients with CD treated with biotherapies.