In-Depth Assessment of Endoscopic Remission in Inflammatory Bowel Disease Treated by Anti-TNF or Vedolizumab

Background and aims: Confocal endomicroscopy is a technique allowing the in vivo assessment of the superficial layers of the mucosa. Preliminary studies have already suggested its added value in the assessment of endoscopic remission in inflammatory bowel disease. However, most of these studies were performed on patients still having incomplete mucosal healing. Our aim was to disclose persisting endomicroscopic anomalies in patients with full endoscopic remission and to compare them between vedolizumab- and anti-tumor necrosis factor-treated patients. Methods: We screened patients with Crohn's disease (CD) or ulcerative colitis (UC) treated for more than 6 months with biologic therapy, and being in steroid-free clinical and biological remission. White light endoscopy and probe-based confocal laser endomicroscopy (pCLE) analysis were performed in the ileum, right colon, transverse colon, left colon, and rectum. Full endoscopic remission was defined by a Mayo endoscopic score of 0 in UC and no remaining ulcer or erosion in CD. Patients were prospectively followed up and clinical relapses were recorded. Results: Seventy-two CD and UC patients treated by biologic therapy and in clinical and biological remission were screened. A total of 37 were also in full endoscopic remission and were included in our study; 183 intestinal segments were analyzed. We found residual pCLE anomalies in most of the patients. These anomalies were not significantly associated with any demographic or clinical characteristic including the treatment received, nor were they associated with histological parameters, levels of C-reactive protein or fecal calprotectin. Among the 37 patients, 7 (18.9%) relapsed over a median follow-up of 33.7 months. The risk of relapse was not associated with any clinical, biological, histologic, or pCLE feature at baseline. Conclusion: Despite endoscopic, biological, and even histological remission, we found a high prevalence of endomicroscopic abnormalities, which were not different between anti-tumor necrosis factor- and vedolizumab-treated patients. The clinical significance of these anomalies remains to be clarified.