P234 Remission state in Inflammatory Bowel Disease patients on anti TNF or vedolizumab: a confocal endomicroscopy study

Background
Confocal endomicroscopy is a technique allowing the in vivo assessment of the superficial layers of the mucosa, including the epithelium, the surrounding connective tissue and blood vessels. Some of the features observed by endomicroscopy can’t be assessed by classical histology. Preliminary studies have already suggested its added value in the assessment of endoscopic remission in IBD. However, most of these studies were performed on patients still having some endoscopic activity. Furthermore, to our knowledge, no study has used endomicroscopy to compare the state of remission in IBD patients under vedolizumab and anti TNF. Our aim was to disclose persisting endomicroscopy anomalies in patients with full endoscopic healing and to compare them between vedolizumab and anti-TNF.
Methods
We screened patients with CD or UC treated for more than 6 months by adalimumab, infliximab, or vedolizumab, and being in steroid-free clinical (PRO2) and biological remission (CRP<5 mg/l and F Cal <250 microg/g). Confocal endomicroscopy analysis was performed in the ileum, right colon, transverse colon, left colon and rectum. In each ileal segment, we recorded fluorescein leakage, the presence of epithelial erosions, gap junction anomalies and vessel diameter. In each colonic segment, we recorded the presence of fluorescein leakage, crypt dilatation, vessel diameter, and hypervascularization. Patients were prospectively follow-up and clinical relapses (PRO2 + one objective marker) were recorded.
Results
72 CD and UC patients treated by biologic therapy and in clinical remission were screened. 37 of them were also in endoscopic remission (eMayo=0 in UC and absence of ulcer or erosion in CD) and were included in our study. Their treatment were infliximab (n=5), adalimumab (n=16), vedolizumab (n=15) and ustekinumab (n=1). We found a persistence of residual endomicroscopy anomalies in the different segments in a substantial number of patients (table 1). These persisting abnormalities were not significantly associated with any demographic or clinical characteristics including the treatment (anti-TNF or vedolizumab), nor with histologic parameters (almost all patients were in histologic remission), levels of CRP or F Cal.
The average follow-up time was 33.4 (+/- 9.5) months. Among the 37 patients, 7 (18.9%) relapsed. The risk of relapse was not associated with any clinical, biological, histologic or endomicroscopy factor.
Conclusion
Despite endoscopic, biological and even histologic remission, we found a high prevalence of endomicroscopic abnormalities, which were not different between anti-TNF and vedolizumab treated patients. The clinical significance of these anomalies remains to be clarified.