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P194. Methylene Blue orally administered tablets (MB MMX®) is effective in detecting intraepithelial dysplasia in patients with long standing ulcerative colitis

S. Danese1, G. Fiorino1, A. Repici2, 1IRCSS Humanitas, IBD Center, Rozzano, Italy, 2IRCCS Humanitas, Gastroenterology and Digestive Endoscopy, Rozzano, Italy

Background

Patients with UC have an increased risk of colonic dysplasia and colon cancer. Chromoendoscopy (CE) with methylene blue (MB) can increase dysplasia detection. A formulation of MB 25 mg orally administered tablets (MB MMX®) allows colonic mucosal staining and could facilitate CE. The PK characteristics of the tablets were: mean Cmax 1149.12 ng/mL, Tmax 16.0 hrs, and T1/2 15.08 h. 38.7% of the dose was escrited in the urine. After administration of MB MMX tablets, the drug presence in the blood was assured for at least 30 h.

Methods

Long standing UC patients (equal or more than 8 years) in clinical remission requiring surveillance colonoscopy were enrolled. Patients underwent a standard 4 L PEG based bowel preparation and took in addition 8 tablets of 25 mg MB MMX®, according to a defined schedule. The endoscopic activity index was assessed by Rachmilevitz score (from 0 to 12). The quality of the staining was assessed using a specific scoring scale ranging from 0 (no staining) to 5 (over-stained). Colon was divided into 4 target regions: ascending colon (AC), transverse (TC), descending (DC) and rectosigmoid (RES). Each colonic region and for the whole colon was scored for staining. Targeted biopsies from areas suspected for dysplasia, and random biopsies as per standard screening procedures were collected.

Results

59 patients (F 24/ M 35, mean age 46 y) were screened, 52 were enrolled and included in the analysis. Mean disease duration was 19 y (range 8–52 y). Mean CAI was 1.3 (range: 0–7) and mean Rachmilewitz Endoscopic score was 2.1 (range: 0–9). Mean colon cleaning score (Boston classification) was 4.8. Mean number of biopsy was 39 (range 16–65), mean time of endoscopy was 47 minutes (range: 20–110 minutes).

The mucosal staining efficacy of Methylene Blue MMX® tablets was on average acceptable (50% of the mucosa stained in all 4 examined colonic regions). The majority of subjects (63.4%) had a number of stained areas with a staining score >2 of 4 regions. Histopathological analysis confirmed IN in 4 subjects with endoscopic suspected areas. IN were found in 3/44 subjects with no endoscopic suspicion of dysplasia (2 in the RES, 1 in the AC). Accuracy was 86% (CI 95%, 74%-94%).

Conclusion

MB MMX® appears to be accurate in detecting or excluding IN in UC patients. Improvements in colonic staining, in bowel cleaning, and endoscopist's training might increase the sensitivity of this procedure. Phase III trial comparing this technique with standard light endoscopy is planned.