Endoscopy 2018; 50(10): 1027-1032
DOI: 10.1055/a-0630-1004
Innovations and brief communications
© Georg Thieme Verlag KG Stuttgart · New York

Evaluation of genotoxicity related to oral methylene blue chromoendoscopy

Alessandro Repici
1  Humanitas Clinical and Research Center, Digestive Endoscopy Unit, Division of Gastroenterology, Rozzano, Italy
2  Humanitas University, Department of Biomedical Sciences, Rozzano, Italy
,
Camilla Ciscato
1  Humanitas Clinical and Research Center, Digestive Endoscopy Unit, Division of Gastroenterology, Rozzano, Italy
,
Michael Wallace
3  Division of Gastroenterology and Hepatology, Mayo Clinic Jacksonville, Florida, USA
,
Prateek Sharma
4  Division of Gastroenterology and Hepatology, Veterans Affairs Medical Center and University of Kansas School of Medicine, Kansas City, USA
,
Andrea Anderloni
1  Humanitas Clinical and Research Center, Digestive Endoscopy Unit, Division of Gastroenterology, Rozzano, Italy
,
Silvia Carrara
1  Humanitas Clinical and Research Center, Digestive Endoscopy Unit, Division of Gastroenterology, Rozzano, Italy
,
Milena Di Leo
1  Humanitas Clinical and Research Center, Digestive Endoscopy Unit, Division of Gastroenterology, Rozzano, Italy
2  Humanitas University, Department of Biomedical Sciences, Rozzano, Italy
,
Cesare Hassan
5  Division of Gastroenterology, Nuovo Regina Elena Hospital, Rome, Italy
› Author Affiliations
TRIAL REGISTRATION: Single-center, non-randomized, prospective trial NCT02295774 at clinicaltrials.gov
Further Information

Publication History

submitted 27 November 2017

accepted after revision 16 April 2018

Publication Date:
15 June 2018 (eFirst)

Abstract

Background An oral formulation of methylene blue with colonic delivery (MB-MMX) has been developed to increase detection of colorectal polys during colonoscopy. Traditionally, there have been safety concerns regarding DNA damage when methylene blue is exposed to white light. The aim of this study was to evaluate DNA damage in colonic mucosa after MB-MMX chromoendoscopy.

Methods This was an open-label phase II safety study to assess for genotoxicity on colorectal biopsies of patients undergoing two sequential colonoscopies before and after an oral dose of 200 mg MB-MMX added to their bowel prep. Analysis of a biomarker of double-stranded DNA breaks, γH2AX, was performed on biopsy specimens.

Results Ten patients were included in the study. The mean expression of γH2AX ± 95 % confidence intervals of the 50 biopsies before and after MB-MMX administration were 0.58 ± 0.08 and 0.62 ± 0.09, respectively (P = 0.24). None of the analyzed samples showed excess positive γH2AX expression, confirming the absence of DNA damage on biopsies after methylene blue exposure. No deaths or serious adverse events occurred.

Conclusions An oral dose of 200 mg of MB-MMX did not result in any detectable DNA damage.

Appendix e1 – e3, Fig. e1, e4, Table e1