Clinical efficacy of fecal occult blood test and colonoscopy for dasatinib-induced hemorrhagic colitis in CML patients

A positive fecal occult blood test (FOBT) is occasionally observed in some chronic myeloid leukemia (CML) patients treated with a tyrosine kinase inhibitor (TKI), and hemorrhagic colitis in patients treated with dasatinib has been reported. To clarify the frequency of TKI-induced hemorrhagic colitis and the screening efficacy of an FOBT followed by a colonoscopy, we prospectively enrolled CML patients treated with a TKI. FOBTs were performed in all patients and colonoscopy was performed in patients with positive FOBTs. When TKI-induced hemorrhagic colitis was pathologically identified, the TKI was interrupted, and the FOBTs were reevaluated. The first FOBT was positive in 10 of 30 patients. All patients with positive FOBTs were treated with dasatinib and developed no symptoms. Dasatinib-induced hemorrhagic colitis was confirmed in 6 of 18 patients treated with dasatinib (33%). Its endoscopic feature was a red flare and/or erosion. Immunohistological analyses showed CD3+, CD8+, CD56+, and Granzyme B+ cytotoxic T lymphocyte infiltration. After dasatinib discontinuation, the FOBTs became negative in all but one patient who had concurrent colorectal polyps. Dasatinib-induced hemorrhagic colitis was observed in one third of asymptomatic patients treated with dasatinib. An FOBT followed by a colonoscopy can be a useful strategy to detect the disease.