S3815 Dasatinib-Induced Inflammatory Reactive Polyposis

Introduction: Inflammatory reactive polyposis due to dasatinib use has only been described twice in literature. This is the third documented case of inflammatory reactive polyposis from dasatinib use in a patient with chronic myelocytic leukemia (CML). Case Description/Methods: A 57-year-old White woman with past medical history of CML presented with complaints of fatigue, right upper quadrant pain and intermittent diarrhea. Labs revealed iron deficiency anemia. Medications included dasatinib (Sprycel), a tyrosine kinase inhibitor used as a targeted cancer drug to treat certain types of leukemia, particularly CML and Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL). Colonoscopy done to evaluate symptoms showed multiple small, sessile friable polyps with mucous caps extending throughout the length of the colon. A few polyps were sampled for pathology which revealed colonic mucosa with surface erosion/ulceration, underlying granulation tissue, and active inflammation, consistent with inflammatory polyps. Findings, pathology and recommendations were discussed with oncology. Decision was made to decrease the dose of dasatinib. Discussion: Till date, there are only 2 case reports which described dasatinib induced inflammatory reactive polyposis. First case reported significant improvement and resolution of polypsis 4 months after discontinuing dasatinib. The second case report recommended to continue dasatinib at a lower dose of 50 mg/d if intolerant of alternative CML therapies and perform surveillance colonoscopies at regular intervals. Dasatinib being a tyrosine kinase inhibitor results in suppression of regulatory T-cell function which may promote inflammatory reactive polyposis. Further studies are needed to understand natural history and pathophysiological effects of prolonged polyposis. Studies are also needed to elucidate inflammatory effects of dasatinib.