S4894 Vedolizumab for Ulcerative Colitis After Treatment of Isolated Rectal Diffuse Large B-Cell Lymphoma

Introduction: Primary gastrointestinal (GI) lymphomas account for <0.2% of all colorectal cancer, the 2 most common being mucosa-associated lymphoid tissue and diffuse large B-cell lymphoma (DLBCL). Immunomodulator therapy is a known risk factor for developing GI lymphoma. There is limited data regarding the safety and efficacy of biologic therapy for IBD management after GI lymphoma, and most recommendations are extrapolated from broader studies of IBD patients, not specific to lymphoma. We present a rare case of a patient with Ulcerative Colitis (UC) presenting with refractory symptoms, found to have primary rectal DLBCL. Case Description/Methods: This is a 50-year-old man with UC who presented to his gastroenterologist with ongoing bloody diarrhea despite an escalating regimen including adalimumab, azathioprine, and prednisone. Diagnostic colonoscopy revealed erythematous, ulcerated, nodular, and plaque-covered rectal mucosa; biopsies confirmed DLBCL. Metastatic evaluation including bone marrow examination, FISH panel, positron emission tomography-computed tomography scan, and upper endoscopy with biopsies was unremarkable; thus, his cancer was deemed an isolated primary rectal DLBCL. He was treated with R-CHOP (combination chemotherapy including rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) which led to remission of both his DLBCL and UC. One year later, he developed recurrence of UC symptoms. He was started on vedolizumab with eventual clinical and endoscopic remission, persistent on histology 5 years later. Discussion: Patients with IBD are known to have higher risk for colorectal cancer, but data evaluating IBD as an independent risk factor for the development of lymphoproliferative disorders are unclear. Multiple reports suggest immunomodulator therapy may increase a patient’s risk for developing lymphoproliferative disorders with thiopurines and tumor necrosis factor inhibitors thought to pose the greatest risk. In its clinical practice update, the American Gastroenterological Association recommends discontinuation of thiopurines after lymphoma treatment, but biologic therapy may still be considered. Registry data suggest biologics have been used after GI lymphoma without evidence of heightened relapse risk. This case exemplifies the rare possibility of primary rectal DLBCL in an IBD patient on immunomodulator therapy and the importance of endoscopy to evaluate persistent symptoms despite standard therapy. Furthermore, this case supports other literature suggesting the safety of biologic therapy following successful GI lymphoma treatment.