S3021 Checkpoint Inhibitor-Induced Gastritis

Abstract

INTRODUCTION: Nivolumab, a novel chemotherapy drug, is a monoclonal antibody immune checkpoint inhibitor that is commonly used in the treatment of many different malignancies. Immune checkpoint pathways are important for immune response regulation, and their inhibition has been associated with autoimmune reactions affecting several different organ systems. While multiple GI side effects have been documented, gastritis appears to be rare. As the use of these agents becomes more frequent, so too will their side effects. Clinicians should familiarize themselves with the potential adverse effects of these medications. CASE DESCRIPTION/METHODS: A 61 year old man with a PMH of HTN, Type 2 DM, and Stage III malignant melanoma of the plantar surface of his right foot, now on Nivolumab, presented to clinic with intermittent mid-epigastric abdominal pain, nausea/vomiting, and decreased PO intake. Recent abdominal CT imaging showed diffuse gastric wall thickening. EGD was performed showing severe, diffuse, hemorrhagic gastric inflammation characterized by adherent blood, edema, erythema, friability and shallow ulcerations concerning for drug induced injury vs malignancy. Biopsies were obtained and showed severe chronic active gastritis with extensive ulceration, inflammatory granulation tissue formation, focal complete-type intestinal metaplasia, and bacterial colonies. Nivolumab was discontinued, and the patient was started on pantoprazole, prednisone and sucralfate. His symptoms resolved, and a repeat upper endoscopy showed marked improvement in the gastric mucosa. DISCUSSION: Indications for checkpoint inhibitor use continue to increase, and their side effects will likely become more frequent. Lower GI involvement is well described but gastritis is rare. PD-1 induced autoimmunity should be considered in patients presenting with gastritis and recent use of Immune checkpoint inhibitor therapy. EGD with gastric biopsies is required to confirm the diagnosis. PD-1 inhibitor associated gastritis histopathology findings are non-specific, but common findings include epithelial lymphocyte and neutrophil infiltration, lamina propria expansion and crypt gland abscesses. Treatment consists of discontinuing the offending agent and corticosteroids. If the side effects are mild, clinicians can attempt to restart the medication or use alternative checkpoint inhibitors. Given that the presentations of checkpoint inhibitor gastritis appears to be variable and non-specific, clinicians should have a high suspicion for this complication.Figure 1.: gastric fundus, severe hemorrhagic gastritis.Figure 2.: pre-pyloric stomach, inflammation and ulceration.Figure 3.: gastric body nodularity.