S2972 Pembrolizumab-Induced Gastritis Successfully Treated With Vedolizumab

Abstract

INTRODUCTION: We report a case of histologically-proven gastritis induced by pembrolizumab, a PD-1 inhibitor, successfully treated by vedolizumab. CASE DESCRIPTION/METHODS: A 36-year-old Hispanic female with a history of left breast invasive ductal carcinoma on pembrolizumab presented to oncology clinic with 3 weeks of worsening burning stomach pain. Patient had been receiving pembrolizumab, a PD-1 inhibitor, for 10 months experiencing only grade 1 fatigue, xerostomia, and rash. She also described abdominal bloating that occurred before and after meals. She endorsed a 10 lb weight loss over 1 month but denied fevers, melena, nausea and vomiting. On exam, abdomen was benign and non-tender. Serology labs were unremarkable. After failing empiric PPI therapy, CT scan was ordered showing enlarged peri-gastric lymphadenopathy prompting GI consultation. EGD found diffuse gastritis with friability, erythema and mucosal sloughing. Histology showed chronic active gastritis suggestive of immunotherapy-induced gastritis. She was initially started on prednisone 50mg daily which improved her symptoms minimally; therefore, she received 5 doses of vedolizumab over 6 months resulting in a marked improvement of her upper GI symptoms and increased PO tolerance over the next year. A follow-up EGD and biopsy 8 months later showed normal visualization of the stomach and histology consistent with chronic inactive gastritis. DISCUSSION: Immune-checkpoint inhibitor (ICI) colitis is a well-known adverse event of immunotherapy; however, upper GI manifestations are less commonly reported thus making our patient’s presentation unique. Vedolizumab, an antibody against the α4β7-integrin blocking gut homing lymphocytes, is approved for the treatment of inflammatory bowel diseases and has shown efficacy in treating steroid-refractory ICI colitis.1 Here, we added to growing evidence that vedolizumab may be an effective treatment for steroid-refractory upper GI adverse effects from immunotherapy;2 further studies with larger cohorts of patients are warranted to evaluate safety and efficacy of vedolizumab use in this context.