P3404 - Pembrolizumab-Induced Hemorrhagic Gastritis With Superimposed CMV Gastritis Complicated by Treatment Failure

Srikara Gondhi, MBBS, Gregory Pajot, MD
Advocate Illinois Masonic Medical Center, Chicago, IL

Introduction: Pembrolizumab, an Immune checkpoint inhibitor, is an anti-programmed cell death-1 (PD-1) humanized monoclonal antibody (MAO) that inhibits (PD-1) activity. Immune checkpoint inhibitors (ICIs) are immunomodulatory antibodies and function by enhancing the immune system. Unlike colitis, hemorrhagic gastritis is not a well-documented gastrointestinal (GI) immune-related adverse event (irAE).

Case Description/Methods: Here, we present a rare case of hemorrhagic gastritis secondary to adjuvant immunotherapy with pembrolizumab in a 39-year-old female patient with stage IIIb right-sided triple-negative breast carcinoma, germline BRCA wild-type treated with chemotherapy and right mastectomy. The patient could not complete the pembrolizumab treatment due to abdominal pain, nausea, and heartburn. Esophagogastroduodenoscopy (EGD) revealed acute ulcerative hemorrhagic gastritis. After starting treatment with prednisone and proton pump inhibitor (PPI), a biopsy revealed superimposed cytomegalovirus (CMV) infection. Treatment failure with valganciclovir resulted in switching to foscarnet and finally switching again to valganciclovir and prednisone. Repeat EGD a month and six months later showed gradual resolution of the gastritis.

Discussion: This patient required multiple hospitalizations due to both treatment failure and socioeconomic issues. We present this rare case in hopes that the similarities between both presentations and the possibility of treatment failure will be in the broad differential in patients presenting with GI-related adverse effects post-treatment with pembrolizumab.



Disclosures:


Srikara Gondhi, MBBS, Gregory Pajot, MD. P3404 - Pembrolizumab-Induced Hemorrhagic Gastritis With Superimposed CMV Gastritis Complicated by Treatment Failure, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.