Case Report of Gastritis as a Complication of Immunotherapy Treatment of Metastatic Endometrial Cancer with Lenvatinib and Pembrolizumab

Immune checkpoint inhibitors (ICIs), such as pembrolizumab (a PD-1 inhibitor), have been shown to be effective in the treatment of a variety of malignancies, including progressive endometrial cancer. ICIs help to activate the patient’s immune system to attack neoplastic cells. However, this immune activation can trigger autoimmune side effects throughout the body, known as immune-related adverse events (irAEs). Immunotherapyassociated hepatitis, colitis and diarrhea have been well documented as irAEs, but gastritis is much less common.1 In this case report of immunotherapy-related gastritis, we attempted to better characterize this more rare condition to assist with early recognition and initiation of appropriate management of immunotherapy-related gastritis. We describe a case of a 73-year-old woman with stage IV uterine carcinosarcoma status post chemoradiation and adjuvant combination immunotherapy using lenvatinib/pembrolizumab. The patient developed moderate-severe gastritis after 13 cycles of lenvatinib/ pembrolizumab with intractable nausea/vomiting. The patient's condition resolved after administration of intravenous (IV) corticosteroids.