Abstract
Acute gastrointestinal (GI) immune-related adverse events (irAE) are commonly reported by patients with cancer undergoing treatment with immune checkpoint inhibitors (CPI); however chronic irAEs are rare. We present a case of a 71-year-old woman with metastatic gastro-oesophageal junction (GOJ) adenocarcinoma who developed delayed-onset chronic intestinal pseudo-obstruction (CIPO) while receiving second-line pembrolizumab. Repeated CT scans of the abdomen/pelvis found no small bowel obstruction, and evaluations for bowel inflammation, infection and paraneoplastic syndrome were negative. Bowel rest and glucocorticoids were associated with transient symptom resolution; however, symptoms recurred within 1 month. The patient was ultimately supported with total parenteral nutrition and intestinal motility agents. After 4 months, the GOJ cancer remained stable with no signs of progression. As CPI use expands, the incidence of rare irAEs, such as CIPO, may increase.