Acute colonic pseudo-obstruction following nivolumab and ipilimumab combination therapy for metastatic melanoma

Immune-related adverse events (irAEs) are commonly observed in patients treated with immune checkpoint inhibitors (ICI), and prompt diagnosis and treatment of irAEs is of utmost importance. Gastrointestinal (GI) events are among the most frequent irAEs and the hallmark symptom is diarrhea. Intestinal hypomotility as irAEs is exceedingly rare, and needs wider recognition given that the presentation is insidious. Here, we report a case of 79-year-old woman with metastatic melanoma under nivolumab and ipilimumab combination therapy. She developed ileus symptom, and was diagnosed with acute colonic pseudo-obstruction. The symptom relieved soon after administering high-dose prednisolone five days after the onset. ICI therapy was discontinued. Intestinal hypomotility as GI irAEs is exceedingly rare and there have been five reported cases to our knowledge. In reviewing past cases, we speculate that the prompt initiation of corticosteroids resulted in a favorable outcome. Our case illustrates that early recognition of these rare irAEs is essential in order to ensure prompt treatment.