Severe upper gastrointestinal disorders in pembrolizumab-treated non-small cell lung cancer patient.

Pembrolizumab is an immune checkpoint inhibitor that induces side effects called "immune-related adverse events" (irAEs). Various types of organs are affected by irAEs, although reports of upper gastrointestinal disorders are rare. Here, we report a case of extensive inflammatory pathologies in the oesophagus, stomach, duodenum, and jejunum after the administration of pembrolizumab for non-small cell lung cancer.