Our recruitment case on 11/18/29 was about an older patient with urothelial carcinoma on pembrolizumab (PD-1 checkpoint inhibitor) presenting with nausea, vomiting and decreased PO intake. DDx was complicated by the fact that they had CKD 5 not on dialysis (with acute mild worsening of his AKI) but they were ultimately diagnosed with PD-1 induced hypophysitis – rare complication of PD-1 inhibitors (more common with combination of checkpoint inhibitors). Some more information here: Checkpoint hypophysitis – 11.18

Take home points:

• Vomiting is a reflex with 4 main activating pathways

• Treatment can be tailored to the activating pathway

• Avoidance of anchoring and rethinking DDx when patients don’t improve

• Checkpoint inhibitors are commonly used and list of indications is expanding

• Most organ systems can be affected by toxicity, always have IrAEs in your differential diagnosis