We have previously reported that MDM2 amplification can be associated with hyperprogression after treatment with anti–PD-1/PD-L1 agents.22 We describe herein a 36-year-old woman (not previously reported) with adenocarcinoma of the gastro-esophageal junction who had stable disease (SD) while receiving second-line therapy with fluorouracil, oxaliplatin, and panitumumab (Fig 3, left and middle). The gene discussed is CD274; the disease is adenocarcinoma.