PRJNA766700
E203K Mutation in MAP2K1 (MEK1) Causes Resistance to PD-1 Blockade and Responds to Trametinib in Epstein-Barr Virus Associated Gastric Cancer
Epstein-Barr virus associated gastric cancer (EBVaGC) is characterized by higher lymphocytic infiltration, predicting sensitivity to immunotherapy. However, no clinical data is available to investigate its acquired resistance. We describe a patient with EBVaGC underwent acquired resistance to PD-1 blockade after partial response by chemotherapy plus sintilimab, a fully humanized anti-PD-1 monoclonal antibody. Re-biopsy revealed a secondary gain-of-function mutation in diver gene MAP2K1/MEK1 (E203K) was acquired.