CTLA4 and gastric cancer: Also, our analysis demonstrates that EBV+ GCs with GCLS morphological features is the biological subgroup that would more likely respond to immunotherapy, as they present higher PD-1 expression, the key immunotherapy target in GC, together with Dies1/VISTA and CTLA4. These observations support the ongoing GC clinical trials and highlight GCLS as a useful feature to stratify patients for targeted immunotherapies.