Neoadjuvant CTLA-4/PD-(L)1 Blockade Versus Surgery +/− Chemotherapy in Deficient Mismatch Repair/Microsatellite Instability–High Resectable Gastroesophageal Adenocarcinoma: Individual Patient Data Pooled Analysis

In resectable dMMR/MSI-H GEA, neoadjuvant ICIs significantly increase pathologic response and downstaging versus FLOT, with comparable EFS/OS with surgery with or without chemotherapy. The higher proportion of ypN0 and lack of ypT4 after neoadjuvant ICIs versus FLOT should drive preoperative treatment choices in clinical high-risk disease. The high proportion of pCR/MPR with ICIs provides rationale for exploring organ-sparing surgery or nonoperative management.