Neoadjuvant nivolumab plus ipilimumab and adjuvant nivolumab for localized dMMR/MSI-H G/GEJ adenocarcinoma

Surgery plus perioperative platinum-based chemotherapy is standard of care for resectable gastric/gastroesophageal junction (G/GEJ) adenocarcinoma. Perioperative chemotherapy remains debatable for G/GEJ adenocarcinoma with deficient mismatch repair/microsatellite instability high (dMMR/MSI-H). The multicenter phase 2 NEONIPIGA study in France evaluated neoadjuvant nivolumab plus ipilimumab and adjuvant nivolumab for localized dMMR/MSI-H G/GEJ adenocarcinoma. Among the patients who underwent surgery, the pCR rate was 59%, without unexpected immune-related adverse events or postoperative morbidity. One patient died 3 days after surgery (not related to the neoadjuvant ICIs). At the end of follow-up all other patients were alive and recurrence-free.