Perioperative Treatment in Resectable Gastric Cancer With Spartalizumab (PDR001) in Combination With Fluorouracil, Leucovorin, Oxaliplatin, and Docetaxel (FLOT)

Inclusion Criteria: * Age ≥ 18 years * Untreated localized gastric or GEJ adenocarcinoma considered resectable (clinical stage ≥cT2 and/or cN+ and no metastasis) * Histologically confirmed adenocarcinoma * ECOG performance status score of 0 or 1 * Tumor tissue must be provided for biomarker analyses (fresh or archival with an FFPE tissue block) * All subjects must consent to allow the acquisition of blood samples for performance of correlative studies * Screening laboratory values must meet the following criteria: * WBC ≥ 2000/ mm³ * Neutrophils ≥ 1500/ mm³ * Platelets ≥ 100 000/ mm³ * Hemoglobin ≥ 9.0 g/dL * Bilirubin ≤ 1.5 x ULN, AST and ALT ≤ 3 x ULN * Measured or calculated creatinine ≥ 50 ml/min clearance (CrCl) (using the Cockcroft-Gault formula) * Potassium ≥ LLN * Magnesium ≥ LLN * Calcium ≥ LLN * Female subject of childbearing potential must have a negative urine or serum pregnancy test within 72h before study start * Subject in reproductive age must be willing to use adequate contraception during the study and at least 9 months in men and 12 months in women after the last dose of investigational drug. In addition, given the toxicities observed on the male reproductive system, a conservation of gametes will be proposed for men, as usually in routine practice * Subject affiliated to a social security regimen * Patient has signed informed consents obtained before any trial related activities and according to local guidelines Exclusion Criteria: Su…