Study Evaluating the Combination of Bemarituzumab + FLOT Chemotherapy in Perioperative Setting for Resectable Stage cT2-T4a or N+ Gastric and GEJ Adenocarcinoma Overexpressing FGFR2b

"Bemarituzumab (IV administration) over 30 min (+/- 10min) at C1D1 to C8D1 + 15 mg/kg of bodyweight + single additional dose of 7,5 mg/kg at C1D8~\+ FLOT regimen~* Fluorouracil for solution for infusion (IV administration) as a continuous IV infusion approximately 24 hours 2600 mg/m²~* Leucovorin (folinic acid) solution for infusion (IV administration) over 120 min on the first day, 200 mg/m²~* Oxaliplatin concentrate for solution for infusion (IV administration) over 120 min on the first day, 85 mg/m²~* Docetaxel concentrated for solution for infusion (IV administration) over 60 min on the first day, 50 mg/m²"