Nivolumab in Combination With Chemotherapy for FGFR2-positive Metastatic Gastric Cancer

Inclusion Criteria: * Previously untreated, unresectable advanced or metastatic gastric adenocarcinoma * Measurable lesions according to the RECIST 1.1 criteria * PD-L1 Combined Positive Score (CPS) of five or more assessed by Dako PD-L1 immunohistochemistry 28-8 pharmDx assay * Positive FGFR2 overexpression status by immunohistochemistry defined as exhibiting any moderate (2+) to strong (3+) membranous staining in more than 1% of tumor cells * Possibility to assess the amplification of FGFR2 * HER2-negative status * ECOG PS 0-2 * Age \>= 18 years old * Adequate function of organs * Absence of any psychological, family, social or geographical circumstances that could potentially serve as obstacles to the implementation of the study * Signed Informed Consent Exclusion Criteria: * Participation in another clinical study and concomitant treatment with any research drug or any study of antitumor therapy, including radiation, within 28 days before inclusion in this study * Presence of metastases in the central nervous system and / or carcinoma of the meninges at the time of inclusion in the study * Presence or history of present signs of any condition, therapy or laboratory abnormalities that could limit the interpretation of the results of this study * Any malignant tumor within the previous 5 years, with the exception of adequately cured cervical cancer in situ or squamous cell skin cancer, or basal cell skin cancer with limited growth, subject to adequate control over the course of this disease * Pregnancy * Known positive status for human immunodeficiency virus (HIV) or active hapatitis B and C * Surgery within 7 days before the first dose of the study drug * Signs of bleeding or hemorrhagic diathesis