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 co…