RecruitingPhase 2Drug trialSimvastatin Efficacy in ARID1A Mutated Advanced gastroESophageal Carcinoma Treated With ImmunotherapyThe investigators hypothesize that simvastatin (SIM) may improve the efficacy of first- line Nivolumab and Oxaliplatin-based chemotherapy, extending progression-free survival (PFS) as compared with Nivolumab and chemotherapy alone in patients with HER2 negative and ARID1A mutated advanced gastrooesophageal carcinoma (aGEC). Correlative mechanistic studies on tissue and blood samples, could help understanding the evolutionary dynamics of tumors in response to therapy thus optimizing the treatment approach and adding new insight into the antitumor mechanism of the combination approach.