RecruitingPhase 2Drug trialEfficacy and Safety of Anti-PD-1, Thymalfasin, and SOX in Neoadjuvant Treatment of cStage III Gastric/Gastroesophageal Junction AdenocarcinomaThis Phase II clinical study is a prospective, open-label, single-arm trial designed to evaluate the efficacy and safety of combining anti-PD-1 therapy (Serplulimab) with thymalfasin and the SOX chemotherapy regimen as a neoadjuvant treatment for patients with clinical stage III gastric or gastroesophageal junction(GEJ) adenocarcinoma.