Safety and Efficacy of Systemic Chemotherapy Plus PD-1 Inhibitor in Combination With Bevacizumab in Gastric Cancer With Peritoneal Metastasis

Inclusion Criteria: * 18 to 75 years patients histologically or cytologically confirmed the presence of GC or gastroesophageal junction tumor with PM (HER2 negative). The ECOG performance status is 0-1 and the expected survival time is more than 3 months. Did not receive any therapy for GC within the last six months (chemotherapy, radiation therapy, or both). Exclusion Criteria: * Principal exclusion criteria: The obstruction of the cardia and pylorus affects the patient\'s eating and gastric emptying, or has difficulty swallowing tablets. HER2-positive GC and gastroesophageal junction tumors. Subject with other malignancies, except for non-melanoma skin cancer or in-situ cervical carcinoma under adequate treatment, or other treated malignancies without evidence of recurrence for 5 years. Previously received the following therapies: anti-PD-1, anti-PD-L1 or anti-PD-L2 drugs or drugs that stimulate or co-inhibit T cell receptors (eg, CTLA-4, OX-40, CD137). Received systemic treatment with Chinese medicines or immunomodulatory drugs (including thymosin, interferon, interleukin, except for local use to control pleural effusion) with anti-tumor indications within 2 weeks before the first administration; Active autoimmune disease requiring systemic therapy (eg, disease-modifying drugs, glucocorticoids, or immunosuppressants) occurred within 2 years prior to first dose; Replacement therapy (such as thyroxine, insulin, or physiological glucocorticoids for adrenal or pituitary…