Intraperitoneal Immune Checkpoint Inhibitor for Malignant Ascites

Inclusion Criteria: * Patients have cyto-/histologically confirmed malignant ascites from gastric, pancreatic or biliary tract adenocarcinoma * Patients have malignant ascites more than 1000ml * Patients have no history of prior intraperitoneal therapy for malignant ascites * Patients have life expectancy of at least 4 weeks * Patients have adequate platelet count ≥ 50,000/ul * Women or men of reproductive potential should agree to use an effective contraceptive method * All patients must be informed of the investigational nature of this study and must sign written informed consents. Exclusion Criteria: * Patients have ascites which is related to causes other than the malignancies * Patients who are receiving intraperitoneal treatment for their malignant ascites including therapeutic paracentesis * Patients with active infection * Patients with bleeding disorders * Patient with active cardiopulmonary disease or history of ischemic heart disease * Patients have intolerant abdominal pain * Patients who have serious concomitant systemic disorders incompatible with the study, i.e. poorly controlled diabetes mellitus, auto-immune disorders, cirrhosis of the liver, and the rest will be at the discretion of in-charged investigator