Exploring the Efficacy and Safety of Tislelizumab in Combination With S-1 in the Treatment of Patients With Postoperative Recurrent High-risk Intrahepatic Cholangiocarcinoma

Inclusion Criteria:

• 18-75 years old, male and female;

• Intrahepatic cholangiocarcinoma was pathologically confirmed after R0 or R1resection. Patients were also pathologically confirmed to have one of the followinghigh-risk factors (i.e., positive margins, multiple tumor nodes, positive lymphnodes, positive perineural infiltration, intrahepatic cholangiocarcinoma >5 cm indiameter, and combined vascular invasion);

• Enhanced computed tomography (CT) scans of the chest, abdomen, and pelvis wererequired within 30 days prior to surgery to demonstrate the absence of distant tumormetastases;

• No history of any chemotherapy, radiotherapy, immunotherapy or interventionaltherapy within 3 months prior to surgical resection;

• Child-Pugh grade A or B, ECOG score 0-1;

• Normal organ function prior to drug administration: ANC ≥1.5×10^9/L, Hemoglobin ≥90g/L, PLT >50*10^9/L, serum creatinine (SCr) ≤ 1.5 times the upper limit of normal (ULN) or creatinine clearance ≥50 ml/min (Cockcroft-Gault formula); total bilirubin (TBIL) ≤2 times the upper limit of normal (ULN); glutamine transaminase (AST) orglutamine transaminase (ALT) levels ≤3 times the ULN; urinary protein <2+ (ifurinary protein) upper limit of normal (ULN); albumin transaminase (AST) or alaninetransaminase (ALT) levels ≤3 times upper limit of normal (ULN); urine protein <2+ (if urine protein ≥2+, 24-hour urine protein quantification must show ≤1g ofprotein); and adequate surgical biliary drainage with no signs of infection.

• Normal coagulation function: a. International normalized ratio INR ≤ 1.5 x ULN; b.Partial thromboplastin time APTT ≤ 1.5 x ULN; c. Prothrombin time PT ≤ 1.5 ULN;

• In case of hepatitis B virus (HBV) infection: if HBsAg-positive, HBV-DNA testing isrequired and HBV-DNA must be <2000 IU/mL and willing to receive antiviral therapythroughout the study period; hepatitis C virus (HCV)-RNA-positive patients must haveHCV-RNA <1×10^3copy/mL and must receive antiviral therapy according to treatmentguidelines.

• No major abnormalities in heart, lung or kidney function;

• No history of gastrointestinal hemorrhage;

• Sign the informed consent form.

Exclusion Criteria:

• The tumor is not completely resected, or the pathological diagnosis suggestsnon-intrahepatic cholangiocarcinoma such as hepatocellular carcinoma, mixedhepatocellular carcinoma, and hepatoportal cholangiocarcinoma;

• Pregnant or breastfeeding women;

• Combined with other malignant tumors;

• Have any active autoimmune disease or a history of autoimmune disease;

• Uncontrolled clinically significant cardiac disease, including but not limited tothe following: (1) > NYHA II congestive heart failure; (2) unstable angina pectoris; (3) myocardial infarction within the last 1 year; (4) clinically significantsupraventricular arrhythmia or ventricular arrhythmia requiring treatment orintervention;

• The patient has a congenital or acquired immunodeficiency;

• Uncontrollable infection > grade 2 (NCI-CTC version 5.0);

• Psychopaths;

• Patients have participated in other clinical trials within the past three months;

• Postoperative patients receiving other targeted agents, immunotherapy such as PD-1antibodies, and FOLFOX systemic chemotherapy;

• Patients who are not suitable to participate in the study as determined by theinvestigator.