This is a phase III, multicenter, open-label, randomized controlled trial designed to evaluate the efficacy and safety of arterially directed therapy in combination with tislelizumab plus lenvatinib compared with gemcitabine and cisplatin (GEMCIS) in combination with tislelizumab as first-line treatment for patients with unresectable intrahepatic cholangiocarcinoma.

Approximately 140 eligible patients with histologically confirmed unresectable intrahepatic cholangiocarcinoma without extrahepatic metastasis will be enrolled and randomized in a 1:1 ratio to receive either TACE plus tislelizumab and lenvatinib or GEMCIS plus tislelizumab. In the TACE-based treatment arm, hepatic arterial infusion chemotherapy with gemcitabine and cisplatin may be administered during or after TACE at the investigator's discretion according to the protocol.

The primary endpoint is overall survival. Secondary endpoints include progression-free survival, time to progression, objective response rate, disease control rate, safety, and quality of life.

Inclusion Criteria:

1. Age ≥18 years.

2. Histologically confirmed intrahepatic cholangiocarcinoma that is unresectable or recurrent after curative treatment, without extrahepatic metastasis.

3. No prior systemic therapy or transarterial interventional therapy for intrahepatic cholangiocarcinoma.

4. At least one measurable intrahepatic lesion according to RECIST v1.1.

5. ECOG performance status of 0 or 1.

6. Child-Pugh class A liver function.

7. Life expectancy ≥3 months.

8. Adequate hematologic, hepatic, renal, and thyroid function within 14 days before study start, defined as:

   • Absolute neutrophil count ≥1.5 × 10⁹/L;
   • Platelet count ≥75 × 10⁹/L;
   • Hemoglobin ≥90 g/L;
   • Serum albumin ≥30 g/L;
   • Total bilirubin ≤1.5 × upper limit of normal;
   • AST and ALT <1.5 × upper limit of normal, and ALP <4 × upper limit of normal;
   • TSH <1 × upper limit of normal, with T3 and T4 within the normal range;
   • Serum creatinine <1.5 × upper limit of normal and creatinine clearance ≥60 mL/min.

Exclusion Criteria:

1. Diffuse infiltrative liver lesions.
2. Contraindications to TACE.
3. Allergy to intravenous contrast agent.
4. pregnant or breastfeeding women, or participants planning pregnancy within 2 years / unwilling to use effective contraception.
5. Patients with HIV or syphilis infection.
6. Patients with concurrent malignancies or other malignancies within 5 years before enrollment.
7. History of allogeneic organ transplantation.
8. Severe dysfunction of the heart, kidney, or other organs.
9. Severe clinically active infection > grade 2 according to NCI-CTC v5.0.
10. Psychiatric illness that may affect the informed consent process; Inability to take oral medications; Participation in another drug clinical trial within 12 months before enrollment.

Individual participant data will not be shared due to privacy, ethical, and regulatory considerations.