To compare the impact on recurrence risk of adjuvant Sintilimab (a recombinant fully human anti-PD-1 monoclonal antibody) for patients with hepatocellular carcinoma and microvascular invasion (MVI) after hepatectomy.

This study is a prospective, multicenter, open-label, randomized controlled clinical trial, aiming to recruit 360 patients with MVI-positive HCC who have undergone surgical resection. The patients will be randomly divided into three groups: the first group will receive six months of adjuvant therapy with Sintilimab (200 mg every three weeks for a total of 9 cycles), the second group will receive one year of adjuvant therapy with Sintilimab (200 mg every three weeks for a total of 18 cycles), and the Active surveillance group will be closely followed postoperatively. A maximum of one postoperative adjuvant TACE is permitted.

Inclusion Criteria:

• Subjects with a histopathological diagnosis of HCC
• Undergone a curative resection
• Pathologically confirmed HCC with microvascular invasion (MVI)
• Aged 18-75 years
• No previous systematic treatment and locoregional therapy for HCC prior to randomization
• Absence of major macrovascular invasion
• No extrahepatic spread
• Full recovery from Curative resection within 4 weeks prior to randomization
• Child-Pugh: Grade A or B(7)
• ECOG-PS score: 0 or 1
• Subjects with HCV- RNA (+) must receive antiviral therapy
• Adequate organ function

Exclusion Criteria:

• Known fibrolamellar HCC, sarcomatoid HCC, mixed cholangiocarcinom or recurrent HCC
• Any preoperative treatment for HCC including local and systemic therapy
• Have received more than 1 cycle of adjuvant TACE following surgical resection
• Any acute active infectious diseases, active or history of autoimmune disease, or immune deficiency
• Known history of serious allergy to any monoclonal antibody or targeted anti-angiogenic drug
• Subjects with inadequately controlled hypertension or history of hypertensive crisis or hypertensive encephalopathy
• Cardiac clinical symptom or cardiovascular disease that is not well controlled
• Thrombosis or thromboembolic event within 6 months prior to the start of study treatment
• Any persistent serious surgery-related complications; esophageal and/or gastric variceal bleeding within 6 months
• Abdominal fistula, gastrointestinal perforation or intraperitoneal abscess within 6 months prior to the start of study treatment
• Inability or refusal to comply with the treatment and monitoring