Tumor recurrence is the leading cause of death and a major bottleneck for long-term survival in patients with hepatocellular carcinoma (HCC). Therefore, there is an urgent clinical need for effective postoperative adjuvant therapies to reduce postoperative recurrence and improve long-term survival, especially for HCC patients with high-risk factors. However, no standard adjuvant treatment regimen has been established so far, and domestic and international guidelines have not reached a consensus on relevant recommendations. It is generally recognized that postoperative antiviral therapy with nucleoside analogues and interferon yields definite benefits for patients with HBV- or HCV-related HCC, particularly those in Asian populations. Some interventions have been proven ineffective. For instance, the majority of studies have demonstrated that postoperative chemotherapy fails to bring survival benefits and may even lead to worse prognosis in HCC patients. Besides, multiple treatment modalities including transarterial chemoembolization (TACE), radiotherapy, targeted therapy and immunotherapy are still under investigation.

MVI has been well documented as a strong high-risk factor for postoperative recurrence of HCC. The presence of MVI indicates the capacity of tumor cells for local invasion and distant metastasis. According to the number and location of microscopic tumor foci observed under pathological microscopy, MVI is classified into three grades: (1) M0: No microscopic tumor foci detected; (2) M1: No more than 5 microscopic foci within 1 cm adjacent to the primary tumor; (3) M2: More than 5 microscopic foci or foci located beyond 1 cm from the primary tumor. A retrospective study from Zhongshan Hospital, Fudan University enrolled 661 HCC patients who developed recurrence within 5 years after curative resection, and reported that the rate of MVI positivity was 31.6% among these recurrent cases. Another retrospective study conducted at Eastern Hepatobiliary Surgery Hospital of Shanghai involving 496 HCC patients showed that patients with MVI had significantly lower recurrence-free survival (RFS) and overall survival (OS) compared with those without MVI. A series of studies have been carried out to explore postoperative adjuvant treatments for resectable HCC patients complicated with MVI. A phase III randomized controlled trial conducted by Wei et al. revealed that for patients with single resectable HCC (tumor ≥ 5 cm) combined with MVI, postoperative adjuvant TACE (1 to 2 cycles) achieved a median disease-free survival (DFS) of 17.45 months (95% CI: 11.99-29.14), versus 9.27 months (95% CI: 6.05-13.70) in the active surveillance group (HR=0.70, p=0.020). In addition, Li et al. evaluated the efficacy of postoperative adjuvant FOLFOX-based hepatic arterial infusion chemotherapy (HAIC) in resectable HCC patients with MVI. The results demonstrated that adjuvant HAIC could significantly prolong DFS, with a median DFS of 20.3 months versus 10.0 months (p=0.001). Collectively, active postoperative intervention is clinically meaningful for resectable HCC patients with MVI.

In recent years, tumor immunotherapy represented by immune checkpoint inhibitors, including antibodies against programmed death-1 (PD-1), programmed death ligand-1 (PD-L1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), has gradually become a key therapeutic strategy for malignancies. Tumor cells can inhibit T cell activity and evade immune surveillance by expressing immune checkpoint ligands. Blockade of these immune checkpoints can enhance the proliferation, survival and cytotoxicity of T cells, thereby exerting anti-tumor effects. Anti-PD-1/PD-L1 antibodies have exhibited favorable efficacy in a variety of solid tumors.

Given the high postoperative recurrence risk of resectable HCC with MVI and the lack of consensus on standard adjuvant regimens, as well as the proven efficacy of PD-1 monoclonal antibodies and HAIC in this setting in previous randomized controlled trials, we designed a prospective, single-center, open-label, phase II cohort study. This study aims to preliminarily evaluate the efficacy and safety of eparlitozoviril (dual PD-1/CTLA-4 immunotherapy), compared with active surveillance, in resectable HCC patients with MVI. The findings of this study may provide evidence for the optimization of postoperative adjuvant treatment for HCC.

Inclusion Criteria:

• Voluntarily enroll in the trial and provide signed written informed consent.
• Aged between 18 and 75 years (inclusive), male or female.
• Underwent curative resection for hepatocellular carcinoma 4 to 6 weeks prior to enrollment.
• Pathologically confirmed hepatocellular carcinoma (HCC) with microvascular invasion (MVI).
• No evidence of recurrence or metastasis confirmed by imaging examinations at least 4 weeks after surgery.
• Liver function classified as Child-Pugh Class A (score: 5-6 points).
• Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score of 0 or 1.
• For females of childbearing potential (non-menopausal or not surgically sterilized): serum pregnancy test must be negative within 7 days before administration of study drug.
• All female and male participants of childbearing potential must use effective contraception during study drug treatment and for 60 days after the last dose.
• Adequate function of major organs, meeting the following criteria (no blood transfusion or G-CSF administered within 14 days before screening; no albumin used within 14 days before screening):

Hematology:

1. Hemoglobin ≥ 90 g/L

2. Absolute neutrophil count (ANC) ≥ 1.5×10⁹/L

3. Platelet count ≥ 75×10⁹/L

   Serum biochemistry:

4. Albumin ≥ 28 g/L

5. Total bilirubin ≤ 1.5 × upper limit of normal (ULN)

6. Aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 3 × ULN

7. Creatinine ≤ 1.5 × ULN

Coagulation function:

International normalized ratio (INR) or prothrombin time (PT) ≤ 1.5 × ULN; Activated partial thromboplastin time (APTT) ≤ 1.5 × ULN

Exclusion Criteria:

• Pathologically confirmed mixed hepatocellular carcinoma and intrahepatic cholangiocarcinoma (HCC-ICC).

• Positive surgical margin or tumor rupture.

• History of other malignancies within the past 5 years, except for patients who have received curative treatment with no evidence of disease for 5 consecutive years. This 5-year exclusion rule does not apply to patients with completely resected basal cell carcinoma, squamous cell carcinoma of the skin, superficial bladder cancer, cervical carcinoma in situ or other carcinoma in situ.

• History of congenital or acquired immunodeficiency disorders, either current or prior.

• Active or documented history of autoimmune or inflammatory diseases (including but not limited to autoimmune hepatitis, interstitial lung disease, inflammatory bowel disease, systemic lupus erythematosus, vasculitis, uveitis, hypophysitis, hyperthyroidism, hypothyroidism, and asthma requiring bronchodilator therapy). Patients with vitiligo or childhood asthma fully resolved without any intervention in adulthood are eligible.

• History of severe psychiatric disorders.

• Prior allogeneic stem cell or organ transplantation, excluding corneal transplantation.

• Prior treatment with immune modulators such as anti-PD-1, anti-PD-L1 or anti-CTLA-4 agents before enrollment.

• Prior systemic anti-tumor therapy (including traditional Chinese medicines with anti-tumor indications) before enrollment. Patients are excluded if the interval between completion of prior therapy and study drug administration is less than 2 weeks or 5 half-lives of the prior drug (whichever is longer), or if adverse events related to prior therapy have not recovered to CTCAE Grade 1 or lower.

• Received systemic immunosuppressive drugs within 2 weeks prior to enrollment, or anticipated need for systemic immunosuppressive drugs during the study, except for the following:

  1. Intranasal, inhaled, topical or local injected corticosteroids (e.g., intra-articular injection);
  2. Systemic corticosteroids at a daily dose equivalent to ≤ 10 mg prednisone;
  3. Corticosteroids used for prophylaxis of hypersensitivity reactions.

• Known or suspected history of hypersensitivity to chimeric/humanized antibodies or fusion proteins, or allergy to excipients of the study drug.

Uncontrolled hepatic encephalopathy, hepatorenal syndrome, ascites, pleural effusion or pericardial effusion.

• Clinically significant cardiovascular diseases, including but not limited to acute myocardial infarction, severe/unstable angina or coronary artery bypass grafting within the previous 6 months; congestive heart failure (New York Heart Association [NYHA] Class > II); uncontrolled arrhythmia or arrhythmia requiring pacemaker implantation; uncontrolled hypertension (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg).

Active infections:

1. Positive human immunodeficiency virus (HIV-1/2 antibody);

2. Active hepatitis C (positive HCV antibody or HCV RNA ≥ 10³ copies/mL accompanied by abnormal liver function);

3. Active tuberculosis;

4. Other uncontrolled active infections (CTCAE Version 5.0 > Grade 2).

   • Other clinically significant clinical or laboratory abnormalities judged by the investigator to compromise safety assessment, such as uncontrolled diabetes, chronic kidney disease, peripheral neuropathy ≥ CTCAE Grade 2, thyroid dysfunction, etc.
   • Unresolved post-operative conditions, such as unhealed surgical incisions or severe post-operative complications.
   • Received any live attenuated vaccine within 4 weeks prior to enrollment or planned to receive such vaccines during the study.
   • History of alcohol, psychotropic substances or other drug abuse within the previous 6 months.
   • Participation in other investigational drug or medical device clinical trials within 4 weeks prior to enrollment.
   • Inability to comply with the study treatment or scheduled follow-up visits.
   • Any other conditions that make the patient ineligible for enrollment as determined by the investigator.