Background: Hepatocellular carcinoma (HCC) is of high incidence and mortality rate in China, with nearly half of them are diagnosed as advanced or metastatic stage at the initial diagnosis. First-line treatment options for patients with advanced disease previously included tyrosine kinase inhibitors and immune checkpoint inhibitors in combination with vascular endothelial growth factor. Recently, the phase III HIMALAYA trial investigated the STRIDE regimen, tremelimumab 300mg × 1 dose and durvalumab 1500mg every 4 weeks, compared to sorafenib in previously untreated locally advanced or metastatic HCC patients, and resulted in significantly improved overall survival (OS) (16.4 mos vs 13.8mos, HR=0.78) and a well-tolerated safety profile (≥grade 3 treatment-related adverse events 25.8% vs 36.9% ). Notably, the HIMALAYA trial did not enroll subject from mainland China and excluded patients with class Child-Pugh B liver dysfunction or ECOG performance status (PS) 2. We hypothesize the STRIDE regimen will be safe and well tolerated in Chinese patients with locally advanced or metastatic HCC with Child-Pugh class A or B liver dysfunction or ECOG PS 0-2. In addition, the study will also assess efficacy and explore biomarkers. Methods: This will be an open label, multi-center phase IIIb study investigating the safety and efficacy of the STRIDE regimen in Chinese unresectable HCC patients without prior systemic therapy. Patients with Child-Pugh A liver dysfunction and ECOG PS 0-1 will be enrolled in cohort 1, while patients with Child-Pugh B liver dysfunction or ECOG PS 2 will be enrolled in cohort 2. Patients with main portal vein tumor thrombosis (Vp4), clinically significant ascites or hepatic encephalopathy, or active or prior documented gastrointestinal bleeding within 12 months will be excluded. We plan to enroll 300 patients with the primary endpoint of grade 3-5 adverse event (AE) rate by CTCAE v5.0 and adverse events of special interest (AESI). Secondary endpoints include objective response rate (ORR), disease control rate (DCR), progression free survival (PFS), OS, OS rate at 6 months and 12 months. Patients of both cohorts will receive a single dose of tremelimumab 300 mg and durvalumab 1500 mg at Cycle 1 (Week 0), followed by durvalumab 1500 mg monotherapy every 4 weeks until confirmed disease progression or unacceptable toxicity. Archival or fresh tumor biopsy will be required at baseline. The trial is currently screening eligible subjects. Clinical trial information: CTR20222433.