Phase III Study of Rilvegostomig in Combination With Bevacizumab With or Without Tremelimumab as First-line Treatment of Hepatocellular Carcinoma

Inclusion Criteria: * Locally advanced or metastatic and/or unresectable HCC * WHO/ECOG performance status of 0 or 1 * BCLC stage B (that is not eligible for locoregional therapy) or stage C. * Child-Pugh Score class A * At least one measurable target lesion * Participants with active HBV infection must receive antiviral therapy for a minimum of 14 days prior to randomization to show evidence of HBV stabilization or signs of viral response. * Participants with active HCV infection must be well controlled. Participants co-infected with HBV and HCV are not eligible. * Adequate organ and bone marrow function measured during the screening period. * Adequate organ and bone marrow function measured during the screening period * Must not have received prior systemic therapy for intermediate, advanced, or metastatic HCC. * Disease that is not amenable to curative surgical and/or locoregional therapies. For participants who received locoregional therapy for HCC, locoregional therapy must have been completed ≥ 28 days prior to the baseline scan for the current study. Exclusion Criteria: Medical condition * Any evidence of uncontrolled intercurrent diseases * Active or prior documented autoimmune or inflammatory disorders requiring chronic treatment with steroids or other immunosuppressive treatment * History of another primary malignancy * Persistent toxicities caused by previous anti-cancer therapy excluding alopecia, not yet improved to Grade ≤ 1 or baseline. * Clinically meaningful ascites, pleural effusion, or pericardial effusion requiring non-pharmacologic intervention to maintain symptomatic control within 6 months prior to the first scheduled dose. * History of active primary immunodeficiency or active infection * History of hepatic encephalopathy * Current or recent (within 10 days of first dose of study treatment) use of aspirin (≥ 325 mg/day) or treatment with dipyridamole, ticlopidine, clopidogrel, and cilostazol * Current or recent (within 10 days prior to study treatment start) use of full-dose oral or parenteral anticoagulants or thrombolytic agents for therapeutic (as opposed to prophylactic) purposes is ineligible * History of significant bleeding disorders, vasculitis, or a significant bleeding episode from the GI tract within 6 months prior to study randomization. * Participants with untreated or incompletely treated varices with bleeding or high-risk (red wale signs or other high-risk factors) for bleeding. HCC related * Known fibrolamellar HCC, sarcomatoid HCC, or mixed cholangiocarcinoma and HCC. * Central nervous system metastases or spinal cord compression (including asymptomatic and adequately treated disease) * Prior treatment with anti-CTLA-4 and/or anti-TIGIT. * Radiotherapy within 28 days and abdominal/ pelvic radiotherapy within 60 days prior to initiation of study treatment, except palliative radiotherapy to bone lesions within 7 days prior to initiation of study treatment