Durvalumab and Tremelimumab as First Line Treatment in Participants With Advanced Hepatocellular Carcinoma (HCC)

* Confirmed unresectable HCC based on histopathological findings (prior histological verification confirming HCC is acceptable), or radiological findings in participants with cirrhosis where histopathological confirmation is not clinically feasible* Must not have received prior systemic therapy for HCC * Participants expected to live 12 weeks or more * At least 1 measurable lesion, not previously irradiated, that can be accurately measured at baseline as ≥ 10 mm in the longest diameter with CT or MRI, and that is suitable for accurate repeated measurements as per RECIST 1.1 guidelines * Must not be eligible for LRT for unresectable HCC. * Barcelona Clinic Liver Cancer (BCLC) stage B (that is not eligible for locoregional therapy LRT) or stage C * Child-Pugh Score classification on liver disease and WHO/ECOG PS at enrolment complying one of the following:

1. Child-Pugh score B7 or B8 with a WHO/ECOG PS of 0-1 at enrolment, without main trunk portal vein thrombosis. 2. Child-Pugh class A with a WHO/ECOG PS of 2 at enrolment, without main trunk portal vein thrombosis (ie, ECOG PS 2 participants with main portal vein tumour thrombosis are excluded from this study). 3. Child-Pugh class A with WHO/ECOG PS of 0-1 at enrolment and with chronic main trunk portal vein thrombosis * Participants with hepatitis B virus (HBV) infection must be treated with antiviral therapy prior to enrolment. * Participants with hepatitis C virus (HCV) infection must have confirmed diagnosis of HCV characterized by the presence of detectable HCV RNA or anti-HCV upon enrolment * Adequate organ and bone marrow function * Negative pregnancy test (serum) for women of childbearing potential. * Female participants must be 1 year post-menopausal, surgically sterile, or using one highly effective form of birth control * Male and Female participants and their partners must use an acceptable method of contraception. * Body weight \>30 kg