A Study Evaluating Atezolizumab, With or Without Bevacizumab, in Patients With Unresectable Hepatocellular Carcinoma and Child-Pugh B7 and B8 Cirrhosis (Kirros)

General Inclusion Criteria: Locally advanced or metastatic and/or unresectable HCC with diagnosis confirmed by histology/cytology or clinically by American Association for the Study of Liver Diseases (AASLD) criteria in cirrhotic patients Disease that is not amenable to curative surgical and/or locoregional therapies No prior systemic treatment (including systemic investigational agents) for locally advanced or metastatic and/or unresectable HCC Measurable disease (at least one untreated target lesion) according to RECIST v1.1 ECOG Performance Status of 0-2 within 7 days prior to initiation of study treatment Child-Pugh B7 or B8 cirrhosis at screening and within 7 days prior to study treatment Adequate hematologic and end-organ function Life expectancy of at least 12 weeks Female participants of childbearing potential must be willing to avoid pregnancy and egg donation General Exclusion Criteria: Pregnancy or breastfeeding Prior treatment with CD137 agonists or immune checkpoint blockade therapies Treatment with investigational therapy within 28 days prior to initiation of study treatment Treatment with locoregional therapy to liver within 28 days prior to initiation of study treatment, or non-recovery from side effects of any such procedure Treatment with systemic immunostimulatory agents Treatment with systemic immunosuppressive medication Treatment with a live, attenuated vaccine within 4 weeks prior to initiation of study treatment Inadequately controlled hypertension Active or history of autoimmune disease or immune deficiency History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis on screening chest computed tomography (CT) scan History of malignancy other than HCC within 3 years prior to screening, with the exception of malignancies with a negligible risk of metastasis or death Known fibrolamellar HCC, sarcomatoid HCC, other rare HCC variant, or mixed cholangiocarcinoma and HCC Symptomatic, untreated, or actively progressing central nervous system (CNS) metastases Prior allogeneic stem cell or solid organ transplantation Listed for liver transplantation Co-infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) Untreated or incompletely treated esophageal and/or gastric varices with bleeding or that are at high risk for bleeding A prior bleeding event due to esophageal and/or gastric varices within 6 months prior to initiation of study treatment Grade ≥3 hemorrhage or bleeding event within 6 months prior to initiation of study treatment History of hepatic encephalopathy requiring hospitalization or treatment escalation within 6 months prior to study treatment, or any continued symptoms of encephalopathy despite medical management History, planned, or recommended placement of transjugular intrahepatic portosystemic shunt (TIPS) History of ascites requiring therapeutic paracentesis over the last 3 months History of spontaneous bacterial peritonitis within last 12 months