A Study Evaluating Atezolizumab and Bevacizumab, With or Without Tiragolumab, in Participants With Untreated Locally Advanced or Metastatic Hepatocellular Carcinoma (HCC) (IMbrave152)

The purpose of this study is to assess the efficacy and safety of tiragolumab, an anti-TIGIT monoclonal antibody, when administered in combination with atezolizumab and bevacizumab as first-line treatment, in participants with unresectable, locally advanced or metastatic HCC. Per amendment version 5, following a memo issued by the Sponsor, participants receiving treatment in the atezolizumab plus bevacizumab plus tiragolumab arm are recommended to discontinue tiragolumab treatment unless the investigator decides the benefit outweighs the risk. Participants receiving treatment in atezolizumab plus bevacizumab plus placebo arm must discontinue placebo treatment. Participants may continue receiving active treatment(s) per protocol until loss of clinical benefit or unacceptable toxicity, whichever occurs first.