A Study to Assess the Dose, Adverse Events, and Change in Disease Activity of Livmoniplimab as an Intravenous (IV) Solution in Combination With Budigalimab as an IV Solution in Adult Participants With Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is a common cancer worldwide and a leading cause of cancer-related death. The majority of participants first presenting with HCC have advanced unresectable or metastatic disease. The purpose of this study is to evaluate the optimized dose, adverse events, and efficacy of livmoniplimab in combination with budigalimab. Livmoniplimab is an investigational drug being developed for the treatment of HCC. There are 2 stages to this study. In Stage 1, there are 3 treatment arms and participants will be randomized in a 1:1:1 ratio. Participants will either receive livmoniplimab (at different doses) in combination with budigalimab (another investigational drug), atezolizumab in combination with bevacizumab, or tremelimumab in combination with durvalumab. In Stage 2, there are 2 treatments arms and participants will be randomized in a 1:1 ratio. Participants will either receive livmoniplimab (optimized dose) in combination with budigalimab or tremelimumab in combination with durvalumab. Approximately 660 adult participants will be enrolled in the study across 185 sites worldwide. Stage 1: In arm 1, participants will receive intravenously (IV) infused livmoniplimab (Dose 1) in combination with IV infused budigalimab, every 3 weeks. In arm 2, participants will receive IV infused livmoniplimab (Dose 2) in combination with IV infused budigalimab, every 3 weeks. In Arm 3 (control), participants will receive the investigator's choice: IV atezolizumab in combination with IV bevacizumab every 3 weeks or single dose IV tremelimumab in combination with IV durvalumab every 4 weeks. Stage 2: In arm 1, participants will receive IV infused livmoniplimab (optimized dose) in combination with IV infused budigalimab, every 3 weeks. In Arm 2 (control), participants will receive single dose IV tremelimumab in combination with IV durvalumab every 4 weeks. All participants will continue treatment until disease progression or discontinuation criteria are met, whichever occurs first. The estimated duration of this study is about 56 months. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic and may require frequent medical assessments, blood tests, questionnaires, and scans.