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)

Stage 1: Number of Participants with Progression-Free Survival (PFS)

PFS is defined as the time from randomization until the first documentation of progressive disease according to RECIST 1.1 as determined by investigators or death from any cause, whichever occurs first.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Duration of Response (DOR) per Investigator

DOR is defined as the time from first confirmed CR or PR until the first documentation of progressive disease according to RECIST 1.1 as determined by investigators or death from any cause, whichever occurs first.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Overall Survival (OS)

OS is defined as the time from randomization until death from any cause.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Number of Participants with Adverse Events (AEs)

An AE is defined as any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product which does not necessarily have a causal relationship with this treatment.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Maximum Plasma Concentration (Cmax) of Livmoniplimab and Budigalimab

Cmax of livmoniplimab and budigalimab.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Time to Cmax (Tmax) of Livmoniplimab and Budigalimab

Tmax of livmoniplimab and budigalimab.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 1: Area Under the Serum Concentration Versus Time Curve (AUC) of Livmoniplimab and Budigalimab

AUC of livmoniplimab and budigalimab.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 2: Number of Participants with Progression-Free Survival (PFS)

PFS is defined as the time from randomization until the first documentation of progressive disease according to RECIST 1.1 as determined blinded independent central review (BICR) or death from any cause, whichever occurs first.

Time frame: Through Study Completion, Up to Approximately 56 Months

Stage 2: Best Overall Response (BOR) of Complete Response (CR)/Partial Response (PR) per BICR

BOR is defined as a participant achieving confirmed CR/PR per RECIST 1.1 as determined by BICR at any time prior to subsequent anticancer therapy.

Time frame: Through Study Completion, Up to Approximately 56 Months

Change from Baseline in the Pain Domain of the European Organization for Research Treatment of Cancer Quality of Life Questionnaire Hepatocellular Carcinoma 18-Question Module (EORTC QLQ-HCC18)

The EORTC QLQ-HCC18 is an 18-item scale that measures hepatocellular carcinoma (HCC)-specific symptoms and health-related quality of life (HRQoL). The Pain Domain contains 2 items where scores are based on a 4-point Likert scale (with 1 = 'not at all' to 4 = 'very much'); scaled scores for each domain ranged from 0-100 with a higher score indicating worse symptoms.

Time frame: Baseline to Week 12

Change from Baseline in the Fatigue Domain of the EORTC QLQ-HCC18

The EORTC QLQ-HCC18 is an 18-item scale that measures HCC-specific symptoms and HRQoL. The Fatigue Domain contains 3 items where scores are based on a 4-point Likert scale (with 1 = 'not at all' to 4 = 'very much'); scaled scores for each domain ranged from 0-100 with a higher score indicating worse symptoms.

Time frame: Baseline to Week 12

Change from Baseline in Physical Function (PF) Domain of the European Organization for Research Treatment of Cancer Quality of Life Questionnaire Core-30 (EORTC QLQ-C30)

The EORTC QLQ-C30 is an 30-item patient-reported questionnaire that measures symptoms and HRQoL. The PF Domain is a functional scale where participants rate items on a 4-point scale (with 1 = 'not at all' to 4 = 'very much'). A change of 5 to 10 points is considered a small change and the lower bound (5) will be used to define the minimum important difference. A change of \>= 10 to \< 20 points is considered a moderate change.

Time frame: Baseline to Week 12

Change from Baseline in Global Health Status (GHS)/Quality of Life (QoL) Domain as Measured by the GHS/QoL Domain of the EORTC QLQ-C30

The EORTC QLQ-C30 is an 30-item patient-reported questionnaire that measures symptoms and HRQoL. The GHS/QoL Domain is a scale where participants rate items on a 4-point scale (with 1 = 'not at all' to 4 = 'very much'). A change of 5 to 10 points is considered a small change and the lower bound (5) will be used to define the minimum important difference. A change of ≥ 10 to \< 20 points is considered a moderate change.

Time frame: Baseline to Week 12