• 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 participants
• Disease that is not amenable to curative surgical and/or locoregional therapies
• No prior systemic treatment for locally advanced or metastatic and/or unresectable HCC
• Measurable disease according to RECIST v1.1
• ECOG Performance Status of 0 or 1 within 7 days prior to randomization
• Child-Pugh Class A within 7 days prior to randomization
• Adequate hematologic and end-organ function
• Female participants of childbearing potential must be willing to avoid pregnancy within 5 months after the final dose of atezolizumab, within 6 months after the final dose of bevacizumab, and within 90 days after the final dose of tiragolumab/placebo
• Male participants with a female partner of childbearing potential or pregnant female partner must remain abstinent or use a condom during the treatment period and for 6 months after the final dose of bevacizumab and for 90 days after the final dose of tiragolumab/placebo to avoid exposing the embryo.
• Pregnancy or breastfeeding within 5 months after the final dose of atezolizumab, within 6 months after the final dose of bevacizumab, and within 90 days after the final dose of tiragolumab/placebo
• 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
• 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
• 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 5 years prior to screening, with the exception of malignancies with a negligible risk of metastasis or death
• Mixed histology or other subtypes/variants of HCC, including, but not limited to, known liver adenocarcinoma, fibrolamellar HCC, sarcomatoid HCC, other rare HCC variant, or mixed cholangiocarcinoma and HCC
• Co-infection with hepatitis B virus (HBV) and hepatitis C virus (HCV)
• Acute Epstein-Barr virus (EBV) infection or known or suspected chronic active EBV infection
• Symptomatic, untreated, or actively progressing central nervous system (CNS) metastases.

The main inclusion criteria include but are not limited to the following:
• Confirmed diagnosis of CLL/SLL and active disease clearly documented to have a need to initiate therapy.
• Has at least 1 marker of disease burden.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 within 7 days before randomization.
• Has the ability to swallow and retain oral medication.
• Participants who are hepatitis B surface antigen (HBsAg) positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks and have undetectable HBV deoxyribonucleic acid (DNA) viral load before randomization.
• Participants with history of hepatitis C virus (HCV) infection are eligible if HCV ribonucleic acid (RNA) viral load is undetectable at screening.
• Participants with human immunodeficiency virus (HIV) who meet ALL eligibility criteria. The main exclusion criteria include but are not limited to the following:
• Has an active hepatitis B virus/ hepatitis C virus (HBV/HCV) infection.
• Has gastrointestinal (GI) dysfunction that may affect drug absorption.
• Has diagnosis of Richter Transformation or active central nervous system (CNS) involvement by CLL/SLL.
• Has had acquired immune deficiency syndrome (AIDS)-defining opportunistic infection in the past 12 months before screening.
• Has clinically significant cardiovascular disease.
• Has hypersensitivity to nemtabrutinib or contraindication to ibrutinib or acalabrutinib, or any of the excipients.
• Has history of severe bleeding disorder.
• Has history of second malignancy, unless potentially curative treatment has been completed with no evidence of malignancy for 2 years.
• Has received any systemic anticancer therapy for CLL/SLL.
• Is currently being treated with p-glycoprotein (P-gp) substrates with a narrow therapeutic index, cytochrome P450 3A (CYP3A) strong or moderate inducers or CYP3A strong inhibitors.
• Received prior radiotherapy within 2 weeks of start of study intervention, or radiation-related toxicities, requiring corticosteroids.
• Received a live or live-attenuated vaccine within 30 days before the first dose of study intervention. Administration of killed vaccines are allowed.
• Has received an investigational agent or has used an investigational device within 4 weeks before study intervention administration.
• Has diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior the first dose of study medication.
• Has active autoimmune disease that has required systemic treatment in the past 2 years. Replacement therapy (eg, thyroxine, insulin, or physiologic corticosteroid) is allowed.
• Has active infection requiring systemic therapy.
• Participants who have not adequately recovered from major surgery or have ongoing surgical complications.