Symbiotic-GI-13: A Study to Learn About Study Medicine Called PF-08634404 as a Single Treatment and Combination Treatment in Adult Participants With a Liver Cancer Called Hepatocellular Carcinoma, That is Too Advanced to be Removed by Surgery and May Have Spread to Other Parts of the Body.

Open to people ages 18 years and up

• 18 years of age or older at screening.
• Locally advanced or metastatic HCC with diagnosis confirmed by histology/cytology or clinically by AASLD criteria (for patients with cirrhosis). Participants without cirrhosis require histological confirmation of diagnosis.
• Disease that is not amenable to curative surgical and/or locoregional therapies, or progressive disease after surgical and/or locoregional therapies.
• At least 1 measurable (as defined by RECIST 1.1 per investigator) and untreated lesion.
• Adequate hepatic, liver, and renal function
• No prior systemic therapy for HCC.
• ECOG performance status 0 or 1
• Child-Pugh Class A

• Moderate or severe ascites.
• History of hepatic encephalopathy.
• Participants with known active CNS lesions, including leptomeningeal metastasis, brainstem, meningeal, or spinal cord metastases or compression.
• Clinically significant risk of hemorrhage or fistula.
• Participants with any history of another malignancy within 3 years.
• History of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation.
• Participants with active autoimmune diseases requiring systemic treatment within the past 2 years.
• Clinically significant cardiovascular disease within 6 months prior to the first dose.
• Major surgery or severe trauma within 4 weeks prior to the first dose or planned major surgery during the study.
• History of severe bleeding tendency or coagulation dysfunction.
• History of severe ulcers, unhealed wounds, gastrointestinal perforation, abdominal fistula, gastrointestinal obstruction, intra-abdominal abscess, or acute gastrointestinal bleeding, including bleeding event due to esophageal and/or gastric varices, within 6 months prior to the first dose.
• Participants with acute, chronic or symptomatic infections.
• Participants with history of immunodeficiency.