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.

This study tests a new drug called PF-08634404 — alone and in combination with other cancer treatments — in people with advanced liver cancer (hepatocellular carcinoma) that cannot be removed by surgery and may have spread. **You may be eligible if...** - You are 18 or older with confirmed advanced liver cancer (HCC) - Your cancer cannot be removed by surgery or local treatment - You have at least one measurable tumor - You have not received any prior systemic (whole-body) therapy for your liver cancer - Your liver function is adequate (Child-Pugh Class A) - Your general health is good (ECOG 0 or 1) **You may NOT be eligible if...** - You have moderate or severe fluid buildup in the abdomen - You have a history of brain confusion caused by liver problems (hepatic encephalopathy) - Your cancer has spread to the brain or spinal cord - You have had another cancer within the past 3 years - You have had an organ or stem cell transplant - You have active autoimmune disease - You have had major surgery or serious heart problems in the past 6 months Talk to your doctor to see if this trial is right for you.