This clinical trial is focused on studying a type of liver cancer known as Hepatocellular Carcinoma (HCC). The study is investigating the effects of a treatment called Nivolumab, which is also known by its code name BMS-936558. Nivolumab is a medication that is given through an infusion, which means it is delivered directly into the bloodstream through a vein. The trial is comparing Nivolumab to a placebo to see how well it works in preventing the return of cancer in patients who have had surgery or other treatments to remove or destroy their liver tumors.

The purpose of the study is to see if Nivolumab can help patients with HCC who are at high risk of their cancer coming back after they have had surgery or a procedure to remove or destroy the cancer. Participants in the study will receive either Nivolumab or a placebo. The study will monitor the participants over time to see if the cancer returns and to assess their overall health and survival.

Participants will be randomly assigned to receive either the Nivolumab treatment or a placebo. The study will follow them for a period to observe the effects of the treatment. The main goal is to determine if Nivolumab can help keep the cancer from returning and to understand its impact on the participants’ survival. This study is part of a larger effort to find better treatments for liver cancer and improve outcomes for patients at high risk of recurrence.