This clinical trial is focused on studying a type of skin cancer called Stage IIB/C melanoma. The study is investigating the effectiveness of a treatment called nivolumab, which is also known by its code name BMS-936558. Nivolumab is a type of medication that is given through an infusion, which means it is delivered directly into the bloodstream through a vein. The trial compares nivolumab to a placebo to see if it can help prevent the cancer from coming back after it has been completely removed by surgery.

The main goal of the study is to see how well nivolumab works in keeping the cancer from returning. Participants in the study will receive either nivolumab or a placebo after their melanoma has been surgically removed. The study will monitor participants over a period of time to check for any signs of the cancer returning. This will help researchers understand if nivolumab can provide better outcomes compared to not receiving the active treatment.

Throughout the study, participants will undergo regular check-ups and imaging tests, such as CT scans and MRI, to ensure there is no evidence of the disease. The study aims to provide valuable information on whether nivolumab can be an effective treatment option for preventing the recurrence of Stage IIB/C melanoma after surgery. The trial is expected to continue until 2027, allowing researchers to gather comprehensive data on the long-term effects and benefits of the treatment.