Purpose

This is an open-label, exploratory study to evaluate nivolumab with or without ipilimumab based on percentage of tumoral CD8 cells at the time of treatment in participants with varying advanced solid tumors. Participants who have a tumor with ≥ 15% CD8 cells (classified as CD8 high) will receive nivolumab monotherapy, and participants who have a tumor with \< 15% CD8 cells (classified as CD8 low) will receive ipilimumab in combination with nivolumab.