Additional Study Information: The purpose of this study is to learn more about the safety of a cancer vaccine that teaches the immune system to recognize and possibly destroy tumor cells, and to assess how well the vaccine works. The vaccine has two components. One of them is study drug GRT-C903, and the other is GRT-C904. The vaccine works by stimulating the immune system, which then fights tumors by recognizing and destroying tumor cells. This vaccine will be used in combination with FDA-approved drugs ipilimumab and nivolumab, which are medications that activate the immune system. The overall study treatment, which consists of the vaccine plus the ipilimumab and nivolumab, is not yet approved by the FDA, and is being tested in this study to see if it is safe and if it can help your body control your cancer.