This phase I/Ib trial studies the side effects and best dose of intrathecal nivolumab, and
how well it works in combination with intravenous nivolumab in treating patients with
leptomeningeal disease. Immunotherapy with monoclonal antibodies, such as nivolumab, may help
the body's immune system attack the cancer, and may interfere with the ability of tumor cells
to grow and spread.