This study tests two medications, **relatlimab** and **nivolumab**, against a standard treatment, **lomustine**, for people with a brain cancer called recurrent glioblastoma. Glioblastoma is a type of cancer that starts in the brain and can come back even after treatment. **Relatlimab** and **nivolumab** are special proteins, known as monoclonal antibodies, which help the body's immune system attack cancer cells. **Lomustine** is a chemotherapy drug that attempts to kill cancer cells by damaging their DNA. **Study Design**: The trial has two groups. One group receives **relatlimab** and **nivolumab** through an IV (a tube in a vein) every 28 days, and the other group takes **lomustine** as a pill every 42 days. Both groups have regular check-ups and tests, like MRIs and blood tests, to monitor the cancer. Key Points: - The study involves regular hospital visits for treatment and tests. - Patients are monitored every 6 months for up to 5 years. - Safety and side effects are carefully tracked for both treatment options.