Association of Peripheral Blood Immunologic Response to Therapeutic Response to Adjuvant Treatment With Immune Checkpoint Inhibition (ICI) in Patients With Newly Diagnosed Glioblastoma or Gliosarcoma

Background: Glioblastoma (GBM) is a type of malignant glioma. These cancers are nearly always fatal. People who develop these cancers get aggressive treatments. But the tumors almost always recur. Researchers want to study people with newly diagnosed disease to learn more. Objective: To study people with newly diagnosed GBM or gliosarcoma to look at the changes in immune cells in the blood of those who take ipilimumab and nivolumab, along with temozolomide. Eligibility: Adults ages 18 and older with newly diagnosed GBM or gliosarcoma, who have had surgical removal of their tumor and have completed standard initial chemotherapy and radiation therapy. Design: Participants will be screened with the following: Medical record review Medical history Physical exam Tests to assess their nervous system and their ability to do typical activities Blood tests Tumor assessment. For this, they will have magnetic resonance imaging (MRI). They may get a contrast dye through an intravenous (IV) catheter. The MRI scanner makes noise. They will get earplugs. Electrocardiogram. It measures heart rate and rhythm. They will lie still. Sticky pads will be placed on their chest, arms, and legs. Screening tests will be repeated during the study. Treatment will be given in cycles. Each cycle lasts 4 weeks. Participants will get nivolumab and ipilimumab via IV. They will take temozolomide by mouth. They will keep a pill diary. Participants will fill out surveys about their symptoms. Participants will have follow-up visits about 60 days and 100 days after treatment ends. Then they will be contacted every 6 months for the rest of their life.