High-grade glioma is a type of cancerous tumor found in the brain that affects glial cells, which are non-neuronal cells that provide physical and metabolic support to neurons. This study specifically focuses on glial cells that are in the brain. Gliomas make up around 30 percent of all brain tumors and central nervous system tumors, and 80 percent of all malignant brain tumors. This is why it is very important to study treatments for glioma. One very researched treatment is chemotherapy, with a clinical name of Temozolomide (TMZ). Unlike many other drugs, it is able to pass through the blood-brain barrier (BBB), a membrane of cells that blocks potentially harmful substances from the brain. ​​TMZ is an alkylating agent and works by binding to the DNA in tumor cells and disrupting the cell replication process by damaging the DNA, forcing the tumor growth to stop. A more recent development is a treatment called immune checkpoint inhibitors (ICIs) which work by blocking checkpoint proteins from binding to T cells. When natural checkpoint proteins on any of the body’s cells, in this case cancer cells, bind to the corresponding checkpoint protein on T cells, T cells know to turn off, therefore suppressing immune responses. Some cancers have developed these checkpoint proteins to suppress the human immune system. Checkpoint inhibitors work by blocking this interaction, negating the suppressive action, and making the human immune system more productive in its fight against cancer. One specific type of checkpoint inhibitor is called PD-1. Chemotherapy and checkpoint inhibitors have never been combined before to fight against glioma. The idea is that if we combine the two treatments, we can have two productive treatments/fights against glioma — the natural human immune system and chemotherapy. We aim to test this treatment for its effect on the tumor microenvironment (TME) and its efficacy by having different groups: Control, SHAM, TMZ only, ICIs only, and both combined. Mice will be injected and induced with glioma and this process will be repeated 3 times and flow cytometry will be conducted to test for impact on cytokines, Regulatory T cells (Tregs), T cells, and macrophages.