This research study is studying a new type of vaccine as a possible treatment for patients with MGMT-unmethylated glioblastoma. This research study is a Phase I clinical trial, which tests the safety of an investigational intervention and also tries to define the appropriate dose of the intervention to use for further studies. "Investigational" means that the intervention is being studied and that research doctors are trying to find more about it. It also means that the FDA (U.S. Food and Drug Administration) has not approved the Personalized NeoAntigen Cancer Vaccine for any use in patients, including people with glioblastoma. The purpose of this study is to determine if it is possible to make and administer safely a vaccine against glioblastoma by using information gained from specific characteristics of the participants tumor. It is known that glioblastomas have mutations (changes in genetic material) that are specific to an individual patient’s tumor. These mutations can cause the tumor cells to produce proteins that appear very different from the body’s own cells. It is possible that these proteins used in a vaccine may induce strong immune responses, which may help the body fight any tumor cells that could cause the glioblastoma to come back in the future.