Personalized NeoAntigen Cancer Vaccine w RT Plus Pembrolizumab for Patients With Newly Diagnosed GBM

This research study is studying a new type of vaccine as a possible treatment for patients with 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 the initial study cohort (Cohort 1) 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. Three additional cohorts (1a, 1b, \& 1c) were added to the study following completion of accrual to the original study cohort (cohort 1). Each new cohort receives NeoVax and radiation therapy as administered to cohort 1 and will also receive pembrolizumab: cohort 1a patients will start pembrolizumab w/in 2 weeks after start of RT, and continue every 3 weeks for up to 2 years; cohort 1b patients will start pembrolizumab 2-4 weeks after completion of NeoVax priming, and continue every 3 weeks for up to 2 years; cohort 1c patients will receive a single dose of pembrolizumab administered within 2 weeks after start of RT, re-start 2-4 weeks after completion of NeoVax priming, and continue every 3 weeks f