Radiation Therapy Plus Temozolomide and Pembrolizumab With and Without HSPPC-96 in Newly Diagnosed Glioblastoma (GBM)

Background: * Malignant gliomas are unfortunately, in most cases, a uniformly fatal tumor. Despite aggressive surgery, radiation treatment (RT) and chemotherapy at initial diagnosis these tumors almost always recur. * Many clinical trials in glioblastoma (GBM) have evaluated the addition of agent(s) to standard therapy which consists of concurrent radiation with temozolomide chemotherapy after maximal surgical resection in patients with newly diagnosed disease and salvage chemotherapy with either rechallenge with temozolomide or an alternative alkylating agent such as lomustine (CCNU) or cisplatin. To date, none of the combination strategies have demonstrated clinical benefit. Furthermore, in subjects with an unmethylated MGMT (O6-methylguanine-DNA methyltransferase) promoter temozolomide has only modest benefit and salvage therapies have not demonstrated a significant impact in this subject group underscoring the need for more research. * Immunotherapy offers the promise of improving outcomes for patients with GBM by evoking specific immune responses that may produce a more sustained and less toxic effect than conventional therapy. Heat-shock proteins (HSPs), which function as intracellular chaperones, can be used to deliver a variety of tumor antigens to antigen presenting cells for immune stimulation. * Heat Shock Protein-Peptide Complex-96 (HSPPC-96) consists of the heat shock protein glycoprotein-96 (HSP gp-96) and a wide array of chaperoned proteins, including autologous antigenic peptides (aka vaccine). Heat shock proteins (HSP) are molecules that respond to cellular stress and counteract abnormal protein folding. They are known to modulate immune responses, especially the HSP gp-96. In a stressful environment, such as a tumor, HSPs are upregulated and highly expressed on tumor cells. This protects the tumor and leads to resistance to therapy. HSP expression is associated with cellular proliferation, apoptosis evasion, tissue invasion, metastasis, and angiogenesis. * Pembrolizumab is a potent and highly selective humanized monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/kappa isotype designed to directly block the interaction between Programmed cell death protein 1 (PD-1) and its ligands, programmed death-ligand 1 (PD-L1) and programmed cell death-ligand 2 (PD-L2). Additionally, pembrolizumab is thought to also have activity in the peripherally circulating T-effector cells by reversing lymphocyte exhaustion. It is currently Food and Drug Administration (FDA) approved for use in patients with unresectable or metastatic melanoma and disease progression following ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor and non-small cell lung cancer (NSCLC) with elevated PD-L1 in the tumor. recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy. It is also FDA approved for use with advanced (metastatic) non-small cell lung cancer (NSCLC) whose disease has progressed after other treatments and with tumors that express a protein called PD-L1 and for the treatment of patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) with disease progression on or after platinum-containing chemotherapy. * This study will be the first to evaluate this combination of vaccine (HSPPC-96) and PD-1 inhibition (pembrolizumab) in newly diagnosed GBM patients whose tumors are MGMT promoter unmethylated and are isocytrate dehydrogenase (IDH) wildtype; and will provide important data on immune-modulatory effect of this combination. This may be of particular value in patients with high peripheral PD-L1 expression, but also the value of PD-1 added to standard GBM therapy. As vaccine needs to be generated from the patient s tumor, patients will need to be identified prior to surgery. Eligibility: * MRI findings consistent with a suspected GBM or histologically confirmed newly diagnosed GBM that has not been treated and would benefit from further surgical resection. * Tumor must be supratentorial. * GBM diagnosis must be made by surgical excision (stereotactic biopsy will not be allowed unless there is plan for second surgery to remove greater than or equal to 80% of the tumor) and patients tumors must not have O6-Methylguanine-deoxyribonucleic acid (DNA) Methyltransferase (MGMT) promoter methylation and must be isocitrate Dehydrogenase (IDH) wildtype. * No prior treatment with radiation or chemotherapy for their GBM. * Age greater than or equal to 18 years on day of signing informed consent Objective: \- The primary endpoint is to determine whether the one-year overall survival (OS) rate is improved in newly diagnosed GBM patients whose tumors have an unmethylated MGMT promoter and are IDH wildtype treated with radiation therapy (RT) + temozolomide (TMZ) + Pembrolizumab followed by TMZ + Pembrolizumab + HSPPC-96 vaccine or Placebo vaccine x 6 cycles (1 cycle is 9 weeks). Design: * This will be a randomized, double blind phase II trial of surgery, RT + TMZ + Pembrolizumab followed by TMZ + Pembrolizumab +/- HSPPC-96 in newly diagnosed GBM patients whose tumors have an unmethylated MGMT promoter and are IDH wildtype. * Subjects will be assigned to intervention based on ability to generate vaccine as follows: * If \>= 80 % of tumor removed, \>=7 g of tumor is resected but HSPPC-96 cannot be generated, subjects will be treated on the ancillary arm of RT+TMZ +Pembrolizumab followed by TMZ+ Pembrolizumab. * If\>= 80% of contrasting enhanced tumor removed (based on T1 Post contrast magnetic resonance imaging (MRI) using cross sectional measurement), \>= 7 g of tumor is resected and sufficient HSPPC-96 is generated, subjects will be included in the main cohort and will be randomized on a 1:1 basis to receive: * RT+TMZ +Pembrolizumab followed by TMZ+Pembrolizumab + Placebo OR \--- RT+TMZ +Pembrolizumab followed by TMZ+Pembrolizumab+HSPPC-96 -Subjects whose tumor does not meet the criteria (unmethylated MGMT promoter and IDH wildtype by pathology) and for whom \< 80 % of tumor is removed or \< 7g of tumor is resected are not eligible for further intervention. Approximately 8 potentially eligible patients are screened per month, and it is anticipated that at least 1-2 per month will be accrued per site.