A Phase 2b Clinical Study With a Combination Immunotherapy in Newly Diagnosed Patients With Glioblastoma

Key Inclusion Criteria: * Has a Karnofsky performance scale (KPS) score ≥ 70 at screening * Has a new diagnosis of GBM (WHO GRADE III or Grade IV GBM) based on the treating neurosurgeon's best clinical judgement * Has a diagnostic contrast-enhanced magnetic resonance imaging (MRI) scan with fluid attenuated inversion-recovery (FLAIR) sequence of the brain at screening. Participants must have a confirmed measurable disease pre-operatively with at least 1 lesion measuring a total bi-perpendicular product of 4 centimeter square (cm\^2) in 2 different planes (axial, sagittal, or coronal) * The tumor must be located in the supratentorial compartment * Has adequate bone marrow and organ function at screening Key Exclusion Criteria: * Has bi-hemispheric disease, multicentric disease, or disease burden involving the brain stem or cerebellum based on MRI post-gadolinium enhancement * Has received any previous surgical resection or any anticancer intervention for glioma * Has any history of glioma, a concurrent malignancy, or malignancy within 3 years of randomization, unless definitive therapy is completed, with the exception of basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix or breast that has completed curative therapy * Has any severe immunocompromised condition (eg, human immunodeficiency virus (HIV) with a cluster of differentiation \[CD\] 4+ cell count \<200\*10\^6/liter \[L\]) or any active uncontrolled autoimmune disease (eg, Crohn's disease) * Has an active cardiac disease or a history of cardiac dysfunction * Is receiving any other investigational agent(s) or has received an investigational agent within 30 days or 5 half-lives of investigational agent use, whichever is longer, prior to screening * Is partaking in another interventional study. Participants who are partaking in an observational study are eligible * Has received a live vaccine within 30 days of screening * Has active and uncontrolled/untreated hepatitis B virus (HBV), hepatitis C virus (HCV), HIV, or any other active infections that, in the Investigator's opinion, would impair or prohibit a participant's participation in this study. * Is receiving treatment with Tumor Treating Fields or Optune®