Phase 1/1b Study to Evaluate Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of AMG 596 as Monotherapy and in Combination With AMG 404 in Subjects With Glioblastoma or Malignant Glioma Expressing Mutant Epidermal Growth Factor Receptor Variant III (EGFRvIII)

Number of Participants With Dose-Limiting Toxicities (DLTs)

Time Frame: Up to 28 days

A DLT was any of the following occurring and regarded by the investigator as related to AMG 596. Hematological DLTs: absolute neutrophil count (ANC) \<0.5×10\^9/L for ≥7 days, febrile neutropenia with ANC\<0.5×10\^9/L and fever ≥38.5°C, platelets\<50×10\^9/L\>7 days or clinically significant bleeding. Non-hematological DLTs: any grade 4 non-hematological toxicity, any grade ≥3 non-hematological toxicity if nausea and vomiting, grade 3 non-hematologic toxicity lasting \>3 days despite treatment, grade 3 fatigue wasn't classified as DLT, grade 3 acute kidney injury, grade 3 seizure, ataxia, encephalopathy, other grade 3 neurologic-related adverse events lasting \>3 days despite treatment, neurologic-related adverse event leading to treatment interruption needing\>1 week to resolve to grade≤1, any grade 3 endocrinopathy that can't be controlled by hormonal replacement. Toxicity grading was graded using the Common Terminology Criteria for Adverse Events (CTCAE v4.0)

Number of Participants With Treatment Emergent Adverse Events (TEAEs)

Time Frame: First dose of study drug until 37 days after last dose or end of study, whichever is earlier. Duration with median (min, max) in months: 3.32 (1.28, 29.31)

An adverse event (AE) was defined as any untoward medical occurrence in a clinical trial participant. A TEAE was any AE that begun or worsened after the initial dose of investigational product. Any clinically significant changes in vital signs, physical examinations, and clinical laboratory tests that begun or worsened after the initial dose of investigational product were recorded as TEAEs.

Number of Participants With Treatment-Related Adverse Events (AEs)

Time Frame: First dose of study drug until 37 days after last dose or end of study, whichever is earlier. Duration with median (min, max) in months: 3.32 (1.28, 29.31)

A treatment-related AE was defined as any untoward medical occurrence in a clinical trial participant that was considered related to the investigational product. Any clinically significant changes in vital signs, physical examinations, and clinical laboratory tests that were considered related to the investigational product were recorded as treatment-related AEs.