Key Inclusion Criteria:

          1. Histologically confirmed diagnosis of high grade glioma

          2. Evidence of recurrence after treatment (ie, surgery, radiation, or temozolomide) or
             refractory (or intolerant) to treatment

          3. Recovered from toxicity to prior anti-cancer therapy

          4. Adequate bone marrow and organ function

          5. Life expectancy of > 3 months

        Cohort-Specific Inclusion Criteria: In addition to the inclusion criteria listed above, the
        following criteria apply based on enrollment into specific cohorts:

        Phase 1 Dose Escalation Cohorts

          1. Measurable or non-measurable disease

          2. Karnofsky Performance Status (KPS) score ≥ 60

        Phase 2 Expansion Cohort 1

          1. Available tumor tissue

          2. Received prior therapy with radiation or radiation plus temozolomide

          3. Radiographic evidence of progression and measurable disease as determined by the
             Investigator per standard criteria

          4. KPS score ≥ 70

        Phase 2 Expansion Cohort 2

          1. Received prior therapy with radiation or radiation plus temozolomide

          2. Radiographic evidence of progression and measurable disease as determined by the
             Investigator per standard criteria

          3. KPS score ≥ 70

          4. Eligible for surgical resection

        Key Exclusion Criteria:

          1. Have received chemotherapy, radiation, or biological anti-cancer therapy within 14
             days prior to the first dose of IP

          2. Has a history of or current use of bevacizumab as therapy for brain cancer

          3. Received treatment with an investigational agent for any indication within 14 days for
             non-myelosuppressive agent or 21 days (or < 5 half-lives) for myelosuppressive agent
             prior to enrollment

          4. Requires systemic corticosteroid therapy > 4 mg/day (> 2 mg/day for Expansion Cohort
             2) of dexamethasone or equivalent or increasing doses of systemic corticosteroids
             during the 7 days prior to enrollment

          5. Requires anti-seizure medications that are known to be strong inducers of CYP3A4/5
             enzymes (carbamazepine, phenytoin) or has a recent history of uncontrolled or
             intermittent seizures

          6. Females who are pregnant or breast feeding