Inclusion Criteria:

          -  Has a diagnosis of locally advanced or metastatic solid tumor

          -  Is of age ≥ 18 years

          -  Has a life expectancy of ≥ 6 months

          -  Has adequate organ function

          -  If a female patient, must not be pregnant or breastfeeding and not a woman of
             childbearing potential (WOCBP) OR a WOCBP who uses contraception or is abstinent from
             heterosexual intercourse during the study and for a minimum of 30 days after the last
             study drug administration, or if a male patient, must be abstinent from heterosexual
             intercourse OR agree to use contraception

          -  Able to swallow oral medications

        Additional Inclusion Criteria for GBM cohort

          -  Must have histologically confirmed glioblastoma, IDH-wild type that is first recurrent
             following radiation therapy and temozolomide according to the Response Assessment in
             Neuro-Oncology (RANO) criteria

          -  Must have archival tumor tissue available from a previous surgery for glioblastoma

          -  Must have measurable (defined as at least 1 cm x 1 cm) contrast-enhancing lesion by
             MRI imaging within 21 days of starting treatment

          -  Must be able to undergo MRI of the brain with gadolinium. Patients must be maintained
             on a stable or decreasing dose of corticosteroid regimen (no increase for 5 days)
             prior to this baseline MRI

          -  Must have recovered from prior therapy to grade ≤1 severity (except for alopecia and
             lymphocytopenia) National Cancer Institute Common Terminology Criteria for Adverse
             Events (NCI-CTCAE)

        Exclusion Criteria:

          -  Has a history of untreated brain metastasis or history of leptomeningeal disease or
             spinal cord compression

          -  Has failed to recover from the reversible effects of prior anticancer therapy (does
             not apply to GBM cohort)

          -  Has uncontrolled or poorly controlled hypertension

          -  Has malabsorption due to prior gastrointestinal (GI) surgery or GI disease

          -  Has had any major cardiovascular event within 6 months prior to study drug
             administration

          -  Has any other clinically significant cardiac, respiratory, or other medical or
             psychiatric condition that might interfere with participation in the trial or
             interfere with the interpretation of trial results

          -  Has had major surgery within 4 weeks before first study drug administration

          -  Has known HIV

          -  Has an active infection requiring systemic treatment

          -  Is participating in another therapeutic clinical trial

        Additional Excusion Criteria for GBM cohort:

          -  Has received prior anti-VEGF therapy including bevacizumab (i.e. patients must be
             bevacizumab naïve)

          -  Is receiving enzyme-inducing anti-epileptic drugs (EIAED). Patients may be on
             non-enzyme inducing anti-epileptic drugs or not be taking any anti-epileptic drugs.
             Patients previously treated with EIAED may be enrolled if they have been off the EIAED
             for 10 days or more prior to the first dose of belzutifan