Inclusion Criteria:

          -  Provision of formalin-fixed paraffin embedded tissue sample from primary or metastatic
             disease

          -  Karnofsky Performance Score of ≥60.

          -  Additional Inclusion Criteria Specific for Arm A:

               -  Histologically proven diagnosis of GBM. Patients who have had RT for low-grade
                  glioma (LGG) or grade 3 glioma and have subsequently relapsed to histologically
                  confirmed GBM can be considered

               -  A radiological diagnosis of recurrent/relapsed or progressive disease according
                  to RANO criteria.

               -  Completion of first-line radiation at least 6 months prior to study entry.

               -  Patients with tumor-induced seizures must be well controlled on a stable
                  anti-epileptic treatment

               -  Willing to receive anti-epileptic prophylaxis for the duration of study drug
                  administration.

          -  Additional Inclusion Criteria Specific for Arm B:

        **Arm B has now closed to recruitment**

          -  Histologically proven diagnosis of solid tumor malignancy and Magnetic Resonance (MR)
             imaging documenting brain lesions.

          -  Not eligible for Stereotactic Radiosurgery (SRS) treatment of brain tumor.

          -  Patient has not received any previous brain RT to the area that is to be irradiated.
             Prior PBRT may be allowed if there is not significant overlap between the prior and
             new radiation fields.

          -  Non-CNS malignant disease must be sufficiently controlled so that patients can be
             without additional systemic therapy for the required washout period before starting
             therapy until 5 days after the end of RT. Required washout period before starting the
             first dose of AZD1390 (Cycle 1) is 28 days for immune checkpoint inhibitors and 7 days
             for all other agents

          -  Not received radiation to the lung fields within the past 8 weeks.

          -  No history of seizures related to the brain metastases or LMD.

          -  Receiving PBRT (rather than WBRT) during Cycle 1 as standard of care for brain
             metastases

             • Additional Inclusion Criteria Specific for Arm C:

          -  Histologically proven primary diagnosis of GBM with unmethylated O6-methylguanine-DNA
             methyltransferase (MGMT). Grade 4 astrocytoma or histology with molecular features of
             GBM can be considered.

          -  Determination of MGMT promoter status by methylation-specific polymerase chain
             reaction (PCR) or pyrosequencing per local institutional guidelines is required to
             assess eligibility for this Arm.

          -  Patients will have to undergo mutational testing for Isocitrate dehydrogenase 1 (IDH1)
             on a tumor specimen before entering study. Patients are eligible for Arm C regardless
             of their IDH1 mutational status.

          -  No history of uncontrolled seizures after surgery for primary GBM (despite adequate
             antiepileptic therapy) or with need for concurrent administration of more than 2
             antiepileptic drugs.

          -  Willing to receive anti-epileptic prophylaxis for the duration of study drug
             administration

        Exclusion Criteria:

          -  Administration of chemotherapy or any investigational drug in the 28 days or
             carmustine (CCNU) or lomustine (BCNU) in the 6 weeks prior to receiving the first dose
             of treatment in Arms A and C. Administration of checkpoint inhibitors within 28 days
             prior to first dose of treatment and any other agent within 7 days of beginning study
             treatment in Arm B. Hormonal therapies are allowed during study treatment for patients
             in Arm B.

          -  History of severe brain-injury or stroke.

          -  Patient not eligible for sequential MRI evaluations are not eligible for this study.

          -  History of epileptic disorder or any seizure history unrelated to tumor

          -  Treatment with Strong inhibitors or inducers of CYP3A4 within 2 weeks prior to
             receiving study drug

          -  Concurrent therapy with other seizurogenic medications.

          -  Past medical history of interstitial lung disease (ILD), drug-induced ILD, radiation
             pneumonitis which required steroid treatment, or any evidence of clinically active
             ILD.

          -  Concurrent severe and/or uncontrolled medical condition (e.g., severe COPD).

          -  Prior treatment with pneumotoxic drugs, e.g. busulfan, bleomycin, within the past
             year. If prior therapy in lifetime, then excluded if history of pulmonary toxicities
             from administration. Patients who have received treatment with nitrosoureas (e.g.,
             carmustine, lomustine) in the year before study entry without experiencing lung
             toxicity are allowed on study.

          -  History or presence of myopathy or raised creatine kinase (CK) >5 x upper limit of
             normal (ULN) on 2 occasions at screening.

          -  Cardiac dysfunction defined as: Myocardial infarction within six months of study
             entry, NYHA (New York Heart Association) Class II/III/IV heart failure, unstable
             angina, unstable cardiac arrhythmias

          -  Evidence of severe pulmonary infections, as judged by the investigator

          -  With the exception of alopecia, any unresolved toxicities from prior therapy greater
             than National Cancer Institute Common Terminology Criteria for Adverse Events (NCI
             CTCAE 4.03) Grade 1 at the time of starting study treatment and patients with chronic
             Grade 2 unresolved toxicities may be eligible