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:
• • 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 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