If you choose to join this study, you will go through a study screening period that lasts about 14 days and includes:

• Physical exams
• Blood draws and a urine sample
• An Imaging scan (MRI)
• A lumbar puncture (spinal tap)
• An electrocardiogram (ECG) and echocardiogram (ECHO)

If you are eligible to join the study based on your screening results, you will proceed to the study regimen phase. The procedures during this phase will depend on the routine care that your study doctor believes is appropriate. The study regimen phase has 3 parts, and you may be eligible to participate in some or all of the parts. If your doctor believes that you should have surgery to resect your tumor, you will participate in Part 1 of the study regimen. In this part, you will get 2 doses of the study drug before your tumor is resected. If your doctor believes that radiation therapy is appropriate for you, you will participate in Part 2 of the study regimen. In this part, you will take the study drug at the same time you get radiation therapy. Everyone who joins the study will participate in Part 3. During this part, you will take the study drug in combination with paxalisib. Both the study drug and paxalisib are pills that you take by mouth. In addition to the drug regimen and surgery and/or radiation (if applicable), participation in the study will also involve:

• Physical exams
• Blood draws
• Stool samples
• Imaging scans (MRI)
• Heart scans (ECG)
• Questionnaires

You will stay on the study regimen until you and your doctor decide that it is not beneficial for you to continue. About 14 days after you stop the study regimen, we will schedule you to come to the clinic for an end-of-study visit. About 30 days after you finish the study regimen, someone from the study team will contact you to see how you are doing and ask about any medicines you are taking and if you are having any side effects. About every 3 months after you finish the study, someone from the study team will contact you to see how you are doing and ask you to complete a questionnaire.