This study is for patients that have been diagnosed with relapsed/refractory neuroblastoma. The investigational drug given is eflornithine (DFMO) along with etoposide. DFMO is the investigational drug being used along with etoposide for treatment of neuroblastoma. Participants will undergo a number of standard tests and research-related procedures before being able to enroll in this study. Some risks include but are not limited to: fewer red and white blood cells, diarrhea, abdominal pain, loss of appetite, skin rash, seizure, difficulty swallowing and blurred vision. Participants can expect to be on this study for approximately 2 years. Participants will then be followed for up to 5 years after study completion.

This study is for patients with brain cancer. The study is being done to see if giving radiation before surgery will improve the length of time without the cancer returning, worsening or causing scarring in the brain.

This study is for men or women who received stereotactic radiosurgery to treat cancer that spread to their brain, and now the cancer has returned in other areas of the brain. This study is being done to see if by adding radiation therapy called whole-brain radiation therapy that avoids the hippocampus to preserver memory plus medication approved to treat dementia can extend these patients lives.

This study is for newly diagnosed previously untreated neurofibromatosis type 1 (NF1) associated with low-grade glioma (LGG). The purpose of this study is to see if selumetinib works just as well as the standard treatment of carboplatin/vincristine (CV) for subjects with NF1-associated LGG, and to see if selumetinib is better than CV in improving vision in subjects with LGG of the optic pathway. Participants can expect to receive treatment for up to 24 months, until the cancer gets worse or until the side effects are too great. After study completion, participants will continue to be followed for up to 10 years.

This study is for newly diagnosed or previously untreated low-grade glioma (LGG). The overall goal of this study is to see if selumetinib works just as well as the standard treatment using carboplatin and vincristine (called CV) for subjects with LGG. Selumetinib is a drug that works by blocking a protein (a basic building block of the human body) that lets cancer cells grow without stopping. Participants can expect to receive treatment on this study for about 1–2 years. After study completion, participants will continue to be followed for up to 10 years.

This study is for participants that have been diagnosed with Medulloblastoma. The purpose of this study is to test the effectiveness of using an investigational agent called DFMO for Medulloblastoma. An investigational drug is one that has not been approved by the U.S. Food and Drug Administration (FDA). This study will look at the ability of this study drug to either keep participants tumor in remission or if they have active tumor, for their tumor to respond to the treatment and will also look at the safety and tolerability of DFMO. After this first day participants will be seen in clinic once every 30 days for the first 6 months of the study, after that they will be seen once every 90 days for the remainder of the study. These visits will last about 2 hours.

This study is for patients with rare Central Nervous (brain or spine) tumors. The purpose of this study is to determine whether the experimental drug, nivolumab can shrink tumors in patients with rare Central Nervous System (brain or spine) tumors or increase the time it takes for these tumors to grow or spread throughout the body.

This study is for participants that have been diagnosed with a high-risk neuroblastoma that cannot be treated or did not improve with existing therapies, or the cancer came back after treatment with existing therapies. This study involves investigational drugs called 64Cu-SARTATE and 67Cu-SARTATE. The investigational drugs will be given as an IV injection. The study is divided into 2 parts: The Dose Escalation Phase and the Cohort Expansion Phase. The phase that participants will enroll to will depend on when they enter the study. The age range for participants is from 12 months to 25 years. Participants can expect to be in this study for approximately 14 months. Then followed by remote or virtual visits every 6 months for up to 36 months (3 years) after the initial dose of study therapy drug 67Cu-SARTATE.