MCT for the Harvard/UCSF ROBIN Center

Inclusion Criteria: * Enrollment on one of the following clinical trials: * Pacific Pediatric Neuro-Oncology Consortium PNOC023: Open label Phase 1 and Target Validation study of ONC206 in Children and Young Adults with Newly Diagnosed or Recurrent Diffuse Midline Glioma (DMG), and Other Recurrent Primary Malignant Brain Tumors (NCT04732065) - Arm A or B (Key Eligibility Criteria: Newly diagnosed DMG, Age ≥ 2 years, If on corticosteroids, on a stable or decreasing dose for ≥ 3 days prior to baseline MRI scan, Karnofsky ≥ 50 for age \>16 or Lansky ≥ 50 for age ≤ 16, No known disorder that affects the immune system or uncontrolled infection) * Children's Oncology Group ANBL1531: A Phase 3 Study of 131I-Metaiodobenzylguanidine (131I-MIBG) or Crizotinib Added to Intensive Therapy for Children with Newly Diagnosed High-Risk Neuroblastoma (NCT03126916) - Arm B (Key Eligibility Criteria: Diagnosis of high-risk neuroblastoma (INRG Stage M with MYCN amplification or age \> 547 days, INRG Stage MS with MYCN amplification, INRG Stage L2 with MYCN amplification, or progression to Stage M in certain groups), Age ≥ 1 and ≤ 30 years at diagnosis, No prior systemic or radiation therapy, with certain exceptions, No contraindication to targeted radiopharmaceutical therapy) * Tumor tissue confirmation of malignancy * Adequate bone marrow, renal, liver and neurologic function * Availability of tumor tissue, blood and/or CSF biospecimens Exclusion Criteria: * Pregnancy or breastfeeding * Inability to follow the procedures of the study