Novel Targeted Radiotherapy in Pediatric Patients With Inoperable Relapsed or Refractory HGG

Inclusion Criteria: Previously confirmed (histologically or cytologically) high grade glioma that is clinically or radiographically suspected to be relapsed, refractory, or recurrent for which there are no standard treatment options with curative potential ≥ 2 years of age and ≤ 25 years of age at time of consent/assent If ≥ age 16 years, Karnofsky performance status of ≥ 60. If < age 16 years, Lansky performance status ≥ 60 Platelets ≥ 75,000/μL (last transfusion, if any, must be at least 1 week prior to study registration, and, unless deemed medically necessary, no transfusions are allowed between registration and dosing) Absolute neutrophil count ≥ 750/μL Hemoglobin ≥ 10 g/dL (last transfusion must be at least 1 week prior to study registration, and, unless deemed medically necessary, no transfusions are allowed between registration and dosing) Using the bedside Schwartz formula, estimated GFR (creatinine clearance) > 60 ml/min/1.73m2 Alanine aminotransferase < 3 × ULN Bilirubin < 2 × ULN Patients enrolling at total dose levels > 30 millicurie (mCi)/m2 must have availability or ability to collect an autologous hematopoietic stem cell back-up product prior to CLR 131 administration. At minimum, 2 x 10^6/kg cryopreserved CD34+ cells must be available. Patient or his or her legal representative is judged by the Investigator to have the initiative and means to be compliant with the protocol. Patient or his or her legal representative has the ability to read, understand, and provide written informed consent for the initiation of any study-related procedures. Female patients of childbearing potential must have a negative pregnancy test at screening and within 24 hours of dosing. It is recommended that female caregivers of childbearing potential have a negative pregnancy test within one week of dosing. Patients of childbearing potential must practice an effective method of birth control while participating on this study to avoid possible damage to the fetus. At least 1 measurable lesion with longest diameter of at least 10 mm on any imaging sequence. Patients with previously known neurological deficits must be clinically stable at time of enrollment and able to complete all study related procedures. Patients with documented or newly diagnosed neurological deficits will be enrolled at the investigator's discretion. If patient receives steroids for neurological symptom control, the dose must be stable (unchanged for three weeks prior to screening) or on a steroid tapering regimen. Exclusion Criteria: Antitumor therapy or investigational therapy, within 2 weeks of registration. For certain types of radiation (craniospinal, total abdominal, whole lung [spot irradiation to skull-based metastases is not considered craniospinal radiation for the purposes of this study]), at least 3 months must have elapsed. n.b. Patients participating in non-interventional clinical trials (i.e., non-drug) are allowed to participate in this trial History of hypersensitivity to iodine Any other concomitant serious illness or organ system dysfunction (including cardiac and pulmonary dysfunction) that in the opinion of the Investigator would either compromise patient safety or interfere with the evaluation of the safety of the test drug. Major surgery within 6 weeks of enrollment Known history of human immunodeficiency virus or uncontrolled, serious, active infection Pregnancy or breast-feeding