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

Inclusion Criteria:

• Previously confirmed (histologically or cytologically) high grade glioma that isclinically or radiographically suspected to be relapsed, refractory, or recurrent

• ≥ 10 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, Lanskyperformance status ≥ 60

• Platelets ≥ 75,000/μL (last transfusion, if any, must be at least 1 week prior tostudy registration, and, unless deemed medically necessary, no transfusions areallowed between registration and dosing)

• Absolute neutrophil count ≥ 750/μL

• Hemoglobin ≥ 8 g/dL (last transfusion must be at least 1 week prior to studyregistration, and, unless deemed medically necessary, no transfusions are allowedbetween registration and dosing)

• Using the bedside Schwartz formula, estimated GFR (creatinine clearance) > 60ml/min/1.73m2

• Alanine aminotransferase < 3 × ULN

• Bilirubin < 2 × ULN

• At least 1 measurable intracranial lesion with longest diameter of at least 10 mm onany imaging sequence.

• Patients with previously known neurological deficits must be clinically stable attime of enrollment and able to complete all study related procedures. Patients withdocumented or newly diagnosed neurological deficits will be enrolled at theinvestigator's discretion.

• If patient receives steroids for neurological symptom control, the dose must bestable (unchanged for three weeks prior to registration) or on a steroid taperingregimen. Initiation of steroids per routine care immediately prior to CLR 131 dosingis acceptable

• Patient or his or her legal representative is judged by the Investigator to have theinitiative and means to be compliant with the protocol.

• Patient or his or her legal representative has the ability to read, understand, andprovide written informed consent for the initiation of any study-related procedures.

• Female patients of childbearing potential must have a negative pregnancy test atscreening and within 24 hours of dosing. It is recommended that female caregivers ofchildbearing potential have a negative pregnancy test within one week of dosing.

• Patients of childbearing potential must practice an effective method of birthcontrol while participating on this study to avoid possible harm to the fetus.

Exclusion Criteria:

• Antitumor therapy or investigational therapy, within 3-half-lives of the agentpreceding the present study. For certain types of radiation (craniospinal, totalabdominal, whole lung [spot irradiation to skull-based metastases is not consideredcraniospinal radiation for the purposes of this study]), at least 3 months must haveelapsed. Palliative focal radiation to non-target lesions should be completed atleast 2 weeks prior to dosing. Patients participating in non-interventional clinicaltrials (i.e., non-drug) are allowed to participate in this trial

• History of hypersensitivity to thyroid protection medication (e.g., potassiumiodide, Lugol's solution, etc.)

• Any other concomitant serious illness or organ system dysfunction (including cardiacand pulmonary dysfunction) that in the opinion of the Investigator would eithercompromise patient safety or interfere with the evaluation of the safety of the testdrug.

• Major surgery within 6 weeks of enrollment unless delay in therapy posesunacceptable risk to the patient due to clinical progression (enrollment o suchpatients should be discussed with Medical Monitor)

• Known history of human immunodeficiency virus or uncontrolled, serious, activeinfection

• Pregnancy or breast-feeding