Novel Targeted Radiotherapy in Pediatric Patients with Inoperable Relapsed or Refractory High-Grade Glioma

Trial Summary

  • Phase 1b – Dose Finding Study

  • High-Grade Glioma (HGG)

  • Investigational CLR 131 (iopofosine I 131)

  • 10 - 25 years old

    Children, adolescents, and young adults

  • 50

  • Oct 2023 –  Sept 2026 (estimated)

  • Active participation in the trial could last approximately 6 months with routine follow-up for one year after, followed by yearly check-ins

Are there any therapeutic alternatives?

You do not have to participate in this study to receive treatment for your cancer. Alternatives to participating in this study include the use of other forms of therapy or experimental programs to treat your cancer, or no treatment for your cancer and providing care to make you as comfortable as possible during the course of your disease. You should talk to your doctor about each of these choices before you decide if you will take part in this study. The study researchers can also discuss your alternatives with you.

Why is this trial being done?

The primary purpose of this study is to determine the dose of CLR 131 (iopofosine I 131)  that can safely be given. We also want to learn about the side effects and problems that the drug can cause. We will also study the effect of the drug on your cancer. CLR 131 (iopofosine I 131) is an
investigational radioactive drug. The word "investigational” means that CLR 131 is not approved by the U.S. Food and Drug Administration (FDA) and is available for research use only.


Radiotherapy has been used as a cancer therapy for more than 40 years. The goal of targeted radiotherapy is selective delivery (directed to tumor) of effective doses of radioactive isotopes (amount of radiation) that destroy tumor tissue. It also limits the effect on surrounding normal tissue. Although there may be some accumulation in normal tissues, these tissues have not shown clinical signs of damage in patients to date.


In experiments with animals and on cell tissue, CLR 131 has been shown to slow tumor growth. This compound appears to target cells with cancer rather than cells without cancer. CLR 131 (iopofosine I 131) works by delivering radiation (iodine-131) directly to cancer cells. CLR 131 (iopofosine I 131) is taken up by the cells and then the radiation is delivered inside. The radiation
damages the genes in cancer cells. As mentioned above, this study is being done to learn more about the safety of a new investigational drug, CLR 131 (iopofosine I 131).

Participation Criteria

Clinical trials have qualifying conditions that someone must meet in order to participate. Listed to the right are the key inclusion and exclusion criteria for this trial.

    • You must have a diagnosis of High-Grade Glioma that is suspected to be relapsed, refractory or recurrent, meaning the tumor is coming back or not responding to treatment. Patients with ependymoma may enroll with approval from the Sponsor of the trial. 

    • You must be age 10-25 years old at the time of consent for the trial. 

    • You must have at least 1 measurable intracranial lesion of at least 10mm. 

    • Your doctor will evaluate your performance status and labs to determine if you are eligible for this study.  

    • If you have neurologic symptoms, they must be stable for at least 1 week and you must be able to complete all study-related procedures. If you have new neurologic symptoms, you may be enrolled if your doctor feels it is appropriate.  

    • If you are taking steroids for neurologic symptoms, the dose of steroids must be the same for at least 1 week before you enroll on this study, or you must be on a steroid taper regimen. 

    • You and your guardian must be able to complete all required study-related activities. 

    • If you are a female of childbearing potential, you must have a negative pregnancy test at the time of screening and within 24 hours of receiving the study medication.  

    • If you are sexually active, you must use an effective method of birth control while participating in the study.  

    • You may not participate in this trial if you have received anti-cancer therapy within a certain amount of time, depending on the therapy that was used. Your doctor will be able to determine this timeframe.   

    • You may not participate in this trial if you have an allergy to thyroid protection medication. 

    • You may not participate in this trial if you have another serious illness that your doctor feels would compromise your safety or interfere with evaluations on this trial. 

    • You may not participate in this study if you have had major surgery within 6 weeks of enrollment. You may be enrolled with the approval of the Sponsor if delaying treatment would pose unacceptable risk of disease progression. 

    • You may not enroll if you have a history of HIV, or if you have an uncontrolled, serious, or active infection.