Last updated on May 2018

Maximum Tolerated Dose Safety and Efficacy of Rhenium Nanoliposomes in Recurrent Glioblastoma

Brief description of study

While radiation is an essential component to the treatment of glioblastoma, it's use is limited due to toxicity when higher doses are attempted. Rhenium is a compund which releases radiation in small particles that are absorbed after only a fraction of an inch. This limited penetration means that high doses potentially can be given without the toxicity of other forms of radiation. In order for the radiaiton to be retained within the tumor, it has been packaged in microscopic fat like particles termed nanoliposomes. These facilitate the uptake of the radiation particles by the tumor. In order to better characterize this form of radiation therapy, it is being administered in patients who have failed other forms of therapy for glioblastoma. The treatment is administered by tubing inserted into the center of the tumor in the operating room. There are two portionms to this study. The first involves progressively increasing doses until the most tolerable dose can be identified. The second portion of the study involves a larger number of patients being treated at the determined most tolerable dose to better evalaute how well the treatment works.

Detailed Study Description

Rhenium-186 (186Re) (half-life 90 hours) is a reactor produced isotope with great potential for medical therapy. It is in the same chemical family as Technetium-99m (99mTc), a radioactive tracer that is the most commonly used isotope for diagnostic scintigraphic imaging in nuclear medicine. Like 99mTc, rhenium is not taken up by bone and is readily cleared by the kidneys. 186Re emits both therapeutic beta particles and every 10 isotope decays is associated with a gamma photon. The average 186Re beta particle path length in tissue of 2mm is ideal for treatment of solid tumors. Additionally, the emitted gamma photons have similar photon energy to those emitted by 99mTc, therefore allowing for imaging of the isotope within the body on standard nuclear imaging machines available in routine medical practice. Therefore, the 186Re isotope has great potential in CED applications of local therapy of solid tumors. However, a carrier is needed to deliver the isotope to the brain and maintain its localization at the desired site, as otherwise it would quickly disperse and be carried away from the site of injection by the circulatory system.

Liposomes are spontaneously forming lipid nanoparticles that have been well studied for over 30 years. Although larger liposomes can be manufactured, the most useful size range for drug carrier applications is 80-100 nm. Liposomes of this size are often referred to as nanoliposomes and have the ability to facilitate retention at the site of injection. A method for the efficient loading of liposomes with the to very high levels of specific activity has been developed. These rhenium-labeled nanoliposomes (186RNL) have shown great promise in preclinical studies 186RNL of glioblastoma that surpassed results typically seen with currently standard treatment modalities such as oral temozolomide or intravenous bevacizumab.

This is a single center, sequential cohort, open-label, dose-escalation study of the safety, tolerability, and distribution of 186RNL given by convection enhanced delivery to patients with recurrent or progressive malignant glioma after standard surgical, radiation, and/or chemotherapy treatment.

Clinical Study Identifier: NCT01906385

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Andrew J Brenner, M.D., Ph.D.

The Cancer Therapy and Research Center at UTHSCSA
San Antonio, TX United States
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