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rhenium (186Re) obisbemeda

A precise radiotherapeutic
targeting brain and CNS cancers in adults and children.

What is rhenium (186Re) obisbemeda?

rhenium (186Re) obisbemeda is our lead drug candidate designed for the treatment of recurrent glioblastoma (GBM), leptomeningeal metastases (LM), and pediatric brain cancers (PBCs), such as ependymoma and high-grade glioma.

In preclinical and clinical trials of rhenium (186Re) obisbemeda for treating GBM, ReSPECT-GBM, we delivered up to 20x the absorbed dose of radiation versus standard external beam radiation therapy (EBRT), successfully reducing tumors without significant toxicity. In a preclinical trial of rhenium (186Re) obisbemeda for treating LM, ReSPECT-LM, we administered highly elevated doses of rhenium (186Re) obisbemeda with no maximum tolerable dose reached.

U.S. FDA granted both an Orphan Drug designation and a
Fast Track designation for rhenium (186Re) obisbemeda against glioblastomas, as well as a
Fast Track designation for leptomeningeal metastases.

Our Formulation

An innovative combination
of radiation, small
molecule drug loading
and nanoscale technology.

An innovative combination of radiation, small molecule drug loading and nanoscale technology.

An innovative combination of radiation, small molecule drug loading and nanoscale technology.

Our novel approach involves drug loading using a specially developed small molecule known as BMEDA with the radioisotope, Rhenium-186, and carrying it into the interior of a nanoliposome where it is irreversibly trapped.

Upon administration, Rhenium-186 emits beta energy that precisely targets rapidly dividing cancer cells, sparing the surrounding healthy cells and tissue, as well as gamma energy that allows us to live image the full treatment infusion.

Potential Clinical Benefits

Local Administration

Targeted Delivery

Toxicity Levels

rhenium (186Re) obisbemeda is injected in and near the tumor via a direct infusion using a Convection Enhanced Delivery (CED) catheter or an Ommaya reservoir. Rhenium-186 emits beta energy with a short average tissue penetration length of approximately 2 mm, localizing the attack to the tumor1. The nanoliposome carrier is also nontoxic, degrading naturally in the body.

Elevated Dosing

Treatment Efficacy

Side Effects

In our ReSPECT-GBM clinical trial, rhenium (186Re) obisbemeda was administered at a dose up to 15-20x higher than external beam radiation therapy, destroying cancer more effectively and prolonging survival with fewer side effects.

Improved Retention

Effective Containment

Early Release

When encapsulated in a nanoliposome, Rhenium-186 breaks down slowly such that it destroys tumor tissue more completely than methods where radioisotopes alone are injected directly.

Live Imaging

Tumor Visualization

Dosing Inaccuracies

Rhenium-186 emits gamma energy that allow us to visualize the tumor and drug location, track the rate of drug uptake or clearance in real-time, and potentially adjust the delivery parameters accordingly.

Clinical Targets

Brain Cancer

About Recurrent Glioblastoma (GBM) & Pediatric Brain Cancer (PBC)

GBM (Grade IV astrocytoma) is the deadliest and most common type of brain cancer in adults with no treatment options for significantly extending life. PBC is the second most common type of cancer in children and requires less invasive approaches than those for adult patients.

While radiation is highly toxic to cancer, even at an advanced stage, it is difficult to deliver it past the blood-brain barrier and safely into tumor tissue with precision.

Our Treatment Method

In brain cancer, we use convention enhanced delivery (CED), a local drug delivery technique that when paired with nanoliposomal technology, allows us to bypass the blood-brain barrier and directly infuse rhenium (186Re) obisbemeda into the target region.

Catheter Placement

One or more catheters are placed into the brain and then ‘convected’ directly to the tumor. CED uses a hydraulic pressure gradient to drive flow of rhenium (186Re) obisbemeda into a tissue compartment in, around and through the tumor.

Tumor Penetration & Retention

Nanoliposomes of approximately 100 nanometers, such as those used in rhenium (186Re) obisbemeda, have been shown to convect readily and precisely through tumors in the brain.

Central Nervous System
(CNS) Cancers

About Leptomeningeal Metastases (LM)

LM occurs when cancer spreads to the fluid space of the CNS. There are no good treatments in generally recognized standards of care, with patients often having to choose between toxic treatments and a very short life expectancy.

Treatment of LM with external beam radiation must travel through and therefore harm surrounding normal tissues to get to the tumors. Other radiotherapeutics typically cannot reach and destroy the tumor through systemic administration because of the blood-brain barrier.

Our Treatment Method

We take a highly targeted approach, using an Ommaya ventricular reservoir, to directly administer rhenium (186Re) obisbemeda into the CNS fluid compartment where the tumor is located.

Catheter Implantation

The Ommaya reservoir is a soft, plastic, dome-shaped catheter commonly implanted under the scalp in LM patients, providing direct drug access to the ventricle, beyond the blood-brain barrier.

CSF Infusion

Using the Ommaya reservoir, the drug may be directly injected in the cerebrospinal fluid (CSF), the clear fluid surrounding the brain and spinal cord.