• Posted July 11, 2024

Early Trial Shows New Treatment Hits Tough-to-Treat Glioblastomas Harder

Radioactive substances injected into the body could provide a better way of treating glioblastoma, the most malignant form of brain cancer, a new review says.

The cancer treatment, called targeted alpha therapy (TAT), involves injection of radioactive alpha particles attached to special molecules that seek out cancer cells in the body.

Pre-clinical experiments show that TAT increases survival rates by 16% in newly diagnosed glioblastoma cases, and by 36% in recurrent tumors, researcher reported recently in the journal Targeted Oncology.

TAT is a more powerful and precise approach to radiation therapy than external beam radiotherapy, in which a machine beams targeted gamma rays through the body at a targeted tumor, researchers argue in their paper.

"TAT delivers high amounts of lethal radiation to the tumor at very short range, hitting its target without significantly affecting surrounding healthy tissue,"lead researcher Maram El Sabri, a doctoral candidate with the University of South Australia, said in a news release.

"Alpha particles are up to 10 times more potent when compared to standard photon radiation therapy, killing the cancer cells or at the very least slowing their future growth by damaging their DNA,"she added.

For the evidence review, researchers evaluated results of 34 prior studies related to TAT treatment of glioblastoma. These included lab studies involving cell cultures and mice, as well as a small number of human clinical trials.

Glioblastomas are tough to treat because they quickly grow larger and invade surrounding healthy brain tissue, making it tough to deliver the right dose of radiation needed to kill the tumor.

Standard treatment for glioblastomas currently involves surgery to remove the tumor, followed by external beam radiotherapy and chemotherapy, researchers said.

The best way to use TAT against glioblastoma likely will be injecting the particles directly into the tumor or the brain cavity, researchers said. That will allow the therapy to get past the blood-brain barrier.

Besides its potentially superior effectiveness, TAT also is more cost-effective, senior researcher Eva Bezak, a medical radiation physicist at the University of South Australia, said in a news release.

"Compared to the cost of current immunotherapy or molecular targeting drugs, targeted alpha therapy is relatively cheap,"Bezak said.

Research into TAT for glioblastoma has been hindered by several factors, researcher Frank Saran, an adjunct clinical professor with the University of South Australia, said in a news release.

"First, glioblastoma is a rare cancer so does not affect large swaths of the population,"Saran said. "It also has extremely low survival rates and there is a long-standing history of failed studies in this area. Unfortunately, pharmaceutical companies are often not willing to invest money in GB because it has a low probability of success and is not commercially viable."

As part of her doctoral studies, Maram is developing a computational model to calculate how TAT can be most effectively delivered to the brain after surgery, as well as in combination with conventional radiation therapy and chemotherapy.

"I am excited to find out if we can find the right dosing and radiation range by adding TAT to the conventional treatment options. If this is successful, we might see some significant results in terms of extending a patient's life,"Maram said.

More information

Johns Hopkins Medicine has more about the administration of targeted alpha therapy. 

SOURCE: University of South Australia, news release, July 8, 2024