Cancer Therapy with Radioactive Scorpion Venom

BostonBTS writes "Researchers from TransMolecular, Inc. have used chlorotoxin -- a component of giant yellow scorpion venom -- to target radioactive treatments for the deadly brain cancer glioma. From the article: 'In the study, 18 patients first had surgery to remove malignant gliomas, a lethal kind of brain tumor. Then doctors injected their brains with a solution of radioactive iodine and TM-601, the synthetic protein. The solution bound almost exclusively to leftover tumor cells, suggesting that it could be combined with chemotherapy to fight cancer. Furthermore, two study patients were still alive nearly three years after the treatment.' Their paper is slated for publication in the August issue of the Journal of Clinical Oncology."

Comments

Re:Two out of 18...

[DoubleRing]

but what would the expected number of survivors be for a group that wasn't treated with this solution?

RTFA:

Because life expectancy for the 14,000 annual glioma patients in the United States is typically a matter of months, the results shore up animal research indicating that the venom protein may inhibit tumor growth even without a radioactive component, Mamelak said.

Biology Related to Chlorotoxin

[obiwanjabroni]

Howdy,

The effectiveness of chlorotoxin in treatment of glioblastomas was discovered by a scientist here at my institution (http://www.neurobiology.uab.edu/Faculty/Sontheime r/Sontheimer.htm). Glioblastoma is hypothesized to be so deadly because of the ability of cancer cells inside the brain to quickly migrate from the primary site to other sites within the brain, quickly invading normal brain tissue. This makes surgery or radiation not very effective, since migrating cells may be hidden within normal brain that is not irradiated or cut out. The migratory ability of glioblastoma cells is related to its unique ability to change size and morphology to move in between normal brain cells.

The size-changing migratory ability is related to a specific chloride ion channel that expresses highly and uniquely on certain brain cancer cells, including gliomas (PubMed ID: 8804043, 8967454). Chlorotoxin, a chloride channel inhibitor discovered in 1993 (PubMed ID: 8383429) was more interestingly found to bind to this glioma-specific chloride ion channel in mice in 1998 (PubMed ID: 9809993) and humans in 2002 (PubMed ID: 12112367). Although it was shown that chlorotoxin failed to inhibit migratory ability due to size-change, chlorotoxin was shown to inhibit migration by inhibition of another protein involved in breaking down the extracellular matrix, allowing cells to more easily migrate.

The strategy that TransMolecular uses to treat gliomas lies in the specificity of expression of the channel to which chlorotoxin binds. That channel is expressed on the vast majority of glioma tissue samples tested, and only rarely on normal tissue. If one attaches a weak or short-lasting radioactive moiety to chlorotoxin, a potential treatment can be to target glioma cells using chlorotoxin, and then kill them by short-lasting localized radiation. This strategy is already being used in Non Hodgkins Lymphoma and other diseases by attaching to tumor- targeting antibodies a radioactive iodine atom.