Making Radioactive Scorpion Venom Safe

At this week's meeting of the Health Physics Society in Providence, researchers will describe how they have helped establish the safety of a surprising new treatment for an aggressive, essentially incurable malignant cancer called high-grade brain glioma, diagnosed in more than 17,000 people in the U.S. every year.

The treatment is based on the discovery that the venom in the Israeli yellow scorpion (Leiurus quinquestriatus) contains a protein that binds selectively to the glioma cells. The procedure uses a compound called TM-601, a synthetic version of the venom protein attached to a radioactive substance called I-131 that kills the glioma cells. When injected into the bloodstream, the radioactive scorpion venom protein travels to the brain and attaches to the glioma cells, with the I-131 releasing radiation that kills the cells.

Describing the second sequence of phase II clinical trials involving human patients, health physicist Alan Jackson (AlanJ@rad.hfh.edu) of the Henry Ford Health System in Detroit will report that he and his colleagues recently established safe procedures for the therapy. Patients in the trial received a radioactive dose of 40 millicuries per week. This dose is not tremendously high compared to a thyroid cancer treatment, in which patients receive up to 200 millicuries of I-131 in a single treatment.

As Jackson determined, patients could safely return home several hours after the treatment, as their families would not be exposed to any more radiation than is typical with a thyroid cancer patient returning home after the procedure. And according to a separate group's study of the first sequence of phase II trials, patients receiving up to 40 millicuries of weekly dose did not show evidence of any adverse reactions attributable to the radiation. The phase II trial at Henry Ford involves 3 patients, with a total of 54 patients across the U.S. currently in investigational trials for the therapy.

Paper WAM-B.11 at the HPS 51^st Annual Meeting, Wednesday, June 28, 2006
Study Demonstrates Safety of Promising Investigational Treatment for Deadly Brain Cancer (press release from TransMolecular, Inc.)