In the trials, one group of patients received the therapy three times over three weeks, while the other group received the therapy 6 times over 6 weeks. Each group received the same dose of radioactive iodine per week, 40 millicuries (mCi). According to Jackson, this is not tremendously high compared to a thyroid cancer treatment, in which patients receive up to 200 mCi in a single treatment.
As Jackson discovered, the TM-601 that does not bind to cells in the body is rapidly excreted in the urine. "Other tissues will receive some dose," he says, "but the vast majority of the dose is delivered to the cancer cells." To prevent the radioactive compound from being absorbed by the thyroid, which has a voracious appetite for iodine, the patients were given large amounts of non-radioactive iodine prior to the therapy to block the thyroid uptake of I-131.
When the patient returns home several hours after the procedure, there are radiation doses to any family members at home due to the presence of radiation in the patient's body. Such radiation exposures to family members, Jackson found, are low and comparable to those from a family member receiving standard thyroid cancer therapy.
Jackson is encouraged by the safety of this procedure and its potential to help patients with brain gliomas. A recent study of the earlier phase II trials showed that patients receiving up to 40 mCi of weekly dose did not show evidence of any adverse reactions attributable to the radiation. The second-sequence phase II trial at Henry Ford involves 3 patients, with a total of 54 patients across the US currently in investigational trials for the therapy.