CSU Researchers Discover Drug Delivery Technique that Limits Toxic Side Effects for Animal Cancer Patient
Colorado State University researchers have developed a way to deliver intravenous radiation drugs to bone cancer patients without causing damage to other healthy cells and vital organs, drastically reducing illness and other common side effects of toxic radiation treatments. The technique also allows doctors to deliver radiation in only one dose - as opposed to the standard of three to six - and in a higher, more effective concentration.
By isolating and separating circulating blood to the area of the tumor through a heart lung machine while delivering radioactive drugs, doctors at the University's Flint Animal Cancer Center deliver higher radiation doses to only the tumor while protecting vital organs and healthy tissues. The doctors are working to pinpoint a dose that will achieve 90 percent or higher tumor kill rates in their canine patients; the goal for traditional treatments in people also is 90 percent tumor die-off before surgery.
The study uses a radiation drug called samarium that is mixed with a special substance that causes the radioactive drug to bind to mineral in bones. The sticky substance allows the radiation to release into bones. It is more attracted to bone tumors than to healthy bone because tumors make bone at a more active rate than healthy bones. However, the substance also sticks to healthy bone, causing damage to bone marrow in healthy areas of the body as well as in the bone tumor. Children who currently receive samarium treatment to their entire body often must have bone marrow transplants because of the extensive damage the radiation does to healthy bone marrow.
"The results of this study could change the standard of care for bone cancer patients – both humans and dogs," said Dr. Nicole Ehrhart, a veterinarian and cancer expert at Colorado State. "While most osteosarcoma patients don't receive radiation treatment, we believe that, when delivered with this method that allows doctors to isolate the dose to the tumor, radiation treatment is very effective. In dogs, we know that using radiation in combination with chemotherapy increases our success over just one or the other treatments used alone."
Dr. Ehrhart points out that the technique may also allow other drugs to be used for bone tumor treatment that may typically have been avoided because of their toxicity when applied to the entire body.
At the Animal Cancer Center, Dr. Ehrhart and other researchers have isolated the blood supply to a limb using special catheters and tourniquets, and circulated blood from that limb through a heart lung machine. The radiation drug is delivered into the isolated blood supply, saving the healthy bone marrow in the rest of the patient's body from exposure to radiation. Once the radiation drugs reach the tumor, it is flushed from the system and the heart lung machine is removed, allowing normal blood flow to return.
Results of the study show that because the technique allows higher doses of radiation directly to tumors. The dogs, patients at the Animal Cancer Center, participate in the study with their owner's consent and have few side effects. Early results show that the tumor die-off is significant. The study is funded by M.D. Anderson Cancer Center, the Limb Preservation Foundation in Denver and the Animal Cancer Center.