Through a licensing agreement, Martin Marietta Energy Systems has granted exclusive rights to Isotope Products Laboratories, Inc. (IPL), Burbank, Calif., to manufacture and market the rhenium-188 generator. The device was developed by F. F (Russ) Knapp and colleagues in the Nuclear Medicine Group of the Health Sciences Research Division at the Department of Energy's (DOE's) Oak Ridge National Laboratory (ORNL). ORNL is managed by Martin Marietta for DOE.
IPL, founded in 1967, produces radioisotopes used in environmental measurements, analytical instruments, and nuclear medicine. IPL's new nuclear medicine subsidiary, IPL Imaging and Therapeutics, will manufacture the generator and seek U.S. Food and Drug Administration approval to market it to hospitals.
"We hope to build upon the solid development work of Dr. Knapp's group," Len Hendrickson, IPL president, said. "Much clinical development work remains before the rhenium generator can bring benefits to patients worldwide. We look forward to completing the work necessary to bring the product to market. The rhenium generator is an important addition to Isotope Products' growing line of nuclear medicine products."
The source of the tungsten-188 for the generator is ORNL's High Flux Isotope Reactor. As the radioactive tungsten decays in the generator, it decays into radioactive rhenium-188, which can be used for medical treatment.
"Because half of tungsten-188's radioactivity disappears in 69 days," Knapp said, "the shelf life of the generator is at least two months. Rhenium is constantly being supplied for several weeks. The radioactive rhenium produces short bursts of light called photons as half of its radioactivity decays in about 17 hours.
"After injection into the patient," he added, "the distribution in the body of rhenium-188-labeled agents can be monitored with photon-sensitive cameras. More importantly, the radiation released by the rhenium can penetrate a third of an inch into tumor tissue, for example, suggesting that it can be used to treat large tumors."
The rhenium can be chemically attached to special proteins called antibodies that seek out tumors. Beta radiation, or energetic electrons, emitted from radioactive decay of the rhenium can kill cancer cells and reduce tumor size significantly.
Rhenium-188 is expected to play an important role in treating bone pain. The rhenium can be attached to certain compounds that tend to settle in bones. "The treatment is expected to be considerably less costly than using strontium-89, rhenium-186, and other radioisotopes, which are currently used to treat bone pain," Knapp said, "and studies are in progress to verify this prediction. If the rhenium-188 treatment is found to be less expensive, it could help reduce health-care costs."
Patients having cancer of the breast or prostate often experience bone pain when cancer cells migrate from the primary tumor to the skeleton. The cancer cells can penetrate tissues surrounding the bone. It is believed that increased pressure on nerves in this tissue from both tumor cells and inflammation causes bone pain. The energy of the beta radiation from rhenium-188 reduces inflammation resulting from the presence of tumor cells, thus relieving bone pain.
For treatment of arthritis, the rhenium can be attached to compounds that are injected into the fluid of inflamed knees and other fluid-filled joints. According to Knapp, the energy released as the rhenium decays helps relieve the painful swelling and inflammation of arthritic joints.
"The use of radioisotopes for arthritis treatments is very common in Europe," Knapp said. "Such treatments are expected to be used more widely in the United States on an aging population."
ORNL, one of the Department of Energy's multiprogram research laboratories, is managed by Martin Marietta Energy Systems, which also manages the Oak Ridge K-25 Site and the Oak Ridge Y-12 Plant.