The US Department of Defense has awarded a three-year, $1.6 million contract to Southwest Research Institute to develop bone-targeting nanocapsules for fighting myeloma and metastatic bone cancers. These secondary bone cancers are more common and deadly than primary bone cancer, which is rare.

The programme is intended to determine, in pre-clinical studies, the potential of skeletally targeted proteasome inhibitors as an effective and selective treatment for myeloma. Proteasome inhibitors have been under study as a treatment for myeloma and other cancers. They limit the function of the proteasome, part of the cell machinery responsible for cleaning up proteins involved in cellular function once they have completed their task.

"Our technology can potentially increase the localization of the drug in the bone microenvironment," said Dr. Neal K. Vail, a principal engineer in the Microencapsulation, Nanomaterials and Process Engineering Department in SwRI's Chemistry and Chemical Engineering Division. "We formulate our bone-targeting nanocapsules to seek out areas of active bone resorption, which is in high gear in myeloma. This allows us to localize the drug at the site of the cancerous lesion where it can be the most effective," Dr Vail added.

Due to their function, proteasome inhibitors can have diverse and serious side effects. However, if they could be targeted to a specific site to act on the necessary cells, their effectiveness in treating cancer could be greatly increased.

The three-year study will formulate bone-targeting nanocapsules, determine their in vivo biodistribution and evaluate the success of using them to target proteasome inhibitors to myeloma lesions. In collaboration with The University of Texas Health Science Centre at San Antonio (UTHSC-SA), SwRI will use combinations of radiolabel imaging and micro-computed tomography to map the distribution of the nanocapsules. In collaboration with Osteoscreen Inc., SwRI will examine the potential of the targeted therapy using a myeloma cell line engineered to fluoresce. The Walter Reed Army Medical Centre in Washington will also contribute to the programme, the release says.

"Bone targeting has the potential to significantly reduce systemic exposure, reduce dosage requirements, and mitigate possible toxicity of proteasome inhibitors and other agents," Vail said adding, "This technology has tremendous potential for new therapies for bone pathologies including osteoporosis, fracture repair, implant fixation and tissue engineering."

The Institute completed an internal research programme on the development of nanocapsule vehicles for targeted delivery of therapeutic agents in 2003. The research focused on targeted delivery to bone.

This contract has been awarded through the Congressionally Directed Medical Research Programs.

More than 500,000 people will die from cancer in 2005, and most of these patients will have been affected by metastasis, cancer that started elsewhere in the body and spread to the bone. Myeloma, a blood-borne disease that is uniformly fatal, affects approximately 70,000 Americans and accounts for about 2 percent of all cancer deaths.