Based on earlier experiments, scientists had hoped the drug, ML464, would block the spread of a melanoma cell line into bones. They were pleasantly surprised to find that not only did the treatment block bone metastases, it also reduced the development of new tumors in organs like the liver, intestines and kidney.
"Bone metastases appear in 75 percent of all patients who develop metastatic breast and prostate cancer," says Katherine Weilbaecher, M.D., assistant professor of medicine and of pathology and immunology. "These metastatic tumors can be very painful and weaken the bone to the point of fracture."
Weilbaecher, the principal investigator in the new study, cautions that while it might be possible to use ML464 or other anti-platelet drugs to achieve the same effect in humans, such treatments have not been tested for their anti-metastatic effects yet and would leave patients at risk of bleeding. "This is a very exciting start, but it's just the beginning," says Weilbaecher. "The more we can understand this, the more narrowly we can target our therapy and explore the possibility that we might be able to block metastasis and only partially block clotting function."
The results are published today in the online early edition of the Proceedings of the National Academy of Sciences.
Weilbaecher's research group has been studying connections between bone metastases and osteoclasts, cells in bone marrow that normally break down the materials in bone for routine replacement. Scientists suspected that osteoclasts aid tumors' destruction of bone because they can make acid, an essential ingredient for breaking into bone.