Therapy seeks and destroys prostate cancer in mice

A single dose of the experimental therapy—even delivered very late in the course of the disease—dramatically reduced the number of tumor cells. "This suggests that it may never be too late to help," says Michael King. (Credit: iStockphoto)

A new therapy uses white blood cells to ferry cancer-killing proteins through the bloodstream. Tests show it virtually eliminates metastatic prostate cancer in mice.

“The therapy is remarkably effective in vivo and shows several advantages, such as no toxicity and getting good results in very low dosages,” says senior author Michael King, professor of biomedical engineering at Cornell University. “It was our wildest dream to completely prevent the spread of prostate cancer. And that’s what happened in this system.”

Metastasis is the spread of cancer cells from one tumor to other organs of the body, such as the lungs, the liver, the spleen, and the kidneys. While surgery and radiation treat primary tumors, it remains difficult to detect and reach metastatic cancer cells—which makes the treatment of spreading cancer more treacherous and problematic, King says.

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Researchers created nano-sized liposomes with a protein that attaches to leukocytes (white blood cells). The liposomes are about one-one hundredth the size of the white blood cells. As the white blood cells travel throughout the bloodstream, the hitchhiking protein kills the tumor cells—leaving the bloodstream free of cancer.

As reported in the study, published in the Journal of Controlled Release, prostate cancer cells were implanted into the prostate of male mice to let the tumors grow. The treatment prevented secondary tumors, and the primary tumor shrunk in size.

While treated mice showed no metastases, the circulating tumor cell count remained greatly reduced but not completely zero, which leads scientists to believe “you don’t have to be perfect in completely eliminating circulating tumor cells to observe a very good outcome,” King says.

Further, the researchers discovered that a single dose of the therapy—even delivered very late in the course of the disease—can substantially reduce the number of tumor cells. “This suggests that it may never be too late to help,” King says.

The National Cancer Institute funded the research.

Source: Cornell University