Researchers from Cornell University (NY, USA) have discovered that metastatic prostate cancer in mice can be almost eliminated using cancer-killing proteins that are transported through the bloodstream by leukocytes. This therapy attacks and kills cancer cells circulating in the bloodstream, preventing the formation and growth of metastatic tumors.
The study is due to be published in the February issue of the Journal of Controlled Release.
“The therapy is remarkably effective in vivo and shows several advantages, such as no toxicity and getting good results in very low dosages,” explained author Michael King of Cornell’s Meinig School of Biomedical Engineering. “It was our wildest dream to completely prevent the spread of prostate cancer. And that’s what happened in this system.”
The researchers produced nanoliposomes with the TRAIL protein that are able to attach to leukocytes. As the leukocytes travel in the bloodstream, the TRAIL protein kills the tumor cells, leaving the bloodstream cancer free. When investigated in mice with prostate cancer, the researchers found that this treatment prevented secondary tumors and also decreased the size of the primary tumor.
In this study, no metastases were observed in the treated mice; however, the circulating tumor cell count, although greatly decreased, was not zero. This led to the researchers suggesting that complete elimination of circulating tumor cells is not required to observe a positive outcome.
Additionally, it was found that even a single dose of therapy, delivered late in the disease course can substantially reduce the number of circulating tumor cells.