Some forms of prostate cancer thrive on the male hormone androgen, and thus a form of prostate cancer treatment is to use compounds that block androgen's effects to stop the growth of tumorous cells. However, there is presently no treatment available to extend the survival of men with prostate cancer that is androgen-refractory. And unfortunately, the doses of chemotherapeutic drugs required to overcome androgen-refractory prostate cancer are so large that they are prohibited by their toxicity.
Now, scientists at Merck Research Laboratories in Pennsylvania (Nature Medicine, 01 Nov 2000) have devised a way to increase the dose of one chemotherapeutic drug, doxorubicin to such a level that it can be tolerated by prostate cancer patients and also be high enough to destroy cancerous cells.
Raymond Jones and colleagues attached doxorubicin to a peptide in such a way that the linking bond can be cleaved by prostate specific antigen (PSA), which is over-expressed in prostate cancer tissue.
When the doxorubucin conjugate was tested in mice, it was found to be 15 times more potent than ordinary doxorubucin at blocking the growth of human prostate cancer tumors. It was also less toxic to ordinary tissue because it is activated only in the presence of PSA, which is largely confined to the prostate gland. The authors conclude, "These experiments support the use of PSA-hydrolyzable peptide conjugation for the treatment of prostate cancer in man."
Dr. Raymond Jones:
Merck Research Laboratories
Bldg. 16 Room 310
PO Box 4
West Point, PA 19486
(C) Nature Medicine press release.
Message posted by: Trevor M. D'Souza