University of Pennsylvania Cancer Center
Last Modified: May 18, 1998
A certain herpes gene may help fight prostate cancer, according to the first study to demonstrate that gene therapy is safe and active against prostate cancer. This phase I trial examined 18 patients who had local recurrence of prostate cancer following initial treatment with radiation.
The herpes gene (thymidine kinase) activates a normally inactive antiviral drug called ganciclovir. Because human cells do not normally contain this gene, they are resistant to ganciclovir's effects. When this gene was successfully transferred into prostate cancer cells, however, the ganciclovir was activated, thereby killing the cancerous cells.
This phase I study was designed only to test safety and study different dosing levels. Nonetheless, three of the 18 patients in the study showed a significant decrease in PSA levels -- an indication that the prostate cancer may be diminishing in size. One patient showed no sign of cancer after biopsy.