HSV-tk + Valacyclovir Therapy in Combination With Brachytherapy for Recurrent Prostate Cancer

"The investigators insert a gene from a herpes simplex virus (HSV), which is a small piece of the basic structure of the virus, into the prostate gland tumor cells. The gene is called the thymidine kinase (tk) gene, which the cell uses to make a protein that can change valacyclovir, The way the tk gene will be transported into the tumor cells is by using a vector or vehicle to carry the tk gene into the cells. In this case the vector is a virus - an adenovirus. Scientists at the Department of Cell and Gene Therapy at The Methodist Hospital removed a portion of the adenovirus' genetic material that allows it to replicate so that it cannot cause infections. In place of the removed genetic material the scientists inserted the tk gene. Now the vector can carry the tk gene into tumor cells. When the vector/gene combination gets into tumor cells, it inserts itself into the cells' command center (nucleus) and tells the tumor cells to begin making thymidine kinase protein."