We modified the virus so that it replicates only in the presence of an active prostate-specific antigen and, therefore, is highly specific to prostate cancer. We also tested its efficacy in a tumor model in vitro," Subbiah said. "The recombinant virus efficiently and specifically killed prostate cancer cells, while sparing normal human cells in the laboratory, but it would take time for this to move from the discovery phase to a treatment for prostate cancer patients."