British scientists report that genetically modified herpes simplex virus can eliminate or shrink tumors in terminally ill patients. Scientists have hailed the “Trojan horse” treatment using a modified herpes virus to kill cancer cells as a “wonder of genetic engineering”, with an early trial already prolonging the lives of those infected in the end. A new oncolytic virotherapy being tested at three hospitals in the UK injects RP2, a modified version of the herpes simplex virus (HSV), directly into patients’ tumors to kill the cancer. The modified virus attacks cancer in two ways, first by invading cancer cells and causing them to explode, and then by stimulating cytotoxic T cells in the immune system to kill cells infected with the virus.