Immune therapy is gaining popularity in cancer care and the next frontier is creating “living drugs” from blood to destroy tumours. An earlier wave of immunotherapy drugs- the kind used to treat former US President Jimmy Carter's cancer- unmasks tumours so that “T-cells,” a kind of immune cell, can strike. Now doctors are reprogramming those T-cells to make them stronger and better at seeking out cancer. The process begins with removing T-cells from the patient's blood. One of the ways researchers are altering them is through a virus engineered to instruct the T-cells to grow a chimeric antigen receptor. These T-cells then zero in on a specific type of cancer. Only major cancer centres are testing the living drugs in trials and they can hit the market later this year for some blood cancers.