Until now, researchers have lacked the tools to create a targeted cell therapy approach that could work on all the different forms of blood and bone marrow cancers. A new solution could solve a major problem in immunotherapy, namely the inability to target surface markers present on both cancerous and healthy cells. In the study, published today in Science Translational Medicine, researchers used CAR T cells engineered to target CD45, a surface marker present on almost all blood cells, including almost all blood cancer cells. Since CD45 is also found on healthy blood cells, the research team used CRISPR base editing to develop a method called “epitope editing” to overcome the challenges of an anti-CD45 strategy, which would otherwise result in potentially lethal low blood counts and threatening side effects. The modified version of CD45 still functions, but differs sufficiently from normal CD45 for anti-CD45 CAR T cells not to recognize and attack it. This study lays the foundations for a more universal approach that could potentially extend CAR T cell therapy to all blood cancers.