CAR T cell cancer immunotherapy. Illustration of the stages involved in CAR (chimeric antigen receptor) T cell immunotherapy, a process that is being developed to treat cancer. The sequence runs from top left to centre right to lower left. The first stage (upper left) involves taking T cells (blue, a type of white blood cell) from the patient. These are then treated (upper right) with a virus (red) that transfers DNA (deoxyribonucleic acid, helical) to the T cells (a form of genetic engineering) that results in them producing chimeric antigen receptor (CAR) proteins. These proteins will be specific to the patient's cancer. These modified T cells are then grown in the laboratory (petri dish at lower right) and use to treat the patient (lower left). The technique is known as adoptive cell transfer (ACT).