For the production of CAR-T cells, T cells belonging to the white blood cells (lymphocytes) are taken from the patient. The T cells are provided outside the body with the gene of a chimeric antigen receptor (CAR, Chimeric Antigen Receptor) by means of a viral gene transfer vector, then multiplied and administered intravenously to the same patient.

Six approved T-cell medicines are approved in the EU. They are already used in the treatment of certain types of blood cancer. The Paul-Ehrlich-Institut (PEI), Federal Institute for Vaccines and Biomedicines, was involved in the benefit-risk assessment of CAR-T cell medicines.