Illustration showing chimeric antigen receptor (CAR) T cells (blue) attacking multiple myeloma cells (translucent) in a blood vessel surrounded by red blood cells (red discs). Multiple myeloma is a type of cancer that occurs when a type of white blood cell called a plasma cell becomes abnormal and cancerous. The cancerous plasma cell divides and multiplies creating large amounts of abnormal antibodies. These abnormal antibodies can affect multiple parts of the body, causing pain and weakening of the bones amongst other symptoms. CAR-T therapy is a type of immunotherapy that genetically modifies a patients own T cells, a form of white blood cell, to recognise and destroy cancer cells.