IN 2010 AN American girl called Emily Whitehead developed a form of leukaemia that is usually terminal. She was five years old. Two years later, she became the first paediatric patient to be offered a form of treatment called CAR–T, in which the body’s immune system is reprogrammed to attack cancerous cells. The treatment worked. A documentary film about her journey, released in 2022, was called “Of Medicine and Miracles”.