T-cell therapy is a rapidly growing field of personalized medicine, attracting the interest of venture capitalists and pharmaceutical companies alike. Such therapies exploit T cells’ innate abilities to protect against pathogens as well as to seek and destroy cancerous cells. Although many different forms of T-cell therapies are currently in clinical trials, they all follow a common protocol: T cells are isolated from a patient, modified and expanded in a laboratory setting, and then infused back into the same patient…