Cancer immunotherapy company tries to explain deaths in recent trial

A chimeric antigen receptor–T cell (orange) on a cancer cell (green)
More than a year after five leukemia patients died from an experimental treatment involving genetically engineered immune cells, its developer believes it has a better handle on what went wrong—and possibly how to prevent a repeat of the tragedy. “product variability” made for a lethal combination that led to fatal brain swelling. The company says it is now using insights from its analysis to inform work on a modified cell treatment that is in early-stage clinical trials.The treatment that Juno was testing, known as chimeric antigen receptor (CAR)-T cell therapy, equips a patient’s own immune cells with a new surface protein that allows them to home in on and kill cancer cells. It’s an approach promising enough that it was honored as part of Science ’s