Pancreatic cancer has long confounded medicine by constructing within itself a biological fortress that repels the immune therapies that have reshaped oncology elsewhere. Researchers at the University of Chicago have now turned that fortress's own conditions against it, engineering a common gut bacterium to thrive precisely where tumors are most hostile and deliver immune-awakening therapy from within. The work, published in Science Advances, represents not merely a new drug but a new philosophy of delivery — using living organisms as targeted messengers in the body's most defended territories