For years, one of the most powerful weapons against certain blood cancers, called CAR-T cell therapy, has required an elaborate process: Doctors extract a patient’s immune cells, ship them to a specialized facility where they’re genetically reprogrammed to fight cancer, then ship them back for infusion back into the patient’s bloodstream. This has revolutionized cancer treatment, but it takes weeks and can cost hundreds of thousands of dollars, placing it out of reach for many of the patients who need it most.

In experiments using mice with humanized immune systems, the researchers used the method to successfully treat aggressive leukemia, multiple myeloma, and even a solid tumor.