Could approved drugs be repurposed to discover new treatments for chronic and rare diseases? Denise Faustman, Director of Immunobiology at Massachusetts General Hospital East, has begun a Phase II clinical trial to test if a tuberculosis vaccine can be used to treat Type I diabetes. And geneticist Christina Waters’ organization, RARE Science, works with patients and researchers to match drugs for rare diseases. Faustman and Waters discuss the potential of this approach to treatment.