Well, ScienceNow reports promising new data suggests such a drug could be on the horizon. Scientists discovered a single drug has been proven to train the immune system to kill nearly every type of cancer in mice. Scientists tested the drug by transplanting human tumors in mice. The drug works by blocking a protein called CD47, which was found in every type of human primary tumor they tested. With more research, it could be possible to one day treat cancer with this single drug.