Researchers say they have created a drug that has killed every kind of cancer tumor it has come in contact with, according to Science Magazine. The antibody treatment works by blocking a protein called CD47 which tricks the body into not destroying cancerous cells. After the protein is blocked, the body can then recognize the cancer cells as invaders and attack. While the research is seen as a step closer to discovering a treatment that can cure all cancers, the drug has only been tested on mice and will need to prove itself on humans before it can be available to patients. This may take a few years. The research team has been given the green light and recently received a four-year, $20 million grant to conduct human clinical trials. Research for this new drug started a decade ago when biologist Irving Weissman at Stanford University was studying leukemia cells. He found that that leukemia cells produce higher levels of the CD47 protein than healthy cells. CD47 acts as a "don't-eat-me" signal, instructing the body to not eat harmful cells. Cancers take advantage of this signal to trick the immune system into ignoring them. Weissman's research showed that blocking CD47 can cure more than just blood cancers. The drug can also shrink or cure human breast, ovary, colon, bladder, brain, liver and prostate tumors that have been transplanted into mice. The treatment forced the mice's immune system to kill the cancer cells. This means this single drug could cure a variety of cancers and prevent cancers from spreading in the body.