Last year, a PNAS study showed that the surfaces of many tumor cells have a protein called CD47, which protects them from the immune system. But when these tumors are treated with a drug that inhibits CD47, they get attacked by immune system cells. The researchers transplanted seven kinds of human tumors into mice and treated them with the CD47-targeting drug. All of the tumors—bladder, brain, breast, colon, liver, ovary, and prostate—shrank or disappeared, which kept them from spreading. Now, the research will progress to clinical trials, thanks to a $20 million grant from the California Institute for Regenerative Medicine. CD47 was originally found on leukemia and lymphoma cells; the initial trial will target the stem cells that perpetuate acute myeloid leukemia. This cancer of the blood and bone marrow is fatal within months if untreated, and the 5-year survival rate is only 30% to 40%, even with aggressive treatments including chemotherapy and bone marrow transplants.