King Abdullah University of Science and Technology (KAUST) researchers have found that an antibody drug that targets a protein called CD44 on cancer stem cells may help treat acute myeloid leukemia (AML). AML, also known as acute nonlymphocytic leukemia, is a blood cancer in which immature blood cells fail to mature and therefore cause harmful effects. Although AML is rare, it can become fatal quickly if it is not treated, and it is the second-most common form of leukemia in children, and is the most common type of leukemia among adults. AML is a devastating form of cancer, whose five-year survival rate is only 30 percent. In AML, the process by which myeloid stem cells differentiate into mature white blood cells is disrupted, which leads to an overproduction of immature white blood cells and affects the development of normal blood cells. Leukemic stem cells express a protein known as CD44 on their surface. It has already been found that antibodies directed against CD44 cause the stem cells to mature and significantly decrease leukemic repopulation. But the mechanism behind this process is not understood. To answer this question, KAUST researchers looked at the signaling pathways that are altered by treatment with a CD44-directed antibody. They tested the antibody in both human AML cells and animal models, and found that the inhibition of CD44 by the antibody suppressed the PI3K and the mTOR pathways, both of which are strongly involved in the abnormal growth of cancer cells. The researchers also discovered that the antibody inhibited different complexes that induce mTOR. Previous research has shown that drugs that only block one of these complexes can't treat AML. The antibody tested in the new study may help to completely shut down the mTOR signaling, and thus prevent cancer growth. Moreover, the anti-CD44 antibody did not affect normal cells. Scientists have known for a while that inhibiting CD44 with some specific anti-CD44 monoclonal antibodies can reverse the differentiation blockage of leukemic cells. And lots of effort have been made to develop therapeutic antibodies. The antibody used in this study has shown promise in treating AML, but more research is needed. By the way, CusAb is a manufacturer of Recombinant fam171a2 and other transmembrane proteins.