This study is an investigational approach that uses immune cells, called "T cells", to kill leukemia. These T cells are removed from blood, modified in a laboratory, and then put back in the body. T cells fight infections and can also kill cancer cells in some cases. However, right now T cells are unable to kill the cancer cells. For this reason we will put one gene into the T cells that allows them to recognize and kill the leukemia cells. This gene will be put in the T cells by a weakened virus. The gene will produce proteins in the T cells that help the T cells recognize the leukemia cells and possibly kill them. The doctors have found that T cells modified in this way can cure an ALL-like cancer in mice.