A genetically engineered drug shows great early promise in tracking down and killing a rare leukemia, raising doctors' hopes in the long quest for a magic bullet against cancer. Eleven of the 16 patients treated in a study of the drug were left with no readily detectable trace of the disease. The experimental drug relies on a piece of antibody from a mouse's immune system to latch tightly onto the cancer cells, while shunning normal cells. A bacterial poison fused to the antibody is then carried inside the cancer cells and kills them.

USA Today.