From the WSJ:
Researchers reported fresh evidence Wednesday that using gene therapy to manipulate the immune system is emerging as a promising new strategy in the fight against cancer.
Five patients with a lethal leukemia achieved complete and rapid remissions after the treatment, in which cells from their own immune systems were genetically altered to specifically attack the disease.
While the study was small, researchers were impressed that the cancer was eradicated in all five patients. In one patient, all evidence of the cancer was gone eight days after treatment.