In a recent NY Times science article, there was a young girl at the age of six who had given up all hopes in her fight against leukemia due to relapsing twice after chemotherapy. In her battle against cancer, she enrolled in an experimental treatment that nearly killed her. With the use of an AIDS inactivated virus, her immune cells were reprogrammed to kill cancer cells. They do this by removing many of the patients T cells and inserting cancer fighting genes into them. They use an inactive form of AIDS because as we know it targets T cells and can transport the genes to the target. Once put into the patients bloodstream, it will hopefully multiply and prevent the cancer from growing. The T cells go after B cells and start to attack thus weakening the patients immune system. The depletion affects both healthy and cancerous B cells so the patient needs to be treated with immunoglobulins in order to keep up the immune system. The weakening of the immune system is due to "cytokine storm" which is when so many chemicals are being released there is a negative affect in the body.
After the treatment, she has not has any remission or signs of cancer but this is not the case for every individual in the study. It could be due to them having an immune response to the vector used but it is undetermined as to why it works for some and not others which is why a cure has not been announced. It is a promising treatment as many are researching and putting money into the effort to discover new properties. T-cell engineering does not cost as much as bone marrow transplantation so it does look like a promising avenue.