Via EurekAlert!: "Adoptive immunotherapy is targeted to situations when the immune system fails to detect a disease [such as cancer]. The adoptive immunotherapy strategy is to harvest T cells from the patient, engineer them to spot the disease and then send them back in, like police detectives with a reliable tip. A major drawback, however, has been that the T cells still need to call for back-up forces from a variety of other cell types in the body, but they can't. They die out quickly without doing enough good. The new approach is to further engineer the T cells to be able to support themselves rather than relying on other immune cells [and] to insert the ability to switch that self-support on or off, to ensure that they don't grow out of control. That way, the T cells can persist in fighting the disease without becoming a cancer themselves. ... This is an integration of a cell-based therapy application with new synthetic biology tools that have come up from foundational research. ... Generally, the results showed that their engineering produced healthier, faster-growing populations of the T cells, until the drugs were withdrawn and growth shut down. In the human cell cultures, for example, the technology led to a 24 percent increase in the live T-cell population compared to controls and 50 percent fewer cells dying off."