Doctors may someday be able to adjust interleukin-12 (IL-12) levels in melanomas at will, according to results of an ongoing clinical trial presented at Melanoma Bridge 2013 Conference in Naples, Italy. IL-12 is an immune system protein that can shrink melanomas, but also has nasty side effects. The experimental immunotherapy entails injecting tumors with a virus that does not cause diseas, and that has been engineered to produce the IL-12 when people take a drug called veledimex. In the phase I/II trial of 21 people with melanomas that had been injected with this engineered virus, IL-12 production turned on when they took veledimex and turned off when they stopped. Depending on the dose, veledimex increased IL-12 production by 1,000 to 100,000 times.