- A new cancer treatment involves collecting white blood cells from an individual, modifying them to secrete IL-2 and target the ESO-1 protein expressed on some cancers, and returning them to the body. The cells may then be able to seek out the cancer cells and destroy them. Some kinds of cancer contain a protein called ESO-1, which is found on the surface of the cells. Doctors want to modify white blood cells to have an anti-ESO-1 effect, and use them to treat the cancer that has the ESO-1. In addition to adding genes that target the ESO-1 protein to the cells, the genes for IL-12 are added to the cells. IL-12 is a protein that stimulates the immune system. This type of therapy is called gene transfer.