Ziopharm Oncology Inc., of Boston, reported results from human and laboratory studies demonstrating that precise control of interleukin-12 (IL-12) gene expression levels can be achieved using Germantown, Md.-based Intrexon Corp.'s Rheoswitch Therapeutic System. When IL-12 expression was "switched on," it led to expression and an immune response, characterized by an increase in tumor-infiltrating lymphocytes with systemwide immune activation, resulting in antitumor effects in both injected and systemic non-injected legions in phase I and phase II studies of Ad-RTS-IL-12 in subjects with melanoma and breast cancer. Data, presented at the American Society of Gene and Cell Therapy meeting in Washington, also showed antitumor and anticancer stem cell effects of Ad-RTS-IL-12 in a glioma model.