ZIOPHARM Shares Jump 9+% as Preclinical Data Shows Anti-Tumor Effects in Murine Model

ZIOPHARM Oncology, Inc. ZIOP, a biopharmaceutical company focused on the development and commercialization of new cancer therapies, announced today the presentation of results from a study in a breast cancer murine model demonstrating the anti-tumor effects and tolerability of Ad-RTS-mIL-12, a viral vector DNA-based therapeutic for the controlled, local expression of IL-12, an important protein for enhancing antitumor immunity. The data were presented at the American Association for Cancer Research 2013 Annual Meeting (AACR 2013) taking place April 6-10, 2013 in Washington, D.C. The study was conducted jointly by ZIOPHARM and Intrexon Corporation, a synthetic biology company that utilizes its proprietary technologies to provide control over cellular function. ZIOPHARM is Intrexon's exclusive channel partner for the development of in vivo therapeutics in oncology. For the study, intratumoral administration of Ad-RTS-mIL-12 (Ad) was examined in a 4T1 BALB/c mouse breast carcinoma model. Production of murine IL-12 was controlled using Intrexon's RheoSwitch Therapeutic System^® (RTS^®) platform and oral administration of the activator ligand INXN-1001 (AL). Oral administration of AL was found to elicit a dose-related increase in plasma AL levels, which correlated with increasing tumor levels of AL. The increase in tumor AL levels in combination with Ad in turn resulted in a dose-related increase in expression of mIL-12 in the tumor, with minimal increase in serum mIL-12. This increase in AL-regulated tumor IL-12 levels correlated with an increase in tumor-infiltrating CD4^+ and CD8^+ T cells in and adjacent to the tumor, concomitant with a decrease in tumor regulatory T cells. This resulted in a dose-related decrease in tumor growth rate. Moreover, the therapeutic strategy appears to be well tolerated, as no change in clinical signs or body weight was observed in the treated animals when compared with vehicle alone.