NEW YORK, Nov. 7, 2012 (GLOBE NEWSWIRE) -- ZIOPHARM Oncology, Inc. (ZIOP), a drug development company employing small molecule and synthetic biology approaches to cancer therapy, announced today results from a preclinical study demonstrating the long-term persistence and anti-tumor effects of a new synthetic biology approach (DNA/cell plasmid) to controlled protein production in vivo. This embedded controlled bioreactor study was presented at the EORTC-NCI-AACR International Conference on Molecular Targets and Cancer Therapeutics, taking place November 6-9 in Dublin, Ireland, and was conducted jointly by ZIOPHARM and Intrexon Corporation, a synthetic biology company that utilizes its proprietary technologies to provide control over cellular function, ZIOPHARM's exclusive channel partner for the development of DNA therapeutics.

"These data demonstrate the potential of our disruptive technologies, including UltraVector(R), RTS(R), and our cell engineering capabilities," said Samuel Broder, M.D., Chairman of Intrexon's Therapeutic Opportunities Committee and former Director of the NCI (National Cancer Institute). "By using tightly controlled, purpose-built, cellular protein factories, we open up therapeutic windows for a broad array of proteins. This study demonstrates the long-term persistence of this approach, with sustained protein production and therapeutic anti-tumor efficacy drawing from only a single intramuscular administration of plasmid DNA."

Hagop Youssoufian, M.D., President of Research and Development and Chief Medical Officer of ZIOPHARM, said, "These data are very exciting, as they provide us with another systemic approach for the delivery of therapeutic proteins to a target cancer using engineered DNA transgenes. We have already seen the potential in the clinic of delivering these transgenes using dendritic cells and viral vectors. Each approach gives us a means of optimizing the timing, concentration and location of therapeutic proteins; ultimately allowing us to dislocate cancer's signaling networks with minimal interference to our natural systems. We look forward to further our study of therapeutic anti-cancer proteins delivered via this revolutionary technology."

For this study, a RheoSwitch(R)-regulated (RTS(R)) interferon alpha (IFN) plasmid transgene was evaluated as a means of widening the therapeutic window of IFN in a melanoma mouse model. DNA vectors for the controlled expression of murine or human IFN were optimized using Intrexon's UltraVector(R) platform, then transfected into human fibrosarcoma cells or myoblasts, forming RTS-IFN plasmids. These plasmids were subsequently electroporated into the skeletal muscle of normal or melanoma tumor-bearing mice, and then activated using an oral activator ligand (AL).

A single intramuscular electroporation of RTS-IFN combined with daily oral activator ligand treatment led to significant tumor growth inhibition, comparable to chemotherapy or repeated bolus injection with recombinant mIFN protein, but without overt toxicity, as assessed by body weight change and survival. Treatment with pRTS-IFN resulted in sustained serum and tumor expression of mouse IFN for approximately 4 months (study termination), as well as expression of the angiogenic biomarker IP-10, and activation of T cells (CD4 and CD8), NK cells, and dendritic cells.

About ZIOPHARM Oncology, Inc.:

ZIOPHARM Oncology is a biopharmaceutical company focused on the development and commercialization of new cancer therapies. The Company's clinical programs include:

Palifosfamide (ZIO-201) is a potent bi-functional DNA alkylating agent that has activity in multiple tumors by evading typical resistance pathways. Palifosfamide is in the same class as bendamustine, cyclophosphamide, and ifosfamide. Intravenous palifosfamide is currently being studied in a randomized, double-blinded, placebo-controlled Phase 3 trial (PICASSO 3) for the treatment of first-line metastatic soft tissue sarcoma and is also in a pivotal Phase 3 trial (MATISSE) for first-line metastatic small cell lung cancer. Additionally, the Company is developing an oral capsule form of palifosfamide.

Ad-RTS IL-12 is currently being tested in a Phase 2 study. Ad-RTS IL-12 uses synthetic biology to enable controlled, local delivery of therapeutic interleukin-12 (IL-12), a protein important for an immune response to cancer. ZIOPHARM's DNA synthetic biology platform is being developed in partnership with Intrexon Corporation and employs an inducible gene-delivery system that enables controlled, local delivery of genes that produce therapeutic proteins to treat cancer. This is achieved by placing IL-12 under the control of Intrexon's proprietary biological "switch" (the RheoSwitch Therapeutic System(R), RTS(R)) to turn on/off the therapeutic protein expression at the tumor site.

Indibulin (ZIO-301) is a novel, tubulin binding agent that is expected to have several potential benefits, including oral dosing, application in multi-drug resistant tumors, no neuropathy and a tolerable toxicity profile. It is currently being studied in a Phase 1/2 trial in metastatic breast cancer.

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ZIOPHARM Oncology Presents Systemic, DNA/Cell Plasmid Therapy Showing Long-Term Persistence and Anti-Tumor Effects at ...