NEW YORK, NY, USA I March 11, 2013 I ZIOPHARM Oncology, Inc. (Nasdaq:ZIOP), a biopharmaceutical company focused on the development and commercialization of new cancer therapies, today announced the initiation of a randomized, open label Phase 2 clinical study of Ad-RTS IL-12 in combination with palifosfamide to treat patients with non-resectable recurrent or metastatic breast cancer.

The two-part, multi-center U.S. study will enroll up to 68 patients with non-resectable, recurrent or metastatic breast cancer who have visible lesions or lesions accessible by injection. The study is designed to assess the safety and efficacy of the drug combination of Ad-RTS IL-12 and palifosfamide. Ad-RTS IL-12 is a targeted and controlled DNA-based therapeutic designed to express interleukin-12 (IL-12), a protein important for an immune response to cancer. Palifosfamide is a potent bi-functional DNA alkylating agent.

Part one of the two-part study will consist of a safety assessment for Ad-RTS IL-12 and palifosfamide, alone or in combination. Part two will consist of an efficacy evaluation of the Ad-RTS IL-12 only arm and the combination arm. The primary endpoint of the study is rate of progression-free survival at 16 weeks. Secondary endpoints include objective response rate, duration of response and evaluation of pharmacodynamic tumor markers.

"Several recent breakthroughs in cancer treatment are based on the hypothesis that the immune system plays a central role in suppressing both cancer’s growth and metastasis," said John Nemunaitis, M.D., lead investigator and Executive Medical Director, Mary Crowley Medical Research Center. "For breast cancer, the positive correlation of survival with immune response in the tumor elicited by non-immune treatments has only recently been elucidated, and this understanding hints at the potential for exciting new breakthroughs in this still underserved population. We look forward to participating in this study and to gaining further insight regarding the combined effect of Ad-RTS IL-12, a selectively controlled immunotherapy, and palifosfamide, a potent bi-functional DNA alkylating agent."

Jonathan Lewis, M.D., Ph.D., Chief Executive Officer of ZIOPHARM, added, "This study has exciting potential, both for this difficult-to-treat indication and for our synthetic biology platform, in which Ad-RTS IL-12 is the lead program. Building on preclinical work supporting a synergistic effect between Ad-RTS IL-12 and palifosfamide, and the clinical findings from our ongoing Phase 2 melanoma study, we believe the combination of Ad-RTS IL-12 and palifosfamide has the potential to be quite impactful in breast cancer."

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 two Phase 2 studies, the first for the treatment of advanced melanoma, and the second in combination with palifosfamide for the treatment of non-resectable recurrent or metastatic breast cancer. 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®, RTS®) 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.

Darinaparsin (ZIO-101) is a novel mitochondrial-and hedgehog-targeted agent (organic arsenic) currently in ongoing studies with Solasia Pharma K.K.

ZIOPHARM’s operations are located in Boston, MA, and New York City. Further information about ZIOPHARM may be found at www.ziopharm.com.

SOURCE: ZIOPHARM