ZIOPHARM Presents ZIO-101 Data at Bone Marrow Transplant Meeting.

Clinical Activity in Multiple Myeloma Supports Utility after Autotransplant 

KEYSTONE, Colo. -- ZIOPHARM Oncology, Inc. (NASDAQ: ZIOP), announced findings from a phase I study of ZIO-101, a proprietary organic arsenic, showed that 43 percent of relapsing, progressing multiple myeloma patients experienced stable disease and that the drug was well tolerated in all 14 patients in the study group. There was no clinically significant bone marrow suppression in patients with either prior or no prior transplant. The patients in the study group had failed a median of eight prior treatments. Dr. Mohamad Hussein of the Moffitt Cancer Center and colleagues presented the findings at the Bone Marrow Transplant Tandem meetings being held in Keystone, Colorado. These data suggest that ZIO-101 may be active in myeloma, and may also be useful in patients who suffer a disease relapse post-bone marrow transplant.

"High-dose therapy is commonly used to treat multiple myeloma, but unfortunately, most recipients relapse," commented Dr. Hussein. "Subsequent treatment can be difficult because of limited bone marrow reserve. The potential to use ZIO-101 in this setting is very promising and could be significant as this remains an area of unmet medical need."

Data from the phase I study in multiple myeloma showed 6 of 14 patients achieved at least stable disease (SD). Two patients have had SD for greater than six months duration and one, who had a prior transplant, has had five months' duration. There was no clinically relevant QT prolongation and unlike many other drugs used to treat multiple myeloma, no clinically relevant bone marrow suppression in the patient group. A phase II study that is testing two dosing schedules is ongoing, treating patients with myeloma who have failed at least two prior treatments.

About ZIO-101

ZIO-101 is a proprietary small molecule organic arsenic licensed from The University of Texas M. D. Anderson Cancer Center and Texas A&M University. ZIO-101 induces cell cycle arrest and cell death by targeting several cellular pathways essential for cell survival. Exposure to ZIO-101 has a direct as well as indirect effect on mitochondrial functions, resulting in depletion of energy supply to the cell and induction of apoptosis (programmed cell death). Increase in intra-cellular Reactive Oxygen Species enhances this effect on mitochondrial functions and consequently the activation of the signal transduction pathway leading to apoptosis. In addition, ZIO-101 interrupts the cell cycle at the G2/M phase of tumor cells inducing cell death through this pathway as well.

About ZIOPHARM Oncology, Inc.

ZIOPHARM Oncology, Inc. applies new insights from molecular and cancer biology to understand the efficacy and safety limitations of approved and developmental cancer therapies and identifies proprietary and related molecules for better patient treatment. For more information, visit www.ziopharm.com.

Forward-Looking Safe Harbor Statement:

This press release contains forward-looking statements for ZIOPHARM Oncology, Inc. that involve risks and uncertainties that could cause the Company's actual results to differ materially from the anticipated results and expectations expressed in these forward-looking statements. These statements are based on current expectations, forecasts and assumptions that are subject to risks and uncertainties, which could cause actual outcomes and results to differ materially from these statements. Among other things, there can be no assurance that any of the Company's development efforts relating to its product candidates will be successful, or such product candidates will be successfully commercialized. Other risks that affect forward-looking information contained in this press release include the possibility of being unable to obtain regulatory approval of the Company's product candidates, the risk that the results of clinical trials may not support the Company's claims, and risks related to the Company's ability to protect its intellectual property and its reliance on third parties to develop its product candidates. The Company assumes no obligation to update these forward-looking statements, except as required by law.

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