ZIOPHARM Provides Update Regarding Phase I Study of Gene Therapy Candidate Ad-RTS-hIL-12 in Brain Cancer BOSTON, MA

ZIOPHARM Provides Update Regarding Phase I Study of

Gene Therapy Candidate Ad-RTS-hIL-12 in Brain Cancer

BOSTON, MA July 19, 2016 ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP) today provided an update regarding the Company s ongoing

multicenter Phase 1 study of Ad-RTS-hIL-12 + orally administered veledimex in recurrent or progressive glioblastoma (GBM) or grade III malignant glioma.

The patient death resulting from intracranial hemorrhage in the third cohort of this Phase I study was deemed unrelated to study drug following the receipt

and analysis of additional information by the sponsor and the study s Safety Review Committee. As with all study events, the Company expects to report the data to the U.S. Food and Drug Administration in accordance with the study s

protocol and applicable regulations. As previously announced, the study remains open for enrollment. The Company expects to provide further updates on the progress of the study, including longer-term survival follow up, at an appropriate meeting

Recurrent GBM is a devastating disease with an expected overall survival that remains far too short as this case

illustrates, said Francois Lebel, M.D., Executive Vice President, Research and Development, Chief Medical Officer at ZIOPHARM. Preliminary overall survival in this study, including a median follow-up of over 8 months in the first dose

cohort, remain encouraging, and we will continue to work diligently toward understanding the full potential of Ad-RTS-hIL-12 + veledimex in this disease, with the goal of providing safe and effective treatment options to these patients.

Glioblastoma is an aggressive primary

brain tumor affecting approximately 74,000 people worldwide each year.i, ii Recurrent glioblastoma is an aggressive cancer with one of the lowest 3-year survival rates, at 3%, among all cancers.iii For patients who have experienced multiple recurrences the prognosis is particularly poor, with a median overall survival (OS) of 6-7 months, while OS in patients that have failed temozolomide and

bevacizumab, or equivalent salvage chemotherapy, is approximately 3-5 months.iv, v

ZIOPHARM Oncology, Inc.:

ZIOPHARM Oncology is a Boston, Massachusetts-based biotechnology company employing novel gene expression, control and cell

technologies to deliver safe, effective and scalable cell- and viral-based therapies for the treatment of cancer. The Company s immuno-oncology programs, in collaboration with Intrexon Corporation (NYSE:XON) and the MD Anderson Cancer Center,

include chimeric antigen receptor T cell (CAR-T) and other adoptive cell-based approaches that use non-viral gene transfer methods for broad scalability. The Company is advancing programs in multiple stages of development together with Intrexon

Corporation s RheoSwitch Therapeutic System technology, a switch to turn on and off, and precisely

modulate, gene expression in order to improve therapeutic index. The Company s pipeline includes a number of cell-based therapeutics in both clinical and preclinical testing which are

focused on hematologic and solid tumor malignancies.

Forward-Looking Safe-Harbor Statement:

This press release contains certain forward-looking information about ZIOPHARM Oncology, Inc. that is intended to be covered by the safe harbor for

forward-looking statements provided by the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts, and in some cases can be identified by terms such as

may, will, could, expects, plans, anticipates, and believes. These statements include, but are not limited to, statements regarding the progress, timing and results

of preclinical and clinical trials involving the Company s drug candidates, and the progress of the Company s research and development programs. All of such statements are subject to certain risks and uncertainties, many of which are

difficult to predict and generally beyond the control of the Company, that could cause actual results to differ materially from those expressed in, or implied by, the forward-looking statements. These risks and uncertainties include, but are not

limited to: whether chimeric antigen receptor T cell (CAR T) approaches, Ad-RTS-hIL-12, TCR and NK cell-based therapies, or any of our other therapeutic candidates will advance further in the pre-clinical or clinical trials process and whether and

when, if at all, they will receive final approval from the U.S. Food and Drug Administration or equivalent foreign regulatory agencies and for which indications; whether chimeric antigen receptor T cell (CAR T) approaches, Ad-RTS-hIL-12, TCR and NK

cell-based therapies, and our other therapeutic products will be successfully marketed if approved; the strength and enforceability of our intellectual property rights; competition from other pharmaceutical and biotechnology companies; and the other

risk factors contained in our periodic and interim SEC reports filed from time to time with the Securities and Exchange Commission, including but not limited to, our Annual Report on Form 10-K for the fiscal year ended December 31, 2015, and

our Quarterly Report for the quarter ended March 31, 2016. Readers are cautioned not to place undue reliance on these forward-looking statements that speak only as of the date hereof, and we do not undertake any obligation to revise and

disseminate forward-looking statements to reflect events or circumstances after the date hereof, or to reflect the occurrence of or non-occurrence of any events.

RheoSwitch Therapeutic System (RTS ) technology is a registered trademark of Intrexon Corporation.

Lori Ann Occhiogrosso

ZIOPHARM Oncology, Inc.