ZIOPHARM Reports Fourth-Quarter and Full-Year 2013 Financial Results and Reviews Recent Activities BOSTON, MA

ZIOPHARM Reports Fourth-Quarter and Full-Year 2013 Financial Results and Reviews Recent Activities

BOSTON, MA March 3, 2014 ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP) today announced financial results for the fourth quarter and

full year ended December 31, 2013 and provided an update on the company s product development activities.

Working with our partner

Intrexon Corporation, we made extensive progress in 2013 toward expanding, and demonstrating the transformative potential of, what is a game-changing technology platform, said Jonathan Lewis, M.D., Ph.D., chief executive officer of ZIOPHARM.

This progress will continue in 2014, where we expect to achieve clinical milestones with lead candidate Ad-RTS-IL-12, continue to advance several, cutting edge new product candidates to the clinic, and potentially secure key

Corporate Highlights

is advancing a number of clinical- and preclinical-stage, gene based therapies and related technologies to allow precise regulation of protein expression and control of cellular function. Controlled expression and delivery of DNA and therapeutic

proteins is achieved through Intrexon Corporation s (NYSE: XON) RheoSwitch Therapeutic System (RTS ) technology, the most

advanced clinical method for precisely modulating protein production in gene based therapies.

ZIOPHARM recently presented results, including at the 2013

AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, demonstrating the use of both monogenic and multigenic systems and therapies in various cancer models, targeting cancer cell signaling pathways and the stimulation

of immune response to cancer. These data also highlighted the potential for gene delivery via multiple platforms, including viral vectors, mesenchymal stem cells and embedded cellular bioreactors.

For Ad-RTS-IL-12, a Phase 2, novel gene expression platform for the immune system cytokine interleukin-12,

ZIOPHARM and its academic collaborators have presented clinical and preclinical results demonstrating:

ZIOPHARM is currently conducting or planning Phase 2 studies of Ad-RTS-IL-12, alone or in combination with existing treatment standards, in melanoma and

breast cancer, with plans to initiate a Phase 1 study in high-grade gliomas (brain cancer). The Company also expects to file several investigational new drug (IND) applications for novel, multigenic gene therapies through 2015.

Fourth-Quarter 2013 Financial Results

Full Year 2013 Financial Results

About ZIOPHARM Oncology, Inc.:

ZIOPHARM Oncology is a

Boston, Massachusetts-based biotechnology company employing novel gene expression and control technology to deliver DNA for the treatment of cancer. ZIOPHARM s technology platform employs Intrexon Corporation s RheoSwitch Therapeutic

System technology to turn on and off, and precisely modulate, gene expression at the cancer site in order to improve the therapeutic index. This technology is currently being evaluated in

Phase 2 clinical studies of the immune system cytokine interleukin-12 for the treatment of breast cancer and advanced melanoma. Multiple new Investigational New Drug applications for new targets using synthetic biology technology are expected

through 2015. ZIOPHARM is also developing novel small molecules as potential cancer therapeutics.

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. Words such as expect(s), feel(s),

believe(s), will, may, anticipate(s) and similar expressions are intended to identify forward-looking statements. These statements include, but are not limited to, statements regarding our ability to

successfully develop and commercialize our therapeutic products; our ability to expand our long-term business opportunities; financial projections and estimates and their underlying assumptions; and future performance. 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 or projected by, the

forward-looking information and statements. These risks and uncertainties include, but are not limited to: whether Ad-RTS-IL-12,

palifosfamide, darinaparsin, indibulin, or any of our other therapeutic products will advance further in the 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 Ad-RTS-IL-12, palifosfamide, darinaparsin, indibulin, and our other therapeutic products will be successfully marketed

if approved; whether any of our other therapeutic product discovery and development efforts will be successful; our ability to achieve the results contemplated by our collaboration agreements; the strength and enforceability of our intellectual

property rights; competition from other pharmaceutical and biotechnology companies; the development of, and our ability to take advantage of, the market for our therapeutic products; our ability to raise additional capital to fund our operations on

terms acceptable to us; general economic conditions; 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, 2013. 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.

ZIOPHARM Oncology, Inc.

Condensed Statements of Operations

(in thousands except share and per share data)

ZIOPHARM Oncology, Inc.

Lori Ann Cafarella-Occhiogrosso