Press

Release

NEW HAVEN, CT April 19, 2005 - ZIOPHARM, Inc. announced today Dr. Lee Roy Morgan presented the preclinical pharmacology and toxicology data for ZIO-201 (L-IPM , or lysine-isophosphoramide mustard) at the American Association for Cancer Research (AACR) meeting in Anaheim, California. ZIO-201 is the Company's proprietary alkylating drug and the active metabolite of ifosfamide.

Pharmaceutical formulation instability previously precluded clinical development of isophosphoramide mustard. L-IPM is a proprietary, stabilized pharmaceutical preparation now in a phase I trial. Data presented today include L-IPM activity in cyclophosphamide- and ifosfamide-resistant cancers. L-IPM, unlike ifosfamide, is not metabolized to acrolein or acetaldehydes: preclinical studies show no central nervous system, kidney or bladder toxicities.

"The ability to give high doses of L-IPM, particularly in cyclophosphamide- and ifosfamide-resistant cancers, may considerably broaden ZIO-201's therapeutic range," commented Robert Peter Gale, MD, PhD, Chief Scientific Officer of ZIOPHARM. "Furthermore, because ZIO-201 is directly active there are no metabolites to cause the typical toxicities of cyclophosphamide and ifosfamide."

About ZIOPHARM, Inc.

ZIOPHARM is a privately held company that commenced operations in January 2004 to develop and commercialize a diverse, risk-sensitive portfolio of in-licensed cancer therapies. All products are focused on addressing unmet medical needs, with the potential for expedited regulatory approval and broad usage.

The Company's first in-licensed product in August of 2004, ZIO-101 or organic arsenic, is a small molecule from The University of Texas M.D. Anderson Cancer Center and Texas A&M University. A second organic arsenic from that broad licensing arrangement, ZIO-102, is expected to undergo further preclinical study this year as ZIO-101 progresses through phase I study in both hematologic and solid tumor cancers. A phase I/II trial of ZIO-101 is anticipated to begin in the second half of this year.

ZIO-201, or proprietary IPM (isophosphoramide mustard), is a small molecule licensed in November of 2004 from DEKK-Tec of New Orleans and is currently in phase I study in patients with late-stage cancers at the Karmanos Cancer Center in Detroit. A phase I/II trial is expected to initiate in the second half of this year. As announced in January 2005, the Company is conducting preclinical research with IPM analogs in collaboration with Southern Research Institute under its Collaboration and Option Agreement with the objective of establishing a ZIO-202 clinical candidate.

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 the Company's 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.

Contact:

Dr. Jonathan Lewis
Chief Executive Officer
203 848 3400