ZIOPHARM Terminates Development of Palifosfamide in Metastatic Soft Tissue Sarcoma

ZIOPHARM Terminates Development of Palifosfamide in Metastatic Soft Tissue
Sarcoma

Restructuring to Place Exclusive Strategic Focus on Synthetic Biology Programs

     Company to Host Conference Call Today, March 26, 2013 at 8:30 AM ET

NEW YORK, March 26, 2013 (GLOBE NEWSWIRE) -- ZIOPHARM Oncology, Inc.
(Nasdaq:ZIOP), a biopharmaceutical company focused on the development and
commercialization of new cancer therapies, announced today that its Phase 3
trial of palifosfamide (ZIO-201) for the treatment of metastatic soft tissue
sarcoma in the first-line setting (PICASSO 3) did not meet its primary
endpoint of progression-free survival (PFS). The study's independent data
monitoring committee (IDMC) has recommended that patients be followed for
overall survival (OS), the study's secondary endpoint, however the Company
does not expect to continue follow up for OS.Palifosfamide was well
tolerated, with a safety profile in combination with doxorubicin observed in
the study comparable with other palifosfamide clinical trials in soft tissue
sarcoma.Full data from PICASSO 3 will be submitted for publication in a
scientific journal.

With this outcome, ZIOPHARM has made the decision to immediately place
exclusive strategic focus on its synthetic biology programs, which are being
developed in partnership with Intrexon Corporation. The lead therapeutic
candidate in this program is Ad-RTS IL-12, a DNA therapeutic to enable
controlled delivery of therapeutic interleukin-12 (IL-12), a protein important
for an immune response to 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.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.

A highly focused team within the Company will be deployed in support of these
programs. As a result, a restructuring plan is immediately being put into
place to align staffing to current objectives and to marshal its resources
toward achieving success with its synthetic biology programs.

"We are disappointed that the PICASSO 3 study did not meet its primary
endpoint of progression-free survival," said Jonathan Lewis, M.D., Ph.D.,
Chief Executive Officer of ZIOPHARM."We sincerely thank the trial
investigators, clinical sites and the ZIOPHARM team for conducting a highly
rigorous study, and are deeply appreciative to the cancer patients and their
families for their participation in this trial."

Dr. Lewis added: "It is imperative that the Company rapidly focus its
resources and efforts on our highly promising synthetic biology programs,
employing therapeutic motifs that represent the next-generation in
biotechnology."

Conference Call and Webcast March 26, 2013, at 8:30 AM ET

ZIOPHARM will host a conference call and live audio webcast today, March 26,
2013, at 8:30 AM ET to discuss the PICASSO 3 trial.The call can be accessed
by dialing (877) 303-9850 (U.S. and Canada) or (408) 427-3732
(international).The passcode for the conference call is 'ZIOPHARM.'To access
the live audio webcast, or the subsequent archived recording, visit the
"Investors - Events & Presentations" section of the ZIOPHARM website at
www.ziopharm.com. The webcast will be recorded and available for replay on the
Company's website for two (2) weeks.

About PICASSO 3

The PICASSO 3 trial is an international, randomized, double-blinded,
placebo-controlled study. A total of 447 patients with metastatic soft tissue
sarcoma were randomized to receive either intravenous palifosfamide plus
doxorubicin (150 mg/m^2 3 days every 21 days for a maximum of 6 cycles
followed by 75 mg/m^2 1 day every 21 days for a maximum of 6 cycles) or
doxorubicin alone (75 mg/m^2 1 day every 21 days for a maximum of 6
cycles).The primary endpoint for the study is improvement in PFS, with
overall survival as a key secondary endpoint.Other secondary endpoints
include quality of life assessments, and the safety and tolerability of this
combination in this patient population.PICASSO 3 was conducted at more than
150 clinical centers in North America, Europe, South America, Australia,
Israel and Asia.

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:

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
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 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.

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.

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.

Forward-Looking Safe Harbor Statement:

This press release contains certain forward-looking information about ZIOPHARM
Oncology 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 Palifosfamide, Ad-RTS
IL-12, 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 Palifosfamide, Ad-RTS IL-12, 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 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, 2012. 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.

CONTACT: For ZIOPHARM
         Nicole Jones
         ZIOPHARM Oncology, Inc.
         617-778-2266
         njones@ziopharm.com
        
         Media Contacts:
         David Schull or Lena Evans
         Russo Partners, LLC
         858-717-2310
         212-845-4262
         david.schull@russopartnersllc.com
         lena.evans@russopartnersllc.com

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