NEW YORK--(BUSINESS WIRE)--
ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP), a drug development company
employing small molecule and synthetic biology approaches to cancer
therapy, announced today new preclinical data from two separate studies
of darinaparsin (Zinapar® or ZIO-101), a novel organic
arsenic, in various solid tumor models at the AACR-NCI-EORTC
International Conference on Molecular Targets and Cancer Therapeutics,
taking place November 12-16 in San Francisco. Both studies were
conducted at the Stanford University School of Medicine by lead author,
Junqiang Tian, M.D., Ph.D., senior author, Susan J. Knox, M.D., Ph.D.,
from the Department of Radiation Oncology, and were performed in
collaboration with co-author, Donna Peehl, Ph.D., Professor of Urology.
In the first study, titled "Darinaparsin sensitizes solid tumors but not
normal tissues to radiation," human prostatic [hormone-independent (HI)
LAPC-4] and pancreatic [PANC-1] tumor models were treated with
darinaparsin (100 mg/kg) or saline (control), with the addition of local
tumor x-ray irradiation. Previous preclinical work at Stanford
established darinaparsin's cytotoxic and radiation enhancing modes of
action under both normoxic (NO) and hypoxic (HO) conditions in prostate
cancer, pancreatic cancer, cervical cancer, and glioblastoma cell lines.
Hypoxia is an important condition in the microenvironment of solid tumor
cells which creates resistance to cytotoxic drugs and radiation and
causes cancer stem cells to re-grow the tumor. This study was performed
to assess the effect of different radiation dosing regimens as well as
the potential radiosensitizing effect of darinaparsin on normal
radiosensitive intestine and bone marrow.
Intestinal crypt microcolony assay and blood cell counts were used to
assess the effect of darinaparsin on intestinal and bone marrow cell
radiosensitivity, respectively. In both the prostate and pancreatic
tumor models, a single dose of darinaparsin four hours before radiation
significantly enhanced radiation-induced tumor growth inhibition, with a
significant delay of tumor volume doubling time observed from 8.4 days
with radiation alone and 6.2 days with darinaparsin alone, to 14.7 days
for the combined treatment of radiation and darinaparsin.
Darinaparsin-mediated radiosensitization was observed in prostate tumors
with both single and fractionated irradiation dosing regimens.
Importantly, no systemic toxicity was observed with the darinaparsin
treatment alone, and darinaparsin did not sensitize normal intestinal
epithelium and bone marrow to the effect of radiation at the studied
dose.
"These results suggest that darinaparsin has the potential to sensitize
relatively radioresistant tumors without affecting normal tissues,"
commented senior author, Susan J. Knox. "They further suggest that
darinaparsin may increase the therapeutic index of radiation therapy
and, as was shown with our first study, have near-term translational
potential."
A second study, titled "Darinaparsin is an anti-solid tumor cytotoxin in
vivo," again evaluated prostate and pancreatic tumor models treated
with darinaparsin (100 mg/kg) or saline (control). In both the prostate
and pancreatic tumor models, darinaparsin significantly inhibited tumor
growth (p 0.0001), with the average tumor volume doubling time
increasing from 3.95 days to 11.8 days in the prostate tumor model, and
3.83 days to 6.82 days in the pancreatic tumor model. Importantly, no
significant systemic toxicities were exhibited at studied dose, as
assessed by organ histology and blood biochemistry.
Dr. Knox remarked: "Darinaparsin was found to have significant cytotoxic
activity in these two well-established solid tumor models, without
apparent systemic toxicity. With darinaparsin currently in clinical
development, these findings may have near-term translational potential."
About ZIOPHARM Oncology, Inc.:
ZIOPHARM Oncology is a biopharmaceutical company engaged in the
development and commercialization of a diverse portfolio of cancer
therapeutics. The Company's small molecule programs include:
Palifosfamide (Zymafos® or ZIO-201) is a novel DNA
cross-linker in class with bendamustine, ifosfamide, and
cyclophosphamide and is currently in a randomized, double-blinded,
placebo-controlled Phase 3 trial with palifosfamide administered
intravenously for the treatment of metastatic soft tissue sarcoma in the
front-line setting. The Company is also currently conducting a Phase 1
study of palifosfamide in combination with standard of care for
addressing small cell lung cancer; an oral form of palifosfamide
continues in preclinical study.
Darinaparsin (Zinapar® or ZIO-101) is a novel
mitochondrial-targeted agent (organic arsenic) currently in a solid
tumor Phase 1 study with oral administration and has been developed
intravenously for the treatment of relapsed peripheral T-cell lymphoma.
Indibulin (Zybulin™ or ZIO-301) is a novel, oral tubulin binding agent
that is expected to have several potential benefits including oral
dosing, application in multi-drug resistant tumors, no neuropathy and a
quite tolerable toxicity profile. It is currently being studied in Phase
1/2 in metastatic breast cancer.
ZIOPHARM is also pursuing the development of novel DNA-based
therapeutics in the field of cancer pursuant to a partnering arrangement
with Intrexon Corporation. The partnership includes two existing
clinical-stage product candidates, both of which are currently in Phase
1.
ZIOPHARM's principal operations are located in Boston, MA with an
executive office in New York City and a small satellite office in
Germantown, MD. Further information about ZIOPHARM may be found at www.ziopharm.com.
ZIOP-G
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, 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, Darinaparsin, Indibulin,
and our other therapeutic products will be successfully marketed if
approved; whether our DNA-based biotherapeutics 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 DNA-based biotherapeutics;
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 including but
not limited to our Annual Report on Form 10-K for the fiscal year ended
December 31, 2010, our Quarterly Report on Form 10-Q for the quarter
ended September 30, 2011, and our Current Reports on Form 8-K filed from
time to time with the Securities and Exchange Commission. 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.
For ZIOPHARM:
ZIOPHARM Oncology, Inc.
Tyler Cook,
617-259-1982
tcook@ziopharm.com
or
Media:
Argot
Partners
David Pitts, 212-600-1902
david@argotpartners.com
Source: ZIOPHARM Oncology, Inc.
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