Tigris Pharmaceuticals Presents Results of Breast Cancer Research at AACR Annual Meeting

    BONITA SPRINGS, Fla., April 30 /PRNewswire/ -- Tigris Pharmaceuticals,
Inc., a privately held drug development company, announced that preclinical
data were presented on its novel molecule, AFP-464, during the recent AACR
100th Annual Meeting 2009 in Denver. "This research represents a
significant advancement in the treatment of Triple Negative Breast Cancer,
one of the most aggressive forms of invasive breast cancer," stated Edmundo
Muniz, M.D., Ph.D., President and Chief Executive Officer of Tigris.

    Sponsored by Tigris, the research was led by Angelika Burger, Ph.D.,
director of the Translational Research Laboratory at the Barbara Ann
Karmanos Cancer Institute and professor of Pharmacology at Wayne State
University School of Medicine in Detroit. The research found that the
luminal (ER-positive) and the triple negative (ER, PR, and HER-2 negative)
breast cancer cell lines with the basal A gene profile subtype were very
sensitive to AFP-464, while the triple negative cell lines with the basal B
subtype were not. However, when the latter was pre-treated with a histone
deacetylase inhibitor, such as the suberoylanilide hydroxamic acid (SAHA),
also known as vorinostat (Zolinza(R), Merck & Co. Inc.), the cells became
very sensitive to AFP-464. The mechanism in which this is achieved is
believed to be the de-silencing of ER expression by the histone deacetylase
inhibitor, followed by CYP1A1 induction and subsequent AFP metabolism into
active species that covalently bind to DNA in these cancer cells and cause
specific cell death.

    Dr. Burger said the findings offer particular hope to those women
battling triple-negative breast cancer. "We could now find a way to treat
every kind of invasive, metastatic breast cancer, the ER-positive and
ER-negative types with AFP-464," said Dr. Burger. "The synergism between
AFP-464 and vorinostat in the triple negative breast cancer cell lines is
very impressive."

    AFP464 is nearing completion of Phase I clinical testing at Jules
Bordet Institute in Belgium, Institut Gustav Roussy in Paris, Mayo Clinic
in Rochester, Minnesota, Karmanos Cancer Institute in Detroit and
University of Maryland Marlene and Stewart Greenebaum Cancer Center in
Baltimore. Tigris Pharmaceuticals expects to soon move to Phase II clinical
studies, including studies in triple-negative breast cancer patients with
the drug alone or in combination with vorinostat, depending on the
molecular gene profile subtypes of the patients. Triple-negative breast
cancer afflicts mostly young women under the age of 40 and is more
prevalent in the African-American and Hispanic community. About 182,460
women in the United States were diagnosed with invasive breast cancer in
2008, approximately 15-18% of which are triple negative, and about 40,480
will die from the disease, according to the American Cancer Society.

    "Patients with triple negative breast cancer do not benefit from
endocrine therapy or molecularly targeted therapy such as trastuzumab
because they lack the targets for these drugs," said Dr. Binh Nguyen, M.D.,
Ph.D., Chief Medical Officer of Tigris. "The potential of using molecular
gene profile to target the appropriate patient population that most likely
could benefit from the treatment with AFP-464 is the right direction in the
clinical development of this difficult to treat disease."

    About AFP-464

    AFP-464, a Lysol prodrug of aminoflavone (AF), undergoes rapid
conversion to AF by nonspecific plasma esterases. It has shown a unique
pattern of growth inhibitory activity in the NCI's 60 tumor cell line
screen, with breast, ovarian, lung and renal lines exhibiting particular
sensitivity. The mechanism of action of AF is believed to be that treatment
with AF results in translocation of the arylhydrocarbon receptor (AhR; a
transcriptional regulator of CYP1A1) from the cytoplasm to the nucleus, and
its subsequent interaction with the xenobiotic-response element (XRE)
sequence on the CYP1A1 promoter region, causing induction of CYP1A1
transcription. This enzyme expression converts AF to metabolites that are
covalently bound to DNA. This results in phosphorylation of p53 with
induction of the p53 downstream target p21Waf1/Cip1 and apotosis.

    About Tigris Pharmaceuticals, Inc.

    Tigris Pharmaceuticals, Inc. is a privately held biopharmaceutical
company that develops therapeutic technologies, using a translational
research approach, for use in oncology and other areas of unmet medical
need. Tigris' mission is to efficiently move its existing and future
technologies through the various stages of clinical development in order to
meet patients' needs for safe and effective treatments of human illnesses.

    About the Barbara Ann Karmanos Cancer Institute

    Located in mid-town Detroit, Michigan, the Barbara Ann Karmanos Cancer
Institute is one of 40 National Cancer Institute-designated comprehensive
cancer centers in the United States. Caring for more than 6,000 new
patients annually on a budget of $216 million, conducting more than 700
cancer-specific scientific investigation programs and clinical trials, the
Karmanos Cancer Institute is among the nation's best cancer centers.
Through the commitment of 1,000 staff, including nearly 300 faculty
members, and supported by thousands of volunteer and financial donors, the
Institute strives to prevent, detect and eradicate all forms of cancer. For
more information call 1-800-KARMANOS or go to http://www.karmanos.org.

    This news release contains forward-looking statements that involve
risks and uncertainties that could cause our actual results and experiences
to differ materially from anticipated results and expectations expressed in
such forward-looking statement. These forward-looking statements include,
without limitation, statements regarding the mechanism of action of
AFP-464, its potential advantages, its potential for use in treating
cancer, as well as the timing, progress and anticipated results of the
clinical development and regulatory processes concerning AFP-464. These
statements are based on our current beliefs and expectations as to such
future outcomes, and are subject to known and unknown risks and
uncertainties that may cause actual future experience and results to differ
materially from the statements made. Factors that might cause such a
material difference include, among others, risks that the results of
clinical trials will not support our claims or beliefs concerning the
effectiveness of AFP-464, our ability to finance our development of
AFP-464, regulatory risks, and our reliance on third party researchers and
other collaborators. We assume no obligation to update these statements,
except as required by law.