Oncothyreon Presents Preclinical Data for ONT-10 and PX-866 at American Association for Cancer Research

April 4, 2011

SEATTLE, WA, April 4 /PRNewswire-FirstCall/ – Oncothyreon Inc. (Nasdaq: ONTY) today
announced the presentation of preclinical data for ONT-10, a
therapeutic vaccine directed at cancers expressing MUC1, and PX-866,
its irreversible inhibitor of phosphatidylinositol 3-kinase (PI3K), at
the American Association of Cancer Research meeting in Orlando,


ONT-10 is a therapeutic vaccine targeting MUC1 which has been designed
to stimulate both the humoral and cellular arms of the immune
response.  Results presented at the meeting demonstrated that
administration of ONT-10 produced a robust antibody response in mice
that was specific for human tumor MUC1.  A strong cellular immune
response directed to the target was also shown.  ONT-10 blocked the
growth of two different tumors expressing human MUC1 in murine models,
with a high proportion of animals tumor free at the conclusion of the
experiment.  Additionally, the adjuvant component of ONT-10, PET-Lipid
A, a fully synthetic toll like receptor 4 (TLR4) agonist discovered by
Oncothyreon, was shown to have enhanced potency compared to the
adjuvant monophosphoryl lipid A (MPL).

“These preclinical data validate our hypothesis that the antigen present
in ONT-10 stimulates both effector arms of the immune response,” said
Scott Peterson, Ph.D., Vice President of Research and Development at
Oncothyreon.  “We are looking forward to beginning our first clinical
trial with ONT-10 late this year with a goal of replicating these data
in man.”


PX-866 is an oral, small molecule compound designed to inhibit the
activity of PI3K, a component of an important cell survival signaling
pathway. Data presented at the meeting concerned the efficacy of PX-866
alone or in combination with either docetaxel or cetuximab in direct
patient human tumor xenograft models (DPTM) of squamous cell carcinoma
of the head and neck (SCCHN) developed by Dr. Antonio Jimeno’s
laboratory at University of Colorado School of Medicine.  These models
maintain the histology of the tumor and are particularly suited to
preclinical evaluation of novel cancer therapeutics.  PX-866 was equal
or superior to docetaxel in slowing tumor growth in two of four DPTM
and equal or superior to cetuximab in each of four DPTM. The
combination of PX-866 plus docetaxel was superior to single agent
therapy in three of four DPTM, while the combination with cetuximab was
superior to single agent therapy in two of four DPTM.  The data were
presented by Daniel W. Bowles, M.D., University of Colorado School of
Medicine, Aurora, Colorado.

“These data are strongly supportive of our ongoing Phase 1/2 trials of
PX-866 in combination with either docetaxel or cetuximab,” said Diana
Hausman, M.D., Vice President of Clinical Development at Oncothyreon.
“The Phase 2 portion of each of these trials includes an arm enrolling
patients with SCCHN.”

About ONT-10

ONT-10 is a therapeutic vaccine targeting MUC1, a tumor-associated
antigen present on many types of human malignant tumors, including
lung, breast, colorectal, prostate and ovarian cancer.  ONT-10 contains
a forty three amino acid antigen which is glycosylated; the attached
sugars are expected to contribute to the stimulation of an immune
response to the vaccine.  The adjuvant in ONT-10 is PET Lipid A, a
fully synthetic TLR4 agonist developed at Oncothyreon.  Oncothyreon
currently expects to file an Investigational New Drug application for
ONT-10 in the third quarter of 2011 and to begin a Phase 1 clinical
trial by late 2011.  ONT-10 and PET Lipid A are fully owned by

About PX-866

PX-866 is a pan inhibitor of the PI-3K/PTEN/AKT pathway, a critical cell
signaling pathway that is activated in many types of human cancer.
Aberrant activation and regulation of PI-3K is implicated in a large
proportion of human cancers, where it leads to increased proliferation
and inhibition of apoptosis (programmed cell death). Results from a
single-agent Phase 1 open-label, dose escalation study of PX-866 in
patients with advanced metastatic cancer demonstrated that PX-866 was
well tolerated using both an intermittent and continuous (daily) dosing
schedule.   Additional data from the Phase 1 trial presented at the
EORTC/NCI/AACR meeting in Berlin on November 18, 2010 demonstrated that
8 of 19 evaluable patients treated with continuous dosing achieved
stable disease as their best response.

Oncothyreon is conducting a broad development program of PX-866
including clinical trials evaluating the compound as a single agent and
in combination with other agents in multiple cancer types. Current
trials include a Phase 1/2 trial of PX-866 in combination with
cetuximab (Erbitux®) in patients with progressive metastatic colorectal
carcinoma (CRC) or progressive, recurrent or metastatic SCCHN and a
Phase 1/2 trial of PX-866 in combination with the chemotherapeutic
agent docetaxel in patients with advanced cancers for which docetaxel
is considered standard of care.  In addition, the National Institute of
Canada Clinical Trials Group is expected to initiate two Phase 2 trials
of PX-866, one in patients with castration-resistant prostate cancer
and the second in patients with relapsed glioblastoma.

About Oncothyreon

Oncothyreon is a biotechnology company specializing in the development
of innovative therapeutic products for the treatment of cancer.
Oncothyreon’s goal is to develop and commercialize novel synthetic
vaccines and targeted small molecules that have the potential to
improve the lives and outcomes of cancer patients. For more
information, visit www.oncothyreon.com.

Forward Looking Statements

In order to provide Oncothyreon’s investors with an understanding of its
current intentions and future prospects, this release contains
statements that are forward looking, including statements related to
future preclinical and clinical development plans for our product
candidates. These forward-looking statements represent Oncothyreon’s
intentions, plans, expectations and beliefs and are based on its
management’s experience and assessment of historical and future trends
and the application of key assumptions relating to future events and

Forward-looking statements involve risks and uncertainties, including
risks and uncertainties related to Oncothyreon’s business and the
general economic environment. Many of these risks and uncertainties are
beyond Oncothyreon’s control. These risks, uncertainties and other
factors could cause our actual results to differ materially from those
projected in forward-looking statements. Risks, uncertainties, and
assumptions include those predicting the timing, duration and results
of clinical trials, the timing and results of regulatory reviews, the
safety and efficacy of our product candidates, and the indications for
which our product candidates might be developed. There can be no
guarantee that the results of preclinical studies or clinical trials
will be predictive of either safety or efficacy in future clinical
trials. These and other risks and uncertainties are described in the
reports and other documents filed by Oncothyreon Inc. with the SEC
and/or Canadian regulatory authorities.

Although Oncothyreon believes that any forward-looking statements
contained herein are reasonable, it can give no assurance that its
expectations are correct. All forward-looking statements are expressly
qualified in their entirety by this cautionary statement. For a
detailed description of the risks and uncertainties associated with
Oncothyreon, you are encouraged to review the official corporate
documents filed with the securities regulators in the United States on
U.S. EDGAR and in Canada on SEDAR. Oncothyreon is under no obligation
to (and expressly disclaims any such obligation to) update or alter its
forward-looking statements whether as a result of new information,
future events, or otherwise.

SOURCE Oncothyreon Inc.

Source: newswire

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