Oncothyreon Initiates Phase 1/2 Trial of its PI-3 Kinase Inhibitor PX-866 in Combination with Cetuximab

December 20, 2010

SEATTLE, WA, Dec. 20 /PRNewswire-FirstCall/ – Oncothyreon Inc. (Nasdaq: ONTY) today
announced enrollment of the first patient in a Phase 1/2 trial of
PX-866 in combination with the chimeric monoclonal antibody cetuximab
(Erbitux(R)). PX-866 is a small molecule compound designed to inhibit the
activity of phosphatidylinositol-3-kinase (PI-3K), a component of an
important cell survival signaling pathway.

The primary objective of the Phase 1 dose-escalation portion of the
trial is to determine the maximum tolerated or recommended daily dose
of PX-866 to be given in combination with the standard dose of
cetuximab administered weekly to patients with either progressive
metastatic colorectal carcinoma (CRC) or progressive, recurrent or
metastatic squamous cell carcinoma of the head and neck (SCCHN). The
Phase 2 portion is designed as a screening trial and will be an
open-label, randomized evaluation of the antitumor activity and safety
of PX-866 administered at the maximum tolerated or recommended dose in
combination with cetuximab, versus cetuximab alone, in two groups of
patients not previously treated with cetuximab.  Group 1 will enroll
patients with metastatic CRC who have a history of progression or
recurrence following prior treatment with irinotecan and oxaliplatin
containing regimens or who are intolerant of irinotecan.  Patients with
CRC and Kras mutations are excluded from the trial. Group 2 will enroll
patients with progressive, recurrent or metastatic SCCHN. The two
groups will be randomized and evaluated independently.

The primary endpoint of the Phase 1 portion of the trial is safety, and
will enroll up to a total of 18 patients at three different dose levels
of PX-866 in combination with cetuximab.  Up to 144 patients may be
enrolled in the Phase 2 portion of the study, including 72 (36 per arm)
in each group. The primary endpoint of the Phase 2 portion is objective
response rate based on RECIST criteria. Secondary endpoints include
progression free and overall survival, duration of response and disease
control rate. Additional information is available through

“We are delighted to have initiated this second of four planned Phase
1/2 and Phase 2 trials of PX-866,” said Robert L. Kirkman, M.D.,
President and CEO of Oncothyreon. “As previously indicated, we are
committed to a broad Phase 2 development program for PX-866, in
combination with other agents, as a single agent, and in multiple tumor
types, to maximize our opportunity to demonstrate the utility of this
novel, irreversible PI-3K inhibitor.”

About PX-866

PX-866 is an 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 presented at the American
Society of Clinical Oncology earlier this year 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.

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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