Oncothyreon Presents Preclinical Data on Irreversible PI3 Kinase Inhibitor PX-866 at AACR Special Conference

SEATTLE, March 1 /PRNewswire-FirstCall/ - Oncothyreon Inc. (Nasdaq: ONTY) today announced the presentation of preclinical data on PX-866, its irreversible inhibitor of phosphatidylinositol 3-kinase (PI3K), at the American Association of Cancer Research (AACR) Special Conference "Targeting PI3K/mTOR Signaling."

PX-866 is an oral, small molecule compound designed to inhibit the activity of PI3K, a component of an important cell survival signaling pathway. Results presented at the meeting demonstrate that the primary metabolite of PX-866, 17-OH PX-866, has improved potency compared to the already potent parent compound against the alpha and beta isoforms of PI3K, as well as improved potency against forms of PI3K alpha that contain activating mutations. In addition, the effect of PX-866 and its metabolite as an irreversible PI3K inhibitor was demonstrated using biochemical and cellular assays.

"These data demonstrate that the primary metabolite of PX-866 is highly active against the alpha and beta isoforms of PI3K, which are important targets for the treatment of solid tumor cancers," said Scott Peterson, Ph.D., Vice President, Research & Development at Oncothyreon. "The promising pharmcodynamic and clinical effects demonstrated at low doses in Phase 1 evaluation further support the potential for this product candidate, and we look forward to sharing initial Phase 2 clinical data from our ongoing trials later this year."

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 squamous cell carcinoma of the head and neck (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 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.

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 circumstances.

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.