Oncothyreon Initiates Phase 1 Trial of PX-866 Cancer Compound

BELLEVUE, WA, June 17 /PRNewswire-FirstCall/ - Oncothyreon Inc. today announced enrollment of the first patient in a Phase 1 trial of PX-866 in patients with advanced solid tumors. PX-866 is a small molecule compound designed to inhibit the activity of phosphatidylinositol-3-kinase (PI-3K), an important cell survival signaling pathway.

“PX-866 is a potent inhibitor of PI-3K, a component of a critical pathway that is activated in many types of cancer, leading to tumor growth and survival,” said Lynn Kirkpatrick, Ph.D., Chief Scientific Officer of Oncothyreon. “We believe that the mechanism of action of PX-866, which irreversibly inhibits PI-3K, will have pharmacokinetic and pharmacodynamic advantages that will distinguish PX-866 in the competitive field of PI-3K inhibitors.”

The Phase 1 trial is expected to enroll up to 63 patients with advanced metastatic cancer who have failed or are intolerant of standard therapy. Patients will receive PX-866 orally once per day on days 1 through 5 and 8 through 12 during a four-week treatment cycle. Primary objectives of the study include establishment of a maximum tolerated dose, evaluation of safety, and analysis of the pharmacodynamic and pharmacokinetic profiles of PX-866.

“The start of the PX-866 trial represents a significant milestone for Oncothyreon, as we now have three active clinical programs underway for our promising small molecule inhibitors,” said Robert L. Kirkman, M.D., President and CEO of Oncothyreon. “Together with our therapeutic vaccine programs, we have successfully established a broad and diverse oncology pipeline targeting multiple cancer indications with substantial unmet medical need, and we look forward to sharing the ongoing progress from these clinical programs with the medical community and our investors.”

In addition to the PX-866 trial, Oncothyreon is conducting a Phase 2 trial of PX-12, an inhibitor of thioredoxin-1, in advanced pancreatic cancer, a Phase 1b trial of PX-12 in advanced metastatic cancer, and a Phase 1 trial of PX-478, a small molecule inhibitor of hypoxia inducible factor-1 alpha, in patients with advanced solid tumors or lymphomas. Oncothyreon’s partner, Merck KGaA of Darmstadt, Germany, is conducting a Phase 3 trial of Stimuvax(R), an investigational therapeutic cancer vaccine, in patients with stage III non-small cell lung cancer.

About PX-866

PX-866 is an inhibitor of the PI-3-kinase/PTEN/AKT pathway, an important survival signaling pathway that is activated in many types of human cancer. Aberrant activation and regulation of PI-3 kinase is implicated in a large proportion of human cancers including breast, glioma, colon, ovarian, prostate and melanoma, where it leads to increased proliferation and inhibition of apoptosis (programmed cell death). PX-866 has been shown to induce prolonged inhibition of tumor PI-3 kinase signaling following both oral and intravenous administration. The compound has been shown to have anti-tumor activity both as a single agent and in combination with other agents in a number of human tumor models.

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 clinical development plans for PX-866. 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, and the safety and efficacy of PX-866. There can be no guarantee that the results of preclinical studies or of early 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.

CONTACT: Investor and Media Relations Contact: Julie Rathbun, Rathbun
Communications, (206) 769-9219, ir@oncothyreon.com

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