Oncothyreon Initiates Phase 1/2 Trial of PX-866 in Combination with Vemurafenib

SEATTLE, May 31, 2012 /PRNewswire/ - Oncothyreon Inc. (Nasdaq: ONTY) today announced the initiation of a Phase 1/2 trial of PX-866 in combination with vemurafenib (Zelboraf®).  PX-866 is Oncothyreon's investigational small molecule compound designed to inhibit the activity of phosphatidylinositol-3-kinase (PI-3K), a component of an important cell survival signaling pathway.  Vemurafenib is a kinase inhibitor indicated for the treatment of unresectable or metastatic melanoma with the BRAF^V600E mutation.

The Phase 1 portion of this trial will evaluate the safety and tolerability of PX-866 in combination with twice daily oral administration of vemurafenib in up to 36 patients with any BRAF-mutant cancer.  The trial will use a dose-escalation design to evaluate up to three dose levels of PX-866 with up to two dose levels of vemurafenib to determine the maximally tolerated or recommended dose of both PX-866 and vemurafenib to be used in Phase 2.  The Phase 2 portion of the trial will compare the anti-tumor activity and safety of PX-866 and vemurafenib at the doses recommended from Phase 1 with vemurafenib alone administered at the approved dose.  This randomized Phase 2 trial is expected to enroll 110 patients with advanced BRAF-mutant melanoma and has a primary endpoint of progression-free survival.

This Phase 1/2 trial is being conducted in collaboration with the Melanoma Research Foundation Breakthrough Consortium (MRFBC).  Lynn M. Schuchter, M.D., Chief of the Hematology Oncology Division and leader of the melanoma program at the Abramson Cancer Center of the University of Pennsylvania, a member of the MRFBC, said, "While vemurafenib has significantly prolonged the lives of patients with BRAF-mutant melanoma, many patients develop resistance.  Preclinical evidence suggests that the PI-3 kinase pathway may contribute to this resistance, and we are therefore excited to begin this study."

"We are grateful to the MRFBC for proposing and performing this study," said Robert L. Kirkman, M.D., President and Chief Executive Officer of Oncothyreon.  "With the initiation of this trial, Oncothyreon is now conducting five Phase 2 trials of PX-866 in six different tumor types, a broad development program reflecting our enthusiasm for this product candidate."

About the Melanoma Research Foundation Breakthrough Consortium

The mission of the Melanoma Research Foundation Breakthrough Consortium (MRFBC) is to accelerate research and development of the most promising therapeutics in melanoma to deliver curative treatment options to patients.  The Consortium was created in 2010 and consists of basic scientists, translational researchers and investigators from 13 centers of excellence in melanoma, including all of the centers designated by National Cancer Institute as a Specialized Program of Research Excellence (SPORE) in skin cancer.  The MRFBC works through collaborative private, public and nonprofit partnerships to facilitate, conduct or enhance the development of the most promising combination therapies - a strategy which has been shown to be the cornerstone of success in treating diseases such as TB and HIV.  In addition to support of high-impact clinical trials, key initiatives include preclinical testing of compounds in combination, development of a collaborative virtual specimen bank operating under common standards, and development of a translational research agenda across trials.  Clinical trials supported by the MRFBC are opening this year.

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).

Oncothyreon is conducting a broad development program of PX-866 as a single agent and in combination with other agents in multiple cancer types. In addition to the above trial, current trials include a Phase 1/2 trial of PX-866 in combination with cetuximab (Erbitux®) in patients with metastatic colorectal carcinoma 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 locally advanced, recurrent or metastatic non-small cell lung cancer or SCCHN. In addition, the NCIC Clinical Trials Group is conducting two Phase 2 trials, one in patients with recurrent or metastatic castration- resistant prostate cancer and one in patients with glioblastoma multiforme that has recurred during or following primary therapy.

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 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.