Phase 3 Trial of Investigational Compound Regorafenib (BAY 73-4506) in Metastatic Gastrointestinal Stromal Tumors (GIST) Meets Primary Endpoint of Improving Progression-Free Survival

Phase 3 Trial of Investigational Compound Regorafenib (BAY 73-4506) in Metastatic Gastrointestinal Stromal Tumors (GIST) Meets Primary Endpoint of Improving Progression-Free Survival

SOUTH SAN FRANCISCO, Calif., April 3, 2012 /PRNewswire via COMTEX/ -- Onyx Pharmaceuticals, Inc. today announced results from the Phase 3 trial GRID (GIST - Regorafenib in Progressive Disease) evaluating the investigational compound regorafenib (BAY 73-4506), a Bayer-owned compound, for the treatment of patients with metastatic and/or unresectable gastrointestinal stromal tumors (GIST) whose disease has progressed despite prior treatment with at least imatinib and sunitinib. The trial met its primary endpoint of statistically significant improvement in progression-free survival. In this trial, the safety and tolerability of regorafenib were consistent with what was seen in earlier studies. Data from the study are expected to be presented at an upcoming scientific meeting. The GRID study was sponsored by Bayer with academic leadership from the principal investigator George Demetri, M.D., Director of the Ludwig Center at the Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, U.S.A. The study started in January 2011 and completed enrollment by July 2011.

"GIST is a difficult disease to treat. Patients treated with currently available therapies have a high likelihood that their disease will progress, and there are no remaining treatment options for those patients whose prior therapies have failed," said Ted W. Love, M.D., Executive Vice President, Research and Development and Technical Operations at Onyx Pharmaceuticals. "These clinical data will show regorafenib's activity in patients with previously treated GIST."

Bayer is in ongoing discussions with health authorities worldwide. The company has plans to file for U.S. approval of regorafenib in the treatment of metastatic GIST.

About the GRID Study GRID (GIST - Regorafenib In Progressive Disease) was a randomized, double-blind, placebo-controlled, multi-center, cross-over Phase III study of regorafenib for the treatment of GIST.(i) It enrolled 199 patients whose disease had progressed despite prior treatment with at least imatinib and sunitinib.(i)

Patients were randomized in a 2:1 ratio to receive either regorafenib (160 mg once daily, 3 weeks on/1 week off) plus best supportive care (BSC) or placebo plus BSC.(i) Subjects receiving placebo who experienced disease progression were offered regorafenib treatment.(i) The primary endpoint of this trial is progression-free survival, and secondary endpoints include overall survival, time to progression, disease control rate, tumor response rate, and duration of response.(i) In this trial, safety was also evaluated.(i)

About GISTGIST is the most common form of sarcoma (a type of cancer that develops from certain tissues, like bone or muscle) involving the gastrointestinal tract.(ii) Targeted therapy may be used to treat GIST tumors if the tumor cannot be surgically removed or to shrink it to become small enough to be removed by surgery.(iii) In the United States, it is estimated that there are approximately 4,000-5,000 new cases of GIST diagnosed each year.(iv) GIST may not cause any symptoms and may be found incidentally when the doctor is looking for other problems.(iv)

About RegorafenibRegorafenib is an investigational oral multi-kinase inhibitor of angiogenic, tumor microenvironment and oncogenic kinases and is currently being investigated in clinical trials for its potential to treat patients with various tumor types.

Regorafenib is an investigational agent and is not approved by the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA) or other health authorities.

Regorafenib is one of several cancer compounds in Bayer's development pipeline. In 2011, Bayer entered into an agreement with Onyx Pharmaceuticals, Inc., under which Onyx will receive a royalty on any future global net sales of regorafenib in oncology.

About Onyx Pharmaceuticals, Inc.Based in South San Francisco, California, Onyx Pharmaceuticals, Inc. is a global biopharmaceutical company engaged in the development and commercialization of innovative therapies for improving the lives of people with cancer and other serious diseases. The company is focused on developing novel medicines that target key molecular pathways. For more information about Onyx, visit the company's website at www.onyx.com .

Forward-Looking StatementsThis news release contains "forward-looking statements" of Onyx within the meaning of the federal securities laws. These forward-looking statements include, without limitation, statements regarding the clinical development, safety, and regulatory processes of regorafenib and its commercial potential. These statements are subject to risks and uncertainties that could cause actual results and events to differ materially from those anticipated, including risks related to the fact that Nexavar is Onyx's only approved product; regorafenib is not approved, may never receive marketing approval and may never generate royalties for Onyx; competition; failures or delays in clinical trials or the regulatory process; dependence on Onyx's collaborative relationship with Bayer; market acceptance and the rate of adoption of products; pharmaceutical pricing and reimbursement pressures; and serious adverse side effects, if they are associated with Nexavar, regorafenib or carfilzomib. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Reference should be made to Onyx's Annual Report on Form 10-K for the year ended December 31, 2011, filed with the Securities and Exchange Commission under the heading "Risk Factors" and Onyx's subsequent Quarterly Reports on Form 10-Q for a more detailed description of such factors. Readers are cautioned not to place undue reliance on these forward-looking statements that speak only as of the date of this release. Onyx undertakes no obligation to update publicly any forward-looking statements to reflect new information.

(i) Integrated Clinical Study Protocol. No. BAY 73-4506/14874. September 2011

(ii) Joensuu H. Gastrointestinal stromal tumor (GIST). Available on http://annonc.oxfordjournals.org/content/17/suppl_10/x280.full.pdf +html. Annals of Oncology 17 (Supplement 10). September 2006, Volume 17

(iii) National Cancer Institute Gastrointestinal Stromal Tumors Treatment. Available at http://www.cancer.gov/cancertopics/pdq/treatment/gist/Patient/page3 . Accessed March 14, 2012.

(iv) American Cancer Society Gastrointestinal Stromal Tumor (GIST) (Last Revised 2/1/2012). Available at http://www.cancer.org/acs/groups/cid/documents/webcontent/003103-pdf.pdf . Accessed March 14, 2012

SOURCE Onyx Pharmaceuticals, Inc.

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