New Nexavar Data Presented in Multiple Tumor Types at 44th American Society of Clinical Oncology Annual Meeting

Wayne, NJ and Emeryville, CA — Jun. 02, 2008

Bayer HealthCare Pharmaceuticals, Inc. and Onyx Pharmaceuticals, Inc. (Nasdaq: ONXX) today announced the presentation of new clinical data from the early clinical trials in the development program for Nexavar® (sorafenib) tablets in multiple tumor types including lung, thyroid, gastric and ovarian cancers. Nexavar is currently approved in more than 40 countries for the treatment of patients with unresectable liver cancer and in more than 70 countries for the treatment of patients with advanced kidney cancer.

“Findings from these early phase studies are encouraging and will be integral in informing our development strategies for the ongoing Nexavar clinical program,” said Henry Fuchs, MD, executive vice president and chief medical officer of Onyx Pharmaceuticals. “We are committed to maximizing the potential of Nexavar and look forward to its ongoing study with international study groups, government agencies and individual investigators in a wide range of cancers.”

Highlights from Nexavar data presented include:

Lung Cancer
A Randomized, Discontinuation Phase 2 Study of Sorafenib vs. Placebo in Patients with Non-Small Cell Lung Cancer (NSCLC) Who Have Failed at Least Two Prior Chemotherapy Regimens
Preliminary findings from this randomized discontinuation Phase 2 study showed that treatment with Nexavar yielded encouraging results in heavily pre-treated patients with NSCLC. The study showed that patients who remained on Nexavar experienced a longer period of disease control and disease stabilization than patients who discontinued Nexavar after the initial run-in phase of treatment. In the study, the most common treatment-emergent adverse events included fatigue, hand/foot syndrome and skin rash..

The lead investigator for this study is Joan Schiller, MD, professor and chief of the hematology/oncology division at the University of Texas Southwestern and Andrea L. Simmons distinguished chair in cancer research, Dallas, TX. (abstract #8014).

Thyroid Cancer
A Phase 2 Study of Sorafenib in Metastatic Thyroid Carcinoma
Findings from this single-arm Phase 2 study showed that treatment with Nexavar resulted in meaningful anti-tumor activity in the majority of patients with encouraging overall clinical benefit (disease stabilization and partial responses) in patients with advanced thyroid cancer. In the study, Nexavar was well-tolerated; the most common treatment-related adverse events included fatigue, rash, diarrhea, palmer-plantar erythema, musculoskeletal pain and weight loss. Patients enrolled in this study had been diagnosed with metastatic, iodine-refractory, unresectable or locally-advanced thyroid cancer.

The lead investigator for this study is Marcia S. Brose, MD, PhD, assistant professor, director of cancer genetics laboratory, University of Pennsylvania Health System, Philadelphia, PA. (abstract #6026).

Gastrointestinal Stromal Tumors
Activity of Sorafenib in Patients with Imatinib and Sunitinib-Resistant Gastrointestinal Stromal Tumors (GIST): A Phase 2 Trial of the University of Chicago Phase 2 Consortium
Findings from this single-arm Phase 2 study suggest that Nexavar is active and well tolerated in patients with Gleevec or Gleevec and Sutent resistant GIST. The most common treatment-emergent adverse events included hand-foot syndrome, hypertension, rash and diarrhea.

The lead investigator for this study is Lauren Wiebe, MD, fellow, University of Chicago, Chicago, IL. (abstract #10502).

A Phase 2 Study: Combination of Sorafenib with Docetaxel and Cisplatin in the Treatment of Metastatic or Advanced Unresectable Gastric and Gastroesophageal Junction (GEJ) Adenocarcinoma (ECOG 5203)
Findings from this single-arm Phase 2 study provide encouraging data for the potential use of Nexavar in combination with docetaxel and cisplatin to treat patients with metastatic/advanced gastric/GEJ adenocarcinoma. The most common treatment-emergent adverse events included neutropenia, fatigue, anorexia, hand-foot reaction, nausea, diarrhea and dehydration.

The lead investigator for this study is Weijing Sun, MD, assistant professor of medicine, University of Pennsylvania, director of the Upper GI and Pancreatic-Biliary-Hepatic Cancer Group and the associate director of the GI Cancer Program. (abstract #4535).

Phase 2 Trial of Sorafenib in Persistent or Recurrent Epithelial Ovarian Cancer or Primary Peritoneal Cancer: A Gynecologic Oncology Group Study
Preliminary findings from this Phase 2 study suggest that Nexavar is active and tolerated in patients with recurrent epithelial ovarian cancer. The most common treatment-emergent adverse events were dermatologic and metabolic.

The lead investigator for this study is Daniela Matei, M.D., Ph.D., assistant professor, department of medicine, Walther Oncology Center, Indiana University, Bloomington, IN. (abstract #5537).

“We continue to be encouraged by Nexavar’s potential activity as a single agent or in combination with other chemotherapeutic agents in these early stage clinical trials in tumor types with high unmet treatment needs,” said Susan Kelley, MD, vice president, Therapeutic Area Oncology, Bayer HealthCare Pharmaceuticals. “The more data we compile from various studies in multiple tumor types, the better informed we are to determine the appropriate direction for further development of Nexavar in additional clinical cancer settings.”

Nexavar’s Differentiated Mechanism
Nexavar targets both the tumor cell and tumor vasculature. In preclinical studies, Nexavar has been shown to target members of two classes of kinases known to be involved in both cell proliferation (growth) and angiogenesis (blood supply) - two important processes that enable cancer growth. These kinases included Raf kinase, VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-B, KIT, FLT-3 and RET.

Nexavar is also being evaluated by the companies, international study groups, government agencies and individual investigators as a single agent or combination treatment in a wide range of cancers, including metastatic melanoma, lung cancer, breast cancer and as an adjuvant therapy for kidney cancer.

Important Safety Considerations For Patients Taking Nexavar
Based on the currently approved U.S. package insert for the treatment of patients with unresectable hepatocellular carcinoma and advanced kidney cancer, hypertension may occur early in the course of therapy and blood pressure should be monitored weekly during the first six weeks of therapy and treated as needed. In HCC patients, bleeding with a fatal outcome from any site was reported in 2.4% for Nexavar and 4% in placebo. The incidence of treatment-emergent cardiac ischemia/infarction was 2.7% for Nexavar vs. 1.3% for placebo. In RCC patients, incidence of bleeding regardless of causality was 15% for Nexavar vs. 8% for placebo and the incidence of treatment-emergent cardiac ischemia/infarction was 2.9% for Nexavar vs. 0.4% for placebo. Most common adverse events ³20% related to Nexavar for both HCC and RCC were fatigue, weight loss, rash/desquamation, hand-foot skin reaction, alopecia, diarrhea, nausea, and abdominal pain. Grade 3/4 adverse events in HCC and RCC patients, respectively, were 45% for Nexavar vs. 32% for placebo and 38% for Nexavar and 28% for placebo. Women of child-bearing potential should be advised to avoid becoming pregnant and advised against breast-feeding. In cases of any severe or persistent side effects, temporary treatment interruption, dose modification or permanent discontinuation should be considered.

About Bayer HealthCare Pharmaceuticals Inc.
Bayer HealthCare Pharmaceuticals Inc. is the U.S.-based pharmaceuticals unit of Bayer HealthCare LLC, a division of Bayer AG. One of the world’s leading, innovative companies in the healthcare and medical products industry, Bayer HealthCare combines the global activities of the Animal Health, Consumer Care, Diabetes Care, and Pharmaceuticals divisions. In the U.S., Bayer HealthCare Pharmaceuticals comprises the following business units: Women’s Healthcare, Diagnostic Imaging, Specialized Therapeutics, Hematology/Cardiology and Oncology. The company’s aim is to discover and manufacture products that will improve human health worldwide by diagnosing, preventing and treating diseases.

About Onyx Pharmaceuticals, Inc.
Onyx Pharmaceuticals, Inc. is a biopharmaceutical company committed to improving the lives of people with cancer. The company, in collaboration with Bayer HealthCare Pharmaceuticals, Inc., is developing and marketing Nexavar® (sorafenib) tablets, a small molecule drug. For more information about Onyx, visit the company’s website at

Forward-Looking Statements
This news release contains forward-looking statements based on current assumptions and forecasts made by Bayer Group management. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. These factors include those discussed in our annual and interim reports filed with the Frankfurt Stock Exchange. The company assumes no liability whatsoever to update these forward-looking statements or to conform them to future events or developments.

This news release also contains “forward-looking statements” of Onyx within the meaning of the federal securities laws. These forward-looking statements include without limitation, statements regarding the timing, progress and results of the clinical development, safety, regulatory processes, and commercialization efforts of Nexavar. These statements are subject to risks and uncertainties that could cause actual results and events to differ materially from those anticipated. Reference should be made to Onyx’s Annual Report on Form 10-K for the year ended December 31, 2007, filed with the Securities and Exchange Commission under the heading “Risk Factors” and Onyx’s 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, events, or circumstances after the date of this release except as required by law.

Nexavar® (sorafenib) tablets is a registered trademark of Bayer HealthCare Pharmaceuticals, Inc.

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