Bayer and Onyx Announce Phase II Results of Treatment With BAY 43-9006 in Patients with Advanced Primary Liver Cancer

Bayer and Onyx Announce Phase II Results of Treatment With BAY
43-9006 in Patients with Advanced Primary Liver Cancer
52 Percent of Patients Experienced Disease Stabilization or Tumor
Shrinkage


WEST HAVEN, Conn., and RICHMOND, Calif., Sept. 29  /PRNewswire-FirstCall/ --
Bayer Pharmaceuticals Corporation (NYSE:BAY) and Onyx Pharmaceuticals, Inc.
(NASDAQ:ONXX) today announced results from a Phase II clinical trial of BAY
43-9006 administered as a single agent in patients with advanced hepatocellular
carcinoma (HCC), or liver cancer (hepatoma).  The data were presented at the
16th American Association for Cancer Research -- National Cancer Institute --
European Organization for Research and Treatment of Cancer (AACR-NCI-EORTC)
meeting in Geneva, Switzerland.

BAY 43-9006, a novel RAF kinase and VEGFR inhibitor under investigation for the
treatment of different types of cancer, combines two anticancer activities:
inhibition of tumor cell proliferation and angiogenesis (the growth of new
blood vessels).

"In this Phase II study of advanced primary liver cancer, 43 percent of
patients treated with BAY 43-9006 experienced stable disease for at least four
months and an additional nine percent of patients experienced tumor shrinkage,"
said Dr. Ghassan K. Abou-Alfa, lead investigator and clinical assistant
attending at the Memorial Sloan-Kettering Cancer Center, New York, U.S.A.  "As
we continue to evaluate BAY 43-9006, this clinical study offers a promising
step in the fight against primary liver cancer, a disease that has very limited
treatment options."

Of 137 patients enrolled in the study, investigators reported seven patients
with partial responses (tumor shrinkage of 50 percent or greater), five with
minor responses (tumor shrinkage of 25 to 50 percent) and 59 with stable
disease for at least four months as their best response.  Median overall
survival for all patients was 9.2 months and median time-to-tumor progression
(TTP) was 4.2 months.

In the study, safety data generated showed that BAY 43-9006 was well tolerated
and side effects were predictable and manageable.  The most common grade 3/4
drug-related toxicities were fatigue (9.5 percent), diarrhea (8 percent), and
hand-foot skin reaction (5 percent).

"More than 500,000 people worldwide succumb to hepatocellular carcinoma each
year. The disease is increasing in incidence rates and remains one of the most
difficult tumor types to treat.  We are encouraged by the signs of activity of
BAY 43-9006 in HCC patients enrolled in this study," said Susan Kelley, M.D.,
vice president, Oncology, Bayer Pharmaceuticals Corporation. "Based on these
preliminary data, we will be advancing the BAY 43-9006 clinical development
program in HCC and will be initiating a Phase III single-agent study as well as
a Phase II combination study with the chemotherapy agent doxorubicin."

Phase II Study Design

The BAY 43-9006 Phase II multi-center study enrolled 137 patients with
inoperable HCC who had received no prior systemic treatment, had Child-Pugh
score A or B (a measure of the severity of liver failure in cirrhosis) and an
Eastern Cooperative Oncology Group (ECOG) performance status less than or equal
to one.  Patients received oral BAY 43-9006 at 400 mg twice a day continuously
in four-week cycles.  The goal of the study was to assess time to response,
duration of response/stable disease, time to progression, overall survival and
safety.  Tumor response was assessed every eight weeks using World Health
Organization (WHO) criteria.

About BAY 43-9006

BAY 43-9006, a novel investigational drug candidate, has demonstrated
anti-proliferative and anti-angiogenic properties -- two important anticancer
activities.  In preclinical models, BAY 43-9006 inhibited tumor cell
proliferation by targeting the RAF/MEK/ERK signaling pathway at the level of
RAF kinase.  BAY 43-9006 also exerted an antiangiogenic effect by targeting the
receptor tyrosine kinases VEGFR-2 and PDGFR and their associated signaling
cascades.

BAY 43-9006 has shown anticancer activity in a number of tumor types.  It is
being evaluated both as a single agent therapy and in combination with
conventional chemotherapeutics in a number of ongoing clinical trials.  For
more information on BAY 43-9006 clinical trials, visit
http://www.clinicaltrials.gov/ .

About Hepatocellular Carcinoma

Hepatocellular carcinoma, also known as primary liver cancer, is the most
common form of liver cancer and is responsible for 80 percent of the primary
malignant liver tumors in adults.  It is the fifth most common cancer in the
world.  In 2000, approximately 564,000 HCC cases were reported worldwide, with
11,500 cases in the United States and 50,000 in Europe.  HCC is most prevalent
in developing countries, particularly in East and South-east Asia, the Pacific
Basin, and sub-Saharan Africa. Of the 564,000 cases worldwide approximately
271,500 were reported in Eastern Asia (with 221,000 in China and 33,000 in
Japan alone).  HCC causes more than 500,000 deaths annually worldwide.  The
five-year relative survival rate is about seven percent.

Additional BAY 43-9006 AACR-NCI-EORTC Data

Additional BAY 43-9006 data being presented at this year's AACR-NCI-EORTC
meeting include:

  -- Phase I study of BAY 43-9006, a novel RAF kinase and VEGRF inhibitor,
     in combination with taxotere in patients with advanced, solid tumors.
     A. Awada, MD. (Poster #381)
  -- Phase II antitumor activity of BAY 43-9006, a novel RAF kinase and
     VEGRF inhibitor, in patients with sarcoma enrolled in a randomized
     discontinuation study. I. Judson, MD.  (Poster #382)


  About Onyx Pharmaceuticals, Inc.


Onyx Pharmaceuticals, Inc. is engaged in the development of novel cancer
therapies that target the molecular basis of cancer.  With its collaborators,
the company is developing small molecule drugs, including BAY 43-9006 with
Bayer Pharmaceuticals Corporation.  For more information about Onyx's pipeline
and activities, visit the company's web site at: http://www.onyx-pharm.com/ .

About Bayer Pharmaceuticals Corporation

Bayer Pharmaceuticals Corporation ( http://www.bayerpharma.com/ ) is part of
the worldwide operations of Bayer HealthCare AG, a subgroup of Bayer AG.

Bayer HealthCare, with sales of approximately 8.9 billion Euro in 2003, is one
of the world's leading, innovative companies in the health care and medical
products industry.

The company combines the global activities of the divisions Animal Health,
Biological Products, Consumer Care, Diagnostics and Pharmaceuticals.  About
34,600 people are employed by Bayer HealthCare worldwide.

Our aim is to discover and manufacture innovative products that will improve
human and animal health worldwide. Our products enhance well being and quality
of life by diagnosing, preventing and treating disease.

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 Bayer's public reports filed with the Frankfurt
Stock Exchange and with the U.S. Securities and Exchange Commission (including
its Form 20-F).  Bayer 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, regulatory processes and commercialization
efforts of BAY 43-9006. 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 Onyx's Annual Report on Form 10-K filed
with the Securities and Exchange Commission on March 15, 2004 under the heading
"Additional Business Risks" 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, events or
circumstances after the date of this release except as required by law. 

DATASOURCE: Onyx Pharmaceuticals, Inc.; Bayer Pharmaceuticals Corporation



CONTACT:  Mark Bennett of Bayer Pharmaceuticals Corporation,

[phone], onsite, or Helmut Schaefers of Bayer HealthCare

Communications, [phone]; Julie Wood of Onyx Pharmaceuticals, Inc.,

[phone]; Geoff Curtis of GCI Group, [phone]



Web Site:  http://www.onyx-pharm.com/

http://www.bayerpharma.com/

http://www.clinicaltrials.gov/ 

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