Early Data Presented from Investigational Molecules that Target
Apoptosis and Growth Regulation Pathways

Abstract Numbers: 3162, 1326, 3999, 2804, 4001, 3994

SAN DIEGO–(BUSINESS WIRE)–April 15, 2008–Amgen (NASDAQ:AMGN)
today announced data generated by the company's robust oncology
research and development programs in the areas of apoptosis
(programmed cell death) and cell growth regulation. The data,
presented at the American Association for Cancer Research (AACR)
Annual Meeting in San Diego were from five preclinical studies
evaluating anti-tumor activity, pharmacodynamics, and potential
pre-clinical and clinical biomarkers for investigational molecules AMG
655, AMG 479 and AMG 102.

“We are excited to be pushing the boundaries of knowledge around
known oncology pathways such as apoptosis and growth regulation by
exploring new and innovative approaches to attack tumor cells,” said
David Chang, M.D., vice president, Global Oncology Development at
Amgen. “While still early, we are pleased to be presenting a broad
spectrum of data at this meeting reinforcing the biologic plausibility
of targeting newly-discovered approaches to attack cancer via these
pathways.”

Targeting Apoptosis via Death Receptors

AMG 655 is an investigational fully human monoclonal antibody
(mAb) agonist directed against death receptor 5 (DR5). AMG 655 is
designed to activate caspases and induce apoptosis in sensitive tumor
cells.

Apoptosis is a form of cell suicide in which a controlled sequence
of biochemical events leads to cell death. In cancer, the
dysregulation of apoptosis is critical in the development and survival
of tumors. Apoptosis can be triggered by cell stress and DNA damage,
but it also occurs normally during development of the body.

Data presented at AACR showed that, when combined with the
chemotherapeutic agent gemcitabine, AMG 655 enhanced apoptosis in both
in vitro, and in vivo, pancreatic cancer models. The combination of
AMG 655 and gemcitabine was more effective in these models than either
agent alone.

In another study, AMG 655 was combined with a chemotherapeutic
agent (irinotecan or 5-fluorouracil (5-FU)) enhanced apoptosis
relative to either agent alone in both in vitro and in vivo colon
cancer cell models. AMG 655 is currently being tested against
colorectal cancer in a Phase 1b/2 clinical trial.

In a third study, positron emission tomography (PET) was evaluated
for its potential as a non-invasive method to measure receptor
occupancy of DR5, the target of AMG 655. The preclinical results
support the potential of using PET for imaging DR5 positive tumors and
measuring receptor occupancy in patients. This imaging technology also
is being applied to the study of other antibodies in the Amgen
pipeline.

Targeting Growth Regulation in Cancer

AMG 479 is an investigational fully human monoclonal antibody that
binds to insulin-like growth factor-1 receptor (IGF-1R) without
cross-reacting with the closely related insulin receptor.

IGF-1 and IGF-2 activate the IGF-1R receptor, which is expressed
in many human cancers. The expression of IGF-1 mediates tumor
proliferation and reduces apoptosis and is associated with higher
incidences and more aggressive progression of many common cancers.

Activation of these growth and survival pathways may allow tumor
cells to resist the apoptosis-inducing activity of chemotherapy,
radiation, and hormonal therapy and can increase cellular
proliferation.

The preclinical data presented showed that AMG 479 inhibited more
than 80 percent of IGF-1 induced growth activation in certain sarcoma
cell line. Treatment of these cell lines with a combination of AMG 479
and cyclophosphamide resulted in significant (p=0.0020 vs. AMG 479,
p=0.0002 vs. cyclophosphamide) tumor growth inhibition compared to
either treatment alone. AMG 479 is currently in phase 2 Ewing's
sarcoma trial.

AMG 102

AMG 102 is an investigational fully human monoclonal antibody that
targets the action of anti-hepatocyte growth factor (HGF)/scatter
factor (SF). HGF signaling through its receptor c-Met appears to play
an important role in many types of human cancers.

The HGF/SF:c-Met pathway mediates a large number of normal
activities in cells of epithelial origin – including proliferation,
survival, migration, and invasion. The dysregulation of the
HGF/SF:c-Met pathway appears to play an important role in many types
of cancers, often leading to tumorigenesis and metastasis.

The data presented at AACR examined exploratory biomarkers that
might be useful pharmacodynamic or patient enrichment markers for
HGF/SF:c-Met therapies like AMG 102. Preclinical glioblastoma tumor
xenograft models were treated with a single dose of AMG 102 ranging
from 3- 300 ug IP. On days 3 and 7 after treatment initiation, plasma
was harvested and levels of tumor-derived total human HGF, soluble
human c-Met and CD44v6 (a c-Met associated protein) were quantified.
Plasma samples from patients enrolled in the AMG 102 first-in-human
trial were also examined. Total HGF and soluble c-Met levels were
determined in plasma from patients in sequential dose cohorts (4-6
pts/cohort) that had been treated with AMG 102 at 0.5, 1, 3, 5, 10, or
20 mg/kg.

The study found that the treatment of tumor bearing preclinical
models or cancer patients with AMG 102 gave rise to a dose-dependent
increase in circulating HGF levels which suggests that monitoring HGF
levels during treatment may serve as a biomarker for inhibition of the
HGF/SF:c-Met pathway

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About Amgen

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SOURCE: Amgen