( BW)(AMGEN-INC)(AMGN) Romiplostim Data Show Potential Long-Term
Efficacy and Safety in Adults with Chronic ITP

    Business Editors/Health/Medical Writers

    COPENHAGEN, Denmark--(BUSINESS WIRE)--June 15, 2008--

    Results Show Romiplostim Increased and Sustained Platelet Counts
with Extended Treatment

    Amgen Inc. (NASDAQ: AMGN) today announced updated results from the
ongoing, open-label extension study on the long-term safety and
efficacy of romiplostim in adult patients with chronic immune
thrombocytopenic purpura (ITP), a chronic and serious autoimmune
disorder characterized by low platelet counts in the blood. The
updated results continue to show that romiplostim increased and
sustained platelet counts with extended treatment, and reduced the
need for concurrent and rescue ITP medications.

    The updated results from the long-term study show that overall 87
percent of patients achieved a platelet response defined as a platelet
count of 50,000 platelets per microliter or doubling of the baseline
platelet count (124/142). The overall median baseline platelet count
was 17,000 platelets per microliter. The average treatment period was
65 weeks, and the longest duration of treatment was 156 weeks. The
results were presented today as an oral presentation at the 13th
Congress of the European Hematology Association (Abstract # 1421).

    "Currently, romiplostim is the only thrombopoietic treatment for
adult chronic ITP for which there is three years of follow-up data,"
said Professor Adrian Newland, Department of Haematology, The Royal
London Hospital, Whitechapel, London, UK. "This is the longest ITP
study and the findings demonstrate the potential of romiplostim as a
long-term treatment option for a patient population with limited
treatment options."

    Additional data presented include:

    --  Platelet response achieved: Overall, 87 percent (124/142) of
        patients achieved a platelet response. A platelet response was
        achieved by 30 percent (42/138) of patients after the first
        dose and by 51 percent (71/138) of patients after the third
        dose.

    --  Platelet counts increased: Platelet counts of
        romiplostim-treated patients were increased from baseline by
        20,000 platelets per microliter more than half of the time in
        86 percent of patients and more than four-fifths of the time
        in 57 percent of patients.

    --  Platelet counts maintained: Ad hoc analysis showed response
        durability, defined as platelet counts greater than 50,000
        platelets per microliter, was maintained for greater than or
        equal to 10 consecutive weeks in 78 percent of patients
        (102/131), greater than or equal to 25 weeks in 54 percent of
        patients (66/122), and greater than or equal to 52 consecutive
        weeks in 35 percent of patients (29/84).

    --  Discontinuation or reduction of concurrent ITP medications: Of
        patients receiving concurrent ITP medications (such as
        corticosteroids) at baseline, 84 percent of patients (27/32)
        discontinued or reduced their dose by greater than 25 percent.

    --  Decreased use of rescue medications: Patients using rescue
        medications (defined as any additional ITP medicines needed to
        increase platelet counts) decreased from 23 percent (33/142)
        during weeks 1-12 to 15 percent during weeks 24-36, and
        remaining between 12-18 percent during weeks 130-132.

    In this study, adverse events (AEs) did not increase in frequency
during the course of the trial. AEs were reported in 95 percent of
patients, with most mild to moderate in severity and transient in
duration. The most common were headache (37 percent), nasopharyngitis
(32 percent), contusion, fatigue and epistaxis (each 30 percent).

    Treatment-related and serious AEs were reported in 36 percent and
31 percent of patients, respectively. Nine percent of serious AEs were
considered treatment-related. Of the patients who discontinued
treatment, seven percent (10/142) stopped due to AEs.

    Bone marrow reticulin was reported in samples from eight patients
with no evidence of collagen fibrosis or chronic idiopathic
myelofibrosis. Thrombotic/thromboembolic events were reported in seven
patients, of which six had pre-existing risk factors. To date, one
patient developed a neutralizing antibody to romiplostim; however, it
did not cross react with thrombopoietin and it was absent upon
re-testing four months after romiplostim treatment was stopped.

    About the Study

    This ongoing, open-label study is assessing the safety and
efficacy of long-term administration of romiplostim in both
splenectomized and non-splenectomized adult chronic ITP patients. As
of July 13, 2007, 143 patients had enrolled and 142 were treated with
romiplostim. Sixty-seven percent of patients were female, and of the
enrolled patients, 60 percent had undergone a splenectomy (removal of
the spleen).

    Eligible patients had completed a previous ITP romiplostim study,
and had a baseline platelet count of less than 50,000 platelets per
microliter, with no significant change in medical history. The
romiplostim starting dose was 1 ug/kg by subcutaneous injection and
was adjusted to maintain a platelet count between 50,000 and 250,000
platelets per microliter.

    About Adult ITP

    Platelets are blood cells needed to prevent bleeding. Low platelet
counts leave adult ITP patients open to sudden serious bleeding
events, making it impossible to arrest blood flow. The risk for
serious bleeding events increases when platelet counts drop to less
than 30,000 platelets per microliter.

    There are limited approved treatments (i.e., corticosteroids,
immunglobulins) or surgical therapy (removal of the spleen) available
to adult patients with chronic ITP. Currently, there are 140,000
treated chronic ITP patients in the U.S. and Europe. ITP affects about
twice as many adult women as men.

    With ITP, platelets are destroyed by the patient's own immune
system. ITP has historically been considered a disease of platelet
destruction. However, recent data also suggest that the body's natural
platelet production processes are unable to compensate for low levels
of platelets in the blood. Increasing the rate of platelet production
may address low platelet levels associated with ITP.

    About Romiplostim

    Romiplostim, Amgen's first peptibody, is a novel engineered
therapeutic fusion protein with attributes of both peptides and
antibodies, but is distinct from each. Romiplostim works similarly to
thrombopoietin (TPO), a natural protein in the body. Romiplostim
stimulates the TPO receptor, which is necessary for growth and
maturation of bone marrow cells that produce platelets.

    Amgen has filed for regulatory approval of romiplostim for use in
the treatment of thrombocytopenia in adults with chronic ITP in the
United States (U.S.), European Union, Australia and Canada. Regulatory
authorities in the U.S., Australia and Canada have granted priority
review of Amgen's application.

    About Amgen

    Amgen discovers, develops, manufactures and delivers innovative
human therapeutics. A biotechnology pioneer since 1980, Amgen was one
of the first companies to realize the new science's promise by
bringing safe and effective medicines from lab, to manufacturing
plant, to patient. Amgen therapeutics have changed the practice of
medicine, helping millions of people around the world in the fight
against cancer, kidney disorder, rheumatoid arthritis, and other
serious illnesses. With a deep and broad pipeline of potential new
medicines, Amgen remains committed to advancing science to
dramatically improve people's lives. To learn more about our
pioneering science and our vital medicines, visit www.amgen.com.

    Forward-Looking Statement

    This news release contains forward-looking statements that are
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    --30--MTB/la*

    CONTACT: Amgen, Thousand Oaks
             Sabeena Ahmad, +41 41 3692 530 (EU media, oncology)
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