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UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Commission file number 000-12477

(805) 447-1000

Securities registered pursuant to Section 12(g) of the Act:

Common stock, $0.0001 par value; preferred share purchase rights;

     Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     Yes þ          No o

      Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.     þ

      Indicate by check mark whether the registrant is an accelerated filer.     þ

      The approximate aggregate market value of voting and non-voting stock held by non-affiliates of the registrant was $82,599,577,717 as of February 13, 2004^A

1,280,068,013

     ^A Excludes 2,820,793 shares of common stock held by directors and officers, and any stockholders whose ownership exceeds five percent of the shares outstanding, at February 13, 2004. Exclusion of shares held by any person should not be construed to indicate that such person possesses the power, directly or indirectly, to direct or cause the direction of the management or policies of the registrant, or that such person is controlled by or under common control with the registrant.

INDEX

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PART I

Item 1.     BUSINESS

Overview

      Amgen Inc. (including its subsidiaries, “Amgen” or the “Company”) is a global biotechnology company that discovers, develops, manufactures, and markets human therapeutics based on advances in cellular and molecular biology. On July 15, 2002, Amgen acquired all of the outstanding common stock of Immunex Corporation (“Immunex”) for stock and cash valued at $17.8 billion in a transaction accounted for as a business combination (see Note 3, “Immunex acquisition” to the Consolidated Financial Statements). Immunex was a leading biotechnology company dedicated to developing immune system science to protect human health. The acquisition has enhanced Amgen’s strategic position within the biotechnology industry by strengthening and diversifying its (1) product base and product pipeline in key therapeutic areas, and (2) discovery research capabilities in proteins and antibodies.

      The Company markets human therapeutic products in the areas of hematology, oncology, and inflammation. The Company’s key products include EPOGEN® (Epoetin alfa), Aranesp® (darbepoetin alfa), Neulasta® (pegfilgrastim), NEUPOGEN® (Filgrastim), and ENBREL® (etanercept), which is marketed under a co-promotion agreement with Wyeth. The Company’s other products include Kineret® (anakinra) and Stemgen® (Ancestim).

      EPOGEN® and Aranesp® stimulate the production of red blood cells. EPOGEN® is marketed in the United States for the treatment of anemia associated with chronic renal failure in patients on dialysis. Aranesp® is marketed in the United States, most countries in Europe, Australia, and New Zealand for the treatment of anemia associated with chronic renal failure, including patients on dialysis and patients not on dialysis. Aranesp® is also marketed in the United States for the treatment of chemotherapy-induced anemia in patients with non-myeloid malignancies. Aranesp® is marketed in Europe for the treatment of anemia in adult cancer patients with solid tumors receiving chemotherapy and for the treatment of chemotherapy-induced anemia in adult patients with non-myeloid malignancies.

      Neulasta® and NEUPOGEN® selectively stimulate the production of neutrophils, one type of white blood cell. Neulasta® is marketed in the United States to decrease the incidence of infection, as manifested by febrile neutropenia in patients with non-myeloid malignancies receiving myelosuppressive anti-cancer drugs associated with a clinically significant incidence of febrile neutropenia. Neulasta® is marketed in most countries in Europe for the reduction in the duration of neutropenia and the incidence of febrile neutropenia in patients with cytotoxic chemotherapy for malignancy. NEUPOGEN® is marketed in the United States, certain countries in Europe, Canada, and Australia for use in decreasing the incidence of infection in patients undergoing myelosuppressive chemotherapy. In addition, NEUPOGEN® is marketed in most of these countries for use in increasing neutrophil counts in various other treatment modalities.

      ENBREL® blocks the biologic activity of tumor necrosis factor (“TNF”) by competitively inhibiting TNF, a substance induced in response to inflammatory and immunological responses. ENBREL® is marketed in the United States for reducing the signs and symptoms, improving physical function, and inhibiting the progression of structural damage in patients with moderately to severely active rheumatoid arthritis; and for reducing the signs and symptoms and inhibiting the progression of structural damage in patients with psoriatic arthritis. In addition, ENBREL is approved for reducing the signs and symptoms of moderately to severely active polyarticular-course juvenile rheumatoid arthritis in patients who have had an inadequate response to one or more disease-modifying medicines; and to treat the signs and symptoms in patients with active ankylosing spondylitis.

      The Company maintains a sales and marketing force in the United States, Europe, Canada, Australia, and New Zealand. In addition, Amgen has entered into licensing and/or co-promotion agreements to market certain of its products including Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL® in certain geographic areas outside of the United States.

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      The Company focuses its research and development (“R&D”) efforts on human therapeutics delivered in the form of proteins, monoclonal antibodies, and small molecules in the areas of hematology, oncology, inflammation, metabolic and bone disorders, and neuroscience. The Company has research facilities in the United States, and has clinical development staff in the United States, Europe, Canada, Australia, and Japan. In addition to internal R&D efforts, the Company has acquired certain product and technology rights and has established R&D collaborations.

      The Company manufactures EPOGEN®, Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL®. Amgen operates commercial manufacturing facilities located in the United States, Puerto Rico, and a packaging and distribution center in the Netherlands. Additional supply of ENBREL® is produced by our contract manufacturer, Boehringer Ingelheim Pharma KG (“BI Pharma”).

      The Company was incorporated in California in 1980 and was merged into a Delaware corporation in 1987. Amgen’s principal executive offices are located at One Amgen Center Drive, Thousand Oaks, California 91320-1799.

Products

      EPOGEN® (Epoetin alfa) is Amgen’s registered trademark for its recombinant human erythropoietin product, a protein that stimulates red blood cell production. Red blood cells transport oxygen to all cells of the body. Without adequate amounts of erythropoietin, the red blood cell count is reduced, thereby diminishing the ability of the blood to deliver sufficient amounts of oxygen to the body, resulting in anemia. People with chronic renal failure suffer from anemia because they do not produce sufficient amounts of erythropoietin, which is normally produced in healthy kidneys. Amgen markets EPOGEN® for the treatment of anemia associated with chronic renal failure for patients who are on dialysis. EPOGEN® is indicated to elevate or maintain the red blood cell level (as determined by hematocrit or hemoglobin measurements) and to decrease the need for blood transfusions in these patients.

      In the United States, Amgen was granted rights to manufacture and market recombinant human erythropoietin under a licensing agreement with Kirin-Amgen, Inc. (“KA”), a joint venture between Kirin Brewery Company, Limited (“Kirin”) and Amgen (see “Joint Ventures and Business Relationships — Kirin Brewery Company, Limited”). EPOGEN® is approved for the treatment of anemia associated with chronic renal failure and for the treatment of anemia in children with chronic renal failure who are on dialysis.

      The Company has retained exclusive rights to market EPOGEN® in the United States for dialysis patients. Amgen granted Ortho Pharmaceutical Corporation (which has assigned its rights under the Product License Agreement to Ortho Biotech Products, L.P., a subsidiary of Johnson & Johnson, hereafter referred to as “Johnson & Johnson”) a license to commercialize recombinant human erythropoietin as a human therapeutic in the United States in all markets other than dialysis (see “Joint Ventures and Business Relationships — Johnson & Johnson”). Johnson & Johnson markets recombinant human erythropoietin under the trademark PROCRIT® in the United States (see Note 1, “Summary of significant accounting policies — Product sales” to the Consolidated Financial Statements).

      EPOGEN® sales for the years ended December 31, 2003, 2002, and 2001 were $2,434.7 million, $2,260.6 million, and $2,108.5 million, respectively.

      Aranesp® (darbepoetin alfa) is Amgen’s registered trademark for its erythropoiesis stimulating protein, a protein that stimulates red blood cell production. A reduced red blood cell count can result in anemia (see “— EPOGEN® (Epoetin alfa)”). Since this protein leaves the body more slowly, Aranesp® should be administered less frequently than Epoetin alfa, thus simplifying anemia management for patients and health care providers.

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      The Company has an agreement with Kirin to jointly develop darbepoetin alfa through its joint venture, KA. Amgen was granted an exclusive license by KA to manufacture and market darbepoetin alfa in the United States, all European countries, Canada, Australia, New Zealand, Mexico, and all Central and South American countries. In 2001, the Company received approval to market Aranesp® in the United States, most countries in Europe, Australia, and New Zealand for the treatment of anemia associated with chronic renal failure, including patients on dialysis and patients not on dialysis. In July 2002, the Company received approval to market and launched Aranesp® in the United States for the treatment of chemotherapy-induced anemia in patients with non-myeloid malignancies. In August 2002, Aranesp® was approved in Canada for the treatment of anemia associated with chronic renal failure, including patients on dialysis and patients not on dialysis. In August 2002 and June 2003, respectively, the European Commission approved Aranesp® for the treatment of anemia in adult cancer patients with solid tumors receiving chemotherapy and for the treatment of chemotherapy-induced anemia in adult patients with non-myeloid malignancies. The Company commenced launching Aranesp® in Europe on a country-by-country basis as reimbursement has been established. Amgen markets darbepoetin alfa under the brand name Nespo® in Italy.

      Worldwide Aranesp® sales for the years ended December 31, 2003, 2002 and 2001 were $1,543.8 million, $415.6 million and $41.5 million, respectively.

      Neulasta® (pegfilgrastim) is Amgen’s registered trademark for a protein that selectively stimulates production of certain white blood cells known as neutrophils and is based on the Filgrastim molecule. A polyethylene glycol molecule or “PEG” is added to enlarge the Filgrastim molecule, thereby extending its half-life and causing it to be removed more slowly from the body. This allows for administration as a single dose per chemotherapy cycle compared with NEUPOGEN® which requires more frequent dosing.

      Amgen was granted rights to manufacture and market pegfilgrastim under a licensing agreement with KA in the United States, Europe, Canada, Australia, and New Zealand. In January 2002, the U.S. Food and Drug Administration (“FDA”) approved Neulasta® for decreasing the incidence of infection, as manifested by febrile neutropenia, in patients with non-myeloid malignancies receiving myelosuppressive anti-cancer drugs associated with a clinically significant incidence of febrile neutropenia. The Company launched Neulasta® in the United States in April 2002 for this indication. In August 2002, the European Commission approved Neulasta® for the reduction in the duration of neutropenia and the incidence of febrile neutropenia in patients with cytotoxic chemotherapy for malignancy. In January 2003, the Company commenced launching Neulasta® in Europe on a country-by-country basis as reimbursement has been established. Amgen markets pegfilgrastim under the brand name Neupopeg^TM in Italy.

      Neulasta® sales for the year ended December 31, 2003 and 2002 were $1,255.0 million and $463.5 million, respectively.

      NEUPOGEN® (Filgrastim) is Amgen’s registered trademark for its recombinant-methionyl human granulocyte colony-stimulating factor (“G-CSF”), a protein that selectively stimulates production of certain white blood cells known as neutrophils. Neutrophils defend against infection. Treatments for various diseases and diseases themselves can result in extremely low numbers of neutrophils, a condition called neutropenia. Myelosuppressive chemotherapy, one treatment option for individuals with certain types of cancers, targets cell types which grow rapidly, such as tumor cells, neutrophils, and other types of blood cells. Myelosuppressive chemotherapy can be administered with the intent to cure cancer (curative setting) or treat other complications of cancer by managing tumor growth (palliative setting). NEUPOGEN® is prescribed more frequently in the curative setting. Providing NEUPOGEN® as an adjunct to myelosuppressive chemotherapy can reduce the duration of neutropenia and thereby reduce the potential for infection.

      Severe chronic neutropenia is an example of disease-related neutropenia. In severe chronic neutropenia, the body fails to manufacture sufficient neutrophils. Daily administration of NEUPOGEN® has been shown

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      Patients undergoing bone marrow transplantation may be treated with NEUPOGEN® to accelerate recovery of neutrophils following chemotherapy and bone marrow infusion. NEUPOGEN® also has been shown to induce immature blood cells (progenitor cells, sometimes referred to as stem cells) to migrate (mobilize) from the bone marrow into the blood circulatory system. When these peripheral blood progenitor cells (“PBPC”) are collected from the blood, stored, and re-infused (transplanted) after high dose chemotherapy, recovery of platelets, red blood cells, and neutrophils is accelerated. PBPC transplantation may be an alternative to autologous bone marrow transplantation for some cancer patients.

      Amgen was granted rights to manufacture and market G-CSF under a licensing agreement with KA in the United States, Europe, Canada, Australia, and New Zealand. In May 2002, the Company acquired certain rights related to the commercialization of NEUPOGEN® and GRANULOKINE® (Filgrastim) and pegfilgrastim in the European Union (“EU”) from F. Hoffmann-La Roche Ltd (“Roche”). Prior to this acquisition, NEUPOGEN® and GRANULOKINE® were commercialized in the EU under a co-promotion agreement between Amgen and Roche. Roche will continue as the licensee for Filgrastim and pegfilgrastim in certain countries outside the United States and the EU. Amgen markets Filgrastim under the brand name GRANULOKINE® in Italy.

      In the United States, NEUPOGEN® was initially indicated to decrease the incidence of infection as manifested by febrile neutropenia for patients with non-myeloid malignancies undergoing myelosuppressive chemotherapy. Subsequently, the FDA approved NEUPOGEN® for additional indications: to reduce the duration of neutropenia and neutropenia-related consequences for patients with non-myeloid malignancies undergoing myeloablative chemotherapy followed by bone marrow transplantation; to reduce the incidence and duration of neutropenia-related consequences in symptomatic patients with congenital neutropenia, cyclic neutropenia, or idiopathic neutropenia (collectively, severe chronic neutropenia); for use in mobilization of PBPC for stem cell transplantation; and to reduce the recovery time of neutrophils and the duration of fever following induction or consolidation chemotherapy treatment in adult patients with acute myelogenous leukemia (“AML”). In Europe, Canada, and Australia, NEUPOGEN® is marketed for these same indications.

      Worldwide NEUPOGEN® sales for the years ended December 31, 2003, 2002, and 2001 were $1,266.7 million, $1,379.6 million, and $1,346.4 million, respectively.

      ENBREL® (etanercept) is Amgen’s registered trademark for its TNF receptor fusion protein that inhibits the binding of TNF to TNF receptors, that can result in a significant reduction in inflammatory activity. ENBREL® was launched in November 1998 by Immunex. Amgen acquired the rights to ENBREL® in July 2002 as part of its acquisition of Immunex. In addition, the Company has a co-promotion agreement and a global supply agreement with Wyeth (see “Joint Ventures and Business Relationships — Wyeth”).

      In the United States, ENBREL® is approved for reducing the signs and symptoms, improving physical function, and inhibiting the progression of structural damage in patients with moderately to severely active rheumatoid arthritis; for reducing the signs and symptoms of moderately to severely active polyarticular-course juvenile rheumatoid arthritis in patients who have had an inadequate response to one or more disease-modifying medicines; for reducing the signs and symptoms of active arthritis and inhibiting structural damage in patients with psoriatic arthritis; and to treat the signs and symptoms in patients with active ankylosing spondylitis.

      ENBREL® sales for the year ended December 31, 2003 and the period from July 16, 2002 through December 31, 2002 were $1,300.0 million and $362.1 million, respectively.

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Selected Product Candidates

      The Company focuses its R&D efforts on human therapeutics delivered in the form of proteins, monoclonal antibodies, and small molecules in the areas of hematology, oncology, inflammation, metabolic and bone disorders, and neuroscience. (see “Management’s Discussion and Analysis of Financial Condition and Results of Operations (“MD&A”) — Financial Outlook — Forward looking statements and factors that may affect Amgen — Our product development efforts may not result in commercial products”). The following is a selection of some of the Company’s product candidates in various therapeutic areas.

      Certain tissue growth factors are believed to play a role in tissue protection, regeneration, and/or repair processes. Mucositis is a side effect often experienced by patients undergoing radiation therapy and chemotherapy and is characterized as the irritation or ulceration of the lining of the gastrointestinal tract. Amgen currently is conducting research with palifermin to treat oral mucositis. A phase 3 clinical trial evaluating the effects of palifermin in decreasing the incidence and duration of oral mucositis in patients with hematologic malignancies undergoing chemotherapy and radiation therapy with autologous PBPC transplantation was completed in the latter part of 2002. In 2003, the Company announced that analysis of the data suggested that palifermin reduced the duration and incidence of severe oral mucositis in those who received it, as compared to placebo.

      Amgen and Abgenix Inc. (“Abgenix”) have an agreement providing for the development and commercialization of panitumumab (ABX-EGF), a fully human monoclonal antibody created by Abgenix (see “Joint Ventures and Business Relationships — Abgenix Inc.). Panitumumab targets the receptor pathway for human epidermal growth factor, or EGFr, which is expressed on some of the most prevalent human solid tumor types, including lung, colorectal, pancreatic, renal cell, prostate, and esophageal cancers. Amgen and Abgenix have pursued a series of phase 2 clinical trials to evaluate panitumumab for the treatment of several types of cancer. In January 2004, Amgen initiated two pivotal studies to evaluate panitumumab as a third-line therapy in colorectal cancer patients.

      In December 2000, the Company acquired the rights from Immunomedics, Inc. (“Immunomedics”) to develop and commercialize epratuzumab, a potential treatment for non-Hodgkin’s lymphoma (“NHL”). In November 2003, the Company announced its decision not to commence a registration study in NHL and plans to seek another party for the development and commercialization of its rights to epratuzumab.

      The inflammatory response is essential for defense against harmful microorganisms and for the repair of damaged tissues. The failure of the body’s control mechanisms for the inflammatory response can result in conditions such as rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. In January 2003, the Company announced positive results of a phase 3 clinical study assessing the efficacy and tolerability of ENBREL® in the treatment of moderate to severe plaque psoriasis. Psoriasis is an inflammatory disease which is characterized by chronic inflammation of the skin that drives the formation of skin plaques. In July 2003, the Company submitted a supplemental Biologics License Application (sBLA) with the FDA for the use of ENBREL® to treat moderate to severe plaque psoriasis.

      In 2001, the Company initiated a phase 2 clinical trial of a second generation inhibitor of tumor necrosis factor, pegylated soluble tumor necrosis factor-receptor type 1 (“PEG-sTNF-R1”) in combination with Kineret®, the Company’s interleukin-1 blocker, in patients with rheumatoid arthritis. This phase 2 clinical trial was stopped in February 2003 as the combination resulted in increased safety concerns with no increased efficacy. The Company completed a phase 2 clinical trial of PEG-sTNF-R1 for patients with rheumatoid arthritis and is currently evaluating the data. The Company is also evaluating PEG-sTNF-R1 in other indications.

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      A focus of the Company’s R&D effort is in the area of hyperparathyroidism (“HPT”). HPT is a disorder that results from excessive secretion of parathyroid hormone (“PTH”) from the parathyroid gland. Symptoms of HPT include bone loss, muscle weakness, depression, and forgetfulness. Secondary HPT is commonly seen as a result of kidney failure, affecting a majority of dialysis patients. Primary HPT principally afflicts post-menopausal women. The Company has a license agreement with NPS Pharmaceuticals, Inc. (“NPS”) for Amgen to develop and commercialize calcimimetic small molecules based on NPS’s proprietary calcium receptor technology for the treatment of HPT. The Company has conducted separate phase 2 clinical trials for primary and secondary HPT with a second-generation calcimimetic compound, Sensipar^TM (cinacalcet HCl) (“Sensipar^TM”). In July 2003, the Company announced the successful completion of three phase 3 studies supporting the use of Sensipar^TM in secondary HPT. In March 2004, the FDA approved Sensipar^TM for the treatment of secondary HPT in chronic kidney disease patients on dialysis and for the treatment of hypercalcemia in patients with parathyroid carcinoma.

      Bone health is maintained through regulation of the competing activities of bone forming cells (osteoblasts) and bone resorbing cells (osteoclasts). Bone loss is the result of an imbalance between bone formation and resorption (bone remodeling), where the amount of bone resorbed exceeds the amount of bone formed. Receptor Activator of Nuclear Factor kappa B Ligand (RANKL) is a key-mediator of the resorptive phase of the bone remodeling process. AMG 162 is a fully human monoclonal antibody that specifically and with high affinity binds and neutralizes RANKL. In preclinical studies, AMG 162 has been shown to inhibit the osteoclast mediated bone destruction characteristic of postmenopausal osteoporosis. In addition, AMG 162 has been shown to reduce bone resorption associated with bone metastases of cancer. Cancer can metastasize to bone leading to bone destruction, fractures, and bone pain. The Company completed phase 1 studies with AMG 162 in osteoporosis and cancer. Data from these studies validated the importance of this pathway in the pathology of bone disorders. The Company is currently conducting further studies with AMG 162 in osteoporosis and cancer.

      In September 2003, the Company announced an agreement with Biovitrum AB under which the Company received exclusive rights to develop and commercialize Biovitrum’s small molecule 11ßHSD1 enzyme inhibitors for the treatment of metabolic diseases and certain other medical disorders. The most advanced compound included in the agreement is BVT.3498, for type 2 diabetes.

      The Company has discovery programs in the neurosciences. Neurotrophic factors are proteins which play a role in nerve cell protection and regeneration and which may therefore be useful in treating a variety of neurological disorders, including neurodegenerative diseases of the central and peripheral nervous systems, and also nerve injury or trauma. In 1999, the Company discontinued development of glial cell line derived neurotrophic factor (“GDNF”) after a phase 1/2 trial of GDNF in Parkinson’s disease failed to demonstrate a statistically significant benefit. However, based on favorable phase 1 clinical data from investigator-sponsored research, the Company is currently in phase 2 clinical studies of GDNF using a different treatment protocol for possible use in the treatment of Parkinson’s disease.

Joint Ventures and Business Relationships

      The Company generally discovers, develops, manufactures, and markets its products. From time to time, the Company may enter into joint ventures and other business relationships to provide additional development, manufacturing, and marketing capabilities. In addition to internal R&D efforts, the Company has acquired certain product and technology rights and has established R&D collaborations to enhance the Company’s internally developed product pipeline.

      The Company formed KA, a 50-50 joint venture with Kirin in 1984. KA develops and commercializes certain of the Company’s and Kirin’s technologies which have been transferred to this joint venture. KA has

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      KA has also given exclusive licenses to Kirin to manufacture and market: 1) recombinant human erythropoietin in Japan, 2) darbepoetin alfa in Japan, the People’s Republic of China, Taiwan, Korea, and certain other countries in Southeast Asia, and 3) G-CSF and pegfilgrastim in Japan, Taiwan and Korea. Kirin markets recombinant human erythropoietin and G-CSF in the People’s Republic of China under a separate agreement. Kirin markets its recombinant human erythropoietin product in Japan under the trademark ESPO®. Kirin markets its G-CSF product in its respective territories under the trademark GRAN®. KA has licensed to Johnson & Johnson rights to recombinant human erythropoietin in certain geographic areas of the world (see “— Johnson & Johnson”). Under its agreement with KA, Johnson & Johnson pays a royalty to KA based on sales.

      In connection with its various license agreements with KA, the Company pays KA royalties based on product sales and also receives payment for conducting certain R&D activities on behalf of KA (See Note 2, “Related party transactions” to the Consolidated Financial Statements).

      Amgen granted Johnson & Johnson a license to commercialize recombinant human erythropoietin as a human therapeutic in the United States in all markets other than dialysis. In the United States, all recombinant human erythropoietin sold by Johnson & Johnson is manufactured by Amgen and sold by Johnson & Johnson under the trademark PROCRIT® (Epoetin alfa). PROCRIT® brand Epoetin alfa is identical to EPOGEN® brand Epoetin alfa, which is manufactured by Amgen and sold by Amgen in the United States dialysis market. Pursuant to the license agreement with Johnson & Johnson, the Company earns a 10% royalty on sales of PROCRIT® by Johnson & Johnson in the United States.

      Outside the United States, with the exception of the People’s Republic of China and Japan, Johnson & Johnson was granted rights to manufacture and commercialize recombinant human erythropoietin as a human therapeutic for all uses under a licensing agreement with KA. With respect to its sales outside of the United States, Johnson & Johnson manufactures and commercializes its own brand of Epoetin alfa which is then sold throughout the world by Johnson & Johnson under various trademarks such as EPREX® and ERYPO®. The Company is not involved in the manufacture of Epoetin alfa sold by Johnson & Johnson outside of the United States.

      Amgen and Wyeth market and sell ENBREL® in the United States and Canada for all approved indications other than oncology. The rights to promote ENBREL® in the United States and Canada for oncology indications are reserved to Amgen. The rights to market ENBREL® outside of the United States and Canada are reserved to Wyeth. Under a co-promotion agreement, a management committee comprised of equal representation from Wyeth and Amgen is responsible for overseeing the marketing and sales of ENBREL® including: strategic planning, the approval of an annual marketing plan, product pricing, and the establishment of a brand team. The brand team, with equal representation from each party, prepares and implements the annual marketing plan, which includes a minimum level of financial and sales personnel commitment from each party, and is responsible for all sales activities. Further, pursuant to the co-promotion agreement, Wyeth and Amgen each pay a defined percentage of all selling and marketing expenses approved by the management committee. In addition, Amgen pays Wyeth a percentage of the annual gross profits of ENBREL®, which reflect the sharing of manufacturing costs, in the United States and Canada attributable to all indications for ENBREL®, other than oncology indications, on a scale that increases as gross profits

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      The Company also has a global supply agreement with Wyeth related to the manufacture, supply, inventory, and allocation of supplies of ENBREL®.

      Amgen and Wyeth have a long-term supply agreement with BI Pharma to manufacture commercial quantities of ENBREL®. In 2000 and 2002, the long-term supply agreement was amended to provide for additional production capacity, improved manufacturing processes, and to extend the term of the agreement.

      Amgen’s supply of ENBREL® is significantly dependent on product manufactured by BI Pharma, and, accordingly, Amgen has made significant purchase commitments to BI Pharma (see “MD&A — Contractual obligations”). Under the supply agreement, BI Pharma has reserved a specified level of production capacity for ENBREL®, and Amgen’s purchase commitments for ENBREL® are manufactured from that reserved production capacity. Amgen is required to submit a rolling three-year forecast for manufacturing the bulk drug for ENBREL®, and a rolling forecast for a shorter period for the number of finished vials of ENBREL® to be manufactured from the bulk drug. Amgen has submitted firm orders for the maximum production capacity that BI Pharma currently has reserved for ENBREL®. Amgen will be responsible for substantial payments to BI Pharma if Amgen fails to use a specified percentage of the production capacity that BI Pharma has reserved for ENBREL® each calendar year or if the BI Pharma supply agreement is terminated prematurely under specified conditions.

      The Company has a manufacturing agreement with Genentech, Inc. (“Genentech”) to produce ENBREL® at Genentech’s manufacturing facility in South San Francisco, California. The manufacturing facility is subject to FDA approval. If approved, the Genentech facility will become a licensed manufacturing site for commercial supply of ENBREL®. Under the terms of the agreement, Genentech will produce ENBREL® through 2005, with an extension through 2006 by mutual agreement.

      In October 2003, Amgen and Abgenix amended an existing agreement to jointly develop and commercialize panitumumab, a fully human monoclonal antibody created by Abgenix (See “Selected Product Candidates — Oncology). Under the amended agreement, Amgen has decision-making authority for the joint development and commercialization of panitumumab, but development and commercialization costs, as well as any potential profits from future sales of panitumumab, are shared equally. Amgen has the right to conduct all future clinical trials. In addition, Abgenix will manufacture clinical and early commercial supplies of panitumumab with Amgen’s support and assistance. If clinical trials for panitumumab are successful and regulatory approval is received, Amgen would play the primary role in implementing marketing and product launch activities for panitumumab, while Abgenix may participate in co-promotion.

      Amgen has agreed to advance Abgenix certain amounts that may be used by Abgenix to fund its share of development and commercialization costs for panitumumab. Abgenix is not obligated to repay such advances if panitumumab does not reach commercialization. As of December 31, 2003, no amounts have been advanced.

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      In May 2003, the Company entered into an agreement with Tularik Inc. (“Tularik”) to collaborate on the discovery, development, and commercialization of therapeutics aimed at oncology targets. The terms of the agreement include milestones payable to Tularik upon the achievement of specified targets, committed research funding paid to Tularik over a five-year period, and royalties on net commercial sales of Company products resulting from the agreement.

      As part of the agreement, the Company purchased shares of Tularik common stock and is required to purchase additional shares of newly-issued Tularik common stock over the next three years at the then market price. The Company accounts for its investment in Tularik common stock under the equity method (see Note 1, “Summary of significant accounting policies — Principles of consolidation” to the Consolidated Financial Statements).

      In September 2003, the Company entered into an agreement under which the Company received exclusive rights to develop and commercialize certain of Biovitrum’s small molecules for the treatment of metabolic diseases and certain other medical disorders. Under the agreement, the Company will fund and conduct all further development and commercialization activities relating to the licensed small molecules in the licensed territory, as defined; make milestone payments to Biovitrum upon achievement of certain specified targets including those related to development and regulatory submissions and approvals; pay tiered royalties to Biovitrum on future sales of all products arising from the agreement; and fund a three-year research program conducted by Biovitrum to develop additional compounds from the licensed small molecules.

Marketing

      Amgen maintains a sales and marketing force in the United States, Europe, Canada, Australia, and New Zealand. The Company’s sales force markets EPOGEN®, Aranesp®, Neulasta®, NEUPOGEN®, ENBREL®, and other products to healthcare providers including clinics, hospitals, and pharmacies. The Company also markets certain products directly to consumers through direct-to-consumer print and television advertising. In addition, Amgen has entered into licensing and/or co-promotion agreements to market certain of its products including Aranesp®, Neulasta®, and NEUPOGEN® in certain geographic areas outside of the United States. Under a co-promotion agreement with Wyeth, Amgen and Wyeth market ENBREL® in the United States and Canada for all approved indications other than oncology. The rights to develop and promote ENBREL® in the United States and Canada for oncology indications are reserved to Amgen.

      In the United States, the Company sells primarily to wholesale distributors of pharmaceutical products. With the exception of ENBREL®, the Company utilizes these wholesale distributors as the principal means of distributing the Company’s products to healthcare providers such as clinics, hospitals, and pharmacies. With respect to ENBREL®, the Company primarily drop-ships wholesaler orders directly to pharmacies for end-users. The Company monitors the financial condition of its larger distributors and limits its credit exposure by setting appropriate credit limits and requiring collateral from certain customers. Sales to three large wholesalers each accounted for more than 10% of total revenues for the years ended December 31, 2003, 2002, and 2001. Sales to AmerisourceBergen Corporation were $2,686.2 million, $2,084.4 million, and $1,470.1 million for the years ended December 31, 2003, 2002, and 2001, respectively. Sales to Cardinal Distribution were $1,596.2 million, $988.6 million, and $535.8 million for the years ended December 31, 2003, 2002, and 2001, respectively. Sales to McKesson Corporation were $1,340.4 million, $843.9 million, and $459.8 million for the years ended December 31, 2003, 2002, and 2001, respectively. Outside the United States, Aranesp®, Neulasta®, and NEUPOGEN® are principally distributed to hospitals and/or wholesalers depending upon the distribution practice in each country for which the product has been launched.

      Amgen was granted exclusive licenses by KA to market: 1) erythropoietin in the United States, 2) darbepoetin alfa in the United States, all European counties, Canada, Australia, New Zealand, Mexico, all Central and South American countries, and certain countries in Central Asia, North Africa, and the Middle

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      In the United States, dialysis providers are primarily reimbursed for EPOGEN® by the federal government through the End Stage Renal Disease Program (“ESRD Program”) of Medicare. The ESRD Program reimburses approved providers for 80% of allowed dialysis costs; the remainder is paid by other sources, including Medicaid, private insurance, and to a lesser extent, state kidney patient programs. The ESRD Program reimbursement rate is established by Congress and is monitored by the Centers for Medicare & Medicaid Services (“CMS”). Most patients receiving Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL® for approved indications are covered by both government and private payors health care programs. Therefore, sales of Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL® are dependent on the availability and extent of reimbursement from third-party payors, including governments and private insurance plans. Primary reimbursement for ENBREL® is obtained from private payors. Generally, worldwide use of our products may be affected by cost containment pressures from governments and private insurers on health care providers in response to ongoing initiatives to reduce health care expenditures, and to a lesser extent, competition (see “MD&A — Financial Outlook — Forward looking statements and factors that may affect Amgen — Our sales depend on payment and reimbursement from third-party payors, and a reduction in the payment rate or reimbursement could result in decreased use or sales of our products.”).

Competition

      Competition among biotechnology, pharmaceutical, and other companies that research, develop, manufacture, or market biologics and pharmaceuticals is intense and is expected to increase (see “MD&A — Financial Outlook — Forward looking statements and factors that may affect Amgen — Our marketed products face substantial competition and others may discover, develop, acquire or commercialize products before or more successfully than we do”). Some competitors, principally large pharmaceutical companies, have greater clinical, research, regulatory, and marketing resources and experience than Amgen, particularly in the area of small molecule therapeutics. In addition, certain specialized biotechnology firms have entered into cooperative arrangements with major companies for the development and commercialization of products, creating an additional source of competition. The Company faces product competition from firms in the United States, Europe, Canada, Australia, and elsewhere. Additionally, some of the Company’s competitors, including both biotechnology and pharmaceutical companies, are actively engaged in R&D in areas where the Company is also developing product candidates, as more fully discussed below.

      The introduction of new products or the development of new processes by competitors or new information about existing products may result in product replacements or price reductions, even for products protected by patents. In addition, the timing of entry of a new product into the market can be an important factor in determining the product’s eventual success and profitability. Early entry may have important advantages in gaining product acceptance and market share. Accordingly, in some cases, the relative speed with which the Company can develop products, complete the testing, receive approval, and supply commercial quantities of the product to the market is expected to be important to Amgen’s competitive position. Competition among biologic and pharmaceutical products approved for sale also may be based on, among other things, patent position, product efficacy, safety, reliability, availability, and price, as well as, the development and marketing of new competitive products.

      The Company’s European patent relating to erythropoietin expires on December 12, 2004. After such expiration of patent protection, other companies could develop and market new competitive products. While the Company does not market erythropoietin in Europe as this right belongs to Johnson & Johnson (through KA), the Company does market Aranesp® in the EU which competes with Johnson & Johnson’s and others’ erythropoietin products. In addition, the European patent relating to G-CSF expires on August 22, 2006. After

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      A significant amount of R&D in the biotechnology industry is conducted by small companies, academic institutions, governmental agencies, and other public and private research organizations. These entities may seek patent protection and enter into licensing arrangements to collect royalties for use of technology or for the sale of products they have discovered or developed. Amgen also may face competition in its licensing or acquisition activities from pharmaceutical companies and large biotechnology companies that also seek to acquire technologies or product candidates from these entities. Accordingly, the Company may have difficulty acquiring technologies or product candidates on acceptable terms. Additionally, the Company competes with these entities and with pharmaceutical and biotechnology companies to attract and retain qualified scientific and technical personnel.

      Any products or technologies that are directly or indirectly successful in addressing anemia could negatively impact the market for EPOGEN® and Aranesp®. Aranesp® directly competes with other currently marketed products which treat anemia, including EPOGEN® and the recombinant human erythropoietin product marketed by Johnson & Johnson (see “Products — EPOGEN® (Epoetin alfa)” and “Products — Aranesp® (darbepoetin alfa)”). Aventis Pharmaceuticals Inc. (“Aventis”) is developing gene-activated erythropoietin for the treatment of anemia (see “Item 3. Legal Proceedings — Transkaryotic Therapies and Aventis litigation”). Baxter International Inc. (“Baxter”) is developing epoetin omega for the treatment of anemia. Roche is developing a pegylated erythropoietin product for the treatment of anemia.

      Any products or technologies that are directly or indirectly successful in addressing anemia associated with chemotherapy could negatively impact the market for Aranesp®. In the United States, Aranesp® directly competes with other currently marketed products which treat anemia associated with chemotherapy, including the recombinant human erythropoietin product marketed by Johnson & Johnson (see “Products — EPOGEN® (Epoetin alfa)”). In Europe, Aranesp® directly competes with other erythropoietin products marketed by Ortho Biotech/Janssen-Cilag/Johnson & Johnson and Roche in the oncology setting. Aventis is also developing its gene-activated erythropoietin for the treatment of anemia (see “Item 3. Legal Proceedings — Transkaryotic Therapies and Aventis litigation”). Baxter and Roche are also developing their products for the treatment of anemia in the oncology setting.

      Any products or technologies that are directly or indirectly successful in addressing neutropenia associated with chemotherapy could negatively impact the markets for NEUPOGEN® and Neulasta®. NEUPOGEN® and Neulasta® currently face market competition from a competing CSF product, granulocyte macrophage colony stimulating factor (“GM-CSF”), and from the chemoprotectant, amifostine. Potential future sources of competition include other G-CSF products, GM-CSF products, among others. Neulasta® impacts NEUPOGEN® sales as health care providers in the United States transition from administering NEUPOGEN® to Neulasta®. Since the U.S. launch of Neulasta® in April 2002, NEUPOGEN® patients have been converting to Neulasta®. While the Company believes that most of the conversion has occurred, there is still some opportunity for this to continue into the future, albeit at a much slower rate, negatively impacting future NEUPOGEN® sales (see “MD&A — Financial Outlook — Trends expected to impact future operations”).

      Chugai Pharmaceuticals Co., Ltd. (“Chugai”) markets a G-CSF product in Japan as an adjunct to chemotherapy and as a treatment for bone marrow transplant (“BMT”) patients. Chugai and Aventis market a G-CSF product in certain EU countries as an adjunct to chemotherapy and as a treatment in BMT settings. Chugai, through its licensee, AMRAD, markets this G-CSF product in Australia as an adjunct to

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      Berlex Laboratories, Inc., a division of Schering (“Berlex”) markets GM-CSF under the trademark Leukine® in the United States for BMT and PBPC transplant patients and as an adjunct to chemotherapy treatments for acute non-lymphocytic leukemia (“ANLL”) and AML. Berlex is also pursuing other indications for its GM-CSF product including as an adjunct to chemotherapy outside the limited settings of ANLL and AML. Novartis AG (“Novartis”) markets another GM-CSF product for use in BMT patients and as an adjunct to chemotherapy in Europe and certain other countries. This GM-CSF product is currently being developed for similar indications in the United States and Canada. Nartograstim, a modified G-CSF protein, is sold by Kyowa Hakko Kogyo Co., Ltd. in Japan.

      Many companies are developing products that promote wound healing, soft tissue regeneration, and chemoprotection. Companies such as Genetics Institute, Inc., MedImmune, Inc., and IntraBiotics Pharmaceuticals, Inc. are currently among many companies that are developing products, which could be potential competitors for palifermin.

      Currently solid tumors are treated primarily with surgery, chemotherapy and/or radiotherapy depending upon tumor type, stage of disease, and the status of the patients. The panitumumab program could face competition from products under development or approved by Astra-Zeneca, Imclone Systems Inc./Bristol Myers Squibb Co./ Merck KgA, OSI/Genentech/Roche, Pfizer Inc. (“Pfizer”), and GlaxoSmithKline plc (“GlaxoSmithKline”).

      AMG 162 could face competition from products currently marketed by Novartis and Merck & Co., Inc. (“Merck”) for osteoporosis and a product currently marketed by Novartis for the treatment of cancer metastases to the bone.

      ENBREL® and PEG-sTNF-R1 could face competition in some circumstances from a number of companies developing or marketing rheumatoid arthritis and psoriatic arthritis treatments. Current anti-arthritic treatments include generic methotrexate and other products marketed by, among others, Centocor, Inc./Johnson & Johnson, Abbott Laboratories (“Abbott”), Merck, Pfizer, Novartis, Aventis, and Sanofi-Synthélabo. In addition, a number of companies have cytokine inhibitors in development including GlaxoSmithKline, Pfizer, and Taisho Pharmaceutical Co., Ltd. Amgen is currently developing ENBREL® for the treatment of psoriasis. If ENBREL® is approved for this indication, it may compete with products marketed by Biogen, Genentech, and Johnson & Johnson.

      Sensipar^TM could face competition from products currently marketed by Abbott, Bone Care International, Inc., Genzyme Corporation, and Roche which treat secondary HPT. In addition, another product to treat HPT is currently being developed by Chugai.

      The GDNF program could face competition from a deep brain stimulation device currently marketed by Medtronic Inc.

Research and Development

      Amgen’s product candidates (See — “Selected Product Candidates”) come from internal research, acquisitions, and licensing from third parties. The Company has research facilities in the United States, and has clinical development staff in the United States, Europe, Canada, Australia, and Japan (see “Item 2. Properties”). Amgen’s internal research capabilities include an expertise in secreted protein therapeutics. The Company’s discovery program may yield targets that lead to the development of therapeutics delivered as proteins, small molecules, or monoclonal antibodies. In addition, the acquisition of Immunex

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Government Regulation

      Regulation by governmental authorities in the United States and other countries is a significant factor in the production and marketing of the Company’s products and its ongoing R&D activities (see “MD&A — Financial Outlook — Forward looking statements and factors that may affect Amgen — Our current products and products in development cannot be sold if we do not obtain and maintain regulatory approval”).

      In order to clinically test, manufacture, and market products for therapeutic use, Amgen must satisfy mandatory procedures and safety and effectiveness standards established by various regulatory bodies. In the United States, the Public Health Service Act and the Federal Food, Drug, and Cosmetic Act, as amended, and the regulations promulgated there under, and other federal and state statutes and regulations govern, among other things, the testing, manufacture, labeling, storage, record keeping, approval, advertising, and promotion of the Company’s products on a product-by-product basis. Product development and approval within this regulatory framework takes a number of years and involves the expenditure of substantial resources. After laboratory analysis and preclinical testing in animals, an investigational new drug application is filed with the FDA to begin human testing. Typically, a three-phase human clinical testing program is then undertaken. In phase 1, small clinical trials are conducted to determine the safety of the product. In phase 2, clinical trials are conducted to assess safety, acceptable dose, and gain preliminary evidence of the efficacy of the product. In phase 3, clinical trials are conducted to provide sufficient data for the statistically valid proof of safety and efficacy. The time and expense required to perform this clinical testing can vary and is substantial. No action can be taken to market any new drug or biologic product in the United States until an appropriate marketing application has been approved by the FDA. Even after initial FDA approval has been obtained, further clinical trials may be required to provide additional data on safety and effectiveness and are required to gain clearance for the use of a product as a treatment for indications other than those initially approved. In addition, side effects or adverse events that are reported during clinical trials can delay, impede, or prevent marketing approval. Similarly, adverse events that are reported after marketing approval can result in additional limitations being placed on the product’s use and, potentially, withdrawal of the product from the market. Any adverse event, either before or after marketing approval, can result in product liability claims against the Company.

      In addition to regulating and auditing human clinical trials, the FDA regulates and inspects equipment, facilities, and processes used in the manufacturing and testing of such products prior to providing approval to market a product. If after receiving clearance from the FDA, a material change is made in manufacturing equipment, location, or process, additional regulatory review may be required. The Company also must adhere to current Good Manufacturing Practice and product-specific regulations enforced by the FDA through its facilities inspection program. The FDA also conducts regular, periodic visits to re-inspect equipment, facilities, laboratories, and processes following the initial approval. If, as a result of these inspections, the FDA determines that the Company’s equipment, facilities, laboratories, or processes do not comply with applicable FDA regulations and conditions of product approval, the FDA may seek civil, criminal, or administrative sanctions and/or remedies against Amgen, including the suspension of the Company’s manufacturing operations.

      In the European countries, Canada, and Australia, regulatory requirements and approval processes are similar in principle to those in the United States. Additionally, depending on the type of drug for which approval is sought, there are currently two potential tracks for marketing approval in the European countries: mutual recognition and the centralized procedure. These review mechanisms may ultimately lead to approval in all EU countries, but each method grants all participating countries some decision-making authority in product approval.

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      The Company is also subject to various federal and state laws pertaining to health care “fraud and abuse,” including anti-kickback laws and false claims laws. Anti-kickback laws make it illegal for a prescription drug manufacturer to solicit, offer, receive, or pay any remuneration in exchange for, or to induce, the referral of business, including the purchase or prescription of a particular drug. The federal government has published regulations that identify “safe harbors” or exemptions for certain payment arrangements that do not violate the anti-kickback statutes. The Company seeks to comply with the safe harbors where possible. Due to the breadth of the statutory provisions and the absence of guidance in the form of regulations or court decisions addressing some of the Company’s practices, it is possible that the Company’s practices might be challenged under anti-kickback or similar laws. False claims laws prohibit anyone from knowingly and willingly presenting, or causing to be presented for payment to third party payors (including Medicare and Medicaid) claims for reimbursed drugs or services that are false or fraudulent, claims for items or services not provided as claimed, or claims for medically unnecessary items or services. Amgen’s activities relating to the sale and marketing of its products may be subject to scrutiny under these laws. Violations of fraud and abuse laws may be punishable by criminal and/or civil sanctions, including fines and civil monetary penalties, as well as the possibility of exclusion from federal health care programs (including Medicare and Medicaid). If the government were to allege against or convict the Company of violating these laws, there could be a material adverse effect on the Company, including its stock price. The Company’s activities could be subject to challenge for the reasons discussed above and due to the broad scope of these laws and the increasing attention being given to them by law enforcement authorities.

      Since 1991, the Company has participated in the Medicaid rebate program established by the Omnibus Budget Reconciliation Act of 1990, and under amendments of that law that became effective in 1993. Participation in this program has included extending comparable discounts under the Public Health Service (“PHS”) pharmaceutical pricing program. Under the Medicaid rebate program, the Company pays a rebate for each unit of its product reimbursed by Medicaid. The amount of the rebate for each product is set by law as a minimum 15.1% of the average manufacturer price (“AMP”) of that product, or if it is greater, the difference between AMP and the best price available from the Company to any customer. The rebate amount also includes an inflation adjustment if AMP increases faster than inflation. The PHS pricing program extends discounts comparable to the Medicaid rebate to a variety of community health clinics and other entities that receive health services grants from the PHS, as well as hospitals that serve a disproportionate share of poor Medicare and Medicaid beneficiaries. The rebate amount is recomputed each quarter based on the Company’s reports of its current AMP and best price for each of its products to the CMS. The terms of the Company’s participation in the program impose an obligation to correct the prices reported in previous quarters, as may be necessary. Any such corrections could result in an overage or underage in the Company’s rebate liability for past quarters, depending on the direction of the correction. In addition to retroactive rebates (and interest, if any), if the Company were found to have knowingly submitted false information to the government, in addition to other penalties available to the government, the statute provides for civil monetary penalties in the amount of $100,000 per item of false information.

      The Company also makes its products available to authorized users of the Federal Supply Schedule (“FSS”) of the General Services Administration. Since 1993, as a result of the Veterans Health Care Act of 1992 (the “VHC Act”), federal law has required that product prices for purchases by the Veterans Administration, the Department of Defense, Coast Guard, and the PHS (including the Indian Health Service) be discounted by a minimum of 24% off the AMP to non-federal customers (the non-federal average manufacturer price, “non-FAMP”). The Company’s computation and report of non-FAMP is used in establishing the price, and the accuracy of the reported non-FAMP may be audited by the government under applicable federal procurement laws. Among the remedies available to the government for infractions of these laws is recoupment of any overages paid by FSS users during the audited years. In addition, if the Company were found to have knowingly reported a false non-FAMP, the VHC Act provides for civil monetary penalties of $100,000 per item that is incorrect.

      Amgen is also subject to regulation under the Occupational Safety and Health Act, the Toxic Substances Control Act, the Resource Conservation and Recovery Act, and other current and potential future federal, state, or local regulations. The Company’s R&D activities involve the controlled use of hazardous materials,

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      Additionally, the U.S. Foreign Corrupt Practices Act, to which the Company is subject, prohibits corporations and individuals from engaging in certain activities to obtain or retain business or to influence a person working in an official capacity. It is illegal to pay, offer to pay, or authorize the payment of anything of value to any foreign government official, government staff member, political party, or political candidate in an attempt to obtain or retain business or to otherwise influence a person working in an official capacity. The Company’s present and future business has been and will continue to be subject to various other laws and regulations.

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Patents and Trademarks

      The company has filed applications for a number of patents, has been granted patents, or has obtained rights relating to its products and various potential products. The material patents of the Company are set forth in the table below.

(1)	In some cases these European patents may also be entitled to Supplemental Protection in one or more countries in Europe and the length of any such extension will vary country by country.

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      There can be no assurance that Amgen’s patents or licensed patents will afford legal protection against competitors or provide significant proprietary protection or competitive advantage. In addition, Amgen’s patents or licensed patents could be held invalid or unenforceable by a court, or infringed or circumvented by others, or others could obtain patents that the Company would need to license or circumvent. Competitors or potential competitors may have filed patent applications or received patents, and may obtain additional patents and proprietary rights relating to proteins, small molecules, compounds, or processes competitive with those of the Company. Additionally, for certain of the Company’s product candidates, competitors, or potential competitors may claim that their existing or pending patents prevent the Company from commercializing such product candidates in certain territories. Further, when the Company’s patents expire, other companies could develop new competitive products to the Company’s products. The Company’s near-term European patent expirations could result in new competitive products to the Company’s products in Europe.

      In general, the Company has obtained licenses from various parties which it deems to be necessary or desirable for the manufacture, use or sale of its products. These licenses generally require Amgen to pay royalties to the parties on product sales. In addition, other companies have filed patent applications or have been granted patents in areas of interest to the Company. There can be no assurance any licenses required under such patents will be available for license on acceptable terms or at all. The Company is engaged in various legal proceedings relating to certain of its patents (see “Item 3. Legal Proceedings”).

      Trade secret protection for its unpatented confidential and proprietary information is important to Amgen. To protect its trade secrets, the Company generally requires its employees, material consultants, scientific advisors, and parties to collaboration and licensing agreements to execute confidentiality agreements upon the commencement of employment, the consulting relationship, or the collaboration or licensing arrangement with the Company. However, others could either develop independently the same or similar information or obtain access to Amgen’s information.

Manufacturing and Raw Materials

      Amgen has manufacturing facilities which produce commercial quantities of Epoetin alfa, Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL®. Amgen operates commercial manufacturing facilities located in the United States, Puerto Rico, and a packaging and distribution center in The Netherlands (see “Item 2. Properties”). Additional supply of ENBREL® is produced by our contract manufacturer. Additionally, the Company supplies Epoetin alfa in the United States to Johnson & Johnson under a supply agreement. There can be no assurance that the Company will be able to accurately anticipate future demand for Epoetin alfa, Aranesp®, Neulasta®, NEUPOGEN®, and ENBREL® or maintain adequate manufacturing capacity (see “MD&A — Financial Outlook — Forward looking statements and factors that may affect Amgen — We have grown rapidly, and if we fail to adequately manage that growth our business could be adversely impacted”).

      Amgen and Wyeth have a long-term supply agreement with BI Pharma to manufacture commercial quantities of ENBREL®. Amgen’s supply of ENBREL® is significantly dependent on product manufactured by BI Pharma (see “Joint Ventures and Business Relationships — Boehringer Ingelheim Pharma KG”). Amgen has made significant purchase commitments to BI Pharma under the BI Pharma supply agreement to manufacture commercial inventory of ENBREL®. Amgen has a large-scale biopharmaceutical manufacturing facility in West Greenwich, Rhode Island (the “RI Facility”). Amgen also utilizes third-party contract manufacturers to perform fill and finish services for ENBREL® manufactured at the RI Facility and packaging services for ENBREL® manufactured by BI Pharma and at the RI Facility.

      Certain raw materials, medical devices, and components necessary for the Company’s commercial manufacturing of its products are proprietary products of other companies, and in some cases, such proprietary products are specifically cited in the Company’s drug application with the FDA such that they must be obtained from that specific, sole source. The Company currently attempts to manage the risk associated with such sole sourced raw materials by active inventory management and alternate source development, where feasible (see “MD&A — Financial Outlook — Forward looking statements and factors that may affect Amgen — Certain of our raw materials, medical devices and components are single-sourced from third parties; third-party supply failures could adversely affect our ability to supply our products”). Amgen attempts

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Human Resources

      As of December 31, 2003, the Company had approximately 12,900 employ