Amgen and Abgenix Complete Biologics License Application for FDA Approval of Panitumumab

"The pivotal Phase 3 study of panitumumab not only met the primaryendpoint of improving progression-free survival in patients withmetastatic colorectal cancer, but the results surpassed ourexpectations based on preset measurement criteria in the protocol,"said Willard Dere, M.D., chief medical officer and senior vicepresident of Global Development at Amgen. "Completing the BLA bringsus one step closer to realizing our goal of making panitumumabaccessible to patients with metastatic colorectal cancer who havefailed available treatment options."

Amgen and Abgenix previously announced that data from a randomizedPhase 3 trial involving 463 patients showed that those who receivedpanitumumab every two weeks showed a 46 percent decrease in tumorprogression rate versus those who received best supportive care alone(p less than 0.000 000 001). The most common side effect was acneiformrash. Other side effects less commonly observed were fatigue, nauseaand mild diarrhea.

Results from this pivotal Phase 3 study will be presented in aClinical Plenary Session at the 97th Annual Meeting of the AmericanAssociation for Cancer Research on April 3, 2006. Amgen will host awebcast with the investment community to discuss the results onMonday, April 3, 2006, at 12:30 P.M. EDT. Open to members of the newsmedia, investors and the general public, the webcast can be found onAmgen's Web site, www.amgen.com, under Investors. It will be archivedand available for replay at least 72 hours after the event.

About Panitumumab

Panitumumab is an investigational fully human monoclonal antibodythat targets the epidermal growth factor receptor (EGFr), a proteinthat plays an important role in cancer cell signaling. Panitumumab, anIgG2 monoclonal antibody, binds with high affinity to the EGFr.Panitumumab was generated with XenoMouse(R) technology, which createsa fully human monoclonal antibody that contains no murine (mouse)protein. The body's immune system can recognize the mouse proteinfound in chimeric and humanized antibodies as foreign and launch animmune response in the form of infusion reactions, allergic reactionsor anaphylaxis. The goal of developing fully human monoclonalantibodies is to offer effective, high affinity therapies thatminimize the potential for this type of immune response.

Panitumumab received Fast Track designation from the U.S. Food andDrug Administration (FDA) in July 2005 for patients with metastaticcolorectal cancer who have failed standard chemotherapy treatment. Itis being evaluated in clinical trials as both a monotherapy and incombination with other agents for the treatment of various types ofcancer, including colorectal, lung and head and neck.

About the Epidermal Growth Factor Receptor (EGFr)

Although EGFr normally helps regulate the growth of many differentcells in the body, EGFr also can stimulate cancer cells to grow. Infact, many cancer cells actually require signals mediated by EGFr fortheir survival. Residing on the surface of these tumor cells, EGFr isactivated when naturally occurring proteins in the body, such asepidermal growth factor (EGF) or transforming growth factor alpha(TGF-alpha), bind to it. This binding changes the shape of EGFr,which, in turn, triggers internal cellular signals that stimulatetumor cell growth. Panitumumab binds to EGFr, preventing the naturalligands such as EGF and TGF-alpha from binding to the receptor andinterfering with the signals that would otherwise stimulate growth ofthe cancer cell and allow it to survive.

About Colorectal Cancer

Colorectal cancer is the third most common cancer diagnosed in menand in women in the United States. The American Cancer Societyestimates that about 106,680 new cases of colon cancer and 41,930 newcases of rectal cancer will be diagnosed in 2006.

About Amgen

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

About Abgenix

Abgenix is a biopharmaceutical company focused on the discovery,development and manufacturing of fully human therapeutic antibodies.The company's antibody development platform includes a leadingtechnology and state-of-the-art manufacturing capabilities that enablethe rapid generation, selection and production of high affinity, fullyhuman antibody product candidates to a variety of disease targets.Abgenix leverages its leadership position in human antibody technologyto build a diversified product portfolio through its own developmentefforts and the establishment of collaborations with multiplepharmaceutical and biotechnology companies. For more information onAbgenix, visit the company's website at www.abgenix.com.

Amgen Forward-Looking Statement

This news release contains forward-looking statements that involvesignificant risks and uncertainties, including those discussed belowand others that can be found in Amgen's Form 10-K for the year endedDecember 31, 2005, and in Amgen's periodic reports on Form 10-Q andForm 8-K. Amgen is providing this information as of the date of thisnews release and does not undertake any obligation to update anyforward-looking statements contained in this document as a result ofnew information, future events or otherwise.

No forward-looking statement can be guaranteed and actual resultsmay differ materially from those Amgen projects. Discovery oridentification of new product candidates or development of newindications for existing products cannot be guaranteed and movementfrom concept to product is uncertain; consequently, there can be noguarantee that any particular product candidate or development of anew indication for an existing product will be successful and become acommercial product. Further, preclinical results do not guarantee safeand effective performance of product candidates in humans. Thecomplexity of the human body cannot be perfectly, or sometimes, evenadequately modeled by computer or cell culture systems or animalmodels. The length of time that it takes for Amgen to completeclinical trials and obtain regulatory approval for product marketinghas in the past varied and Amgen expects similar variability in thefuture. Amgen develops product candidates internally and throughlicensing collaborations, partnerships and joint ventures. Productcandidates that are derived from relationships may be subject todisputes between the parties or may prove to be not as effective or assafe as Amgen may have believed at the time of entering into suchrelationship. Also, Amgen or others could identify side effects ormanufacturing problems with Amgen's products after they are on themarket. In addition, sales of Amgen's products are affected by theavailability of reimbursement and the reimbursement policies imposedby third party payors, including governments, private insurance plansand managed care providers, and may be affected by domestic andinternational trends toward managed care and healthcare costcontainment as well as possible U.S. legislation affectingpharmaceutical pricing and reimbursement. Government regulations andreimbursement policies may affect the development, usage and pricingof Amgen's products. In addition, Amgen competes with other companieswith respect to some of Amgen's marketed products as well as for thediscovery and development of new products. Amgen believes that some ofthe newer products, product candidates or new indications for existingproducts, may face competition when and as they are approved andmarketed. Amgen products may compete against products that have lowerprices, established reimbursement, superior performance, are easier toadminister, or that are otherwise competitive with our products. Inaddition, while Amgen routinely obtains patents for Amgen's productsand technology, the protection offered by Amgen's patents and patentapplications may be challenged, invalidated or circumvented by Amgen'scompetitors and there can be no guarantee of Amgen's ability to obtainor maintain patent protection for Amgen's products or productcandidates. Amgen cannot guarantee that it will be able to producecommercially successful products or maintain the commercial success ofAmgen's existing products. Amgen's stock price may be affected byactual or perceived market opportunity, competitive position, andsuccess or failure of Amgen's products or product candidates. Further,the discovery of significant problems with a product similar to one ofAmgen's products that implicate an entire class of products could havea material adverse effect on sales of the affected products and onAmgen's business and results of operations.

The scientific information discussed in this news release relatedto our product candidates is preliminary and investigative. Suchproduct candidates are not approved by the U.S. Food and DrugAdministration (FDA), and no conclusions can or should be drawnregarding the safety or effectiveness of the product candidates. Onlythe FDA can determine whether the product candidates are safe andeffective for the use(s) being investigated. Further, the scientificinformation discussed in this news release relating to new indicationsfor our products is preliminary and investigative and is not part ofthe labeling approved by the FDA for the products. The products arenot approved for the investigational use(s) discussed in this newsrelease, and no conclusions can or should be drawn regarding thesafety or effectiveness of the products for these uses. Only the FDAcan determine whether the products are safe and effective for theseuses. Healthcare professionals should refer to and rely upon theFDA-approved labeling for the products, and not the informationdiscussed in this news release.

Abgenix Forward-Looking Statement

Statements made in this press release about Abgenix'stechnologies, product development activities, collaborativearrangements and the proposed merger with Amgen, other than statementsof historical fact, are forward-looking statements and are subject toa number of uncertainties that could cause actual results to differmaterially from the statements made. For example, statements regardingthe expected timing of the closing of the merger are forward-lookingstatements. Factors that could cause actual results to differmaterially from those contemplated above include, among others, therisks associated with the timing and success of clinical trials, theprogress of research and product development programs, productmanufacturing, consummating the merger with Amgen, timing and outcomesof regulatory approval processes, competitive products and services,litigation and the extent and breadth of Abgenix's patent portfolio.Please see Abgenix's public filings with the Securities and ExchangeCommission (SEC) for information about risks that may affect Abgenix,including its Form 10-K for the year ended December 31, 2005, andreports on Form 10-Q and Form 8-K.

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