SGEN

Seattle Genetics, Inc.

Seattle Genetics is a clinical stage biotechnology company focused on the development and commercialization of monoclonal antibody-based therapies for the treatment of cancer and autoimmune disease. We initiated a pivotal trial of our lead product candidate, SGN-35, during the first quarter of 2009 for patients with relapsed or refractory Hodgkin lymphoma under a special protocol assessment, or SPA, with the U.S. Food and Drug Administration, or FDA. SGN-35 is empowered by our proprietary antibody-drug conjugate, or ADC, technology comprising highly potent synthetic drugs and stable linkers for attaching the drugs to monoclonal antibodies. In addition, we have three other product candidates in ongoing clinical trials: dacetuzumab (SGN-40), lintuzumab (SGN-33) and SGN-70. Dacetuzumab is being developed under a worldwide collaboration with Genentech, Inc.

We have collaborations for our ADC technology with a number of leading biotechnology and pharmaceutical companies, including Genentech, Inc., Bayer Pharmaceuticals Corporation, CuraGen Corporation, Progenics Pharmaceuticals, Inc., Daiichi Sankyo Co., Ltd. and MedImmune, Inc., a subsidiary of AstraZeneca, Inc., as well as an ADC co-development agreement with Agensys, Inc., a subsidiary of Astellas Pharma, Inc.

We do not currently have any commercial products for sale. While certain of our product candidates are advancing into later stages of development, such as SGN-35, significant further research and development, financial resources and personnel will be required to develop commercially viable products and obtain regulatory approvals. As of December 31, 2008, we had an accumulated deficit of $314.0 million. Over the next several years, we expect that we will incur substantial expenses, primarily the result of activities related to the potential regulatory approval and commercialization of SGN-35, including preparation for commercial manufacturing. We will also continue to invest in research, development and manufacturing and move towards potential commercialization of our other product candidates. Our commitment of resources to the approval and commercialization activities for SGN-35 and the research and continued development and potential commercialization of our other product candidates will require substantial additional funds and resources and our operating expenses will also likely increase as a result of such activities. In addition, we may incur significant milestone payment obligations as our product candidates progress through clinical trials towards potential commercialization. We expect that a substantial portion of our revenues for the next several years will be the result of amortization of payments already received and expected to be received from Genentech under our dacetuzumab collaboration agreement. Until such time as we have commercialized a product candidate, our revenues will also depend on the achievement of development and clinical milestones under our existing collaboration and license agreements, particularly our dacetuzumab collaboration with Genentech, as well as entering into new collaboration and license agreements. Our results of operations may vary substantially from year to year and from quarter to quarter and, as a result, we believe that period to period comparisons of our operating results may not be meaningful and you should not rely on them as indicative of our future performance.

As of December 31, 2008, we had 261 employees. Of these employees, 218 are engaged in or support research, development and clinical activities and 43 are in administrative and business related positions. Each of our employees has signed confidentiality and inventions assignment agreements and none are covered by a collective bargaining agreement. We have never experienced employment-related work stoppages and consider our employee relations to be good.

We were incorporated in Delaware on July 15, 1997. Our principal executive offices are located at 21823 30th Drive SE, Bothell, Washington 98021. Our telephone number is (425) 527-4000. Seattle Genetics® and LOGO are our registered trademarks in the United States. All other trademarks, tradenames and service marks included in this Annual Report on Form 10-K are the property of their respective owners.

We file electronically with the Securities and Exchange Commission our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934. We make available on our website at www.seattlegenetics.com, free of charge, through a hyperlink on our website, copies of these reports, as soon as reasonably practicable after electronically filing such reports with, or furnishing them to, the Securities and Exchange Commission.