Seattle Genetics to Host Conference Call on December 15, 2009, to Discuss Brentuximab Vedotin (SGN-35) Partnering

SEATTLE–(BUSINESS WIRE)– Seattle Genetics, Inc. (NASDAQ:SGEN), today announced that its management will host a teleconference at 5:30 a.m. Pacific Time (PT) / 8:30 a.m. Eastern Time (ET) on Tuesday, December 15, 2009, to discuss brentuximab vedotin (SGN-35) partnering. A press release with respect to brentuximab vedotin partnering will be issued prior to the teleconference. Brentuximab vedotin is an antibody-drug conjugate (ADC) targeting CD30 that is in clinical trials for the treatment of relapsed and refractory Hodgkin lymphoma (HL) and systemic anaplastic large cell lymphoma (ALCL).

The live event will be available from Seattle Genetics’ website at www.seattlegenetics.com, under the Investors and News section, or by calling 877-941-8632 (domestic) or 480-629-9821 (international). The access code is 4193888. A replay of the discussion will be available beginning at approximately 7:30 a.m. PT / 10:30 a.m. ET on December 15, 2009, from Seattle Genetics’ website or by calling 800-406-7325 (domestic) or 303-590-3030 (international), using access code 4193888.

About Seattle Genetics

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. The company’s lead product candidate, brentuximab vedotin, is in a pivotal trial under a special protocol assessment with the FDA. In addition, Seattle Genetics has four other product candidates in ongoing clinical trials: lintuzumab (SGN-33), dacetuzumab (SGN-40), SGN-70 and SGN-75. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including Genentech, Bayer, CuraGen, a subsidiary of Celldex Therapeutics, Progenics, Daiichi Sankyo, MedImmune, a subsidiary of AstraZeneca, and Millennium: The Takeda Oncology Company, as well as an ADC co-development agreement with Agensys, an affiliate of Astellas. More information can be found at www.seattlegenetics.com.