Seattle Genetics, Inc. (Nasdaq: SGEN) today announced that SGN-35 will be highlighted in an oral presentation during a plenary session on Saturday, June 7, 2008 at the International Conference on Malignant Lymphoma (ICML) being held in Lugano, Switzerland.

In a phase I dose-escalation trial of SGN-35, multiple patients with Hodgkin lymphoma and other CD30-positive hematologic malignancies achieved objective responses, including five complete responses and seven partial responses. At doses at or above 1.2 milligrams per kilogram, 45 percent of evaluable patients achieved objective responses. Additionally, 81 percent of patients who had at least one post-baseline assessment achieved reductions in tumor volume. The SGN-35 oral presentation includes data reported in a poster discussion session during the recent American Society of Clinical Oncology (ASCO) annual meeting.

SGN-35 is an antibody-drug conjugate (ADC) comprising an anti-CD30 antibody attached by an enzyme cleavable linker to a potent, synthetic drug payload, monomethyl auristatin E (MMAE), using Seattle Genetics™ proprietary technology. The ADC is designed to be stable in the bloodstream, but to release MMAE upon internalization into CD30-expressing tumor cells, resulting in a targeted cell-killing effect.

A downloadable copy of the SGN-35 presentation will be available following the ICML plenary session from the Technology section of the company™s website at The SGN-35 ASCO poster presentation is also available on the company™s website.

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 has a worldwide collaboration with Genentech for SGN-40. Seattle Genetics also has two other product candidates in ongoing clinical trials: SGN-33 and SGN-35. In addition, the company has developed proprietary antibody-drug conjugate (ADC) technology comprising highly potent synthetic drugs and stable linkers for attaching the drugs to monoclonal antibodies. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including Genentech, Bayer, CuraGen, Progenics and MedImmune, a wholly owned subsidiary of AstraZeneca, as well as an ADC co-development agreement with Agensys, a wholly owned subsidiary of Astellas Pharma.

Certain of the statements made in this press release are forward looking, such as those, among others, relating to the therapeutic potential of SGN-35. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include risks related to adverse clinical results as SGN-35 advances in clinical trials, such as patients exhibiting progressive disease or severe adverse events. More information about the risks and uncertainties faced by Seattle Genetics is contained in the company™s filings with the Securities and Exchange Commission. Seattle Genetics disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Seattle Genetics, Inc.
Peggy Pinkston, 425-527-4160