Seattle Genetics Announces SGN-35 Plenary Presentation at International Conference...

Seattle Genetics Announces SGN-35 Plenary Presentation at International Conference on Malignant Lymphoma

SEATTLE--(Business Wire)--
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 www.seattlegenetics.com. 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
ppinkston@seagen.com

Copyright Business Wire 2008