BOTHELL, Wash.--(BUSINESS WIRE)--Jan. 22, 2004--Seattle Genetics, Inc. (Nasdaq:SGEN) announced today that it has initiated a phase II clinical trial of SGN-30, a monoclonal antibody for the treatment of hematologic malignancies. The study is designed to evaluate the antitumor activity and safety of SGN-30 in patients with Hodgkin's disease or anaplastic large cell lymphoma.

"SGN-30 represents a targeted approach to cancer therapy and may offer a much needed option for patients with advanced hematologic malignancies, where currently available treatments are limited and can cause toxic side effects," stated Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. "Initiating the phase II clinical trial is an important step toward our goal of developing antibody-based therapeutics for patients with cancer."

The single-agent, open label study will accrue up to a total of 80 patients, 40 per disease indication. The trial, which is being conducted at over 10 sites in the United States, is designed to assess the tolerability and antitumor activity of SGN-30 in patients who have relapsed or are refractory to prior therapies.

Seattle Genetics reported data from the phase I multi-dose clinical trial of SGN-30 at the American Society of Hematology annual meeting in December 2003. In the phase I study, 24 patients, in six-patient cohorts, received weekly infusions of SGN-30 at doses ranging from two to twelve milligrams per kilogram. SGN-30 was well tolerated and antitumor activity was observed. One patient with anaplastic large cell lymphoma demonstrated a complete response lasting at least four months and six of the 24 patients had stable disease.

SGN-30 is a genetically engineered monoclonal antibody that targets CD30-positive hematologic malignancies, including Hodgkin's disease and certain types of lymphomas and leukemias. In July 2003, the company received orphan drug designation from the FDA for SGN-30 in Hodgkin's disease. Additionally, Seattle Genetics is conducting preclinical studies to evaluate the potential of SGN-30 for the treatment of immunologic diseases.

About Seattle Genetics

Seattle Genetics discovers and develops monoclonal antibody-based therapeutics to treat cancer and other human diseases. The company has built a diverse portfolio of product candidates targeted to many types of cancer, including two being tested in multiple ongoing clinical trials, SGN-30 and SGN-15, and three in preclinical development, SGN-40, SGN-35 and SGN-17/19. The product candidates encompass three platform technologies: genetically engineered monoclonal antibodies, antibody-drug conjugates (ADCs) and antibody-directed enzyme prodrug therapy (ADEPT). Seattle Genetics has developed leading ADC technology comprised of highly potent drugs and stable linkers for attaching the drugs to monoclonal antibodies. The company currently has license agreements for its ADC technology with Genentech, Celltech Group and Protein Design Labs and for its ADEPT technology with Genencor International. More information about Seattle Genetics can be found at www.seattlegenetics.com.

Certain of the statements made in this press release are forward-looking, such as those, among others, relating to the therapeutic potential of SGN-30. 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 our product candidates move into and advance in clinical trials, risks inherent in early stage development and failure by Seattle Genetics to secure or maintain relationships with collaborators. 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.

CONTACT: Seattle Genetics, Inc.
Peggy Pinkston, 425-527-4160
ppinkston@seagen.com

SOURCE: Seattle Genetics, Inc.