Seattle Genetics Receives $4.5 Million Payment from Genentech

BOTHELL, WA, USA | Mar 27, 2007 | Seattle Genetics, Inc. (Nasdaq:SGEN) today announced that Genentech, Inc. has paid $4.5 million to exercise exclusive licenses to specific targets and extend the research term under the parties’ existing antibody-drug conjugate (ADC) collaboration agreement. Under the terms of the agreement, Genentech has rights to use Seattle Genetics’ ADC technology with antibodies against targets selected by Genentech. Genentech is responsible for research, product development, manufacturing and commercialization activities under the collaboration. Seattle Genetics is entitled to receive fees, progress-dependent milestone payments and royalties on net sales of any resulting ADC products.

"Genentech’s exercise of exclusive licenses and extension of the research term strengthens our ADC collaboration, underscoring the therapeutic potential of this technology to empower monoclonal antibodies," said Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. "We have reported preclinical data demonstrating the stability of our linker systems and the potency of our synthetic auristatin drug payloads. Our lead proprietary ADC, SGN-35, is in a phase I clinical trial, and a number of our collaborators continue to make advances with their programs utilizing our technology."

Seattle Genetics has generated more than $55 million through technology-licensing transactions, primarily from its ADC deals with Genentech, CuraGen, Progenics, Bayer and MedImmune. The company also has a co-development agreement with Agensys under which the parties will develop up to two ADCs incorporating fully human antibodies provided by Agensys that are aimed at solid tumors.

ADCs utilize the targeting ability of monoclonal antibodies to deliver potent, cell-killing payloads to specific cells. Seattle Genetics has developed proprietary technology employing synthetic, highly potent drugs that can be attached to antibodies through proprietary linker systems. The linkers are designed to be stable in the bloodstream but to release the drug payload under specific conditions once inside target cells, thereby sparing non-target cells many of the toxic effects of traditional chemotherapy.

About Seattle Genetics

Seattle Genetics is a biotechnology company developing monoclonal antibody-based therapies for the treatment of multiple types of cancer, including lymphoma, multiple myeloma, leukemia and solid tumors. The company has an exclusive worldwide license agreement with Genentech to develop and commercialize SGN-40. In addition, Seattle Genetics has developed proprietary antibody-drug conjugate (ADC) technology comprised of highly potent synthetic drugs and stable linkers for attaching the drugs to monoclonal antibodies. The company has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including Genentech, Bayer, CuraGen, Progenics and MedImmune, as well as an ADC co-development agreement with Agensys. More information can be found at www.seattlegenetics.com.

Certain of the statements made in this press release are forward-looking. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Specifically, statements regarding the stability, safety, potency and therapeutic potential of antibody-drug conjugates are forward-looking and actual results may differ materially from these statements for various reasons. 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 our collaborators to perform their contractual obligations or advance products incorporating our technology. 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.

SOURCE: Seattle Genetics, Inc.