Seattle Genetics Announces Initiation of SGN-40 Phase Ib Clinical Trial in Combination With Velcade for Multiple Myeloma

Seattle Genetics, Inc. (Nasdaq:SGEN) announced today that its collaborator, Genentech, Inc., has initiated a phase Ib clinical trial of SGN-40 in combination with Velcade® (bortezomib) for patients with relapsed or refractory multiple myeloma. This is the sixth ongoing clinical trial to evaluate SGN-40 either as a single agent or in combination with standard therapies for non-Hodgkin lymphoma and multiple myeloma. "Recent approvals of new multiple myeloma therapies, including Velcade, have extended median survival for patients, yet it remains an incurable disease,” said Thomas C. Reynolds, M.D., Ph.D., Chief Medical Officer of Seattle Genetics. "This trial is designed to evaluate the safety, tolerability and preliminary activity of the combination of SGN-40 and Velcade, towards the goal of identifying a therapeutic regimen that addresses the significant unmet medical need for these patients.” The American Cancer Society estimates that approximately 19,900 cases of multiple myeloma will be diagnosed in the United States during 2008, and approximately 10,700 people will die from the disease. The phase Ib open-label single-arm clinical trial will enroll up to approximately 30 patients with relapsed or refractory multiple myeloma at multiple cancer centers in the United States and Europe. Patients will receive escalating doses of SGN-40 in combination with a standard dose of Velcade. The study will assess safety and tolerability of the combination, pharmacokinetics and preliminary activity. SGN-40 Development Program SGN-40 is a humanized monoclonal antibody that is currently in phase Ib-IIb clinical trials for non-Hodgkin lymphoma and multiple myeloma under a worldwide collaboration agreement with Genentech. SGN-40 targets the CD40 antigen, which is expressed on most B lineage hematologic malignancies, as well as some solid tumors. Seattle Genetics and Genentech are conducting a joint development plan that includes six clinical trials of SGN-40 for the treatment of non-Hodgkin lymphoma and multiple myeloma. In addition to the SGN-40 plus Velcade study in multiple myeloma, the ongoing trials of SGN-40 include a phase II single-agent study in diffuse large B-cell lymphoma (DLBCL), a phase IIb study in combination with R-ICE (Rituxan, ifosfamide, carboplatin and etoposide) for DLBCL (SeaGen MARINER trial), a phase Ib study in combination with Rituxan and Gemzar in DLBCL, a phase Ib study in combination with Rituxan for follicular and marginal zone non-Hodgkin lymphoma and a phase Ib study in combination with Revlimid® (lenalidomide) for multiple myeloma. Under the terms of the collaboration agreement with Genentech, Seattle Genetics received an upfront payment of $60 million in February 2007, and is entitled to receive potential milestone payments exceeding $800 million and escalating double-digit royalties starting in the mid-teens on sales of SGN-40. Seattle Genetics also has an option to co-promote SGN-40 in the United States. To date, Seattle Genetics has received a total of $20 million in milestone payments from Genentech associated with SGN-40 clinical trial initiations. In addition, Genentech funds research, development, manufacturing and commercialization expenses for SGN-40, including reimbursing Seattle Genetics for costs incurred in connection with activities it performs under the collaboration. About Multiple Myeloma Multiple myeloma is a cancer of plasma cells, a type of white blood cell found primarily in the bone marrow. In multiple myeloma, malignant plasma cells grow continuously, destroying normal bone tissue and crowding out normal blood cell production. Multiple myeloma is an incurable disease in which patients can experience symptoms that significantly impact their quality of life, including pain, anemia, fatigue, recurrent infection and kidney failure. SGN-40 has received orphan drug designation from the FDA for the treatment of multiple myeloma. 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-40. 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 the inability to show sufficient safety or activity in this phase I clinical trial and the risk of adverse clinical results as SGN-40 advances in clinical trials. 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.