Seattle Genetics, Inc. today announced final data from the phase I clinical trial of SGN-40 in patients with relapsed or refractory non-Hodgkin lymphoma

SEATTLE, WA, USA | June 5, 2008 | Seattle Genetics, Inc. (Nasdaq:SGEN) today announced final data from the phase I clinical trial of SGN-40 in patients with relapsed or refractory non-Hodgkin lymphoma. SGN-40 is a humanized monoclonal antibody being developed under a worldwide collaboration agreement with Genentech, Inc. Multiple objective responses were achieved and SGN-40 was generally well tolerated with no maximum tolerated dose identified. The data were reported during an oral presentation at the International Conference on Malignant Lymphoma (ICML) being held in Lugano, Switzerland.

"These data are encouraging considering that patients treated on this phase I clinical trial were heavily pretreated and had limited therapeutic options," said Thomas C. Reynolds, M.D., Ph.D., Chief Medical Officer of Seattle Genetics. "The data support our ongoing development plan with Genentech, which includes multiple clinical trials of SGN-40 both as a single agent and in combination with standard treatment regimens for patients with diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma."

SGN-40 Phase I Study Design and Results

Fifty patients with non-Hodgkin lymphoma were treated on the open label single-arm, dose-escalation study of SGN-40. Cohorts of patients received escalating doses of SGN-40 ranging from 2 milligrams per kilogram (mg/kg) to 8 mg/kg. The median age was 62 years and patients had received a median of 3 prior therapies.

Out of 48 patients treated with SGN-40 who were evaluable for response across all dose levels, six patients achieved objective responses, including one complete response and five partial responses. Thirteen patients had stable disease and 29 had progressive disease. Of the 22 patients on the trial with DLBCL, a more aggressive type of non-Hodgkin lymphoma, four achieved an objective response. It was also reported during the ICML presentation that two patients who experienced stable disease while on study subsequently achieved durable complete responses after withdrawal from the trial without receiving any subsequent therapy.

Overall, SGN-40 was well-tolerated. The majority of adverse events were Grade 1 and 2, including fatigue, fever and headache.

A downloadable copy of the ICML presentation will be available today from the "Technology" section of the company’s website at www.seattlegenetics.com.

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. The ongoing clinical trials of SGN-40 include a phase II single-agent study in DLBCL, a phase IIb study in combination with R-ICE (rituximab, ifosfamide, carboplatin and etoposide) for DLBCL (SeaGen MARINER trial), a phase Ib study in combination with rituximab and Gemzar(R) (gemcitabine) in DLBCL, a phase Ib study in combination with rituximab for follicular and marginal zone non-Hodgkin lymphoma, a phase Ib study in combination with Revlimid(R) (lenalidomide) and dexamethasone for multiple myeloma and a phase Ib trial in combination with Velcade(R) (bortezomib) 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 funds for the program.

About Non-Hodgkin Lymphoma

Non-Hodgkin lymphoma represents a diverse group of cancers that develop in the lymphatic system and are characterized by uncontrolled growth and accumulation of abnormal lymphocytes. Lymphocytes are a type of white blood cells that are responsible for defending the body against infection. The most common forms of non-Hodgkin lymphoma are follicular (slow growth) and DLBCL (a faster growing sub-type). According to the American Cancer Society, approximately 66,000 cases of non-Hodgkin lymphoma will be diagnosed in the United States during 2008, and an estimated 19,000 people will die of the disease.

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.

SOURCE: Seattle Genetics, Inc.