Seattle Genetics announced that it has initiated a pivotal trial of SGN-35 for patients with relapsed or refractory Hodgkin lymphoma

BOTHELL, WA, USA | February 19, 2009 | Seattle Genetics, Inc. (NASDAQ:SGEN), today announced that it has initiated a pivotal trial of SGN-35 for patients with relapsed or refractory Hodgkin lymphoma. The trial is being conducted under a Special Protocol Assessment (SPA), which is an agreement between the U.S. Food and Drug Administration (FDA) and Seattle Genetics regarding the trial design necessary to support an efficacy claim in a New Drug Application (NDA). SGN-35 is an antibody-drug conjugate (ADC) that utilizes Seattle Genetics’ proprietary technology to empower antibodies by linking them to potent cell-killing drugs.

“Through a combination of focused effort by our team and strong interest from investigators, we were able to treat our first patient in this pivotal trial within five weeks of receiving the SPA,” said Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. “We believe SGN-35 has a potentially rapid path to regulatory approval, and this pivotal trial is a significant step toward bringing this promising ADC to Hodgkin lymphoma patients in need of new and better treatments. Our goal is to submit the NDA in 2011 under the accelerated approval regulations.”

The single-arm pivotal trial will assess efficacy and safety of single-agent SGN-35 in 100 patients with relapsed or refractory Hodgkin lymphoma who previously received autologous stem cell transplant. Patients will receive 1.8 milligrams per kilogram (mg/kg) of SGN-35 every three weeks. The primary endpoint of the trial will be objective response rate assessed by an independent radiographic facility. Secondary endpoints include duration of response, progression-free survival, overall survival and tolerability. The company plans to enroll patients at more than 30 sites in the U.S., Canada and Europe.

In a phase I dose-escalation clinical trial of SGN-35, among 28 evaluable patients with relapsed or refractory Hodgkin lymphoma or systemic anaplastic large cell lymphoma (ALCL) treated at doses of 1.2 mg/kg and higher administered every three weeks, 54 percent achieved an objective response, including 32 percent with complete responses. Furthermore, 93 percent of these patients achieved tumor reductions and median progression-free survival was greater than six months. SGN-35 was generally well tolerated.

Seattle Genetics also plans to initiate a phase II study of single-agent SGN-35 in approximately 55 patients with relapsed or refractory systemic ALCL in the first quarter of 2009. In addition, the company is continuing dose escalation in an ongoing phase I clinical trial of SGN-35 administered on a weekly basis, and expects to report data from this trial during 2009.

About SGN-35

SGN-35 is an 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. SGN-35 has received orphan drug designation in the United States and Europe for both Hodgkin lymphoma and ALCL.

About Hodgkin Lymphoma

Lymphoma is a general term for a group of cancers that originate in the lymphatic system. There are two major categories of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma. Hodgkin lymphoma is distinguished from other types of lymphoma by the presence of one characteristic type of cell, known as the Reed-Sternberg cell. A defining attribute of the Reed-Sternberg cell is its expression of the CD30 antigen. Based on market research, Seattle Genetics believes that there are several thousand newly relapsed or refractory lymphoma patients in the United States each year who would be eligible for treatment with SGN-35, and that the U.S. prevalence population of these patients is approximately 10,000 individuals.

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’s lead product candidate, SGN-35, is in a pivotal trial under an SPA with the FDA. SGN-35 is empowered by Seattle Genetics’ proprietary antibody-drug conjugate (ADC) technology comprising highly potent synthetic drugs and stable linkers for attaching the drugs to monoclonal antibodies. In addition, Seattle Genetics has three other product candidates in ongoing clinical trials: dacetuzumab (SGN-40), lintuzumab (SGN-33) and SGN-70. Dacetuzumab is being developed under a worldwide collaboration with Genentech. Seattle Genetics has collaborations for its ADC technology with a number of leading biotechnology and pharmaceutical companies, including Genentech, Bayer, CuraGen, Progenics, Daiichi Sankyo and MedImmune, a subsidiary of AstraZeneca, as well as an ADC co-development agreement with Agensys, a subsidiary of Astellas Pharma. More information 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 potential therapeutic benefit, regulatory pathway, timelines and market 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, among others: that the company may experience delays in the initiation and/or completion of the clinical trials of SGN-35 in Hodgkin lymphoma and ALCL, whether caused by competition, adverse events, patient enrollment rates, regulatory issues or other factors; that the clinical trials, including the pivotal clinical trial for relapsed or refractory Hodgkin lymphoma, may not demonstrate that SGN-35 is both safe and effective; that data from our phase I clinical trials of SGN-35 may not necessarily be indicative of the subsequent clinical trial results, including our pivotal clinical trial results; and that the safety and/or efficacy results of these trials, including the SGN-35 pivotal clinical trial for relapsed or refractory Hodgkin lymphoma, will not support an application for marketing approval in the United States or any other country. 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.