ImageSeattle Genetics, Inc, 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 US 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, 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 enrol patients at more than 30 sites in the US, 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 per cent with complete responses. Furthermore, 93 per cent of these patients achieved tumour 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.

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.