Seattle Genetics slumps on stopping dacetuzumab Phase IIb diffuse large B-cell lymphoma trial

US Washington State-based Seattle Genetics says its share price plunge, almost 20% at $10.71 in pre-market trading, after announcing that it has discontinued the SeaGen MARINER clinical trial based on a determination that it would be unlikely to meet its primary endpoint of superior complete response rate in the dacetuzumab combination arm as compared to the placebo combination cohort.

The SeaGen MARINER trial was a randomized, double-blind phase IIb clinical trial of dacetuzumab or placebo in combination with Rituxan (rituximab) plus ifosfamide, carboplatin and etoposide (R-ICE) chemotherapy for patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL). The trial was closed based upon a recommendation by the Independent Data Monitoring Committee following a pre-specified interim analysis conducted on October 2, 2009. As a result of the closure, dacetuzumab will no longer be provided to patients enrolled on the trial.

Seattle Genetics is developing dacetuzumab under a worldwide collaboration agreement with Genentech, a wholly owned member of the Roche Group. An oral presentation of a Phase Ib clinical trial evaluating dacetuzumab in combination with Rituxan and Gemzar (gemcitabine) will be made on December 7 at the American Society of Hematology annual meeting taking place in New Orleans, LA.

'We are disappointed that the interim analysis of the Phase IIb clinical trial resulted in discontinuation of the study, especially given the unmet medical need for DLBCL patients,' said Clay Siegall, chief executive of Seattle Genetics. 'In collaboration with Genentech, we will conduct a detailed analysis of data from the SeaGen MARINER trial. In addition, we are continuing four ongoing Phase Ib studies of dacetuzumab for non-Hodgkin lymphoma and multiple myeloma.'