Some unexpected bad news out of Seattle Genetics is driving down its stock 14 percent this morning. The Bothell, WA-based developer of antibody drugs for cancer (NASDAQ: SGEN) said a mid-stage clinical trial of an experimental lymphoma drug was halted midway through enrollment after an independent panel of data monitors determined the experimental drug was unlikely to reach its goal of beating the control group.
The Seattle Genetics antibody drug, called dacetuzumab or SGN-40, was being studied in a trial of 224 patients with diffuse large B-cell lymphoma, in combination with rituximab (Rituxan) and standard chemotherapies. Patients in the control group got the same treatment, except a placebo instead of the Seattle Genetics drug. About two-thirds of the patients were enrolled in the randomized, blinded trial before it was closed. Seattle Genetics didn’t say anything in its statement today about the safety profile of its drug.
The trial failure is a setback for Seattle Genetics, which has been developing this drug since January 2007 in partnership with Genentech and now Roche. The new antibody is designed to hit a different target found on cells, called CD40, which is found on many types of malignant B cells and is supposed to be complementary to the standard rituximab antibody that hits another target called CD20. Rituximab, the pioneering antibody for cancer, generated $2.59 billion in U.S. sales last year as it has become a standard lymphoma treatment. Yet as good as it is, patients eventually see their disease spread, and relapse after getting rituximab. Seattle Genetics pointed out in its release that it has four other smaller clinical trials of its dacetuzumab treatment for non-Hodgkin’s lymphoma and multiple myeloma, a cancer of the bone marrow.
“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, CEO of Seattle Genetics, in a statement. “In collaboration with Genentech, we will conduct a detailed analysis of data from the SeaGen MARINER trial.”
Seattle Genetics shares fell $1.79, or about 14 percent, at the opening bell this morning to $11.83.