( SEATTLE June 04 2007 /PRNewswire-Fir...)ZymoGenetics Reports Results From Atacicept Phase 1b Clinical Trial,in B-Cell Chronic Lymphocytic Leukemia,Health

SEATTLE, June 04, 2007 /PRNewswire-FirstCall/ -- ZymoGenetics, Inc. today announced that interim findings were presented from a Phase 1b clinical trial with atacicept in B-cell chronic lymphocytic leukemia (B-CLL) at the American Society of Clinical Oncology (ASCO) 2007 annual meeting. The study included intravenous administration of higher doses than had been tested in previous studies.

"We found that atacicept was well-tolerated and biologically active at all dose levels in this study, consistent with the results of our other clinical trials," said Douglas E. Williams, Ph.D., Executive Vice President and Chief Scientific Officer of ZymoGenetics. "Together with our partner Merck Serono, we will assess the results of this and our other B-cell malignancy studies, once the studies are complete, to see whether the data support moving forward in these indications."

Atacicept in B-CLL Study Design and Results

In a Phase 1b open-label, dose escalation study, 15 patients with refractory or relapsed disease were given weekly intravenous doses of atacicept ranging from 1 mg/kg to 20 mg/kg, for five weeks. Treatment with atacicept was well tolerated at all dose levels in the study. No dose limiting toxicities or serious adverse events related to study drug have been reported to date. Among the six patients given 10 mg/kg and 15 mg/kg, three (50%) showed signs of disease stabilization, using National Cancer Institute-sponsored Working Group criteria, during the treatment period. Prior to atacicept treatment, all of these patients had rapidly increasing leukocyte counts. One patient, who received 10 mg/kg, exhibited stable disease for over six months.

Biological activity of atacicept was demonstrated in these patients by reduced immunoglobulin (Ig) concentrations after treatment at all dose levels. Mean IgA, IgG and IgM concentrations decreased by 20%, 22% and 15% from baseline, respectively, af
'"/>