BERLIN & CAMBRIDGE, Mass.--(BUSINESS WIRE)--Schering AG, Germany (FSE:SCH) (NYSE:SHR) and Biogen Idec Inc. (NASDAQ:BIIB) today announced the start of Zevalin (Ibritumomab Tiuxetan) in Aggressive Lymphoma (ZEAL), a Phase III, international multi-center clinical trial. Approximately 400 patients will be enrolled in the trial.