CHICAGO--(BUSINESS WIRE)--Biogen Idec (NASDAQ: BIIB) announced today that data presented at the 43rd American Society of Clinical Oncology (ASCO) annual meeting showed that adding Zevalin® (Ibritumomab tiuxetan) radioimmunotherapy to a short course first-line treatment followed by rituximab weekly for four weeks doubled the rate of complete response in patients with follicular lymphoma, from 44 percent with a standard treatment regimen to 88 percent. Additionally, the response rate (complete and partial responses) for patients in the study was 100 percent based on PET scan assessment.