New Data Demonstrate ZEVALIN(R) Radioimmunotherapy May Play Greater Role in Combination with Standard of Care for Various Types of Lymphoma

Biogen Idec Inc. (Nasdaq:BIIB) announced that new data, presentedtoday at the 47th Annual Meeting of the American Society of Hematology(ASH) in Atlanta, December 10-13, demonstrate that patients maybenefit from earlier and consolidated use of ZEVALIN(R) (IbritumomabTiuxetan) radioimmunotherapy in refractory and hard-to-treat cancers,including diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma(MCL), and follicular non-Hodgkin's lymphoma (FL).

"The ZEVALIN data released at this year's ASH meeting indicate theimportance of ZEVALIN to research and the future of cancer treatment,"said Arturo Molina, M.D., senior director, Medical ResearchOncology/Hematology for Biogen Idec. "What's particularly intriguingabout these data is that they demonstrate how therapies such asZEVALIN may be integrated into the current standard of care for avariety of lymphomas. Just as researchers in HIV look to 'cocktails'of therapies to better manage patient disease, we are continuallylooking at how we can integrate radioimmunotherapy in the oncologyarena to give patients additional options and extend survival."

ZEVALIN Plus a Standard Treatment Regimen May Help Prevent Relapsein DLBCL

Paul A. Hamlin, M.D., of Memorial Sloan-Kettering Cancer Center,delivered a poster presentation discussing a Phase II study that isexploring the feasibility and effectiveness of first line use ofZEVALIN and standard rituximab plus CHOP (R-CHOP) chemotherapy inolder patients with high risk diffused large B-cell lymphoma (DLBCL),a disease that represents approximately one-third of all lymphomas andprimarily impacts people over 60 years of age.

Patients received R-CHOP chemotherapy at standard doses forinduction therapy. After hematologic recovery and R-CHOP restaging,patients were eligible for ZEVALIN, which was given 6-9 weeks postR-CHOP.

No patients receiving the full treatment regimen of ZEVALIN andR-CHOP in this study relapsed, with 21-month median follow-up. Inaddition, sequential R-CHOP followed by ZEVALIN was associated withmanageable toxicities. As part of a unique collaborative effort, TheUniversity of Texas M.D. Anderson Cancer Center has joined MemorialSloan Kettering Cancer Center in accruing additional patients for thisstudy.

"We continue to learn more about the benefits of systemicradioimmunotherapy in a variety of lymphomas and we have not yetreached the limits of this therapy's capabilities," said Paul A.Hamlin, M.D., Memorial Sloan-Kettering Cancer Center. "The results ofthis study are particularly encouraging given the growing number ofpatients with high risk DLBCL who are under-served by currenttherapies."

ZEVALIN Consolidation as Part of an Abbreviated ChemotherapyRegimen

Nicholas A. DeMonaco, M.D., of the University of Pittsburgh,delivered a poster presentation describing a Phase II study designedto evaluate the safety and efficacy of abbreviated CHOP-rituximab(CHOP-R) followed by ZEVALIN and rituximab in patients withpreviously-untreated follicular non-Hodgkin's lymphoma.

In this study, eligible patients are given CHOP-R in standarddoses. Four weeks after the last dose, patients receive the ZEVALINtherapeutic regimen, followed by four doses of rituximab one weeklater.

At the planned interim analysis after accrual of 19 patients, 8patients had completed therapy and follow-up studies. The overallresponse rate after three cycles of CHOP-R was 75% with a completeresponse in two of the eight patients (25%). After treatment withZEVALIN and rituximab, seven of eight patients achieved a completeresponse (87.5%).

ZEVALIN May Help Reduce Relapse in High Risk Mantle Cell Lymphoma

Amrita Krishnan, M.D., of the City of Hope National Cancer Center,delivered an oral presentation discussing the benefits of a newtransplant strategy involving ZEVALIN to reduce relapse in high riskmantle cell lymphoma, a disease for which there are typically nolong-term survivors. High dose chemotherapy (HDC) with autologous stemcell transplantation (ASCT) has been used for some of these patients,however, relapse rates remain high. This trial was designed toinvestigate the efficacy of combining ZEVALIN with HDC and ASCT toreduce relapse rates in patients with high-risk MCL.

Eighteen patients with MCL were enrolled in one of two ZEVALINASCT trials. The first was a phase I/II dose escalation trial ofhigh-dose ZEVALIN plus cyclophosphamide and etoposide. The secondstudy was a phase I/II trial of standard dose ZEVALIN and BEAM (BCNU,cytarabine, etoposide, melphalan).

No patients administered ZEVALIN as part of this study experiencedrelapse in the first 12 months. With a median follow up of 19 months,the estimated overall survival and disease free survival at two yearsfor patients with high-risk mantle cell lymphoma enrolled in the studyand treated with ZEVALIN is 79% and 59% respectively.

ZEVALIN May Provide an Effective Treatment Option for Relapsed andRefractory MCL

Anas Younes, M.D., of the UT M.D. Anderson Cancer Center,delivered a poster presentation discussing results from an ongoingphase II study designed to evaluate the efficacy and safety of ZEVALINfor patients with relapsed and refractory mantle cell lymphoma (MCL).

Twenty-two patients were enrolled in the study. All patients hadbeen previously treated with rituximab with or without otherchemotherapy. The median number of prior regimens was three.

Objective responses were observed in eight of 22 patients (36%),including three complete responses (23%).

"Although the duration of responses has been short, the potentialfor ZEVALIN to prolong the lives of heavily pretreated MCL patientsseems promising," said Younes. "We believe that further investigationinto the efficacy of ZEVALIN in these patients, particularly asfront-line therapy or after first relapse, is warranted."

ZEVALIN Safety Profile

Rare deaths have occurred within 24 hours of rituximab infusions.These fatalities were associated with an infusion reaction symptomcomplex that included hypoxia, pulmonary infiltrates, acuterespiratory distress syndrome, myocardial infarction, ventricularfibrillation, or cardiogenic shock. Yttrium-90 ZEVALIN administrationresults in severe and prolonged cytopenias in most patients. Patientsexperiencing severe cutaneous and mucocutaneous reactions should notreceive any further components of the ZEVALIN therapeutic regimen andshould seek prompt medical evaluation.

In safety data based upon 349 patients, the most serious adversereactions of the ZEVALIN therapeutic regimen were primarilyhematologic, with grade 4 neutropenia, thrombocytopenia, and anemiaoccurring in 30%, 10% and 3% of patients treated at the 0.4 mCi/kgdose, respectively. Infusion-related toxicities were typically grade 1or 2 and were associated with pre-administration of rituximab(RITUXAN). The risk of hematologic toxicity correlated with the degreeof bone marrow involvement prior to ZEVALIN therapy. Seven percent ofpatients were hospitalized with infection (3% of these hadneutropenia) and fatal cerebral hemorrhage (less than 1%) has occurredin a minority of patients in clinical studies. Myelodysplasia or acutemyelogenous leukemia was observed in 1% of patients (8 to 34 monthsafter treatment).

ZEVALIN should only be used by health care professionals qualifiedby training and experience in the safe use of radionuclides.

About ZEVALIN

On February 19, 2002, the ZEVALIN therapeutic regimen became thefirst radioimmunotherapy approved by the U.S. Food and DrugAdministration (FDA). Radioimmunotherapy is an innovative form ofcancer treatment that offers an option to patients with certain typesof B-cell non-Hodgkin's lymphoma who have failed to adequately respondto other cancer therapies. ZEVALIN is FDA-approved for the treatmentof patients with relapsed or refractory low grade, follicular ortransformed B cell non Hodgkin's lymphoma, including patients withrituximab (RITUXAN) refractory follicular non-Hodgkin's lymphoma.Determination of the effectiveness of ZEVALIN in a relapsed orrefractory patient population is based on overall response rates. Theeffects of ZEVALIN on survival are not known.

The ZEVALIN therapeutic regimen combines a monoclonal antibodywith a radioisotope. The monoclonal antibody in ZEVALIN recognizes andattaches to a particular cell-surface protein on B-cells called theCD20 antigen. This allows ZEVALIN to specifically target B-cells,destroying malignant NHL B-cells and also normal B-cells. The genericname for ZEVALIN is ibritumomab tiuxetan.

Today, ZEVALIN is being investigated in a variety of lymphomasubtypes including aggressive disease. ZEVALIN is also being studiedin a number of different treatment strategies including combinationswith front-line and salvage chemotherapy regimens and as part ofautologous and allogeneic stem cell transplantation in both indolentand aggressive lymphoma subtypes.

About Biogen Idec

Biogen Idec creates new standards of care in oncology, neurologyand immunology. As a global leader in the development, manufacturing,and commercialization of novel therapies, Biogen Idec transformsscientific discoveries into advances in human healthcare. For ZEVALINproduct labeling, press releases and additional information about thecompany, please visit http://www.biogenidec.com.

Biogen Idec Safe Harbor

This press release contains forward-looking statements regardingZEVALIN as a treatment for various indications. These statements arebased on the companies' current beliefs and expectation. Drugdevelopment involves a high degree of risk. Factors which could causeactual results to differ materially from the companies' currentexpectations include: the risk that unexpected concerns may arise fromadditional data or analysis, that regulatory authorities may requireadditional information, further studies, or may fail to approve thedrug, or that the company may encounter other unexpected hurdles. Formore detailed information on the risks and uncertainties associatedwith Biogen Idec's drug development and other activities, see theperiodic reports of Biogen Idec Inc. filed with the Securities andExchange Commission. Biogen Idec assumes no obligation to update anyforward-looking statements, whether as a result of new information,future events or otherwise.