Schering AG and Biogen Idec Announce Start of the ZEAL Phase III Clinical Trial With Anti-Cancer Drug Zevalin(R).

First U.S. Patient Enrolled in Trial to Assess Drug's Efficacy and Safety in Non-Hodgkin's Lymphoma Patients

BERLIN & CAMBRIDGE, Mass. -- 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.

This is an open-label, prospective, randomized, two-armed, group-sequential study evaluating the efficacy and safety of Zevalin treatment vs. observation in patients with diffuse large-B-cell lymphoma (DLBCL) - the most common type of aggressive non-Hodgkin's lymphoma (NHL) - who are in complete remission (CR) or unconfirmed complete remission (CRu) after first-line CHOP-rituximab (CHOP-R) therapy. The trial is being conducted in 46 U.S. and 57 European, Asian and Canadian centers. The duration of treatment will consist of two treatment days one week apart followed by a 12-week safety follow-up period. The study duration will be approximately four years. Entry criteria include patients older than 60 years of age with DLBCL who are in CR or CRu after six or eight cycles of first-line treatment with CHOP-R.

The primary endpoint for the trial is overall survival (OS), with disease-free survival and health-related quality of life as secondary endpoints. Once the final data from the trial is completed and analyzed, Schering AG and Biogen Idec expect to file an application seeking to expand the product's current label to include first-line therapy for patients with aggressive DLBCL.

"We have made great advances in the treatment of diffuse large B-cell lymphoma in the past decade, but a significant portion of patients still die rapidly from this aggressive cancer. We now have data from several other clinical trials suggesting that Zevalin radioimmunotherapy may provide a real advantage for these patients," said Wayne Saville, M.D., director of Medical Affairs for the Biogen Idec Oncology unit.

For more information on the ZEAL clinical trial, please visit www.clinicaltrials.gov.

Other Clinical Studies Evaluating Zevalin in the Treatment of DLBCL:

* A phase II trial evaluating Zevalin as a second-line treatment for patients with DLBCL who were not eligible for stem cell transplantation showed that Zevalin induced high response rates in DLBCL patients who have relapsed or are refractory to combination chemotherapy alone (n=76) (i.e., CHOP or CHOP-like) or chemotherapy plus rituximab (n=28). Overall response rates (ORR) were 58 percent and 19 percent in the chemotherapy and chemotherapy plus rituximab groups, respectively. The respective complete response rates for the treatment groups were 33 percent and 11 percent. Durable responses were seen in all patient groups. Around 20 percent of the patients are still in response after at least one year of follow-up according to data presented at the 2004 American Society of Hematology (ASH) meeting and at the 9th International Congress on Malignant Lymphoma in Lugano in 2005. (Morschauser et. al.)

* A phase II clinical trial evaluated the safety and efficacy of R-CHOP followed by the Zevalin therapeutic regimen in frontline treatment of elderly patients with DLBCL. Fifteen patients completed the entire treatment regimen (R-CHOP plus Zevalin) and were followed for >12 weeks, and none of the patients relapsed with a median follow-up of 21 months as presented at the 2005 ASH meeting. (Hamlin et. al.)

About Zevalin Radioimmunotherapy

In February 2002, the Zevalin therapeutic regimen became the first radioimmunotherapy approved by the U.S. Food and Drug Administration (FDA) for the treatment of relapsed or refractory low-grade follicular or transformed B-cell NHL and in January 2004, for adult patients with rituximab-relapsed or refractory CD20-positive follicular B-cell NHL in Europe. Radioimmunotherapy is an innovative form of cancer treatment that offers an option to patients with certain types of B-cell NHL who have failed to adequately respond to other cancer therapies.

The Zevalin therapeutic regimen combines a monoclonal antibody with a radioisotope. The monoclonal antibody in Zevalin recognizes and attaches to a particular cell-surface protein on B-cells called the CD20 antigen. This allows Zevalin to specifically target B-cells, delivering the isotope yttrium-90 directly to the tumor cells.

Zevalin binds to both malignant and normal B-cells. As part of the Zevalin therapeutic regimen, patients receive a dose of an unlabeled antibody (rituximab) in order to remove normal cells carrying the CD20 antigen from the peripheral blood system. With the peripheral blood cleared of CD20 targets, the radiolabeled antibodies are available to bind to the cells in the tumor cluster, minimizing potential radioactivity from being distributed through the body by circulating lymphocytes. Normal B-cells are generally replenished by CD20-negative progenitor cells within six to nine months after therapy. Yttrium-90 emits only beta radiation, so that hospitalization or patient isolation for several days or even weeks after treatment is not required with Zevalin radioimmunotherapy. Yttrium-90 Zevalin may be safely administered on an outpatient basis in the United States and in most European countries.

About NHL

Non-Hodgkin's lymphoma is a type of cancer that occurs within the lymphatic system. NHL is the fifth most common cancer after breast, prostate, lung and colon cancer. It originates from lymphocytes, a type of white blood cells, which can be divided into two main types, B lymphocytes and T lymphocytes (also called B-cells or T-cells). In adults, approximately 85 percent of NHL cases are of B-cell origin.

Non-Hodgkin's lymphomas can be divided clinically into two general categories: indolent lymphomas, mainly typified as follicular lymphomas, that tend to grow relatively slowly, and aggressive lymphomas, mainly typified as DLBCL, which grow more rapidly. DLBCL is the most common lymphoma subtype, accounting for about 50 percent of all non-Hodgkin's lymphomas among elderly patients. The aggressive type of NHL has a shorter natural history, but a significant number of these patients can be cured with combination chemotherapy regimens. However, the prognosis is poor for patients who have relapsed or who are refractory following CHOP or R-CHOP regimen. The prognosis is especially poor for those who are not candidates for stem cell transplantation.

For reasons that include the aging of the U.S. population, incidence of NHL has nearly doubled over the past 30 years. It is estimated that approximately 360,000 Americans are currently living with NHL, and about 58,000 new cases are expected in the United States this year. This incidence is currently increasing in the United States by 2-3 percent per year.

The median age at diagnosis is 55-60 years, with NHL being slightly more common in men than women. Risk factors include pre-existing infection (particularly HIV, Epstein-Barr virus and T-lymphotropic virus type 1), exposure to certain chemicals, previous organ transplant and family history of the disease.

Zevalin Safety Profile

Rare deaths have occurred within 24 hours of rituximab infusions. These fatalities were associated with an infusion reaction symptom complex that included hypoxia, pulmonary infiltrates, acute respiratory distress syndrome, myocardial infarction, ventricular fibrillation or cardiogenic shock. Yttrium-90 Zevalin administration results in severe and prolonged cytopenias in most patients. Patients experiencing severe cutaneous and mucocutaneous reactions should not receive any further components of the Zevalin therapeutic regimen and should seek prompt medical evaluation.

In safety data based upon 349 patients, the most serious adverse reactions of the Zevalin therapeutic regimen were primarily hematologic, with grade four neutropenia, thrombocytopenia, and anemia occurring in 30 percent, 10 percent and 3 percent of patients treated at the 0.4 mCi/kg dose, respectively. The risk of hematologic toxicity may be increased when the Zevalin therapeutic regimen is administered after fludarabine-containing chemotherapy. Infusion-related toxicities were typically grade one or two and were associated with pre-administration of rituximab (Rituxan). The risk of hematologic toxicity correlated with the degree of bone marrow involvement prior to Zevalin therapy. Seven percent of patients were hospitalized with infection (3 percent of these had neutropenia) and fatal cerebral hemorrhage (less than 1 percent) has occurred in a minority of patients in clinical studies. Myelodysplastic syndrome and/or acute myelogenous leukemia have been reported.

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

About Biogen Idec

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

Biogen Idec Safe Harbor

This press release contains forward-looking statements regarding Zevalin as a treatment for various indications. These statements are based on the companies' current beliefs and expectation. Drug development involves a high degree of risk. Factors which could cause actual results to differ materially from the companies' current expectations include: the risk that unexpected concerns may arise from additional data or analysis, that regulatory authorities may require additional information, further studies, or may fail to approve the drug, or that the company may encounter other unexpected hurdles. For more detailed information on the risks and uncertainties associated with Biogen Idec's drug development and other activities, see the periodic reports of Biogen Idec Inc. filed with the Securities and Exchange Commission. Biogen Idec assumes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.