Zevalin Therapeutic Regimen Receives FDA Marketing Approval; First Radioimmunotherapy Approved by FDA

(BW HealthWire) — IDEC Pharmaceuticals Corporation (Nasdaq: IDPH) today announced that Zevalin(TM) (Ibritumomab Tiuxetan) has been approved for marketing by the U.S. Food and Drug Administration (FDA). Zevalin, as part of the Zevalin therapeutic regimen, is indicated for the treatment of relapsed or refractory low grade, follicular, or transformed B-cell non-Hodgkin’s lymphoma (NHL) including patients with Rituxan(R) (Rituximab) refractory follicular NHL. The Zevalin therapeutic regimen consists of Rituxan preceding Indium-111 Zevalin followed seven to nine days later by a second infusion of Rituxan prior to Yttrium-90 Zevalin. This is the first radioimmunotherapy to receive FDA approval. It is estimated that commercial shipments of Zevalin will begin within approximately 30 to 60 days.

Non-Hodgkin’s lymphoma is the fifth most common type of cancer diagnosed in the United States. For reasons that include the aging of the U.S. population, incidence of NHL has increased over the past 20 years. It is estimated that approximately 300,000 people are currently living with NHL in the U.S.

A monoclonal antibody linked to the radioisotope Yttrium-90, Zevalin targets the CD20 antigen on the surface of mature B cells and B-cell tumors, inducing cellular damage in the target and neighboring cells.

Boxed Warning Summary: Zevalin should only be used by health care professionals qualified by training and experience in the safe use of radionuclides. Fatal Infusion Reactions: 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. Prolonged and Severe Cytopenias: Yttrium-90 Zevalin administration results in severe and prolonged cytopenias in most patients.

Efficacy and Safety Data Summary

Zevalin received two separate approvals, a full approval and an accelerated approval, based on two major efficacy studies in the U.S. Determination of the effectiveness of the Zevalin therapeutic regimen in a relapsed or refractory patient population was based on overall response rates (ORR). The effects of the Zevalin therapeutic regimen on survival are not known.

The first efficacy study, on which the full approval is based, was conducted in 54 patients with relapsed follicular lymphoma who no longer adequately responded to Rituxan, 74 percent showed an ORR to treatment with Zevalin, with 15 percent of patients achieving a complete remission (CR) to therapy, according to the International Workshop Response Criteria (IWRC).

The second study, a Phase III randomized, controlled trial, which supports accelerated approval, was conducted in 143 patients with relapsed or refractory, low grade or follicular NHL or transformed B-cell NHL. The 73 patients who received the Zevalin therapeutic regimen showed an ORR of 80 percent, compared to 56 percent in 70 patients who received Rituxan alone, according to the IWRC. Thirty percent (30%) of Zevalin patients achieved a complete remission (CR) and four percent (4%) achieved an unconfirmed complete remission (CRu) to therapy, compared to sixteen percent (16%) of Rituxan patients who achieved a complete remission and four percent (4%) who achieved an unconfirmed complete remission, according to the IWRC.

In safety data based upon 349 patients, the most serious adverse reactions of the Zevalin therapeutic regimen included severe infusion reactions (hypotension, angioedema, hypoxia or bronchospasm) and severe and prolonged cytopenias including thrombocytopenia (61% of patients with platelet counts less than 50,000 cells/mm3) and neutropenia (57% of patients with absolute neutrophil counts less than 1,000 cells/mm3) in patients with a greater than or equal to 150,000 platelets/mm3 prior to treatment. Severe infections (predominately bacterial in origin) and hemorrhage, including fatal cerebral hemorrhage, have occurred in a minority of patients in clinical studies. Also seen were myeloid malignancies and dyscrasias (myelodysplastic syndrome). The most common toxicities reported were neutropenia, thrombocytopenia, anemia, gastrointestinal symptoms (nausea, vomiting, abdominal pain, and diarrhea), increased cough, dyspnea, dizziness, arthralgia, anorexia and ecchymosis. Hematologic toxicity was often severe and prolonged, whereas most non-hematologic toxicity was mild in severity.

“This day is the fulfillment of more than a decade of hard work by hundreds of IDEC employees and clinical investigators,” said William H. Rastetter, chairman and chief executive officer of IDEC Pharmaceuticals. “Like Rituxan four years ago, Zevalin’s approval today marks another important milestone in the treatment of cancer and in the 15-year history of IDEC.”

“Zevalin represents a major advance in the treatment of certain non-Hodgkin’s lymphomas, especially among patients who have become refractory to other treatment options,” said Thomas E. Witzig, M.D., a hematologist at the Mayo Clinic, Rochester, MN, and a key investigator in the trials. “Zevalin is a significant step forward in managing patients with adequate bone marrow reserves who have failed standard chemotherapy, Rituximab therapy, or a combination of chemotherapy and Rituxan. And, unlike standard chemotherapy, which is given over as many as four to six months, Zevalin can be administered in an outpatient setting over eight days with approximately 12 weeks of follow-up.”

Radioimmunotherapy is a promising new area of cancer treatment that combines the targeting power of monoclonal antibodies with the cell-damaging ability of localized radiation. Radioimmunotherapies like Zevalin are made by linking monoclonal antibodies — engineered in a laboratory to recognize and attach to substances on the surface of certain cells — to radioactive isotopes. When infused into a patient, these radiation-carrying antibodies circulate in the body until they locate and bind to the surface of specific cells, and then deliver their cytotoxic radiation directly to malignant cells. Zevalin binds to malignant and normal B cells. Normal B cells generally are replenished by CD20-negative progenitor cells within six to nine months following therapy.

IDEC’s partner, Schering A.G., Berlin, Germany (FSE: SCH) (NYSE: SHR), which has marketing rights to Zevalin — outside the United States, had its Marketing Authorization Application (MAA) for Zevalin accepted for review by the European Medicines Evaluation Agency (EMEA) in January 2001.

IDEC Pharmaceuticals focuses on the commercialization and development of targeted therapies for the treatment of cancer and autoimmune diseases. IDEC’s antibody products act chiefly through immune system mechanisms, exerting their effect by binding to specific, readily targeted immune cells in the patient’s blood or lymphatic system.

For a menu of IDEC’s current news releases and quarterly reports or to retrieve a specific release, call (888) 329-2309. On the Internet check the News Center at IDEC’s website: http://idecpharm.cdmail.biz. Full prescribing information for Zevalin may be obtained online at idecpharm.cdmail.biz or by calling 1-877-878-4332. Full prescribing information for Rituxan is available online at www.rituxan.com or by calling 1-877-878-4332. The statements made in this press release contain certain forward-looking statements that involve a number of risks and uncertainties. Actual events or results may differ from IDEC’s expectations. For example, the timing, success and cost of preclinical research and clinical studies, the timing, acceptability and review periods for regulatory filings, the timing of and ability to obtain regulatory approval of products, the timing of product launches, the achievement of future product sales, the level of manufacturing performance and the risk factors listed from time to time in IDEC’s SEC filings including but not limited to its Annual Report on Form 10-K for the year ended December 31, 2000 and Form 10-Q for the quarter ended September 30, 2001, may affect the actual results achieved by IDEC. These forward-looking statements represent the company’s judgment as of the date of this release. The company disclaims, however, any intent or obligation to update these forward-looking statements.

IDEC Pharmaceuticals and Rituxan are registered U.S. trademarks of the company. Zevalin is a trademark of the company. The company’s headquarters are located at 3030 Callan Road, San Diego, CA 92121.CONTACT: IDEC Pharmaceuticals Corporation, San Diego Connie Matsui, 858/431-8656 Senior Vice President, Planning & Resource Development

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