Updated Clinical Data in Zevalin Pivotal Trial for B-cell Non-Hodgkins Lymphoma Show Durable Remissions; Results Presented at Annual Society of Biological Therapy Meeting

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(BUSINESS WIRE) — IDEC Pharmaceuticals Corporation (Nasdaq: IDPH) announced it presented updated response duration data of Zevalin(R) (ibritumomab tiuxetan) in its Phase III randomized, controlled study of 143 patients with relapsed or refractory low grade, follicular, or transformed B-cell non-Hodgkins lymphoma (NHL) at the 17th Annual Meeting of the Society for Biological Therapy in San Diego, November 8-10, 2002.

In the pivotal study, which was previously reported, the treatment arm receiving the Zevalin therapeutic regimen showed an overall response rate (ORR) of 80 percent and a complete response (CR) rate of 34 percent, compared to the Rituxan alone control arm, which showed an overall response rate of 56 percent and a CR rate of 20 percent. The median time to progression (TTP) between the two arms was not statistically different, although there was a trend towards longer TTP in patients with follicular NHL (15.0 months in the Zevalin arm versus

  • 10.2 months in the Rituxan arm) and patients who achieved a CR (24.7 months versus 13.2 months, respectively). A complete response is achieved in a clinical trial when disease is no longer detectable.

“Among patients achieving a CR in the Zevalin arm, 32.1 percent are still in remission approximately three to four years (34 to 49 months) later,” said Christine A. White, IDEC’s Vice President, Medical Affairs. “Rituxan(R) control arm patients had fewer CRs with shorter median duration, however, 36 percent of Rituxan treated patients achieving CR also have remained in remission for approximately three to four years (36 to 51 months).”

“One of the purposes of the International Society for Biological Therapy of Cancer is to bring together scientists and clinicians to hear the latest advances in biologic therapy,” said Dr. Robert Dillman, Medical Director of Hoag Cancer Center and Society President. “The presentation of the updated Zevalin response duration data by Dr. White of IDEC is an example of what this meeting is about.”

Radioimmunotherapy

During her presentation Dr. White noted: “Zevalin is the only radioimmunotherapy (RIT) that has been compared with Rituxan in a randomized, controlled study in Rituxan-naive patients with relapsed or refractory, low grade, follicular, or transformed B-cell NHL. Both Zevalin and Rituxan can induce long-term durable responses in NHL patients.”

On February 19, 2002, IDEC received marketing approval in the U.S. for Zevalin, which is the first radioimmunotherapy approved 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, including patients with Rituximab-refractory, follicular NHL.

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. 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.

Safety

In safety data based upon 349 patients, the most serious adverse reactions of the Zevalin therapeutic regimen included severe infusion reactions and 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). Infections requiring hospitalization (7%) and fatal cerebral hemorrhage (less than 1%) have occurred in a minority of patients in clinical studies. Also seen were myeloid malignancies and dyscrasias (myelodysplastic syndrome).

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: 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. Prolonged and Severe Cytopenias: Yttrium-90 Zevalin administration results in severe and prolonged cytopenias in most patients.

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.

IDEC Pharmaceuticals Corporation is a leader in the discovery, development, and commercialization of targeted immunotherapies for the treatment of cancer and autoimmune diseases. IDEC discovered and developed the first commercially available radioimmunotherapy product (Zevalin) approved in the United States and, with co-promotion partner Genentech, Inc., the first monoclonal antibody product (Rituxan) approved in the United States, both for the treatment of cancer. IDEC is a San Diego-based, integrated biopharmaceutical company with multiple products in clinical stage development and strategic alliances involving a variety of research platforms.

For a menu of IDEC’s current news releases and quarterly reports or to retrieve a specific release, call (888) 329-2309.

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 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, 2001 and Form 10-Q for the quarter ended September 30, 2002, 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, Rituxan and Zevalin are registered U.S. trademarks of the company. The company’s headquarters are located at 3030 Callan Road, San Diego, CA 92121.

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CONTACT: IDEC Pharmaceuticals Corporation