Monday, Dec 9, 1996

IDEC Pharmaceuticals and Genentech Announce Positive Final Results

Results Of Phase II Combination Trial Also Reported

Orlando -- December 9, 1996 --

IDEC Pharmaceuticals Corporation (Nasdaq: IDPH) and Genentech, Inc. (NYSE: GNE) have announced positive final results from a pivotal Phase III trial of IDEC-C2B8 as a single agent therapy for relapsed low grade or follicular non-Hodgkin's lymphoma. The trial, conducted in a total of 166 patients, confirmed the antibody's overall response rate and safety profile as seen in an earlier Phase II study. The companies additionally reported final results from a Phase II combination trial of IDEC- C2B8 and CHOP chemotherapy. Results of both trials are being presented today by clinical investigators Myron Czuczman, M.D. of the Roswell Park Cancer Institute and Peter McLaughlin, M.D. of the M.D. Anderson Cancer Center at the annual meeting of the American Society of Hematology (ASH) held in this city.

In Phase III open label, single arm testing of IDEC-C2B8 as a single agent therapeutic, each of the patients participating at over 30 trial centers received four infusions of the antibody on an outpatient basis during a 22-day period. Of 151 evaluable patients, 76 responded to treatment with IDEC-C2B8, for an overall response rate of 50%. Nine of these responses were complete responses (6%) and 67 were partial responses (44%). At over nine months' median followup, the median time to disease progression for responders following treatment with IDEC-C2B8 has not yet been reached. Of the responding patients, 70% remain in remission. Patients continue to be followed.

The adverse events associated with IDEC-C2B8 were mostly infusion-related. These side effects consist primarily of mild to moderate flu-like symptoms (e.g., fevers, chills) and occur with greatest frequency upon initial administration. The symptoms are limited in duration to the period of infusion, may be ameliorated with oral acetaminophen and diphenhydramine and decrease significantly in frequency with subsequent infusions.

As a matter of scientific interest, patients were also monitored for the presence of a tumor marker gene known in medical research as Bcl-2. Results presented at ASH revealed that the tumor marker gene reverted to negative in the peripheral blood of over 70% of the patients who were positive at baseline, and in the bone marrow of over 50% of patients who were positive at baseline. Researchers have previously reported clearance of this marker from bone marrow with marrow transplantation regimens incorporating 'ex vivo' marrow purging and only rarely with chemotherapy regimens. However, the clinical significance of Bcl-2 conversion has not yet been determined.

"IDEC-C2B8 has completed all Phase III clinical testing in support of regulatory filing and we are very gratified by the results we have seen for this agent to date," said Antonio J. Grillo-Lopez, M.D., IDEC's senior vice president of medical and regulatory affairs. "We have confirmed IDEC-C2B8's potential as an effective, alternative therapy with limited toxicity for patients with B-cell lymphoma. Based on these results, we expect to file a Biological License Application for IDEC-C2B8 as a single agent therapy for relapsed patients with low grade or follicular non-Hodgkin's lymphoma in the first half of 1997."

IDEC and Genentech are also investigating the use of IDEC-C2B8 in combination with other therapies for lymphoma and reported positive results in a Phase II open label, single arm trial combining IDEC-C2B8 with CHOP chemotherapy (a standard regimen of cyclophosphamide, doxorubicin, vincristine and prednisone). In this trial, patients with low grade or follicular lymphoma received six doses of IDEC-C2B8 over 21 weeks. Within this same time period, they also received six cycles of CHOP chemotherapy. Of the 35 patients completing all treatments, 35 responded to treatment, for an overall response rate of 100%. Twenty-two patients (63%) achieved a complete response and 13 (3%) achieved a partial response. Patients tolerated the combination of IDEC-C2B8 and CHOP well; adverse events did not exceed those routinely observed with CHOP alone or those associated with IDEC-C2B8 alone, indicating compatibility of the two therapies.

"Based on the limited toxicity and patient response rates observed to date for IDEC-C2B8 as a single agent therapeutic, Genentech and IDEC are committed to exploring further uses for IDEC-C2B8, both as a frontline therapy, and in combination with other anti-cancer treatments," said Sue Hellmann, M.D., Genentech vice president, medical affairs. "Genentech is currently conducting a study of IDEC-C2B8 in combination with chemotherapy in patients with intermediate grade disease and additional combination therapy trials are planned."

B-cell lymphomas are malignancies of the body's antibody-producing immune system cells. Non-Hodgkin's lymphomas currently afflict roughly 225,000 Americans, with over 50,000 new diagnoses expected this year. Low grade and follicular lymphomas comprise about 65% of the total lymphoma. prevalence in the United States.

IDEC-C2B8 is a monoclonal antibody that is therapeutically active on its own and does not require the attachment of radioisotopes or toxins to elicit its anti-tumor effect. The antibody targets a protein (the CD20 antigen) that is expressed on the surface of mature B cells and on B-cell tumors, but not on B-cell precursors or other body tissues. IDEC-C2B8 works by binding to its target antigen and recruiting the patient's natural defenses to attack and kill both malignant and normal mature B cells. In trials to date, the normal B cells regenerate from stem cells and return to normal levels within months following treatment with IDEC-C2B8. In addition, clinical results to date have shown that IDEC-C2B8 does not exhibit any significant toxicities that overlap with those produced by chemotherapy or high dose radiation. Thus, treatment with IDEC-C2B8 has not precluded patients from receiving subsequent chemotherapeutic treatments. In addition, IDEC-C2B8 is administered over 22 days, versus the four- to eight-month course required for most conventional chemotherapies.

IDEC and Genentech are developing IDEC-C2B8 in collaboration with F.Hoffmann-La Roche, Ltd. of Switzerland and Zenyaku Kogyo Co. Ltd. of Japan. Genentech, Inc. is a leading international biotechnology company that discovers, develops, manufactures and markets human pharmaceuticals for significant unmet medical needs. The company has headquarters in South San Francisco, California and is traded on the New York and Pacific Stock Exchanges under the symbol GNE.

IDEC Pharmaceuticals focuses on developing targeted immunotherapies for the treatment of cancer and autoimmune diseases. IDEC's products are primarily designed to act through immune mechanisms and offer greater specificity of action, longer therapeutic effect and lower toxicity than is typical of existing therapies. All of IDEC's products are designed for administration in outpatient settings, providing the opportunity to reduce overall treatment costs.

IDEC Pharmaceuticals' press releases and are available at no charge through PR Newswire's "Company News On Call" fax service. For a menu of IDEC's current press releases and quarterly reports or to retrieve a specific release, call (800) 758-5804, ext. 432581 or internet http://www.prnewswire.com.

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 the company's expectations. In addition to the matters described in this press release, timelines for clinical ongoing activity are subject to change, results of pending or future clinical trials cannot be accurately predicted and decisions by the FDA and other regulatory agencies, as well as the risk factors listed from time to time in the company's SEC filings, including but not limited to its Annual Reports on Form 10-K for the year ended December 31, 1995, and form S-3 filed May 3, 1996, may affect the actual results achieved by the company.

IDEC Pharmaceuticals is a registered U.S. trademark of the company. The company headquarters is located at 11011 Torreyana. Road, San Diego, CA 92121.

CONTACT: Connie Matsui of IDPH, 619-550-8656; or Laura Leber of GNE, 415-225-5759.

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