Corixa and GlaxoSmithKline Announce Studies Presented at ASH Explore Activity of the BEXXAR Therapeutic Regimen in Difficult-to-Treat Lymphomas.

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SAN DIEGO--(BUSINESS WIRE)--Dec. 8, 2003

New Analysis Confirms Most Complete Remissions in Follicular 

non-Hodgkin's Lymphoma Persist for Years Following Single Treatment

with BEXXAR

Corixa (Nasdaq:CRXA) and GlaxoSmithKline (NYSE:GSK) today announced according to several studies presented at the 45th annual meeting of the American Society of Hematology (ASH), BEXXAR(R) (Tositumomab and Iodine I 131 Tositumomab) is active in a variety of patients with difficult-to-treat lymphomas, including patients with heavily pre-treated follicular non-Hodgkin's lymphoma who have had multiple relapses, patients who initially responded to but subsequently relapsed following the BEXXAR(R) therapeutic regimen, and patients with previously untreated mantle cell lymphoma who received BEXXAR as a component of sequential therapy.

The BEXXAR therapeutic regimen, which is administered in four visits over one to two weeks, is approved by the U.S. Food and Drug Administration (FDA) for use in a single course for the treatment of patients with CD20 positive, follicular, non-Hodgkin's lymphoma, with and without transformation, whose disease is refractory to the antibody treatment Rituximab and has relapsed following chemotherapy. BEXXAR is not approved for front-line use as a single agent or in combination with chemotherapy for non-Hodgkin's lymphoma or mantle cell lymphoma. BEXXAR is also not indicated for re-treatment of non-Hodgkin's lymphoma.

New Analysis of Durable Complete Responses (ASH Abstract #89)

Researchers presented a new analysis of the data on independently confirmed long-term durable responses, defined as responses with a time to progression of 12 or more months, from the five clinical trials that supported regulatory approval of the BEXXAR therapeutic regimen. Of 230 patients with relapsed or refractory follicular non-Hodgkin's lymphoma who were treated with BEXXAR and who were evaluable for response, 55 (24 percent) met the definition of a durable complete response (complete resolution of radiological abnormalities and disappearance of signs and symptoms related to the disease). Investigators reported that 75 percent of these patients (41/55) still showed no sign of disease after a median follow-up of nearly 5 years. Independently assessed durable complete responses were noted with similar frequency in patients who relapsed after or who were refractory to Rituximab therapy and in patients who had not received Rituximab prior to the BEXXAR therapeutic regimen.

"These data confirm that 20 to 25 percent of patients with follicular non-Hodgkin's lymphoma treated with BEXXAR achieved a complete response lasting a minimum of 12 months, the majority remained in complete response with a median follow-up of nearly five years," said Morton Coleman, MD, director, Center for Lymphoma and Myeloma, Weill Medical College of Cornell University and the New York Presbyterian Hospital, who presented the analysis. "For these patients, who have experienced multiple relapses and endured several courses of re-treatment, getting five or more disease-free and treatment-free years from a single, short course of therapy is very encouraging."

Re-treatment with BEXXAR (ASH Abstract #1478)

Investigators also reported findings of a Phase II, single-arm, multi-center study that examined re-treatment with BEXXAR in 32 patients who relapsed after an initial response of at least 3 months to the BEXXAR therapeutic regimen. With a median follow-up of more than 2 years, responses were reported in 18 patients (56 percent), with a median duration of 10.7 months (range, 10.0 months - not reached). Seven patients (22 percent) experienced a complete response and the median duration of complete response was not reached. Median progression-free survival was nearly 12 months (11.8 months; range, 6.2 months to 17.0 months). Response and duration of response following re-treatment were independent of the degree of prior response to BEXXAR.

Grade 3/4 neutropenia (decrease in white cell count) and thrombocytopenia (decrease in platelet count) were reported in 44 percent and 38 percent of patients respectively. Thirty-eight percent of patients had one serious adverse event, the most common of which were myelodysplastic syndrome (9 percent), fever (6 percent), postural hypotension (6 percent) and dyspnea (6 percent). Sixteen patients experienced a total of 24 infections (1 patient experienced a serious infection and 1 patient was hospitalized for neutropenic fever). The incidences of hypothyroidism and conversion to HAMA (human anti-murine antibody) positivity were similar to those reported in other clinical studies.

"Re-treatment with the BEXXAR therapeutic regimen had substantial anti-tumor activity in patients who had a prior response to this therapy," concluded Mark. S. Kaminski, MD, professor of internal medicine and co-director of the Leukemia/Lymphoma/Bone Marrow Transplant Program of the University of Michigan Cancer Center.

BEXXAR in Sequential Therapy for Mantle Cell Lymphoma (ASH Abstract #1477)

A third study analyzed the BEXXAR therapeutic regimen in sequential treatment with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) chemotherapy for previously untreated mantle cell lymphoma. Mantle cell lymphoma is an uncommon and aggressive form of non-Hodgkin's lymphoma that is often first diagnosed in an advanced stage with multiple lymph nodes, organ, and bone marrow involvement. This was the first report of a regimen containing a radioimmunotherapy followed by chemotherapy in mantle cell lymphoma.

Researchers reported data on 12 patients who received the BEXXAR therapeutic regimen; 10 of the 12 patients completed subsequent CHOP chemotherapy. CHOP was given in six cycles, at 3-week intervals, beginning 13 to 16 weeks after the BEXXAR therapeutic regimen. The overall response rate to BEXXAR was 83 percent (10/12), with a complete response rate of 50 percent (6/12). The overall response rate for the 10 patients who completed subsequent CHOP chemotherapy was 90 percent and all of these were complete responses. There were three relapses at 6, 9, and 12 months post-treatment. The median duration of response had not been reached, though follow-up remains short (median, 11+ months; range, 6+ months to 23+ months).

There were five episodes of febrile neutropenia during the CHOP chemotherapy and one episode of pericarditis of uncertain etiology following BEXXAR. One patient required surgery for complications from a lymphoma of the colon. Non-hematological side effects were mostly mild to moderate.

"Based on this small study, it appears that sequential therapy with BEXXAR followed by chemotherapy is feasible and has produced a 90 percent complete response rate in those patients who completed all therapy in a difficult-to-treat lymphoma," said Andrew Zelenetz, MD, chief, Lymphoma Service, Department of Medicine, Memorial Sloan- Kettering Cancer Center. "We will continue to follow these patients to determine if this new regimen can represent an advance in therapy for mantle cell lymphoma."

About the BEXXAR Therapeutic Regimen

BEXXAR is a dual-action therapy that pairs the tumor-targeting ability of an antineoplastic (cancer killing) monoclonal antibody (Tositumomab) and the therapeutic potential of radiation (Iodine-131) with patient-specific dosing. Combined, these agents form a radiolabeled monoclonal antibody (Iodine I 131 Tositumomab) that is able to bind to the target antigen CD20 found on non-Hodgkin's lymphoma cells, thereby initiating an immune response against the cancer and delivering a dose of radiation directly to tumor cells. BEXXAR is the only non-Hodgkin's lymphoma therapy that is specifically dosed based on an individual's drug clearance rate, allowing the delivery of a pre-determined amount of radiation to each patient.

The BEXXAR therapeutic regimen, which has been studied for over 10 years, has demonstrated independently confirmed durable responses (responses with a time to progression of at least 12 months) in heavily pre-treated patients with follicular non-Hodgkin's lymphoma. In a clinical trial in patients who had a median of 4 prior chemotherapies and who had Rituximab-refractory disease, 63 percent responded to BEXXAR. Half of these patients had a response that lasted 25 months or longer. Determination of clinical benefit of the BEXXAR therapeutic regimen was based on evidence of durable responses without evidence of an effect on survival.

The BEXXAR therapeutic regimen may not be for everyone. Patients who are pregnant should not be treated with BEXXAR. BEXXAR contains a radioactive component and patients will receive instructions on how to limit exposure to others following treatment. BEXXAR has been associated with significant, generally reversible, lowering of blood cell counts, which may result in infections or bleeding in some patients. Patients may experience weakness, fever, nausea, increased cough, infection, pain, chills, rash or headache. Allergic reactions can occur in some patients receiving BEXXAR. Patients may also experience hypothyroidism. BEXXAR may increase the long-term risk of other blood cancers. After being treated with BEXXAR, it is unusual for patients to suffer hair loss or to develop severe nausea and/or vomiting or mucositis (inflammation of mucous membranes).

About Non-Hodgkin's Lymphoma

Non-Hodgkin's lymphoma is a form of cancer that affects the blood, bone marrow and lymphatic tissues. Non-Hodgkin's lymphoma currently is the sixth-leading cause of cancer-related deaths in the United States, is expected to claim the lives of 23,400 Americans this year, and has the second-fastest-growing mortality rate. According to statistics from the National Cancer Institute (NCI), approximately 300,000 people are afflicted with non-Hodgkin's lymphoma in the United States alone. Of that total, 25 to 40 percent have follicular non-Hodgkin's lymphoma, making it the second most common type. Transformed non-Hodgkin's lymphoma is an aggressive and difficult to treat form of follicular non-Hodgkin's lymphoma with a particularly poor prognosis.

About Corixa

Corixa is a developer of immunotherapeutics with a commitment to treating and preventing cancer and infectious diseases by understanding and directing the immune system. On June 30, 2003, Corixa announced that the FDA approved BEXXAR for the treatment of patients with CD20 positive, follicular, NHL, with and without transformation, whose disease is refractory to Rituximab and has relapsed following chemotherapy.

Corixa is focused on immunotherapeutic products and has a broad technology platform enabling both fully integrated vaccine design and the use of its separate, proprietary product components on a standalone basis. In addition to BEXXAR, Corixa currently has multiple programs in clinical development, including several product candidates that have advanced to and through late stage clinical trials. The company partners with numerous developers and marketers of pharmaceuticals, targeting products that are Powered by Corixa(TM) technology with the goal of making its potential products available to patients around the world. Corixa was founded in 1994 and is headquartered in Seattle, with additional operations in Hamilton, Mont., and South San Francisco. For more information, please visit Corixa's Web site at http://www.corixa.com.

About GlaxoSmithKline

GlaxoSmithKline (NYSE:GSK) is one of the world's leading research-based pharmaceutical and healthcare companies. GlaxoSmithKline is committed to improving the quality of human life by enabling cancer patients to do more, feel better and live longer. For more information, visit www.gsk.com.

Corixa Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding the prospects for treatment with our product, BEXXAR. Forward-looking statements are based on the opinions and estimates of management at the time the statements are made. They are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Factors that could affect Corixa's actual results include, but are not limited to, the "Factors Affecting Our Operating Results, Our Business and Our Stock Price," described in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2003, copies of which are available from our investor relations department. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release.

GlaxoSmithKline Forward-Looking Statements

Under the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, the Company cautions investors that any forward-looking statements or projections made by the Company, including those made in this Announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Factors that may affect the Group's operations are described under Risk Factors in the Operating and Financial Review and Prospects in the Company's Annual Report on Form 20-F for 2002, filed with the U.S. Securities and Exchange Commission.