Coulter Pharmaceutical reports preliminary data on Bexxar as first-line therapy for non-Hodgkin's lymphoma.

PALO ALTO, Calif.--(BW HealthWire)--May 20, 1997--Coulter Pharmaceutical Inc. (NASDAQ:CLTR) today announced preliminary clinical data on its Bexxar radiolabeled monoclonal antibody which is being investigated as a first-line therapy for low-grade non-Hodgkin's lymphoma, a lethal blood-borne cancer of the immune system.

The data, which were presented at the American Society of Clinical Oncology meeting being held this week in Denver, revealed that all patients responded to the therapy, with a greater than 50 percent shrinkage of their tumors.

The preliminary data, generated from 17 patients of a planned 60-patient study, were presented by Mark S. Kaminski, M.D., associate professor of Internal Medicine at the University of Michigan Comprehensive Cancer Center and principal investigator for the clinical trial. All patients in the study were diagnosed with advanced-stage, low-grade lymphoma and were previously untreated for their disease. Of the 17 patients enrolled, 13 had high tumor burdens (greater than 500g) and 13 were symptomatic, including vital organ impairment and disfigurement.

Following Bexxar therapy, all 17 patients experienced a greater than 50 percent reduction of tumor mass. Seven of these patients experienced complete responses (remissions with no detectable cancer cells). Nine other patients were categorized as partial responses where tumor shrinkage was still occurring. At the time of the presentation, one patient had relapsed. Side effects were reversible and self-limiting, and included modest myelosuppression in all patients and 1-2 days of flu-like syndrome (fever, headache, itching and muscle and joint pain) in seven patients.

"To my knowledge, this is the first time a monoclonal antibody therapy has been used as a stand-alone therapy in newly diagnosed cancer patients," said Dr. Mark S. Kaminski. "These preliminary results are encouraging and demonstrate the promise of this therapy to be more effective and less toxic than traditional chemotherapy regimens.

"The safety profile of the radiolabeled antibody to date is quite attractive as the therapy does not appear to cause many of the side effects typically associated with chemotherapy. We look forward to completing the study and assessing the long-term benefits of this antibody therapy."

The antibody treatment is administered in a regimen which consists of two intravenous doses given about one week apart -- first an imaging dose and then a therapeutic dose. This is in contrast to conventional chemotherapy where treatment is given repeatedly over several months.

The Bexxar therapy, which is an antibody conjugated to radiolabeled iodine, attaches to a protein found only on the surface of B-cells, both non-Hodgkin's lymphoma B-cells and some normal B-cells. Through this targeted approach, the tumor cells receive a greater concentration of the therapeutic radiation from Bexxar relative to normal tissues.

Coulter also is evaluating Bexxar in a multicenter, pivotal Phase II/III clinical study in low-grade non-Hodgkin's patients who are refractory to chemotherapy. The company plans to complete enrollment in this trial by year-end and expects to file a biologics license application (BLA) with the FDA in the second half of 1998.

Michael F. Bigham, president and chief executive officer of Coulter Pharmaceutical, said, "These data on Bexxar as a first-line therapy for non-Hodgkin's lymphoma are encouraging. We are pursuing an initial indication in patients with refractory, low-grade non-Hodgkin's lymphoma who have failed previous chemotherapy regimens. We also intend to explore the use of Bexxar in all stages of low-grade NHL including newly diagnosed and relapsed patients.

"Our goal is to offer patients afflicted with this devastating disease an alternative therapy with fewer side effects and greater effectiveness."

Non-Hodgkin's lymphoma (NHL) is a form of cancer that affects the blood and lymph tissues. According to statistics from the National Cancer Institute, approximately 270,000 people are afflicted with NHL in the United States alone. Of the total, the company estimates that approximately 140,000 people have low-grade or transformed low-grade disease. NHL currently is the sixth leading cause of death among cancers in the U.S. and has the second fastest growing mortality rate. There are approximately 54,000 new cases of NHL diagnosed each year.

Coulter Pharmaceutical is engaged in the development of novel drugs and therapies for the treatment of people with cancer. The company currently is developing a family of cancer therapeutics based upon two platform technologies: conjugated antibodies and tumor-activated peptide (TAP) pro-drugs. The company's most advanced product candidate is Bexxar (previously referred to as the B-1 Therapy) for the treatment of non-Hodgkins lymphoma. The company also is developing a TAP pro-drug version of doxorubicin to potentially treat certain solid tumor cancers.

Except for the historical information contained herein, the matters discussed in this news release are forward-looking statements that involve risks and uncertainties including uncertainties related to product development, uncertainties related to the need for regulatory and other government approvals, dependence on proprietary technology, uncertainty of market acceptance of Bexxar or the company's other product candidates and other risks detailed from time to time in the company's filings with the Securities and Exchange Commission. In particular, see "Item 1. Financial Business-Risk Factors" of the company's Form 10-K for the year ended Dec. 31, 1996.

CONTACT: Coulter Pharmaceutical

Sylvia Wheeler, 415/842-7306