Seragen Inc.'s interleukin-2 (IL-2) fusion toxin reduced thesymptoms of patients with severe rheumatoid arthritis,according to findings presented today in Seattle at theAmerican Society for Clinical Investigation.

Seragen's drug uses diphtheria toxin stripped of its naturaltargeting mechanism, which directs the toxin to all cells. Thecompany replaces the targeting mechanism with amino acidsequences of IL-2 that direct the toxin to white blood cells withIL-2 receptors, such as lymphocytes.

Seragen said that the fusion toxin works by destroying thelymphocytes, which are activated during the onset ofrheumatoid arthritis.

The findings are based on an uncontrolled pilot study of 13patients, 12 of whom showed improvement as measured by thenumber of swollen and tender joints, duration of morningstiffness and grip strength. The study was conducted bydoctors K. Lea Sewell and David E. Trentham of Beth IsraelHospital in Boston.

Seragen, a privately held company based in Hopkinton, Mass.,will apply to the Food and Drug Administration to conduct aPhase I/II study of the drug. There are 700,000 patients withsevere rheumatoid arthritis in the United States, said RichardSvrluga, Seragen's president and chief executive officer.

Seragen is also conducting Phase II trials of the IL-2 fusiontoxin in patients with leukemias and lymphomas. In January,the company began a pilot study in Paris of the drug inpatients with type I insulin-dependent onset diabetes. -- KarenBernstein

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