Seragen Inc. announced Thursday that it has filed aninvestigational new drug (IND) application for a pilot study ofits interleukin-2 (IL-2) receptor-targeted fusion toxin,DAB389IL-2, for treating patients with moderate to severepsoriasis.

Seragen of Hopkinton, Mass., becomes the latest entrant intothe psoriasis clinical trials arena. But unlike the products thathave preceded it into human subjects, all of which have beentopical formulations (and three of which have proved onlymarginally effective; see BioWorld, July 22), Seragen'scompound is an intravenous formulation.

Moreover, Seragen's drug targets activated lymphocyteswhereas the others have targeted various factors involved inproliferative processes, including platelet activating factor,thymidylate synthase, protein kinase C and purine nucleosidephosphorylase.

Seragen (NASDAQ:SRGN) chose to focus on activatedlymphocytes because they are believed to be a criticalcomponent of disease activity in psoriasis, according to JeanNichols, Seragen's senior vice president. "Our IL-2 fusion toxinspecifically targets the high-affinity IL-2 receptor known to beexpressed by these activated lymphocytes," Nichols said.

The Phase I/II clinical trial will involve 10 patients, with morethan 10 percent of their body surface involved in the plaque-type lesions characteristic of this proliferative skin disorder.The trial will consist of two courses of IL-2 fusion toxinadministered intravenously for five consecutive days, followedby three weeks of observation for each course.

Patient response will be measured by three diseaseparameters, redness, scaling and thickness of skin; the percentof body surface affected by psoriatic plaques; andhistopathology of the lesions; explained Helen Maslocka,Seragen's director of corporate communications.

She added that the company has already been generatingsafety data on DAB389IL-2 from its clinical trials onlymphoma, severe rheumatoid arthritis and type I diabetes.

-- Jennifer Van Brunt Senior Editor

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