Xoma Corp. on Tuesday was issued a composition of matter andmethods of use patent for reagents that link monoclonalantibodies and cell-killing toxins.

U.S. Patent No. 5,093,475 covers Substituted 2-Iminothiolanes(X2IT) reagents that are used in the Berkeley, Calif., company'sfirst immunoconjugate product, CD5 Plus. The patent alsocovers other proteins that could be linked to MAbs using thisfamily of linkers, said Patrick Scannon, president.

Scannon said he knew of no other companies using the linkersto develop immunoconjugates.

CD5 Plus, which combines a MAb and the plant toxin ricin, isawaiting FDA marketing approval to treat patients with graft-vs.-host disease. GvHD is an immune system disease that occursfollowing bone marrow transplants.

Xoma shares (NASDAQ:XOMA) rose 75 cents on Tuesday to$23.25.

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