Idec Pharmaceuticals Corp. on Thursday announced a newroute to immune treatment of autoimmune disease, usingantibodies derived from macaque monkeys.

The new class of recombinant antibodies will not be subject tothe same limitations as the mouse antibodies that have beenthe focus of therapeutic efforts, the company predicted, andmay expand the number of conditions treatable by antibodytherapies.

The "primatized" antibodies were disclosed at the SecondInternational Conference on Human Antibodies andHybridomas in Cambridge, England. Idec (NASDAQ:IDPH) hasfiled for patent protection and expects to have an anti-CD4primatized product in clinical trials for several autoimmunediseases by 1993.

The stock gained 50 cents to $11.50 on Thursday.

Researchers at the La Jolla, Calif.-based company have beensearching for a means to avoid the human-anti-mouse (HAMA)immune response to mouse-derived antibodies that limits theiruse. Under certain circumstances, the HAMA reaction poses noproblem, or its immune stimulation may even be desirable, asin the case of therapeutic vaccines. But if repeated treatmentsare required, HAMA will preclude use of an antibody-basedtherapy.

Chimeric or mouse-human antibodies do not eliminate theHAMA problem.

Idec sought to avoid the reaction by using the macaque, whichis evolutionarily so close to humans that its antibodies closelyresemble human antibodies. Yet the macaque is distant enoughfor its antibodies to act against human proteins. Chimpanzeeswould probably be too closely related to humans for theirantibodies to work, said Nabil Hanna, vice president forresearch.

Clifford Orent, chief operating officer, said the idea is to achieveimmune recognition without inducing rejection of thetherapeutic. Testing in humans will be needed to prove that theprimatized antibodies will not cause HAMA (in this case,human-anti-macaque antibodies), Orent said.

Anti-CD4 antibodies made by macaques and tailored in the labwith human components should be able to bring down thepopulation of overactive helper T cells causing autoimmunedisease without "bringing it down too far," Orent said.

Autoimmune problems to be targeted by the company includerheumatoid arthritis, psoriasis, inflammatory bowel diseaseand multiple sclerosis, as well as the rejection of transplantedorgans.

Idec's patent application includes all Old World monkeyspecies, which have the correct evolutionary distance fromhumans, Hanna told BioWorld.

-- Roberta Friedman, Ph.D. Special to BioWorld

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