By Jennifer Van Brunt
Senior Editor

Idec Pharmaceutical Corp. on Tuesday announced that it has received clearance from theFDA to begin Phase I human clinical trials of its primatized anti-CD4 antibody fortreating rheumatoid arthritis. The approval triggers a major milestone in Idec'scollaborative research and licensing agreement with SmithKline Beecham and will result ina significant cash infusion for the San Diego company.

According to the agreement signed in October 1992, pharmaceutical giant SmithKlineBeecham's (SKB) venture capital subsidiary, S.R. One Ltd., will purchase on the openmarket $1.2 million worth of Idec common stock (NASDAQ:IDPH) as well as 200,000 warrantsat $3 each that may be exercised and converted to newly issued Idec common stock for $12 ashare on Tuesday, up $1.

The original agreement stipulated that S.R. One Ltd. was to purchase $2.4 million worthof Idec's common stock on the open market and 400,000 exercisable warrants at $3 each --half of each before April 15. Idec's receipt of clearance from FDA triggered the purchaseof the other half.

SKB (NYSE:SBE) is also making a cash milestone payment of $2 million to Idec based onits receipt of FDA clearance.

The collaboration for developing and commercializing primatized anti-CD4 antibodies forautoimmune diseases was expanded in February and has the potential to reach more than $50million in milestone payments to Idec, as well as R&D funding for certain projects.

To date, Idec has received $11.4 million in milestone payments from SKB, explainedRichard Krawiec, Idec's director of investor relations and corporate communications. Thecompany will credit the newest infusions -- the $600,000 from the warrants purchase plusthe $2 million cash -- to its books for the third quarter, Kraweic told BioWorld.

Idec's primatized antibodies consist of a human constant region (which performs theantibody molecule's housekeeping functions) and a macaque monkey's variable region (whichrecognizes and binds to the CD4 receptors on helper T cells). Because such primatizedantibodies are structurally similar to human antibodies, Idec anticipates that they willnot be rejected by the human immune system under repeat administration as are mouse ormouse/human antibody constructs (known as a HAMA or human anti-mouse antibody response).

This is important when considering a disease such as rheumatoid arthritis, whichrequires long-term treatment. “Our objective is to use primatized antibodies for thelong-term management of a variety of chronic, as well as acute, conditions,“explained Antonio Grillo-Lopez, Idec's vice president of medical and regulatory affairs

“In the case of rheumatoid arthritis, we believe the primatized anti-CD4 antibodywill suppress abnormal immune activity that is characteristic of the disease and thuspotentially prevent the inflammatory changes in the patient's joints that can lead tocrippling deformities,“ Grillo-Lopez said.

Idec is responsible for initial supplies of clinical-grade antibody and early humanclinical trials, after which SKB will take the product through advanced large-scale trialsand the regulatory approval process.