By Matthew Willett

Amgen Inc. submitted more information to the FDA on its interleukin-1 (IL-1) receptor antagonist, Kineret (anakinra), the first such inhibitor specifically developed against rheumatoid arthritis.

Rheumatoid arthritis patients produce too much IL-1, a protein that leads to bone and cartilage erosion. Kineret is a recombinant human protein that antagonizes the receptor associated with IL-1.

Amgen, of Thousand Oaks, Calif., included data from its latest 500-patient efficacy study and a 1,300-patient safety study. Amgen filed for regulatory approval for Kineret in December 1999, based on a 419-person Phase II study that showed 42 percent of patients receiving an injection once a day in combination with methotrexate achieved a meaningful clinical response, compared to 23 percent of the patients receiving placebo. (See BioWorld Today, Nov. 16, 1999.)

Amgen¿s senior director of product development, Bob Baltera, said the additional data is a part of Amgen¿s biologics license application submission, and both trials are ongoing.

¿The first part we submitted is data on 500 patients that combines efficacy and safety information for the first six months,¿ Baltera said. ¿It¿s part of a study that has the primary endpoint of one-year bone data, and we¿re not releasing the results of this efficacy data publicly until that bone study is complete, but it¿s useful for the agency.¿

The second study, Baltera told BioWorld Today, ¿is over 1,300 patients, a broad patient subset, and it¿s all safety data. It¿s a very broad, almost an open-entry, population.¿

Baltera said the drug¿s mechanism of action is unique, in that it attacks an inflammatory cascade pathway that other drugs disregard: IL-1.

¿Recently, a number of new biologics have come to the market that specifically block cytokines involved in the pathogenesis of the disease,¿ he said. ¿A number of products block TNF-alpha [tumor necrosis factor-alpha]. Our product is different in that it doesn¿t block TNF-alpha, it blocks IL-1. What there is, is a sort of competitive binding. It¿s who gets to the receptor first. Normal people have a balance ¿ at times you want some inflammatory cascade reactions ¿ but [rheumatoid arthritis] patients have shown that the seesaw tips the inflammatory response up. We¿re supporting the body¿s ability to restore normalcy with the IL-1 mechanism.¿

Baltera said the FDA normally takes about 18 months to review BLA applications, and this time frame will come to term during the summer. Amgen expects action in the second half of this year, he said.

The company also is awaiting review of its prostate cancer therapeutic, abarelix depot, and is pursuing approval for its next generation erythropoietin product, extended-release Neupogen, or SD/01.

Amgen¿s stock (NASDAQ:AMGN) rose 39 cents Monday, to close at $59.95.

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