Immunex Corp. said at the 20th annual World Congress of Dermatology Meeting in Paris that it began a second Phase III trial of Enbrel in psoriasis as the company seeks its fifth approval for the drug.

"We've initiated two large trials [at this point] that would be part of our pivotal package," said Daniel Burge, vice president of clinical development at Immunex, adding that each trial is expected to enroll about 600 patients. The trial is designed to have two dosing arms, compare Enbrel to placebo, and has the "standard endpoints for these types of trials," Burge said, suggesting the company will look for patients to achieve a set percentage improvement on the Psoriasis Area and Severity Index.

At the meeting, Immunex also presented previous data from a Phase II study on psoriasis patients treated with Enbrel (etanercept). The study looked at 112 patients and produced favorable results. (See BioWorld Today, Feb. 25, 2002.)

With the two pivotal trials under way in collaboration with Wyeth, of Madison, N.J. - the first Phase III study "on schedule," Burge said - Immunex is now "aiming for approval [in psoriasis] in 2004."

Enbrel acts by binding tumor necrosis factor, a protein involved in the inflammatory process. By binding to TNF, Enbrel is designed to render it inactive and thus reduce inflammatory activity. The product was first approved in November 1998 to treat moderately to severely active rheumatoid arthritis in patients who have an inadequate response to one or more disease-modifying anti-rheumatic drugs. (See BioWorld Today, Nov. 3, 1998.)

Enbrel has been approved for three indications since then: for reducing signs and symptoms of moderately to severely active polyarticular-course juvenile rheumatoid arthritis, for reducing signs and symptoms of active arthritis in patients with psoriatic arthritis, and for treating psoriatic arthritis.

Enbrel, for all its growth, was temporarily stunted (at least in one indication) in March 2001. Immunex stopped Phase II/III trials of Enbrel in chronic heart failure patients when an independent data monitoring board told the company it was not likely that the therapeutic would meet the efficacy endpoints. (See BioWorld Today, March 23, 2001.)

Although psoriasis sits on the horizon, Immunex expects to see Enbrel approved for ankylosing spondylitis and Wegener's granulomatosis before psoriasis finds its way through the FDA, Burge said. Work in those indications is ongoing.

In December, Amgen Inc., of Thousand Oaks, Calif., and Immunex, of Seattle, announced their intent to merge in a deal then valued at $16 billion in stock and cash - the record-setting price for the acquisition mainly based on the revenue-generating power of Enbrel and its potential upside. The merger is pending. (See BioWorld Today, Dec. 18, 2001.)

Enbrel brought Immunex $761.9 million in revenue in 2001, although Immunex said sales were somewhat limited due to supply issues, now addressed. Enbrel generated $216.5 million in sales in the first quarter, but the long-term goal for Enbrel sales is much higher, Burge said - $5 billion annually. To do that, Immunex needs to stay the course and continue the product's growth.

"We're very excited about the results we've seen in psoriasis," Burge told BioWorld Today. "Compared to other drugs studied in psoriasis recently, the results look favorable. We think we are positioned well to move forward in this indication."

Immunex's stock (NASDAQ:IMNX) fell 62 cents Wednesday to close at $19.76.

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