By Randall Osborne

West Coast Editor

Immunex Corp.¿s home-run rheumatoid arthritis drug, Enbrel (etanercept), is stepping up to the plate a fourth time, with the filing of a supplemental biologics license application for psoriatic arthritis.

Asking for fast-track status with the FDA, Immunex also is filing for regulatory approval in Canada for the same indication, along with data from Phase II and Phase III studies. Enbrel would be used with or without methotrexate.

¿There are no currently approved treatments,¿ said Robin Shapiro, director of public affairs for Seattle-based Immunex. An inflammatory disease like rheumatoid arthritis, psoriatic arthritis ¿combines the devastating effects of bad arthritis ¿ joint destruction and overall chronic fatigue ¿ with psoriasis, [characterized by] skin lesions that are very disfiguring.¿

Shapiro said ¿a lot of people don¿t know about the disease,¿ and Immunex has estimated the market at about 300,000 patients in the U.S., although the National Psoriasis Foundation believes the number is ¿a lot higher,¿ she said. Physicians have been using the nonsteroidal anti-inflammatory drugs and disease-modifying anti-rheumatic drugs that also are used against RA.

Enbrel, a tumor necrosis factor inhibitor, was first approved for moderate to severe active RA in patients with an inadequate response to DMARDs. Next, the FDA gave Enbrel the nod for moderate to severe active polyarticular-course juvenile RA not responding to DMARDs. Last year, Enbrel was approved for reducing signs and symptoms of RA, and inhibiting structural damage in patients with moderately to severely active RA. This approval removed the DMARDs requirement, and more than tripled the size of the drug¿s market, adding some 700,000 patients. (See BioWorld Today, June 8, 2000.)

¿The market right now is about 1 million,¿ Shapiro said.

The psoriatic arthritis indication would add about 300,000 more patients, Immunex said. Enbrel, partnered with Wyeth-Ayerst, a division of American Home Products Corp., of Madison, N.J., is the only TNF inhibitor approved for use with or without methotrexate.

The drug has undergone hard times lately. It failed in a Phase II/III trial in chronic heart failure and an independent data monitoring board recommended Immunex halt the study. (See BioWorld Today, March 26, 2001.)

¿We¿re still bringing in the data and analyzing it in-house to see what was happening there,¿ Shapiro said.

Still, Enbrel sales reached $652.4 million in 2000, up from $366.9 million in 1999, and accounted for 76 percent of the company¿s total revenue. Immunex was expected to disclose its latest earnings after the market closed Tuesday, with a conference call to discuss the results today.

The potential competitor with Enbrel in the psoriatic arthritis arena is Malvern, Pa.-based Centocor Inc.¿s Remicade (infliximab), but it¿s not expected to start enrolling patients in its Phase III study until the first quarter of next year, and Immunex is on course to present final data from its Phase III trial of Enbrel at a scientific meeting later this year. (See BioWorld Today, June 12, 2001.)

Concerns about manufacturing shortfalls of Enbrel are being handled, Shapiro told BioWorld Today. Contruction on a new facility is under way, and ¿we will up to double our capacity in mid-2002,¿ she said.

Meanwhile, the company started an Enbrel ¿enrollment plan¿ last November.

¿We projected there would be more patients, and as supply is available, new patients are brought on,¿ Shapiro said.

Immunex¿s stock (NASDAQ:IMNX) closed Tuesday at $15.04, up 45 cents.

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