Amgen Inc. on Tuesday received positive word from an FDA advisory panel regarding Enbrel (etanercept), which the committee unanimously endorsed for approval to treat ankylosing spondylitis - arthritis of the spine.

The recommendation signals that the anti-tumor necrosis factor drug could become the first biologic approved to treat the disease, which Amgen said affects about 350,000 people in the U.S. The FDA typically follows the advice of its panels - in this case, the Arthritis Advisory Committee.

"We are pleased with the committee's unanimous positive vote and will work closely with the FDA to bring Enbrel to ankylosing spondylitis patients who, until now, have had limited options in the treatment of the disease," Beth Seidenberg, Amgen's senior vice president of development, said in a news release. "Enbrel has shown significant reduction in pain, as well as improvement in spinal mobility and physical function."

More specifically, data from pivotal Phase III studies showed that patients treated with Enbrel experienced significant and rapid reduction in pain and morning stiffness, along with improved spinal mobility and physical function. Investigators reported that some patients responded to therapy within two weeks and reached maximum relief within two months.

Enbrel, acquired by Thousand Oaks, Calif.-based Amgen as part of its purchase of Immunex Corp., initially was approved almost five years ago to treat moderately to severely active rheumatoid arthritis in patients who had an inadequate response to one or more disease-modifying antirheumatic drugs. (See BioWorld Today, Nov. 3, 1998.)

Since then, the drug has been approved for three follow-on indications - juvenile rheumatoid arthritis, active arthritis in psoriatic arthritis patients and psoriatic arthritis. Enbrel is designed to bind to tumor necrosis factor and render it biologically inactive, resulting in a reduction in inflammatory activity.

The drug remains in Phase III development for psoriasis.

Amgen paid about $16 billion in stock and cash for Seattle-based Immunex, in large part to gain access to Enbrel's sales potential. It generated $274 million in first-quarter sales for the period ended March 31, with full-year sales figures projected between $1.2 billion and $1.4 billion. In 2002, full-year sales of the drug totaled $802 million. (See BioWorld Today, Dec. 18, 2001.)

Amgen shares North American marketing duties with Madison, N.J.-based Wyeth, which markets Enbrel on its own outside North America. Immunex, now a wholly owned subsidiary of Amgen, manufactures the product.

Other biologic-based inflammatory disease drugs that compete in some indications with Enbrel include Remicade (infliximab, from Centocor Inc.) and Amevive (alefacept, from Biogen Inc.), with Raptiva (efalizumab, from Genentech Inc. and XOMA Ltd.) still in development.

Amgen's stock (NASDAQ:AMGN) gained 93 cents on the news Tuesday to close at $65.05.