By Lisa Seachrist

Washington Editor

Following the January recommendations of an advisory committee, the FDA issued Immunex Corp. an approvable letter for the company¿s plans to market its chemotherapy drug, Novantrone, as treatment for multiple forms of multiple sclerosis (MS).

The letter brings the drug one step closer to an expanded label for the treatment of worsening forms of MS. The agency and Seattle-based Immunex must agree on the final labeling and other details before the drug is cleared for marketing.

¿Novantrone will be available for patients in a matter of months,¿ said Tim Warner, media spokesman for Immunex. ¿We¿re being cautious in our estimates of when the drug will be approved. Only the FDA knows the answer to that.¿

Warner said the FDA appears likely to follow the recommendation of the advisory panel and approve the drug for both worsening relapsing-remitting MS and the progressive form of the disease. The company was originally requesting approval for the drug¿s use in progressive forms of the disease; however, the FDA¿s Peripheral and Central Nervous System Drugs Advisory Committee maintained there was no good definition of the various phases of MS and recommended the drug be approved for any form of MS that was worsening.

Immunex expects to have the drug ready for distribution to patients as soon as the FDA OKs its sale.

¿From a sales and marketing standpoint, this will be a virtual flick of the switch,¿ Warner said.

Novantrone (mitoxantrone HCL) has been on the market in the U.S. since 1987 for the treatment of acute myelogenous leukemia. In 1997, the company received approval to expand the label to include the treatment of the pain associated with prostate cancer. Because the drug suppresses the activity of T cells, B cells and macrophages, Immunex explored the drug¿s utility in treating MS.

MS is a chronic debilitating autoimmune disease affecting the central nervous system. It can take several forms and as many as 350,000 people in the U.S. suffer from MS. The severity of the disease ranges from periodic episodes of disability followed by relatively normal functioning, known as relapsing-remitting, to a relentlessly progressive disability.

In recommending the drug for use in worsening MS, the advisory panel in January recognized the fact that half of all patients with relapsing-remitting disease will gradually see their disease become a progressive form within 10 years, and it is difficult to know exactly when the disease moves from one stage to another. (See BioWorld Today, Jan. 31, 2000, p. 1.)

Several therapies exist for the relapsing-remitting form of the disease, but to date no therapy has been approved to treat the progressive form of MS. With the approvable letter, Novantrone is now likely to be the first.

¿This would be an entirely new opportunity for neurologists and their patients suffering from worsening MS,¿ Warner said.

Immunex¿s stock (NASDAQ:IMNX) closed Thursday at $220.937, up $1.937.