FDA review of NOVANTRONE data to be completed within six months

SEATTLE-Immunex Corporation (NASDAQ:IMNX) announced today that the U.S. Food and Drug Administration (FDA) has assigned priority review status to the new drug application (NDA) for NOVANTRONER (mitoxantrone for injection concentrate), indicating that the FDA will act on the application within six months of its date of submission. Immunex filed for expanded labeling for NOVANTRONE for the treatment of patients with secondary progressive multiple sclerosis (MS) on June 7, 1999.

"This is an important milestone in the development of NOVANTRONE as a potential treatment for people with secondary progressive MS," said Peggy V. Phillips, senior vice president, pharmaceutical development for Immunex. "We will continue to work closely with the FDA over the next six months as they evaluate these data."

The results of the pivotal NOVANTRONE Phase III study showed that NOVANTRONE had a statistically significant impact on reduction of relapse rate and delay in disability progression in patients with secondary progressive MS. Additional follow-up data presented at a recent international conference showed that one year after treatment was stopped, patients treated with NOVANTRONE continued to experience a reduction in their number of attacks, and a delay in their disability progression.

In the study, treatment with NOVANTRONE resulted in generally manageable side effects that were primarily mild to moderate. During the two-year trial, the most frequent side effects reported by patients treated in the 12 mg/m2 arm were nausea, alopecia (hair loss), upper respiratory tract infection, urinary tract infection, menstrual disorder, and transient neutropenia (a reduced number of white blood cells).

Multiple sclerosis is a chronic, debilitating disease of the central nervous system that, in its various stages, afflicts as many as 350,000 people in the Unit
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Contact: Lisa Crisera
criseral@immunex.com
206-389-4346
Immunex Corporation
19-Jul-1999