News Release

New Three Year Follow-up Data Of Novantrone In Multiple Sclerosis

Peer-Reviewed Publication

Immunex Corporation

Positive Response and Safety Profile of NOVANTRONE Confirmed over a Three Year Period In Study Treating People with Secondary Progressive Multiple Sclerosis

TORONTO, ONTARIO, CANADA - Patients with secondary progressive multiple sclerosis (MS) treated with NOVANTRONER (mitoxantrone for injection concentrate) experienced sustained reduction in their number of attacks, and delay in their disability progression, compared to patients treated with placebo. The new results, involving patients treated for two years and then followed for an additional year, were presented today by researchers at the 51st Annual Meeting of the American Academy of Neurology (AAN).

These findings follow the previously announced two year study results, which were reported at the September 1998 Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS). This Phase III, multicenter, placebo-controlled, randomized, observer-blind study of 194 patients with secondary progressive MS assessed the effects of NOVANTRONE on attacks and disease progression. In this study, patients taking NOVANTRONE had fewer attacks and less deterioration of their neurologic impairment. These clinical data were corroborated by positive magnetic resonance imaging (MRI) data.

The study compared two doses of NOVANTRONE -- 12 mg/m2 and 5 mg/m2 - with placebo. Each treatment was administered by short, IV infusion once every three months for two years. Other treatments currently approved for the relapsing-remitting form of MS require a subcutaneous or intramuscular self-injection on a daily or weekly basis.

"Today's third-year follow-up data presentation confirms the earlier findings of this Phase III study," said Peggy V. Phillips, senior vice president, pharmaceutical development for Immunex. "The next step is to file data with the FDA to seek an expanded label for the use of NOVANTRONE in MS."

Results of the featured follow-up data showed a marked difference in the number of patients who had an Expanded Disability Status Scale (EDSS) deterioration of one point when measured from baseline to month 36. Only 17% of the patients in the 12 mg/m2 arm and 24% of patients receiving 5mg/m2 experienced a deterioration of one point compared to 44% in the placebo arm. The EDSS is the standard clinical rating scale used to evaluate disability progression in MS clinical trials. It measures disability based on the level of neurologic impairment by rating a patient's level of function from zero (normal neurological exam) to 10 (death due to MS), with every half-point increase on the scale representing a progressive deterioration of ability.

Over the course of the one year of post-therapy follow-up, more patients remained without relapse in the 12 mg/m2 (66%) and 5mg/m2 (69%) arms than those in the placebo arm (51%). Patients in both the groups treated with NOVANTRONE also had a smaller number of relapses in the third year, with a mean number of relapses of 0.48 for the 12 mg/m2 dosage and 0.42 for the 5mg/m2 dosage compared to 0.74 for placebo.

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), 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 afflicts more than 300,000 Americans and more than one million people worldwide. The symptoms of MS result when inflammation and breakdown occur in myelin, the fatty substance that insulates the nerve fibers of the brain and spinal cord. This substance helps conduct the flow of nerve impulses to and from the brain. In people with MS, the myelin is damaged, causing patches of scar tissue, or "sclerosis," which interferes with the body's ability to transport messages from the brain to body parts, thereby inhibiting body functions and movement. This can result in a variety of symptoms that range from numbness in the limbs to complete paralysis.

Approximately 120,000 MS patients have a form of the disease classified as secondary progressive. These patients are initially diagnosed with relapsing-remitting disease, in which their symptoms flare up and then ease or even disappear for months or years. Eventually, the neurological function of patients who develop secondary progressive MS begins to steadily worsen as flares become more frequent and severe, and recovery is incomplete. There are currently no approved treatments in the United States for people with secondary progressive MS.

NOVANTRONE has been studied in MS preclinically and clinically for more than a decade. The follow-up results released today are consistent with the outcomes from earlier trials. Initial studies showed NOVANTRONE helped prevent disease relapse and progression in mice. These preclinical studies led to further studies of NOVANTRONE in patients with MS. Several Phase I and II trials were conducted that showed a reduction in new lesions on MRI, as well as reductions in the number and severity of relapses in patients treated with NOVANTRONE.

NOVANTRONE is currently marketed to treat pain in patients with advanced hormone-refractory prostate cancer in combination with corticosteroids and for initial therapy of acute nonlymphocytic leukemia. It is not approved for use in MS patients. Full prescribing information for NOVANTRONE can be obtained by calling 1-800-IMMUNEX or visiting www.immunex.com.

Immunex holds the marketing rights for NOVANTRONE in the United States. Wyeth-Ayerst International, which is a division of American Home Products, markets NOVANTRONE outside the United States.

###

Immunex Corporation is a biopharmaceutical company dedicated to developing immune system science to protect human health. The company's products offer hope to patients with cancer, inflammatory and infectious diseases.

American Home Products Corporation owns a majority interest in Immunex. AHPC is one of the world's largest research-based pharmaceutical and health care products companies and is a leading developer, manufacturer and marketer of prescription drugs and over-the-counter medications. It is also a leader in vaccines, biotechnology, agricultural products and animal health care.

NOTE: This news release contains forward-looking statements that involve risks and uncertainties, including risks associated with clinical development, regulatory approvals, product commercialization and other risks described from time to time in the SEC reports filed by Immunex, including the most recently filed Form 10-K.

An electronic version of this news release - as well as additional information about Immunex of interest to investors, customers, future employees and patients - is available on the Immunex home page at www.immunex.com.



Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.