Interferon-ß-1b is effective against Secondary/Progressive Multiple Sclerosis and Interferon-ß-1a is effective against Relapsing/Remitting MS, according to results of two studies that appear in the November 7th issue of The Lancet.
In a double-blind, randomized, placebo-controlled study, Dr. Ludwig Kappos. of Univ Hospital in Basel, Switzerland, and colleagues with the European Study Group on Interferon-ß-1b in Secondary/Progressive MS.
They followed a subset of 718 MS patients in the Secondary/Progressive phase of the disease for up to 3 years. The patients received subcutaneous injections of either 8 million IU Interferon-ß-1b or placebo every other day.
"Interferon-ß-1b delayed progression for 9-12 months," Dr. Kappos and colleagues report. "The odds ratio for confirmed progression was 0.65." Treatment with Interferon-ß-1b also lengthened time to becoming wheelchair-bound, and both relapse rate and relapse severity.
In addition, according to editorialist Dr. Donald E. Goodkin, from UCSF, in California, treatment with Interferon-ß-1b reduced the "...number of new MRI lesions and progression of total T2-weighted lesion load."
The researchers say that treatment was generally well tolerated. Injection-site reactions and flu-like symptoms were the most commonly reported adverse events. Dr. Kappos and others report that they halted the study "...after the interim results gave clear evidence of efficacy."
In light of these findings, Interferon-ß-1b "...should immediately be made available for patients with Secondary/Progressive disease, including those who have not experienced superimposed relapse," Dr. Goodkin suggests.
In a second double-blind, randomized, placebo-controlled study, Dr. George C. Ebers of London Health Sciences Centre in London, Ontario, Canada, and colleagues with the Prevention of Relapses and Disability by Interferon-ß-1a Subcutaneously in Multiple Sclerosis Study, followed 560 patients with Relapsing/Remitting MS over the course of 2 years.
Patients were assigned to either placebo or 22 or 44 micrograms of subcutaneous Interferon-ß-1a 3 times weekly.
"The relapse rate was significantly lower at 1 and 2 years with both doses of Interferon-ß-1a than with placebo," the researchers report.
"Time to first relapse was prolonged by 3 and 5 months in the 22 microgram and 44 microgram groups respectively, and the proportion of relapse free patients was significantly increased."
In patients treated with Interferon-ß-1a, Progression in disability was delayed, and Accumulated Disability was reduced. The number of new MRI lesions was also reduced.
Use of Interferon-ß-1a was associated with "...asymptomatic decreases in White Cells, Neutrophils, and Lymphocytes, and raised Aminotransferase values," according to Dr. Ebers and colleagues.
"Follow-up of patients from this study will define more clearly whether the profound effects observed on MRI translate into longer-term clinical benefits,".