A new, small study by the government suggests that long-term therapy with interferon may have a limited beneficial effect on what are known as "black holes" in people with MS.1 These are areas of lesions in the central nervous system caused by the disease and viewed as highly contrasted images on magnetic resonance imaging (MRI) scans.
Questions to be Answered
While it's well known that interferon beta "reduces formation of contrast-enhanced lesions and … black holes on MRI" in people with MS, "questions remain" about the effectiveness of the medication after black holes have formed, wrote Francesca Bagnato, MD, and her colleagues at the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health.
More specifically, the team wanted to find out whether or not interferon had any effect on the duration of these black hole lesions. Shortening their duration, they hypothesized, may help reduce the formation of more permanent lesions on the brain and spinal cord. These permanent lesions, experts say, reflect areas of irreversible nerve fiber loss and permanent damage.
This study, involving data on six patients—all women—with relapsing MS, was a follow-up to a shorter, preliminary study published by the researchers three years ago.2 The previous study also examined the effect of interferon-beta therapy on black-hole lesions, there were still questions that remained.
Lesions Analyzed Before and During Treatment
For the latest retrospective research, Bagnato and her colleagues analyzed the MRI scans of the patients taken in the 36-month period immediately before treatment with interferon beta-1b (Betaseron), as well as for a 36-month period after therapy was begun. Each MRI exam had been given once per month.
The researchers identified a collective total of 156 new black holes, as seen on MRI before treatment was given, and 31 new black holes during the treatment phase. They also discovered that the duration of new black holes that appeared while these patients were on interferon therapy was not shorter than the duration of black holes that had arisen before treatment. However, "repeated administration of the drug did significantly decrease the rate of black hole formation, thus protecting the brain tissue from accumulating degenerative lesions," wrote Bagnato and her fellow researchers.
One theory behind why interferon treatment had no effect on the duration of these black holes is that it cannot change the pathological process of MS, even though fewer black holes appeared during treatment, Bagnato and her team speculated.
Can Treatment Tame Black Hole Formation?
They did admit, however, that it's not known whether interferon beta-1b can promote the formation of less aggressive new black holes, or faster recovery from them. "Knowing this would be of great importance," the research team concluded. "This would allow one to properly establish the role of interferon beta-1b (or any other neuroprotective drug of the central nervous system) for patients with MS."
In the meantime, Bagnato and her fellow investigators stressed, larger studies are needed to confirm the findings.
"The sample size is small, but the length of the longitudinal follow-up (i.e., 72 months) represents a robust and valid data set for describing the course of MS during both the natural history phase and therapy phase," the authors wrote.
The Interferons for MS
Betaseron is one of three interferon-based therapies available as therapy options for people with multiple sclerosis. The others are known as Avonex (interferon beta-1a) and Rebif (interferon beta-1a).
Avonex comes as a prefilled syringe for intramuscular injection. As other interferon-based therapies, this is a manmade form of interferon, a type of protein that helps the immune system perform its functions properly, among other things.3
Betaseron is also a type of interferon that occurs naturally in the body. It also comes as a syringe, for subcutaneous injection, to treat relapsing forms of MS, and is designed to reduce the numbers of disease flare-ups that may occur.4
Rebif is also available as a prefilled syringe for subcutaneous injection, and is prescribed to treat the symptoms of relapsing MS. It, too, is a synthetic form of interferon.5
1. Bagnato F, Gupta S, Richert ND et al. Effects of interferon beta-1b on black holes in multiple sclerosis over a 6-year period with monthly evaluations. Arch Neurol 2005 Sep 12;[Epub ahead of print].
2. Bagnato F, Jeffries N, Ohayon J et al. A 36-month longitudinal study on the evaluation of the effect of interferon beta in the duration of black holes in multiple sclerosis. Mult Scler 2002;8(Suppl 1):S3.
3. Biogen Idec. Avonex Prescribing Information. Available at: http://www.avonex.com/msavProject/avonex.portal/
_baseurl/threeColLayout/SCSRepository/en_US/
avonex/includes/footer/prescribe_info_med_guide.xml. Accessed September 19, 2005.
4. Berlex. Betaseron Prescribing Information. Available at: http://www.berlex.com/html/products
/pi/Betaseron_PI.pdf. Accessed September 19, 2005.
5. Serono/Pfizer. Rebif Prescribing Information. Available at: http://www.rebif.com/assets/pdfs/Rebif_PI.pdf. Accessed September 19, 2005.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications. John is a member of the American Medical Writers Association (AMWA).
