Researcher Annie W. Chiu, B.S. (National Institute of Neurological Disorders and Stroke, Bethesda, Md.) and colleagues make use of that fact that MS patients develop contrast-enhancing brain lesions that MRIs can detect before the patient presents relapse symptoms. The disease is believed to get worse after these relapses. "Many clinical studies have demonstrated the ability of interferon beta to reduce contrast-enhancing lesions," write the researchers. "However, little is known regarding the heterogeneity of the MRI response profiles between patients or within an individual patient over time."

Chiu and colleagues studied 15 MS patients who received monthly MRIs and clinical examinations during two treatment periods. The first was a 6-month pretreatment phase, and the second was a 36-month treatment phase where each patient received 250-microgram injections of interferon beta under the skin every other day.

The study resulted in 8 patients (53.3%) classified as responders due to their 60% reduction in the number of lesions found at each six-month period. The seven non-responders, however, consisted of three who experienced only a brief period of lesion reduction followed by no further reduction and two who never met the 60% percent level of reduction during the 6-month treatment period but reached and maintained a 60% or more reduction afterward. The researchers also noted at least one clinical exacerbation during the treatment face in three responder-group patients and in all seven patients in the non-responder group.

"To our knowledge, our descriptive study provides for the first time a detailed long-term analysis of MRI patterns of patients undergoing long-term interferon beta-1b therapy," conclude Chiu and colleagues. "The results show that on close monthly MRI inspection, approximately half of the patients fail therapy from an MRI perspective."

The researchers add: "Also, we show that an additional small proportion of patients may not be necessarily recognized as MRI non-responders during the first semester [six months] of therapy, and frequent radiological monitoring is advised during the first year of therapy. Multiple MRIs, beyond the first six months of therapy, also disclose a small proportion of patients with a delayed but eventually sustained response to interferon beta and provide compelling information regarding the clinical outcome of patients during the course of a longer trial."

Heterogeneity in Response to Interferon Beta in Patients With Multiple Sclerosis
Annie W. Chiu, BS; Nancy Richert, MD, PhD; Mary Ehrmantraut, MS; Joan Ohayon, MSN; Shiva Gupta, MD; Giuseppe Bomboi, MD; Deeya Gaindh, AB; Fredric K. Cantor, MD; Joseph A. Frank, MS, MD; Henry F. McFarland, MD; Francesca Bagnato, MD, PhD
Archives of Neurology (2008). 66[1].
doi:10.1001/archneur.66.1.noc80047
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