October 13, 2003
By Joene Hendry
Doctor's Guide Publishing Limited
The development of neutralising antibodies against interferon beta is associated with significantly higher relapse rates among patients with relapsing-remitting multiple sclerosis, according to researchers in Denmark.
"In patients who are not doing well on interferon beta, the presence of such antibodies should prompt consideration about change of treatment," writes Per Soelberg Sorensen, MD, Copenhagen University Hospital, Denmark and colleagues. They measured neutralising antibodies against interferon beta every 12 months for up to 60 months in 541 patients with multiple sclerosis. The study population was randomly selected from a national multiple sclerosis treatment database containing clinical records of all patients who started treatment with interferon beta between 1996 and 1999. The researchers used antiviral neutralisation bioassays with high, medium, and low sensitivity to measure antibodies in the patients' blood and compared the levels of neutralising antibodies with the patients' outcomes.
The investigators found the presence of neutralising antibodies had a substantial effect on the relapse rate of the study population. During antibody-positive periods, relapse rates were 0.64 to 0.70 while during antibody-negative periods, relapse rates were 0.43 to 0.46. When comparing the neutralising antibody-positive and neutralising-antibody negative periods the odds ratios for the number of relapses ranged from 1.51 to 1.58.
At 12 months after the initiation of interferon beta treatment, the patients who were positive for antibodies had a median time to first exacerbation of 361 days while the patients negative for antibodies had a median time to first exacerbation of 605 days.
Throughout the study period, 27% of the patients in the neutralising-antibody positive group remained free of relapse while 39% of those in the antibody negative group remained relapse free. The development of neutralising antibodies was independent of age, sex disease duration, and progression index at the start of treatment.
The investigators indicate that long-term studies are needed to clarify the correlation between neutralising antibodies against interferon beta and disease progression in patients with multiple sclerosis. Treatment decisions should still be primarily based on clinical outcome, "but in patients with neutralising antibodies a change in treatment would be reasonable if substantial clinical activity is noted," the authors conclude.
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