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Although the trial was small, the findings reiterate what has previously been shown with natalizumab in larger, prior studies.
Mohammad Taheri, MD
A small, 12-month trial showed that natalizumab (Tysabri, Biogen) displayed superiority to interferon beta (IFN-ß) for patients with relapsing multiple sclerosis (MS) by significantly decreasing disability levels.1
The study found that 80% of those treated with natalizumab experienced a significant decrease in Expanded Disability Status Scale (EDSS) score. Additionally, compared to the control group, the number of relapses was significantly lower in natalizumab patients.
The natalizumab group (n = 25) experienced significant decreases in EDSS compared to the IFN-ß control group (n = 30) in months 10, 11, and 12. In total, 50 patients with relapsing MS were included in the trial, with EDSS score and clinical signs of relapse being assessed on a monthly basis.
“Ninety percent of patients treated with natalizumab experienced no relapses during the study period,” Mohammad Taheri, MD, of the department of Medical Genetics at Shahid Beheshti University of Medical Sciences, in Tehran, and colleagues wrote. The remaining 2 patients (10%) in this group experienced a single relapse. Relapses were reported in all IFN-β-treated patients, with 36.6% experiencing 1 relapse and 63.3% experiencing 2 relapses.
“Moreover, despite higher primary EDSS scores in natalizumab-treated patients, EDSS score at month 12 was significantly lower in these patients compared with [the] control group which further shows the efficacy of natalizumab.”
At baseline, the natalizumab group (5.45; standard deviation [SD], 0.15; range, 5 to 5.5) had a higher EDSS mean score than the IFN-ß control group (4.52; SD, 1.09; range, 3 to 6). From the study start to month 12, the mean EDSS score decreased 1.47 points in natalizumab-treated patients and increased 0.58 in the IFN-β group.
EDSS score in month 12 was significantly different from EDSS scores in month 1 to month 7 (natalizumab: range, 5.45 to 4.85; control: range, 4.52 to 4.87) both in natalizumab (3.98; SD, 1.37) treated patients and the control group (5.10; SD, 1.18).
In this study, all natalizumab-treated patients were unresponsive to former treatment with IFN-β, having experienced ≥2 relapses in the year before. IFN-β was discontinued in this group of patients, and thus these findings, the authors note, provide evidence for the effectiveness of natalizumab as a single second-line treatment.
Notably, as Taheri and colleagues pointed out, previous research has suggested similar findings with natalizumab. In the 2005 revisions to the McDonald Criteria, Polman et al. found that natalizumab is capable of decreasing the risk of continuous progression of disability and the frequency of relapses in patients with relapsing MS.2
Additionally, in 2006, Rudick et al. administered natalizumab along with IFN-β in patients with relapsing MS and reported a similar superiority with natalizumab than IFN-ß alone, ultimately finding that the combination therapy was associated with a lower annualized rate of relapse over a 2-year period (0.34 vs 0.75, P <.001).3
“In a randomized, double-blind trial, Miller et al. have compared [the] effectiveness of two doses of natalizumab (3 and 6 mg/kg) with placebo and found significant decreases in the mean number of new lesions in both natalizumab groups,” Taheri and colleagues explained. “Therefore, our results in Iranian MS patients are consistent with the previous studies in other populations.”
1. Mazdeh M, Hosseini S, Taheri M, Ghafouri-Fard S. The effect of natalizumab on disability score and relapse rate of multiple sclerosis patients: a prospective cohort study. Clin Transl Med. 2018;7:38. doi: 10.1186/s40169-018-0216-3
2. Polman CH, Reingold SC, Edan G, et al. Diagnostic criteria for multiple sclerosis: 2005 revisions to the “McDonald Criteria.” Ann Neurol. 58(6):840-846. doi: 10.1002/ana.20703
3. Rudick RA, Stuart WH, Calabresi PA, et al. Natalizumab plus interferon beta-1a for relapsing multiple sclerosis. N Engl J Med. 354(9):911-923. doi: 10.1056/NEJMoa044396