Background Natalizumab is effective in relapsing remitting multiple sclerosis (RRMS) treatment, although it is associated with serious adverse events that may require therapy discontinuation.
Purpose To assess the reasons for discontinuing natalizumab treatment in patients diagnosed with RRMS, and to estimate the length of these treatments.
Material and methods An observational retrospective study was conducted from December 2007 to June 2016. Patients who received at least one dose of natalizumab in our hospital were included. Collected data, obtained from medical records, were: sex, age, Expanded Disability Status Scale (EDSS), reasons for treatment discontinuation and treatment duration. When natalizumab was discontinued because of the risk of developing progressive multifocal leukoencephalopathy (PML), John Cunningham virus antibody index value was recorded at baseline, after 2 years of therapy and when natalizumab was discontinued. This index classified results as positive or negative until 2012, when the reference laboratory set the numeric value (≤0.9, >0.9≤0.5, >1.5).
Results 54 patients with EDSS ≤5 received at least 1 natalizumab dose. 7/54 patients without follow-up in our hospital were excluded. On completion of the study, 19/47 patients (average age 31.3±8.6 years, 14/19 women) discontinued natalizumab. Median EDSS at the start of treatment was 3.2 (1.9–4.0). Median EDSS when treatment was discontinued was 3.3 (1.3–5.0). Reasons for natalizumab discontinuation were:
Risk of developing PML (9/19). Index value at baseline: 4/9 patients positive, 2/9 negative, 3/9 not available. Index value 2 years after starting natalizumab: 5/9 patients positive, 1/9 negative, 3/9 not available. Index value when natalizumab was discontinued: 9/9 patients showed positive status (≤0.9, 1/9; >0.9≤1.5, 1/9; >1.5, 6/9; 1/9 no numerical value recorded). There was no PML.
Disease progression to secondary progressive multiple sclerosis (3/19).
Anti-natalizumab antibodies (5/19). 4/5 patients reported adverse events: 3/4 infusion reactions, 1/4 paradoxical reaction to natalizumab.
Start of breast cancer chemotherapy (1/19).
Patient´s requirement (1/19).
Average natalizumab treatment duration was 2.3±1.6 years. 10/19 patients received natalizumab for over 2 years.
Conclusion Despite the fact that there was no PML in our hospital, the main reason for discontinuing natalizumab was the increased risk of developing PML, which increased with treatment duration. Adverse events requiring natalizumab discontinuation only appeared in patients with anti-natalizumab antibodies. Average duration of treatment was slightly over 2 years.
No conflict of interest
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