Background Natalizumab is indicated in relapsing-remitting multiple sclerosis (RRMS) that remains highly active despite treatment with interferon B and glatiramer acetate, and in rapidly evolving severe RRMS.

Purpose To analyse the effectiveness, safety and results in comparison with the reference clinical trial (CT) in natalizumab patients.

Material and methods Retrospective observational study including patients on natalizumab at the time of data collection (August 2014). Variables included: demographics, time from diagnosis, time with natalizumab, indication, previous treatments, pre/post disability (EDSS), outbreaks before/after change, JC virus antibodies, adverse reactions (ADRs), discontinuations and causes.

Data were obtained from medical records and the electronic prescription software.

Results We analysed 24 patients. 58.3% were women. Mean age was 37.8 years, median time from diagnosis 9.3 years and time on natalizumab 36.6 months.

Previous treatments received were: 13/24 interferon B 1A SC (INF), 10/24 INFB 1A IM, 10/24 glatiramer acetate (GA), 3/24 INFB 1B, 1/24 fingolimod, 1/24 azathioprine and 1 no immunomodulators.

Before natalizumab, mean EDSS was 4.3. EDSS after treatment was 4.6.

33.3% patients had JC + antibodies.

11 patients reported ADRs: 5 infections, 4 skin disorders, 4 fatigue, 3 headaches, 2 insomnia and 1 diarrhoea.

Mean flare-ups before changing were 2.1. Only 6 patients had flare-ups during treatment.

Conclusion Our baseline characteristics and selected variables were not always comparable with the reference CT. Moreover, our small sample size and the daily clinical practice characteristics of our patients made an exhaustive comparison difficult. However, as in the CT, our population presented a maintained EDSS, with a decrease in outbreaks and the ADRs were consistent with the most frequent observed in the CT.

With these results, and according to the published studies,^1,2 we have demonstrated that natalizumab is an effective alternative to immunomodulators for non-responders.

Notified ADRs in our population are consistent with the known safety profile.

References and/or Acknowledgements

1. Polman CH, et al. NEJM 2006

2. O’Connor P, et al. Neurology 2014

References and/or AcknowledgementsNo conflict of interest.