Natalizumab for the prevention of post-partum relapses in women with multiple sclerosis

Objective: Our aim was to evaluate the impact of early redosing of natalizumab after delivery on the risk of post-partum relapses in six women with very active multiple sclerosis (MS). Methods: We undertook a retrospective analysis of data collected prospectively in the Lyon MS Cohort. Results: The annualized relapse rate (ARR) in the year before natalizumab treatment was 4.2 0.4, which decreased to 0.4 +/- 0.6 during the treatment period. The mean time between natalizumab withdrawal and onset of pregnancy was 9 months; one pregnancy was exposed to one infusion. The ARR between natalizumab withdrawal and onset of pregnancy was 1.8 +/- 0.7. Six relapses occurred before onset of pregnancy and seven during pregnancy. Natalizumab was restarted 7.8 days after delivery (between day 2 and 8 for five patients and on day 23 for one). Only one patient, who had restarted natalizumab 2 days after delivery, had a relapse 2 weeks later. The others five patients were relapse free after a mean of 14.2 +/- 9.1 months of follow-up. Conclusion: Despite a high risk of post-partum relapses, early redosing of natalizumab led to a complete disappearance of disease activity in all but one patient. These data suggest that natalizumab could be a good candidate for preventing early post-partum relapses.