Background

Pregnancy management in patients with relapsing-remitting multiple sclerosis (MS) treated by Natalizumab (NTZ) is challenging because of the risk of disease reactivation after treatment discontinuation.

Objectives

To compare clinical disease activity (annual relapse rate) during and after pregnancy among three therapeutic approaches: continuation of NTZ all along the pregnancy and the postpartum, discontinuation of NTZ in the second trimester and discontinuation of NTZ before pregnancy.

Methods

Data were collected from the French MS registry OFSEP (Observatoire Français de la Sclérose en Plaques). We included patients with relapsing-remitting MS who started a pregnancy between 6/2013 and 9/2018 while taking NTZ, or within six months after its suspension. 3 groups were compared : continuation of NTZ throughout pregnancy and postpartum (Group 1), 3 to 6 months of exposure to NTZ during pregnancy (Group 2) and suspension prior to pregnancy (Group 3). Annual relapse rate (ARR) during 2 years (9 months before and 15 months after preganncy onset) was the primaty outcome and effect on EDSS and MRI were secondary end-points.

The main analysis was performed using a negative binomial regression with the follow-up duration as the offset term. Univariate and multivariate anlyses after adjustment for baseline variables (age, EDSS, ARR in the year before starting NTZ, first-line patient on NTZ vs. second-line patient).

Results

117 patients from 27 centers* were included. Baseline mean age was 31,5 y, median EDSS was 2.0 and mean duration of disease was 7,89 y. The mean ARR were respectively 0.078 +/- 0.24 in Group 1, 0.308 +/- 0.43 in Group 2 and 0.456 +/- 0.63 in Group 3 during the observation period and was significantly higher in Groups 2 and 3 as compared with ARR in Group 1 (p=0,007). The risk of relapses was 4 times higher in Group 2 versus Group 1 (p=0,014) and 6 times higher in Group 3 versus Group 1 (p=0,001).

Multivariate analyses did not show any effect of the adjustment variables.

Evaluation of safety outcomes on the mother and the fetus is in progress.

* Investigators: AR, JCO, CD, PB (Bordeaux), SD, BA, AR, AM, CB, JP (Marseille), MD, S Pitton (Nancy), JD (Strasbourg), TM (Dijon), JC, D Biotti (Toulouse), OC, M Vaillant (Grenoble),E Berger (Besançon), D Laplaud (Nantes), G Defer (Caen), I Patry (Corbeil-Essonnes), P Vermersch (Lille), P Labauge (Montpellier), O Bourre (Rouen), B Stankoff (Paris-Saint-Antoine), A Créange (Créteil), P Cabre (Fort-de-France), E Thouvenot (Nîmes), T De Broucker (Saint-Denis), C Papeix (Paris-Salpêtrière), P Clavelou (Clermont-Ferrand), O Gout (Paris-F.Rothschild), A Montcuquet (Limoges), C Lebrun (Nice), O Heinzlef (Poissy) N Maubeuge (Poitiers).

Conclusions

Continuation of Natalizumab during all three trimesters of pregnancy is associated with a lower risk of relapses as compared with discontinuation before the pregnancy or even during the second trimester.

Safety data is being collected.