Subcutaneous natalizumab is delivered under the skin at the same dose as giving it into the blood. This means not as much gets into the blood and here there is a suggestion that it may not be as effective when used during pregnancy
Ricigliano VA, Landi D, Boudot de la Motte M, Ciron J, Bourre B, Casez O, Bartolomeo S, D’Aleo G, Fantozzi R, Foschi M, Napoli F, Papeix C, Marfia GA, Maillart E.Mult Scler Relat Disord. 2026;109:107086. doi: 10.1016/j.msard.2026.107086.
Background: Intravenous (IV) Natalizumab (NTZ) extended-interval dosing (EID) in women with multiple sclerosis (WwMS) is safe and effective in controlling disease activity during pregnancy. Recently, a subcutaneous (SC) form of the drug has become available.
Objectives: To assess clinical/radiological relapses in postpartum comparing IV and SC NTZ EID in two groups of pregnant WwMS.
Methods: We retrospectively collected data on pregnancies across French and Italian MS centers. We assessed clinical/radiological activity in postpartum, accounting for the number of administrations during pregnancy and the duration of NTZ washout.
Results: 56 pregnancies were identified (35IV, 21SC). Relapses were rare and not different between groups (p=0.88). Postpartum radiological activity was observed in 10/21 WwMS with SC NTZ (47.6%), versus 5/35 with IV NTZ (14.3%) (p=0.012; OR=5.32[CI:1.41-20.06]). Notably, 50% of all reactivations with SC NTZ occurred with washout between 10 and 12 weeks.
Conclusions: Our study suggests a higher risk of postpartum radiological activity in pregnant WmMS treated with SC NTZ EID, prompting for adaptation of the administration schedule to control disease reactivation.
Source: multiple-sclerosis-research.org