• Natalizumab biosimilar used safely for MS during pregnancy until week 26 • No relapses occurred during pregnancy or postpartum follow-up • Both mother and infant showed favourable clinical outcomes Natalizumab is a monoclonal antibody used in the treatment of relapsing-remitting multiple sclerosis (RRMS). In the context of pregnancy, MS management becomes particularly challenging due to the risk of disease reactivation if high-efficacy therapies are withdrawn. While increasing evidence supports the continuation of natalizumab in selected pregnant patients, data on natalizumab biosimilar in this setting remain limited. We report the first documented case in Italy of a 31-year-old woman with RRMS treated with a natalizumab biosimilar during pregnancy. After switching from the originator product, the biosimilar was administered every four weeks until the 26th week of gestation. The patient remained clinically stable throughout pregnancy, with no relapses or treatment-related adverse events. Delivery occurred without major complications, and the neonate fully recovered after transient mild asphyxia related to a triple nuchal cord. Natalizumab biosimilar therapy was resumed 10 days postpartum. At 3, 6, and 12 months of follow-up, the patient remained relapse-free, with stable clinical and magnetic resonance imaging findings. Both mother and infant were in good health. This case supports the feasibility of natalizumab biosimilar use during pregnancy and early postpartum in women with RRMS, highlighting the importance of individualised risk–benefit assessment and close monitoring.
Dutto et al. (Fri,) studied this question.