Clinical implications of natalizumab Fab-arm exchange in patients with multiple sclerosis
Liza M.Y. Gelissen·the NEXT-MS study group·Alyssa A. Toorop·Martijn T. Wijburg·Emma C. Tallantyre·Ninotska I.L. Derksen·Floris C. Loeff·Joep Killestein·T. Rispens·Zoé L.E. van Kempen·Stefan P. H. van den Berg
Natalizumab, a monoclonal antibody used to treat multiple sclerosis, can undergo Fab-arm exchange (FAE) with endogenous IgG4, resulting in a monovalent form with reduced avidity and presumed lower potency than the parental bivalent form. Levels of bivalent and monovalent natalizumab depend on the ratio of endogenous IgG4 to total natalizumab, which varies substantially between individuals. The clinical relevance of natalizumab FAE remains unknown. This study investigated the potential clinical i