Personalized Extended Interval Dosing of Natalizumab in Relapsing Remitting Multiple Sclerosis

This a national open label phase IV natalizumab cohort study. Our aim is that the large majority of natalizumab treated RRMS patients who are currently treated with PEID in The Netherlands will continue in this study with a treatment interval ≥6 weeks. We will continue the NEXT-MS study with 24 participating centers. The study duration is two years. This study will contain the PEID group, a control group and a historic control group. Participants will decide in which group they will participate as this is an open label, non-randomized study. We have chosen this design as we expect the large majority of patients wanting a personalized natalizumab treatment for the following reasons. Others and our own study group have studied personalized and extended dosing of natalizumab treatment, all indicating that this is a safe approach. Data from the NOVA trial support this approach. As we see a drastic reduction of PML risk with extended interval dosing there is a growing trend internationally to personalized/extended interval dosing. Furthermore, there is an increasing wish in patients and physicians for personalized treatment to increase patient convenience and lowering costs of expensive medication and healthcare. Based on recent data from the NOVA-trial and data from our preliminary analyses, all patients in the PEID group will continue with personalized dosing with an interval ≥6 weeks. The PEID study group will receive a personalized treatment with the aim of a natalizumab trough concentration of 5μg/ml. If patients do not desire a personalized treatment, they will be asked informed consent for the use of their patient data and for the questionnaires as the control group. As this introduces a bias, the PEID group will be compared to a historical cohort of Amsterdam MS Center. Furthermore, the patients of the control group will be asked to donate blood once for measuring of natalizumab trough concentration. As of April 2021, the European Commission has granted marketing authorization for SC in-jection of natalizumab. As pharmacokinetics and pharmacodynamics between SC and IV ad-ministration resulted in comparable trough natalizumab serum concentration and a4-integrin receptor saturation, patients who desire a switch from IV administration to SC administration will have the opportunity to continue the study in the same study group.