Real-world evidence and patient preference for subcutaneous versus intravenous natalizumab in the treatment of relapsing-remitting multiple sclerosis - initial results from the observational SISTER study.

Background: The consideration of patient preference for a certain drug route of administration (RoA) plays an important role in promoting patient adherence in chronic diseases. Natalizumab is an established treatment for relapsing-remitting multiple sclerosis (RRMS) and can be administered as intravenous (IV) infusion or subcutaneous (SC) injection developed to enable a shorter and easier administration versus IV RoA.

Study objectives: Primary objective is to compare patients' preference for RoA and satisfaction with SC versus IV natalizumab at baseline and subsequent visits up to 12 months. Secondary objectives include drug utilization, clinical outcomes, safety, and treatment satisfaction in a usual care setting.

Design and methods: SISTER (Subcutaneous: Non-Interventional Study for Tysabri Patient Preference - Experience from Real World) is an ongoing, prospective, observational study where natalizumab is utilized according to local label. RRMS patients are included in three natalizumab cohorts: Patients switching from current IV to SC administration (switcher) and patients newly starting natalizumab on either SC or IV route (starter SC/IV). This interim analysis includes 262 patients (184 switchers, 39 SC starters, and 39 IV starters), median observation period was 9 months.

Results: 80.8% IV starters and 93.9% SC starters reported at baseline that they prefer the assigned RoA. Although initial satisfaction with chosen RoA was maintained over time from baseline through Month 12 in all three cohorts, the wish for change of the current RoA after 6 and 12 months was more frequently expressed among IV starters than in either SC cohort. Consistently, six patients (23.1%) starting with IV changed their RoA from IV to SC route.Mean global treatment satisfaction according to TSQM-II score at baseline remained high in the switcher group and increased through Month 12 in both IV and SC starter cohorts.

Conclusion: Based on current data, there is a trend toward patients' preference for the natalizumab SC route over the IV route, which provides valuable insights into patients' preference for natalizumab RoA in routine care and complements available data from clinical studies with real-world data on SC natalizumab.

Trial registration: This observational (non-interventional) study was registered in the local German PEI register for non-interventional studies (NIS-No. 611) and in the international CTgov register (NCT05304520).