Natalizumab extended interval dosing (EID) is associated with a significant reduction in progressive multifocal leukoencephalopathy (PML) risk compared with standard interval dosing (SID) in the TOUCH® Prescribing Program

Introduction Natalizumab, approved for 300 mg intravenous every-4-weeks dosing, is associated with PML risk. Objectives To determine whether natalizumabEID is associated with reduced PML risk compared with SID. Patients and methods Average dosing intervals (ADIs) were ≥ 3 to 5 to ≤ 12 weeks for EID. The primary analysis assessed ADI in the last 18 months of infusion history. The secondary analysis identified any prolonged period of EID at any time in the infusion history. The tertiary analysis assessed ADI over the full infusion history. Results In primary analyses, median exposure (months) was 44 for SID and 59 for EID. The PML HR (95% confidence interval) was 0.06 (0.01–0.22; P P P = 0.02). Discussion NA. Conclusion In JCV Ab + patients, natalizumabEID is associated with a clinically and statistically significant reduction in PML risk as compared with SID.