To Örebro University

Background: Subcutaneous peginterferon beta-1a (PegIFN) was approved for relapsing-remitting multiple sclerosis (RRMS) in Europe 2014. Phase II and III studies have shown that PegIFN reduces relapse rate and disability progression. PegIFN were included in the Swedish “Immunomodulation and Multiple Sclerosis Epidemiology Study” (IMSE 6) due to the importance of studying the long-term safety and effectiveness.

Objectives: To follow-up the long-term safety and effectiveness of PegIFN in a real-world setting.

Methods: Data was obtained from the Swedish Neuro Registry (NeuroReg). All clinical measures; Extended Disability Status Scale (EDSS), Multiple Sclerosis Severity Scale (MSSS), Symbol Digit Modalities Test (SDMT), Multiple Sclerosis Impact Scale (MSIS-29), European Quality of Life - 5 Dimensions Test (EQ-5D), Visual Analog Scale (VAS) were assessed using the Wilcoxon Signed Rank Test and drug survival using the Kaplan-Meier curve.

Results: 393 patients (78% female; 86% RRMS) were included in IMSE 6 between June 2015 and April 2021. Mean age at treatment start was 42 years, mean treatment duration was 23 months. 25% were treatment naïve and 47% switched from other injectables prior PegIFN. The one- and two-year drug survival rate was 58% and 41% respectively, and 31% overall. In total, 271 patients discontinued their PegIFN treatment at some time point, mainly due to adverse events (51%) and lack of effect (26%). Most patients switched to rituximab (37%). During the entire treatment period 54% were relapse-free and 8% had only one relapse (36% missing data). In patients treated at least 24 months tendencies of improve-ments were seen for SDMT and EQ-5D. MSIS-PSYCH showed significantly worsened results (21.2 ± 18.6 to 24.3 ± 19.3, n=46). EDSS, MSSS, MSIS-PHYS and VAS scores remained stable. 25 adverse events (AEs) have been reported to Swedish Medical Product Agency (MPA). 6 of these were classified as serious where general disorders and administration site, and skin (33% respectively) were the most common categories. General disorders and administration site were also the most common for non-serious AEs (68%).

Conclusions: NeuroReg proves to function well as a post-marketing drug surveillance platform. All clinical effectiveness measures, except MSIS-PHYS, remained stable in patients treated for at least 24 months in this nationwide population-based real-world study. Longer follow up is needed to address the long-term effectiveness.