To Örebro University

Background: Subcutaneous peginterferon beta-1a (PegIFN) was approved for relapsing-remitting multiple sclerosis (RRMS) in Europe 2014. The clinical trial program showed that PegIFN reduced the relapse rate and proportion with disability progression compared to placebo. At its launch in Sweden, PegIFN was included in the Swedish “Immunomodulation and Multiple Sclerosis Epidemiology Study” (IMSE 6), providing possibilities to track long-term effectiveness and safety in a population-based setting.

Objectives: To follow-up the long-term effectiveness and safety of PegIFN treatment in Swedish patients in a real-world context.

Methods: Data was obtained from the nationwide Swedish Neuro Registry (NeuroReg) between June 2015 and May 2020. Effectiveness measures were assessed using the Wilcoxon Signed Rank Test and drug survival using the Kaplan-Meier curve.

Results: A total of 364 patients (78% female; 87% RRMS; mean age at treatments start 43 years) were followed up to 57 months (mean 20 months), of which 200 (55%) patients had been treated for at least 12 months. The majority of the patients had switched from other injectables (164 patients, 45%) or were treatment naïve (90 patients, 25%) prior to treatment with PegIFN. Over the dura-tion of the follow-up, 68% (247/364) patients discontinued their PegIFN treatment for various reasons (60% adverse events, 24% lack of effect) and switched mainly to rituximab (105 patients, 43%). The overall drug survival was 32%, 40% for men and 30% for women. The one- and two-year drug survival rate was 57% and 40%, respectively. The mean number of relapses were reduced from 0.35 one year before treatment start to 0.11 one year after (35% missing data). All clinical effectiveness measures (Extended Disability Status Scale (EDSS), Multiple Sclerosis Severity Scale (MSSS), Multiple Sclerosis Impact Scale (MSIS-29), European Quality of Life – 5-Dimension test (EQ-5D), Visual Analogue Score (VAS) and Symbol Digit Modalities Test (SDMT)) remained stable. Statistically significant changes were observed in SDMT (p=0.027). A total number of 18 adverse events (6 serious) were reported to Swedish Medical Product Agency.

Conclusions: These findings are consistent with PegIFN being a safe disease modifying treatment, however, a relatively high pro-portion of patients switched due to adverse events. All clinical effectiveness measures remained stable in patients treated with PegIFN for at least 12 months in this nationwide population-based real-world study. Longer follow up is needed to address the long-term effectiveness.