To Örebro University

Background: Alemtuzumab (ALZ) is an approved disease-modi-fying therapy (DMT) for relapsing-remitting multiple sclerosis (RRMS). Post-marketing surveillance is important to assess the long-term safety and effectiveness in a real-world setting. ALZ has therefore been included into the Swedish post-market surveillance study “Immunomodulation and Multiple Sclerosis Epidemiology Study” (IMSE) upon launch in Sweden (March 2014).

Objectives: To track effectiveness and long-term safety of ALZ in a real-world setting, with focus on patients treated with ALZ for at least 36 months.

Methods: Swedish MS patients are registered into the nationwide Swedish MS Registry (NeuroReg). IMSE 3 includes all patients starting ALZ treatment with annual clinical measures obtained from NeuroReg; 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 Dimension Test (EQ-5D) and Visual Analogue Scale (VAS).

Results: A total of 118 patients (59% female; 95% RRMS) were included in IMSE 3 between March 2014 and June 2020. Out of 118 patients, 93 had been treated for at least 36 months (62% female), of which 10 patients had switched to another DMT. Mean age at treatment start for patients treated ⩾ 36 months was 34 years and mean treatment duration was 54 months. Mean number of drugs prior ALZ initiation was 2.4. Most of the patients (40%, n=37) switched to ALZ from natalizumab or were treatment naïve (13%, n=12) prior ALZ. The mean num-ber of relapses was reduced from 0.72 one year before ALZ initiation to 0.10 during the first treatment year, followed by 0.08 the second treatment year and 0.06 the third year of ALZ treatment (n=79, 15% missing data). In patients treated ⩾ 36 months significant improvements in mean baseline compared to 36 months were seen for MSSS (3.3 ± 2.7 to 2.3 ± 2.3, n=44) and EQ-5D (0.7 ± 0.3 to 0.8 ± 0.3, n=50), while SDMT showed significantly worsened results after 36 months (64.8 ± 17.5 to 56.2 ± 12.7, n=59). EDSS, MSIS-29 and VAS scores remained stable. A total of 36 adverse events were reported to the Swedish Medical Products Agency, 13 events were classified as serious and 23 events as non-serious. Two patients died during ALZ treatment, one of which was associated to ALZ treatment, and died in association with the first ALZ treatment cycle due to fulminant viral hepatitis.

Conclusions: Patients treated with ALZ for at least 36 months improved or remained stable across all effectiveness measures except SDMT. Continued follow-up is needed to address long term effectiveness and safety of ALZ.