Till Örebro universitet

Introduction: Cladribine is a deoxyadenosine analogue prodrug targeting proliferating B- and T-lymphocytes. Cladribine tablets (CladT) are administered in two courses, 12 months apart, for patients with remitting multiple sclerosis (RMS). CladT is included in the Swedish post-market surveillance study “Immunomodulation and Multiple Sclerosis Epidemiology substudy 10” (IMSE 10).

Objectives/Aims: To assess safety and effectiveness of CladT with focus on 24 months treatment outcomes.

Methods: Data on 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) scores, and relapses and Adverse Events (AEs) were collected from the nationwide Swedish Neuro Registry (NeuroReg). Effectiveness measures and relapse rates were assessed using Wilcoxon Signed Rank Test.

Results: A total of 287 CladT exposed Persons with MS (PwMS) have been included in IMSE 10 since the launch of CladT in April 2018. In this cohort 90.6% remained with CladT while 27 patients (9%) discontinued treatment at any time after initiation. The most common reason for discontinuation was lack of effect (78%). A total of 24 AEs were reported to the Swedish Medical Products Agency, of which 10 were serious. The most common AE reported were infection and infestation.A total of 137 patients had CladT exposure for ⩾24 months of which 30 % being treatment naïve, 19% switched from Tysabri, 10 % from dimethyl fumarate and 7% from rituximab, prior CLadT treatment. In this cohort 91.9% remained with CladT. The ⩾24 months’ cohort demonstrated clinical stability with a non-significant trend for improvement in mean MSSS, SDMT, MSIS-29 Psychological/Physical scores compared with baseline. All other outcomes remained stable. The mean annual relapse rate (ARR) decreased significantly (p<0.05) during all treatment years compared to the ARR one-year prior treatment.Lymphocyte levels decreased from a mean of 1.9 x 109/L at treatment start to 1.11 x 109/L at 12 Months and 0.87 x 109/L at 24 months of treatment.

Conclusion: Most PwMS exposed for ⩾24 months to CladT display clinical stability and a tendency for improvement compared with baseline in several of the investigated outcomes. Longer observation times will be needed to assess the effectiveness and safety of CladT beyond 24 month exposure.