A retrospective data analysis of multiple sclerosis (MS) patients under the disease-modifying treatment of cladribine: Assessing effectiveness and side effects in a real-world cohort

Abstract

The objective of this study was to evaluate the clinical efficacy, adverse events and predisposing factors associated with a successful treatment response to cladribine. Data on relapse rates, MRI and EDSS scores over a period of up to five (MRI and EDSS) and six years (ARR), as well as adverse events and lymphocyte counts were collected retrospectively. Furthermore, baseline data characteristics were assessed in order to identify additional parameters that may influence the efficacy of cladribine treatment. Descriptive statistics were employed to illustrate the baseline data, efficacy and side effects associated with cladribine treatment. The results showed the following finding: First, treatment with cladribine was observed to result in a significant reduction in the annual relapse rate and MRI progression. Nevertheless, the EDSS scores exhibited minimal fluctuation, with a slight increase observed in several patients. Furthermore, apart from the typical adverse effects associated with cladribine, no severe adverse events were observed. Only two patients exhibited grade 4 lymphopenia, which did not result in any significant complications. With regard to the various prior treatments, dimethyl fumarate pre-treatment demonstrated the most pronounced influence on the risk of lymphopenia among all platform treatments. To evaluate the effects of prior treatments on the efficacy of cladribine treatment, Kaplan-Meier curves were utilized. This analysis revealed notable discrepancies in the efficacy trajectory between different pre-treatments. However, a subsequent Log-Rank test indicated that the pre-treatment did not exert a significant impact on the time to a first event (relapse, MRI progression, EDSS worsening). Finally, a Cox regression analysis was employed to ascertain the pivotal risk and protective factors influencing the efficacy of the cladribine treatment course. A low annual relapse rate at baseline was identified as a protective factor for early relapses, and a low MRI progression at baseline was identified as a protective factor for early MRI progression in the disease course. Furthermore, pre-treatment appeared to serve as a protective factor for the occurrence of early MRI activity. However, this finding may be attributed to the longer disease duration observed in this group, as well as the concomitant lower clinical activity. In conclusion, the choice of treatment depends on many variables and our study cannot fully identify a specific pattern among patients with a favourable response, but we can provide some guidance on the efficient use of cladribine in clinical routine.