Predictors of Cladribine Effectiveness and Safety in Multiple Sclerosis: A Real-World, Multicenter, 2-Year Follow-Up Study

INTRODUCTION: Cladribine administration has been approved for the treatment of relapsing–remitting multiple sclerosis (MS) in 2017; thus, data on cladribine in a real-world setting are still emerging. METHODS: We report on cladribine effectiveness, safety profile, and treatment response predictors in 243 patients with MS followed at eight tertiary MS centers. Study outcomes were: (1) No Evidence of Disease Activity-3 (NEDA-3) status and its components (absence of clinical relapses, MRI activity, and sustained disability worsening); (2) development of grade III/IV lymphopenia. The relationship between baseline features and the selected outcomes was tested via multivariate logistic models. RESULTS: Of the 243 subjects included in the study (66.5% female, age 34.2 ± 10 years, disease duration 6.6 ± 9.6 years), 64% showed NEDA-3 at median follow-up (22 months). Patients with higher number of previous treatments had lower probability to retain NEDA-3 [odds ratio (OR) 0.64, 95% confidence interval (CI) 0.41–0.98, p = 0.04] and were more prone to experience clinical relapses (OR 1.6, 95% CI 1–2.6, p = 0.04). The presence of active lesions at baseline was associated with follow-up magnetic resonance imaging (MRI) activity (OR 1.92, 95% CI 1.04–3.55, p = 0.04). Patients with higher rate of relapses in the year prior to cladribine start were at higher risk of developing sustained disability worsening (OR 2.95% CI 1–4.2, p = 0.04). Lymphopenia grade III/IV over the follow-up was associated with baseline lymphocyte count (OR 0.998, 95% CI 0.997–0.999, p = 0.01). CONCLUSION: In this large cohort, we confirm previous data about cladribine effectiveness on disease activity and disability worsening and provide information on response predictors that might inform therapeutic choices.