Treatment continuation with cladribine at 5 years after initiation in people with multiple sclerosis: A case series and literature review

Background: Cladribine is an oral disease-modifying drug approved for the treatment of highly active relapsing multiple sclerosis (MS). The recommended number of treatment courses is two, with the courses given 1 year apart (i.e., in year 1 and year 2), followed by 2 years without treatment. Pivotal clinical trials showed that, compared with placebo, cladribine significantly reduced relapse rates, risk of disability progression and magnetic resonance imaging measures of disease activity for up to 4 years in treatment-na & iuml;ve or -experienced adults with relapsing-remitting MS (RRMS). The management of patients and requirement for retreatment with cladribine beyond year 4 is unclear. Methods: We describe the treatment history and outcomes of three people with MS retreated with cladribine, given as a third course 5 years after treatment initiation. We also include a review of evidence on retreatment with cladribine from year 3 onwards and a discussion of patient selection criteria for retreatment. Results: The cases included a 53-year-old female patient with RRMS, a 43-year-old female patient with RRMS, and a 42-year-old male patient with RRMS. Six months after the third course of cladribine, all three patients were relapse-free and stable on magnetic resonance imaging, with no evidence of disease activity. At 11-12 months follow-up, all patients had clinical and radiological stability (i.e., no evidence of disease activity). Conclusion: Continuation of oral cladribine treatment may be considered for people with MS beyond year 5 following completion of the initial two courses. Our real-world experience is ongoing and additional data are required to obtain insight into patient phenotypes which predict response to cladribine treatment.