Safety and efficacy of cladribine in multiple sclerosis: a systematic review and meta-analysis

Background: Previously, several studies investigated the effect of cladribine among patients with multiple sclerosis (MS) as a treatment option. Due to the contradictory results of previous studies regarding the efficacy and safety of cladribine in the MS population, we aimed to conduct a systematic review and meta-analysis by including clinical trials and observational studies in terms of having more confirmative results to make a general decision.

Methods: The three databases including PubMed, Scopus, and Web of Science were comprehensively searched in May 2022. We included the studies that investigated the efficacy and safety of cladribine in patients with MS. Eligible studies have to provide sufficient details on MS diagnosis and appropriate follow-up duration. We investigated the efficacy of cladribine with several outcomes including Expanded Disability Status Scale (EDSS) change, progression-free survival (PFS), relapse-free survival (RFS), and MRI-free activity survival (MFAS).

Results: After two-step reviewing, 23 studies were included in our qualitative and quantitative synthesis. The pooled SMD for EDSS before and after treatment was - 0.54 (95%CI: - 1.46, 0.39). Our analysis showed that the PFS after cladribine use is 79% (95%CI 71%, 86%). Also, 58% of patients with MS who received cladribine remained relapse-free (95%CI 31%, 83%). Furthermore, the MFAS after treatment was 60% (95%CI 36%, 81%). Our analysis showed that infection is the most common adverse event after cladribine treatment with a pooled prevalence of 10% (95%CI 4%, 18%). Moreover, the pooled prevalence of infusion-related adverse events was 9% (95%CI 4%, 15%). Also, the malignancies after cladribine were present in 0.4% of patients (95%CI 0.25%, 0.75%).

Conclusion: Our results showed acceptable safety and efficacy for cladribine for the treatment of MS except in terms of reducing EDSS. Combination of our findings with the results of previous studies which compared cladribine to other disease-modifying therapies (DMTs), cladribine seems to be a safe and effective drug in achieving better treatment for relapsing-remitting MS (RRMS) patients.