An update on cladribine for relapsing-remitting multiple sclerosis.

INTRODUCTION: Despite recent progress, currently available therapies for relapsing remitting multiple sclerosis (MS) are only partly effective, and their use is limited by tolerability and safety issues, as well as high cost. Cladribine was originally rejected by the regulatory authorities in both the European Union and USA in 2011, but in June 2017 the European Medical Agency recommended marketing authorization for treatment of aggressive relapsing MS. Areas covered: We provide an update on chemistry, mechanism of action, efficacy and safety of cladribine for the treatment of MS. Expert opinion: Cladribine is well tolerated, it is dosed orally in cycles of one year, the need for regular blood testing during treatment is likely limited, and the two-year efficacy data for treatment of relapsing MS are at least in the same range as the most efficient licensed treatments. The increased risk of malignancies reported in the pivotal trial seems to be caused by unexpectedly low numbers of malignancies in the placebo group. Cladribine could therefore be an alternative for many patients with relapsing remitting MS. The main caveat is the lack of long term efficacy and safety data. Currently there are insufficient data to guide further treatment of patients who have completed two treatment cycles of cladribine.