Cladribine in the treatment of multiple sclerosis

Karen Schreiber, Per Soelberg Sorensen

Treatment with cladribine leads to a preferential and sustained reduction in lymphocytes and monocytes, resulting in long-lasting depletion of CD4+ and CD8+ T cells. In the Phase III placebo-controlled trial in relapsing–remitting multiple sclerosis (the CLARITY study), oral cladribine at 96 weeks significantly reduced annual relapse rates by 54–57% compared with placebo. The risk of disability progression and brain lesion counts on MRI were also decreased. The therapy was well tolerated. The dosing regimen is convenient, but careful surveillance is still needed to detect unforeseen side effects. Until long-term safety data are available, the use of oral cladribine would primarily be as an escalating therapy in patients with breakthrough disease on IFN-b and glatiramer acetate.