BackgroundCladribine tablets 10mg (cumulative dose 3.5mg/kg [CT3.5] over 2 years) showed efficacy vs placebo in patients with relapsing-remitting multiple sclerosis in the CLARITY study. This post-hoc analysis investigated efficacy outcomes for patients with a history of disease-modifying therapy (DMT) use prior to entering CLARITY.MethodsCLARITY included patients previously treated with 0–2 DMTs (patients treated with >2 DMTs were excluded). Analysis of efficacy, annualised relapse rate (ARR), relapse-free rate, MRI activity, and time to 3-month and 6-month confirmed disability progression (CDP), were stratified by prior DMT therapy. P-Values ResultsPrior DMT patients were randomised to CT3.5 (n=110) and placebo (n=132). Treatment with CT3.5 vs placebo resulted in a nominally significant reduction in ARR (0.22 vs 0.42; PConclusionsPatients who received prior DMT treatment showed significant improvements in efficacy outcomes with CT3.5 compared to placebo. Findings therefore support a consistent effect of cladrib- ine tablets across a broad range of patients, including patients who have used other DMTs.CLARITY:NCT00213135dominic.jack@merckgroup.com