Side effects that occurred early in people with multiple sclerosis during the first year of treatment with cladribine tablets: a plain language summary.

People with multiple sclerosis (also shortened to MS) may have difficulties staying on treatment due to side effects. Cladribine tablets, approved for treating relapsing forms of MS, are given by mouth for four short periods over two years. The benefit of convenient dosing may be lost if side effects prevent people with MS from finishing their treatment. This is the summary of a study that examined side effects from cladribine tablets treatment in the first 12 weeks of two clinical studies called CLARITY and ORACLE-MS. Overall, 34.7% of participants who took cladribine tablets experienced drug-related side effects compared to 23.2% of participants who took placebo. Most side effects were mild and were seen in 54.8% of participants taking cladribine tablets and 59.1% taking the placebo. A low number of participants discontinued treatment due to side effects (1.6% of participants who took cladribine tablets; 1.4% of participants who took placebo). The researchers concluded that cladribine tablets are well-tolerated and people with MS are likely to complete the full treatment course. ClinicalTrials.gov NCT numbers: CLARITY study - NCT00213135 and ORACLE-MS study - NCT00725985.