Patients with multiple sclerosis treated with cladribine tablets for 2 years followed by placebo for an additional 2 years experience similar clinical benefits and lower risk for clinical worsening compared with patients treated with cladribine only for all 4 years, according to findings of an extension study published in Multiple Sclerosis Journal.
In this extension study of the CLARITY trial, a total of 806 patients with normal lymphocyte counts were provided a new treatment regimen. Participants who received placebo in the CLARITY trial now received 3.5 mg/kg cladribine tablets, whereas those who previously received cladribine were randomly assigned to either 3.5 mg/kg cladribine tablets or placebo.
Patients receiving cladribine tablets had higher lymphopenia grade ≥3 rates than the placebo group; however, overall adverse events were similar between groups.
More than 90% of patients treated with 3.5 mg/kg cladribine and approximately 100% of those in the placebo group recovered to grade 0 to 1 by the end of the extension study.
Investigators found that patients who had previously taken cladribine in the CLARITY trial for 2 years maintained clinical efficacy improvements during 2-year treatment with placebo in the extension. Additionally, approximately 75% of those receiving placebo in the extension study who had received 3.5 mg/kg cladribine in the preceding trial were free from relapse at study end.
According to the researchers, this extension study failed to power for efficacy analyses. The investigators also note that there was a variable gap between the CLARITY and extension study, which may further limit the findings.
Despite these limitations, this study demonstrates that the “short-duration posology and favorable risk-benefit profile of cladribine tablets treatment may facilitate treatment adherence, a significant challenge for patients with MS.”
Giovannoni G, Soelberg Sorensen P, Cook S, et al. Safety and efficacy of cladribine tablets in patients with relapsing-remitting multiple sclerosis: Results from the randomized extension trial of the CLARITY study [published online August 1, 2017]. Mult Scler. doi:10.1177/1352458517727603