Cladribine tablets reduce the risk of disability progression and relapse in patients with relapsing multiple sclerosis (MS), the CLARITY clinical trial indicates.
The treatment was also well-tolerated and had a good safety profile, according to a presentation at the Annual Meeting of the American Academy of Neurology (AAN) in Boston, April 22-28.
Cladribine is an oral small molecule developed by Merck developed that selectively targets immune lymphocytes. The white blood cells are believed to play a central role in mechanisms underlying MS.
The Phase 3 CLARITY trial (NCT00213135) investigated the safety and effectiveness of cladribine in 1,326 relapsing-remitting MS (RRMS) patients. The study’s primary measuring stick was the change in the annual rate of relapse (ARR) at 96 weeks. Researchers also wanted to see if the treatment could increase the number of relapse-free patients and could impact the progression of disability.
Cladribine significantly decreased the risk of disease progression and relapse in a subset of 289 patients with high disease activity, trial showed. The risk over six months decreased substantially in 82 percent of those patients, versus 47 percent in the CLARITY population overall, when compared with a placebo, researchers said.
The tablets also reduced the relative risk of ARR in 67 percent of patients with high disease activity, compared with 58 percent in the overall CLARITY population.
“We know that a proportion of patients with MS have a higher risk of relapse and disability progression than the broader population,” Gavin Giovannoni, the trial’s principal researcher, said in a press release. “These data are important since they indicate that patients in the high disease activity subgroup treated with Cladribine Tablets showed a greater response than that seen in the overall CLARITY trial population.”
The analysis included patients who had never received treatment or had been exposed to disease modifying drugs before the trial. Researchers also found that relapse, treatment history and brain scan characteristics can help identify patients who are at higher risk of experiencing relapses or disease progression.
Taking cladribine for 20 days over a two-year period initially led to a decrease in the number of patients’ white blood cells, the CLARITY and the CLARITY Extension study (NCT00641537) indicated. But by the end of treatment year 1 and 2, the numbers had recovered to within a normal range. Lymphopenia, or a drop in white blood cells, was the most common side effect reported in patients taking cladribine.
“Cladribine Tablets is thought to selectively target the adaptive immune response in MS, and may be able to address a medical need in those patients already at higher risk of disability progression or relapses,” Luciano Rossetti, Merck’s head of Global R&D, concluded.