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Merck KGaA and its Merck Serono division announced today that the clarity1 phase III pivotal trial of its proprietary oral formulation of cladribine (cladribine tablets) met the two-year primary endpoint of clinical relapse rate reduction in patients with relapsing-remitting multiple sclerosis (MS).
The two cladribine tablet treatment groups of the study, assessing different dose regimens, demonstrated a statistically significant reduction in the annualised rate of relapses compared to placebo. Patients from the lower total dose group experienced a 58% relative reduction in annualised relapse rates with respect to placebo.
Patients from the higher total dose group experienced a 55% relative reduction in annualised relapse rates with respect to placebo.
Overall, the frequencies of adverse events were low in the cladribine tablet treatment groups and were comparable to that observed in the placebo group. Lymphopenia, an expected event based on the presumed mechanism of action of cladribine, occurred more frequently in the cladribine tablet treatment groups. With the exception of lymphopenia, the most frequently reported adverse events in the three study groups were headaches and nasopharyngitis.
“We believe the clarity data mark an important milestone in the assessment of investigational oral treatments for multiple sclerosis and that cladribine tablets have the potential to make a real difference in the lives of patients,” said Elmar Schnee, executive board member with responsibility for the Pharmaceuticals business sector.
“Based on the successful completion of the clarity study, we plan to submit cladribine tablets for registration to the EMEA and to the FDA for mid-2009.”
Secondary endpoints of the clarity study were also met, including reduction of lesion activity as measured by magnetic resonance imaging (MRI), proportion of subjects relapse-free and disability progression. Full study results will be submitted for
presentation at an upcoming scientific meeting.
The clarity study was a two-year (96 weeks), randomised, double-blind, placebo-controlled, international trial. It enrolled 1,326 patients with relapsing-remitting MS according to the revised McDonald criteria.
Study participants were randomised to one of three different treatment groups consisting of two different dose regimens of cladribine tablets or matching placebo tablets. Cladribine tablets were given in two or four treatment courses in the first year, with each course consisting of once daily administration for four to five consecutive days, which means study patients took cladribine tablets for only 8 to 20 days during the year.
In the second year, two treatment courses were administered to all patient groups. The primary endpoint of the clarity study was the qualifying relapse rate at 96 weeks. Secondary endpoints included MRI endpoints, proportion of subjects relapse-free and disability progression at 96 weeks. Out of the 1,326 randomised patients, 90% of patients treated with cladribine tablets completed the study (92% in the lower total dose group and 89% in the higher total dose group) compared to 87% in the placebo group.