Efficacy, safety, and pharmacokinetics of natalizumab in Japanese multiple sclerosis patients: A double-blind, randomized controlled trial and open-label pharmacokinetic study

Background Natalizumab, an anti-α4 integrin monoclonal antibody, has demonstrated efficacy in phase 2 and 3 studies of predominantly Caucasian patients with relapsing-remitting multiple sclerosis (RRMS). Objective To evaluate the efficacy, safety, pharmacokinetics (PK), and pharmacodynamics (PD) of natalizumab in Japanese RRMS patients. Methods This multicenter, phase 2 study included an open-label PK/PD study in 12 patients (part A) and a double-blind, placebo-controlled, randomized (computer-generated sequence) study in 94 patients (part B). For part B, patients received intravenous natalizumab 300 mg (n=47) or placebo (n=47) every 4 weeks. The primary efficacy endpoint was the rate of development of new active lesions (gadolinium-enhancing or new/enlarging T2 lesions) over 24 weeks. Clinical relapses and safety were also assessed. Results New active lesions developed at a significantly lower mean rate in natalizumab-treated patients (0.06 lesions/24 weeks) than in placebo-treated patients (0.35 lesions/24 weeks) (p<0.001). The annualized relapse rate was 0.53 for natalizumab and 1.73 for placebo (p<0.001). Twice as many natalizumab-treated patients (79%) as placebo-treated patients (38%) were relapse-free (p<0.001). The safety, PK, and PD profiles of natalizumab in this study were consistent with data in Caucasian RRMS patients. Conclusions In Japanese RRMS patients, natalizumab treatment every 4 weeks for 24 weeks was well tolerated and reduced the development of new brain lesions and relapses (Funded by Biogen; ClinicalTrials.gov identifier: NCT01440101).