Efficacy and Safety of IncobotulinumtoxinA in the Treatment of Lower Limb Spasticity in Japanese Subjects

OBJECTIVE: To confirm the efficacy and safety of incobotulinumtoxinA (Xeomin®, Merz Pharmaceuticals GmbH; total dose 400 U) in Japanese subjects with lower limb (LL) poststroke spasticity using the Modified Ashworth Scale spasticity score for the plantar flexors (MAS-PF). METHODS: This phase III study (Japic clinical study database No. CTI-153030, 7 October 2015) included a double-blind, 12-week main period (MP) in which 208 subjects were randomized to receive one injection cycle of incobotulinumtoxinA 400 U (n = 104) or placebo (n = 104) in the pes equinus muscles, and an open-label extension (OLEX) that enrolled 202 subjects who received three injection cycles, 10–14 weeks in duration (the last cycle was fixed at 12 weeks). Changes in MAS-PF for incobotulinumtoxinA vs. placebo from baseline to Week 4 of the MP and to the end-of-cycle visits in the OLEX were evaluated. RESULTS: The area under the curve for the change in MAS-PF was statistically significantly greater with incobotulinumtoxinA vs. placebo in the MP (mean: −7.74 vs. −4.76; least squares mean: −8.40 vs. −5.81 [p = 0.0041]). In the OLEX, mean changes in MAS-PF from baseline to end-of-study showed continued improvement with repeated injections. No new safety concerns were observed with the incobotulinumtoxinA treatment. Its efficacy and safety were consistent regardless of the length of the injection cycle interval in the OLEX. CONCLUSION: This study demonstrated that incobotulinumtoxinA (total dose 400 U) is an effective and a well-tolerated treatment for LL spasticity in Japanese subjects using flexible injection intervals of 10–14 weeks.