Articles Efficacy and Safety of IncobotulinumtoxinA in Subjects Previously Treated with Botulinum Toxin Versus Toxin-Naı̈ve Subjects with Cervical Dystonia

Background: To determine whether botulinum toxin treatment history affected the outcomes of a study comparing the safety and efficacy of incobotulinumtoxinA with placebo in subjects with cervical dystonia (CD). Methods: This was a prospective, double-blind, randomized, placebo-controlled, multicenter trial in botulinum toxin-treated or toxin-naı̈ve CD subjects. Subjects received a fixed dose of either 120 U or 240 U of incobotulinumtoxinA or placebo. The primary outcome measure was change from baseline to Week 4 in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score. Treatment-emergent adverse events (TEAEs) were also evaluated. This report represents a subgroup analysis of botulinum toxin-treated or toxin-naı̈ve subjects. Results: Participants (N5233; 38.6 % toxin-naı̈ve) had a mean age of 52.8 years. IncobotulinumtoxinA significantly improved TWSTRS total scores from baseline to Week 4 in both dose groups versus placebo, and the improvement persisted through the end of the study (#20 weeks). Both the previously toxin-treated and toxin-naı̈ve subjects demonstrated significant improvements in TWSTRS total scores at Week 4 compared to baseline. The most frequent TEAEs in the incobotulinumtoxinA groups were dysphagia, neck pain, and muscular weakness, which were generally mild. TEAEs were more common in the 240 U group and toxin-naı̈ve subjects. Discussion: Overall, incobotulinumtoxinA was safe and effective in CD, regardless of toxin therapy history. A lower starting dose may be better tolerated amon