Efficacy and safety of DaxibotulinumtoxinA for injection in adults with cervical dystonia: Pooled global analysis of ASPEN-1 and ASPEN-1-CN randomized trials

BACKGROUND: DaxibotulinumtoxinA for injection (DAXI), the first long-acting botulinum toxin (BoNT) type A, is FDA approved for cervical dystonia (CD). DAXI's novel formulation, which includes a custom-engineered peptide, is designed to provide an extended duration of clinical benefit. OBJECTIVE: To evaluate the pooled efficacy and safety of DAXI for CD across two phase 3, multicenter, randomized, double-blind, placebo-controlled trials: ASPEN-1, conducted in North America and Europe, and ASPEN-1-CN, a similarly designed, smaller pivotal clinical trial, conducted in China. METHODS: Adults with moderate-to-severe CD were randomized (3:3:1) to receive DAXI 125U, DAXI 250U, or placebo. The primary endpoint was change from baseline in Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score averaged across weeks 4 and 6. A key secondary endpoint was duration, defined as time until loss of >80 % of peak effect. RESULTS: In all, 357 subjects were randomized and received DAXI 125U (n = 149), DAXI 250U (n = 154), or placebo (n = 54). DAXI 125U (-12.0) and DAXI 250U (-11.9) significantly improved the mean TWSTRS total score versus placebo (-4.6; P < 0.0001). Median (95 % CI) duration of effect was 24.1 (20.6-28.9) weeks for DAXI 125U and 22.0 (20.1-24.3) weeks for DAXI 250U. Rates of treatment-related dysphagia (125U: 4.7 %, 250U: 4.5 %) and muscle weakness (125U: 5.4 %, 250U: 4.5 %) were low for both active doses. CONCLUSIONS: This pooled analysis of two phase 3 trials demonstrates that DAXI is an effective, safe, and long-acting treatment for CD. Key adverse events occurred at rates lower than prior pivotal trials of BoNTs for CD.