The ASPEN-1 phase 3 trial evaluated the efficacy and safety of DaxibotulinumtoxinA (DAXI) in patients with cervical dystonia (CD). The study enrolled 301 participants across 60 sites in Europe and North America, randomized to receive DAXI 125U, DAXI 250U, or placebo. The primary endpoint was the change in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score from baseline, averaged across weeks 4 and 6. DAXI 125U and 250U significantly improved the TWSTRS score compared to placebo, with mean differences of -8.5 and -6.6, respectively. The median duration of effect was 24.0 weeks for DAXI 125U and 20.3 weeks for DAXI 250U. Both doses showed significant improvements in Clinical and Patient Global Impression of Change (CGIC and PGIC) responder rates and TWSTRS subscale scores. Treatment-emergent adverse events (TEAEs) were reported by 29.6%, 23.8%, and 17.4% of participants in the DAXI 125U, DAXI 250U, and placebo groups, respectively. The most common TEAEs were injection site pain, musculoskeletal pain, and dysphagia. DAXI was found to be effective, safe, and well-tolerated for CD, with a longer duration of effect compared to existing treatments. The study supports DAXI as a long-acting, well-tolerated treatment option for CD.The ASPEN-1 phase 3 trial evaluated the efficacy and safety of DaxibotulinumtoxinA (DAXI) in patients with cervical dystonia (CD). The study enrolled 301 participants across 60 sites in Europe and North America, randomized to receive DAXI 125U, DAXI 250U, or placebo. The primary endpoint was the change in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score from baseline, averaged across weeks 4 and 6. DAXI 125U and 250U significantly improved the TWSTRS score compared to placebo, with mean differences of -8.5 and -6.6, respectively. The median duration of effect was 24.0 weeks for DAXI 125U and 20.3 weeks for DAXI 250U. Both doses showed significant improvements in Clinical and Patient Global Impression of Change (CGIC and PGIC) responder rates and TWSTRS subscale scores. Treatment-emergent adverse events (TEAEs) were reported by 29.6%, 23.8%, and 17.4% of participants in the DAXI 125U, DAXI 250U, and placebo groups, respectively. The most common TEAEs were injection site pain, musculoskeletal pain, and dysphagia. DAXI was found to be effective, safe, and well-tolerated for CD, with a longer duration of effect compared to existing treatments. The study supports DAXI as a long-acting, well-tolerated treatment option for CD.