The ASPEN-1 Phase 3 randomized controlled trial evaluated the efficacy and safety of DaxibotulinumtoxinA for Injection (DAXI) in treating cervical dystonia (CD). The study included adults with moderate-to-severe CD (Toronto Western Spasmodic Torticollis Rating Scale [TWSTRS] total score ≥20) across 60 sites in 9 countries. Participants were randomized to receive either DAXI 125U, DAXI 250U, or placebo and were followed for up to 36 weeks. The primary endpoint was the change from baseline in TWSTRS total score averaged across weeks 4 and 6. Key secondary endpoints included duration of effect, Clinical and Patient Global Impression of Change (CGIC, PGIC), TWSTRS subscale scores, and safety. Results showed that both DAXI 125U and 250U significantly improved the TWSTRS total score compared to placebo (DAXI 125U: −8.5 [1.93], p < 0.0001; DAXI 250U: −6.6 [1.92], p = 0.0006). The median duration of effect was 24.0 weeks with DAXI 125U and 20.3 weeks with DAXI 250U. Significant improvements were also observed in CGIC and PGIC responder rates and TWSTRS subscales. Treatment-related adverse events (TEAEs) were reported by 29.6% of participants with DAXI 125U, 23.8% with DAXI 250U, and 17.4% with placebo, with injection site pain being the most common. The study concluded that DAXI, at doses of 125U and 250U, is an effective, safe, long-acting, and well-tolerated treatment for CD.The ASPEN-1 Phase 3 randomized controlled trial evaluated the efficacy and safety of DaxibotulinumtoxinA for Injection (DAXI) in treating cervical dystonia (CD). The study included adults with moderate-to-severe CD (Toronto Western Spasmodic Torticollis Rating Scale [TWSTRS] total score ≥20) across 60 sites in 9 countries. Participants were randomized to receive either DAXI 125U, DAXI 250U, or placebo and were followed for up to 36 weeks. The primary endpoint was the change from baseline in TWSTRS total score averaged across weeks 4 and 6. Key secondary endpoints included duration of effect, Clinical and Patient Global Impression of Change (CGIC, PGIC), TWSTRS subscale scores, and safety. Results showed that both DAXI 125U and 250U significantly improved the TWSTRS total score compared to placebo (DAXI 125U: −8.5 [1.93], p < 0.0001; DAXI 250U: −6.6 [1.92], p = 0.0006). The median duration of effect was 24.0 weeks with DAXI 125U and 20.3 weeks with DAXI 250U. Significant improvements were also observed in CGIC and PGIC responder rates and TWSTRS subscales. Treatment-related adverse events (TEAEs) were reported by 29.6% of participants with DAXI 125U, 23.8% with DAXI 250U, and 17.4% with placebo, with injection site pain being the most common. The study concluded that DAXI, at doses of 125U and 250U, is an effective, safe, long-acting, and well-tolerated treatment for CD.