Discussion
This phase 3, randomized, double-blind study demonstrated that a single injection of aboBoNT-A 50 U was superior to matching placebo in improving the appearance of glabellar lines at maximum frown at day 29 (95% compared with 1%; per ILA), and non-inferior to active comparator (onaBoNT-A 20 U; per ILA) in Chinese adults. Efficacy and responder rates in this population were similar to those in a study conducted in 2010 assessing botulinum toxin to treat glabellar lines in Chinese patients [The proportion of patients who had severe glabellar lines at baseline (56.9%) in the current study was similar with previous studies investigating aboBoNT-A 50 U in glabellar lines enrolling mainly Caucasian patients: 48.6%, 62.4%, and 56.2% in studies by Ascher et al. (2018), Monheit et al. (2007), and Rzany et al. (2006; five injection sites treatment arm), respectively [In the current study, patients also reported statistically significant improvements in the perception of their age (i.e., they perceived that they looked younger) after treatment with aboBoNT-A compared with placebo during cycle 1, and after multiple cycles of treatment. This is supported by Chang et al. (2016), whereby patients reported that they believed they looked an average of 5.6 years younger after aboBoNT-A treatment [Patients and investigator assessments were concordant in this study. Patients reported that response to treatment occurred after a median of 2.0 days post-aboBoNT-A treatment during cycle 1, with 33% of patients responding to treatment at day 1. These results are supported by other studies showing rapid onset of response, with studies by Moy et al. (2009) and Brandt et al. (2009) reporting the median time to onset of effect as early as 3 days after treatment with aboBoNT-A, and Monheit et al. (2020) at day 2 [The agreement between responder rates measured by ILA and IRA of photographs was generally limited, which may suggest that photographs are less suitable than live assessment to assess the effect of aboBoNT-A on the appearance of dynamic glabellar lines. The disparity between the proportion of male and female participants enrolled in the study may also be considered a limitation; however, this is a known difficulty in aesthetic studies. The results from cycle 5 must also be interpreted with caution, as the study design meant that a relatively small number of patients required five treatment cycles within the planned follow-up period of 15 months.Single and repeated injections with aboBoNT-A administered over a maximum of 15 months were well-tolerated and similar to that seen in other patient populations and ethnicities [