Efficacy and Safety of IncobotulinumtoxinA in Asian Subjects: A Pooled Analysis of Clinical Trials in the Treatment of Glabellar Frown Lines

September 2016 | Volume 15 | Issue 9 | Original Article | 1084 | Copyright © September 2016

Kyle Seo MD PhD,a,b Tsen-Fang Tsai MD,c Yates Yen-Yu Chao MD,d Greg J. Goodman FACDe,f

aModelo Clinic, Seoul, Korea
bDepartment of Dermatology, Seoul National University College of Medicine, Seoul, Korea
cDepartment of Dermatology, National Taiwan University Hospital, Taipei, Taiwan
dL1 Cosmetic Surgery and Laser Center, Taipei, Taiwan
eDepartment of General Practice, Monash University, Clayton, Victoria, Australia
fSkin and Cancer Foundation, Carlton, Victoria, Australia

BACKGROUND: Owing to differences in facial anatomy and cultural beauty ideals, dose adaptations are often necessary when administering botulinum toxin type A to Asians and non-Asians. Objective: To assess potential differences in the efficacy and safety of incobotulinumtoxinA in Asian and non-Asians.
METHODS: Efficacy data were pooled from several Phase II/III trials that used 20 U incobotulinumtoxinA to treat glabellar frown lines in Asian subjects. The variable of interest was investigator-assessed improvement in scores on the 4-point Facial Wrinkle Scale from baseline to days 30, 60, 90, and 120. Subjects with a 1-point improvement were considered ‘responders’. Data were also assessed for treatment-emergent adverse events, treatment-emergent serious adverse events, and adverse events of special interest among a pool of incobotulinumtoxinA safety studies.
RESULTS: Four trials were pooled, comprising 19 Asian and 563 non-Asian subjects. At maximum frown on day 30, 100% of Asians and 87% of non-Asians were responders; by day 120, values were 37% and 40%, respectively. At rest on day 30, 63% of Asians and 56% of non-Asians were responders. Corresponding values for day 120 were 11% and 25%. The mean change in score on the Facial Wrinkle Scale from baseline over time was similar in both groups. Very few adverse events occurred. Overall, treatment-emergent adverse events were lower amongst Asians than non-Asians.
CONCLUSIONS: Compared with non-Asians, a trend towards slightly higher responses was observed in Asians at maximum frown. There were no clinically relevant differences in the safety of incobotulinumtoxinA when administered to Asian and non-Asian subjects.

J Drugs Dermatol. 2016;15(9):1084-1087.


Botulinum toxin type A (BoNT/A) formulations are used in aesthetics for the treatment of facial wrinkles.1,2 IncobotulinumtoxinA (Xeomin®/Xeomeen®/Bocouture®/XEOMIN Cosmetic, NT 201; free from complexing proteins, Merz Pharmaceuticals GmbH, Germany) is indicated for the treatment of glabellar frown lines worldwide and crow’s feet in European markets,3 where it has proven efficacy and safety.4,5 Particular facial muscles are activated during the expression of certain emotions; the glabellar region and, in particular, the corrugator muscles play an important role in communication through the facial expression of anger, fear and sadness.6-8 Moreover, botulinum toxin may be of use as a treatment for major depressive disorder.9
The demand for aesthetic procedures, including the use of BoNT/A, is increasing in Asia.10 Owing to differences in facial anatomy and standards of perceived beauty between Asian and Caucasian populations, there are different requirements for aesthetic procedures and it is often necessary to adapt the doses of BoNT/A used.11,12 Such facial anatomic variations include differences in the size and mass of the corrugator muscles and a typically thinner and shorter supercilii muscle among Asians in comparison with Caucasians.13 Despite these differences in aesthetic requirements, there is a paucity of guidelines specific to the use of aesthetic procedures in Asians, although recommendations on the use of BoNT/A are available for Korean physicians.11
In order to assess whether differences exist between Asians and non-Asians in terms of their response to incobotulinumtoxinA treatment in the clinical trial setting, this study analyzed pooled efficacy and safety data from several Phase II/III studies that used incobotulinumtoxinA at the standard dose of 20 U for the treatment of glabellar frown lines in Asian subjects from Japan, Korea, Taiwan, China, and Hong Kong.