A Controlled Phase 2b Trial to Assess the Efficacy and Safety of a Single Intervention of OnabotulinumtoxinA for Treating Masseter Muscle Prominence

Abstract

Background: Masseter muscle prominence (MMP) is a benign condition characterized by a wide, square, or trapezoidal lower facial shape, which may be considered undesirable. Objectives: To evaluate onabotulinumtoxinA (onabotA) efficacy and safety for MMP treatment. Methods: In a Phase 2b study, adults with investigator- and participant-assessed bilateral Grade 4/5 MMP on the 5-grade MMP Scale (MMPS) and MMPS—Participant, respectively, were randomized 1:1:1 to receive a single intramuscular injection of onabotA 48 U, 72 U, or placebo in the masseter muscles. The primary endpoint was the proportion of patients achieving investigator-assessed MMPS Grade ≤3 at Day 90. Adverse events were monitored throughout. Results: Patients received onabotA 48 U (n = 53), 72 U (n = 46), or placebo (n = 46). Significantly greater proportions achieved MMPS Grade ≤3 with onabotA vs placebo (90.6%, 91.3%, and 21.7% for onabotA 48 U, 72 U, and placebo, respectively, at Day 90; P