BOTOX® (Botulinum toxin type A) for the Reduction of Masseter Muscle Prominence: A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study

The primary objective of this study is to evaluate the **efficacy** and **safety** of BOTOX (Botulinum toxin type A) compared to placebo in the treatment of individuals with **masseter muscle prominence** (MMP). This is clinically relevant as MMP can lead to aesthetic concerns and functional issues, and effective treatment options are needed to address these challenges. The study aims to provide evidence on the therapeutic benefits and potential risks associated with BOTOX injections for this condition.

The clinical trial investigating the efficacy and safety of **BOTOX** compared to placebo for the treatment of **masseter muscle prominence** (MMP) involves a total of 49 participants. The study population includes both male and female subjects, with an age range that encompasses categories 3 and 4, indicating a broad spectrum of adult participants. The trial population was selected to include individuals with bilateral MMP, as determined by both the investigator and the subjects themselves, ensuring bilateral symmetry at the start of the trial. Participants were required to have a body mass index calculated using the standard formula, rounded to the nearest whole number. The study also considers vulnerable populations, although specific lifestyle factors such as diet, physical activity, or habits are not detailed in the available data. The inclusion of both genders and the consideration of vulnerable groups highlight the trial's comprehensive approach to assessing the treatment's impact across a diverse demographic. The sponsor did not provide additional information regarding specific lifestyle considerations or further demographic details.

The clinical trial is designed as a **randomized**, **double-blind**, **placebo-controlled** study to evaluate the efficacy and safety of **BOTOX** (botulinum toxin type A) in reducing **masseter muscle prominence**. The trial will involve adult participants and is structured to ensure rigorous scientific assessment through its methodology. Participants will be randomly assigned to receive either the active treatment or a placebo, with both the participants and investigators blinded to the treatment allocation to minimize bias. The trial is expected to span approximately two years, with an estimated end date in late 2025.

The sequence of study visits begins with an inclusion (screening) visit, where eligibility is assessed based on criteria such as body mass index and bilateral masseter muscle prominence. Following successful screening, participants will attend a baseline visit (Day 1) where initial assessments are conducted. Subsequent follow-up visits will occur at regular intervals, with a primary endpoint assessment at Day 90. The primary endpoints include achieving a ≥2-grade improvement in masseter muscle prominence from baseline, as assessed by both the investigator and the participant. Secondary endpoints will evaluate changes in lower facial volume and width, as well as responses on specific questionnaires designed to assess facial shape and treatment satisfaction.

The expected length of participant involvement is up to 12 months, with the possibility of early termination if specific conditions arise, such as adverse events or withdrawal of consent. Participants will conclude their involvement with an end-of-study visit, where final assessments are conducted to ensure participant safety and collect comprehensive data for analysis. The trial's design and procedures are meticulously crafted to uphold the highest standards of clinical research, ensuring the reliability and validity of the findings.

The clinical trial involves the administration of **BOTOX 100 Allergan Units Powder for Solution for Injection**, which contains the active substance **botulinum toxin type A**. This experimental medication is provided in the form of a powder that is reconstituted into a solution for injection. The route of administration is via **intramuscular injection**. The maximum daily dose is 48 IU (international units), with a total maximum dose of 48 IU over the treatment period. The treatment duration is set for a maximum of 12 weeks. The BOTOX is packaged in a masked/blinded manner to resemble the placebo packaging, ensuring the double-blind nature of the study. Participant compliance with the dosing schedule is monitored throughout the trial.

The study also includes a **placebo** treatment, which is a solution for injection designed to mimic the appearance of the BOTOX solution. The placebo is used as a comparator to evaluate the efficacy and safety of the BOTOX treatment in subjects with masseter muscle prominence. The placebo does not contain any active substance and is administered in the same manner as the experimental medication to maintain the study's double-blind design. The placebo administration follows the same dosing schedule and monitoring procedures as the BOTOX treatment to ensure consistency and reliability of the trial results.

The efficacy of BOTOX® (Botulinum toxin type A) in the treatment of **masseter muscle prominence (MMP)** will be assessed through a series of primary and secondary endpoints. The primary endpoints include the achievement of a Masseter Muscle Prominence Score (MMPS) of at least a 2-grade improvement from baseline at Day 90, as assessed by both the investigator and the subject. Secondary endpoints will evaluate responses on the Lower Facial Shape Questionnaire - Treatment Satisfaction (LFSQ-TXSAT) follow-up version and the BIA-MMP at Day 90. Additionally, changes from baseline in lower facial volume and width, calculated from standardized images, will be measured. The change in the Lower Facial Shape Questionnaire - Impact Assessment (LFSQ-IA) summary score at Day 90 will also be assessed.

These efficacy parameters will be collected and analyzed at specific timepoints, with Day 90 being a critical assessment day. The tools and instruments involved in these assessments include standardized imaging techniques for measuring facial volume and width, as well as validated questionnaires for evaluating patient-reported outcomes. The study is designed as a Phase 3, multicenter, randomized, double-blind, placebo-controlled trial, ensuring rigorous evaluation of the treatment's efficacy compared to placebo.