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Completed

NCT Number: NCT06399718

A Study to Assess BOTOX Injections for the Change of Masseter Muscle Prominence in Adult Participants

The masseter muscle is one of the muscles in the lower face used for chewing. The prominence of the masseter muscle can appear as a widened lower face which some individuals deem as aesthetically undesirable and can be treated by selectively weakening the masseter muscles with small quantities of botulinum toxin. The purpose of this study is to assess how safe and effective injection of onabotulinumtoxinA (BOTOX) is in adult participants with Masseter Muscle Prominence (MMP).

BOTOX is being investigated for the treatment of Muscle Masseter Prominence. In Period 1, participants are placed in 1 of 2 groups, called treatment arms. Each group receives a different treatment, placebo or BOTOX. There is a 1 in 4 chance that participants will be assigned to placebo. In Period 2, eligible participants can receive an optional open-label retreatment of BOTOX. Approximately 200 adult participants with MMP will be enrolled in the study at approximately 20 sites in the United States.

Participants will receive intramuscular injections across both the right and left masseter muscle of either BOTOX or placebo on Day 1. Participants who are eligible for re-treatment will be given a BOTOX injection on either the Day 180, 210, 240, or 270 visit and will be followed up for up to 6 months.

There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular monthly visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, checking for side effects, and completing questionnaires.

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Key information

Conditions

Masseter Muscle Prominence

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Westside Aesthetics /ID# 248232, Los Angeles, California, United States

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participant meets the following criteria:
  • Bilateral Grade 4 or Grade 5 Masseter Muscle Prominence (MMP) (identical grades for left and right sides of the face), as determined by the investigator using the Masseter Muscle Prominence Scale (MMPS).
  • Bilateral Grade 4 or Grade 5 MMP (identical grades for left and right sides of the face), as determined by the participant using the Masseter Muscle Prominence Scale - Participant (MMPS-P).
  • Investigator and participant scoring of MMPS and MMPS-P must be the same.
  • Body mass index (BMI) ≤ 30 kg/m^2 using the calculation: BMI = weight (kg)/height (m)^2.

Exclusion criteria

  • Excess lower facial fat, jowling, loose or lax skin in lower face, or parotid gland prominence that could interfere with MMPS or MMPS-P grading.
  • Asymmetry of left and right sides of the face that could prevent identical MMPS or MMPS-P grading on both sides of the face.
  • History of or current temporomandibular disorder (TMJD), or presence of signs/symptoms of possible TMJD.

Treatment and study plan

Botox

Drug

Intramuscular Injections

Other names: OnabotulinumtoxinA

Placebo

Drug

Intramuscular Injections

Primary outcomes

  1. Composite Achievement of MMP Severity Improvement and at Least a 2-Grade Improvement from Baseline by Both Investigator-Rated MMPS and Participant-Rated MMPS-P

    Time frame: Day 90

    The investigator and participant each assessed the participant's Masseter Muscle Prominence (MMP) using the Masseter Muscle Prominence Scale (MMPS) and the Masseter Muscle Prominence Scale-Participant (MMPS-P), respectively. Both are a 5-point masseter muscle severity scale with grades ranging from 1 (minimal/not at all noticeable) to 5 (very marked/extremely noticeable).

  2. Number of Participants with Adverse Events (AEs)

    Time frame: Baseline to Day 360

    An AE is defined as any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product which does not necessarily have a causal relationship with this treatment.

Secondary outcomes

  1. Percentage of Participants who Responded as "Very satisfied" or "Satisfied" on the Lower Facial Shape Questionnaire - Treatment Satisfaction Assessment (LFSQ-TXSAT)

    Time frame: Day 90

    The LFSQ-TXSAT measures satisfaction with the effect of treatment using a 5-point scale ranging from 'Very satisfied' to 'Very dissatisfied.'

  2. Percentage of Participants who Responded as "Not at all bothered" or "A little bothered" on the Bother Impact Assessment for Masseter Muscle Prominence (BIA-MMP)

    Time frame: Day 90

    The BIA-MMP is a single item evaluation of how bothered the participant is by the appearance of their lower face using a 5-point scale from 'Not at all bothered' to 'Extremely bothered.'

  3. Change from Baseline in Lower Facial Shape Questionnaire-Impact Assessment (LFSQ-IA) Summary Score

    Time frame: Baseline to Day 90

    The LFSQ-IA measures psychosocial impact due to the appearance of the lower face. The LFSQ-IA summary score ranges from '0 (best)' to '24 (worst).'

  4. Percentage of Participants Achieving Investigator-Rated MMPS Improvement Over Time

    Time frame: Baseline to Day 360

    The investigator assessed the participant's MMP using the MMPS, a 5-point masseter muscle severity scale with grades ranging from 1 (minimal) to 5 (very marked).

  5. Percentage of Participants Achieving Participant-Rated MMPS-P Improvement Over Time

    Time frame: Baseline to Day 360

    The investigator assessed the participant's MMP using the MMPS-P, a 5-point masseter muscle severity scale with grades ranging from 1 (not at all noticeable) to 5 (extremely noticeable).

Sponsors and collaborators

Lead sponsor

AbbVie

Industry

Registry information

Official study title

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

Acronym: MMP US P3 417

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
May 6, 2024
Registry last updated
Nov 17, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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