A Study to Assess BOTOX Injections for the Change of Masseter Muscle Prominence in Adult Participants (MMP US P3 417)

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

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.

Study Overview

• Status: Completed
• Conditions: Masseter Muscle Prominence
• Intervention / Treatment: Drug: BOTOX; Drug: Placebo

• Study Type: Interventional
• Enrollment (Actual): 207
• Phase: Phase 3

Contacts and Locations

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90025-1708
      • Westside Aesthetics /ID# 248232
    • Newport Beach, California, United States, 92663
      • Private Practice - Dr. Steven G. Yoelin /ID# 268046
    • Vista, California, United States, 92083-6030
      • Pacific Clinical Innovations /ID# 248231
  • District of Columbia
    • Washington D.C., District of Columbia, United States, 20005-5002
      • Sherber + RAD /ID# 248894
  • Florida
    • Boca Raton, Florida, United States, 33431-6465
      • Steven Fagien MD Aesthetic Eyelid Plastic Surgery /ID# 248478
    • Coral Gables, Florida, United States, 33146-1837
      • Skin Research Institute LLC /ID# 248230
  • Georgia
    • Atlanta, Georgia, United States, 30328
      • Kavali Plastic Surgery and Skin Renewal Center /ID# 248480
  • Illinois
    • Chicago, Illinois, United States, 60610
      • DeNova Research /ID# 248237
  • Louisiana
    • Baton Rouge, Louisiana, United States, 70809
      • DelRicht Research /ID# 250313
    • New Orleans, Louisiana, United States, 70130-4353
      • Etre Cosmetic Dermatology and Laser Center /ID# 248229
  • Maryland
    • Baltimore, Maryland, United States, 21208-6391
      • Aesthetic Center at Woodholme /ID# 248481
  • Michigan
    • Clinton Township, Michigan, United States, 48038
      • Michigan Center for Research Corporation /ID# 249145
  • Nebraska
    • Omaha, Nebraska, United States, 68144
      • Skin Specialists /ID# 248233
  • New York
    • New York, New York, United States, 10016-4974
      • Laser & Skin Surgery Center of New York /ID# 248479
    • New York, New York, United States, 10021
      • Luxurgery /ID# 248236
  • Tennessee
    • Nashville, Tennessee, United States, 37203
      • The Practice of Brian S. Biesman MD PLLC /ID# 248226
    • Nashville, Tennessee, United States, 37205-2205
      • Sherman Aesthetic Center /ID# 248482
  • Texas
    • Austin, Texas, United States, 78746-4720
      • Westlake Dermatology & Cosmetic Surgery - Westlake /ID# 249875
    • Austin, Texas, United States, 78759
      • DermResearch Inc. /ID# 248227
    • Houston, Texas, United States, 77056-4129
      • Austin Institute for Clinical Research at SBA Dermatology /ID# 248228

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Double-Blind Period: BOTOX; Participants will receive BOTOX injections across both the right and left masseter muscle on Day 1.	Drug: BOTOX; Intramuscular Injections; Other Names: OnabotulinumtoxinA
Placebo Comparator: Double-Blind Period: Placebo; Participants will receive placebo injections across both the right and left masseter muscle on Day 1.	Drug: Placebo; Intramuscular Injections
Experimental: Open-Label Period: BOTOX; Participants who are eligible for re-treatment will receive BOTOX injections on either the Day 180, 210, 240, or 270 visit and will be followed for up to 6 months.	Drug: BOTOX; Intramuscular Injections; Other Names: OnabotulinumtoxinA

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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	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).	Day 90
Number of Participants with Adverse Events (AEs)	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.	Baseline to Day 360

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants Achieving Investigator-Rated MMPS Improvement Over Time	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).	Baseline to Day 360
Percentage of Participants Achieving Participant-Rated MMPS-P Improvement Over Time	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).	Baseline to Day 360
Percentage of Participants who Responded as "Very satisfied" or "Satisfied" on the Lower Facial Shape Questionnaire - Treatment Satisfaction Assessment (LFSQ-TXSAT)	The LFSQ-TXSAT measures satisfaction with the effect of treatment using a 5-point scale ranging from 'Very satisfied' to 'Very dissatisfied.'	Day 90
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)	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.'	Day 90
Change from Baseline in Lower Facial Shape Questionnaire-Impact Assessment (LFSQ-IA) Summary Score	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).'	Baseline to Day 90

Collaborators and Investigators

• Sponsor: AbbVie
• Investigators: Study Director: ABBVIE INC., AbbVie

Publications and helpful links

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): April 30, 2024
• Primary Completion (Actual): November 10, 2025
• Study Completion (Actual): November 10, 2025

Study Registration Dates

• First Submitted: May 1, 2024
• First Submitted That Met QC Criteria: May 1, 2024
• First Posted (Actual): May 6, 2024

Study Record Updates

• Last Update Posted (Actual): November 17, 2025
• Last Update Submitted That Met QC Criteria: November 14, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: OnabotulinumtoxinA; BOTOX; Masseter Muscle Prominence
• Additional Relevant MeSH Terms: Amino Acids, Peptides, and Proteins; Proteins; Biological Factors; Hydrolases; Enzymes; Enzymes and Coenzymes; Botulinum Toxins; Metalloendopeptidases; Endopeptidases; Peptide Hydrolases; Metalloproteases; Bacterial Proteins; Bacterial Toxins; Toxins, Biological; Botulinum Toxins, Type A
• Other Study ID Numbers: M21-417

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: AbbVie is committed to responsible clinical trial data sharing. This includes access to anonymized, individual and trial-level data (analysis data sets), as well as other information.
• IPD Sharing Time Frame: For details on when studies are available for sharing visit https://vivli.org/ourmember/abbvie/
• IPD Sharing Access Criteria: To learn more about the process, or to submit a request, visit the following link https://www.abbvieclinicaltrials.com/hcp/data-sharing/
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No