A Randomized, Double-blind, Placebo-controlled, Dose Ranging, Parallel, Multi-Centre, Phase II Study to Evaluate the Efficacy and Safety of MT921 in Subjects with Moderate to Severe Submental Fat

초록

BACKGROUND: Submental fat (SMF) is commonly treated with liposuction, surgery, or injectable drugs. Cholic acid, a primary bile acid, can induce lipolysis. OBJECTIVE: To evaluate the efficacy and safety of MT921, an injectable cholic acid formulation, for reducing moderate to severe SMF. METHODS: Subjects with moderate to severe SMF were randomized to receive MT921 1.0%/1.0 cm, MT921 1.5%/1.0 cm, MT921 1.5%/1.25 cm, or placebo. Primary endpoints were ≥1- and ≥2-grade improvements in clinician- and patient-assessed SMF Rating Scales at 4 weeks after the final treatment. Secondary endpoints included changes in SMFRS, patient satisfaction, Patient-Assessed Submental Fat Impact Scale, and SMF volume or thickness measured by MRI or calipers. Safety was assessed by adverse events, laboratory tests, and vital signs. RESULTS: In groups 1, 2, 3, and 4, respectively, ≥1-grade improvement in clinician-assessed SMFRS was achieved by 72.73%, 88.64%, 79.07%, and 48.78% of subjects, and ≥1-grade improvement in patient-assessed SMFRS by 77.27%, 88.64%, 79.07%, and 46.34%. Compared with placebo, MT921 showed favorable improvements in SMFRS responses, patient satisfaction, PA-SMFIS, and caliper-measured SMF thickness. MRI-measured SMF volume decreased in MT921-treated groups but not in the placebo group. Adverse events were more frequent with MT921 but were mostly mild or moderate. CONCLUSIONS: MT921 showed favorable efficacy signals for reducing moderate to severe SMF and was generally well tolerated. These findings support further evaluation of MT921, particularly the 1.5% formulation, in larger phase 3 trials with longer follow-up. © The Author(s) 2026. Published by Oxford University Press on behalf of The Aesthetic Society.