This example interventional study record describes a randomized Phase 2 clinical trial evaluating investigational Melanotan II (MT-II) as an adjunct to standard NB-UVB phototherapy for repigmentation in adults with stable nonsegmental vitiligo.

Vitiligo is characterized by acquired depigmented macules and patches due to the loss of functional melanocytes. Narrowband UV-B (NB-UVB) phototherapy is a common treatment that can promote repigmentation, but responses may be incomplete and can take months. Melanotan II (MT-II) is a synthetic cyclic melanocortin receptor agonist with activity at melanocortin receptors involved in melanogenesis (pigment production). This example trial evaluates the safety and preliminary efficacy of adding investigational MT-II to standardized NB-UVB phototherapy compared with placebo plus NB-UVB in adults with stable nonsegmental vitiligo. Participants are randomized 1:1 and treated for 24 weeks, with standardized digital photography, clinician-rated scoring, and objective colorimetry performed at prespecified visits. Safety monitoring includes adverse event collection, vital signs, and focused skin examinations (including monitoring of nevi). A follow-up visit occurs 4 weeks after the final dose to assess ongoing safety.

Inclusion Criteria:

• Adults aged 18-65 years able to provide informed consent.
• Clinical diagnosis of nonsegmental vitiligo with stable disease (no new lesions and no lesion expansion) for >=6 months prior to screening.
• Total body surface area involvement between 3% and 20% (inclusive), with at least two measurable target lesions suitable for standardized photography and colorimetry.
• Willingness to undergo NB-UVB phototherapy per protocol and to avoid non-study vitiligo treatments during the study.
• For participants of childbearing potential: agreement to use effective contraception during the study and for a protocol-specified period after the last dose.

Exclusion Criteria:

• Segmental vitiligo as the predominant type, or rapidly progressive disease within the past 6 months.
• Use of systemic immunosuppressive therapy, systemic corticosteroids, or JAK inhibitors within 8 weeks prior to screening (time windows may vary by drug/class).
• Use of topical calcineurin inhibitors or topical corticosteroids on target lesions within 2 weeks prior to baseline.
• Prior treatment with afamelanotide or melanotan (including Melanotan II) within 6 months prior to baseline.
• History of melanoma, dysplastic nevus syndrome, or other high-risk skin cancer history requiring close surveillance, as judged by the investigator.
• Clinically significant uncontrolled hypertension, cardiovascular disease, or any condition that, in the investigator's judgment, increases risk with melanocortin agonist exposure.
• Pregnant or breastfeeding.
• Known hypersensitivity to study product components.
• Participation in another interventional clinical trial within 30 days prior to screening.

Investigational product and placebo are identical in appearance and packaging. Randomization codes are held by an unblinded pharmacist/third party. Outcome assessments are performed by blinded evaluators using standardized photographs and scoring rules.