Melanotan II (MT-II) as an Adjunct to NB-UVB Phototherapy for Repigmentation in Stable Nonsegmental Vitiligo

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.