Vitiligo is a common skin disorder in which the pigment producing cells of the skin (melanocytes) are absent or demonstrate lack of activity. As a result, lighter, depigmented patches of skin (target lesions) appear in different parts of the body due the lack of melanin (pigment). The exact cause of vitiligo is unknown, but it is generally recognised that an autoimmune component plays a role in this disease. Between 0.1-2% of the global population is affected by vitiligo affecting all races. Vitiligo causes significant psychological and emotional distress.
Vitiligo is traditionally separated into two clinical forms: nonsegmental, or generalised, vitiligo (NSV) and segmental vitiligo (SV), which present with distinctive clinical features and natural histories.
NSV is the most common form of the disease, accounting for 72-95% of the cases. The vitiliginous lesions are usually symmetrically distributed and new patches may appear throughout the patient’s life. The disease is progressive with flare-ups. NSV is frequently associated with personal or family history of auto-immunity.
Alpha melanocyte stimulating hormone (α-MSH), a natural (physiological) hormone which is produced by skin cells when they are exposed to UV light, has been shown to play several vital roles in promoting the return of pigment (repigmentation) to patches of vitiliginous skin. Along with other factors, it stimulates immature melanocytes, known as melanocyte stem cells, to multiply and develop into fully functioning melanocytes. It also assists these cells in their migration, from their reservoir within hair follicles, to the epidermis of the skin. Once at the epidermis, α-MSH further affects the melanocytes, continuously stimulating them to produce melanin through the expression of genes critical to this process.
SCENESSE® (afamelanotide) is an analogue of α-MSH which mimics the effects of the naturally occurring hormone. It is anticipated that treatment of vitiligo patients with SCENESSE® could aid in the repigmentation of lesions by these same mechanisms – enhancing the increase and growth of melanocytes, assisting in their migration to depigmented areas of skin and activating pigment production within these regions.
SCENESSE’s effects are being investigated in combination with the physical stimulant narrow-band ultraviolet B phototherapy (NB-UVB). Ultraviolet B radiation is a potent melanocyte stimulant and NB-UVB is currently seen as one of the most effective therapies available for vitiligo. The addition of SCENESSE® to this treatment modality is expected to assist the repigmentation process initiated by NB-UVB. It is anticipated that repigmentation of the skin will be achieved more rapidly, allowing for a reduction in the patient’s exposure to UV light; this could potentially decrease the risk of NB-UVB side effects.