Melanotan I

Two multicenter, randomized, double-blind, placebo-controlled Phase 3 trials evaluated subcutaneous 16 mg afamelanotide implants administered every 60 days in adults with erythropoietic protoporphyria (EPP), a rare inherited disorder of heme biosynthesis. In the U.S. study (n=94), the median duration of pain-free time over 180 days was 69.4 hours in the afamelanotide group versus 40.8 hours in the placebo group (P=0.04). In the EU study (n=74), pain-free time over 270 days was 6.0 hours versus 0.8 hours (P=0.005), and the number of phototoxic reactions was lower in the afamelanotide group (77 vs. 146, P=0.04). Pharmacodynamically, the implants were associated with increased eumelanin density measured by reflectance spectrophotometry, consistent with MC1R-driven melanogenesis. Adverse events were predominantly mild and included nausea, headache, and implant-site reactions.

People with EPP are born with a genetic difference that makes their skin extremely sensitive to light, even brief sun exposure can cause severe pain. Researchers gave participants a small implant under the skin that slowly released MT-1 (afamelanotide). The peptide signals melanocytes — the body's pigment-producing cells — to make more of the dark pigment eumelanin, which absorbs and scatters light before it can damage tissue. In two large trials, participants who got the implants could spend more time in sunlight without pain and had fewer painful reactions than participants who got placebo implants. The implants were generally well tolerated.

This randomized, multicenter, parallel-group trial enrolled 55 adults with generalized non-segmental vitiligo. Participants received either combination therapy (monthly subcutaneous afamelanotide implants plus narrowband UV-B phototherapy three times weekly) or narrowband UV-B monotherapy for six months, followed by a six-month observation phase. The combination arm showed faster and more extensive repigmentation, with statistically superior responses on the Vitiligo Area Scoring Index at multiple time points (days 56, 84, 112, and 168). Investigators attributed the additive effect to MC1R-mediated melanocyte stimulation by afamelanotide, complementing the melanocyte proliferation and migration effects of NB-UVB. Diffuse skin hyperpigmentation in the combination group was the most common adverse event and resolved after discontinuation.

Vitiligo causes patches of skin to lose pigment when melanocytes — the cells that make pigment — are damaged or destroyed. The standard light-based protocol (narrowband UV-B) coaxes any remaining melanocytes to multiply and refill the patches. Researchers tested whether adding MT-1 (afamelanotide), which directly signals melanocytes to produce pigment, would speed up the process. In the combination group, color returned to the affected skin faster and more completely than in the light-therapy-only group. The combination also caused some general darkening of the surrounding skin, which faded after the implants were stopped.