MT-1 (Melanotan 1) — Research Overview
Chemical Name: [Nle4, D-Phe7]-alpha-melanocyte-stimulating hormone International Nonproprietary Name: Afamelanotide Also Known As: MT-1, Melanotan I, Melanotan-1, NDP-alpha-MSH, NDP-MSH, CUV-1647, CUV1647 FDA Brand Name: Scenesse (afamelanotide 16 mg implant, Clinuvel Pharmaceuticals) Structure: Synthetic linear tridecapeptide (13 amino acids) — identical to physiological alpha-melanocyte-stimulating hormone (alpha-MSH) with two strategic amino acid substitutions: L-norleucine (Nle) replaces methionine at position 4, and D-phenylalanine (D-Phe) replaces L-phenylalanine at position 7. The N-terminus is acetylated and the C-terminus is amidated, providing additional exopeptidase resistance. Molecular Weight: Approximately 1645 daltons Relationship to Natural alpha-MSH: Alpha-MSH is an endogenous 13-amino acid neuropeptide derived from proopiomelanocortin (POMC). Natural alpha-MSH binds MC1R and drives melanogenesis but is rapidly degraded by plasma enzymes. The two structural substitutions in afamelanotide confer dramatically enhanced metabolic stability and prolonged receptor occupancy — estimated to be 100 to 1,000 times more potent than natural alpha-MSH in melanogenic assays. Development History: First synthesized in the 1980s at the University of Arizona by Victor Hruby and Mac Hadley. Clinical development undertaken by Clinuvel Pharmaceuticals (formerly Epitan). First alpha-MSH analog to enter human clinical trials and the first melanocortin receptor agonist approved as a systemic therapeutic. FDA Approval: October 8, 2019 (NDA 210797) — to increase the amount of pain-free time spent in sunlight in adults with erythropoietic protoporphyria (EPP). EMA Approval: December 2014 — prevention of phototoxicity in adults with EPP. Label amendment approved September 2025 allowing year-round treatment without the previous annual implant limit. Australian TGA Approval: October 2020 — EPP. Orphan Drug Designation: Granted by FDA and EMA for EPP. WADA Status: Prohibited under S2 (peptide hormones, growth factors, related substances, and mimetics) Category: MC1R agonist / melanocortin receptor agonist / eumelanin synthesis inducer / photoprotective peptide / FDA-approved pharmaceutical / melanocortin research tool
Research Use Only — Disclaimer
The scientific literature on this page is provided strictly for educational and informational purposes. All Rogue Compounds products are intended for in-vitro laboratory research use only and are not approved by the FDA for human or animal consumption outside of the specific FDA-approved pharmaceutical indication described above (EPP, Scenesse formulation). The studies referenced below are independent third-party peer-reviewed publications. Rogue Compounds makes no claims that any product diagnoses, treats, cures, or prevents any disease or condition. Researchers are responsible for compliance with all applicable local, state, and federal regulations.
What Is MT-1 (Melanotan 1)?
MT-1, commercially known as afamelanotide and marketed as Scenesse, is a synthetic superpotent analog of alpha-melanocyte-stimulating hormone — the endogenous 13-amino acid neuropeptide that is the primary hormonal regulator of melanin synthesis in human skin. Developed in the 1980s through rational peptide design at the University of Arizona, MT-1 is the first and most extensively studied synthetic analog of the melanocortin system to reach clinical approval.
MT-1 is distinguished from all other compounds in this research catalog by its regulatory status: it is the first and only melanocortin receptor agonist to receive approval as a systemic therapeutic agent by any major regulatory authority globally. The FDA approved it in October 2019, the EMA in December 2014, and the Australian TGA in October 2020 — all for the indication of preventing phototoxicity in adults with erythropoietic protoporphyria. This approved clinical status, backed by multiple Phase 3 randomized controlled trials published in the New England Journal of Medicine and other high-impact journals, gives MT-1 a uniquely robust evidence base compared to most research peptides.
MT-1 differs from its structural relative Melanotan II (MT-2) in critically important ways. MT-1 is a linear peptide — it retains the natural linear tridecapeptide structure of alpha-MSH. MT-2 is a cyclic heptapeptide truncation that lacks the specificity of MT-1 and activates multiple melanocortin receptor subtypes, including MC3R and MC4R, producing CNS effects including sexual arousal, appetite suppression, and cardiovascular effects that MT-1 does not meaningfully produce at MC1R-relevant doses. MT-1’s relative selectivity for MC1R over MC3R and MC4R is what gives it a substantially cleaner side effect profile and made it the compound suitable for clinical development and regulatory approval, while MT-2 remained unregulated and clinically unapproved.
The Melanocortin System and MC1R Biology
To understand MT-1’s research significance, the melanocortin system must be understood in context. The melanocortins are a family of peptides derived from proopiomelanocortin (POMC) — a precursor protein that is proteolytically cleaved to generate alpha-MSH, beta-MSH, gamma-MSH, and adrenocorticotropin (ACTH), among other peptides. These melanocortin peptides act on a family of five G-protein-coupled receptors: MC1R through MC5R.
MC1R is the primary receptor expressed on melanocytes in the skin and is the central regulator of melanogenesis. MC1R is also expressed on keratinocytes, fibroblasts, endothelial cells, neutrophils, lymphocytes, and cells of the immune system — accounting for the multiple biological effects of MC1R agonism beyond pigmentation.
MC1R is among the most polymorphic genes in the human genome. Many variant alleles of MC1R — particularly prevalent in fair-skinned, red-haired populations of Northern European ancestry — result in a non-functional or partially functional receptor. Individuals with loss-of-function MC1R variants produce predominantly pheomelanin (the yellow-red photocarcinogenic pigment) rather than eumelanin (the brown-black photoprotective pigment), giving them the fair-skinned, freckled, sun-sensitive, melanoma-prone phenotype. The association of MC1R loss-of-function variants with dramatically elevated melanoma risk (2-fold to over 4-fold depending on the specific variant and number of alleles) has made MC1R a major cancer research target.
When MT-1 binds MC1R, it activates the receptor independently of UV radiation — producing eumelanin synthesis without the DNA damage that accompanies UV-induced tanning. This UV-independent eumelanogenesis is the pharmacological basis for MT-1’s photoprotective effects and its clinical utility in EPP, a condition where UV stimulation of tanning is not possible because even sub-erythemogenic light exposure causes excruciating pain.
Erythropoietic Protoporphyria — The Approved Indication
Erythropoietic protoporphyria (EPP) is a rare autosomal recessive inborn error of heme metabolism caused by partial deficiency of ferrochelatase — the enzyme that inserts iron into protoporphyrin IX to form heme. The resulting accumulation of protoporphyrin IX in erythroid cells causes severe, excruciating phototoxic pain upon light exposure, typically beginning in early childhood. EPP patients develop burning, stinging, and throbbing pain that can persist for days after even brief sunlight or indoor artificial light exposure. The condition dramatically limits daily activities — patients cannot go outdoors, drive, sit near windows, or tolerate fluorescent lighting without severe consequences. Prior to afamelanotide, no effective therapy for EPP existed.
The mechanism by which afamelanotide treats EPP is straightforward and well characterized: by activating MC1R on melanocytes independently of UV exposure, afamelanotide drives eumelanin synthesis and increases epidermal eumelanin density. Eumelanin is a broadband light absorber that reduces penetration of all wavelengths of light — including the visible light wavelengths (400-650 nm) that activate protoporphyrin IX in EPP patients — into the skin. This increased melanin acts as an endogenous optical filter, protecting sub-epidermal tissues from the wavelengths that cause protoporphyrin phototoxicity. EPP patients with greater baseline melanin density (darker skin) have a milder disease phenotype — a clinical observation that directly supports the therapeutic rationale.
Mechanism of Action
MC1R agonism and eumelanogenesis: MT-1 binds MC1R on melanocytes as a full agonist, activating the receptor through Gs protein coupling. Receptor activation elevates intracellular cAMP, which activates protein kinase A (PKA), which phosphorylates the master melanogenic transcription factor MITF (microphthalmia-associated transcription factor). Activated MITF drives transcription of melanogenic enzymes including tyrosinase (the rate-limiting enzyme in melanin biosynthesis), TRP-1, and TRP-2. This enzymatic cascade converts L-tyrosine through DOPA to DOPA-quinone and ultimately to eumelanin within melanosomes, which are then transferred to surrounding keratinocytes. The eumelanin produced fills the keratinocyte population of the epidermis, increasing the optical density of the skin and providing broadband photoprotection.
UV-independent activation: Unlike natural UV-induced tanning — which requires UV-induced DNA damage to trigger p53-mediated POMC upregulation and alpha-MSH release — MT-1’s eumelanin induction is UV-independent. This allows photoprotective pigment to be generated before UV exposure, providing preemptive rather than reactive photoprotection.
DNA repair enhancement: In addition to the physical UV-filtering provided by eumelanin, MC1R signaling through alpha-MSH and its analogs has been documented to enhance nucleotide excision repair (NER) of UV-induced DNA damage — the DNA repair pathway responsible for removing cyclobutane pyrimidine dimers and other UV-induced photoproducts. This direct DNA repair-enhancing effect is mechanistically distinct from and additive to the physical photoprotection provided by eumelanin, and may contribute to the skin cancer chemopreventive potential being investigated in clinical research.
Antioxidant activation: MC1R signaling upregulates antioxidant defenses including superoxide dismutase and scavenging of reactive oxygen species. Eumelanin itself has antioxidant properties — quenching singlet oxygen, scavenging superoxide radicals, and reducing oxidative DNA damage. This antioxidant dimension of afamelanotide’s pharmacology provides a third photoprotective mechanism beyond physical UV filtering.
Anti-inflammatory immunomodulation: MC1R is expressed on immune cells including neutrophils, lymphocytes, macrophages, and mast cells. MT-1 binding to MC1R on these cells modulates the cytokine milieu — reducing pro-inflammatory mediators and contributing to the anti-inflammatory effects observed clinically in conditions including acne and solar urticaria. NF-kB suppression through MC1R signaling in immune cells parallels the anti-inflammatory mechanism of alpha-MSH in the central nervous system.
Published Research
Study 1 — Phase 3 Pivotal Trial: Afamelanotide for Erythropoietic Protoporphyria (NEJM)
Authors: Langendonk JG, Balwani M, Anderson KE et al. (Multi-center EU and US teams) Year: 2015 Journal: New England Journal of Medicine PMID: 26132941 Full text: https://www.nejm.org/doi/full/10.1056/NEJMoa1411481
This landmark New England Journal of Medicine publication reported the combined results of two multicenter randomized double-blind placebo-controlled Phase 3 trials — the definitive efficacy data that supported regulatory approval in both the EU and the US.
Two parallel Phase 3 trials enrolled 74 patients in the European Union and 94 patients in the United States. Patients were randomized 1:1 to receive subcutaneous implants containing 16 mg of afamelanotide or placebo every 60 days.
In both trials, afamelanotide treatment was associated with significantly increased duration of sun exposure without pain and increased time to first symptoms of phototoxicity compared to placebo.
Quality of life as measured by the EPP-QOL questionnaire showed marked improvements in the afamelanotide group. In the US trial, mean change in EPP-QOL score at day 60 was 44.0 in the afamelanotide group versus 23.4 in the placebo group (P less than 0.001). At day 120 it was 49.8 versus 30.4 (P less than 0.001). Scores remained significantly higher in the afamelanotide group through day 180 (P equal to 0.02).
Afamelanotide had an acceptable side effect and adverse event profile. No drug-related serious adverse events were reported. Common adverse events were headache, nausea, and implant-site reactions.
The authors noted that afamelanotide had already been approved on a compassionate-use basis in Italy and Switzerland for over 8 years with no late effects reported, and that long-term monitoring of 115 patients showed sustained quality of life improvement (EPP-QOL 74% versus 31% at baseline) — providing a critically important long-term safety and efficacy perspective.
Study 2 — First Human Clinical Tanning Trials: Melanotan-1 Phase 1 Safety with UV Synergy
Authors: Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME (University of Arizona) Year: 2004 Journal: Archives of Dermatology PMID: 15262693 Full text: https://pubmed.ncbi.nlm.nih.gov/15262693/
This foundational publication reported three Phase 1 clinical trials of MT-1 — among the earliest published human data for any synthetic melanocortin peptide and the first systematic safety characterization of melanotan-1 combined with UV exposure.
Three open-label studies were conducted at dermatology clinics at the Arizona Health Sciences Center examining MT-1 at doses of 0.08 and 0.16 mg/kg subcutaneously over 10 days combined with varying UV-B exposures and sunlight.
The studies demonstrated that MT-1 was well tolerated across dose levels, with the primary adverse effects being transient nausea and facial flushing at higher doses — a profile consistent with what has been documented in subsequent trials.
MT-1 combined with UV-B light or sunlight appeared to act synergistically in the tanning response — low UV doses that would not produce visible tanning alone produced significant pigmentation when combined with MT-1 pre-treatment, demonstrating the priming effect of MC1R activation on melanocyte UV responsiveness.
The studies established the subcutaneous route as the appropriate delivery method, with full bioavailability confirmed. Oral and transdermal routes did not produce measurable plasma concentrations or pigmentation responses — informing the implant formulation strategy ultimately used for Scenesse.
Study 3 — MC1R Variant Alleles and MT-1 Melanin Synthesis: Those Most in Need Benefit Most
Authors: Barnetson RS, Ooi TK, Zhuang L, Halliday GM et al. (University of Sydney) Year: 2006 Journal: Journal of Investigative Dermatology PMID: 16293341
This study directly examined whether MT-1 could overcome the MC1R dysfunction associated with variant alleles — addressing the most clinically relevant population for photoprotective therapy.
Subjects with MC1R variant alleles — the fair-skinned, poorly tanning, melanoma-susceptible population — received MT-1 treatment and showed significant increases in melanin content of skin as measured by reflectance spectrophotometry.
Crucially, the melanin increase was achieved even in subjects whose MC1R variant alleles reduce responsiveness to natural alpha-MSH — demonstrating that MT-1’s superpotency overcomes the reduced receptor efficiency of variant alleles, reaching eumelanogenesis in the population that most requires photoprotective pigmentation.
The authors concluded that MT-1 effectively increases melanin content in those individuals with MC1R variant alleles and therefore those most in need of photoprotection — establishing the pharmacological rationale for MT-1 as a photoprotective and potentially chemopreventive agent specifically in the high-risk fair-skinned population.
Study 4 — Vitiligo: Afamelanotide Plus NB-UVB Produces Superior Repigmentation
Authors: Lim HW, Grimes PE, Agbai O, Hamzavi I, Henderson M, Haddican M, Linkner RV, Lebwohl M (JAMA Dermatology multicenter trial) Year: 2015 Journal: JAMA Dermatology Referenced via: JAMA Dermatol. 2015;151(1):42-50
This randomized multicenter Phase 2 trial was the first controlled demonstration that afamelanotide combined with phototherapy produces significantly superior outcomes in vitiligo compared to phototherapy alone — establishing a second major clinical development direction for MT-1.
Patients with non-segmental vitiligo were randomized to receive either afamelanotide subcutaneous implants combined with narrowband ultraviolet B (NB-UVB) phototherapy, or NB-UVB monotherapy.
At day 168, repigmentation was 48.64% in the combination group versus 33.26% with NB-UVB alone — a statistically and clinically meaningful difference.
Onset of repigmentation was faster in the combination group: 41 versus 61 days on the face and 46 versus 69 days on the upper extremities — demonstrating that afamelanotide not only increases final repigmentation but accelerates the rate of response to phototherapy.
The biological rationale is well-established: afamelanotide activates melanocyte MC1R, driving proliferation, migration, and eumelanogenic differentiation of residual and reservoir melanocytes — complementing NB-UVB’s immunomodulatory effects on the autoimmune destruction that underlies vitiligo.
A Phase 3 pivotal trial for vitiligo (CUV105) completed enrollment of over 200 patients across three continents in 2025, with results expected in 2026 — positioning afamelanotide as potentially the first systemic peptide therapy for vitiligo.
Study 5 — Long-Term Observational Study: 115 EPP Patients, Up to 8 Years of Afamelanotide
Authors: Biolcati G, Marchesini E, Sorge F, Barbieri L, Schneider-Yin X, Minder EI Year: 2015 Journal: British Journal of Dermatology Referenced via: Br J Dermatol. 2015;172:1601-12
This long-term observational study of 115 EPP patients receiving afamelanotide on compassionate-use basis (in Italy and Switzerland) provided the most extensive real-world safety and efficacy data for any melanocortin peptide in clinical history — the longest-running clinical observation of an MC1R agonist in human patients.
Patients received afamelanotide for up to 8 years continuously with no late effects reported — directly establishing the long-term safety of chronic MC1R agonism at therapeutic doses.
No immunogenic potential was identified over this extended observation period — ruling out antibody formation against the synthetic peptide as a clinical concern.
Quality of life improvements were sustained over time (EPP-QOL 74% versus 31% at baseline) — confirming that the clinical benefit of afamelanotide is maintained with ongoing treatment and does not diminish due to tachyphylaxis or tolerance.
An immunogenic potential being excluded is particularly significant: unlike many biological therapies where antibody development limits long-term efficacy, afamelanotide has not been associated with anti-drug antibody formation despite years of continuous subcutaneous administration.
MT-1 vs MT-2: Critical Research Context
The distinction between MT-1 (afamelanotide) and MT-2 is critical for accurate representation and must be stated clearly in any research context.
MT-1 (Melanotan 1, afamelanotide) is a linear tridecapeptide with relative selectivity for MC1R. Its primary pharmacological effects are eumelanogenesis (skin tanning) and photoprotection. At clinically studied doses, MT-1 does not produce significant CNS effects, sexual arousal, appetite suppression, or the cardiovascular effects associated with MC4R activation.
MT-2 (Melanotan 2) is a cyclic heptapeptide truncation ([Nle4, D-Phe7]-alpha-MSH cyclo(5-10)) that is less receptor-selective, activating MC3R and MC4R at relevant doses in addition to MC1R. MC4R activation produces sexual arousal, appetite suppression, nausea, and other CNS effects. MT-2 has no approved clinical indication in any jurisdiction and has not completed the clinical development programs that afamelanotide/MT-1 has.
For research applications specifically studying MC1R biology, melanogenesis, photoprotection, or the EPP disease model, MT-1 is the pharmacologically appropriate tool. MT-2’s broader melanocortin receptor profile makes it a less selective research tool for isolated MC1R studies.
Additional Clinical Research Directions for MT-1
Beyond EPP and vitiligo, afamelanotide has been investigated in Phase 2 clinical settings for solar urticaria (in which it reduced weal formation through increased melanization), mild-to-moderate acne vulgaris (in which it reduced inflammatory lesion counts), photodynamic therapy phototoxicity mitigation in oncology patients, and non-melanoma skin cancer prevention in high-risk populations (squamous cell carcinoma and actinic keratosis). The breadth of conditions investigated reflects the fundamental biology of MC1R in skin physiology and photoprotection.
The DNA repair enhancement mechanism — published evidence that alpha-MSH and its analogs enhance nucleotide excision repair of UV-induced photoproducts — has particularly driven interest in skin cancer chemoprevention applications. If afamelanotide can both reduce UV penetration into the skin (through eumelanin) and enhance repair of UV damage that does occur (through NER activation), the combination represents a potentially powerful dual-mechanism chemopreventive strategy for the high-risk MC1R variant allele population.
Current Research Status
Afamelanotide (MT-1, Scenesse) is FDA-approved, EMA-approved, and TGA-approved for EPP. Phase 3 clinical trials are ongoing for vitiligo (CUV105, results expected 2026). Research continues into skin cancer chemoprevention, solar urticaria, and other photosensitivity disorders. Long-term safety is well-established from 8+ years of compassionate-use observation and post-marketing surveillance.
As a research peptide (outside pharmaceutical formulation), MT-1 is a WADA-prohibited substance and is not approved for non-EPP human therapeutic use.
Reconstitution Note
MT-1 for research use is supplied as lyophilized powder. Bacteriostatic water is the standard reconstitution solvent. MT-1 dissolves readily in aqueous solution. Protect from light — the peptide contains aromatic amino acid residues sensitive to photooxidation. Note that the pharmaceutical Scenesse formulation is a biodegradable subcutaneous implant delivering 16 mg over approximately 60 days through controlled release — a pharmacokinetic profile very different from solubilized MT-1 prepared for research use. Always confirm the recommended solvent against the specific lot datasheet before reconstitution.
In-Use Period and Storage
Before Reconstitution — Lyophilized Powder
Rogue Compounds stores all products refrigerated prior to shipping to maintain compound integrity from production through to delivery. Upon receipt researchers should store vials at 2 to 8 degrees Celsius immediately. Keep vials sealed, dry, and away from direct light until ready for use. Do not freeze. Repeated freeze-thaw cycling has been documented in peer-reviewed pharmaceutical formulation literature to accelerate structural degradation even in dry powder form, potentially compromising molecular integrity and experimental reproducibility.
Why We Refrigerate Instead of Freeze
Freezing and thawing introduces mechanical and osmotic stress at the molecular level. Published pharmaceutical research identifies freeze-thaw cycling as a significant risk factor for loss of structural integrity in peptides and protein-based compounds. To protect compound quality at every stage of handling and fulfillment, Rogue Compounds maintains refrigerated rather than frozen cold chain storage throughout the entire process.
After Reconstitution — Liquid Solution
Store reconstituted solutions refrigerated at 2 to 8 degrees Celsius immediately after preparation. Protect from light at all stages — aromatic amino acid residues in MT-1 are susceptible to photooxidation. Avoid repeated freeze-thaw cycles. Use within the timeframe recommended for the individual compound. Label each aliquot with the compound name, concentration, date of reconstitution, and diluent used. Discard any solution that shows visible particulate matter, discoloration, or signs of degradation.
Note: Storage and in-use recommendations on this page are provided as general laboratory guidance based on standard peptide handling practices documented in peer-reviewed pharmaceutical literature. Researchers should always refer to the individual compound’s published research literature and datasheet for any specific requirements. All products sold by Rogue Compounds are intended strictly for in-vitro laboratory research use only.
Available from Rogue Compounds
View the MT-1 product page: https://roguecompounds.com/product/mt-1/