LEO Pharma Announced Tuesday August 18, 2026 an Agreement to Acquire Worldwide Rights to Dersimelagon (Formerly MT-7117), a Selective Melanocortin-1 Receptor (MC1R) Agonist Small-Molecule Compound Being Developed for Erythropoietic Protoporphyria (EPP) and X-Linked Erythropoietic Protoporphyria (XLEPP), From Japanese Drugmaker Mitsubishi Tanabe Pharma; Dersimelagon Is Currently in Phase 3 Trials Across Multiple Rare Photodermatoses Indications and Represents an Oral Alternative to the Currently-Approved Injectable Melanocortin-Axis Therapies Including Clinuvel's Scenesse (Afamelanotide, an Alpha-MSH Analog Peptide for EPP) and Rhythm Pharmaceuticals' IMCIVREE (Setmelanotide, an MC4R Agonist Peptide for Rare Genetic Obesity Syndromes and Acquired Hypothalamic Obesity)
LEO Pharma announced Tuesday August 18, 2026 an agreement to acquire worldwide rights to dersimelagon (formerly MT-7117) from Japanese drugmaker Mitsubishi Tanabe Pharma. Dersimelagon is a selective melanocortin-1 receptor (MC1R) agonist small-molecule compound being developed for erythropoietic protoporphyria (EPP) and X-linked erythropoietic protoporphyria (XLEPP), rare inherited photodermatoses in which patients develop severe skin pain and burning after light exposure. Dersimelagon is currently in Phase 3 trials across multiple rare photodermatoses indications. The mechanism: MC1R agonism stimulates skin cells (melanocytes) to produce more melanin, which absorbs light and reduces the pain-generating reaction to sun exposure that characterizes EPP. Dersimelagon represents an oral small-molecule alternative to the currently-approved injectable melanocortin-axis therapies including Clinuvel's Scenesse (afamelanotide, an alpha-MSH analog peptide administered as a subcutaneous implant for EPP, approved US 2019) and adjacent to Rhythm Pharmaceuticals' IMCIVREE (setmelanotide, an MC4R agonist peptide for rare genetic obesity syndromes and acquired hypothalamic obesity, approved US 2020 with the acquired hypothalamic obesity extension approved June 2026). The LEO Pharma acquisition extends the melanocortin therapeutic franchise landscape and positions LEO for a broader dermatology and rare-disease portfolio alongside its existing psoriasis and atopic dermatitis commercial franchises. Financial terms were not fully disclosed. The transaction adds to the growing melanocortin-axis drug development activity across peptide (afamelanotide, setmelanotide, melanotan II) and small-molecule (dersimelagon) modalities.