The US FDA has accepted for filing and granted Priority Review to the New Drug Application (NDA) for dersimelagon, an investigational oral melanocortin 1 receptor (MC1R) agonist being developed for erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP). The Prescription Drug User Fee Act (PDUFA) action date is set for the end of February 2027.
Denmark-based LEO Pharma, which completed its acquisition of worldwide rights to dersimelagon from Japan-based Tanabe Pharma simultaneously with the regulatory announcement, paid up to USD 435 million in upfront and near-term milestone payments for the asset, plus potential downstream milestones and double-digit up to mid-teens tiered royalties on net sales.
The NDA is supported by the global, randomized, double-blind, placebo-controlled Phase III INSPIRE study, in which Tanabe Pharma reported that dersimelagon demonstrated statistically significant and clinically meaningful outcomes across primary and secondary endpoints. The primary endpoint measured change from baseline in average daily sunlight exposure time to first prodromal symptoms — burning, tingling, itching, or stinging — at week 16 in 165 adult and adolescent patients aged 12 to 75. The trial also enrolled adolescents, a population for which no pharmacological treatment is currently approved. Most adverse events were mild or moderate in severity, according to Tanabe. The Phase III data were presented as a late-breaker at the 2026 American Academy of Dermatology Annual Meeting.
The only currently approved pharmacological therapy for EPP is afamelanotide (Scenesse), a subcutaneous implant developed by Australia-based Clinuvel Pharmaceuticals that requires periodic in-office administration. The FDA label covers adults with EPP, while XLP has no specifically approved pharmacological treatment in the US. Dersimelagon's once-daily oral formulation and development across both EPP and XLP distinguish it from afamelanotide, and LEO said the drug would, if approved, represent the first oral therapy for either condition. Disc Medicine is also developing the oral GlyT1 inhibitor bitopertin for EPP; its NDA received a Complete Response Letter in February 2026, and the company expects Phase III APOLLO data in Q4 2026 to support a planned response to the FDA.