LEO Pharma agreed to acquire rights to dersimelagon from Tanabe Pharma in a deal potentially worth up to $435 million, adding a late-stage candidate targeting rare sunlight-sensitive skin diseases. If approved, LEO said the drug could become the first oral treatment for erythropoietic protoporphyria and X-linked protoporphyria. The asset comes after a Phase 3 dataset earlier this year and with U.S. regulatory review underway, including Fast Track and Orphan Drug designations reported by the parties. For LEO, the acquisition is positioned as a way to broaden its dermatology portfolio with an oral option that could shift patient treatment patterns away from less convenient regimens. The move also reinforces how mid-to-large dermatology specialists are building around late-stage rare disease assets as a recurring growth lever.