Dersimelagon is an investigational once-daily oral MC1R agonist being developed for erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP). These rare genetic disorders can cause severe pain and skin reactions after exposure to sunlight.

Tanabe submitted a New Drug Application to the U.S. Food and Drug Administration in June 2026. The filing is supported by the Phase 3 INSPIRE study, which reported significant improvements in the time patients could spend in sunlight before developing symptoms.

“Patients living with EPP or XLP face the devastating lifelong burden of severe reactions to sunlight, and there is a clear need for treatment options that can make a meaningful difference in their everyday lives,” says Christophe Bourdon, CEO of LEO Pharma.

Dersimelagon has received Fast Track and Orphan Drug designations from the FDA but remains investigational and has not been approved by any regulatory authority. The transaction is subject to customary closing conditions and applicable regulatory approvals.