LEO Pharma has agreed to acquire worldwide rights to dersimelagon from Tanabe Pharma. Dersimelagon is an oral, once-daily small MC1R agonist being developed for EPP and XLP.
EPP and XLP are rare and severe genetic diseases that cause severe sunlight-induced skin damage and can significantly limit patients’ ability to spend time outdoors. Symptoms may include skin rash, swelling, redness, burning sensations and, in some cases, liver damage. Dersimelagon is designed to increase skin melanin, helping reduce sunlight penetration and protect against phototoxic reactions.
“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,” said Christophe Bourdon, CEO of LEO Pharma. “By addressing a clear unmet need in a rare skin disease, dersimelagon represents a compelling opportunity to expand our rare dermatology pipeline with a late-stage oral therapy candidate.”
If approved, dersimelagon would represent the first oral therapy for the treatment of EPP and XLP and help address an area of significant unmet need.
Under the terms of the agreement, LEO Pharma will acquire worldwide rights to dersimelagon from Tanabe Pharma for up to $435m in up front and near-term milestone payments together with potential down- stream milestones and tiered royalties on net sales.
Dersimelagon has been granted both US FDA Fast Track Designation and Orphan Drug Designation, and an NDA for the treatment of EPP and XLP was submitted to the US FDA for regulatory review in June 2026, but has not yet been approved by the FDA or any other regulatory agency.
“EPP and XLP are devastating lifelong diseases that can severely limit patients’ ability to live everyday lives free from sunlight-induced pain, and dersimelagon has the potential to become an important new treatment option,” said Akihisa Harada, CEO of Tanabe Pharma.
Earlier this year, Tanabe Pharma announced results from the global, randomised, double-blind, placebo-controlled phase 3 INSPIRE study of EPP and XLP that showed dersimelagon demonstrated statistically significant and clinically meaningful outcomes across primary and secondary endpoints, including key functional outcomes such as a significant prolongation of average daily sunlight exposure time to first prodromal symptoms. The phase 3 data was presented as a late breaker at the 2026 American Academy of Dermatology Annual Meeting (AAD).