Spesolimab

Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are two rare genetic conditions that cause severe, painful skin reactions under exposure to sunlight and certain wavelengths of artificial light. Credit: PeopleImages/Shutterstock.com. LEO Pharma has agreed to buy the worldwide rights to Tanabe Pharma’s drug in development for photosensitive genetic disorder treatment, bolstering the Danish company’s pipeline that has already undergone expansion this year. As per the deal, LEO is outlaying up to $435m in upfront and near-term milestone payments for global rights to Tanabe’s dersimelagon. The Japanese biopharma is also eligible for potential downstream milestones and tiered royalties on net sales if the drug wins approval. A route to market may not be far off. Dersimelagon is already under US Food and Drug Administration (FDA) review and is on an expedited regulatory process owing to its fast track and orphan drug designations. Dersimelagon is designed to treat erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) – two rare genetic conditions that cause severe, painful skin reactions under exposure to sunlight and certain wavelengths of artificial light. The disorders are caused by the buildup of a molecule called protoporphyrin in the body, which acts as a strong phototoxic agent. The protein absorbs light energy and sets off a chemical reaction that results in burning pain. Tanabe’s dersimelagon is a once-daily oral pill under evaluation in 50mg and 100mg doses. The small MC1R agonist works by increasing skin melanin, helping to reduce sunlight penetration and protect against phototoxic reactions. Results from a Phase III trial (NCT06144840) announced by Tanabe earlier this year demonstrated dersimelagon’s ability to prolong the average time between sunlight exposure and first manifestation of symptoms such as burning, tingling, or itching – hitting the study’s primary endpoint. If approved, dersimelagon would represent the first oral therapy for the treatment of EPP and XLP. A subcutaneous implant of Scenesse (afamelanotide) is already approved for EPP, though the availability of a pill would mark a significant advancement of treatment options for patients. It is hard to definitively state the rarity of the two diseases. Combined global prevalence is estimated between one in 57,000 and one in 200,000 people for EPP and XLP, respectively. LEO’s CEO, Christophe Bourdon, said: “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. “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.” The rights acquisition marks another recent bolstering of LEO’s rare disease pipeline. In May 2026, the Danish drugmaker spent $50 upfront to buy Replay , a gene therapy company developing treatments for rare genetic dermatological conditions. LEO also secured the rights to Boehringer Ingelheim’s psoriasis drug Spevigo (spesolimab) for $105m in July last year. In a statement announcing the Tanabe deal, LEO said the acquisition reflects its strategy to “strengthen its medical dermatology portfolio through targeted partnerships, acquisitions, and external innovation, with rare dermatology as a key focus area.”

Acquisition adds dersimelagon to LEO Pharma’s rare dermatology pipeline, an investigational once-daily oral melanocortin 1 receptor (MC1R) agonist for erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) that has completed Phase 3 development and for which a New Drug Application (NDA) has been submitted to U.S. Food and Drug Administration (FDA) for review in June 2026. 1 Leverages LEO Pharma's six decades of dermatology expertise to advance innovation for patients with rare skin diseases through the addition of this oral late-stage asset, building on LEO Pharma’s recent acquisition of Replay and partnership with Boehringer Ingelheim for Spevigo® (spesolimab). EPP and XLP are rare, devastating lifelong genetic disorders that cause severe sunlight-induced skin pain, as well as rash, swelling, redness, burning sensations and, in some cases, liver damage. 2,3 Under the terms of the agreement, LEO Pharma will acquire worldwide rights to dersimelagon from Tanabe Pharma for up to USD 435 million in up front and near-term milestone payments together with potential downstream milestones and tiered royalties on net sales. BALLERUP, Denmark--(BUSINESS WIRE)--LEO Pharma, a global leader in medical dermatology delivering innovative solutions for skin disease, today announces that it has entered into an agreement 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. 2,3 "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, 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. This acquisition is closely aligned with our strategy of identifying and investing in high-impact innovation in medical dermatology, where LEO Pharma brings deep disease understanding, and a global commercial footprint to bring this therapy to patients." “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. “LEO Pharma’s established expertise in medical dermatology and global reach make it the ideal partner to realize the full potential of dersimelagon and, if approved, bring this innovative treatment to patients.” The acquisition reflects LEO Pharma’s strategy to continue to strengthen its medical dermatology portfolio through targeted partnerships, acquisitions, and external innovation, with rare dermatology as a key focus area. Building on the 2025 partnership with Boehringer Ingelheim for Spevigo® (spesolimab) and the recent acquisition of Replay’s next-generation HSV gene therapy platform, LEO Pharma continues to pursue opportunities in rare skin diseases with high unmet need. This includes key innovation markets such as the U.S. and Japan, where the company’s dermatology expertise and global capabilities can help advance new treatment options for patients. Dersimelagon has been granted both U.S. FDA Fast Track Designation and Orphan Drug Designation, and an NDA for the treatment of EPP and XLP was submitted to the U.S. FDA for regulatory review in June 2026, but has not yet been approved by the FDA or any other regulatory agency. Dersimelagon’s safety and efficacy have not been established by any regulatory authority. 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. Earlier this year, Tanabe Pharma announced results from the global, randomized, double-blind, placebo-controlled Phase 3 INSPIRE study of EPP and XLP which 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. 4 The Phase 3 data was presented as a late breaker at the 2026 American Academy of Dermatology Annual Meeting (AAD). Under the terms of the agreement, LEO Pharma will acquire worldwide rights to dersimelagon from Tanabe Pharma for up to USD 435 million in up front and near-term milestone payments together with potential downstream milestones and tiered royalties on net sales. The transaction is subject to customary closing conditions, including applicable regulatory approvals. The acquisition is expected to increase LEO Pharma’s investments in 2026 for pre-launch activities and in 2027 for a potential launch. An update on the financial outlook for 2026 will be provided in connection with the publication of LEO Pharma’s H1 2026 Interim Report on 18 August 2026. J.P. Morgan Securities plc acted as financial advisors to LEO Pharma in this transaction and Latham Watkins LLP acted as legal advisors. About LEO Pharma LEO Pharma is a global leader in medical dermatology. We deliver innovative solutions for skin health, building on a century of experience with breakthrough medicines in healthcare. We are committed to making a fundamental difference in people’s lives, and our broad portfolio of treatments serves close to 100 million patients in over 70 countries annually. LEO Pharma is co-owned by majority shareholder the LEO Foundation and, since 2021, Nordic Capital. Headquartered in Denmark, LEO Pharma has a team of 4,400 people worldwide. Together, we reach far beyond the skin. For more information, visit . About Tanabe Pharma Tanabe Pharma Corporation is a Japan-focused, innovation-driven pharmaceutical company guided by its mission, "Creating hope for all facing illness." Founded in 1678, the Company is one of Japan's oldest pharmaceutical companies and is committed to addressing unmet medical needs through R＆D, business development, and strategic partnerships with the aim of improving the lives of patients. For more information, visit Tanabe Pharma Corporation References: ClinicalTrials.gov . National Library of Medicine (U.S.). INcreased Sun Exposure Without Pain In Research Participants With EPP or XLP (INSPIRE). Identifier: NCT06144840. . Wensink D, et al. Liver involvement in patients with EPP. 2021 Balwani M. Erythropoietic Protoporphyria and X-Linked Protoporphyria: pathophysiology, genetics, clinical manifestations, and management. 2019 Tanabe Pharma Corporation. Tanabe Pharma Announces Positive Data from Phase 3 INSPIRE Study of Dersimelagon in EPP and XLP. Press release. March 30, 2026. Available at: Contacts LEO Pharma contacts: Investors: Christian Boas Ryom, Investor Relations +45 4494 5888 chsoe@leo-pharma.com or Christopher Broe Hansen +45 5355 3895 chbhn@leo-pharma.com Media: Jeppe Ilkjær, Global Media Relations +45 3050 2014 jeilk@leo-pharma.com