Tanabe Pharma America’s oral melanocortin-1 receptor (MC1R) agonist has met the primary endpoint in a Phase III trial in patients with erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP).
The INSPIRE study (NCT06144840) of dersimelagon met its primary endpoint of time to first prodromal symptoms, such as burning, tingling, itching, or stinging, associated with sunlight exposure.
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The study, which enrolled 165 patients with EPP and XLP, consisted of a 16-week double-blind, randomised treatment period, in which patients received either dersimelagon 200mg once daily or placebo. This has been followed by an ongoing, 36-week open-label extension period of active treatment.
Secondary endpoints are Global Impression of Change (PGIC) at week 16, the total number of sunlight-induced pain events defined as prodromal symptoms with pain rating of 1-10 on the Likert scale at week 16, and the total number of sunlight-induced non-prodrome, phototoxic reactions during the double-blind treatment period.
Dersimelagon demonstrated a favourable safety and tolerability profile, with most adverse events being mild or moderate in severity.
EPP and XLP are rare hereditary disorders of the heme biosynthetic pathway. Patients suffer severe pain in the skin upon exposure to sunlight and some forms of artificial light. It is estimated that approximately 1 in 75,000 to 1 in 200,000 individuals have EPP in the European population, though the prevalence in the US is not known.
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By GlobalDataBijan Nejadnik, Tanabe’s head of global development and regulatory affairs, said: “The limited treatment options for adults with EPP or XLP and lack of any approved treatments for adolescents have created a care deficit, forcing many to endure severe life disruptions as they rely only on sun protection or avoidance. The positive topline results from the INSPIRE study represent key data that will guide our research for the porphyria community.”
Dersimelagon received Fast Track Designation from the US Food and Drug Administration (FDA) in June 2018 and was granted Orphan Drug Designation in June 2020.
Tanabe Pharma America, a subsidiary of the Tanabe Pharma Corporation, is not the only company developing drugs for EPP and XLP. In January 2025, Disc Medicine raised $225.5m to run a Phase III trial of its drug bitopertin in EPP and XLR (NCT06910358).
Tanabe Pharma’s earlier success, however, could provide the company with a first-to-market advantage.
