Dersimelagon (MT-7117)

Erythropoietic protoporphyria and X-linked protoporphyria are inherited disorders of heme biosynthesis in which protoporphyrin IX accumulates and is photoactivated by visible light near 400 nm, producing severe non-blistering phototoxic pain within minutes of sunlight exposure. Estimated incidence is two to five per 1,000,000, and reported prevalence ranges from 1 in 75,000 in the Netherlands to 1 in 200,000 in Wales; X-linked protoporphyria accounts for about 10% of cases in the United States. Photosensitivity begins in infancy or childhood, with a mean age at symptom onset of 4.4 years, and persists for life. Most patients tolerate less than 30 minutes of sun exposure. In a survey of 164 adults and 33 adolescents, symptoms hindered daily activities at least somewhat for 62.8% of adults and 87.9% of adolescents. Hepatic dysfunction occurs in 20% to 30% of individuals and 2% to 5% develop severe liver disease; in a United States longitudinal study of 322 participants, 8 (2.5%) had a liver transplant and 8 (2.5%) died, with at least half of deaths attributable to liver involvement. In a national claims analysis of 696 patients, mean all-cause costs were $71,714 per patient per year compared with $18,646 in matched comparators.