FDA approves drug for rare condition that triggers intense pain from light exposure
Five years after EU regulators approved a therapy to treat a rare inherited metabolic condition that causes extreme sensitivity to light, the FDA has endorsed the treatment — marking the first-ever approval for patients with erythropoietic protoporphyria (EPP) in the United States.
The therapy, which is administered via an implant inserted subcutaneously, was developed by Australian drug maker Clinuvel Pharmaceuticals and is sold as Scenesse.
In patients with EPP, the activity of ferrochelatase — an enzyme involved in the production of a key component in hemoglobin — is compromised. Reduced ferrochelatase activity causes the accumulation of protoporphyrin IX (PPIX) — and light exposure on the skin can react with PPIX, sparking intense pain, redness and thickening.
Scenesse, known chemically as afamelanotide, binds with the melanocortin-1 receptor on the surface of melanocyte cells found in the epidermis of the skin. This triggers a cascade of reactions that result in the melanocyte favoring the production of eumelanin (black/brown) over pheomelanin (red/yellow). The production of eumelanin in the skin independent of exposure to sunlight or artificial light sources offers the patient the ability to cope with the molecular damage caused by light.
In January, STAT profiled a Connecticut woman who compared the pain she felt from light exposure to the experience of having boiling oil poured on her hands and knees. Only around 600 Americans suffer from EPP. Switzerland and Italy had Clinuvel agree to pay 80% of the drug’s cost before allowing it, according to STAT.
“We are determining our pricing strategy (in the United States) but our approach is going to be far more transparent and fair than many of our peers. For this we refer you to our approach to pricing in Europe,” a Clinuvel spokesperson told Endpoints News.
Scenesse is priced in Europe at €14,101 per injectable implant, or €56,404 per patient based on four injectable implants per annum (excluding local taxes), the spokesperson added.
The US approval for Scenesse was based on twin placebo-controlled clinical trials. In the first 93-patient trial, 48 subjects were given Scenesse, while the rest were on placebo. After 180 days of exposure to direct sunlight between 10 am and 6 pm, patients on the therapy were pain-free for a median 64 hours, versus 41 hours for those in the placebo arm.
In the other 74-patient study, 38 received Scenesse, while the rest got placebo. Patients were followed for 270 days which they spent outdoors between 10 am and 3 pm and were assessed for pain levels — although the analysis did not include sun exposure on days patients reported spending time in a combination of both direct sunlight and shade. The median total number of hours under these conditions in which patients felt ‘no pain’ was six hours for patients receiving Scenesse and 0.75 hours for patients receiving placebo.
Clinuvel formed in 1987 after researchers started working on the idea of synthesizing human hormones to protect the skin.