The U.S. Food and Drug Administration (FDA) granted approval to Scenesse (afamelanotide) to increase pain-free light exposure in adult patients with a history of phototoxic reactions (damage to skin) from erythropoietic protoporphyria (EPP). For patients who are suffering from EPP, exposure to light may be extremely painful.
Erythropoietic protoporphyria (EPP) is a type of porphyria. Porphyrias are caused by an abnormality in the heme production process. Heme is essential in enabling our blood cells to carry oxygen and in breaking down chemical compounds in the liver. Erythropoietic protoporphyria is caused by pathogenic variants (mutations) in the FECH gene which lead to an impaired activity of ferrocheletase (FECH), an important enzyme in heme production. This results in the build-up of protoporphyrin in the bone marrow, red blood cells, blood plasma, skin, and eventually liver. Build up of protoporphyrin can cause extreme sensitivity to sunlight, liver damage, abdominal pain, gallstones, and enlargement of the spleen. Inheritance is autosomal recessive.
“With this new approval, there were no FDA-approved treatments to help erythropoietic protoporphyria patients increase their light exposure,” said Julie Beitz, MD, director of FDA’s Center for Drug Evaluation and Research Office of Drug Evaluation III in an FDA press release. “Today’s approval is one example of the FDA’s ongoing commitment to encourage industry innovation of therapies to treat rare diseases, and work with drug developers to make promising new therapies available to patients as safely and efficiently as possible.”
Scenesse (afamelanotide) is a melanocortin-1 receptor (MC1-R) agonist and increases the production of eumelanin in the skin independent of exposure to sunlight or artificial light sources. It is an implant that is administered subcutaneously.
The efficacy of Scenesse was established in two group clinical trials with patients with EPP who received Scenesse or placebo form of the implant subcutaneously every two months. The first clinical trial enrolled 93 subjects, of whom 48 received Scenesse, and were followed for 180 days. The primary endpoint was the total number of hours over 180 days spent in direct sunlight between 10 a.m. and 6 p.m. on days with no pain. The median total number of hours over 180 days spent in direct sunlight between 10 a.m. and 6 p.m. on days with no pain was 64 hours for patients receiving Scenesse and 41 hours for patients taking placebo.
The second clinical trial enrolled 74 patients, of whom 38 received Scenesse, and were followed for 270 days. The primary endpoint was the total number of hours over 270 days spent outdoors between 10 am and 3 pm on days with no pain for which “most of the day” was spent in direct sunlight. 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 over 270 days spent outdoors between 10 am and 3 pm on days with no pain for which “most of the day” was spent in direct sunlight was six hours for patients receiving Scenesse and 0.75 hours for patients receiving placebo.
Scenesse’s most common side effects are implant site reaction, nausea, oropharyngeal (part of the throat just behind the mouth, where the oral cavity starts) pain, cough, fatigue, skin hyperpigmentation, dizziness, melanocytic nevus (moles), respiratory tract infection, somnolence (feeling drowsy), non-acute porphyria (build-up of normally occurring molecules created during heme production) and skin irritation.