? 2021 Association Mieux Prescrire. All rights reserved.? Erythropoietic protoporphyria is a rare genetic disease in which an enzyme deficiency leads to accumulation of protoporphyrin. Protoporphyrin absorbs light energy, inducing phototoxic skin reactions with sometimes severe symptoms (itching, pain, redness and oedema) when the patient is exposed to light. For some patients, the severity of the symptoms and the sometimes drastic preventive measures required (e.g. strictly limiting light exposure and wearing protective clothing) have a major impact on everyday quality of life. As of 2021, there is no known curative treatment for erythropoietic protoporphyria. ? Afamelanotide (Scenesse, Clinuvel) is a peptide analogue of melanocortin, hormone which stimulates the synthesis of eumelanin (a photoprotective pigment) in the skin. ? A double-blind randomised trial compared afamelanotide versus placebo in 93 adults. Over the 6 months of the trial, taking into account only the days when patients had no pain, the median duration of sun exposure was about 69 hours in the afamelanotide group versus 41 hours in the placebo group (p=0.04). Expressed in terms of the gain in daily exposure, the difference between the groups was minimal, with a median duration of 26 minutes spent in direct sunlight for the afamelanotide group versus 18 minutes in the placebo group. There was no difference between the groups with respect to the frequency of phototoxic reactions or the severity of symptoms. ? The main adverse effects shown in the clinical trials were implantation site reactions, development of naevi and skin discolouration. Allergic reactions were also reported and a risk of skin cancer in the long term cannot be ruled out.
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