The effects of cholecalciferol and afamelanotide on vitamin D levels in erythropoietic protoporphyria: a multicentre cohort study.

BACKGROUND: Patients with erythropoietic protoporphyria experience lifelong painful photosensitivity resulting in a lack of sunlight exposure. Previous studies have shown that 47-63% of patients with EPP suffer from vitamin D deficiency and a high prevalence of osteoporosis. An effective treatment for EPP has been available since 2016: the α-melanocyte stimulating hormone analogue afamelanotide. So far, studies on vitamin D levels in EPP have only investigated patients who have not been treated with afamelanotide. OBJECTIVES: To investigate the effects of afamelanotide treatment on vitamin D levels in EPP. METHODS: A multicentre observational cohort study in adults with EPP from the Erasmus Medical Centre, the Netherlands, and the University Hospital Düsseldorf, Germany, was carried out. Routinely collected vitamin D levels between 2005 and 2021 were used for analysis. Patient exposure to cholecalciferol or afamelanotide was categorized into four treatment groups: untreated, cholecalciferol, afamelanotide and combined treatment. A linear mixed model for longitudinal data was applied to measure the effect of the treatment groups compared with the untreated groups on vitamin D levels. RESULTS: A total of 230 patients and 1774 vitamin D measurements were included. The prevalence of vitamin D deficiency and severe deficiency remained high despite afamelanotide treatment (< 50 nmol L-1 in 71.8% of patients and < 30 nmol L-1 in 48.1%, respectively). Afamelanotide treatment alone did not lead to a significant average increase in vitamin D levels [ß = 0.5, 95% confidence interval (CI) -3.2 to 4.2]. In contrast, cholecalciferol and combined therapy with afamelanotide led to a significant increase in vitamin D levels [ß = 11.6 (95% CI 7.2-15.9) and ß = 15.2 (95% CI 12.3-18.1), respectively]. CONCLUSIONS: Cholecalciferol remains essential for the treatment of vitamin D deficiency in EPP, irrespective of new treatment options like afamelanotide. Afamelanotide treatment did not affect vitamin D levels. We suggest that future guidelines include continuous monitoring of vitamin D and a prescription for cholecalciferol in all patients with EPP, including those treated with afamelanotide.

Erythropoietic protoporphyria (EPP) is a rare inherited condition. People with EPP experience severe pain after their skin has been exposed to sunlight. To avoid this severe pain, people with EPP avoid going out in the sun by limiting outdoor activities or by wearing protective clothing. As sunlight is needed for our skin to produce vitamin D, approximately half of people with EPP in Europe do not have enough of it. In 2016, a new treatment called afamelanotide (SCENESSE®) became available, which allows people with EPP to go outside and expose themselves to sunlight longer without pain. In this study, we looked at how afamelanotide and vitamin D supplements affect vitamin D levels in people with EPP. We included information from patients treated in Rotterdam in the Netherlands and Düsseldorf in Germany and analysed levels of vitamin D in their blood. We also examined electronic patient files and collected questionnaires on the use of vitamin D supplements. In total, information from 230 patients was included. We found that afamelanotide alone did not raise vitamin D levels, but in combination with vitamin D supplements, vitamin D levels did go up. Even though afamelanotide is now available, our findings suggest that people with EPP may need more time to adapt to an outdoor lifestyle, after being conditioned to avoid sunlight since their childhood. Overall, our study demonstrates that vitamin D supplements remain crucial for people with EPP, with or without afamelanotide treatment.

Erythropoietic protoporphyrias: Pathogenesis, diagnosis and management.

The erythropoietic protoporphyrias consist of three ultra-rare genetic disorders of the erythroid heme biosynthesis, including erythropoietic protoporphyria (EPP1), X-linked protoporphyria (XLEPP) and CLPX-protoporphyria (EPP2), which all lead to the accumulation of protoporphyrin IX (PPIX) in erythrocytes. Affected patients usually present from early childhood with episodes of severe phototoxic pain in the skin exposed to visible light. The quantification of PPIX in erythrocytes with a metal-free PPIX ≥3 times the upper limit of normal confirms the diagnosis. Protoporphyria-related complications include liver failure, gallstones, mild anaemia and vitamin D deficiency with reduced bone mineral density. The management is focused on preventing phototoxic reactions and treating the complications. Vitamin D should be supplemented, and DEXA scans in adults should be considered. In EPP1, even in cases of biochemically determined iron deficiency, supplementation of iron may stimulate PPIX production, resulting in an increase in photosensitivity and the risk of cholestatic liver disease. However, for patients with XLEPP, iron supplementation can reduce PPIX levels, phototoxicity and liver damage. Because of its rarity, there is little data on the management of EPP-related liver disease. As a first measure, any hepatotoxins should be eliminated. Depending on the severity of the liver disease, phlebotomies, exchange transfusions and ultimately liver transplantation with subsequent haematopoietic stem cell transplantation (HSCT) are therapeutic options, whereby multidisciplinary management including porphyria experts is mandatory. Afamelanotide, an alpha-melanocyte-stimulating hormone analogue, is currently the only approved specific treatment that increases pain-free sunlight exposure and quality of life.

Quality of life in children with erythropoietic protoporphyria: a case-control study.

Erythropoietic protoporphyria (EPP) is an inherited metabolic disease that causes painful phototoxic reactions, starting in childhood. Studies have shown a reduced quality of life (QoL) in adults with EPP, however, data on children with the disease are lacking. Since treatment for EPP is currently not registered for children, knowledge about their QoL is of crucial importance. In this prospective, case-control study, we included children from the Netherlands and Belgium diagnosed with EPP and matched to healthy controls. Previously collected EPP quality of life (EPP-QoL) data from matched adults with EPP were used. QoL scores, utilizing the Pediatric Quality of Life Inventory (PedsQL) and the disease-specific EPP-QoL, were collected. Scores range from 0 to 100, with higher scores indicating a higher QoL. Non-parametric tests were used to compare groups. A total of 15 cases, 13 matched healthy control children, and 15 matched adults with EPP were included. Children with EPP exhibited lower median scores in the PedsQL in both physical (cases: 87.5 (interquartile range [IQR] 77.7-96.1), controls: 99.2 [IQR 94.9-100.0], p = 0.03) and social (cases: 77.5 [IQR 69.4-86.3], controls: 97.5 [IQR 78.8-100.0], p = 0.04) domains compared to healthy children, although these differences were not statistically significant after correcting for multiple testing. The overall median EPP-QoL score for children was similar to adults with EPP (children: 44.4 [IQR 25.0-54.2], adults: 45.8 [IQR 25.7-68.1], p = 0.68). However, within the EPP-QoL subdomain on QoL, children were found to have significantly lower median scores (children: 16.7 [IQR 0.0-33.3], adults: 33.3 [IQR 33.3-62.5], p < 0.01). In conclusion, children with EPP experience a reduced QoL compared to both healthy children and adults with EPP. Ensuring treatment availability for this patient group is crucial for improving their QoL. We advocate the inclusion of children in safety and efficacy studies, to ensure availability of treatment in the future.