Clinical Research Directory

Impact of Optimized Recruitment and Follow-up of Patients With Pseudoxanthoma Elasticum (PXE)

Pseudoxanthoma elasticum (PXE) is a rare genetic disorder characterized by ectopic calcifications in the skin, retina and arterial walls. Angers University Hospital is the national rare disease reference center (CRMR) for PXE. Although PXE is hereditary, its main clinical manifestations (unsightly skin lesions, intermittent arterial claudication, stroke, retinal bleeding and blindness) are delayed and slowly progress over the course of a lifetime. They are rarely life-threatening but have a major functional impact. To date, management of PXE is purely preventive and symptomatic. Three successive "states" can be individualized during PXE course, corresponding to three very different patient profiles in terms of age, clinical manifestations, occurrence of complications and their treatment. PXE is essentially a severe disease in adults in the second half of life. This contrasts with the presence of many patients seen for their follow-up at school age or in employment, and at the age of children. It is therefore necessary to optimize the recruitment of PXE patients and to rethink their follow-up by the CRMR. The investigators hypothesize that the implementation of alternating treatment paths, better adapted to each of the three patient profiles, including multidisciplinary teleconsultations, will not only increase the number of patients monitored by the CRMR and benefit from referral care, but also to optimize care, for greater patient satisfaction, their local doctors and the CRMR team.

The ENERGY Study: Evaluation of Safety and Tolerability of INZ-701 in Infants With ENPP1 Deficiency or ABCC6 Deficiency

The primary purpose of Study INZ701-104 (the ENERGY study) is to assess the safety and tolerability of INZ-701 in infants with ENPP1 Deficiency or with ABCC6 Deficiency.

Purinergic Compounds in Pseudoxanthoma Elasticum

Pseudoxanthoma elasticum (PXE) is a rare genetic disorder, transmitted as an autosomal recessive trait, affecting approximately 1 in 50,000 people, predominantly women. It is characterised by progressive calcification of tissues rich in elastic fibres, particularly the skin, retina and arteries. It often begins in young adults and can eventually lead to central blindness, peripheral artery disease, strokes, tendon pain, recurrent kidney stones and visible skin changes. The diagnosis is based on clinical examination (skin papules, angioid streaks) and can be confirmed by biopsy or genotyping of the ABCC6 gene, whose mutation leads to extracellular ATP deficiency. This deficiency reduces the production of pyrophosphate (PPi), a natural inhibitor of calcification, thus promoting abnormal calcium deposits in tissues. To date, there is no curative treatment, but clinical trials are evaluating oral administration of PPi, with encouraging results. The role of purinergic metabolism is increasingly being explored in PXE. The cascade of conversion of ATP to adenosine (ADO) via ectonucleotidase pyrophosphatase 1 (ENPP1) and 5' ectonucleotidase (NT5E) indirectly regulates the activity of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme that degrades PPi. An imbalance in this cascade could aggravate calcifications. The joint measurement of PPi, ADO and these enzymes, which has recently become possible, could not only refine our understanding of the disease, but also pave the way for new therapeutic strategies.

CHOPXE - Analysis of Choriocapillaris Flow Deficits in Patients With Pseudoxanthoma Elasticum

This observational study sets out to compare choriocapillaris flow deficits between healthy control subjects and patients with pseudoxanthoma elasticum. Pseudoxanthoma elasticum (PXE) is a rare, incurable hereditary disease caused by genetic mutations. The condition is characterised by excessive tissue mineralisation, which can result in a range of dermatological, vascular, and ophthalmological complications. Among these complications is the potential for visual impairment. The management of this condition is focused on the treatment of its complications. Degeneration of the retina and the choroid (the layer responsible for ensuring its vascularisation) occurs in the eye, resulting in premature degeneration. We would like to study the premature alteration of these structures, which could subsequently be used as an objective marker of the evolution of pseudoxanthoma elasticum.

Progression Assessment of PXE-associated Alterations

This monocentric clinical observational study at the University Eye Hospital Bonn investigates the natural history and structural consequences of a diseased Bruch's membrane (BrM) in Pseudoxanthoma elasticum (PXE). The study includes four main objectives: 1. Direct Bruch's Membrane Alterations: Longitudinal analysis of BrM reflectivity using high-resolution OCT to assess correlations with disease progression 2. Choriocapillaris Flow Deficits: Evaluation of choriocapillaris (CC) perfusion in relation to BrM calcification, aiming to clarify whether CC deficits precede or result from BrM changes 3. Retinal Atrophy Progression: Monitoring the development and expansion of retinal atrophic areas over two years, including correlations with specific features like reticular pseudodrusen and hyperreflective spots 4. Genotype-Phenotype Correlation: Analysis of different ABCC6 gene mutations to identify correlations with imaging features and disease severity, potentially guiding future personalized therapeutic strategies The study will recruit 100 PXE patients and 100 controls, with data collection over 10 years. It involves non-invasive imaging and blood sampling. No direct benefit is expected for participants, but the findings may inform future clinical trials and improve patient counseling.

Progression Rate of Pseudoxanthoma Elasticum-associated Choroidal and Retinal Degeneration

This study aims to systematically assess the retest reliability and ability to detect a change of new visual function tests and ophthalmological imaging methods for observing the natural course of pseudoxanthoma elasticum (PXE).

ADAPT Study: Long-term Safety Study of INZ-701 in Patients With ENPP1 Deficiency and ABCC6 Deficiency

The purpose of this study (Study INZ701-304 \[ADAPT\]) is to assess the long-term safety of INZ-701 in patients with ENPP1 Deficiency or ABCC6 Deficiency who have received INZ-701 in an existing clinical study and choose to continue dosing for the potential treatment of their condition.

PPI Supplementation to Fight ECtopIc Calcification in PXE

Pseudoxanthoma elasticum (PXE) is a rare inherited metabolic disorder (OMIM 264800, frequency 1/25000) characterized by progressive ectopic calcification of connective tissues. PXE mainly affects the skin (inesthetic papules and plaques in the skin folds), the retina (central blindness), the vasculature (peripheral arterial occlusive disease and stroke) and the renal system (renal lithiasis) in adulthood. Although rarely, early lethal forms have been reported. This chronic and highly disabling condition results from a loss of function of the gene encoding for the ABCC6 membrane transporter primarily expressed in the hepatocytes and renal tubular cells. Recently, it has been reported that PXE was characterized by a 50-60% decrease in the plasma level of inorganic pyrophosphate (PPi), a major physiological anti-calcifying factor. PXE is an incurable disease which therapeutic options are limited to symptomatic treatments to stem the devastating effect of the ectopic calcifications. Recently, encouraging proof of concept studies with animals PXE models and healthy volunteers have shown that, contrary to what was initially reported and thought, the oral administration of PPi salts are able to increase PPi plasma levels, opening up new therapeutic perspectives in PXE. Therefore, we propose to perform the first Phase II randomized controlled trial (RCT) to evaluate the safety and efficacy of a daily and oral administration of PPi salts against placebo in PXE patients.

The Prevention of Systemic Ectopic Mineralization in Pseudoxanthoma Elasticum

The goal of this randomized clinical trial is to assess the effect of etidronate on ectopic calcification in relatively young patients with Pseudoxanthoma elasticum. The main question it aims to answer are: What is the difference in the arterial calcification scores in the legs and the carotid syphon measured on low-dose CT scan after 24 months of treatment compared to baseline between etidronate and placebo. Participants will be asked to do take etidronate or placebo for 24 months.