Analysis of the functional consequences of targeted exon deletion in COL7A1 reveals prospects for dystrophic epidermolysis bullosa therapy

Genetically evoked deficiency of collagen VII causes dystrophic epidermolysis bullosa (DEB)-a debilitating disease characterized by chronic skin fragility and progressive fibrosis. Removal of exons carrying frame-disrupting mutations can reinstate protein expression in genetic diseases. The therapeutic potential of this approach is critically dependent on gene, protein, and disease intrinsic factors. Naturally occurring exon skipping in COL7A1, translating collagen VII, suggests that skipping of exons containing disease-causing mutations may be feasible for the treatment of DEB. However, despite a primarily in-frame arrangement of exons in the COL7A1 gene, no general conclusion of the aptitude of exon skipping for DEB can be drawn, since regulation of collagen VII functionality is complex involving folding, intra-and intermolecular interactions. To directly address this, we deleted two conceptually important exons located at both ends of COL7A1, exon 13, containing recurrent mutations, and exon 105, predicted to impact folding. The resulting recombinantly expressed proteins showed conserved functionality in biochemical and in vitro assays. Injected into DEB mice, the proteins promoted skin stability. By demonstrating functionality of internally deleted collagen VII variants, our study provides support of targeted exon deletion or skipping as a potential therapy to treat a large number of individuals with DEB

Strengthening regulatory science in academia:STARS, an EU initiative to bridge the translational gap

Truly disruptive medicine innovation and new treatment paradigms tend to start in non-commercial research institutions. However, the lack of mutual understanding between medicine developers and regulators when it comes to medicine development significantly delays or even prevents the access of patients to these innovations. Here, we outline what regulatory-related barriers hamper the translational development of novel products or new treatment paradigms initiated in academia, and propose key steps towards improved regulatory dialogue among academia, funding bodies and regulatory authorities. Moreover, we briefly describe how the STARS (Strengthening Training of Academia in Regulatory Science) project aims to reach out to medicine innovators in academia to bridge the regulatory knowledge gap and enhance this dialogue to facilitate the implementation of academic research findings in clinical practice

Natural Exon Skipping Sets the Stage for Exon Skipping as Therapy for Dystrophic Epidermolysis Bullosa

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Mechanisms of Natural Gene Therapy in Dystrophic Epidermolysis Bullosa

Item does not contain fulltextRevertant mosaicism has been reported in several inherited diseases, including the genetic skin fragility disorder epidermolysis bullosa (EB). Here, we describe the largest cohort of seven patients with revertant mosaicism and dystrophic EB (DEB), associated with mutations in the COL7A1 gene, and determine the underlying molecular mechanisms. We show that revertant mosaicism occurs both in autosomal dominantly and recessively inherited DEB. We found that null mutations resulting in complete loss of collagen VII and severe disease, as well as missense or splice-site mutations associated with some preserved collagen VII function and a milder phenotype, were corrected by revertant mosaicism. The mutation, subtype, and severity of the disease are thus not decisive for the presence of revertant mosaicism. Although collagen VII is synthesized and secreted by both keratinocytes and fibroblasts, evidence for reversion was only found in keratinocytes. The reversion mechanisms included back mutations/mitotic recombinations in 70% of the cases and second-site mutations affecting splicing in 30%. We conclude that revertant mosaicism is more common than previously assumed in patients with DEB, and our findings will have implications for future therapeutic strategies using the patient's naturally corrected cells as a source for cell-based therapies

Murine type VII collagen distorts outcome in human skin graft mouse model for dystrophic epidermolysis bullosa

Human skin graft mouse models are widely used to investigate and develop therapeutic strategies for the severe generalized form of recessive dystrophic epidermolysis bullosa (RDEB), which is caused by bi-allelic null mutations in COL7A1 and the complete absence of type VII collagen (C7). Most therapeutic approaches are focused on reintroducing C7. Therefore, C7 and anchoring fibrils are widely used as readouts in therapeutic research with skin graft models. In this study, we investigated the expression pattern of human and murine C7 in a grafting model, in which human skin is reconstituted out of in vitro cultured keratinocytes and fibroblasts. The model revealed that murine C7 was deposited in both human healthy control and RDEB skin grafts. Moreover, we found that murine C7 is able to form anchoring fibrils in human grafts. Therefore, we advocate the use of human-specific antibodies when assessing the reintroduction of C7 using RDEB skin graft mouse models. This article is protected by copyright. All rights reserved

Postapproval trials versus patient registries:comparability of advanced melanoma patients with brain metastases

Postapproval trials and patient registries have their pros and cons in the generation of postapproval data. No direct comparison between clinical outcomes of these data sources currently exists for advanced melanoma patients. We aimed to investigate whether a patient registry can complement or even replace postapproval trials. Postapproval single-arm clinical trial data from the Medicines Evaluation Board and real-world data from the Dutch Melanoma Treatment Registry were used. The study population consisted of advanced melanoma patients with brain metastases treated with targeted therapies (BRAF- or BRAF-MEK inhibitors) in the first line. A Cox hazard regression model and a propensity score matching (PSM) model were used to compare the two patient populations. Compared to patients treated in postapproval trials (n = 467), real-world patients (n = 602) had significantly higher age, higher ECOG performance status, more often ≥3 organ involvement and more symptomatic brain metastases. Lactate dehydrogenase levels were similar between both groups. The unadjusted median overall survival (mOS) in postapproval clinical trial patients was 8.7 (95% CI, 8.1-10.4) months compared to 7.2 (95% CI, 6.5-7.7) months (P < 0.01) in real-world patients. With the Cox hazard regression model, survival was adjusted for prognostic factors, which led to a statistically insignificant difference in mOS for trial and real-world patients of 8.7 (95% CI, 7.9-10.4) months compared to 7.3 (95% CI, 6.3-7.9) months, respectively. The PSM model resulted in 310 matched patients with similar survival (P = 0.9). Clinical outcomes of both data sources were similar. Registries could be a complementary data source to postapproval clinical trials to establish information on clinical outcomes in specific subpopulations

Postapproval trials versus patient registries: comparability of advanced melanoma patients with brain metastases

Postapproval trials and patient registries have their pros and cons in the generation of postapproval data. No direct comparison between clinical outcomes of these data sources currently exists for advanced melanoma patients. We aimed to investigate whether a patient registry can complement or even replace postapproval trials. Postapproval single-arm clinical trial data from the Medicines Evaluation Board and real-world data from the Dutch Melanoma Treatment Registry were used. The study population consisted of advanced melanoma patients with brain metastases treated with targeted therapies (BRAF- or BRAF-MEK inhibitors) in the first line. A Cox hazard regression model and a propensity score matching (PSM) model were used to compare the two patient populations. Compared to patients treated in postapproval trials (n = 467), real-world patients (n = 602) had significantly higher age, higher ECOG performance status, more often ≥3 organ involvement and more symptomatic brain metastases. Lactate dehydrogenase levels were similar between both groups. The unadjusted median overall survival (mOS) in postapproval clinical trial patients was 8.7 (95% CI, 8.1-10.4) months compared to 7.2 (95% CI, 6.5-7.7) months (P < 0.01) in real-world patients. With the Cox hazard regression model, survival was adjusted for prognostic factors, which led to a statistically insignificant difference in mOS for trial and real-world patients of 8.7 (95% CI, 7.9-10.4) months compared to 7.3 (95% CI, 6.3-7.9) months, respectively. The PSM model resulted in 310 matched patients with similar survival (P = 0.9). Clinical outcomes of both data sources were similar. Registries could be a complem

Topical Gentamicin for the Treatment of Genetic Skin Diseases

Clinical application of topical gentamicin is a worthwhile option to investigate further for Nagashima-type palmoplantar keratosis and other genetic skin diseases caused by nonsense mutations. It is especially interesting to study gentamicin 1B because it may be more efficacious than other gentamicin components. Topical gentamicin has an acceptable safety profile, although prospective tracking of antibiotic resistance is warranted