Ethical, Legal and Regulatory Issues of Paediatric Translational Research. Call for an Adequate Model of Governance.

The lack of paediatric medicines, including innovative and advanced ones, is a long-lasting and well-known problem at European and international levels. Despite the existing legal frameworks and incentives, children remain deprived of many kinds of therapy because of challenges faced in appropriately study and tailoring medicinal and other products for them. In this context, the necessity to foster paediatric research addressing unsolved and uncovered issues within a 'translational approach' has appeared. This article, after having clarified the concept of translational research in the perspective of the establishment of a European paediatric research infrastructure (RI), will identify and point out ethical, legal and regulatory issues particularly relevant in a children's rights perspective. It concludes asking for the setting up of an adequate model of governance within a future RI, including adequate and independent ethical oversight and a pluridisciplinary common service dealing with ethical, legal and societal issues relevant for children.

CoCas9 is a compact nuclease from the human microbiome for efficient and precise genome editing.

The expansion of the CRISPR-Cas toolbox is highly needed to accelerate the development of therapies for genetic diseases. Here, through the interrogation of a massively expanded repository of metagenome-assembled genomes, mostly from human microbiomes, we uncover a large variety (n = 17,173) of type II CRISPR-Cas loci. Among these we identify CoCas9, a strongly active and high-fidelity nuclease with reduced molecular size (1004 amino acids) isolated from an uncultivated Collinsella species. CoCas9 is efficiently co-delivered with its sgRNA through adeno associated viral (AAV) vectors, obtaining efficient in vivo editing in the mouse retina. With this study we uncover a collection of previously uncharacterized Cas9 nucleases, including CoCas9, which enriches the genome editing toolbox.

A DNA base-specific sequence interposed between CRX and NRL contributes to RHODOPSIN expression.

Gene expression emerges from DNA sequences through the interaction of transcription factors (TFs) with DNA cis-regulatory sequences. In eukaryotes, TFs bind to transcription factor binding sites (TFBSs) with differential affinities, enabling cell-specific gene expression. In this view, DNA enables TF binding along a continuum ranging from low to high affinity depending on its sequence composition; however, it is not known whether evolution has entailed a further level of entanglement between DNA-protein interaction. Here we found that the composition and length (22 bp) of the DNA sequence interposed between the CRX and NRL retinal TFs in the proximal promoter of RHODOPSIN (RHO) largely controls the expression levels of RHO. Mutagenesis of CRX-NRL DNA linking sequences (here termed "DNA-linker") results in uncorrelated gene expression variation. In contrast, mutual exchange of naturally occurring divergent human and mouse Rho cis-regulatory elements conferred similar yet species-specific Rho expression levels. Two orthogonal DNA-binding proteins targeted to the DNA-linker either activate or repress the expression of Rho depending on the DNA-linker orientation relative to the CRX and NRL binding sites. These results argue that, in this instance, DNA itself contributes to CRX and NRL activities through a code based on specific base sequences of a defined length, ultimately determining optimal RHO expression levels.

Children's Preferences for Oral Dosage Forms and Their Involvement in Formulation Research via EPTRI (European Paediatric Translational Research Infrastructure).

The paucity of evidence-based data on formulation characteristics preferred by the children is known to limit the design of tailored paediatric dosage forms. The European Paediatric Translational Research Infrastructure (EPTRI) commissioned a study to evaluate children's dosage forms perceived preferences in some European countries and explore the feasibility of using the young persons advisory groups (YPAGs) to involve children in formulation research. An online, age-adapted survey was developed and translated into six languages. The survey link was disseminated across seven European countries: Albania, Italy, the Netherlands, and Dutch-speaking part of Belgium, Romania, Spain, and the United Kingdom. Respondents' (n = 1172) perceived preferences for oral dosage forms primarily differed based on age, health status, and experience. Conventional dosage forms, i.e., liquid (35%), tablets (19%), and capsules (14%), were the most selected. Liquid was widely selected by children less than 12 years and by those healthy and taking medicines rarely. Monolithic solid forms were mostly chosen by adolescents and by children with a chronic disease taking medicines frequently. There was a clear lack of familiarity with more novel dosage forms (e.g., orodispersible films and granules). Noteworthy, granules were not appreciated, particularly by adolescents (52.8%). To rationalise the creation of paediatric formulations, it is important to involve children as active stakeholders and to apply tools assessing children's perspectives on medicines to inform acceptable dosage form development from the start.

Inclusion of a degron reduces levelsof undesired inteins after AAV-mediated proteintrans-splicing in the retina.

Split intein-mediated protein trans-splicing expands AAV transfer capacity, thus overcoming the limited AAV cargo. However, non-mammalian inteins persist as trans-splicing by-products, and this could raise safety concerns for AAV intein clinical applications. In this study, we tested the ability of several degrons to selectively decrease levels of inteins after protein trans-splicing and found that a version of E. coli dihydrofolate reductase, which we have shortened to better fit into the AAV vector, is the most effective. We show that subretinal administration of AAV intein armed with this short degron is both safe and effective in a mouse model of Stargardt disease (STGD1), which is the most common form of inherited macular degeneration in humans. This supports the use of optimized AAV intein for gene therapy of both STGD1 and other conditions that require transfer of large genes.

Paediatric clinical research in Europe: an insight on experts' needs and perspectives.

PedCRIN is a Horizon 2020 project aimed to develop a paediatric component of ECRIN (European Clinical Research Infrastructure Network) including tools supporting the conduct of neonatal and paediatric trials. A structured, cross-sectional, closed-ended questionnaire was electronically administered from April to May 2017 to stakeholders involved in paediatric clinical research to capture their needs to receive infrastructural support to cover specific research gaps. The questionnaire included 6 headings and 29 subheadings. Each item was evaluated using a Likert-scale. 147 questionnaires were returned (response rate of 24.6%). The application of innovative study design and the preparation of protocols for paediatric interventional clinical trials had the highest frequency of high need for support (123 and 117 respondents, respectively). Similarly, the identification and applications to relevant calls for funding was acknowledged as an area in which support is needed (123 respondents declaring high need). In 14 out of 29 activities, need for support was significantly higher in the respondents not being part of a Paediatric Research Network or Consortium (especially for regulatory expertise, pharmacovigilance and GCP training). Conclusions: These results document that the achievement of PedCRIN objectives would greatly advantage the paediatric research community.

Medical Device Development for Children and Young People-Reviewing the Challenges and Opportunities.

Development of specific medical devices (MDs) is required to meet the healthcare needs of children and young people (CYP). In this context, MD development should address changes in growth and psychosocial maturation, physiology, and pathophysiology, and avoid inappropriate repurposing of adult technologies. Underpinning the development of MD for CYP is the need to ensure MD safety and effectiveness through pediatric MD-specific regulations. Contrary to current perceptions of limited market potential, the global pediatric healthcare market is expected to generate around USD 15,984 million by 2025. There are 1.8 billion young people in the world today; 40% of the global population is under 24, creating significant future healthcare market opportunities. This review highlights a number of technology areas that have led to successful pediatric MD, including 3D printing, advanced materials, drug delivery, and diagnostic imaging. To ensure the targeted development of MD for CYP, collaboration across multiple professional disciplines is required, facilitated by a platform to foster collaboration and drive innovation. The European Pediatric Translational Research Infrastructure (EPTRI) will be established as the European platform to support collaboration, including the life sciences industrial sector, to identify unmet needs in child health and support the development, adoption, and commercialization of pediatric MDs.

Intein-mediated protein trans-splicing expands adeno-associated virus transfer capacity in the retina.

Retinal gene therapy with adeno-associated viral (AAV) vectors holds promises for treating inherited and noninherited diseases of the eye. Although clinical data suggest that retinal gene therapy is safe and effective, delivery of large genes is hindered by the limited AAV cargo capacity. Protein trans-splicing mediated by split inteins is used by single-cell organisms to reconstitute proteins. Here, we show that delivery of multiple AAV vectors each encoding one of the fragments of target proteins flanked by short split inteins results in protein trans-splicing and full-length protein reconstitution in the retina of mice and pigs and in human retinal organoids. The reconstitution of large therapeutic proteins using this approach improved the phenotype of two mouse models of inherited retinal diseases. Our data support the use of split intein-mediated protein trans-splicing in combination with AAV subretinal delivery for gene therapy of inherited blindness due to mutations in large genes.

Investigating the roles and training of paediatric research nurses working across Europe: a questionnaire-based survey.

BACKGROUND: The key role played by research nurses in coordinating clinical trials in a paediatric setting has developed in line with increasing complexities of trial design. A questionnaire-based survey was conducted to investigate the training of research nurses involved in paediatric trials across Europe, to identify potential training needs and compare roles across specialties and countries. METHODS: A structured, cross-sectional questionnaire survey was used, with the aim of describing and quantifying research nurse experiences. The questionnaire was designed to cover four main areas of interest: demographics, training, clinical trial experience and research nurse roles/activities. RESULTS: The questionnaire was completed by 341 respondents across 45 different specialties in 20 European countries. A higher percentage of research nurses within 3 years of taking up post were dissatisfied with the level of training received (16%), as compared with those in post for 3-6 years (8%) and >6 years (6%). There was a trend towards a higher percentage of respondents receiving self-funded training in mainland Europe, with reported values of 15%-20%, as compared with <5% in the UK and Ireland. Only 3% of research nurses prescribed investigational medicinal products in a clinical trial setting, with contrasting roles observed between countries. CONCLUSIONS: While high levels of training satisfaction were observed, 67% of respondents felt they would benefit from additional training in line with frequently changing practices. Currently, low levels of nurse prescribing are observed in a paediatric clinical trial setting across Europe. Appropriate research nurse training programmes should be promoted through national networks across Europe.

Rhodopsin targeted transcriptional silencing by DNA-binding.

Transcription factors (TFs) operate by the combined activity of their DNA-binding domains (DBDs) and effector domains (EDs) enabling the coordination of gene expression on a genomic scale. Here we show that in vivo delivery of an engineered DNA-binding protein uncoupled from the repressor domain can produce efficient and gene-specific transcriptional silencing. To interfere with RHODOPSIN (RHO) gain-of-function mutations we engineered the ZF6-DNA-binding protein (ZF6-DB) that targets 20 base pairs (bp) of a RHOcis-regulatory element (CRE) and demonstrate Rho specific transcriptional silencing upon adeno-associated viral (AAV) vector-mediated expression in photoreceptors. The data show that the 20 bp-long genomic DNA sequence is necessary for RHO expression and that photoreceptor delivery of the corresponding cognate synthetic trans-acting factor ZF6-DB without the intrinsic transcriptional repression properties of the canonical ED blocks Rho expression with negligible genome-wide transcript perturbations. The data support DNA-binding-mediated silencing as a novel mode to treat gain-of-function mutations.