Patient Centricity: Design and Conduct of Clinical Trials in Orphan Diseases: Third of Three Sets of Expanded Proceedings from the 2020 ISCTM Autumn Conference on Pediatric Drug Development.

This article expands on a session, titled "Patient Centricity: Design and Conduct of Clinical Trials in Orphan Diseases," that was presented as part of a two-day meeting on Pediatric Drug Development at the International Society for Central Nervous System (CNS) Clinical Trials and Methodology (ISCTM) Autumn Conference in Boston, Massachusetts, in October 2020. Speakers from various areas of pediatric drug development addressed a variety of implications of including children in drug development programs, including implications for rare/orphan diseases. The speakers have written summaries of their talks. The session's lead Chair was Dr. Joan Busner, who wrote introductory and closing comments. Dr. Simon Day, regulatory consultant, outlined some of the past mistakes that have plagued trials that did not consult with patient groups in the early design phase. Dr. Atul Mahableshwarkar provided an industry perspective of a recent trial that benefited from the inclusion of patient input. Drs. Lucas Kempf and Maria Sheean provided regulatory input from the perspectives of the United States (US) Food and Drug Administration (FDA) and European Medicines Agency (EMA), respectively. Dr. Judith Dunn outlined a novel approach for assessing and rank ordering patient and clinician clinical meaningfulness and the disconnect that may occur. Dr. Busner provided closing comments, tied together the presented issues, and provided a synopsis of the lively discussion that followed the session. In addition to the speakers above, the discussion included two representatives from patient advocacy groups, as well as an additional speaker who described the challenges of conducting a pediatric trial in the US and European Union (EU), given the often competing regulatory requirements. This article should serve as an expert-informed reference to those interested and involved in CNS drug development programs that are aimed at children and rare diseases and seek to ensure a patient-centric approach.

Defining Satisfactory Methods of Treatment in Rare Diseases When Evaluating Significant Benefit-The EU Regulator's Perspective.

Since the implementation of the EU Orphan Regulation in 2000, the Committee for Orphan Medicinal Products at the European Medicines Agency has been evaluating the benefits of proposed orphan medicines vs. satisfactory treatment methods. This type of evaluation is foreseen in the Orphan Regulation as the orphan designation criterion called the "significant benefit." In this article, based on 20 years of experience, we provide a commentary explaining what is considered a satisfactory method of treatment in the context of the EU Orphan Regulation and for the purpose of the assessment of significant benefit. We discuss the challenges posed by continuously changing clinical practise, which is associated with the increasing number of treatment options, evolving nature of medicinal therapeutic indications and our understanding of them.

Regulatory Standards in Orphan Medicinal Product Designation in the EU.

Twenty years of orphan regulation in Europe have now elapsed, with almost 2,400 orphan designated medicinal products and more than 190 orphan products authorised in the EU. Alongside the evolution in understanding of rare diseases, considerable regulatory knowledge has also been accumulated regarding the level of evidence that would support inclusion of products into the framework. This article reviews publications and regulatory documents pertaining to orphan medicinal product designation in the EU and discusses the general expectations in submitted applications as reflected in the current regulatory practise. Important elements to recommend granting a European orphan designation are the key considerations of orphan condition, medical plausibility, seriousness, and prevalence, while significant benefit is also assessed when there are authorised medicinal products for the sought indication. This review attempts to clarify the specific concepts currently used in that regard and discusses how the available data can be used to justify the criteria for designation. Moving away from theoretical expectations or assumptions, it stresses that the applications have to be complemented with nosological and epidemiological justifications pertaining to the proposed condition, as well as relevant data in specific non-clinical in vivo models or in affected patients to support inclusion into the orphan scheme.

Nonclinical data supporting orphan medicinal product designations in the area of rare infectious diseases.

This review provides an overview of nonclinical in vivo models that can be used to support orphan designation in selected rare infectious diseases in Europe, with the aim to inform and stimulate the planning of nonclinical development in this area of often neglected diseases.

Neuregulin 3 promotes excitatory synapse formation on hippocampal interneurons.

Hippocampal GABAergic interneurons are crucial for cortical network function and have been implicated in psychiatric disorders. We show here that Neuregulin 3 (Nrg3), a relatively little investigated low-affinity ligand, is a functionally dominant interaction partner of ErbB4 in parvalbumin-positive (PV) interneurons. Nrg3 and ErbB4 are located pre- and postsynaptically, respectively, in excitatory synapses on PV interneurons in vivo Additionally, we show that ablation of Nrg3 results in a similar phenotype as the one described for ErbB4 ablation, including reduced excitatory synapse numbers on PV interneurons, altered short-term plasticity, and disinhibition of the hippocampal network. In culture, presynaptic Nrg3 increases excitatory synapse numbers on ErbB4+ interneurons and affects short-term plasticity. Nrg3 mutant neurons are poor donors of presynaptic terminals in the presence of competing neurons that produce recombinant Nrg3, and this bias requires postsynaptic ErbB4 but not ErbB4 kinase activity. Furthermore, when presented by non-neuronal cells, Nrg3 induces postsynaptic membrane specialization. Our data indicate that Nrg3 provides adhesive cues that facilitate excitatory neurons to synapse onto ErbB4+ interneurons.

Demonstrating significant benefit of orphan medicines: analysis of 15 years of experience in Europe.

In the European Union demonstration of 'significant benefit' is mandatory if satisfactory methods exist for a disease targeted by a new orphan medicinal product. Significant benefit is required at the time of orphan designation, when it can be supported by preclinical studies, and at the time of marketing authorization, when clinical data are needed. For the first time, our work has identified, defined and organized the scientific grounds on which significant benefit is granted in the European Union, based on a review of the orphan medicinal products authorized in the years 2000-2015, and on the working experience of the Committee of Orphan Medicinal Products. The resulting conceptual framework is a tool for medicine developers to reflect on potential areas of advantage of their candidate products, and for a broad range of stakeholders to stimulate the discussion on the added value of orphan medicines across the whole development lifecycle.

Nonclinical data supporting orphan medicinal product designations: lessons from rare neurological conditions.

Here, we provide an in-depth literature and experience-based review of nonclinical models and data used to support orphan medicinal product designations (OMPDs) in rare neurodegenerative conditions. The Committee for Orphan Medicinal Products (COMP) of the European Medicines Agency updates its assessment processes based on scientific progress and aims to provide transparent criteria required in support of OMPDs. Thus, we also provide an updated analysis of existing nonclinical models in selected conditions and identify key features of nonclinical studies that are crucial for the support of OMPDs. This could not only inform future drug development in rare neurological conditions, but also indicate areas where the use of nonclinical models can be made more efficient.

Establishing rarity in the context of orphan medicinal product designation in the European Union.

In the European Union (EU) legislative framework for orphan medicinal product designation, establishing that a condition affects not more than five in 10,000 people is a prerequisite for applications based on rarity. Demonstrating this requirement to the Committee of Orphan Medicinal Products (COMP) can be a particularly challenging task for sponsors. Here, we identify and examine three common issues with the estimation of prevalence in orphan drug applications in the EU (the discernment between diagnosed and undiagnosed cases; the duration of the disease; and the need for an explicit contemporary conclusion) as critical factors for acceptable prevalence estimation. These concerns are discussed in detail based on recent examples of applications, which are reflected in published European Medicines Agency (EMA) documents.

Activation of MAPK overrides the termination of myelin growth and replaces Nrg1/ErbB3 signals during Schwann cell development and myelination.

Myelination depends on the synthesis of large amounts of myelin transcripts and proteins and is controlled by Nrg1/ErbB/Shp2 signaling. We developed a novel pulse labeling strategy based on stable isotope labeling with amino acids in cell culture (SILAC) to measure the dynamics of myelin protein production in mice. We found that protein synthesis is dampened in the maturing postnatal peripheral nervous system, and myelination then slows down. Remarkably, sustained activation of MAPK signaling by expression of the Mek1DD allele in mice overcomes the signals that end myelination, resulting in continuous myelin growth. MAPK activation leads to minor changes in transcript levels but massively up-regulates protein production. Pharmacological interference in vivo demonstrates that the effects of activated MAPK signaling on translation are mediated by mTOR-independent mechanisms but in part also by mTOR-dependent mechanisms. Previous work demonstrated that loss of ErbB3/Shp2 signaling impairs Schwann cell development and disrupts the myelination program. We found that activated MAPK signaling strikingly compensates for the absence of ErbB3 or Shp2 during Schwann cell development and myelination.