Twincore Center for Experimental

Hannover, Germany

Twincore Center for Experimental

Hannover, Germany
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Bankwitz D.,Twincore Center for Experimental | Steinmann E.,Twincore Center for Experimental | Bitzegeio J.,Twincore Center for Experimental | Ciesek S.,Twincore Center for Experimental | And 9 more authors.
Journal of Virology | Year: 2010

The variability of the hepatitis C virus (HCV), which likely contributes to immune escape, is most pronounced in hypervariable region 1 (HVR1) of viral envelope protein 2. This domain is the target for neutralizing antibodies, and its deletion attenuates replication in vivo. Here we characterized the relevance of HVR1 for virus replication in vitro using cell culture-derived HCV. We show that HVR1 is dispensable for RNA replication. However, viruses lacking HVR1 (ΔHVR1) are less infectious, and separation by density gradients revealed that the population of ΔHVR1 virions comprises fewer particles with low density. Strikingly, ΔHVR1 particles with intermediate density (1.12 g/ml) are as infectious as wild-type virions, while those with low density (1.02 to 1.08 g/ml) are poorly infectious, despite quantities of RNA and core similar to those in wild-type particles. Moreover, ΔHVR1 particles exhibited impaired fusion, a defect that was partially restored by an E1 mutation (I347L), which also rescues infectivity and which was selected during long-term culture. Finally, ΔHVR1 particles were no longer neutralized by SR-B1-specific immunoglobulins but were more prone to neutralization and precipitation by soluble CD81, E2-specific monoclonal antibodies, and patient sera. These results suggest that HVR1 influences the biophysical properties of released viruses and that this domain is particularly important for infectivity of low-density particles. Moreover, they indicate that HVR1 obstructs the viral CD81 binding site and conserved neutralizing epitopes. These functions likely optimize virus replication, facilitate immune escape, and thus foster establishment and maintenance of a chronic infection. Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Zhao Y.,UK National Institute for Biological Standards and Control | Stepto H.,UK National Institute for Biological Standards and Control | Schneider C.K.,UK National Institute for Biological Standards and Control | Schneider C.K.,Twincore Center for Experimental
Human Gene Therapy Methods | Year: 2017

Gene therapy is a rapidly evolving field. So far, there have been >2,400 gene therapy products in clinical trials and four products on the market. A prerequisite for producing gene therapy products is ensuring their quality and safety. This requires appropriately controlled and standardized production and testing procedures that result in consistent safety and efficacy. Assuring the quality and safety of lentivirus-based gene therapy products in particular presents a great challenge because they are cell-based multigene products that include viral and therapeutic proteins as well as modified cells. In addition to the continuous refinement of a product, changes in production sites and manufacturing processes have become more and more common, posing challenges to developers regarding reproducibility and comparability of results. This paper discusses the concept of developing a first World Health Organization International Standard, suitable for the standardization of assays and enabling comparison of cross-trial and cross-manufacturing results for this important vector platform. The standard will be expected to optimize the development of gene therapy medicinal products, which is especially important, given the usually orphan nature of the diseases to be treated, naturally hampering reproducibility and comparability of results. © Copyright 2017, Mary Ann Liebert, Inc.

Buttel I.C.,Paul Ehrlich Institute | Chamberlain P.,NDA Advisory Board | Chowers Y.,Rambam Health Care Campus | Ehmann F.,European Medicines Agency EMA | And 21 more authors.
Biologicals | Year: 2011

Therapeutic proteins provide innovative and effective therapies for numerous diseases. However, some of these products are associated with unwanted immunogenicity that may lead to clinical consequences such as reduced or loss of efficacy, altered pharmacokinetics (PK), general immune and hypersensitivity reactions, and neutralisation of the natural counterpart (e.g. the physiological hormone). Regulatory guidance on immunogenicity assessment needs to take into consideration a great diversity of products, indications and patient populations as well as constantly advancing manufacturing technologies. Such guidance needs to be sufficiently specific while, at the same time, allowing interactive discussion and adjusted benefit-risk weighing of each product on a case-by-case basis, e.g. for a unique treatment of a life threatening disease acceptable treatment risks may differ considerably from the ones in case of less serious disease. This theme was the focus of the international conference " Taking immunogenicity assessment of therapeutic proteins to the next level" , held at the Paul-Ehrlich-Institut in Langen, Germany, on the 10-11. June 2010. The objectives of the conference were to highlight how the field could move from that of a mere description of risk factors to a system of risk assessment and mitigation, as well as an understanding of the impact of unwanted immunogenicity on the overall benefit/risk consideration for a medicinal product. More than 150 experts from industry, academia and regulatory authorities worldwide discussed the phenomenon of undesired immunogenicity from different perspectives. The conference focussed on issues relevant to three areas: (1) new European guidelines that are currently the subject of discussion; (2) testing strategies for immunogenicity assessment; and (3) scientific progress on the product-related factors that may contribute to the development of pathogenesis of immunogenicity, in particular in the field of protein aggregation and post-translational modifications. This report provides an overview of issues, insights, and conclusions that were discussed and achieved during the meeting. © 2011.

Callreus T.,Danish Health and Medicines Authority | Schneider C.K.,Danish Health and Medicines Authority | Schneider C.K.,Twincore Center for Experimental | Schneider C.K.,European Medicines Agency EMA
Pharmaceutical Medicine | Year: 2013

Against a backdrop of increasing costs and poor productivity, the concept of 'regulatory science' has sometimes been invoked in recent years in discussions regarding regulation of pharmaceuticals. There is not one generally accepted definition of regulatory science; however, there are several proposed definitions centered on a common theme: the 'brand of science' (knowledge, tools, concepts, etc.) that underpins and evolves regulatory decision making. This article provides a short review of the origins and features of regulatory science in addition to an exploration of its current and potential future role in pharmaceutical medicine. Moreover, the article discusses how regulatory science differs from traditional academic science and how it is related to the concept of regulatory affairs. It is concluded that the emerging field of regulatory science is likely to influence the future shaping and implementation of laws and regulations. © 2013 Springer International Publishing Switzerland.

Greten T.F.,Hannover Medical School | Greten T.F.,Twincore Center for Experimental | Ormandy L.A.,Hannover Medical School | Ormandy L.A.,University of Gottingen | And 10 more authors.
Journal of Immunotherapy | Year: 2010

Immunotherapy represents a potential therapeutic option for patients with hepatocellular carcinoma (HCC). However, CD4CD25Foxp regulatory T cells, which suppress potential antigen-specific T-cell responses, are increased in patients with HCC and might impair the effect of an immune-based therapeutic approach. In this study, we demonstrate that depletion of regulatory T cells in vitro unmasks α-fetoprotein-specific T-cell responses in HCC patients. On the basis of these results, we performed a clinical trial, in which 13 patients with advanced HCC ineligible for any other type of treatment were treated with 150, 250, or 350 mg/m cyclophosphamide on day 1 and 29 to suppress regulatory T cells in these patients (NCT00396682). The primary end point of this trial was regulatory T-cell number and function. Low-dose cyclophosphamide treatment (150 and 250 mg/m) induced a decrease in the absolute and relative frequency of CD4CD25Foxp regulatory T cells in peripheral blood on days 8 and 29. Suppressor function of regulatory T cells was impaired after treatment of patients with 250 mg/m on days 8 and 21. Finally, α-fetoprotein-specific T-cell responses were unmasked in 6/13 treated patients. In summary, systemic treatment of HCC patients with low-dose cyclophosphamide decreases the frequency and suppressor function of circulating CD4CD25Foxp regulatory T cells in peripheral blood and could be used in combination with immunotherapeutic approaches in HCC. Copyright © 2010 by Lippincott Williams & Wilkins.

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