Mice genetically engineered to be humanized for their Ig genes allow for human antibody responses within a mouse background (HumAb mice), providing a valuable platform for the generation of fully ...human therapeutic antibodies. Unfortunately, existing HumAb mice do not have fully functional immune systems, perhaps because of the manner in which their genetic humanization was carried out. Heretofore, HumAb mice have been generated by disrupting the endogenous mouse Ig genes and simultaneously introducing human Ig transgenes at a different and random location; KO-plus-transgenic humanization. As we describe in the companion paper, we attempted to make mice that more efficiently use human variable region segments in their humoral responses by precisely replacing 6 Mb of mouse Ig heavy and kappa light variable region germ-line gene segments with their human counterparts while leaving the mouse constant regions intact, using a unique in situ humanization approach. We reasoned the introduced human variable region gene segments would function indistinguishably in their new genetic location, whereas the retained mouse constant regions would allow for optimal interactions and selection of the resulting antibodies within the mouse environment. We show that these mice, termed VelocImmune mice because they were generated using VelociGene technology, efficiently produce human:mouse hybrid antibodies (that are rapidly convertible to fully human antibodies) and have fully functional humoral immune systems indistinguishable from those of WT mice. The efficiency of the VelocImmune approach is confirmed by the rapid progression of 10 different fully human antibodies into human clinical trials.
Traditional approaches to antimicrobial drug development are poorly suited to combatting the emergence of novel pathogens. Additionally, the lack of small animal models for these infections hinders ...the in vivo testing of potential therapeutics. Here we demonstrate the use of the VelocImmune technology (a mouse that expresses human antibody-variable heavy chains and κ light chains) alongside the VelociGene technology (which allows for rapid engineering of the mouse genome) to quickly develop and evaluate antibodies against an emerging viral disease. Specifically, we show the rapid generation of fully human neutralizing antibodies against the recently emerged Middle East Respiratory Syndrome coronavirus (MERS-CoV) and development of a humanized mouse model for MERS-CoV infection, which was used to demonstrate the therapeutic efficacy of the isolated antibodies. The VelocImmune and VelociGene technologies are powerful platforms that can be used to rapidly respond to emerging epidemics.
Traditional approaches for development of antibodies are poorly suited to combating the emergence of novel pathogens, as they require multiple steps of laborious optimization and process adaptation for clinical development. Here, we describe the simultaneous use of two state-of-the-art technologies to rapidly generate and validate antibodies against Middle East Respiratory Syndrome coronavirus (MERS-CoV), following a highly optimized process that links immunization to production of clinical material grade antibodies and developed promising clinical candidates for prophylaxis and treatment of MERS-CoV, and a humanized mouse model of infection that was used to evaluate our therapeutics. This study forms the basis for a rapid response to address the public threat resulting from emerging coronaviruses or other pathogens that pose a serious threat to human health in the future.
Cytokines can initiate and perpetuate human diseases, and are among the best-validated of therapeutic targets. Cytokines can be blocked by the use of soluble receptors; however, the use of this ...approach for cytokines such as interleukin (IL)-1, IL-4, IL-6 and IL-13 that use multi-component receptor systems is limited because monomeric soluble receptors generally exhibit low affinity or function as agonists. We describe here a generally applicable method to create very high-affinity blockers called 'cytokine traps' consisting of fusions between the constant region of IgG and the extracellular domains of two distinct cytokine receptor components involved in binding the cytokine. Traps potently block cytokines in vitro and in vivo and represent a substantial advance in creating novel therapeutic candidates for cytokine-driven diseases.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
For most classes of drugs, rapid development of therapeutics to treat emerging infections is challenged by the timelines needed to identify compounds with the desired efficacy, safety, and ...pharmacokinetic profiles. Fully human monoclonal antibodies (mAbs) provide an attractive method to overcome many of these hurdles to rapidly produce therapeutics for emerging diseases.
In this study, we deployed a platform to generate, test, and develop fully human antibodies to Zaire ebolavirus. We obtained specific anti-Ebola virus (EBOV) antibodies by immunizing VelocImmune mice that use human immunoglobulin variable regions in their humoral responses.
Of the antibody clones isolated, 3 were selected as best at neutralizing EBOV and triggering FcγRIIIa. Binding studies and negative-stain electron microscopy revealed that the 3 selected antibodies bind to non-overlapping epitopes, including a potentially new protective epitope not targeted by other antibody-based treatments. When combined, a single dose of a cocktail of the 3 antibodies protected nonhuman primates (NHPs) from EBOV disease even after disease symptoms were apparent.
This antibody cocktail provides complementary mechanisms of actions, incorporates novel specificities, and demonstrates high-level postexposure protection from lethal EBOV disease in NHPs. It is now undergoing testing in normal healthy volunteers in preparation for potential use in future Ebola epidemics.
Vascular endothelial growth factor (VEGF) plays a critical role during normal embryonic angiogenesis and also in the pathological angiogenesis that occurs in a number of diseases, including cancer. ...Initial attempts to block VEGF by using a humanized monoclonal antibody are beginning to show promise in human cancer patients, underscoring the importance of optimizing VEGF blockade. Previous studies have found that one of the most effective ways to block the VEGF-signaling pathway is to prevent VEGF from binding to its normal receptors by administering decoy-soluble receptors. The highest-affinity VEGF blocker described to date is a soluble decoy receptor created by fusing the first three Ig domains of VEGF receptor 1 to an Ig constant region; however, this fusion protein has very poor in vivo pharmacokinetic properties. By determining the requirements to maintain high affinity while extending in vivo half life, we were able to engineer a very potent high-affinity VEGF blocker that has markedly enhanced pharmacokinetic properties. This VEGF-Trap effectively suppresses tumor growth and vascularization in vivo, resulting in stunted and almost completely avascular tumors. VEGF-Trap-mediated blockade may be superior to that achieved by other agents, such as monoclonal antibodies targeted against the VEGF receptor.
INTRODUCTION: High grade glioma (HGG) remains resistant to standard therapies. Newer approaches, such as immunotherapy, hold great promise. Viral infection and killing of tumor cells can stimulate ...antitumor immune responses. A Phase 1 clinical study using an investigational retroviral replicating vector, Toca 511, injected intratumorally, in combination with investigational oral Toca FC (extended-release 5-FC) is being conducted. METHODS: The primary purpose of this study is to identify the highest safe and well tolerated dose of Toca 511 administered transcranially into recurrent HGG tumors. The starting dose was 3.9 x 10 similar to Transducing Units (TU). Using a standard 3 + 3 design, doses have been escalated at half log intervals to 1.5 x 10 { TU. 24 subjects were injected using a brain biopsy needle. Addition of gadolinium to the vector with post-operative iMRI suggested variable delivery of vector to the tumor. Subsequently 12 subjects have been treated using CED under real-time MRI-guidance. Monthly cycles of oral 5-FC are started 4 weeks after injection of the vector. RESULTS: 36 subjects across 5 vector dosing cohorts have been studied. Real-time MRI-guidance demonstrated vector delivery with confirmation of vector RNA and CD protein in tumor samples. The injection procedures and vector and 5-FC dosing have been safe and well tolerated to date. No DLTs have been observed. Tumors have been observed to regress in the area around vector infusion and some subjects have experienced improvement in clinical symptoms. A number of subjects have experienced prolonged survival with 8 of the first 17 subjects with Grade 4 tumors surviving more than 1 year. CONCLUSION: This study confirms the feasibility and safety of transcranial, intratumoral delivery of an RRV. Continued dose escalation is planned and may yield further gains in efficacy.
OBJECTIVE:
To evaluate the management strategies available for the complications associated with bacillus Calmette–Guérin (BCG) immunotherapy in the treatment of bladder cancer.
DATA SOURCES:
...Clinical literature accessed through MEDLINE (January 1983–January 1999). Key search terms included bacillus Calmette-Guérin, BCG, and bladder cancer.
DATA SYNTHESIS:
BCG vaccine is a live-attenuated strain of Mycobacterium bovis; therefore, the risk for complications exists. An evaluation of treatment regimens was conducted, and the management strategies are presented.
CONCLUSIONS:
The complications associated with BCG immunotherapy range from local reactions to potentially fatal systemic reactions requiring long-term therapy. Therefore, healthcare practitioners need to be aware of the current treatment regimens available.
Angiopoietins are a recently discovered family of angiogenic factors that interact with the endothelial receptor tyrosine kinase Tie2, either as agonists (angiopoietin-1) or as context-dependent ...agonists/antagonists (angiopoietin-2). Here we show that angiopoietin-1 has a modular structure unlike any previously characterized growth factor. This modular structure consists of a receptor-binding domain, a dimerization motif and a superclustering motif that forms variable-sized multimers. Genetic engineering of precise multimers of the receptor-binding domain of angiopoietin-1, using surrogate multimerization motifs, reveals that tetramers are the minimal size required for activating endothelial Tie2 receptors. In contrast, engineered dimers can antagonize endothelial Tie2 receptors. Surprisingly, angiopoietin-2 has a modular structure and multimerization state similar to that of angiopoietin-1, and its antagonist activity seems to be a subtle property encoded in its receptor-binding domain.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The angiopoietins have recently joined the members of the vascular endothelial growth factor family as the only known growth factors largely specific for vascular endothelium. The angiopoietins ...include a naturally occurring agonist, angiopoietin-1, as well as a naturally occurring antagonist, angiopoietin-2, both of which act by means of the Tie2 receptor. We now report our attempts to use homology-based cloning approaches to identify new members of the angiopoietin family. These efforts have led to the identification of two new angiopoietins, angiopoietin-3 in mouse and angiopoietin-4 in human; we have also identified several more distantly related sequences that do not seem to be true angiopoietins, in that they do not bind to the Tie receptors. Although angiopoietin-3 and angiopoietin-4 are strikingly more structurally diverged from each other than are the mouse and human versions of angiopoietin-1 and angiopoietin-2, they appear to represent the mouse and human counterparts of the same gene locus, as revealed in our chromosomal localization studies of all of the angiopoietins in mouse and human. The structural divergence of angiopoietin-3 and angiopoietin-4 appears to underlie diverging functions of these counterparts. Angiopoietin-3 and angiopoietin-4 have very different distributions in their respective species, and angiopoietin-3 appears to act as an antagonist, whereas angiopoietin-4 appears to function as an agonist.
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