Safety and Pharmacokinetics of Single Intravenous Dose of MGAWN1, a Novel Monoclonal Antibody to West Nile Virus

West Nile Virus (WNV) is a neurotropic flavivirus that can cause debilitating diseases, such as encephalitis, meningitis, or flaccid paralysis. We report the safety, pharmacokinetics, and immunogenicity of a recombinant humanized monoclonal antibody (MGAWN1) targeting the E protein of WNV in a phase 1 study, the first to be performed on humans. A single intravenous infusion of saline or of MGAWN1 at escalating doses (0.3, 1, 3, 10, or 30 mg/kg of body weight) was administered to 40 healthy volunteers (30 receiving MGAWN1; 10 receiving placebo). Subjects were evaluated on days 0, 1, 3, 7, 14, 21, 28, 42, 56, 91, 120, and 180 by clinical assessments, clinical laboratory studies, electrocardiograms (ECGs), and pharmacokinetic and immunogenicity assays. All 40 subjects tolerated the infusion of the study drug, and 39 subjects completed the study. One serious adverse event of schizophrenia occurred in the 0.3-mg/kg cohort. One grade 3 neutropenia occurred in the 3-mg/kg cohort. Six MGAWN1-treated subjects experienced 11 drug-related adverse events, including diarrhea (1 subject), chest discomfort (1), oral herpes (1), rhinitis (1), neutropenia (2), leukopenia (1), dizziness (1), headache (2), and somnolence (1). In the 30-mg/kg cohort, MGAWN1 had a half-life of 26.7 days and a maximum concentration in serum (C_max) of 953 μg/ml. This study suggests that single infusions of MGAWN1 up to 30 mg/kg appear to be safe and well tolerated in healthy subjects. The C_max of 953 μg/ml exceeds the target level in serum estimated from hamster studies by 28-fold and should provide excess WNV neutralizing activity and penetration into the brain and cerebrospinal fluid (CSF). Further evaluation of MGAWN1 for the treatment of West Nile virus infections is warranted.West Nile Virus (WNV) is a neurotropic enveloped flavivirus. Since 1999, there have been more than 29,000 cases of confirmed symptomatic WNV infection in the United States, which include more than 12,000 cases of West Nile neuroinvasive disease (WNND) and more than 1,100 deaths. WNND is estimated to occur in approximately 1 of 150 infections, and it is likely that as many as 2 million people have been infected by the virus (4, 11, 13, 16, 20). WNV is now the most common cause of epidemic viral encephalitis in the United States, and it will likely remain an important cause of neurological disease for the foreseeable future (5). No effective therapy or vaccine is available for humans.Anecdotal case reports of WNV encephalitis patients who were treated with intravenous immunoglobulin (IVIG) from convalescent WNV-infected persons provide some support for the efficacy of neutralizing antibodies against WNV (2). A placebo-controlled, randomized, double-blind human clinical trial with an IVIG product (Omr-IgG-am), which was sponsored by the Collaborative Antiviral Study Group (CASG), was terminated in December 2006. As of April 2010, no analysis of the data had been published.MGAWN1 is a high-affinity, humanized monoclonal antibody (MAb) that specifically recognizes the E (envelope) protein of WNV (12). MGAWN1 exhibits neutralizing and fusion-inhibitory activity against WNV but exhibits no reactivity or neutralization of closely or distantly related flaviviruses (14). The mechanism of virus neutralization and clearance likely involves the binding of MGAWN1 to cell surface-attached virus particles (12) and the prevention of E protein conformational changes required to release virus core particles from the endosomes into the cytoplasm (22).Pharmacology studies have demonstrated that MGAWN1 is effective both prophylactically and therapeutically in WNV-infected mice and hamsters (8-10, 14). A single dose of MGAWN1 significantly improves survival when administered as late as 5 days postinfection, a time after the establishment of neurological infection. Toxicology studies performed on uninfected rats have revealed no toxicities at single intravenous doses as high as 100 mg/kg of body weight. At 300 mg/kg, minimal to moderate hypertrophy of cells lining the hepatic sinusoids and increased mitotic hepatocytes were noted in female animals at 14 days postinfusion, although no changes in serum chemistry, including liver function test results, were detected. Based on these data, the NOAEL (no-observed-adverse-effect level) was determined to be 100 mg/kg.This phase 1 study evaluated the safety, tolerability, and pharmacokinetics (PK) of single escalating doses of MGAWN1 in healthy subjects.     

Monoclonal antibody produced in plants efficiently treats West Nile virus infection in mice

Over the past decade, West Nile virus (WNV) has spread to all 48 of the lower United States as well as to parts of Canada, Mexico, the Caribbean, and South America, with outbreaks of neuroinvasive disease occurring annually. At present, no therapeutic or vaccine is available for human use. Epidemics of WNV and other emerging infectious disease threats demand cost-efficient and scalable production technologies that can rapidly transfer effective therapeutics into the clinical setting. We have previously reported that Hu-E16, a humanized anti-WNV mAb, binds to a highly conserved epitope on the envelope protein, blocks viral fusion, and shows promising postexposure therapeutic activity. Herein, we generated a plant-derived Hu-E16 mAb that can be rapidly scaled up for commercial production. Plant Hu-E16 was expressed at high levels within 8 days of infiltration in Nicotiana benthamiana plants and retained high-affinity binding and potent neutralizing activity in vitro against WNV. A single dose of plant Hu-E16 protected mice against WNV-induced mortality even 4 days after infection at rates that were indistinguishable from mammalian-cell-produced Hu-E16. This study demonstrates the efficacy of a plant-produced mAb against a potentially lethal infection several days after exposure in an animal challenge model and provides a proof of principle for the development of plant-derived mAbs as therapy against emerging infectious diseases.     

That's just life: older adult constructs of trauma

Objectives: Researcher, clinical professional and lay understandings of the meaning of trauma may differ. An awareness of older people's perspectives on trauma may be important, given the potential for historical and cultural features to shape how the term is conceptualised among this group, thereby influencing related help-seeking behaviour.

Method: Older people living in Essex, Cambridgeshire and Suffolk were interviewed about their perceptions of the term, as was a group of mental health professionals who work with the elderly.

Results: Many older people regarded significant adversity as just part of life, with collectively understood methods of avoidance or limited support-seeking pointing to emotional management through non-disclosure. This position seemed further informed by views that disclosure may be self-indulgent, which is in stark contrast to the historical and cultural background in which many older people were raised. The professionals also suggested that some older people may be unused to expressing their emotions. The concept of trauma seems to be relative, with stigma and shame appearing to influence the way that responses to adversity are managed by this age group.

Conculsion: We conclude that focused history taking by clinicians may be needed to help elicit symptoms of trauma among elderly patients, while at the same time services might engage in a compassionate dialogue to encourage those suffering in silence to seek help.     

Implications of Recent Neuroscientific Findings in Patients with Disorders of Consciousness

A pressing issue in neuroscience is the high rate of misdiagnosis of disorders of consciousness. As new research on patients with disorders of consciousness has revealed surprising and previously unknown cognitive capacities, the need to develop better and more reliable methods of diagnosing these disorders becomes more urgent. So too the need to expand our ethical and social frameworks for thinking about these patients, to accommodate new concerns that will accompany new revelations. A recent study on trace conditioning and learning in vegetative and minimally conscious patients shows promise as a potential diagnostic and prognostic tool, both for differentiating between states of diminished consciousness, and for predicting patient outcomes, but it also generates fresh concerns about quality of life in patients previously thought to be completely unaware. Optimism about progress in diagnosing and treating disorders of consciousness must be tempered by the understanding that not all progress will necessarily be good for all patients. The prognosis for most patients remains bleak, and we must remain vigilant to acute questions and concerns about welfare and quality of life.     

Fc optimization of therapeutic antibodies enhances their ability to kill tumor cells in vitro and controls tumor expansion in vivo via low-affinity activating Fcgamma receptors

Monoclonal antibodies (mAb) are widely used in the treatment of non-Hodgkin's lymphoma and autoimmune diseases. Although the mechanism of action in vivo is not always known, the therapeutic activity of several approved mAbs depends on the binding of the Fcgamma regions to low-affinity Fcgamma receptors (FcgammaR) expressed on effector cells. We did functional genetic screens to identify IgG1 Fc domains with improved binding to the low-affinity activating Fc receptor CD16A (FcgammaRIIIA) and reduced binding to the low-affinity inhibitory Fc receptor, CD32B (FcgammaRIIB). Identification of new amino acid residues important for FcgammaR binding guided the construction of an Fc domain that showed a dramatically enhanced CD16A binding and greater than a 100-fold improvement in antibody-dependent cell-mediated cytotoxicity. In a xenograft murine model of B-cell malignancy, the greatest enhancement of an Fc-optimized anti-human B-cell mAb was accounted for by improved binding to FcgammaRIV, a unique mouse activating FcgammaR that is expressed by monocytes and macrophages but not natural killer (NK) cells, consistent with experimental and clinical data suggesting that mononuclear phagocytes, effector cells expressing both activating and inhibitory FcgammaR, are critical mediators of B-cell depletion in vivo. By using mice transgenic for human CD16A, enhanced survival was observed due to expression of CD16A-158(phe) on monocytes and macrophages as well as on NK cells in these mice. The design of new generations of improved antibodies for immunotherapy should aim at Fc optimization to increase the engagement of activating FcgammaR present on the surface of tumor-infiltrating effector cell populations.     

Nonclinical evaluation of GMA161--an antihuman CD16 (FcγRIII) monoclonal antibody for treatment of autoimmune disorders in CD16 transgenic mice

Fc receptors are a critical component of the innate immune system responsible for the recognition of cross-linked antibodies and the subsequent clearance of pathogens. However, in autoimmune diseases, these receptors play a role in the deleterious action of self-directed antibodies and as such are candidate targets for treatment. GMA161 is an aglycosyl, humanized version of the murine antibody 3G8 that targets the human low-affinity Fcγ receptor III (CD16). As CD16 expression and sequence have high species specificity, preclinical assessments were conducted in mice transgenic for both isoforms of human CD16, CD16A, and CD16B. This transgenic mouse model was useful in transitioning into phase I clinical trials, as it generated positive efficacy data in a relevant disease model and an acceptable single-dose safety profile. However, when GMA161 or its murine parent 3G8 were dosed repeatedly in transgenic mice having both human CD16 isoforms, severe reactions were observed that were not associated with significant cytokine release, nor were they alleviated by antihistamine administration. Prophylactic dosing with an inhibitor of platelet-activating factor (PAF), however, completely eliminated all signs of hypersensitivity. These findings suggest that (1) GMA161 elicits a reaction that is target dependent, (2) immunogenicity and similar adverse reactions were observed with a murine version of the antibody, and (3) the reaction is driven by the atypical hypersensitivity pathway mediated by PAF.     

Memory B cells, but not long-lived plasma cells, possess antigen specificities for viral escape mutants

Memory B cells (MBCs) and long-lived plasma cells (LLPCs) persist after clearance of infection, yet the specific and nonredundant role MBCs play in subsequent protection is unclear. After resolution of West Nile virus infection in mice, we demonstrate that LLPCs were specific for a single dominant neutralizing epitope, such that immune serum poorly inhibited a variant virus that encoded a mutation at this critical epitope. In contrast, a large fraction of MBC produced antibody that recognized both wild-type (WT) and mutant viral epitopes. Accordingly, antibody produced by the polyclonal pool of MBC neutralized WT and variant viruses equivalently. Remarkably, we also identified MBC clones that recognized the mutant epitope better than the WT protein, despite never having been exposed to the variant virus. The ability of MBCs to respond to variant viruses in vivo was confirmed by experiments in which MBCs were adoptively transferred or depleted before secondary challenge. Our data demonstrate that class-switched MBC can respond to variants of the original pathogen that escape neutralization of antibody produced by LLPC without a requirement for accumulating additional somatic mutations.