Valerie Gafner

An Effector-Reduced Anti-β-Amyloid (Aβ) Antibody with Unique Aβ Binding Properties Promotes Neuroprotection and Glial Engulfment of Aβ

Passive immunization against β-amyloid (Aβ) has become an increasingly desirable strategy as a therapeutic treatment for Alzheimers disease (AD). However, traditional passive immunization approaches carry the risk of Fcγ receptor-mediated overactivation of microglial cells, which may contribute to an inappropriate proinflammatory response leading to vasogenic edema and cerebral microhemorrhage. Here, we describe the generation of a humanized anti-Aβ monoclonal antibody of an IgG4 isotype, known as MABT5102A (MABT). An IgG4 subclass was selected to reduce the risk of Fcγ receptor-mediated overactivation of microglia. MABT bound with high affinity to multiple forms of Aβ, protected against Aβ1–42 oligomer-induced cytotoxicity, and increased uptake of neurotoxic Aβ oligomers by microglia. Furthermore, MABT-mediated amyloid plaque removal was demonstrated using in vivo live imaging in hAPP(V717I)/PS1 transgenic mice. When compared with a human IgG1 wild-type subclass, containing the same antigen-binding variable domains and with equal binding to Aβ, MABT showed reduced activation of stress-activated p38MAPK (p38 mitogen-activated protein kinase) in microglia and induced less release of the proinflammatory cytokine TNFα. We propose that a humanized IgG4 anti-Aβ antibody that takes advantage of a unique Aβ binding profile, while also possessing reduced effector function, may provide a safer therapeutic alternative for passive immunotherapy for AD. Data from a phase I clinical trial testing MABT is consistent with this hypothesis, showing no signs of vasogenic edema, even in ApoE4 carriers.

Efficacy and Safety of A Liposome-Based Vaccine against Protein Tau, Assessed in Tau.P301L Mice That Model Tauopathy

Progressive aggregation of protein Tau into oligomers and fibrils correlates with cognitive decline and synaptic dysfunction, leading to neurodegeneration in vulnerable brain regions in Alzheimers disease. The unmet need of effective therapy for Alzheimers disease, combined with problematic pharmacological approaches, led the field to explore immunotherapy, first against amyloid peptides and recently against protein Tau. Here we adapted the liposome-based amyloid vaccine that proved safe and efficacious, and incorporated a synthetic phosphorylated peptide to mimic the important phospho-epitope of protein Tau at residues pS396/pS404. We demonstrate that the liposome-based vaccine elicited, rapidly and robustly, specific antisera in wild-type mice and in Tau.P301L mice. Long-term vaccination proved to be safe, because it improved the clinical condition and reduced indices of tauopathy in the brain of the Tau.P301L mice, while no signs of neuro-inflammation or other adverse neurological effects were observed. The data corroborate the hypothesis that liposomes carrying phosphorylated peptides of protein Tau have considerable potential as safe and effective treatment against tauopathies, including Alzheimers disease.

TLR4- and TRIF-dependent stimulation of B lymphocytes by peptide liposomes enables T cell-independent isotype switch in mice.

Immunoglobulin class switching from IgM to IgG in response to peptides is generally T cell-dependent and vaccination in T cell-deficient individuals is inefficient. We show that a vaccine consisting of a dense array of peptides on liposomes induced peptide-specific IgG responses totally independent of T-cell help. Independency was confirmed in mice lacking T cells and in mice deficient for MHC class II, CD40L, and CD28. The IgG titers were high, long-lived, and comparable with titers obtained in wild-type animals, and the antibody response was associated with germinal center formation, expression of activation-induced cytidine deaminase, and affinity maturation. The T cell-independent (TI) IgG response was strictly dependent on ligation of TLR4 receptors on B cells, and concomitant TLR4 and cognate B-cell receptor stimulation was required on a single-cell level. Surprisingly, the IgG class switch was mediated by TIR-domain-containing adapter inducing interferon-β (TRIF), but not by MyD88. This study demonstrates that peptides can induce TI isotype switching when antigen and TLR ligand are assembled and appropriately presented directly to B lymphocytes. A TI vaccine could enable efficient prophylactic and therapeutic vaccination of patients with T-cell deficiencies and find application in diseases where induction of T-cell responses contraindicates vaccination, for example, in Alzheimer disease.

Novel Phospho-Tau Monoclonal Antibody Generated Using a Liposomal Vaccine, with Enhanced Recognition of a Conformational Tauopathy Epitope

The microtubule-associated protein Tau is an intrinsically unfolded, very soluble neuronal protein. Under still unknown circumstances, Tau protein forms soluble oligomers and insoluble aggregates that are closely linked to the cause and progression of various brain pathologies, including Alzheimer’s disease. Previously we reported the development of liposome-based vaccines and their efficacy and safety in preclinical mouse models for tauopathy. Here we report the use of a liposomal vaccine for the generation of a monoclonal antibody with particular characteristics that makes it a valuable tool for fundamental studies as well as a candidate antibody for diagnostic and therapeutic applications. The specificity and affinity of antibody ACI-5400 were characterized by a panel of methods: (i) measuring the selectivity for a specific phospho-Tau epitope known to be associated with tauopathy, (ii) performing a combination of peptide and protein binding assays, (iii) staining of brain sections from mouse preclinical tauopathy models and from human subjects representing six different tauopathies, and (iv) evaluating the selective binding to pathological epitopes on extracts from tauopathy brains in non-denaturing sandwich assays. We conclude that the ACI-5400 antibody binds to protein Tau phosphorylated at S396 and favors a conformation that is typically present in the brain of tauopathy patients, including Alzheimer’s disease.

Tau antibodies lacking effector function minimize inflammatory responses while effectively blocking spread of tau pathology

P2-054 TAU ANTIBODIES LACKING EFFECTOR FUNCTION MINIMIZE INFLAMMATORY RESPONSES WHILE EFFECTIVELY BLOCKING SPREAD OF TAU PATHOLOGY Seung-Hye Lee, Claire Le Pichon, Oskar Adolfsson, Val erie Gafner, Maria Pihlgren, Han Lin, Hilda Solanoy, Robert Brendza, Hai Ngu, Oded Foreman, Ruby Chan, James Ernst, Danielle Dicara, Isidro Hotzel, Karpagam Srinivasan, David Hansen, Jasvinder Atwal, Andrea Pfeifer, Ryan Watts, Andreas Muhs, Kimberly Scearce-Levie, Gai Ayalon, Genentech, Inc., South San Francisco, CA, USA; National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA; AC Immune SA, Lausanne, Switzerland. Contact e-mail: lee.seunghye@gene.com

A liposomal anti-phospho-tau vaccine demonstrates higher immunogenicity and specificity than a classical peptide vaccine approach

However, the relationship between these two proteins and neuronal loss lacks amechanistic explanation. Furthermore, evidence from animal models suggests that amyloid beta toxicity is mediated by tau [1-6]. We hypothesize that tau oligomers formation plays curial role in driving AD pathogenesis. Thus, tau oligomers represent an ideal therapeutic target for the treatment of AD. In order to study the removal of toxic tau assemblies in an animal model of AD (Tg2576), we generated a tau oligomer specific antibody (TOMA). This antibody does not recognize the functional monomeric tau or oligomers from other amyloidogenic proteins. Methods: Here we used the Tg2576 mouse model which overexpress the human APP with the Swedish double mutations (K670N, M671L) under the control of a hamster prion protein promoter .14-month old Tg2576 mice, received a single iv injection of 30 mg of the TOMA antibody. Control group received 30 mg of non-specific IgG. Cognitive function was assessed by novel object recognition test, 15 days after injection. In addition, western blot, ELISA and Immunostaining were performed to evaluate the response to treatment. Results: Our results indicate that single iv-injection of the TOMA antibody, reduce endogenous tau oligomers and improve cognition in the Tg2576 mouse. Interestingly, removal of tau oligomers by immunotherapy decreases beta-amyloid-56* and increases deposition of plaques in immunized mice. Conclusions: Our results support the findings that tau oligomers mediate beta-amyloid toxicity in vivo. Moreover, removal of tau oligomers by immunotherapy may induce beta-amyloid aggregates to assembly into inert and perhaps protective plaques. Thus, targeting tau oligomers by immunotherapymay represent a novel strategy for the treatment of AD and other neurodegenerative tauopathies.

Novel phospho-tau-specific liposome-based vaccines to treat tau pathology

Clara Theunis, Natalia Crespo-Biel, Maria Pihlgren, Peter Borghgraef, Herman Devijver, Valerie Gafner, David Hickman, Nathalie Chuard, Maria Pilar Lopez Deber, Pedro Reis, Anna Lucia Buccarello, Oskar Adolfsson, Sigrun Roeber, Hans Kretzschmar, Andrea Pfeifer, Andreas Muhs, Fred Van Leuven, LEGTEGG Katholieke Universiteit Leuven, Leuven, Belgium; 2 ACImmune, Lausanne, Switzerland; LEGTEGGKULeuven, Leuven, Belgium; LEGTEGG-KULeuven, Leuven, Belgium; AC Immune SA, Lausanne, Switzerland; Center for Neuropathology, M€unchen, Germany; 7 AC Immune, Lausanne, Switzerland; 8 Experimental Genetics Group LEGTEGG KULeuven, Leuven, Belgium.

Novel phospho-Tau specific monoclonal antibodies for the treatment of Tau-mediated pathology

Background: Research over the last decade has highlighted the role that metals may play in the pathogenesis of Alzheimer’s disease (AD). To date, the primary end point for these studies has been s-amyloid. Recent literature supports the notion that metals may also interact with tau and be important for the formation of neurofibrillary tangles (NFTs). In this study we surveyed metal levels in the rTg(tauP301L)4510 mouse model and utilised clioquinol (CQ) to assess the effect of metal modulation on tangle pathology. Methods: Metal levels were assessed by ICPMS in cohorts of mice at either w2 months (n 1⁄4 6 WT; n 1⁄4 6 Tg) or w5 months (n 1⁄4 12 WT; n 1⁄4 11 Tg) of age. The effect of oral clioquinol (6 months of treatment, 30mg/kg) was assessed in a separate cohort of Tg (n 1⁄4 25) and WT mice (n 1⁄4 30). Drug treatment began at w6 months of age and prior to culling animals were assessed in the open field, rotarod, y-maze and water maze. Young rTg4510 mice, prior to the formation of any pathology, had significantly altered brain metal content, including elevations in zinc (25%, p 1⁄4 0.01) and copper (31%, p 1⁄4 0.02) and a trend to elevated iron (20%, p 1⁄4 0.08). In contrast, aged rTg4510 mice had significantly decreased levels of zinc (18%, p 1⁄4 0.01) and iron levels were also decreased (20%, p 1⁄4 0.06). Behavioural analysis of older mice did not reveal any effect of CQ on performance in the water maze, Y-maze or open field. In the rotarod, however, the Tg animals spent a significantly shorter amount of time on the rotarod (3.5 sec, Tg; 35 sec, WT; p < 0.0001), and clioquinol treatment of the Tg animals significantly improved their performance (10.2 sec, Tg+clioquinol; p 1⁄4 0.01 compared to Tg). Further metal analyses and histological studies are currently being finalised and will be discussed. Conclusions: We have demonstrated that there is a dysregulation in metal ion homeostasis in the rTg4510 model of tauopathy, and that there are also age-dependent alterations in metal levels that occur coincident with the evolution of neurofibrillary pathology. These data support a potential interaction between tau/NFTs and various metal ions and provide further insight into novel therapeutic approaches for the treatment of tauopathies.