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Sigurdsson EM. Tau Immunotherapies for Alzheimer's Disease and Related Tauopathies: Status of Trials and Insights from Preclinical Studies. J Alzheimers Dis 2024:JAD231238. [PMID: 38427486 DOI: 10.3233/jad-231238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
The tau protein undergoes pathological changes in Alzheimer's disease and other tauopathies that eventually lead to functional impairments. Over the years, several therapeutic approaches have been examined to slow or halt the progression of tau pathology but have yet to lead to an approved disease-modifying treatment. Of the drugs in clinical trials that directly target tau, immunotherapies are the largest category and mostly consist of antibodies in different stages of development. There is a reasonable optimism that at least some of these compounds will have a clinically meaningful efficacy. This view is based on the significant although modest efficacy of some antibodies targeting amyloid-β in Alzheimer's disease and the fact that tau pathology correlates much better with the degree of dementia than amyloid-β lesions. In Alzheimer's disease, clearing pathological tau may therefore improve function later in the disease process than when removing amyloid-β. This review provides a brief update on the active and passive clinical tau immunization trials with insight from preclinical studies. Various epitopes are being targeted and some of the antibodies are said to target extracellular tau but because almost all of pathological tau is found intracellularly, the most efficacious antibodies should be able to enter the cell.
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Affiliation(s)
- Einar M Sigurdsson
- Departments of Neuroscience and Physiology, and Psychiatry, Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
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Pai S. New insight into tau immunotherapy. AGING BRAIN 2023; 4:100089. [PMID: 37559952 PMCID: PMC10407942 DOI: 10.1016/j.nbas.2023.100089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 07/16/2023] [Indexed: 08/11/2023] Open
Affiliation(s)
- Sadashiva Pai
- Science Mission LLC, 3424 Canyon Lake Drive, Little Elm, TX 75068, United States
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Moore KBE, Hung TJ, Fortin JS. Hyperphosphorylated tau (p-tau) and drug discovery in the context of Alzheimer's disease and related tauopathies. Drug Discov Today 2023; 28:103487. [PMID: 36634842 PMCID: PMC9975055 DOI: 10.1016/j.drudis.2023.103487] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 12/14/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia, characterized by intracellular neurofibrillary tangles (NFTs) and extracellular β-amyloid (βA) plaques. No disease-modifying therapy is currently available to prevent the progression of, or cure, the disease. Misfolded hyperphosphorylated tau (p-tau) is considered a pivotal point in the pathogenesis of AD and other tauopathies. Compelling evidence suggests that it is a key driver of the accumulation of NFTs and can be directly correlated with the extent of dementia in patients with AD. Therefore, inhibiting tau hyperphosphorylation-induced aggregation could be a viable strategy to discover and develop therapeutics for patients with AD.
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Affiliation(s)
- Kendall B E Moore
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN, USA
| | - Ta-Jung Hung
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN, USA
| | - Jessica S Fortin
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN, USA.
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Congdon EE, Pan R, Jiang Y, Sandusky-Beltran LA, Dodge A, Lin Y, Liu M, Kuo MH, Kong XP, Sigurdsson EM. Single domain antibodies targeting pathological tau protein: Influence of four IgG subclasses on efficacy and toxicity. EBioMedicine 2022; 84:104249. [PMID: 36099813 PMCID: PMC9475275 DOI: 10.1016/j.ebiom.2022.104249] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 08/15/2022] [Accepted: 08/19/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Eleven tau immunoglobulin G (IgG) antibodies have entered clinical trials to treat tauopathies, including Alzheimer's disease, but it is unclear which IgG subclass/subtype has the ideal efficacy and safety profile. Only two subtypes, with or without effector function, have been examined in the clinic and not for the same tau antibody. The few preclinical studies on this topic have only compared two subtypes of one antibody each and have yielded conflicting results. METHODS We selected two single domain antibodies (sdAbs) derived from a llama immunized with tau proteins and utilized them to generate an array of Fc-(sdAb)2 subclasses containing identical tau binding domains but differing Fc region. Unmodified sdAbs and their IgG subclasses were tested for efficacy in primary cultures and in vivo microdialysis using JNPL3 tauopathy mice. FINDINGS Unmodified sdAbs were non-toxic, blocked tau toxicity and promoted tau clearance. However, the efficacy/safety profile of their Fc-(sdAb)2 subclasses varied greatly within and between sdAbs. For one of them, all its subtypes were non-toxic, only those with effector function cleared tau, and were more effective in vivo than unmodified sdAb. For the other sdAb, all its subtypes were toxic in tauopathy cultures but not in wild-type cells, suggesting that bivalent binding of its tau epitope stabilizes a toxic conformation of tau, with major implications for tau pathogenesis. Likewise, its subclasses were less effective than the unmodified sdAb in clearing tau in vivo. INTERPRETATION These findings indicate that tau antibodies with effector function are safe and better at clearing pathological tau than effectorless antibodies, Furthermore, tau antibodies can provide a valuable insight into tau pathogenesis, and some may aggravate it. FUNDING Funding for these studies was provided by the National Institute of Health (R01 AG032611, R01 NS077239, RF1 NS120488, R21 AG 069475, R21 AG 058282, T32AG052909), and the NYU Alzheimer's Disease Center Pilot Grant Program (via P30 AG008051).
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Affiliation(s)
- Erin E Congdon
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Ruimin Pan
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Yixiang Jiang
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Leslie A Sandusky-Beltran
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Andie Dodge
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Yan Lin
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Mengyu Liu
- Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Room 401, East Lansing, MI, 48824, USA
| | - Min-Hao Kuo
- Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Room 401, East Lansing, MI, 48824, USA
| | - Xiang-Peng Kong
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Einar M Sigurdsson
- Department of Neuroscience and Physiology, and the Neuroscience Institute, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA; Department of Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, USA.
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Bajracharya R, Cruz E, Götz J, Nisbet RM. Ultrasound-mediated delivery of novel tau-specific monoclonal antibody enhances brain uptake but not therapeutic efficacy. J Control Release 2022; 349:634-648. [PMID: 35901857 DOI: 10.1016/j.jconrel.2022.07.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/16/2022] [Accepted: 07/21/2022] [Indexed: 11/25/2022]
Abstract
Tau-specific immunotherapy is an attractive strategy for the treatment of Alzheimer's disease and other tauopathies. However, effectively targeting tau in the brain remains a considerable challenge due to the restrictive nature of the blood-brain barrier (BBB), which excludes an estimated >99% of peripherally administered antibodies. However, their transport across the BBB can be facilitated by a novel modality, low-intensity scanning ultrasound used in combination with intravenously injected microbubbles (SUS+MB). We have previously shown that SUS+MB-mediated delivery of a tau-specific antibody in a single-chain (scFv) format to tau transgenic mice enhanced brain and neuronal uptake and subsequently, reduced tau pathology and improved behavioural outcomes to a larger extent than either scFv or SUS+MB on its own. Here we generated a novel tau-specific monoclonal antibody, RNF5, and validated it in its IgG format in the presence or absence of SUS+MB by treating K369I tau transgenic K3 mice once weekly for 12 weeks. We found that both RNF5 and SUS+MB treatments on their own significantly reduced tau pathology. In the combination group (RNF5 + SUS+MB), however, despite increased antibody localization in the brain, there were no further reductions in tau pathology when compared to RNF5 treatment alone. Furthermore, following SUS+MB, RNF5 accumulated heavily within cells across the pyramidal cell layer of the hippocampus, that were negative for MAP2 and p-tau, suggesting that SUS+MB may not facilitate enhanced RNF5 engagement of intraneuronal tau. Overall, our new findings reveal the complexities of combining tau immunotherapy with SUS+MB and challenge the view that this is a straight-forward approach.
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Affiliation(s)
- Rinie Bajracharya
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, University of Queensland, Queensland 4072, Australia
| | - Esteban Cruz
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, University of Queensland, Queensland 4072, Australia
| | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, University of Queensland, Queensland 4072, Australia.
| | - Rebecca M Nisbet
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, University of Queensland, Queensland 4072, Australia; Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3052, Australia.
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Congdon EE, Jiang Y, Sigurdsson EM. Targeting tau only extracellularly is likely to be less efficacious than targeting it both intra- and extracellularly. Semin Cell Dev Biol 2021; 126:125-137. [PMID: 34896021 DOI: 10.1016/j.semcdb.2021.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/01/2021] [Accepted: 12/01/2021] [Indexed: 12/11/2022]
Abstract
Aggregation of the tau protein is thought to be responsible for the neurodegeneration and subsequent functional impairments in diseases that are collectively named tauopathies. Alzheimer's disease is the most common tauopathy, but the group consists of over 20 different diseases, many of which have tau pathology as their primary feature. The development of tau therapies has mainly focused on preventing the formation of and/or clearing these aggregates. Of these, immunotherapies that aim to either elicit endogenous tau antibodies or deliver exogenous ones are the most common approach in clinical trials. While their mechanism of action can involve several pathways, both extra- and intracellular, pharmaceutical companies have primarily focused on antibody-mediated clearance of extracellular tau. As we have pointed out over the years, this is rather surprising because it is well known that most of pathological tau protein is found intracellularly. It has been repeatedly shown by several groups over the past decades that antibodies can enter neurons and that their cellular uptake can be enhanced by various means, particularly by altering their charge. Here, we will briefly describe the potential extra- and intracellular mechanisms involved in antibody-mediated clearance of tau pathology, discuss these in the context of recent failures of some of the tau antibody trials, and finally provide a brief overview of how the intracellular efficacy of tau antibodies can potentially be further improved by certain modifications that aim to enhance tau clearance via specific intracellular degradation pathways.
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Affiliation(s)
- Erin E Congdon
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Grossman School of Medicine, New York, NY 10016, United States.
| | - Yixiang Jiang
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Grossman School of Medicine, New York, NY 10016, United States
| | - Einar M Sigurdsson
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University Grossman School of Medicine, New York, NY 10016, United States; Department of Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, United States.
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Benn JA, Mukadam AS, McEwan WA. Targeted protein degradation using intracellular antibodies and its application to neurodegenerative disease. Semin Cell Dev Biol 2021; 126:138-149. [PMID: 34654628 DOI: 10.1016/j.semcdb.2021.09.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/24/2021] [Accepted: 09/26/2021] [Indexed: 01/10/2023]
Abstract
Antibodies mediate the majority of their effects in the extracellular domain, or in intracellular compartments isolated from the cytosol. Under a growing list of circumstances, however, antibodies are found to gain access to the cytoplasm. Cytosolic immune complexes are bound by the atypical antibody receptor TRIM21, which mediates the rapid degradation of the immune complexes at the proteasome. These discoveries have informed the development of TRIM-Away, a technique to selectively deplete proteins using delivery of antibodies into cells. A range of related approaches that elicit selective protein degradation using intracellular constructs linking antibody fragments to degradative effector functions have also been developed. These methods hold promise for inducing the degradation of proteins as both research tools and as a novel therapeutic approach. Protein aggregates are a pathophysiological feature of neurodegenerative diseases and are considered to have a causal role in pathology. Immunotherapy is emerging as a promising route towards their selective targeting, and a role of antibodies in the cytosol has been demonstrated in cell-based assays. This review will explore the mechanisms by which therapeutic antibodies engage and eliminate intracellularly aggregated proteins. We will discuss how future developments in intracellular antibody technology may enhance the therapeutic potential of such antibody-derived therapies.
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Affiliation(s)
- Jonathan A Benn
- UK Dementia Research Institute at the University of Cambridge, Department of Clinical Neurosciences, Cambridge, UK
| | - Aamir S Mukadam
- UK Dementia Research Institute at the University of Cambridge, Department of Clinical Neurosciences, Cambridge, UK
| | - William A McEwan
- UK Dementia Research Institute at the University of Cambridge, Department of Clinical Neurosciences, Cambridge, UK.
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Therapeutic Ultrasound as a Treatment Modality for Physiological and Pathological Ageing Including Alzheimer's Disease. Pharmaceutics 2021; 13:pharmaceutics13071002. [PMID: 34371696 PMCID: PMC8309087 DOI: 10.3390/pharmaceutics13071002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/29/2021] [Accepted: 06/29/2021] [Indexed: 01/09/2023] Open
Abstract
Physiological and pathological ageing (as exemplified by Alzheimer's disease, AD) are characterized by a progressive decline that also includes cognition. How this decline can be slowed or even reversed is a critical question. Here, we discuss therapeutic ultrasound as a novel modality to achieve this goal. In our studies, we explored three fundamental strategies, (i) scanning ultrasound on its own (SUSonly), (ii) therapeutic ultrasound in concert with intravenously injected microbubbles (which transiently opens the blood-brain barrier, SUS+MB), and (iii) SUS+MB in combination with therapeutic antibodies (SUS+MB+mAb). These studies show SUS+MB effectively clears amyloid and restores memory in amyloid-depositing mice and partially clears Tau and ameliorates memory impairments in Tau transgenic mice, with additional improvements found in combination trials (SUS+MB+mAb). Interestingly, both SUSonly and SUS+MB restored the induction of long-term potentiation (LTP, electrophysiological correlate of memory) in senescent wild-type mice. Both lead to increased neurogenesis, and SUSonly, in particular, resulted in improved spatial memory. We discuss these findings side-by-side with our findings obtained in AD mouse models. We conclude that therapeutic ultrasound is a non-invasive, pleiotropic modality that may present a treatment option not only for AD but also for enhancing cognition in physiological ageing.
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Xia Y, Prokop S, Giasson BI. "Don't Phos Over Tau": recent developments in clinical biomarkers and therapies targeting tau phosphorylation in Alzheimer's disease and other tauopathies. Mol Neurodegener 2021; 16:37. [PMID: 34090488 PMCID: PMC8180161 DOI: 10.1186/s13024-021-00460-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/26/2021] [Indexed: 12/11/2022] Open
Abstract
Phosphorylation is one of the most prevalent post-translational modifications found in aggregated tau isolated from Alzheimer’s disease (AD) patient brains. In tauopathies like AD, increased phosphorylation or hyperphosphorylation can contribute to microtubule dysfunction and is associated with tau aggregation. In this review, we provide an overview of the structure and functions of tau protein as well as the physiologic roles of tau phosphorylation. We also extensively survey tau phosphorylation sites identified in brain tissue and cerebrospinal fluid from AD patients compared to age-matched healthy controls, which may serve as disease-specific biomarkers. Recently, new assays have been developed to measure minute amounts of specific forms of phosphorylated tau in both cerebrospinal fluid and plasma, which could potentially be useful for aiding clinical diagnosis and monitoring disease progression. Additionally, multiple therapies targeting phosphorylated tau are in various stages of clinical trials including kinase inhibitors, phosphatase activators, and tau immunotherapy. With promising early results, therapies that target phosphorylated tau could be useful at slowing tau hyperphosphorylation and aggregation in AD and other tauopathies.
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Affiliation(s)
- Yuxing Xia
- Department of Neuroscience, College of Medicine, University of Florida, BMS J483/CTRND, 1275 Center Drive, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Stefan Prokop
- Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA.,Department of Pathology, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA.,McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Benoit I Giasson
- Department of Neuroscience, College of Medicine, University of Florida, BMS J483/CTRND, 1275 Center Drive, Gainesville, FL, 32610, USA. .,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA. .,McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA.
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