Aug 2026· Journal of Neurology· Vol 273· 1 citation· 110 references
Medicine
TL;DR
Key biological mechanisms underlying TDP-43 pathology, emerging therapeutic strategies, and evolving approaches to clinical trial design and biomarker development are examined.
Transactive response DNA-binding protein (TDP-43) plays a key pathological role in several neurodegenerative diseases, particularly amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Despite the well-established role of TDP-43 in neurodegenerative disorders, it remains a complex area of study as it is unclear whether nuclear loss-of-function, cytoplasmic gain-of-function, or both drive pathogenesis. TDP-43 overexpression models are advantageous tools when developing drug candidates targeted at TDP-43, however, existing models often lack comprehensive RNA-seq data benchmarked against patient datasets. Given the value of TDP-43 overexpression as a model of ALS-related pathology, we have developed a stable, inducible system in a HEK293-derived cell line, offering a practical and scalable platform to investigate TDP-43 dysregulation. Utilizing this system, we found that TDP-43 overexpression reflected key features associated with ALS pathology, causing cytotoxicity, nucleocytoplasmic mislocalization, and extensive transcriptomic changes. Furthermore, comparative RNA-seq analysis between this model and ALS patient-derived data revealed substantial overlaps, where 64% of the differentially expressed genes in the TDP-43 overexpression cell line were also found to be altered in ALS patient tissue, supporting the disease relevance of the model. Genes of interest identified in the analysis included NUP85, SREBF2, VAMP5, WDR41, CDC23, DKC1, and PTS. This stable, inducible TDP-43 overexpression model and its associated transcriptomic dataset provide a versatile platform for ALS and other TDP-43 proteinopathy research, enabling the investigation of molecular drivers of TDP-43 dysfunction, the identification of potential disease-relevant pharmacological targets, and the evaluation of therapeutic candidates aimed at mitigating TDP-43 driven cytotoxicity or restoring normal TDP-43 localization.
The therapeutic landscape for amyotrophic lateral sclerosis (ALS) has been characterized by decades of clinical trial failures, often attributed to biological heterogeneity, end-point insensitivity, and a profound evidence gap regarding target engagement. With TAR DNA-binding protein 43 (TDP-43) aggregation emerging as a hallmark feature in the vast majority of ALS cases, new precision-medicine modalities - most notably the proteolysis-targeting chimera (PROTAC) CTx1000 - aim to address the underlying causal pathology through selective degradation of mislocalized TDP-43. This review critically evaluates the regulatory hurdles and trial design deficiencies that have historically undermined ALS clinical development, and incorporates the dual sequestration hypothesis as a framework to interpret the convergence of TDP-43 pathology across neurodegenerative diseases. It concludes that it is imperative that the field adopts more rigorous biomarker-led methodologies, and that although target-specific degraders offer a sophisticated technological leap, their success depends on addressing fundamental knowledge gaps in target engagement, age-dependent vector tropism, and trial design architecture.
Michael A. S. Guth· Drug Discovery Today· 0 citations
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive dysfunction and loss of upper and lower motor neurons. Although motor neuron degeneration ultimately drives paralysis, neuronal dysfunction may precede cell death by a prolonged interval, suggesting that vulnerable neurons engage stress-adaptive programs that permit survival despite impaired function. Cellular senescence represents one such persistent stress response and has increasingly been implicated in neurodegenerative disease, including disorders associated with TDP-43 pathology. Here, we investigated whether senescence-associated molecular states are present in vulnerable motor neurons in ALS and whether they differ according to anatomical region and phosphorylated TDP-43 (pTDP-43) pathology. Postmortem primary motor cortex, cervical spinal cord, and lumbar spinal cord were obtained from the Department of Veterans Affairs Biorepository Brain Bank from individuals with ALS classified as pTDP-43-positive or pTDP-43-negative, together with non-ALS controls. Targeted bulk transcriptomic profiling was combined with GeoMx Digital Spatial Profiling of individual motor neurons to characterize disease-, region-, and pathology-associated molecular phenotypes while preserving anatomical context. Across ALS cases, we identified alterations in pathways related to cell-cycle regulation, RNA processing, mitochondrial function, proteostasis, inflammation, and synaptic signaling. These signatures varied by anatomical region and pTDP-43 status, indicating substantial heterogeneity in the molecular response to ALS pathology. Despite these differences, both ALS groups exhibited convergent proteomic and transcriptomic features associated with cellular senescence. These findings identify senescence-associated molecular states within vulnerable neuronal populations in ALS and support a model in which persistent stress adaptation may permit neuronal survival while contributing to progressive cellular dysfunction. This spatially resolved analysis links neuronal phenotype to anatomical and pathological context and supports further evaluation of senescence-associated pathways as therapeutic vulnerabilities in ALS.
P. H. Doyle, Shiva Kazempour Dehkordi, Timothy C. Orr et al.· bioRxiv· 0 citations
TDP-43 proteinopathies, encompassing amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and limbic-predominant age-related TDP-43 encephalopathy (LATE), represent a heterogeneous spectrum of devastating neurodegenerative disorders. For decades, the diverse clinical presentations of these diseases have complicated antemortem diagnosis and hindered the development of disease-modifying therapies. However, recent breakthroughs in basic science are beginning to address these clinical barriers, although substantial hurdles to practical clinical application remain. Structural elucidation via cryo-electron microscopy (Cryo-EM) has shattered the single-protein amyloid dogma by revealing that TDP-43 can form hetero-amyloid filaments with ANXA11, thereby providing a molecular basis for pathological strain diversity. Concurrently, the pathogenic focus has shifted toward nuclear loss of function, which triggers a systemic “RNA crisis” characterized by aberrant alternative polyadenylation (APA) and cryptic exon inclusion (e.g., STMN2, UNC13A). Crucially, this metabolic collapse is profoundly exacerbated by patient-specific genetic risk factors, acting synergistically in a “two-hit” model of neurodegeneration. To translate these findings to the clinic, next-generation diagnostic tools are emerging. Integrating neuron-derived extracellular vesicle (EV) isolation with Seed Amplification Assays (SAAs) holds promise to help overcome the structural camouflage that limits current PET imaging, potentially offering ultra-sensitive, functional strain identification in biofluids. While these structural and diagnostic milestones provide a strong foundation for precision medicine, major challenges in assay standardization and clinical validation must be addressed. Advanced therapeutic strategies—namely, splice-switching antisense oligonucleotides (ASOs) that directly restore RNA metabolism, combined with the targeted suppression of neuronal hyperexcitability—are now entering clinical trials. This review synthesizes how decoding the structural and RNA-metabolic complexities of TDP-43 is paving a promising pathway from bench to bedside, while critically discussing current translational limitations.
Importance
Classifying disease based on underlying pathobiology rather than clinical phenotype has implications for the development of biomarkers and therapy development.
Observations
Transactive response DNA-binding protein 43 kDa (TDP-43) pathology is observed across a range of clinically defined neurodegenerative disorders including limbic predominant age-related encephalopathy (LATE), most cases of amyotrophic lateral sclerosis (ALS), inclusion body myositis, multisystem proteinopathy, and approximately half the cases of frontotemporal dementia (FTD). Despite this shared biology, the current nosology for these neurodegenerative disorders is based on their distinct clinical phenotypes. An alternative approach recognizes the central role of TDP-43 pathology in disease pathogenesis, reserving the use of clinical terms like ALS, FTD, or LATE to describe phenotypic manifestations of underlying pathobiology. This approach also recognizes the converging biomarker and neuropathological data indicating that pathology begins presymptomatically, before the overt clinical manifestations of disease appear.
Conclusions and Relevance
In proposing a pathobiological definition of disease, the goal is to provide a road map for developing biomarkers that accurately reflect the underlying pathobiology of disease and for advancing therapeutic candidates that effectively target fundamental disease mechanisms.
M. Benatar, SJ Barmada, Gregory A Jicha et al.· JAMA Neurology· 1 citation
TDP-43 pathology is a hallmark of Amyotrophic Lateral Sclerosis (ALS), yet no therapeutic strategy effectively targets its upstream molecular consequences. Here, we investigated whether the anti-TDP-43 intrabody scFv B1 modulates neuroinflammatory and metabolic pathways in a preclinical ALS model, and whether these effects translate into functional benefit after symptom onset. Using phage display, we previously identified single-chain variable fragments (scFvs) binding TDP-43, including the candidate therapeutic scFv B1. In NSC-34 motor neuron-like cells overexpressing human wildtype TDP-43, B1 reduced NF-κB activation, consistent with disruption of TDP-43–driven inflammatory signaling. For in vivo assessment, B1 was delivered via AAV-CAP.B10 after symptom onset in the hTDP-43(WTxA315T) transgenic mouse model, enabling neuro-specific expression. Two cohorts were analyzed - longitudinal (nine months) and terminal (six months post-treatment) - through behavioral testing, PET imaging, metabolomics, transcriptomics, and plasma biomarker analyses. B1 achieved robust CNS expression and modulated several disease-relevant molecular pathways. RNA-sequencing revealed attenuation of NF-κB–related inflammatory signatures and partial normalization of metabolic and trophic gene expression. Metabolomic profiling identified shifts toward wild-type-like levels in oxidative stress, mitochondrial, and membrane phospholipid metabolites. Despite these molecular effects, symptomatic B1 administration did not improve motor behavior or reduce plasma neurofilament light chain (NfL) concentrations. Notably, plasma TDP-43 levels were stabilized, indicating systemic target engagement. Collectively, scFv B1 modulates upstream pathogenic processes associated with TDP-43 proteinopathy but is insufficient to reverse established neurodegeneration after symptom onset, underscoring the need for earlier and likely combinatorial intervention strategies in ALS.
Y. Al Ojaimi, A. Dupuis, M. Palla et al.· Neurotherapeutics· 0 citations
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