Jul 2026· Journal of Medicinal Chemistry· Vol 69, pp. 19451 - 19481· 0 citations· 61 references
Medicine
TL;DR
It is found that these inhibitors reduce TDP-43 phosphorylation levels in neuroblastoma cells and FTD patient-derived models, and restores cognitive deficits, conferred neuroprotection in the frontal cortex, and reduced microglial activation in an FTD-TDP mouse model, supporting its therapeutic potential.
Abstract
Transactive response DNA-binding protein of 43 kDa (TDP-43) is a pathological hallmark of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Modulation of TDP-43 pathology represents a promising disease-modifying strategy. Tau tubulin kinase 1 (TTBK1) has emerged as a relevant therapeutic target; however, selectivity over the TTBK2 isoform is required to avoid ciliogenesis-related liabilities. Here, we report the discovery of selective, brain-penetrant TTBK1 inhibitors through a structure-guided medicinal chemistry program. Lead compounds exhibit potent and selective TTBK1 inhibition, no impact on ciliogenesis, and central nervous system exposure. We found that these inhibitors reduce TDP-43 phosphorylation levels in neuroblastoma cells and FTD patient-derived models. The optimized lead compound demonstrated a brain-to-plasma ratio of 3:1, a maximum tolerated dose, and a wide therapeutic window. In vivo, administration restored cognitive deficits, conferred neuroprotection in the frontal cortex, and reduced microglial activation in an FTD-TDP mouse model, supporting its therapeutic potential.
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.
Abstract Neurodegenerative disorders are increasing in prevalence, yet disease-modifying therapies remain limited. Dual-specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A) phosphorylates tau and regulates inflammatory signaling, making it a potential therapeutic target for neurodegenerative diseases. To investigate the relevance of DYRK1A to primary tauopathies, we first evaluated DYRK1A protein levels in the superior frontal gyrus of individuals with Pick’s disease, corticobasal degeneration, and progressive supranuclear palsy. DYRK1A protein expression was significantly elevated in individuals with primary tauopathies compared with healthy controls and positively correlated with Braak stage. Conversely, DYRK1A levels inversely correlated with last Mini-Mental State Examination (MMSE) scores and brain weight, linking elevated DYRK1A expression to disease severity. We next developed DYR533, a selective, orally bioavailable, brain-penetrant small-molecule DYRK1A inhibitor with an S(35) score of 1.4 nM based on a 403-target KINOMEscan assay. Mechanistically, DYR533 prevented the autophosphorylation of newly translated DYRK1A, rendering the kinase inactive and thereby inhibiting phosphorylation of downstream substrates. We next evaluated the therapeutic efficacy of DYR533 in the PS19 mouse model of primary tauopathy, assessing tau hyperphosphorylation, neuroinflammation, motor function, and spatial cognition. DYR533 reduced tau hyperphosphorylation at threonine 217, threonine 181, and serine 396, and attenuated the expression of neuroinflammatory cytokines and chemokines implicated in disease progression. In PS19 mice, DYR533 treatment produced modest improvements on behavior. Together, these findings establish an association between elevated DYRK1A and disease severity in human primary tauopathies and demonstrate that pharmacological inhibition of DYRK1A with DYR533 reduces pathological tau phosphorylation and neuroinflammatory signaling in vivo.
Ramon Velazquez, Samantha Bartholomew, Wendy Winslow et al.· Research Square· 0 citations
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
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
This study evaluates the therapeutic potential of the lipid-conjugated antimiR-23b, X82108, designed to promote MBNL1/2 upregulation through inhibition of miR-23b, and highlights X82108 as a promising systemic therapy for DM1.
D. Piqueras-Losilla, Andrea García-Rey, Aline Huguet-Lachon et al.· Cell Reports Medicine· 0 citations
Key biological mechanisms underlying TDP-43 pathology, emerging therapeutic strategies, and evolving approaches to clinical trial design and biomarker development are examined.
C. Estévez-Fraga, R. Álvarez-Velasco, Tariq Afroz et al.· Journal of Neurology· 1 citation
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