Biology subjects

Stoehr, J.

Publications and source records attributed to Stoehr, J..

5 recordsLinked to original sources

bioRxiv2026

Pulsed priming with the FAK inhibitor narmafotinib enhances both gemcitabine/Abraxane and FOLFIRINOX chemotherapy response in pancreatic cancer

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a particularly lethal malignancy with few treatment options available. Extensive remodelling of extracellular matrix (ECM) generates a highly fibrotic tumour landscape, which impairs therapeutic response. ObjectiveWe investigated whether stromal priming via the highly specific Focal Adhesion Kinase (FAK) inhibitor narmafotinib (AMP945) in combination with the two major standard-of-care chemotherapies in PDAC, gemcitabine/Abraxane and FOLFIRINOX, reduces fibrosis and enhances treatment efficacy. Design3D organotypic matrices, intravital imaging, and in vivo subcutaneous and orthotopic PDAC models were used to provide a rationale for a first-line priming regimen of narmafotinib prior to chemotherapy. ResultsNeoadjuvant chemotherapy induces fibrosis in PDAC indicating a need for upfront first-line priming of the ECM to normalise the stroma for optimal treatment response. Narmafotinib is a new potent small molecule FAK inhibitor. Phase I safety data shows excellent safety, tolerability, and pharmacokinetics following oral administration in humans. We reveal that narmafotinib treatment during early ECM remodelling ( priming) reduces fibrosis, while limiting subsequent PDAC invasion. Moreover, intravital imaging demonstrates real-time FAK inactivation and cell cycle stalling, leading to improved chemotherapeutic efficacy upon narmafotinib priming in vivo. Long-term assessment in patient-derived models shows that narmafotinib priming prior to gemcitabine/Abraxane or FOLFIRINOX reduces PDAC progression and extends survival in both chemotherapy settings. ConclusionsOur results using these Phase II-ready drug combinations strongly support the clinical assessment of narmafotinib in PDAC. Narmafotinib is currently in Phase Ib/IIa trials, assessing a pulsed dosing regimen prior to gemcitabine/Abraxane, and warrants further clinical assessment in combination with FOLFIRINOX. SIGNIFICANCE OF THIS STUDYO_ST_ABSWhat is already known on this topicC_ST_ABSO_LIPancreatic cancer (PC) is one of the most lethal malignancies and is characterised by a dense, fibrotic stroma, which impairs chemotherapy efficacy. C_LIO_LIThe non-receptor tyrosine kinase FAK is known to promote cancer fibrosis and therefore represents a therapeutic target to normalise the PC stroma and to improve chemotherapy performance. C_LI What this study addsO_LINeoadjuvant chemotherapy induces early fibrosis indicating a need for upfront first-line priming of the ECM to blunt or normalise stromal fibrosis for optimal response to therapy. C_LIO_LIThe small molecule inhibitor narmafotinib (which is currently under Phase Ib/IIa clinical trial assessment) shows high specificity towards FAK as well as desirable pharmacokinetics and pharmacodynamics in healthy human volunteers. C_LIO_LIEarly short-term narmafotinib priming reduces fibrosis and improves the efficacy of subsequent standard-of-care gemcitabine/Abraxane chemotherapy. C_LIO_LIFOLFIRINOX (oxaliplatin, irinotecan, leucovorin and 5-fluorouracil) is a multi-agent chemotherapy preferentially used in PDAC patients with good performance status. Our results demonstrate that narmafotinib priming also improves FOLFIRINOX efficacy, leading to extended survival in patient-derived PDAC models. C_LI How this study might affect research, practice, or policyO_LIThis study supports the clinical development of narmafotinib in combination with both gemcitabine/Abraxane (ACCENT trial) and further FOLFIRINOX standard-of-care chemotherapies for PDAC patient treatment. C_LIO_LIThe first-line priming strategy and early ECM normalisation used in this study may also be applicable to other combination therapy settings and warrants further investigation in ongoing clinical studies. C_LI

cancer biology↗

bioRxiv2025

Astrocytic lysosome deficits reduce alpha-synuclein degradation and induce spread of pathology

Parkinsons Disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons in the substantia nigra due to Lewy body aggregates, primarily composed of misfolded alpha-synuclein (Syn). While PD progression is thought to be driven by a prion-like spread of Syn aggregates between neurons, the role of astrocytes remains unclear. Observations of Syn pathology in PD patient astrocytes suggest their potential involvement in processing aggregates. To investigate this, we studied astrocytes interactions with Syn pre-formed fibrils (PFFs) and their effects in astrocyte-neuron co-cultures on the spread of seed-competent Syn. Primary astrocytes quickly internalized and degraded Syn PFFs. However, degradation was significantly hindered by lysosome-compromising agents like chloroquine, Leupeptin, or CA-074. Adding astrocytes to neuron cultures reduced endogenous Syn aggregation, indicating their role in mitigating Syn pathology. When lysosome efficiency in astrocytes was compromised, their anti-seeding effect diminished. Moreover, lysosome-compromised astrocytes preloaded with Syn PFFs enhanced Syn pathology in neurons, whereas unimpaired astrocytes did not. These findings suggest astrocytes can modulate and contribute to Syn pathology spread, playing a significant role in PD pathogenesis.

neuroscience↗

bioRxiv2025

ROCK2 inhibition has a dual role in reducing ECM remodelling and cell growth, while impairing migration and invasion

The Rho-associated coiled-coil containing protein kinases 1/2 (ROCK1/2) are key signalling proteins involved in the regulation of the actin cytoskeleton and control a variety of cellular processes. This includes cell proliferation, stemness, cell migration and invasion as well as actomyosin contraction and extracellular matrix (ECM) remodelling. Due to a lack of ROCK2 specific inhibitors, previous pharmacological studies of ROCK function have relied on pan-ROCK1/2 inhibition. Here, we use the ROCK2 specific inhibitor, GV101, in the context of breast cancer (BC) models to uncouple the effects of ROCK2 pharmacological inhibition on both epithelial and stromal fibroblast cell populations. We demonstrate that ROCK2 inhibition with GV101 reduces fibroblast-mediated remodelling of pre-existing and de novo synthesised ECM resulting in a reduction in biomechanical stiffness, while also limiting epithelial cell growth in 2D and 3D settings. We also demonstrate that ROCK2 inhibition exposes epithelial cell vulnerability to fluid flow-induced shear stress. Furthermore, using 3D co-cultures we reveal that GV101 reduces single-cell migratory capacity, while the disruption of stromal ECM architecture is sufficient to impede collective cell migration and invasion. Finally, we assessed ROCK2 expression in human BC patient tumours revealing that ROCK2 expression is up-regulated during BC progression and that high ROCK2 expression correlates with poor patient outcome in the triple-negative subtype of BC. Together, these results demonstrate that ROCK2 specific inhibition disrupts key functions in both epithelial cell and stromal fibroblast compartments warranting further assessment of ROCK2 in highly proliferative, fibrotic or metastatic diseases, such as BC. HighlightsO_LIFibroblast-mediated remodelling of pre-existing and de novo synthesised extracellular matrix is reduced upon ROCK2 specific targeting. C_LIO_LIROCK2 inhibition impairs epithelial cancer cell growth and colony formation in 2D and 3D contexts, while also limiting single-cell migration and cell survival upon fluid flow-induced shear stress. C_LIO_LIROCK2 targeting during fibroblast-mediated ECM remodelling is sufficient to disrupt collective cell migration as well as 3D invasion into organotypic fibroblast-contracted collagen matrices. C_LIO_LIROCK2 expression is up-regulated during breast cancer progression and high expression correlates with poor patient outcome in triple-negative breast cancer. C_LI

cell biology↗

bioRxiv2023

An approach to characterize mechanisms of action of anti-amyloidogenic compounds in vitro and in situ

Aggregation of amyloidogenic proteins is associated with neurodegenerative disease and its modulation is a focus of drug development efforts. However, the physicochemical properties and structural heterogeneity of amyloidogenic proteins hinder the mechanistic understanding of anti- amyloidogenic compounds. Further, modes of interaction with amyloidogenic proteins are often probed in vitro using purified protein samples, even though these models may not capture in vivo protein structures and do not enable identification of off-target effects. We have developed a modular structural proteomic pipeline based on limited proteolysis coupled to mass spectrometry (LiP-MS) with improved, amino acid level-resolution, to probe the mechanism of action of anti- amyloidogenic compounds. We demonstrate our approach by analysing the interactions of six known or putative anti-amyloidogenic compounds and the amyloid binder Thioflavin T (ThT) with different structural forms of the amyloidogenic Parkinsons disease (PD) protein -Synuclein. Our approach enables determination of putative interaction sites, identification of whether interactions are covalent or non-covalent, and crucially, can probe for interactions of compounds with physiological structures of -Synuclein in complex cell and tissue extracts and identify off-targets. In vitro analyses with our pipeline showed that the green tea polyphenol EGCG induces an N- and C-terminus- dependent compaction of the unstructured -Synuclein monomer, detected preferential interactions of ThT with the N-terminus of -Synuclein fibrils compared to the amyloid core, and showed that the most potent inhibitors of aggregation in our study (EGCG, baicalein and AC Immune compound #2) induced similar non-fibrillar end structures despite different interactions with -Synuclein monomers. Importantly, in mammalian cell lysates, -Synuclein was either a low-affinity target (for EGCG and Baicalein) or did not show evidence of compound interaction (for ThT and doxycycline) in our experimental conditions, despite both monomeric and fibrillar forms interacting with these compounds in vitro. For EGCG, we validated this result in postmortem brain homogenates from PD patients. These in situ analyses identified many additional putative cellular targets of Doxycycline, EGCG, Baicalein and ThT, suggesting that their effects in cellular or animal models of neurodegeneration are likely due to interactions with proteins other than -Synuclein and showing that anti-amyloidogenic compounds should be analyzed in situ as well as in vitro. Our modular pipeline will enable in situ screening of drugs and PET tracers for amyloid aggregates of interest as well as detailed mechanistic studies of compound action in vitro.

systems biology↗

bioRxiv2023

Pharmacological PINK1 activation ameliorates Pathology in Parkinson's Disease models

PINK1 loss-of-function mutations and exposure to mitochondrial toxins are causative for Parkinsons disease (PD) and Parkinsonism, respectively. We demonstrate that pathological -synuclein deposition, the hallmark pathology of idiopathic PD, induces mitochondrial dysfunction and impairs mitophagy, driving accumulation of the PINK1 substrate pS65-Ubiquitin (pUb) in primary neurons and in vivo. We synthesized MTK458, a brain penetrant small molecule that binds to PINK1 and stabilizes an active heterocomplex, thereby increasing mitophagy. MTK458 mediates clearance of -synuclein pathology in PFF seeding models in vitro and in vivo and reduces pUb. We developed an ultrasensitive assay to quantify pUb levels in plasma and observed an increase in pUb in PD subjects that correlates with disease progression, paralleling our observations in PD models. Our combined findings from preclinical PD models and patient biofluids suggest that pharmacological activation of PINK1 is worthy of further study as a therapeutic strategy for disease modification in PD. HighlightsO_LIDiscovery of a plasma Parkinsons Disease biomarker candidate, pS65-Ubiquitin (pUb) C_LIO_LIPlasma pUb levels correlate with disease status and progression in PD patients. C_LIO_LIIdentification of a potent, brain penetrant PINK1 activator, MTK458 C_LIO_LIMTK458 selectively activates PINK1 by stimulating dimerization and stabilization of the PINK1/TOM complex C_LIO_LIMTK458 drives clearance of -synuclein pathology and normalizes pUb in in vivo Parkinsons models C_LI

neuroscience↗